ASAP (As Soon As Publishable)

C–C bond activation can provide a direct reconstruction strategy of carbon skeletons to furnish a number of structurally diverse molecules. In general, regioselectivity represents the state-of-the-art owing to the existence of several different carbon–carbon bonds, having a high BDE, ∼90 kcal/mol. Here, we report a directed strategy for amides for the concise synthesis of a range of urea derivatives and carbamates via regioselective C–C bond activation enabled by the heterogeneous single-atom copper catalyst (Cu-SAC), with a turnover frequency of 249 h^–1, which is 19 times higher than that of the analogous homogeneous copper catalyst. Multitechnique characterization data show that single-atom Cu species are associated with an unsaturated coordination structure and plentiful oxygen vacancies on γ-Al₂O₃ that facilitate the adsorption of multiple coordinated amides and dioxygen, leading to high catalytic activity and selectivity. It would offer opportunities to speed up the heterogenized process of homogeneous catalysts in regioselective inert-bond activation reactions.

A Ru(II)-catalyzed straightforward and efficient strategy has been developed to construct O-alkylated arylnaphthyl thioether derivatives using arylthioacetates/arylalkylthioethers with diazonaphthoquinone via a [1,4]-oxa sigmatropic rearrangement. In a complementary method, heteroaryl thioacetate/heteroaryl alkylthioethers offer O-heteroaryl alkylnaphthyl thioether derivatives via an interesting concerted intramolecular S_NAr-type reaction. Both of these methods proceed through the formation of Ru-based quinoid carbene and sulfur ylide, respectively. A detailed mechanistic study and DFT calculations reveal that the reaction is going via a concerted manner. Postsynthetic modifications of the synthesized compounds led to sulfur-containing polyaromatic heterocycles.

To develop an environmentally benign and efficient route for converting CO₂ into value-added chemicals is of great importance. Here, we demonstrate the photocatalytic carboxylation of terminal alkynes with CO₂ at room temperature and atmospheric pressure, by copper-based porphyrinic framework photocatalysts Cu₂TCPP(M) (TCPP = 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin; M = Fe, Co, Ni, Cu). The Cu₂TCPP(Cu) nanosheets (with a small thickness of ∼5.1 nm) exhibit an extremely high performance for the reaction of 1-ethynylbenzene with CO₂ to produce 3-phenylpropiolic acid. The turnover frequency is up to 3.33 mmol g^–1 h^–1 at 10 h, which is much higher than those of the photothermally and thermally driven routes that are usually adopted for the carboxylation reactions catalyzed by metal–organic frameworks. The mechanism for the superior activity of Cu₂TCPP(Cu) nanosheets was investigated by a series of experiments and theoretical calculations. It is revealed that the Cu₂TCPP(Cu) nanosheets not only possess good photoelectronic properties but have desired molecular structure for boosting CO₂ activation, alkyne activation, and carboxylation reactions.

Disrupting the spin degeneracy of the electrocatalyst and further manipulating the related orbital electron arrangement are highly desirable for activating acetylene molecules. Herein, a squarate cobalt-based metal–organic framework (Co-MOF) ([Co₃(C₄O₄)₂(OH)₂]·3H₂O) is post-treated to accelerate the evolution from CoO₆ octahedron to CoO₅ pentahedron and further utilized for the electrochemical acetylene semihydrogenation reaction. Comprehensive analyses corroborate that the disrupted spin degeneracy of active sites originated from the breakage of the Co–O bond, which promotes the cleavage of the orbital energy level and the rearrangement of the d-orbital electron. The newly emerged half-occupied d_x²_–y² orbitals and empty d_z² orbitals in CoO₅ pentahedron concerted interplay with the bonding and antibonding orbitals of acetylene, which reduces the adsorption energy of acetylene and facilitates the activation of the inert C≡C triple bond. Thus, the defective Co-MOF exhibits the superior ethylene Faradaic efficiency of 96% and partial current density of 128 mA cm^–2 at −1.0 V vs RHE compared to that of pristine Co-MOF (FE_C2H4: 60%; J_C2H4: 66 mA cm^–2). This work delivers inspiration for spin-state regulation of active sites and sparks renewed interest in designing highly efficient electrocatalysts.

Ti precatalysts containing the titanocene moiety (Cp₂Ti–, Cp = cyclopentadienyl) can, under certain conditions, selectively produce cubic Al nanocrystals through the dehydrocoupling of alane amine adducts such as AlH₃·NMe₂Et. A systematic study of reaction conditions reveals that cubic Al nanoparticle formation occurs at a higher temperature (e.g., 65 °C) and/or higher catalyst-concentration conditions (e.g., 0.5 mol % [Ti]). Kinetic studies reveal that under these conditions nanoparticle formation and alane consumption are much faster, and cubic nanoparticle formation takes place under kinetically controlled conditions. On the other hand, employing a wide suite of TiX₄ (X = anionic ligand)-type precatalysts yielded only octahedral-shaped aluminum nanoparticles regardless of conditions. Finally, we report the synthesis of a hydride-bridged Ti–Al heterobimetallic compound from the reaction of Cp₂TiCl₂ with AlH₃·NMe₂Et and characterized it to show that it is a reaction intermediate in the Ti-catalyzed aluminum nanoparticle synthesis.

The catalytic asymmetric transformation of nitrogen atoms to prepare heterocyclic molecules is of significant value in organic synthesis and biological applications. Here, we disclose the activation of the nitrogen atom in hydrazine-derived hydrazone via an N-heterocyclic carbene (NHC) organic catalyst for highly enantioselective formal cycloaddition reactions. The range of NHC catalysis extends across several (carbon and hetero) atoms and diverse chemical bonds (C═N and N–N bonds) to activate nitrogen atoms at remote sites with excellent reactivity and (stereo)selectivity control. Our strategy for nitrogen atom activation, along with the NHC-bound diaza-diene intermediate generated during the catalytic process, offers alternative solutions for organic synthesis.

Tumor-associated MUC1 is coated with a high density of O-GalNAc glycans, which are initiated by a family of polypeptide N-acetyl-α-galactosaminyltransferases (GalNAc-Ts). However, the O-glycosylation process of MUC1 by each GalNAc-T isoform remains unclear. Here, we successfully obtained 14 human GalNAc-Ts with high catalytic activity based on a bacterial expression system. Employing MUC1-derived peptides as substrates, we systematically investigated the catalytic properties and site specificity of these GalNAc-Ts by chromatography and mass spectrometry, and found that they could be classified into two clusters. These two GalNAc-T clusters initially catalyze the threonine residue within GSTA or GVTS motifs, respectively, resulting in high O-glycosylation occupancy of both motifs. Moreover, molecular dynamics simulations and site-directed mutagenesis confirmed that the initial O-glycosite preference of GalNAc-Ts on MUC1 is controlled by two critical residues within the peptide-binding pocket. Swapping of the corresponding residues between two GalNAc-T clusters could exchange their initial O-glycosite preference. Quantum mechanics calculations further revealed the detailed catalytic mechanisms of GalNAc-Ts. Our work contributes to understanding the catalytic synthesis of multisite O-glycosylation of MUC1 by GalNAc-Ts, facilitating the development of O-glycosite-specific MUC1 vaccines.

Fischer–Tropsch synthesis (FTS) has attracted intensive attention as a nonpetroleum route for producing bulk chemicals and fuels. The controllable synthesis of high-performance Fe-based catalysts is of significance in industry. It is challenging to achieve higher activity and great stability at the same time due to the complex transformation of iron phases and numerous side reactions. Herein, two carbon species, surface carbon and penetrating carbon, were tuned by adjusting the carburization conditions (CO/H₂ ratio and temperature), aiming to control the structure of active phases. The content of penetrating carbon determines the type of iron carbides (Fe₂C and/or Fe₅C₂), among which Fe₂C exhibits higher initial activity but poor stability because of severe carbon deposits on the surface. In contrast, Fe₅C₂, with lower activity, is more stable during the reaction. Moreover, excess surface carbon covering active sites is undesired, whereas moderate preformed surface carbon (especially sp²-type carbon) plays an important role in hindering carbon further diffusion into the bulk phase and enhancing the stability of Fe₅C₂ to some extent. The combined action of these two carbon species acts as a regulator of the Fe₂C–Fe₅C₂ mixture, balancing activity and stability. This work underlines the two sides of penetrating carbon and surface carbon, emphasizing the importance of carburization manipulation. This inspires optimization of the pretreatment and reaction processes of industrial FTS catalysts.

Biomass is a renewable carbon source that comes from plants, containing chemical energy from the sun. Nitrate, which is a N-containing feedstock with a lower dissociation energy, has a rich distribution in wastewater. Renewable biomass and nitrate waste can be converted into valuable C–N products through photocatalytic processes, which is becoming promising but challenging in the production of different kinds of chemicals and fuels. Herein, we report the photoconversion of biomass and nitrate into glycine with a 765 μmol g_cat^–1 h^–1 production rate and 15.3% yield over a Ba²⁺-modified TiO₂ catalyst. The process cascades multiple reactions containing the photoreforming of biomass to glycol, nitrate reduction to NH₃, and finally, C–N coupling to glycine, among which nitrate ions play a dominant role in the selective cleavage and oxidation of biomass. Surprisingly, after hydrolysis pretreatment, biopolyols or sugars and even raw wood sawdust could react with nitrate to generate glycine. This study provides an effective catalytic system to produce glycine from renewable biomass and nitrate waste under mild conditions.

The 3-chymotrypsin-like protease (3CL-PR; also known as Main protease) of SARS-CoV-2 is a cysteine protease that is the target of the COVID-19 drug, Paxlovid. Here, we report for 3CL-PR, the pH-rate profiles of a substrate, an inhibitor, affinity agents, and solvent kinetic isotope effects (sKIEs) obtained under both steady-state and pre-steady-state conditions. “Bell-shaped” plots of log(k_cat/K_a) vs pH for the substrate (Abz)SAVLQ*SGFRK(Dnp)-NH₂ and pK_i vs pH for a peptide aldehyde inhibitor demonstrated that essential acidic and basic groups of pK₂ = 8.2 ± 0.4 and pK₁ = 6.2 ± 0.3, respectively, are required for catalysis, and the pH-dependence of inactivation of 3CL-PR by iodoacetamide and diethylpyrocarbonate identified enzymatic groups of pK₂ = 7.8 ± 0.1 and pK₁ = 6.05 ± 0.07, which must be unprotonated for maximal inactivation. These data are most consistent with the presence of a neutral catalytic dyad (Cys-SH-His) in the 3CL-PR free enzyme, with respective pK values for the cysteine and histidine groups of pK₂ = 8.0 and pK₁ = 6.5. The steady-state sKIEs were ^D₂O(k_cat/K_a) = 0.56 ± 0.05 and ^D₂Ok_cat = 1.0 ± 0.1, and sKIEs indicated that the Cys-S^–-HisH⁺ tautomer was enriched in D₂O. Presteady-state kinetic analysis of (Abz)SAVLQ*SGFRK(Dnp)-NH₂ exhibited transient lags preceding steady-state rates, which were considerably faster in D₂O than in H₂O. The transient rates encompass steps that include substrate binding and acylation, and are faster in D₂O wherein the more active Cys-S^–-HisH⁺ tautomer predominates. A full catalytic mechanism for 3CL-PR is proposed.

Limited by the violent oxidation and corrosion environment of the oxygen evolution reaction (OER) in seawater electrolysis, the design of catalysts with high activity and stability is crucial for improving the hydrogen production performance of the electrolysis cell. Herein, we report taking advantage of corrosive Cl^– in seawater to achieve rapid surface reconstruction of amorphous NiFeCoP for stable seawater splitting. The successful introduction of pulse current and P constructs Cl^– adsorption active sites to optimize the d-band center and induce the formation of NiFeCo(OH). Density functional theory calculations also verified that NiFeCo(OH) has satisfactory OER activity and chlorine exclusion properties. Benefiting from the electronic structure and reaction intermediate adsorption, NiFeCo(OH) only requires 255.3 mV overpotential to reach a current density of 100 mA cm^–2. Meanwhile, the assigned alkaline water electrolysis cell (NFCP || Pt/C) stably operates for 320 h in natural seawater at an industrial current density of 500 mA·cm^–2 with a low voltage of 1.806 V. The seawater AEM electrolyzer (NFCP || Pt/C) achieves an improved performance of high activity (2.095 V@500 mA·cm^–2) and stable operation (100 h@500 mA·cm^–2) to achieve economic seawater splitting. In summary, this work proposes a fast self-reconstruction of a high-performance seawater electrocatalyst for marine hydrogen energy.

Challenges in directly regulating the reaction pathways in the electrooxidation of formic acid have hindered widespread applications in direct formic acid fuel cells (DFAFCs). Hence, we report directly tuning the reaction pathway of formic acid oxidation (FAO) to avoid CO poisoning over the bimetallic PtCo alloys. The PtCo alloys are fabricated by using a facile one-step microwave method, avoiding the use of organic solvents and minimizing environmental pollution. The Pt₁Co₁ alloy displays a specific surface area of 17.58 m² g^–1 and exhibits a 121-fold increase in mass activity (1.18 A mg_Pt^–1) compared to its counterpart Pt (<0.01 A mg_Pt^–1). It also far outperforms Pt₃Co₁ (0.09 A mg_Pt^–1) and Pt₁Co₃ (0.95 A mg_Pt^–1) alloys. In situ attenuated total reflection infrared spectra further confirm that the bimetallic PtCo alloys catalyzed FAO through the direct pathway to CO₂ formation, suggesting that adding Co plays a crucial role in enhancing Pt’s resistance to CO poisoning. Density functional theory calculations further indicate that the incorporation of Co into the Pt coordination environment is crucial for altering the formation of transition intermediates, which can form a more stable bond with the HCOO intermediate, which is formed by breaking the O–H bond. Specifically, on the Pt₁Co₁ alloy with 50% Co incorporation, the free energy for HCOO* formation is significantly lower (−0.296 eV) compared to that of COOH* (0.028 eV). This trend is reversed when compared with pure Pt (0.196 eV for HCOO* and −0.190 eV for COOH*), thereby promoting FAO via a direct pathway. This work provides a reference for the rational development of high-efficiency Pt-based alloy electrocatalysts.

Lanthipeptides are ribosomally synthesized and post-translationally modified peptides (RiPPs) characterized by the presence of thioether cross-links called lanthionine and methyllanthionine, formed by dehydration of Ser/Thr residues and Michael-type addition of Cys side chains onto the resulting dehydroamino acids. Class II lanthipeptide synthetases are bifunctional enzymes responsible for both steps, thus generating macrocyclic natural products. ProcM is part of a group of class II lanthipeptide synthetases that are known for their remarkable substrate tolerance, having large numbers of natural substrates with highly diverse peptide sequences. They install multiple (methyl)lanthionine rings with high accuracy, attributes that have been used to make large libraries of polycyclic peptides. Previous studies suggested that the final ring pattern of the lanthipeptide product may be determined by the substrate sequence rather than by ProcM. The current investigation on the ProcM-catalyzed modification of one of its 30 natural substrates (ProcA3.3) and its sequence variants utilizes kinetic assays to understand the factors that determine the ring pattern. The data show that changes in the substrate sequence result in changes to the reaction rates of ring formation that in some cases lead to a change in the order of the modifications and thereby bring about different ring patterns. These observations provide further support that the substrate sequence determines to a large degree the final ring pattern. The data also show that similar to a previous study on another substrate (ProcA2.8), the reaction rates of successive reactions slow down as the peptide is matured; rate constants observed for the reactions of these two substrates are similar, suggesting that they reflect the intrinsic activity of the enzyme with its 30 natural substrates. We also investigated whether rates of formation of single isolated rings can predict the final ring pattern of polycyclic products, an important question for the products of genome mining exercises, as well as library generation. Collectively, the findings in this study indicate that the rates of isolated modifications can be used for predicting the final ProcM-produced ring pattern, but they also revealed limitations. One unexpected observation was that even changing Ser to Thr and vice versa, a common means to convert lanthionine to methyllanthionine and vice versa, can result in a change in the ring pattern.

Synthesis of robust and hydrothermally stable PGM/ceria materials for NO, CO, and hydrocarbon abatement remains a formidable challenge, as ceria and PGMs are known to sinter severely >800 °C under hydrothermal conditions, leading to irreversible activity loss. Herein, we tackle this challenge by synthesizing well-defined catalysts with atomically dispersed rhodium supported on ceria with varying abundance of (100), (101), and (111) facets. Evaluation of these catalysts for NO reduction by CO as well as CO and propylene oxidation under model and industrially relevant conditions reveals pronounced reactivity and stability differences. Different modes of interaction of Rh ions with the ceria facets and their facile reducibility were shown to be the crucial parameters controlling reactivity, resulting in pronounced activity and stability variations. Facet-dependent poisoning of surfaces by nitrites was identified as the main reason for deactivation of the catalysts at low temperature, which is mitigated for (111) ceria facets. (111)-enriched ceria nanoparticles survive very harsh hydrothermal aging at 950 °C by maintaining and preserving (111) facets, unlike other ceria nanoparticles which sinter into poorly defined shapes. Thus, putting atomically dispersed PGM sites on (111) ceria facets lead to the catalytic material with the highest activity and stability for all studied reactions, providing the pathway to catalysts that can endure extremely harsh hydrothermal aging conditions.

Due to the unique properties of rare-earth (RE) metals, RE catalysts demonstrate distinctive catalytic performance in hydrogenation and related transformations. In typical RE catalytic systems, the roles and function modes have been studied and are relevant to ligands. In recent years, heterobimetallic catalytic systems have emerged for efficient hydrogenation and related transformations. Among these systems, heterobimetallic catalysts with transition metal (TM)-RE combinations integrate the characteristics of TM catalysis and RE catalysis, exhibiting a TM-RE bifunctional effect with remarkable activity and selectivity. However, the roles of RE metals in TM-RE bifunctional catalysis remain ambiguous. This theoretical study takes the Ni–Y system as a study case, aiming to elucidate the significant roles of the RE center in the TM-RE bifunctional effect on catalytic alkyne semihydrogenation. The results suggest that dynamic coordination can occur at the Y center due to its large size and coordination ability, which accepts the binding of phosphine groups of the ligand. The dynamic coordination of phosphine groups to the large-size RE center assists the Ni center in releasing vacant sites for substrate in-cage binding and reduces the steric effect on the Ni center. Meanwhile, the Lewis acidic RE center can stabilize the bridging hydride, which is crucial for H₂ activation and hydrogenation. The TM-RE bifunctional effect promotes the reaction. During the H₂ activation stage, due to the stabilization of nickel hydrides by yttrium, the fac-pathway is more favored. The Ni–H–Y bridging structure is maintained during the initial hydride insertion in the semihydrogenation stage, which is crucial for the reaction. Additionally, the use of the more active terminal hydride makes the terminal hydride pathway a more plausible mechanism. Benefiting from the capability of yttrium to accept the dynamic coordination of phosphine groups, thereby releasing steric hindrance and stabilizing the bridging hydride concurrently, (Z)/(E)-isomerization can proceed to achieve (E)-selectivity through the H₂-assisted Ni–Y bifunctional pathway with a relatively low energy barrier. Owing to the RE-bridging hydride stabilization effect, the thermodynamic properties of intermediates are closely related to the size of the RE metal center, thereby influencing the activity and the (Z)/(E)-selectivity. These results underscore the important roles of the RE center in TM-RE bifunctional catalysis, offering valuable insights into the future design of effective bifunctional TM-RE catalysts.

5-Amino-1-pentanol (APO) is an important nitrogen-containing chemical with versatile applications. However, its synthesis is still not efficient. Here, we report the synthesis of APO from biomass-derived furfurylamine (FAM) via the direct cleavage of its α–C–O bond neighboring the −CH₂NH₂ group at ambient temperature. Pt/TiO₂ catalysts exhibited high efficiency and stability in the FAM hydrogenolysis to APO, affording a high yield of 85.4% at 30 °C and 2.0 MPa of H₂ in water. The high efficiency of Pt/TiO₂ was found to be related to its superior activity for the cleavage of the α–C–O bond in FAM, relative to the hydrogenation of the furan ring on the corner and edge sites of the Pt surfaces. This work provides a viable approach for the precise cleavage of the α–C–O bond neighboring the −CH₂NH₂ group in the furan ring under mild conditions toward the efficient production of APO and its derivatives.

Electrochemical nitrate reduction reaction (NO₃^–RR) to ammonia offers a promising solution to environmental and energy challenges, converting a ubiquitous pollutant in aquatic environments into a carbon-free energy carrier and essential chemical feedstock. While considerable research has focused on electrocatalyst development, relatively less attention has been given to device engineering and electroanalytical techniques that play crucial roles in enhancing the performance of the electrocatalytic NO₃^–RR, especially at such low concentrations. Here, Cu_xRu_y alloy catalysts were synthesized, and their electrocatalytic performance was investigated by using various electroanalytical techniques in H-type and membrane-electrode-assembly (MEA) configurations. The results revealed the poor performance of the electrocatalytic NO₃^–RR at low NO₃^– concentrations (0.01 M) in H cells due to the mass transfer loss, promoting the competing hydrogen evolution reaction. Pulsed electrolysis was leveraged as an effective strategy to enhance ammonia yield rate (3-fold) and Faradaic efficiency (FE) (2-fold) compared to the potentiostatic (i.e., constant voltage) condition at low nitrate concentrations, primarily by impacting the local microenvironment. Additionally, an MEA cell was constructed with anionic and bipolar membranes, and a comparative study was conducted by examining cell voltage, selectivity, and energy efficiency. The findings exhibited that membrane type significantly influences cell voltage and system efficiency. Notably, the CuRu alloy catalyst in an MEA system with an anion exchange membrane achieved a FE exceeding 90% at 200 mA cm^–2 with the highest NH₃ yield rate of 5.74 ± 0.27 mmol h^–1 cm^–2 and stability over 100 h assessed at 600 mA cm^–2. The insights gained from this work could inform the rational design of the electrochemical NO₃^–RR to ammonia with enhanced catalytic performance at low nitrate concentrations.

The catalytic hydrogen transfer (CHT) cascade reaction coupling alcohols with nitro compounds to synthesize imines is highly significant due to its remarkable efficiency and atom economy. However, the complicated multistep reaction process makes single-site catalysts exhibit unsatisfactory catalytic performance for the CHT cascade reaction. Herein, inspired by the findings of DFT calculations that Co nanocluster (Co_NC) and Co single atom (Co_SA) can act as the optimal active sites for alcohol oxidation and nitro reduction, respectively, one dual-active site catalyst (Co_SA-Co_NC/CN), containing Co_SA and Co_NC sites, was synthesized by a two-step vacuum pyrolysis strategy. Benefiting from the relay-like tandem catalysis of Co_NC and Co_SA, Co_SA-Co_NC/CN achieved an impressive 93% nitrobenzene conversion and 99% imine selectivity at 160 °C in 4 h, with a record turnover frequency of 20.9 h^–1. This work provides insights into the functions of single-atom and nanocluster active sites in the CHT cascade reaction and sheds light on the rational preparation of tandem catalysts.

Photoredox catalysis is an appealing strategy for the C–S bond formation. Herein, we disclose the photocatalytic reductive hydrodisulfuration of electron-deficient alkenes for the synthesis of unsymmetrical disulfides. Mechanistic studies indicate that while the radical initiation occurs in this reaction, the perthiolate anion generated from the reduction of tetrasulfides via single-electron transfer is the key electron donor for the conjugate addition. This methodology exhibits broad functional group tolerance and allows the late-stage installation of disulfide motifs into marketed drugs and the preparation of peptides containing the disulfide bond under cysteine-free conditions. Moreover, the mechanism of ionic addition is further explained by control experiments and computations.

While alkenylborons have emerged as powerful precursors for the stereospecific construction of substituted alkenes, efficient synthetic methods toward stereodefined trisubstituted alkenylborons remain limited. Herein, we report a modular and practical approach for the stereoselective synthesis of E-trisubstituted alkenylborons through the nickel-catalyzed three-component reductive coupling of two readily available carbon electrophiles with an ethynyl-Bdan reagent. The protocol exhibits a broad substrate scope and good functional group tolerance, providing expedient access to a variety of trisubstituted alkenylborons with exclusive E-selectivity. The work demonstrates the possibility of applying ethynyl-Bdan as a type of boron reagent in organic synthesis.

A catalytic protocol has been developed to access Fischer carbene nickel complexes using acylsilanes as stable and readily available precursors. The as-generated Fischer carbene complexes exhibit versatile reactivity, including cyclopropanation with alkenes, α-C–H insertion reactions, and two-component C–H addition to norbornene, which demonstrates the broad utility of the nickel(0)/acylsilane system for the catalytic applications of Fischer carbene complexes.

Halloysite clay nanotubes (HNTs) are emerging nanomaterials for numerous environmental applications, including catalysis and biomass valorization. The efficacy of halloysite as a nanoplatform for the catalytic conversion of biomass can be accurately evaluated by combined approaches based on experimental investigations and computational modeling. Recently, many efforts have been made to properly describe the most peculiar features of halloysite by focusing on its structural and interfacial features through computational studies, which are challenging for natural clay nanoparticles yet crucial for the design of novel catalysts to be exploited in biomass conversion. Within this framework, this review critically and extensively discusses recent advancements related to the use of halloysite in different catalytic processes, such as enzymatic reactions, precious- and nonprecious-metal- and alloy-catalyzed reactions, and acid-activated mechanisms. The research gap on the computational modeling of biomass chemical conversion occurring on halloysite surfaces is highlighted throughout this review, together with the latest experimental achievements. To optimize the catalytic efficiency of halloysite-based materials for biomass valorization, future efforts should focus on the implementation of experimental data with calculations provided by proper models in a synergistic approach.

The reverse water–gas shift (RWGS) reaction is a promising pathway for CO₂ utilization, while discovering optimal active species remains a significant challenge. Here we fabricated an ultrasmall Ru-Ru₂P heterostructure, in which the Ru nanoparticle is in close contact with the Ru₂P nanoparticle and modified by Ru₂P species. Through exploring the catalytic performance of ruthenium phosphides, we found that the product selectivity for CO₂ hydrogenation can be completely tuned from CH₄ to CO through phosphidation of a SiO₂-supported Ru catalyst because the distinctive surface structure of ruthenium phosphides interdicts the deep hydrogenation of the strongly bonded CO intermediate to CH₄. Enhanced catalytic activity is achieved on the Ru-Ru₂P heterostructure compared to pure Ru₂P and RuP owing to its stronger capability to adsorb and activate CO₂ and H₂. Following a 100 h high-temperature reaction, the Ru-Ru₂P heterostructure remained stable with a nearly constant CO production rate and 100% CO selectivity. Furthermore, an in situ diffuse reflectance infrared Fourier transform spectroscopy study unveils that the RWGS reaction on the ruthenium phosphides proceeds through the redox mechanism. Our work demonstrates that the Ru-Ru₂P heterostructure acts as the optimized active species with high activity and CO selectivity and highlights that the inert catalytic activity for CO intermediate hydrogenation plays a more crucial role in determining CO selectivity in catalytic CO₂ hydrogenation than the generally considered weak CO adsorption.

The effects of the electrical double layer (EDL), which pertain to the compositions and interactions among electrolyte species, significantly impact the catalytic process. There is a pressing need to investigate the role of electrolyte components and to deepen our understanding of EDL effects. In this study, we tune the water activity within a range of anionic surfactants featuring different functional groups to adjust H₂ evolution activity and CO₂ reduction selectivity. We demonstrate that these anionic surfactants are active in the local reaction environment under a cathodic potential. The enhanced selectivity of CO₂ to CO can be attributed to the robust interfacial hydrogen-bonding network reformed by the anionic surfactants. This network diminishes the water dissociation activity and promotes the hydrogenation step in CO₂ reduction. Notably, the electrolyte incorporating anionic surfactants improves the CO₂ reduction performance, registering CO Faradaic efficiencies of 89.7% (RSO₃^–, SDS), 97.5% (RSO₄^–, SLS), 98.4% (RPO₄^2–, SMP), and 98.9% (RCOO^–, SL) at −1.2 V versus RHE, thereby outperforming the blank KHCO₃ electrolyte (53.1%). This research underscores the crucial influence of anionic additives in the CO₂RR.

The utilization of zeolites in the catalytic cracking of plastics has garnered attention as a promising recycling method. Zeolitic micropores are uniform and exhibit shape selectivity, but their sizes are very small compared to those of polymer molecules. Consequently, the reactions occurring on the external surfaces and near the pore mouths of zeolites are crucial for polymer cracking. However, the role of zeolitic surfaces in polymer cracking has not been clarified. In this study, we controlled the external surfaces of zeolites (particle size, external surface areas, and location of the surface acid sites). These catalysts were employed in the cracking of low-density polyethylene (LDPE), and the effects of their surface properties on the reactions were investigated. The external surface areas of ZSM-5 zeolites were controlled by changing their particle sizes and desilication conditions. Although the LDPE cracking temperatures strongly depended on the zeolitic surface area, the temperature was plateaued when the external surface area exceeded approximately 90 m²/g. To investigate the role of surface acidity further, we prepared core–shell-type ZSM-5/silicalite-1 zeolites with various shell thicknesses. The silicalite-1 coating significantly reduced the LDPE cracking activity of ZSM-5 zeolites, and the cracking temperature increased with the increase in silicalite-1 shell thickness. However, the gaseous product distributions were shifted toward lower hydrocarbons by the increase in inert shell thickness, indicating that the initial cracking and excessive reactions on the external acid sites led to the production of large C5 and C6+ products. This study revealed that the initial cracking reactions occur at the inner acid sites near the pore mouth as well as the external surface and that the smaller reactants diffuse into deep active sites. These findings are anticipated to offer valuable insights into the development of zeolite catalysts suitable for the catalytic cracking of polymers.

Selective direct alkylation of indenes is important for the synthesis and decoration of indene derivatives. In contrast to traditional alkylation methods, using unactivated alcohol as alkylation reagents via borrowing hydrogen or hydrogen autotransfer is highly attractive. However, the nature of the high-lying lowest unoccupied molecular orbital of the condensation intermediate raises a big challenge for the development of the BH system for the alkylation of indenes using alcohols. Through tuning the stability and the reactivity of the metal-hydride species by theoretical prediction, herein, we succeeded in developing a non-noble Mn-catalyzed selective direct monoalkylation or dialkylation of indenes under mild conditions, producing the corresponding versatile alkylated indenes in satisfactory yields. A broad scope of substrates including primary benzylic, aliphatic, amino, hydroxyl, and second alcohols as well as various indenes are tolerated in the system. Additionally, this method could be used for the synthesis of potential precatalyst complexes and bioactive molecules. Mechanistic studies including control experiments, kinetic investigations, kinetic isotope effect, deuterium labeling experiments, and density functional theory calculations, reveal the proper metal-hydride for a successful BH process.

Developing a coelectrolysis system of the nitrate reduction reaction (NO₃RR) and polyethylene terephthalate-derived ethylene glycol oxidation reaction (EGOR) is of great significance for the electrocatalytic-paired upcycling of waste plastics and nitrate wastewater. However, a huge challenge remains in the exploitation of highly active catalytic electrodes. Herein, electrochemical interface engineering is developed for the rational synthesis of Cu-modified CoCu layered double hydroxide heterostructural nanosheets on carbon cloth (Cu@CoCu LDH/CC). The membrane electrode assembly (MEA) NO₃RR||EGOR electrolyzer confirms the promising performance of Cu@CoCu LDH/CC with maximum FEs of formate and NH₃ (98.1%/98.6% at 1.3 V), a high yield of NH₃ (0.793 mmol h^–1 cm^–2 at 1.6 V), and stability over 120 h at 1.3 V, which outperforms the other reported coelectrolysis systems. In situ spectroscopy reveals the favorable formation of key reaction intermediates and catalytic active species, while the theoretical calculations confirm the optimized electronic structure and energy barriers of both the NO₃RR and EGOR by constructing a Cu@CoCu LDH heterostructure, leading to its high intrinsic activity. Our work offers a promising strategy to develop advanced electrodes for coelectrosynthesis of value-added chemicals from the upcycling of nitrate wastewater and waste plastics.

A comparison of state-of-the-art catalysts for low temperature aqueous phase reforming (APR) of methanol is presented. To facilitate future applications, catalyst tests under two standardized sets of reaction conditions are proposed.

Nitrate ion is a common pollutant in surface and groundwater. Hence, its catalytic conversion into ammonia at ambient conditions by electrochemical and photoelectrochemical pathways is an attractive alternative to current ammonia production from the energy-intensive and high-carbon-featuring Haber-Bosch process. As such, developing highly active and product-selective catalysts with good durability and cost-effectiveness is highly desired. In this work, exfoliated MoS_2-x is reported as a highly active and selective electrocatalyst and a photoelectrocatalyst for nitrate reduction to ammonia. Exfoliation via the acid treatment of bulk MoS₂ results in exfoliated MoS_2-x, which is only a few layers thick and has a high degree of sulfur vacancies (ca. 12−13%). Electrochemical studies and electrolysis product analysis reveal promising nitrate reduction activity, which is found to be highly enhanced by the application of visible light illumination. The exfoliated MoS_2-x achieves a Faradaic efficiency of 69% with an ammonia yield rate of 5.56 mmol g_cat^–1 h^–1 in the absence of a light source, which is enhanced to 80% with an ammonia yield of 7.48 mmol g_cat^–1 h^–1 upon visible light illumination. DFT calculations support the binding of nitrate and other NO_x species to the sulfur vacancies, resulting in the formation of *N, which is then reduced to ammonia.

A Rh(III)-catalyzed sequential C–H bond addition to dienes and in situ formed aldimines was developed, allowing for the preparation of otherwise challenging to access amines with quaternary centers at the β-position. A broad range of dienes were effective inputs and installed a variety of aryl and alkyl substituents at the quaternary carbon site. Aryl and alkyl sulfonamide and carbamate nitrogen substituents were incorporated by using different formaldimine precursors. Moreover, the in situ formed N-Cbz aldimine from ethyl glyoxylate provided β,β-disubstituted α-amino esters with high diastereoselectivity. Two rhodacycle intermediates along the catalytic cycle were isolated and characterized by X-ray structural analysis, and the equilibria between the rhodacycle species in the presence of different reactants were determined. Deuterium labeling studies provided additional information to explain the uncommon 1,3-addition selectivity to the conjugated diene. Density functional theory calculations were consistent with the equilibria determined between the rhodacycle intermediates in the presence of different reactants and provided further insight on the transition state structures and energies for key steps in the catalytic cycle.

The site-selective functionalization of carbon(sp³)–hydrogen bonds in saturated amines remains a persistent challenge owing to their intrinsic electronic deficiency, particularly in activating the α and β positions simultaneously for annulation reactions. Herein, we report a copper(I)-catalyzed dehydrogenation and [2 + 3] cycloaddition of commercially available amines with diaziridinone, which facilitated the direct synthesis of highly valuable imidazolidone derivatives. Operationally simple methodology has a broad substrate scope and convenient scalability, providing an effective and complementary platform for the rapid incorporation of N-heterocycles into amine molecules. Furthermore, comprehensive mechanistic investigations and computational studies indicated the pathway of the radical-type hydrogen atom transfer and [2 + 3] cycloaddition, which were promoted by a four-membered copper(III) species.

Developing low-cost electrocatalysts with high current density (≥1000 mA cm^–2) and long-term durability (≥1000 h), especially at low overpotentials (<300 mV), is essential for sustainable hydrogen (H₂) production on a large-scale via alkaline water/seawater splitting. Along the way, numerous innovative ideas have been proposed to design high-performance transition metal (TM)-based electrocatalysts that meet the requirements of industrial applications. To promote development from laboratory to commercial use in this promising field, it is of great significance to summarize and organize the accumulated knowledge in time. This review begins with the fundamentals of alkaline freshwater/seawater electrolysis, providing theoretical guidance for the design of high-performance electrocatalysts. Special attention is given to effective strategies for enhancing intrinsic activity, extending stability, and improving corrosion resistance of TM-based electrocatalysts. Finally, individual perspectives on future opportunities and challenges are highlighted.

Supporting ligands limit the degree of electrophilic activation for any substrate because they also reduce the Lewis acidity of the transition metal ion. Here, we temporarily mask the Lewis acidity of dicationic Pd(II) by using “shapeshifting” bidentate pyrimidine/olefin ligands L1 and L2. These ligands delocalize/relocalize charge via reversible C–N bond formation. So, although ligated dicationic Pd compounds [1]²⁺ and [2]²⁺ appear charge separated (distributed across Pd and ligand), they react comparably to a solvated Pd(II) dication. Despite reacting like strong Lewis acids, the complexes are tolerant of polar functional groups (Lewis bases that often inhibit electrophilic catalysis). We propose that this property originates from the installation of a more nucleophilic (charge separated) state. This case study suggests that catalysts featuring reversible dynamics can be advantageous relative to their structurally static counterparts.

Uridine/guanosine diphosphate-mannose (UDP/GDP-Man) is the major mannosyl donor in producing mannose-containing oligo/polysaccharides. Its acquisition is greatly limited by its complex and costly synthetic process, which requires multiple substrates and enzymes. The natural UDP/GDP-glucose 2-epimerase functioning C2 epimerization between UDP/GDP-Glc and UDP/GDP-Man remains unreported which is the main hurdle to realize concise production of UDP/GDP-Man. Here, the UDP-glucose 2-epimerase (Glc2E), which behaves like a naturally evolved enzyme, is created and exhibits high-efficient catalysis in producing UDP-Man. Multidimensional engineering, including redesigning the nucleobase recognition region, displacement of the substrate tunnel entrance, and expansion of space for sugar ring rotation, is employed to develop Glc2E from CDP-tyvelose 2-epimerase. Glc2E converts 55.63% of UDP-Glc to UDP-Man, a trace value for the initial enzyme, stTyvE, and its aptitude for GDP-Glc epimerization evolves from unobserved activity to 23.94% conversion. Coupling sucrose synthase with Glc2E achieves the theoretical synthase–epimerase route for UDP/GDP-Man production from inexpensive sucrose. The space-time-yield of UDP-Man is maximized to 8.05 g/L/h within 2.5 h, with a final titer of 22.54 g/L, demonstrating competitive application potential. Moreover, the GDP-Man is synthesized successfully at a titer of 3.49 g/L. Our work inspires the enzyme engineering for epimerases and glycosyltransferases that catalyze nucleotide sugars. The application of Glc2E in the synthase–epimerase route unlocks a concise and feasible synthetic approach for producing cost-competitive mannosyl donors.

Electrochemical promotion of catalysis (EPOC) or non-Faradaic electrochemical modification of catalytic activity (NEMCA) is a general phenomenon in heterogeneous catalysis that in situ controls reaction rates of thermal catalysts via the application of electrical potential and enables supply/removal of ionic species (promoters) from the electrolyte. In this work, we investigated electrochemical promotion by Li-ion for carbon monoxide oxidation and reverse water gas shift (RWGS) reactions. Nanostructured Pt films (50 and 100 nm thickness) and highly dispersed FeO_x nanowires (d = 10 nm) were deposited on the lithium lanthanum titanate (Li_0.29La_0.57TiO₃, LLTO) solid electrolyte. By applying constant electrical potential/current, the catalytic reaction rates for both CO oxidation and RWGS were modified in a non-Faradaic way due to Li-ion migration to/from Pt and FeO_x catalysts, as evidenced by STEM, XRD, and XPS. For CO oxidation, the reaction rate over FeO_x decreased permanently under positive polarization, returning to the initial state only under negative polarization. Pt films showed similar rate decreases upon positive polarization but experienced an immediate increase after returning to the open circuit. For RWGS, positive polarization over FeO_x led to permanent electrochemical promotion with the rate increasing in the H₂-rich environment and decreasing under CO₂-rich conditions. Pt catalysts showed rate increases under all conditions. These differences suggested that FeO_x reacted with Li-ion in the presence of electrons due to its redox activity, while Pt remained chemically stable and did not exhibit similar interactions. Cyclic voltammetry (CV) provided insights into the interaction of Li⁺ with the catalyst and its influence on electrochemical reactions.

NiMo-based alloys and NiFe layered double hydroxides (NiFe-LDHs) are the most promising nonprecious-metal electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) under alkaline conditions. However, the ready leaching of Mo and Fe during electrolysis may cause dynamic variation of the surface composition and structure of the catalysts. Here, we developed a NiMoFe heterostructure consisting of NiMoFe alloy and MoO₄^2–-intercalated NiFe-LDH (NiMoFe HI), which enables self-optimization of HER and self-healing of OER through the dynamic exchange of MoO₄^2– species. During the HER process, the leaching and readsorption of MoO₄^2– optimizes the electronic structure of NiFe-LDH, facilitating H₂O adsorption and dissociation. Simultaneously, the repulsion of OH^– by accumulated MoO₄^2– in the electric double layer can more rapidly drive the transfer kinetics of *OH + e ⇌ OH^– to promote the desorption of *OH from the active sites, thus continuously enhancing the HER activity. During the OER process, the dynamic equilibrium of MoO₄^2– facilitates the readsorption of active Fe(OH)_x species on the NiFeOOH surface and reduces the energy barrier of the OER rate-determining step, achieving self-healing of the OER activity. Benefiting from the self-optimization and self-healing properties for HER and OER, NiMoFe LDH exhibits promising performance in alkaline water splitting, with a low cell voltage of 1.528 V at 10 mA·cm^–2 and stable operation at a high current density of 100 mA·cm^–2 for 150 h.

Alcohol dehydrogenation catalysts in an aerobic atmosphere are often inspired by biological cofactors, which play a major role in controlling the redox chemistry. A large body of work mimicking quinone-containing cofactors established two major mechanistic routes, addition–elimination or transamination. Both of these pathways are completely regulated by two-electron processes, despite the possibility of the cofactor motif being reduced by one electron. In stark contrast to the established mechanisms, we demonstrate a one-electron pathway in quinone catalysis toward dehydrogenating alcohols. The described pyrene dione molecule is efficient in catalytic dehydrogenation of primary, secondary, and aliphatic alcohols. The process starts with the photoexcitation of the dione motif which becomes photoreduced by KO^tBu to generate a persistent semiquinonate radical. The substrate alcohol interacts with the quinone backbone to forge a hydrogen-bonded intermediate, which leads to a crucial hydrogen atom transfer (HAT) step, to accomplish the dehydrogenation reaction. A series of kinetic experiments including Bell–Evans–Polanyi correlation with the bond dissociation enthalpy firmly establish HAT to be rate-determining during dehydrogenation reactions. A kinetic isotope effect measured for the dehydrogenation process at 30 °C is 7.7 ± 0.9. Interception of a series of intermediates by a radical quencher in conjunction with a radical-probe substrate further affirms the radical-mediated, one-electron pathway to be operative that is in striking contrast to two-electron-driven quinone catalysis established so far.

Ene reductases (EREDs) are enzymes that catalyze the asymmetric reduction of C═C bonds. EREDs are potentially useful in the large-scale synthesis of pharmaceutical compounds, but their application as biocatalysts is limited because they are often unstable under process conditions. Previous work addressed this limitation by identifying stabilized EREDs with ancestral sequence reconstruction (ASR), a bioinformatic method that predicts evolutionary ancestors based on a set of homologous sequences. In this work, we sought to apply ASR to design enzyme libraries and leverage machine learning to predict the most stable library variants. We generated an ERED library that targeted residues based on uncertainty in the ASR prediction. Screening data from a portion of the library were used to build a machine learning model that could accurately predict variants with improved thermostability. The most stabilized enzyme outperformed the wild-type and ancestral parent enzymes under process-like conditions with a panel of substrates. We envision that the combination of ASR and machine learning could be generally applied to other classes of enzymes, facilitating the development of high-quality industrial biocatalysts.

Efficient and selective arene hydroxylation under mild reaction conditions is a challenging task in chemical transformation. To achieve this goal, one of us recently reported an experimental breakthrough of a highly efficient iron catalyst based on the sulfur-containing ligand BCPOM. However, the exact mechanism underlying this promising biomimetic catalysis remained elusive. Herein, based on density functional theory modelings combined with experimental results, we successfully revealed an unexpected mechanism of this biomimetic arene hydroxylation. In this mechanism of diiron/BCPOM, the disulfide group of the ligand was found to assist the O–O cleavage of the peroxo species by concomitantly forming an S–O bond, which thus generated an uncommon diferric diiron-oxo intermediate as the real oxidant for the subsequent arene hydroxylation. In this way, the revealed hydroxylation mechanism with diiron/BCPOM differs not only from the mononuclear heme enzyme P450 but also from the diiron nonheme enzyme T4MO substantially. Consistent with the NIH shift experimental results, this mechanism also enabled the experimentally confirmed regioselectivity prediction for some substrates unexplored previously. The unexpected role played by the sulfur-containing ligand in assisting the O–O cleavage by forming the S–O bond further expands our knowledge on how sulfur can facilitate the iron-catalyzed reactions.

Industrial-scale photocatalytic H₂ production from H₂O is a forward-looking aim in research and technology. To this end, understanding the key properties of TiO₂ as a reference H₂ production photocatalyst paves the way. Herein, we explore the TiO₂ nanosize limits, in conjunction with the TiO₂(B) nanophase, as a strategy to enhance the photocatalytic H₂ production at >150 mmol/g/h. We present a targeted engineering realm on the synthesis of quantum dots (QDs) of TiO₂ consisting of an anatase core (3 nm) interfaced with a nanometric shell of the TiO₂(B) phase, synthesized through a modified flame spray pyrolysis (FSP) process. The {TiO₂-anatase/TiO₂(B)} core–shell QDs, with high specific surface area SSA = 360 m²/gr, achieve a milestone H₂ production yield of 156 mmol/g/h and solar-to-H₂ efficiency n_STH = 24.2%. We demonstrate that diligent control of the TiO₂-anatase/TiO₂(B) heterojunction, in tandem with lattice microstrain, are key factors that contribute to the superior H₂ production, i.e., not only the high SSA of the QDs. At these quantum-size limits, the formation of lattice dislocations and interstitial Ti centers enhances photon absorption at ∼2.3 eV (540 nm), resulting in the generation of midgap states around the Fermi energy. EPR spectroscopy provides direct evidence that the photoinduced holes are preferentially localized on the TiO₂(B) shell, while the photoinduced electrons accumulate on the anatase nanophase. Combined electrochemical and photocatalytic analyses demonstrate that the presence of an optimal TiO₂(B) phase is significant for the photoactivity of TiO₂ in all QD materials. High SSA does contribute to enhanced photocatalytic H₂ production; however, its role is not the key-determinant. TiO₂ lattice-dislocations in QDs provide extra DOS that can additionally assist in the photon utilization efficiency. Overall, the present work reveals a general concept, that is, at the quantum-size scale, lattice microstrain engineering and interstitial-states' formation are spontaneously facilitated by nanolattice physics. Diligent optimization of these properties offers a pathway toward high-end photocatalytic efficacy.

The asymmetric addition of allylic boronates to electrophiles is a powerful method for preparing chiral molecules bearing synthetically valuable allylic moieties. While effective catalytic methods exist, they have so far been limited to the enantioselective allyl- and crotyl-boration of carbonyl compounds and imines, thereby forming C–C bonds. Here, we present a strategy that expands the scope of this catalytic asymmetric platform to include the stereoselective formation of C–N bonds. We have identified an inexpensive and readily available chiral diol that catalyzes the addition of allylic boronates to azodicarboxylates, affording chiral allylic hydrazides with high stereocontrol. This electrophilic amination chemistry shows a broad substrate scope and requires mild conditions, proceeding at ambient temperature. Mechanistic studies reveal that the chiral diol catalyst facilitates the formation of a chiral allylic boronate through the reversible exchange of the boron’s achiral alkoxy ligand. By coordination with the electrophilic azodicarboxylate, the substrates mutually activate each other, allowing for the stereoselective transfer of the allyl group.

As one of the cleanest fossil fuel resources, methane is also the second largest greenhouse gas after CO₂ owing to its strong greenhouse effect. The direct emission of large quantities of trace and unburned methane causes a serious energy loss and greenhouse effect. Catalytic methane combustion is a promising strategy in eliminating methane slip to address the urgent environmental issue. However, the current methane abatement catalysts still face great challenges in thermal stability, water resistance, and sulfur tolerance. In this review, we focus on the popular noble metal-based catalysts, discuss the distinct reaction mechanisms including the Langmuir–Hinshelwood model, Eley–Rideal model, Mars–van Krevelen model, and two-term mechanisms. The deactivation mechanisms induced by sintering, sulfur, and water on popular Pd-based catalysts are then analyzed. Then, we outline the promotion strategies from two aspects, i.e., construction of a core–shell structure and electronic engineering of the active phase to improve thermal stability and poisoning resistance. Finally, a summary and prospects with an emphasis on the newly developed oxide-metal interfaces and photothermal catalysis for highly efficient methane combustion are addressed.

A metal–insulator–semiconductor (MIS) structure is an attractive interfacial structure for efficient photoelectrochemical (PEC) water-splitting reactions. However, developing a cost-effective and highly active photoelectrode for the PEC water-splitting reaction is still a major challenge. In this study, we use an easy-to-operate and economical UV/ozone (UV/O₃) oxidation process to prepare ultrathin SiO_x oxide as an insulating layer, which is integrated with the bilayer non-precious-metal collector Al/Ni serving as the catalyst and the p-Si semiconductor to obtain a cost-effective and efficient MIS structure photocathode. The outcomes demonstrate that the ultrathin SiO_x insulation layer significantly improves the PEC hydrogen evolution reaction (HER), through comparing the photovoltage and photocurrent density of the MIS system. The inner metal Al in the bilayer collector Al/Ni regulates the degree of band bending at the semiconductor–metal interface. Additionally, the presence of the ultrathin Al₂O₃ insulation layer effectively reduces Fermi-level pinning, which promotes the efficient transfer of photoelectrons to electrolytes. These were confirmed through photoelectric performance testing of the MIS system. The generation of a photocurrent of 15 mA cm^–2 at a potential level of 0 V (vs reversible hydrogen electrode) has been obtained by optimizing the thickness of the SiO_x and bilayer non-precious-metal collector. This study presents an economical and efficient strategy for enhancing PEC-HER performance in silicon-based photocathodes using an MIS structure.

A series of shape-persistent bis-[C(sp³)-chelating] Ti₂ (plus Zr₂ and Hf₂) complexes with a rigid linker component (xanthene or dibenzofuran) are presented. These structurally diverse assemblies display limited yet different conformational flexibility, and crucially, such geometric constraints confer access to a range of intermetallic separations and orientations to potentially enhance catalytic activity and cooperative effects. For ethylene polymerizations, the Ti₂ catalysts (in conjunction with trityl borate) exhibit greater efficiencies and produced polymers with higher M_w than mononuclear controls, which is significant considering the more crowded environment for cofacial bimetallic sites. Proficient 1-hexene incorporations were observed for ethylene-(α-olefin) copolymerization reactions. The F-substituted m-aryl/dibenzofuran-linked catalyst (5), which is revealed by NMR analysis to be conformationally dissimilar to its F-absent congener, produced copolymers with higher M_w and elevated 1-hexene incorporation levels (up to 44%), when compared with its mono-Ti control (19%). These results suggest that catalyst frameworks with suitably adjustable conformations and Ti···Ti distances can facilitate bimetallic enchainment interactions with α-olefin substrates and their insertion.

Benzo[b]phosphole oxides are important P-heterocycles that find applications in optoelectronics due to their inherent photophysical properties. Traditional routes for the synthesis of such molecules from readily available precursors require stoichiometric amounts of transition metal salts, bases, oxidants, and additives, thereby lacking efficiency. Photochemical pathways still need a terminal oxidant to complement the photocatalytic cycle, whereas electricity may be a viable oxidant. Hence, photoelectrochemistry (PEC), combining photocatalysis and synthetic organic electrochemistry, was used to simplify the synthetic protocols. We use the potency of 4CzIPN for the consecutive P–H/C–H bond functionalizations for preparing benzo[b]phosphole oxides from secondary phosphine oxides and nonactivated internal alkynes with up to 93% yields and with good functional group tolerance. Detailed mechanistic investigations confirm an intermolecular electron transfer between 4CzIPN and aryl secondary phosphine oxides upon photoexcitation. The photocatalyst is regenerated by anodic oxidation.

The production of syngas from light hydrocarbons is a viable way of converting under-utilized hydrocarbon sources into valuable products until a full transition to renewable energy sources is achieved. However, current heterogeneous catalysts for syngas production suffer from deactivation, either by coking or oxidation. Here, we report on the behavior of model nickel catalysts within the context of ethylene partial oxidation and observe the catalyst-environment interaction as a function of reactant feed and temperature. Using a combination of operando microscopy and spectroscopy and focusing on a reaction regime characterized by synchronized self-sustained oscillatory dynamics, we are able to gain additional insights into the dynamic interplay between reactive species and active catalyst surfaces of varying reactivity. Real-time secondary electron imaging coupled with online mass spectrometry and thermal data shows that the oscillatory behavior is characterized by a highly active half-period during which the surface of the nickel catalyst is metallic and a less active half-period during which the surface is oxidized. Complementing the direct surface imaging, operando X-ray photoelectron spectroscopy provides missing information about the alternating chemical state of the catalyst surface in the oscillating reaction regime. It reveals that changes in the gas phase composition (C₂H₄/O₂ ratio) alter the population of reaction intermediates (e.g., carbides) on the nickel surface, which in turn drives the selectivity of the reaction toward different products. The observed chemical dynamics involve changes in gas-phase composition, rate-dependent heat of reaction, the chemical state of the catalyst, and the formation of reaction products, all of which are interconnected. Ultimately, the complex oscillations and catalytic behavior are attributed to a multistep mechanism that involves complete ethylene oxidation, dry and wet reforming of ethylene, and the reverse water gas shift reaction.

An extended microkinetic model (MKM) for the selective oxidation of ethylene to ethylene oxide (EO) is presented, based on an oxidic representation of the silver (Ag) surface, namely, the p(4 × 4) oxidic reconstruction of the Ag(111) phase to mimic the significant oxygen coverage under reaction conditions, as is evidenced by recent operando spectroscopic studies. The MKM features three pathways each for producing either ethylene oxide (EO) or carbon dioxide (CO₂), including the common intermediate or oxometallacycle (OMC) pathway, an atomic oxygen pathway, as well as pathways centered around the role of a diatomic oxygen species occupying an oxygen vacancy (O₂/O*). The MKM uses a composite set of experimental and density functional theory (DFT) kinetic parameters, which is further optimized and trained on experimental reaction data. A multistart ensemble approach was used to ensure a thorough sampling of the solution space, and a closer analysis was performed on the best-performing, physically meaningful solution. In agreement with published DFT data, the optimized MKM observed that the OMC pathway heavily favors the total combustion pathway and alone is insufficient in explaining the ∼50% EO selectivity commonly reported. Furthermore, it confirmed the pivotal role of the O₂/O* species in the flux-carrying pathways for EO production. The MKM additionally highlights the fluctuating nature of the catalyst surface, in that the proportion of metallic to oxidic phase changes according to the reaction conditions, accordingly resulting in kinetic implications.

Electrochemical nitrate reduction (NO₃^–R) presents a promising pathway for carbon-neutral ammonia (NH₃) synthesis. Enhancing NH₃ selectivity through a tandem process can be achieved by combining Cu with a secondary metal, which allows for an adjustable binding energy between the bimetallic catalyst and key nitrogen intermediates. Herein, we developed a biphasic Ag–Cu heterostructure with a controllable elemental composition, which significantly improved NH₃ production through tandem NO₃^–R. In-situ infrared spectroscopy and finite element simulations revealed that Ag serves as the active site for converting NO₃^– to NO₂^–, leading to a high localized concentration of NO₂^–, which is subsequently reduced to NH₃ on adjacent Cu sites. Density functional theory calculations further confirmed the critical role of the Ag–Cu biphasic interface in promoting tandem NH₃ production. This work offers valuable insights into the tandem NO₃^–R pathway in bimetallic heterostructures, providing a foundation for optimizing catalysts and advancing large-scale sustainable NH₃ synthesis.

Two-dimensional metal-containing covalent organic frameworks (COFs) have been employed as electrocatalysts. However, the metal sites were stacked within the layers with strong interactions, which hindered mass transport to them in the catalytic process. Herein, we constructed a pore-confined catalyst in a vinylene-linked COF for the oxygen reduction reaction (ORR) via the Katritzky reaction. By anchoring the catalytic sites along the pore walls with covalent bonds, the catalytic units were well-exposed during the catalytic process and retained crystallinity and porosity, facilitating mass access to the metal sites. In addition, the electron/charge transported from the framework to the metal units modulated the electronic states, thus improving the catalytic activity. The catalytic COF exhibited a half-wave potential of 0.85 V and a mass activity of 109.7 A g^–1, which are better than those of other reported COFs. Theoretical calculations revealed that the interaction between the framework and metal sites contributed to the easy formation of OOH* and OH*, resulting in high activity. This work provides insights into designing catalytic COFs based on C═C linkages.

Precisely designing the atomic coordination structure of the catalytic center is highly desired to lower the energy barrier of CO₂ photoreduction. The present work shows that engineering Nb single atom coupled Bi–O vacancy pairs (V_Bi–O) into Bi₂₄O₃₁Br₁₀ (BOB) atomic layers can create a preferential local asymmetric structure. This configuration can result in a stronger local polarization electric field and thus prolong the carrier lifetime, as proved by ultrafast transient absorption spectroscopy. Meantime, this unique Nb SA-V_Bi–O associate favors the formation of strong chemical interaction between key *COOH intermediate and catalytic center, thus lowering the energy barrier of the rate-limiting step. Benefiting from these features, a high CO generation rate of 76.4 μmol g^–1 h^–1 for CO₂ photoreduction can be achieved over Nb SA-V_Bi–O BOB atomic layers in pure water, roughly 5.4 and 92.7 times higher than those of BOB atomic layers or bulk BOB, respectively. This work discloses an important paradigm for designing single atom coupled defect associates to optimize photocatalysis performance.

Pt-based catalysts have been widely used for propane dehydrogenation to propene. However, the high reaction temperature generally induces serious sintering and agglomeration of metal species, thus leading to rapid deactivation of the catalysts. Herein, PtIn nanoclusters (NCs) encapsulated in hollow-structured silicalite-1 (designated as PtIn@S1–H) was prepared using recrystallization method. This material shows high catalytic performance in propane dehydrogenation. The propane conversion and propene selectivity reach ∼45–47.5% and ∼99%, respectively, at 547 °C at least within 167.6 h. As a result, it displays a significantly higher specific activity for C₃H₆ formation (0.37–0.59 s^–1) than Pt@S1, Pt@S1–H, and other reported Pt-based catalysts. Notably, its catalytic performance is well maintained for more than 3600 h, with propane conversion of ∼31–34% and propene selectivity of ∼91–95%, when pure propane is fed. More interestingly, this catalyst can be reused through regeneration. EXAFS, HAADF-STEM and DFT calculation, and AIMD simulation results show that hollow-structured silicalite-1 crystal morphology not only facilitates the formation of Pt₅In₃ alloy NCs but also inhibits NC aggregation and growth. PtIn@S1–H showed a TON ≥ 38996 in contrast to 5367, 4928, 798, and 542 obtained on PtIn@S1, PtSn@S1, PtSn/Al₂O₃, and PtIn/Al₂O₃, respectively, if the catalysts were considered to be deactivated when the propane conversion was decreased by 15%. This is because alloying of In into Pt NCs weakens the interaction of C₃H₇* intermediates with metallic Pt NCs and the adsorption of C₃H₆ on the catalyst surface, thus suppressing the C₃H₇* cleavage reaction and enhancing propane activation and propene selectivity.

We demonstrate an efficient, scalable, and stereoselective C-glycosylation with thioglycosides possessing a unique photoactive tetrafluoropyridin-4-yl (TFPy) thio radical leaving group, affording editable and medicinally and biologically essential C-α-glucogallin derivatives. In the presence of silyl enol ether acceptors, the desulfurative coupling reaction performs smoothly under mild conditions upon exposure to blue light irradiation. This versatile protocol permits the synthesis of sugar-drug chimeras by C1 ketonylation of complex drug-derived silyl enol ethers. The scale-up synthesis, anomeric epimerization, and post-C-glycosylation modification of ketone sugars showcase the reaction’s potential utilities. Furthermore, the reaction could be applied to direct carbohydrate skeleton editing by equipping the leaving group on the nonanomeric position. The ketonylation is viable for unprotected TFPy thioglycoside, affording a direct route to unprotected ketonyl sugars. The concise six-step assembly of both configurated C-glucogallins from commercially cheap glucose pentaacetate and their antioxidant reactivity investigations underline the promising medicinal relevance of our current protocols. The reaction mechanism was investigated through a radical trapping experiment, an oxocarbenium trapping experiment, a fluorescence quenching experiment, and Stern–Volmer analysis, confirming that the major glycosyl radical intermediates are generated from the thioglycoside donors, whose tetrafluoropyridin-4-yl thio group could effectively quench the fluorescence of excited Ir(ppy)₃ through an oxidative quenching process, and C-glycosylation with oxocarbenium is a complementary route to the product, accounting for examples with moderate selectivities.

The investigation into the synthesis of azabicyclo[3.1.1]heptanes (azaBCHeps) as bioisosteres to flat aza-aromatics has garnered increasing attention, while it encounters significant challenges. Herein, we have demonstrated the In(OTf)₃-catalyzed (3 + 3) dipolar cyclization of bicyclo[1.1.0]butanes (BCBs) with hydrazones and π-allyl-iridium 1,3-dipoles, engendering a diverse array of azaBCHeps. The cyclization of hydrazones and BCBs furnished densely substituted 2,3-diazabicyclo[3.1.1]heptanes and 2,3-diazabicyclo[3.1.1]heptenes under nitrogen and oxygen atmospheres, respectively. A combination of experimental and computational investigations lends robust support for the proton-transfer-interposed sequential mechanism. More importantly, by integrating In(OTf)₃/iridium relay catalysis, enantiopure 2-azabicyclo[3.1.1]heptanes were constructed through the (3 + 3) cyclization of BCBs with aza-π-allyl-iridium 1,3-dipoles, in situ generated from N-allyl carbonates. Both methodologies exhibit mild reaction conditions and good tolerance for various functional groups. Moreover, the copious derivatization of products highlights the utility of the newly synthesized heterobicyclic motifs as versatile building blocks in synthetic chemistry.

It has been a challenging task to clearly elucidate various structural features and how their interactions affect the photocatalytic hydrogen production performance. In this work, various factors, including crystallinity, specific surface area associated with morphology, energy band gap and energy levels, surface charge, and hydrophilicity, were employed to investigate the structure–property–activity correlations of β-ketoenamine-linked covalent organic framework (TpPa-1-COF) for photocatalytic H₂ production, which could influence the light harvesting, charge separation and transfer, and surface catalytic active sites. By using different methods to prepare TpPa-1-COFs, we can regulate these influencing factors to investigate their relationship with activity. It is found that the TpPa-1-COF prepared by a molecular organization method (labeled as TpPa-1 (MO)) exhibits the highest photocatalytic H₂ evolution activity compared with the TpPa-1-COF samples prepared by solvothermal methods using acetic acid (HOAc) as a catalyst (TpPa-1 (ST-HOAc)) and KOH solution as a catalyst (TpPa-1 (ST-KOH)), which is associated with the highest crystallinity, the optimal energy levels, the largest BET-specific surface area, and the best hydrophilicity for TpPa-1 (MO). Moreover, our findings suggest that the enhanced total photocatalytic H₂ evolution efficiency (η_total) of TpPa-1 (MO) may be mainly attributed to the efficient separation and migration of photogenerated charges (η₂) and the vibrant surface catalytic active sites (η₃). Overall, this work provides some deep insights into the structure–property–activity relation of TpPa-1-COF photocatalysts, which offers valuable inspiration and guidance for the thoughtful design of COF-based photocatalysts for H₂ evolution.

High-entropy oxides (HEOs) are potential electrocatalysts for overcoming the sluggish kinetics of the oxygen evolution reaction (OER). Conventionally, the thermodynamic barrier of the lattice oxygen mechanism (LOM) is lower than that of the adsorbate evolution mechanism (AEM). However, controlling the transition from the AEM to the LOM remains challenging. Herein, an in situ modulation strategy has been developed to synthesize N-FeCoNiAlMoO_x by introducing structural directing agents and electronic modulators. Different instruments were used to identify the nitridation-triggered micromorphologies and phase transformations. X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure spectroscopy (XAFS) reveal the optimized electronic structures after nitrogen doping. N-FeCoNiAlMo_x exhibits OER performance with low overpotentials of 240 and 285 mV at 10 and 100 mA·cm^–2, respectively. pH dependence, free-radical capture experiments, and density functional theory (DFT) calculations confirm that nitrogen doping facilitates the LOM pathway. This work elucidates nitrogen’s critical role and the LOM pathway’s contribution to efficient OER performance.

Nitrile-containing natural products, despite being a limited group of secondary metabolites, display remarkable structural and functional diversities. Aldoxime formation represents a crucial step in nitrile installation via the aldoxime-nitrile pathway although structural information regarding aldoxime formation is extremely limited. Here, we report the isolation of a nitrile compound 6-dimethylallylindole-3-acetonitrile (6-DMAIAN) and identify the aldoxime-forming enzyme gene diatB as a robust reporter for bacterial nitrile biosynthesis. We characterize the flavin-dependent monooxygenase DiatB and provide structural and mechanistic insights into the structural parameters dictating its substrate compatibilites. This enzyme initiates a nucleophilic attack on the amino group of the substrate 6-dimethylallyl-l-tryptophan (6-DMAT), resulting in formation of a transient aldoxime that precedes nitrile installation. Moreover, the DiatB recognition motif is elucidated shedding light on its substrate flexibility. We also apply bioinformatics analysis to examine the distribution and diversity of functional DiatB homologues across an array of potential nitrile-forming organisms. Given the activity of DiatB and its prevalence in secondary metabolite biosynthesis, our results provide important insight into what is, arguably, the most crucial and pivotal step in nitrile biosynthesis; these findings also suggest a promising enzymatic tool for nitrile drug design.

Kinetic interconnectivities of methanol oxidative dehydrogenation and dehydration are manifestation of the underlying thermochemical/electronic correlations between redox and Brønsted sites on bifunctional Keggin-type polyoxometalate (POM) phosphomolybdic acid clusters with their electronic properties perturbed by sodium cation exchange (H_xNa_3–xPMo, x = 3–0). As sodium exchange increases, activation free energies for the elementary C–H scission in methanol oxidative dehydrogenation, occurring at isolated redox sites (O*) or Brønsted acid-redox site pairs (OH/O*), and for the first-order C–O formation in methanol dehydration, occurring at Brønsted sites, increase proportionally within 10–11 kJ mol^–1 at 433 K, while their activation enthalpies exhibit an inverse correlation. A Born–Haber thermochemical analysis reveals the reasons behind the site interconnectivities by establishing their respective kinetic-thermochemical relationships. The kinetically relevant C–H scission involves a late transition state, either [HOCH₂···H···O*]^‡ at O* or [OH···HOCH₂···H···O*]^‡ at OH/O*, with the transfer of an electron (e^–) and a proton (H⁺) as an H atom (H•) from the methyl fragment to redox sites, where hydrogen addition energy (HAE), comprising the negative electron affinity (−EA_POM) and proton affinity (−PA) of POM clusters, is a kinetic descriptor. The parallel methanol C–O formation features a late carbocationic transition state, [(CH₃OH···CH₃⁺···H₂O)···POM^–]^‡, involving proton transfer from POM clusters to adsorbed methanol species, where the deprotonation energy (DPE) of the Brønsted site serves as a kinetic descriptor. Notably, hydrogen addition energy decreases by ∼23 kJ mol^–1, while deprotonation energy increases by 80–230 kJ mol^–1, as sodium exchange increases. This slight negative thermochemical correlation arises from the inherent opposing proton transfers during redox (−PA) and Brønsted acid catalysis (DPE), modulated by the energetic effect of electron transfer (−EA_POM) upon sodium exchange on H_xNa_3–xPMo clusters (x = 3–1). The mechanistic interpretation and framework established here explicitly correlate the kinetic, thermochemical, and electronic properties of redox and Brønsted sites, offering insights into their intrinsic reactivity couplings, and are applicable to other bifunctional catalysts.

Electrocatalysts capable of working efficiently in acidic media for the oxygen evolution reaction (OER) are highly demanded for the large-scale utilization of proton exchange membrane (PEM) water electrolysis. This study focuses on the design and fabrication of cation/oxygen vacancy-enriched RuO₂ catalysts to investigate the impact of defect types on the OER activity and stability of RuO₂. The comprehensive blend of experimental and theoretical approaches elucidates that the presence of Ru vacancies in Ru_1–xO₂ modulates the d-band center and optimizes the adsorption energy of the OER intermediates, thereby augmenting the intrinsic OER activity. Conversely, the presence of oxygen vacancies in RuO_2-x diminishes the strength of Ru–O bonds, suppressing the involvement of the lattice oxygen oxidation mechanism (LOM) and Ru dissolution, consequently enhancing long-term stability. Notably, Ru_1–xO₂ exhibits the lowest overpotential of 212 mV at 10 mA cm_geo^–2, while RuO_2–x demonstrates superior stability, enduring 400 h under 10 mA cm_geo^–2, surpassing many catalysts for acidic OER in the literature. Our findings demonstrate that defect engineering is a promising strategy to achieve electrocatalysts with super catalytic performance in acid media for water electrolysis.

The combination of N-heterocyclic carbene (NHC) organocatalysis with photochemical activation is becoming increasingly established as an approach for conducting radical organic reactions under mild and practical conditions. As comparatively easy to prepare and handle organic compounds, alkyl silanes are attractive substrates for radical chemistry as desilylative mesolysis of the corresponding radical cations is known to be rapid. Here, we report the successful application of benzyl silane derivatives as source of alkyl radicals in dual NHC/photoredox-catalyzed radical–radical coupling reactions with acyl fluorides. Relatively electron-rich benzyl silanes reacted smoothly to afford the corresponding ketones in generally good yields, while optimization of the NHC and photocatalyst allowed for a wider scope including primary benzyl substrates. Furthermore, initial experiments revealed that organosilanes bearing N-, O- and S-heteroatoms can also serve as alkyl radical sources under these conditions.

Optical-magnetic field coupling technology provides an effective avenue for comprehensive enhancement of the overall performance of electrocatalytic reactions. However, this technology requires that the electrocatalysts possess good responsiveness to these fields. Moreover, the underlying mechanism for performance enhancement under an optical-magnetic field is also unknown. Herein, a low-temperature magnetic field-assisted electrodeposition method is reported to synthesize highly crystalline iron hydroxides on a nickel foam (Fe(OH)_x/NF), which enables directed hole and electron transfer under optical-magnetic field-assisted electrocatalysis. The external field-assisted synthesis and directed transfer effects greatly improve the oxygen evolution reaction (OER) performance of the catalyst, reflected in a reduction of 63 mV in overpotential at 10 mA cm^–2 (from 285 to 222 mV) and reliable stability. A new mechanism of “directed charge carrier (electron and hole) transfer” is proposed to elucidate the structural feature and functional enhancement of Fe(OH)_x/NF for achieving the optical-magnetic synergistic effects in the OER process.

The rational design of nanocatalysts with high activity and selectivity is crucial for photocatalytic selective oxidation, where reactive oxygen species (ROS) serve as the key oxidants for inducing molecular catalytic behavior. We developed a defective ZnIn₂S₄/Ti₃C₂ Schottky junction featuring a full-space electric field by chemically anchoring Ti₃C₂ nanoparticles onto the defects of a ZnIn₂S₄ nanosheet via the defect-mediated heterocomponent anchorage approach, as a photocatalyst platform for manipulating the efficient and alternative ROS generation (^•OH or ^•O₂^–) to controllably oxidate the intramolecular alcohol hydroxyl or aldehyde group toward tunable oxygenates. The full-space directionally aligned electric field creates asymmetrical charge distributions, facilitating charge carrier localization and delocalized electron transportation, ultimately leading to an order of magnitude increase in ROS concentration for superhigh activity. Meanwhile, due to their thermodynamic and kinetic advantages under different atmospheres, hydroxyl radicals preferentially activate alcohols and induce two consecutive dehydrogenation reactions, whereas superoxide radicals preferentially activate aldehydes and induce oxygen insertion processes, thereby achieving selectivity control of the products. Encouragingly, several compounds with alcohol hydroxyl and aldehyde groups are compatible using the current protocol. This work provides a paradigm for programmable construction of composite photocatalysts in selective oxidation, elucidating the substantial impact of ROS generation (concentrations and types) on the efficient oxidation of specific functional groups.

Hydrogen peroxide (H₂O₂) is an environmentally friendly oxidant, with production reaching 5.7 million tons by 2028 and a market size of USD 4.04 billion by 2029. Understanding the mechanism of oxygen reduction to H₂O₂ and the structure–activity relations on carbon materials is, therefore, of high significance for the more environmentally friendly synthesis of this important chemical. We have used oriented pyrolytic graphite (PG-edge and PG-basal) and glassy carbon (GC) as model electrodes to investigate the influence of carbon defects, oxygen-containing functional groups, and the presence of alkali metals on the activity and selectivity toward H₂O₂ production under acidic conditions. Electrochemical measurements, such as rotating ring disk electrode and electrochemical impedance spectroscopy, as well as in situ Raman spectroelectrochemistry indicated that PG-basal and GC electrodes preferentially form H₂O₂ as the product through the two-electron pathway via inner and outer sphere mechanisms, respectively. The mechanism is significantly affected by the potential of maximal entropy, which determines the position of species in the solution within the inner or outer Helmholtz plane. The influence of alkali cations (Li⁺, Na⁺, K⁺, and Cs⁺) on the oxygen reduction reaction of these model carbon electrodes was investigated. Large cations, e.g., K⁺ and Cs⁺, showed influence on the reaction intermediates and thus on the electrodes’ selectivity. The present study provides important insights and contributions to the fundamental aspects of hydrogen peroxide production in acidic conditions and further advancements in the development of metal-free carbon-based catalysts.

An atroposelective dynamic kinetic resolution of configurationally labile heterobiaryl ketone N-oxides via Mn-catalyzed asymmetric hydrogenation has been disclosed. By use of a structurally finely tuned chiral ferrocenyl P,N,N-ligand, the hydrogenation proceeds smoothly under mild conditions with simultaneous installation of central and axial chirality, giving a wide range of atropisomeric 1-arylisoquinoline and 2-arylpyridine N-oxides bearing a chiral alcohol structure with high diastereo- and enantioselectivities. The diastereomer of the hydrogenation product could be readily prepared in a stereospecific way with the complete inversion of the central chirality via Mitsunobu reaction. The value of this central- and axial-chiral heterobiaryl N-oxide scaffold is preliminarily demonstrated by its successful utility as a chiral catalyst in asymmetric allylation of benzaldehyde with allyltrichlorosilane.

The photosynthesis of hydrogen peroxide (H₂O₂) from pure water and oxygen using metal-free photocatalysts offers a renewable approach to convert solar energy to storable chemical energy. However, the efficiency of H₂O₂ photosynthesis is often hindered by the rapid recombination of photogenerated charge carriers. Herein, we present an elegantly designed covalent triazine framework (CTF) photocatalyst, denoted as Ace-asy-CTF, with a stepwise electron transfer pathway for the highly efficient photosynthesis of H₂O₂. Notably, Ace-asy-CTF possesses localized excited-state charge distribution and stepwise electron transfer that is created by the weakly conjugated acetenyl units in the asymmetric frameworks, as revealed by transient spectroscopies and further supported by theoretical calculations. Meanwhile, the introduced acetenyl units also serve as active sites for the oxygen reduction reaction (ORR). The simultaneously enhanced stepwise charge transfer and two-step 2e^– ORR in Ace-asy-CTF result in an excellent H₂O₂ yield of 2594 μmol g^–1 h^–1, directly produced from oxygen and pure water without requiring any sacrificial reagents. This work paves the way for the development of next-generation metal-free catalysts, providing a feasible benchmark for the highly efficient and stable photosynthesis of H₂O₂.

Proton-coupled electron transfer (PCET) allows a kinetically favorable pathway for electrochemical conversions. Inspired by this, an electrochemical mediator, N-pyridylferrocenecarboxamide (Fcpy), having site-separated electron and proton transfer sites and its analog are reported. The BDFE of the Fcpy mediator is estimated to be 80.4 kcal mol^–1. As a proof-of-concept study, Hantzsch ester (HE) having a C–H BDFE of 70.70 kcal mol^–1 has been electrochemically oxidized to yield 93% of the desired product. The computational data suggests an ET-PCET-PT process for the mediated HE oxidation with Fcpy. Further, the electrochemical HE oxidation kinetics is recorded for a series of ferrocene derivatives devoid of any Brønsted base and having different E_1/2 and is compared with the Fcpy and its analog. The logarithm (rate) vs E_1/2 for electrochemical HE oxidation shows a clear kinetic advantage for the multisite PCET mediators. Eyring analysis revealed crucial activation parameters for the MS-PCET mediator.

Enzymes’ catalytic promiscuity enables the alteration of product specificity via protein engineering; yet, harnessing this promiscuity to achieve desired catalytic reactions remains challenging. Here, we identified HCinS, a monoterpene synthase (MTPS) with a high efficiency and specificity for 1,8-cineole biosynthesis. Quantum mechanics/molecular mechanics (QM/MM) simulations, which were performed based on the resolved crystal structure of HCinS, revealed the mechanistic details of the biosynthetic cascade reactions. Guided by these insights, in silico HCinS variants were designed with fine-tuned transition-state energies and reaction microenvironments. Three variants (T111A, N135H, F236M), each with one amino acid substitution, exhibited high specificity in the production of monocyclic (R)-α-terpineol, (R)-limonene, and acyclic myrcene, respectively, maintaining over 55% efficiency of native HCinS. These designed HCinS variants surpassed naturally evolved isozymes in catalytic capacity and enabled yeast to achieve the highest microbial titer of each corresponding terpene. Furthermore, the single mutation of four functional equivalent amino acids in other four identified TPSs, respectively, resulted in the expected shifts on product specificity as HCinS variants. This research offers insights into the mechanisms controlling the TPS’s product promiscuity and highlights the universal applicability of computational design in reshaping the product specificity of TPSs, thereby paving innovative avenues for creating enzymes with applications in chemistry and synthetic biology.

Ni-based catalysts are the most promising candidates for methane dry reforming (MDR) reaction but still suffer from deactivation caused by coke-deposition. Herein, we reported a coke resistance MDR catalyst consisting of cationic Ni clusters (Ni^δ+, 0 < δ < 2) stabilized over oxygen-functionalized boron nitride. A simple method was developed for the fabrication of highly dispersed cationic Ni clusters on boron nitride. The local coordination modes between nickel and boron nitride determine the formation of cationic Ni clusters. We provided detailed spectroscopy and microscopy characterizations to reveal the structure features of these cationic Ni clusters. The average particle size of these clusters is ∼1.7 nm. There are abundant Ni_x^δ+–O–B interfaces on the cationic Ni clusters, which serve as catalytically active sites. Compared to conventional metallic Ni nanoparticles, the cationic Ni clusters exhibited comparable apparent catalytic activity and reduced carbon deposition, particularly operated at 600 °C where unavoidable coke formation from CH₄ cracking and the Boudouard reaction usually tends to occur thermodynamically and kinetically. Based on theoretical and experimental evidence, a dynamic synergistic conversion mechanism for CH₄ and CO₂ on the Ni_x^δ+–O–B interface has been revealed. The oxygen within the Ni_x^δ+–O–B interface could rapidly convert CH_x*(x = 1–3) intermediates forming H₂ and CO to avoid carbon deposition. CO₂ is efficiently activated at boron sites of the Ni^δ+–O–B interface to regenerate active oxygen species, thereby boosting the conversion of CH₄. These insights may shine light on the development of intrinsic coke-free Ni-based catalysts for methane dry reforming in the near future.

Enhancing the catalytic activity of photosensitizers is critical for photocatalysis, especially in dual catalytic systems. We present the integration of N-aryl phenoxazine photosensitizers and nickel-bipyridine catalysts into linear and cross-linked polyacrylate matrices, creating robust polymer-supported dual photocatalysts. The linear flexible polymer confers good solubility in organic solvents to ensure efficient interactions between catalytic sites and substrates. The proximity of phenoxazine units and nickel complexes in the linear copolymer P1-Ni boosts electron, energy, and radical transfers, significantly enhancing the catalytic activity of phenoxazine photosensitizers. P1-Ni exhibits high activity in catalyzing visible-light-driven sulfonylation, esterification, and etherification reactions across a broad substrate scope at extraordinarily low catalyst loadings (0.1 to 0.2 mol %) and with exceptionally high turnover numbers approaching 1000. P1-Ni outperforms its homogeneous control by 27- to 38-fold. Additionally, an insoluble cross-linked polymer catalyst (P2-Ni) was synthesized by incorporating a divinyl cross-linking agent. P2-Ni swells in organic solvents, displays activity comparable to that of P1-Ni, and is readily recovered via centrifugal separation and used in six catalytic cycles with minimal loss of activity. This work demonstrates the ability of polymer supports to enhance the activities of organic photosensitizers in photocatalytic organic transformations by facilitating electron, energy, and/or radical transfers.

Hydrogenation of CO₂ to ethanol is an efficient process for the utilization of CO₂ along with the production of value-added chemicals. However, CO₂ hydrogenation to ethanol is a complicated reaction, requiring the catalyst to activate CO₂ efficiently and accurately regulate the C–C coupling to achieve a high ethanol selectivity simultaneously. Herein, we report the synthesis of RhFeO_x catalysts supported on TiO₂ with different crystal phase compositions (anatase, rutile, and P25), which were applied for the selective CO₂ hydrogenation to ethanol. The RhFeO_x/P25 catalyst presented a high dispersion of Rh nanoparticles on the P25 support with abundant Rh⁰–Rh^δ+–O_V–Ti³⁺ (O_V: oxygen vacancy) interfacial sites over the anatase/rutile junction. The optimized RhFeO_x/P25 catalyst exhibited a high ethanol space–time yield of 18.7 mmol g_cat^–1 h^–1 and a high Rh turnover frequency of 544.8 h^–1 with 90.5% ethanol selectivity. An in-depth investigation via various ex situ and in situ characterizations as well as H₂/D₂ exchange and C₂H₄ pulse hydrogenation experiments demonstrated that the Rh⁰–Rh^δ+–O_v–Ti³⁺ interfacial sites played a crucial role in the conversion of CO₂ to ethanol. The surface Rh⁰ sites facilitated the CO₂ activation and hydrogenation, while the Rh⁰–Rh^δ+–O_v–Ti³⁺ interfacial sites boosted the C–C coupling to produce ethanol. The high-performance RhFeO_x/P25 catalyst also provides an attractive route for highly efficient ethanol synthesis via CO₂ hydrogenation.

A promising strategy to enhance exciton dissociation and charge separation in phenolic-polymer-based photocatalysts is the generation and utilization of benzenoid–quinoid donor–acceptor (D–A) couples inside the phenolic resin frameworks. However, there are often more donors than acceptors in phenolic resin due to the sluggish kinetics of in situ oxidation of phenols to quinoid methides, leading to a mismatched D/A ratio. Herein, we report a well-cross-linked phenolic resin with a unity D/A ratio synthesized by using phloroglucinol as a building block for condensation with formaldehyde. The higher electron density on the aromatic ring not only facilitates the in situ oxidation of phloroglucinols to quinoid methides, forming equivalent D–A couples, but also lowers the energy barrier for the condensation reaction, resulting in a highly cross-linked framework with a well-developed π-conjugated electronic structure. The phloroglucinol-formaldehyde resin product demonstrates significantly improved photocatalytic performance in the selective oxidation of methyl phenyl sulfide and the oxidative coupling of benzylamine. Our approach shows the potential of photocatalytic phenolic resins for solar-induced chemical conversion.

The mechanism of the quinoline transfer hydrogenation (TH) by aqueous HCOOH under the action of [Cp*Co(quinNH₂)I]⁺ (A*; quinNH₂ = 8-aminoquinoline) has been investigated by a combination of experiments and density functional theory (DFT) calculations. Variable-temperature (−40 to 20 °C) ¹H NMR in the absence of quinoline substrate shows rapid equilibration between A* and the formate complex [Cp*Co(quinNH₂)(O₂CH)]⁺ (B*) upon the addition of HCOOH/NEt₃ in MeOH, yielding ΔH° = 1.49 ± 0.03 kcal mol^–1 and ΔS° = 1.92 ± 0.06 cal mol^–1 K^–1. This equilibrium mixture slowly converts by decarboxylation and deprotonation to paramagnetic (S = 1) [Cp*Cp(quinNH₂)] (C*), indirectly identified by derivatization to [Cp*Co(CN^tBu)₂] and further I₂ oxidation to [Cp*Co(CN^tBu)₂I](I₃). The rate law of the [Cp*Co(quinNH₂)I]⁺-catalyzed 8-methylquinoline (8MQ) TH with HCOOH in D₂O at 80 °C has order one for substrate and catalyst and order zero for HCOOH, with a rate constant k = (1.52 ± 0.05) × 10^–2 s^–1 mol^–1 L. The quinoline (Q) TH with HCOOH in D₂O at 80 °C (k = (2.04 ± 0.05) × 10^–2 s^–1 mol^–1 L) selectively yields tetrahydroquinoline doubly D-labeled at the C³ position ([3,3-D₂]-THQ). Under the same conditions, DCOOD in D₂O yields [2,3,3,4-D₄]-THQ with k = (6.6 ± 0.6) × 10^–3 s^–1 mol^–1 L (KIE = k_H/k_D = 3.1 ± 0.5), while DCOOD in H₂O yields [2,4-D₂]-THQ. DFT calculations of the Cp model system point to a catalytic cycle with both diamagnetic and paramagnetic intermediates. A key aspect is that the transfer of the formate H atom as a hydride to the metal center, converting [CpCo(quinNH₂)(O₂CH)]⁺ (B) to [CpCo(quinNH₂)H]⁺ (D), is faster than its transfer as a proton to yield [CpCp(quinNH₂)] (C). This is at variance with the closely related complex with the 8-hydroxyquinoline ligand (ACS Catal. 2021, 11, 11906–11920), underlining the decisive roles of ligand and reaction medium in the selection of the dehydrogenation pathway.

Precise control and understanding of surface changes in indium (In)-based catalysts during the electrocatalytic CO₂ reduction reaction (CO₂RR) process are challenging. This study presents a series of surface-reconstructed In₂O₃–Bi electrocatalysts, created by doping mesoporous In₂O₃ nanocubes with bismuth (Bi). This doping introduces abundant bimetallic In–Bi sites at the crystal–amorphous interfaces, enhancing the CO₂-to-formate conversion selectivity. Bi atoms accelerate the surface reconstruction of In₂O₃, reduce the charge density around In atoms, and promote partial amorphization. In situ X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) measurements and density functional theory (DFT) calculations show that the bimetallic In–Bi sites lower the energy barrier for the HCOOH* intermediate, enhance H₂O dissociation, and inhibit the hydrogen evolution reaction (HER). The surface-reconstructed In_1.8Bi_0.2O₃ electrocatalyst demonstrates a Faradaic efficiency (FE) of 92.6% and a partial current density of −28.5 mA·cm^–2 and operates stably for 110 h in a H-type cell. In a flow cell, it achieves an FE of formate (FE_formate) of 97.6% at −1.4 V_RHE and maintains above 94% FE_formate over a potential window of 800 mV (from −1.0 to −1.8 V vs RHE). This study offers an effective approach for designing high-performance electrocatalysts for the CO₂RR based on surface reconstruction.

An isopentenol utilization pathway-based method for the investigation of the cyclization mechanism of terpene cyclases (TCs) is developed. By feeding deuterium-labeled prenols/isoprenols in combination with unlabeled ones to engineered E. coli hosts, terpene products with certain deuterium labeling patterns at hydrogen-bearing positions were obtained that can be used for deducing the cyclization processes, especially for those steps involving stereoselective hydride/proton shifts. Different types of TCs of varied origins for the biosynthesis of six known terpenes were used to test the scope and limitations of this method. Reliable results without significant deuterium dilution and scrambling are obtained by using this “deuterium-scanning” method and are consistent with those obtained previously. Limitations exist in the deuterium transfer process between those positions that are derived from the same labeled position of isoprenol, as exemplified by the failure of precisely tracking the origin of each deuterium in the labeled fusicocca-2,10(14)-diene obtained by feeding [2,2-²H₂]-isoprenol. Nonetheless, the newly developed method could be used as an alternate to those using custom-labeled oligoprenyl diphosphates for probing the cyclization mechanism of TCs.

The synthetic innovations in generating β-arylethylamines have the potential to propel advancements in drug discovery, as β-arylethylamines are common structural motifs in various bioactive compounds and drugs. Here, we report an efficient Pd (II)-catalyzed method for the selective β-C(sp³)-H arylation of aliphatic amines to construct β-arylethylamine frameworks. With the easy installation and removal of the nitroso directing group on the amine nitrogen, this Pd-catalyzed method enables (hetero)arylation of the β-C(sp³)-H bonds on various aliphatic amine scaffolds to produce β-arylethylamines and tolerates a variety of functional groups on both coupling partners. It offers an approach to direct syntheses of β-arylethylamine drugs from common native amines, thereby overcoming inherent limitations of previously known methods. This identified Pd-catalyst-system features low catalyst loading for C–H functionalization and offers a high reaction rate, originating from the pyridone-amide-ester ligand that increases the activity of the Pd catalyst while protecting all active species from forming inactive Pd complexes. Experimental and computational studies disclose that the valuable ligand effect partially results from the pendant ester group that participates in several steps of the C(sp³)-H activation process and favors the Pd-catalytic cycle.

In the modern era of organic synthesis, mechanisms centered on radical intermediates have become increasingly impactful. Among all of these, hydrogen atom transfer (HAT) represents one of the most fundamental chemical reaction steps and has found applications in designing practical transformations. Herein, we present a detailed case study on selective hydrodefluorination of trifluoromethylarenes utilizing N-heterocyclic carbene boranes (NHC-boranes) as the hydrogen atom donor. Under the optimal conditions featuring an acridine-based photocatalyst, complete selectivity for mono-hydrodefluorination was achieved across a wide array of substrates. Comprehensive mechanistic studies combining experimental and computational approaches disproved a chain process involving fluorine atom transfer but rather pointed to a HAT non-chain mechanism, where the key step involves the difluorobenzylic radical abstracting a hydrogen atom from the NHC-borane to generate a boryl radical in a polarity-matched fashion. Evaluation of a selection of Lewis base-ligated boranes revealed molecular descriptors critical to the outcomes of this reaction, and a classification model was built to explain the structure–reactivity relationship and how various elementary steps can be influenced. These results collectively provide valuable information for future reaction design to increase the utility of boranes in organic radical chemistry.

A synergistic photoredox and palladium-catalyzed 1,3-acyloxyallylation of aryl cyclopropanes with allyl esters has been developed. Aryl cyclopropanes are unprecedentedly employed as radical precursors in palladium-catalyzed allylation reactions with allyl esters acting as bifunctional reagents, thereby providing acyloxy groups as nucleophiles and the allyl moiety as a radical scavenger for the formation of benzylic C(sp³)–C(sp³) bonds. This redox-neutral reaction exhibits 100% atom economy and good functional group tolerance and has been successfully applied to the late-stage modification of pharmaceutical derivatives.

The catalytic cycloisomerization of nucleophile-functionalized alkynes is a useful method for the synthesis of heterocyclic compounds with 100% atom economy. Group 8 catalysts give high endo-selectivity in these transformations due to their ability to invoke metal-vinylidene intermediates. However, all known group 8 catalysts have relatively low activities and require high temperatures. Here, we report bifunctional ruthenium catalysts that enable the cycloisomerization of a large variety of substrates at low catalyst loadings and ambient temperature with turnover frequencies as high as 200 s^–1.

Electrochemical hydrogenation of furfural (EHF) to furfuryl alcohol (FA) presents a promising, yet challenging, avenue due to its inherently low performance and selectivity. In this study, we introduce a highly efficient and selective electrochemical system for FA production, employing a PtCu catalyst within a membrane-electrode assembly (MEA). Comprehensive investigations, including electrochemical kinetic analysis, material characterizations, and density functional theory (DFT) calculations, reveal that the incorporation of Cu onto Pt surfaces reduces the energy barrier for the proton-coupled electron transfer (PCET) reaction of adsorbed furfural and optimizes the adsorption energy for intermediates. These enhancements significantly increase the reaction rate and selectivity for FA production. The optimized PtCu catalyst exhibits high EHF performance in the MEA system, achieving a Faradaic efficiency exceeding 80% for FA at a current density of 30 mA cm^–2 with a cell voltage of 1.7 V.

Oxygen evolution reaction (OER) catalyst stability metrics derived from aqueous model systems (AMSs) prove valuable only if they are transferable to technical membrane electrode assembly (MEA) settings. Currently, there is consensus that stability data derived from ubiquitous rotating disk electrode (RDE)-based investigations substantially overestimate material degradation mainly due to the nonideal inertness of catalyst-backing electrode materials as well as bubble shielding of the catalyst by evolved oxygen. Despite the independently developed understanding of these two processes, their interplay and relative impact on intrinsic and operational material stability have not yet been established. Herein, we employ an inverted RDE-based approach coupled with online gas chromatographic quantification that exploits buoyancy and anode hydrophilicity existing under operating acidic OER conditions and excludes the influence of bubble retention on the surface of the catalyst. This approach thus allows us to dissect the degradation process occurring during the RDE-based OER stability studies. We demonstrate that the stability discrepancy between galvanostatic nanoparticle (NP)-based RDE and MEA data does not originate from the accumulation of bubbles in the catalyst layer during water oxidation but from the utilization of corrosion-prone substrate materials in the AMS. Moreover, we provide mechanistic insights into the degradation process and devise experimental measures to mitigate or circumvent RDE-related limitations when the technique is to be applied to an OER catalyst stability assessment. These findings should facilitate the transferability between AMS and MEA approaches and promote further development of the latter.

2,5-Furandicarboxylic acid (FDCA) is a promising biomass-derived alternative to fossil-based terephthalic acid. The catalytic oxidation of 5-hydroxymethylfurfural (HMF) to FDCA is widely recognized as a viable route for producing FDCA at industrially relevant concentrations (approximately 20 wt %); however, this has not yet been achieved. Toward this goal, we report that through controlled engineering of an oxygen-vacancy-enriched Mn/Co oxide as the support for Pt nanoparticles, a heterostructure of Pt/PtO₂ with electron-rich interfacial Pt–O–Mn sites (Pt/Mn₁₀Co₁O_x-VC) is formed, significantly enhancing the adsorption and activation of O₂, HMF, and its key intermediates. As a result, selective oxidation of both HMF (up to 40 wt %) and crude HMF (10 wt % and 70 wt % purity) was achieved with high FDCA yields ranging from 83% to 95% under base-free conditions, demonstrating strong economic feasibility and industrial potential for FDCA production. This work highlights the rational design of interfacial structures for the efficient oxidation of biomass-derived aldehydes and alcohols to bio-based dicarboxylic acids at industrially relevant concentrations, paving the way for FDCA to serve as a sustainable alternative to terephthalic acid as a comonomer in polyester production.

We report the synthesis and characterization of an artificial peroxygenase (CoN₄SA-POase) with CoN₄ active sites by supporting single-atom cobalt on polymeric carbon nitrogen, which exhibits high activity, selectivity, stability, and reusability in the oxidation of aromatic alkanes to ketones. Density functional theory calculations reveal a different catalytic mechanism for the artificial peroxygenase from that of natural peroxygenases. In addition, continuous-flow systems are employed to combine CoN₄SA-POase with enantiocomplementary ketoreductases as well as an amine dehydrogenase, enabling the enantioselective synthesis of chiral alcohols and amines from hydrocarbons with significantly improved productivity. This work, emulating nature and beyond nature, provides a promising design concept for heme enzyme-based transformations.

CO₂ to long-chain linear α-olefins (LAOs) is an effective strategy for the production of LAOs and the realization of CO₂ resource utilization. However, effective control of CO₂ activation and chain growth to improve catalytic activity and LAOs selectivity remains a great challenge. Herein, we report that K–FeMn catalyst prepared by precoordinated combustion method exhibits prominent catalytic performance in the CO₂ hydrogenation to LAOs, which achieved more than 67% for selectivity of LAOs in C₄₊ hydrocarbon and CO₂ conversion of 36.6% at 320 °C, 1.5 MPa, and 30 g_cat.·h·mol^–1. The structure performance of the K–FeMn catalyst is well correlated. The catalysts prepared by precoordinated combustion possessed strong interactions between Fe and Mn species, which effectively promoted the generation of Fe-carbides and inhibited the hydrogenation of the generated olefins, thereby improving the selectivity of LAOs. These findings will provide a theoretical basis and guidance for an in-depth understanding of CO₂ hydrogenation to LAOs and the development of efficient catalysts.

Chiral η⁶-benzene ruthenium(II) (BenRu^II)-catalyzed asymmetric C–H activations are challenging and rarely seen in the literature. Herein, the asymmetric C–H activation/cyclization of sulfoximines with sulfoxonium ylides catalyzed by the chiral BenRu^II catalyst derived from (S)-H₈–BINOL is described. It provides efficient access to various sulfur-chiral 1,2-benzothiazine 1-oxides in high yields with high enantioselectivities (up to 99% yield and 98% ee). Kinetic resolution of racemic sulfoximines was also feasible. The reaction mechanism was studied by the tool of H/D exchange and the kinetic isotope effect. The metallacycle revealing the origin of chiral induction was prepared, characterized, and proved effective for the model reaction. This work demonstrates the great potential of chiral BenRu^II catalysts for asymmetric C–H activation.