Photocatalytic CO₂ conversion into solar fuels has an alluring prospect. However, the rapid recombination of photogenerated electron–hole pairs for TiO₂-based photocatalyst hinders its wide application. To alleviate this bottleneck, a ternary hybrid TiO₂–MnO_x–Pt composite is excogitated. Taking advantage of the surface junction between {001} and {101} facets, MnO_x nanosheets and Pt nanoparticles are selectively deposited on each facet by a facile photodeposition method. This design accomplishes the formation of two heterojunctions: p–n junction between MnO_x and TiO₂ {001} facet and metal–semiconductor junction between Pt and TiO₂ {101} facet. Both of them, together with the surface heterojunction between {001} and {101} facets, are contributive to the spatial separation of the photogenerated electron–hole pairs. Thanks to their cooperative and synergistic effect, the as-prepared composite photocatalyst exhibits a promoted yield of CH₄ and CH₃OH, which is over threefold of pristine TiO₂ nanosheets films. The conjecture of the mechanism that selective formation of multijunction structure maximizes the separation and transfer efficiency of photogenerated charge carriers is proved by the photoelectrochemical analysis. This work not only successfully achieves an efficient multijunction photocatalyst by ingenious design but also provides insight into the mechanism of the performance enhancement.

Metal (oxy)hydroxides (MO_xH_y, M = Fe, Co, Ni, and mixtures thereof) are important materials in electrochemistry. In particular, MO_xH_y are the fastest known catalysts for the oxygen evolution reaction (OER) in alkaline media. While key descriptors such as overpotentials and activity have been thoroughly characterized, the nanostructure and its dynamics under electrochemical conditions are not yet fully understood. Here, we report on the structural evolution of Ni_1−δCo_δO_xH_y nanosheets with varying ratios of Ni to Co, in operando using atomic force microscopy during electrochemical cycling. We found that the addition of Co to NiO_xH_y nanosheets results in a higher porosity of the as-synthesized nanosheets, apparently reducing mechanical stress associated with redox cycling and hence enhancing stability under electrochemical conditions. As opposed to nanosheets composed of pure NiO_xH_y, which dramatically reorganize under electrochemical conditions to form nanoparticle assemblies, restructuring is not found for Ni_1−δCo_δO_xH_y with a high Co content. Ni_0.8Fe_0.2O_xH_y nanosheets show high roughness as-synthesized which increases during electrochemical cycling while the integrity of the nanosheet shape is maintained. These findings enhance the fundamental understanding of MO_xH_y materials and provide insight into how nanostructure and composition affect structural dynamics at the nanoscale.

Oxysulfoselenide semiconductor photocatalysts absorb light at longer wavelengths than the corresponding oxysulfides. However, the synthesis of oxysulfoselenides is challenging due to excessive particle growth and the limited availability of metal selenide precursors. In this study, a La₅Ti₂CuS₅O₇ (LTCSO) oxysulfide was annealed with Se powder in sealed, evacuated quartz tubes to obtain LTCSO:Se photocatalysts, and the properties of these materials were investigated. Se was found to be incorporated into the LTCSO upon heating at 973 K or higher, and the Se/(S + Se) ratio was increased to a maximum of 0.3 upon repeating the heat treatment twice. The addition of Se extended the absorption edge of the LTCSO and thus increased its photocatalytic H₂ evolution activity at longer wavelength. Even so, the apparent quantum yield at shorter wavelengths was reduced, which is similar to the results obtained for La₅Ti₂Cu(S_1–xSe_x)₅O₇ (LTCS_1–xSe_xO) solid solutions. Overall water splitting was achieved by constructing photocatalyst sheets using LTCSO:Se and LTCS_1–xSe_xO as hydrogen evolution photocatalysts and BiVO₄ as an oxygen evolution photocatalyst. Heat treatment with Se is evidently an effective method for the transformation of oxysulfide photocatalysts to oxysulfoselenides that promote photocatalytic H₂ evolution and have longer absorption edge wavelengths.

Silatrane surface anchors are protected siloxanes that are known to bond firmly (from pH 2–11) to metal oxide electrodes under heating. However, these conditions are not always compatible with the other functionality present. A silatrane-containing porphyrin molecule and a silatrane-containing ruthenium complex have now been designed, synthesized and optimized conditions have been identified for surface binding. Two mild, room-temperature surface binding methods were explored: binding with or without an acidic pretreatment; these methods were compared to the traditional, harsher binding conditions involving strong heating. We find that a preacidified electrode gave comparable surface loadings at room temperature compared to sensitization by using the previous strong heating method. This was also true on TiO₂, SnO₂, and nanoITO electrodes and thus may be generalizable. The new, milder binding methods also resulted in excellent aqueous and electrochemical stability from pH 2–11. Using a water-insoluble porphyrin with a silatrane anchor further increased the aqueous stability of the deposit, aided by the insolubility of the porphyrin. Finally, X-ray photoelectron spectroscopy (XPS) data confirmed for the first time that the triethanolamine released from the silatrane on deprotection/binding in turn binds to TiO₂, SnO₂, and nanoITO electrodes. This undesired triethanolamine deposit was easily removed from the surface by electrochemical voltage cycling or with an aqueous acidic wash for 1 h.

The design of photocatalysts able to reduce CO₂ to value-added chemicals and fuels could enable a closed carbon circular economy. A common theme running through the design of photocatalysts for CO₂ reduction is the utilization of semiconductor materials with high-energy conduction bands able to generate highly reducing electrons. Far less explored in this respect are low-energy conduction band materials such as WO₃. Specifically, we focus attention on the use of Pd nanocrystal decorated WO₃ nanowires as a heretofore-unexplored photocatalyst for the hydrogenation of CO₂. Powder X-ray diffraction, thermogravimetric analysis, ultraviolet–visible-near infrared, and in situ X-ray photoelectron spectroscopy analytical techniques elucidate the hydrogen tungsten bronze, H_yWO_3–x, as the catalytically active species formed via the H₂ spillover effect by Pd. The existence in H_yWO_3–x of Brønsted acid hydroxyls OH, W(V) sites, and oxygen vacancies (V_O) facilitate CO₂ capture and reduction reactions. Under solar irradiation, CO₂ reduction attains CO production rates as high as 3.0 mmol g_cat^–1 hr^–1 with a selectivity exceeding 99%. A combination of reaction kinetic studies and in situ diffuse reflectance infrared Fourier transform spectroscopy measurements provide a valuable insight into thermochemical compared to photochemical surface reaction pathways, considered responsible for the hydrogenation of CO₂ by Pd@H_yWO_3–x.

The performance of a photoelectrochemical (PEC) system is highly dependent on the charge separation, transport and transfer characteristics at the photoelectrode|electrolyte interface. Of the factors that influence the charge behaviors, the crystalline facets of the semiconductor in contact with the electrolyte play an important role but has been poorly studied previously. Here, we present a study aimed at understanding how the different facets of hematite affect the charge separation and transfer behaviors in a solar water oxidation reaction. Specifically, hematite crystallites with predominantly {012} and {001} facets exposed were synthesized. Density functional theory (DFT) calculations revealed that hematite {012} surfaces feature higher OH coverage, which was confirmed by X-ray photoelectron spectroscopy (XPS). These surface OH groups act as active sites to mediate water oxidation reactions, which plays a positive role for the PEC system. These surface OH groups also facilitate charge recombination, which compromises the charge separation capabilities of hematite. Indeed, intensity modulated photocurrent spectroscopy (IMPS) confirmed that hematite {012} surfaces exhibit higher rate constants for both charge transfer and recombination. Open circuit potential (OCP) measurements revealed that the hematite {012} surface exhibits a greater degree of Fermi level pinning effect. Our results shed light on how different surface crystal structures may change surface kinetics and energetics. The information is expected to contribute to efforts on optimizing PEC performance for practical solar fuel synthesis.

Constructing semiconductor heterojunctions via surface/interface engineering is an effective way to enhance the charge carrier separation/transport ability and thus the photoelectrochemical (PEC) properties of a photoelectrode. Herein, we report a conformal BiVO₄-layer/WO₃-nanoplate-array heterojunction photoanode modified with cobalt phosphate (Co-Pi) as oxygen evolution cocatalyst (OEC) for significant enhancement in PEC performances. The BiVO₄/WO₃ nanocomposite is fabricated by coating a thin conformal BiVO₄ layer on the surface of presynthesized WO₃ nanoplate arrays (NPAs) via stepwise spin-coating, and the decoration of Co-Pi OEC is realized by photoassisted electrodeposition method. The optimized Co-Pi@BiVO₄/WO₃ heterojunction photoanode shows a maximum photocurrent of 1.8 mA/cm² at 1.23 V vs RHE in a phosphate buffer electrolyte under an AM1.5G solar simulator, which is 5 and 12 times higher than those of bare WO₃ and BiVO₄ photoanode, respectively. Measurements of UV–vis absorption spectra, electrochemical impedance spectra (EIS) and photoluminescence (PL) spectra reveal that the enhanced PEC performances can be attributed to the increased charge carrier separation/transport benefited from the type II nature of BiVO₄/WO₃ heterojunction and the promoted water oxidation kinetics and photostability owing to the decoration of Co-Pi cocatalyst.

A Ru(II)–Re(I) supramolecular photocatalyst and a Ru(II) redox photosensitizer were both deposited successfully on a NiO electrode by using methyl phosphonic acid anchoring groups and the electrochemical polymerization of the ligand vinyl groups of the complexes. This new molecular photocathode, poly-RuRe/NiO, adsorbed a larger amount of the metal complexes compared to one using only methyl phosphonic acid anchor groups, and the stability of the complexes on the NiO electrode were much improved. The poly-RuRe/NiO acted as a photocathode for the photocatalytic reduction of CO₂ at E = −0.7 V vs Ag/AgCl under visible-light irradiation in an aqueous solution. The poly-RuRe/NiO produced approximately 2.5 times more CO, and its total Faradaic efficiency of the reduction products improved from 57 to 85%.

An oxyhalide photocatalyst Bi₄NbO₈Cl has recently been proven to stably oxidize water under visible light, enabling the Z-scheme water splitting when coupled with another photocatalyst for water reduction. We herein report the synthesis of Bi₄NbO₈Cl particles via a flux method, testing various molten salts to improve its crystallinity and hence photocatalytic activity. The eutectic mixture of CsCl/NaCl with a low melting point allowed the formation of single-phase Bi₄NbO₈Cl at as low as 650 °C. Thus, synthesized Bi₄NbO₈Cl particles exhibited a well-grown and plate-like shape while maintaining surface area considerably higher than those grown with others fluxes. They showed three times higher O₂ evolution rate under visible light than the samples prepared via a solid-state reaction. Time-resolved microwave conductivity measurements revealed greater signals (approximately 4.8 times) owing to the free electrons in the conduction band, indicating much improved efficiency of carrier generation and/or its mobility. The loading of RuO₂ or Pt cocatalyst on Bi₄NbO₈Cl further enhanced the activity for O₂ evolution because of efficient capturing of free electrons, facilitating the surface chemical reactions. In combination with a H₂-evolving photocatalyst Ru/SrTiO₃:Rh along with an Fe³⁺/Fe²⁺ redox mediator, the RuO₂/Bi₄NbO₈Cl is an excellent O₂-evolving photocatalyst, exhibiting highly effective water splitting into H₂ and O₂ via the Z-scheme.

Sub-5 nm ultra-fine iron phosphide (FeP) nano-dots-modified porous graphitic carbon nitride (g-C₃N₄) heterojunction nanostructures are successfully prepared through the gas-phase phosphorization of Fe₃O₄/g-C₃N₄ nanocomposites. The incorporation of zero-dimensional (0D) ultra-small FeP nanodots co-catalysts not only effectively facilitate charge separation but also serve as reaction active sites for hydrogen (H₂) evolution. Herein, the strongly coupled FeP/g-C₃N₄ hybrid systems are employed as precious-metal-free photocatalysts for H₂ production under visible-light irradiation. The optimized FeP/g-C₃N₄ sample displays a maximum H₂ evolution rate of 177.9 μmol h^–1 g^–1 with the apparent quantum yield of 1.57% at 420 nm. Furthermore, the mechanism of photocatalytic H₂ evolution using 0D/2D FeP/g-C₃N₄ heterojunction interfaces is systematically corroborated by steady-state photoluminescence (PL), time-resolved PL spectroscopy, and photoelectrochemical results. Additionally, an increased donor density in FeP/g-C₃N₄ is evidenced from the Mott–Schottky analysis in comparison with that of parent g-C₃N₄, signifying the enhancement of electrical conductivity and charge transport owing to the emerging role of FeP. The density functional theory calculations reveal that the FeP/g-C₃N₄ hybrids could act as a promising catalyst for the H₂ evolution reaction. Overall, this work not only paves a new path in the engineering of monodispersed FeP-decorated g-C₃N₄ 0D/2D robust nanoarchitectures but also elucidates potential insights for the utilization of noble-metal-free FeP nanodots as remarkable co-catalysts for superior photocatalytic H₂ evolution.

The ability to tune the electronic properties of nanomaterials has played a major role in the development of sustainable energy technologies. Metallic nanocatalysts are at the forefront of these advances. Their unique properties become even more interesting when we can control the distribution of the electronic states in the nanostructure. Here, we provide a comprehensive evaluation of the electronic surface states in ultrasmall metallic nanostructures by combining experimental and theoretical methods. The developed strategy allows the controlled synthesis of bimetallic nanostructures in the core–shell configuration, dispensing of the use of any surfactant or stabilizing agents, which usually inactivate important surface phenomena. The synthesized ultrasmall Au@Pt nanoarchitecture (∼1.8 nm) presents an enhanced performance catalyzing the hydrogen evolution reaction. First-principles calculations of projected and space-resolved local density of states of Au₅₅@Pt₉₂ (core–shell), Au₅₅Pt₉₂ (alloy), and Pt₁₄₇ nanoparticles show a prominent increase in the surface electronic states for the core–shell bimetallic nanomaterial. It arises from a more-effective charge transfer from gold to the surface platinum atoms in the core–shell configuration. In pure Pt₁₄₇ or Au₅₅Pt₉₂ alloy nanoparticles, a great part of the electronic states near the Fermi level is buried in the core atoms, disabling these states for catalytic applications. The proposed experimental–theoretical approach may be useful for the design of other systems composed of metallic nanoparticles supported on distinct substrates, such as two-dimensional materials and porous matrices. These nanomaterials find several applications not only in heterogeneous catalysis but also in sensing and optoelectronic devices.

Reliable integration of thin film solid-state polymer electrolytes (SPEs) with 3D electrodes is one major challenge in microbattery fabrication. We used initiated chemical vapor deposition (iCVD) to produce a series of nanoscale copolymer films comprising hydroxyethyl methacrylate and ethylene glycol diacrylate. Conformal copolymer coatings were applied to a variety of patterned 3D electrodes and subsequently converted into ionic conductors by lithium salt doping. Broad tunability in ionic conductivity was achieved by optimizing the copolymer cross-linking density and matrix polarity, resulting in a room-temperature conductivity of (6.1 ± 2.7) × 10^–6 S cm^–1, the highest value reported for conformal, nanoscale SPEs.

Solution-processed two-dimensional materials offer a scalable route toward next-generation printed devices. In this report, we demonstrate fully inkjet-printed photodetectors using molybdenum disulfide (MoS₂) nanosheets as the active material and graphene as the electrodes. Percolating films of semiconducting MoS₂ with high electrical conductivity are achieved with an ethyl cellulose-based ink formulation. Two classes of photodetectors are fabricated, including thermally annealed devices on glass with fast photoresponse of 150 μs and photonically annealed devices on flexible polyimide with high photoresponsivity exceeding 50 mA/W. The photonically annealed photodetector also reduces the curing time to milliseconds and maintains functionality over 500 bending cycles.

The development of commercially friendly and stable catalysts for oxygen reduction reaction (ORR) is critical for many energy conversion systems such as fuel cells and metal–air batteries. Many Co-based perovskite oxides such as LaCoO₃ have been discovered as the stable and active ORR catalysts, which can be good candidates to replace platinum (Pt). Although researchers have tried substituting various transition metals into the Co-based perovskite catalysts to improve the ORR performance, the influence of substitution on the ORR mechanism is rarely studied. In this paper, we explore the evolution of ORR mechanism after substituting Fe into LaCoO₃, using the combination of X-ray photoelectron spectroscopy, high-resolution X-ray microscopy, X-ray diffraction, surface-sensitive soft X-ray absorption spectroscopy characterization, and electrochemical tests. We observed enhanced catalytic activities and increased electron transfer numbers during the ORR in Co-rich perovskite, which are attributed to the optimized e_g filling numbers and the stronger hybridization of transition metal 3d and oxygen 2p bands. The discoveries in this paper provide deep insights into the ORR catalysis mechanism on metal oxides and new guidelines for the design of Pt-free ORR catalysts.

Lithium–sulfur (Li–S) batteries have now emerged as the next-generation rechargeable energy storage system because of the high energy density and theoretical capacity. However, the notorious “lithium polysulfide (LiPS) shuttle” and sluggish kinetics in sulfur redox have posted great threat to their practical applications. Herein, we develop a VN-modified separator as an effective promoter to regulate the LiPSs and accelerate the electrochemical kinetics of Li–S batteries. Benefiting from the dense packing structure and polar surface of porous VN, the VN-modified separator favorably synergizes bifunctionality of physical confinement and chemical entrapment toward LiPSs while affording smooth lithium-ion migration. In addition, the superb electrical conductivity of VN also propels the LiPS conversion. With these advantages, thus-integrated batteries with VN-modified separator exhibit an average capacity decay of 0.077% per cycle at 1 C for 800 cycles. A reasonable areal capacity of 4.2 mAh cm^–2 is achieved even with a high sulfur mass loading of 3.8 mg cm^–2 at 0.2 C. The present work offers a rational strategy to regulate the LiPS behavior and guide the sulfur redox kinetics toward effective and long-life Li–S batteries.

Cucurbit[7]uril (CB[7]) macrocycles exhibit a broad range of host–guest binding affinity. Attaching pendant CB[7] and complementary guests on 8-arm PEG macromers affords supramolecular hydrogels with cross-link affinity spanning more than 5 orders of magnitude (1.5 × 10⁷ to 5.4 × 10¹² M^–1) without changing network topology. Cross-link affinity translates directly to bulk dynamic properties; hydrogels with high-affinity cross-linking behave like covalent gels with limited ability to relax or self-heal. Cross-link affinity furthermore dictates the release rate of encapsulated macromolecules, as well as cell infiltration and material clearance in vivo. This work thus informs a role for affinity in dictating supramolecular hydrogel properties by quantifying and isolating this feature over an unprecedented range.

The development of an intelligent biomaterial system that can efficiently accumulate at the tumor site and release a drug in a controlled way is very important for cancer chemotherapy. PEG is widely selected as a hydrophilic shell to acquire prolonged circulation time and enhanced accumulation at the tumor site, but it also restrains the cellular transport and uptake and leads to insufficient therapeutic efficacy. In this work, a PEG-detachable pH-responsive polymer that forms micelles from copolymer cholesterol grafted poly(ethylene glycol) methyl ether-D_labile-poly(β-amino ester)-D_labile-poly(ethylene glycol) methyl ether (MPEG-D_labile-PAE-g-Chol) is developed to overcome the aforementioned challenges based on pH value changes among normal physiological, extracellular (pH_e), and intracellular (pH_i) environments. PEGylated doxorubicin (DOX)-loaded polymeric micelles (DOX-PMs) can accumulate at the tumor site via an enhanced permeability and retention effect, and the PEG shell is detachable induced by cleavage of the pH_e-labile linker between the PEG segment and the main chain. Meanwhile, the pH_i-sensitive poly(β-amino ester) segment is protonated and has a high positive charge. The detachment of PEG and protonation of PAE facilitate cellular uptake of DOX-PMs by negatively charged tumor cells, along with the escape from endo-/lysosome due to the “proton-sponge” effect. The DOX molecules are controlled release from the carriers at specific pH values. The results demonstrate that DOX-PMs have the capability of showing high therapeutic efficacy and negligible cytotoxicity compared with free DOX in vitro and in vivo. Overall, we anticipate that this PEG-detachable and tumor-acidity-responsive polymeric micelle can mediate effective and biocompatible drug delivery “on demand” with clinical application potential.

Biomedical applications of three-dimensional (3D) printing demand complex hydrogel-based constructs laden with living cells. Advanced support materials facilitate the fabrication of such constructs. This work demonstrates the versatility and utility of a gellan fluid gel as a support bath material for fabricating freeform 3D hydrogel constructs from a variety of materials. Notably, the gellan fluid gel support bath can supply sensitive biological cross-linking agents such as enzymes to printed fluid hydrogel precursors for mild covalent hydrogel cross-linking. This mild fabrication approach is suitable for fabricating cell-laden gelatin-based constructs in which mammalian cells can form intercellular contacts within hours of fabrication; cellular activity is observed over several days within printed constructs. In addition, gellan is compatible with a wide range of ionic and thermal conditions, which makes it a suitable support material for ionically cross-linked structures generated by printing alginate-based ink formulations as well as thermosensitive hydrogel constructs formed from gelatin. Ultraviolet irradiation of printed structures within the support bath is also demonstrated for photoinitiated cross-linking of acrylated ink materials. Furthermore, gellan support material performance in terms of printed filament stability and residual support material on constructs is found to be comparable and superior, respectively, to previously reported support materials.

The use of magnetic nanoparticles in oncothermia has been investigated for decades, but an effective combination of magnetic nanoparticles and localized chemotherapy under clinical magnetic hyperthermia (MH) conditions calls for novel platforms. In this study, we have engineered magnetic thermoresponsive iron oxide nanocubes (TR-cubes) to merge MH treatment with heat-mediated drug delivery, having in mind the clinical translation of the nanoplatform. We have chosen iron oxide based nanoparticles with a cubic shape because of their outstanding heat performance under MH clinical conditions, which makes them benchmark agents for MH. Accomplishing a surface-initiated polymerization of strongly interactive nanoparticles such as our iron oxide nanocubes, however, remains the main challenge to overcome. Here, we demonstrate that it is possible to accelerate the growth of a polymer shell on each nanocube by simple irradiation of a copper-mediated polymerization with a ultraviolet light (UV) light, which both speeds up the polymerization and prevents nanocube aggregation. Moreover, we demonstrate herein that these TR-cubes can carry chemotherapeutic doxorubicin (DOXO-loaded-TR-cubes) without compromising their thermoresponsiveness both in vitro and in vivo. In vivo efficacy studies showed complete tumor suppression and the highest survival rate for animals that had been treated with DOXO-loaded-TR-cubes, only when they were exposed to MH. The biodistribution of intravenously injected TR-cubes showed signs of renal clearance within 1 week and complete clearance after 5 months. This biomedical platform works under clinical MH conditions and at a low iron dosage, which will enable the translation of dual MH/heat-mediated chemotherapy, thus overcoming the clinical limitation of MH: i.e., being able to monitor tumor progression post-MH-treatment by magnetic resonance imaging (MRI).

Despite major technological advances within the field of cardiovascular engineering, the risk of thromboembolic events on artificial surfaces in contact with blood remains a major challenge and limits the functionality of ventricular assist devices (VADs) during mid- or long-term therapy. Here, a biomimetic blood–material interface is created via a nanofiber-based approach that promotes the endothelialization capability of elastic silicone surfaces for next-generation VADs under elevated hemodynamic loads. A blend fiber membrane made of elastic polyurethane and low-thrombogenic poly(vinylidene fluoride-co-hexafluoropropylene) was partially embedded into the surface of silicone films. These blend membranes resist fundamental irreversible deformation of the internal structure and are stably attached to the surface, while also exhibiting enhanced antithrombotic properties when compared to bare silicone. The composite material supports the formation of a stable monolayer of endothelial cells within a pulsatile flow bioreactor, resembling the physiological in vivo situation in a VAD. The nanofiber surface modification concept thus presents a promising approach for the future design of advanced elastic composite materials that are particularly interesting for applications in contact with blood.

Mixed micelles based on amphiphilic gadolinium(III)-DOTA and europium(III)-DTPA complexes were synthesized and evaluated for their paramagnetic and optical properties as potential bimodal contrast agents. Amphiphilic folate molecule for targeting the folate receptor protein, which is commonly expressed on the surface of many human cancer cells, was used in the self-assembly process in order to create nanoaggregates with targeting properties. Both targeted and nontargeted nanoaggregates formed monodisperse micelles having distribution maxima of 10 nm. The micelles show characteristic europium(III) emission with quantum yields of 2% and 1.1% for the nontargeted and targeted micelles, respectively. Fluorescence microscopy using excitation at 405 nm and emission at 575–675 nm was employed to visualize the nanoaggregates in cultured HeLa cells. The uptake of folate-targeted and nontargeted micelles is already visible after 5 h of incubation and was characterized with the europium(III) emission, which is clearly observable in the cytoplasm of the cells. The very fast longitudinal relaxivity r₁ of ca. 26 s^–1 mM^–1 per gadolinium(III) ion was observed for both micelles at 60 MHz and 310 K. Upon increasing the magnetic field to 300 MHz, the nanoaggregates exhibited a large switching to transversal relaxivity with r₂ value of ca. 52 s^–1 mM^–1 at 310 K. Theoretical fitting of the ¹H NMRD profiles indicate that the efficient T₁ and T₂ relaxations are sustained by the favorable magnetic and electron-configuration properties of the gadolinium(III) ion, rotational correlation time, and coordinated water molecule. These nanoaggregates could have versatile application as a positive contrast agent at the currently used magnetic imaging field strengths and a negative contrast agent in higher field applications, while at the same time offering the possibility for the loading of hydrophobic therapeutics or targeting molecules.

The fluorescence method has made great progress in the construction of sensitive sensors but the background fluorescence of the matrix and photobleaching limit its broad application in clinical diagnosis. Here, we propose a digital single virus immunoassay for multiplex virus detection by using fluorescent magnetic multifunctional nanospheres as both capture carriers and signal labels. The superparamagnetism and strong magnetic response ability of nanospheres can realize efficient capture and separation of targets without sample pretreatment. Due to their distinguishable fluorescence imaging and photostability, the nanospheres enable single-particle counting for ultrasensitive multiplexed detection. Furthermore, the integration of digital analysis provided a reliable quantitative strategy for the detection of rare targets. Based on multifunctional nanospheres and digital analysis, a digital single virus immunoassay was proposed for simultaneous detection of H9N2, H1N1, and H7N9 avian influenza virus without complex signal amplification, whose detection limits were 0.02 pg/mL. Owing to its good specificity and anti-interference ability, the method showed great potential in single biomolecules, multiplexed detection, and early diagnosis of diseases.

Recently, we developed ultrasmall molybdenum disulfide (MoS₂) quantum dots for computed tomography (CT) and multispectral optoacoustic tomography (MSOT) imaging-guided photothermal therapy (PTT). But, due to rapid body elimination and limited blood circulation time, the tumor uptake of the dots is low. In our study, this problem was solved via designing an amino-modified biodegradable nanomaterial based on MoS₂ quantum-dots-doped disulfide-based SiO₂ nanoparticles (denoted MoS₂@ss-SiO₂) for multimodal application. By integrating the MoS₂ quantum dots into clearable SiO₂ nanoparticles, this nanoplatform with an appropriate particle size can not only degrade and excrete in a reasonable period induced by redox responsiveness of glutathione but also exhibit a high tumor uptake due to the longer blood circulation time. Moreover, hyaluronic acid and chlorin e6 (Ce6) were adsorbed on the outer shell for tumor-targeting effect and photodynamic therapy, respectively. So, this biodegradable and clearable theranostic nanocomposite, which is applicable in integrated fluorescence/CT/MSOT imaging-guided combined photothermal therapy (PTT) and photodynamic therapy, is very promising in biomedical applications in the future.

The therapeutic properties of light are well known for photodynamic or photothermal therapy, which could cause irreversible photodamage to tumor tissues. Although photodynamic therapy (PDT) has been proved in the clinic, the efficacy is not satisfactory because of complicated tumor microenvironments. For example, the hypoxia in solid tumor has a negative effect on the generation of singlet oxygen. To address the hypoxia issues in PDT, leveraging alkyl radical is an available option due to the oxygen-independent feature. In this work, a new kind of organic nanoparticles (tripolyphosphate (TPP)-NN NPs) from porphyrin and radical initiator is developed. Under near-infrared light irradiation, TPP-NN NPs will split and release alkyl radical, which could induce obvious cytotoxicity both in normal and hypoxia environment. The photothermal-controlled generation of alkyl radical could significantly inhibit the growth of cervical cancer and show ignorable systemic toxicity. This activatable radical therapy opens up new possibilities for the application of PDT in hypoxia condition.

Photomediated cancer therapy, mainly including photothermal (PT) therapy (PTT) and photodynamic therapy (PDT), has attracted tremendous attention in recent years thanks to its noninvasive and stimuli-responsive features. The single mode of PTT or PDT, however, has obvious drawbacks, either requiring high-power laser irradiation to generate enough heat or only providing limited efficacy due to the hypoxia nature inside tumors. In addition, the reported synergistic PTT/PDT generally utilized two excitation sources to separately activate PTT and PDT, and the problem of high-power laser irradiation for PTT was still not well solved. Herein, a new concept, loading a small amount of photosensitizers onto a PTT agent (both of them can be triggered by a single-near-infrared (NIR) laser), was proposed to evade the shortcomings of PTT and PDT. To validate this idea, minute quantities of photosensitizer chlorin e6 (Ce6) (0.56% of mass) were anchored onto amino-rich red emissive carbon dots (RCDs) that possess superior photothermal (PT) character under 671 nm NIR laser (PT conversion efficiency to be 46%), and meanwhile the PDT of Ce6 can be activated by this laser irradiation as well. The findings demonstrate that Ce6-modified RCDs (named Ce6-RCDs) offer much higher cancer therapy efficacy under a reduced laser power density (i.e., 0.50 W cm^–2 at 671 nm) in vitro and in vivo than the equivalent RCDs or Ce6 under the same irradiation conditions. Besides, the Ce6-RCDs also exhibit multimodal imaging capabilities (i.e., fluorescence (FL), photoacoustic (PA), and PT), which can be employed for guidance of the phototherapy process. This study suggests not only a strategy to enhance cancer phototherapy efficacy but also a promising candidate (i.e., Ce6-RCDs) for multimodal FL/PA/PT imaging-guided and single-NIR-laser-triggered synergistic PTT/PDT for cancers by a reduced irradiation power.

Metal–peptide interactions provide plentiful resource and design principles for developing functional biomaterials and smart sensors. Pb²⁺, as a borderline metal ion, has versatile coordination modes. The interference from competing metal ions and endogenous chelating species greatly challenges Pb²⁺ analysis, especially in complicated living biosystems. Herein, a biomimetic peptide-based fluorescent sensor GSSH-2TPE was developed, starting from the structure of a naturally occurring peptide glutathione. Lewis acid–base theory was employed to guide the molecular design and tune the affinity and selectivity of the targeting performance. The integration of peptide recognition and aggregation-induced emission effect provides desirable sensing features, including specific turn-on response to Pb²⁺ over 18 different metal ions, rapid binding, and signal output, as well as high sensitivity with a detection limit of 1.5 nM. Mechanism investigation demonstrated the balance between the chelating groups, and the molecular configuration of the sensor contributes to the high selectivity toward Pb²⁺ complexation. The ion-induced supramolecular assembly lights up the bright fluorescence. The ability to image Pb²⁺ in living cells was exhibited with minimal interference from endogenous biothiols, no background fluorescence, and good biocompatibility. With good cell permeability, GSSH-2TPE can monitor changes in Pb²⁺ levels and biodistribution and thus predict possible damage pathways. Such metal–peptide interaction-based sensing systems offer tailorable platforms for designing bioanalytical tools and show great potential for studying the cell biology of metal ions in living biosystems.

Bioactive glasses are well-known materials suitable for bone-related applications thanks to their biocompatibility and osteoconductivity. In order to improve their in vivo performance, the modification of the glass composition by adding ions with specific biological functions is required. As copper (Cu) possesses antibacterial properties, in this study, 5 wt % of CuO has been added to the 45S5 bioactive glass composition. The investigation of the effect of the Cu-containing bioactive glass on cellular behavior has revealed that the presence of Cu induces an early differentiation of human mesenchymal stem cells through osteoblast phenotype, promotes the expression of anti-inflammatory interleukin, and reduces proinflammatory interleukin expression. With the aim to produce coatings with antibacterial properties, the Cu-containing bioactive glass was used as the target material for the pulsed laser deposition (PLD) of bioactive thin films. PLD experiments were carried out at different substrate temperatures to study the effect on the film’s characteristics. All of the films are compact, crack-free, and characterized by a rough morphology and good wettability. The in vitro bioactivity was demonstrated by the apatite growth on the coating surface, after soaking in simulated body fluid, revealed by Raman spectroscopy and scanning electron microscopy—energy dispersive X-ray analyses. The antibacterial study proved that the material showed more effective activity against three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica) rather than against Gram-positive bacteria (Staphylococcus aureus).

In this study, we established a long-term three-dimensional (3D) culture system by using integrin ligand modified alginate hydrogels to encapsulate and differentiate neural progenitor cells (NPCs) toward oligodendrocyte (OL) lineage cells. The porosity of the hydrogel was optimized by varying the alginate concentrations and then characterized by scanning electronic microscopy (SEM). The surface plasmon resonance (SPR) test was used to confirm the ligand-integrin interactions indicating adherence between the NPC surfaces and the hydrogels. Following encapsulation in the hydrogels, both mouse and human NPC sphere cultures could be maintained up to 90 days. Mouse NPC spheres were differentiated into viable neurons, astrocytes and mature OLs by day 60 in all groups whereas human NPC spheres were differentiated into neurons and later into GFAP positive astrocytes and O4 positive pre-OL within 90 days. The species difference in the timeline of OL development between mouse and human was reflected in this system. The ligand LXY30 interacting with the α3β1 integrin receptor was more effective in promoting the differentiation of hNPCs to OL lineage cells compared with the ligand LXW64 interacting with the αvβ3 integrin receptor, hyaluronic acid interacting with CD44 receptor or without any ligand. This study is the first to differentiate O4⁺ pre-OLs from hNPCs in a LXY30-α3β1 (integrin-ligand) modified alginate 3D hydrogel culture. This 3D platform could serve as a valuable tool in disease modeling, drug discovery, and NPC transplantation.

The potential of electrospun polydioxanone (PDX) mats as scaffolds for skeletal tissue regeneration was significantly enhanced through improvement of the cell-mediated biomimetic mineralization and multicellular response. This was achieved by blending PDX (i) with poly(hydroxybutyrate-co-valerate) (PHBV) in the presence of hydroxyapatite (HA) and (ii) with aloe vera (AV) extract containing a mixture of acemannan/glucomannan. In an exhaustive study, the behavior of the most relevant cell lines involved in the skeletal tissue healing cascade, i.e. fibroblasts, macrophages, endothelial cells and preosteoblasts, on the scaffolds was investigated. The scaffolds were shown to be nontoxic, to exhibit insignificant inflammatory responses in macrophages, and to be degradable by macrophage-secreted enzymes. As a result of different phase separation in PDX/PHBV/HA and PDX/AV blend mats, cells interacted differentially. Presumably due to varying tension states of cell–matrix interactions, thinner microtubules and significantly more cell adhesion sites and filopodia were formed on PDX/AV compared to PDX/PHBV/HA. While PDX/PHBV/HA supported micrometer-sized spherical particles, nanosized rod-like HA was observed to nucleate and grow on PDX/AV fibers, allowing the mineralized PDX/AV scaffold to retain its porosity over a longer time for cellular infiltration. Finally, PDX/AV exhibited better in vivo biocompatibility compared to PDX/PHBV/HA, as indicated by the reduced fibrous capsule thickness and enhanced blood vessel formation. Overall, PDX/AV blend mats showed a significantly enhanced potential for skeletal tissue regeneration compared to the already promising PDX/PHBV/HA blends.

Programmable drug delivery systems hold great promise to enhance cancer treatment. Herein, a programmable drug delivery system using a chondroitin sulfate (CS)-based composite nanoparticle was developed for enhancing and sensitizing chemotherapy to drug-resistant cancer. The nanoparticle was composed of a cross-linked CS hydrogel shell and hydrophobic cores containing both free drugs and CS-linked prodrugs. Interestingly, the nanoparticle could mediate tumor-specific CD44 targeting. After specific cellular uptake, the payloads were suddenly released because of the decomposition of the CS shell, and the free drug molecules with synergistic effects induced tumor-specific cytotoxicity rapidly. Subsequently, the inner cores of the nanoparticles sustainedly release their cargos in drug-resistant tumor cells to keep the effective drug concentration against the drug efflux mediated by P-glycoprotein. CS dissociated from the outer shell and sensitized cancer cells to the antitumor drugs through downregulation of Bcl-XL, an antiapoptosis protein. Such a programmable drug delivery system with specific tumor-targeting and sensitized therapy is promising for rational drug delivery and provides more versatility for controlled release in biomedical applications.

Melanoma is malignant skin cancer occurring with increasing prevalence with no effective treatment. A unique feature of melanoma cells is that they require higher concentrations of ltyrosine (l-tyr) for expansion than normal cells. As such, it has been demonstrated that dietary l-tyr restriction lowers systemic l-tyr and suppresses melanoma advancement in mice. Unfortunately, this diet is not well tolerated by humans. An alternative approach to impede melanoma progression will be to administer the enzyme tyrosinase (TYR), which converts l-tyr into melanin. Herein, a multicompartment carrier consisting of a polymer shell entrapping thousands of liposomes is employed to act as a microreactor depleting l-tyr in the presence of melanoma cells. It is shown that the TYR enzyme can be incorporated within the liposomal subunits with preserved catalytic activity. Aiming to mimic the dynamic environment at the tumor site, l-tyr conversion is conducted by co-culturing melanoma cells and microreactors in a microfluidic setup with applied intratumor shear stress. It is demonstrated that the microreactors are concurrently depleting l-tyr, which translates into inhibited melanoma cell growth. Thus, the first microreactor where the depletion of a substrate translates into antitumor properties in vitro is reported.

In artificial biological circulation systems such as extracorporeal membrane oxygenation, surface wettability is a critical factor in blood clotting problems. Therefore, to prevent blood from clotting, omniphobic surfaces are required to repel both hydrophilic and oleophilic liquids and reduce surface friction. However, most omniphobic surfaces have been fabricated by combining chemical reagent coating and physical structures and/or using rigid materials such as silicon and metal. It is almost impossible for chemicals to be used in the omniphobic surface for biomedical devices due to durability and toxicity. Moreover, a flexible and stable omniphobic surface is difficult to be fabricated by using conventional rigid materials. This study demonstrates a flexible and stable omniphobic surface by mimicking the re-entrant structure of springtail’s skin. Our surface consists of a thin nanohole membrane on supporting microstructures. This structure traps air under the membrane, which can repel the liquid on the surface like a spring and increase the contact angle regardless of liquid type. By theoretical wetting model and simulation, we confirm that the omniphobic property is derived from air trapped in the structure. Also, our surface well maintains the omniphobicity under a highly pressurized condition. As a proof of our concept and one of the real-life applications, blood experiments are performed with our flat and curved surfaces and the results including contact angle, advancing/receding angles, and residuals show significant omniphobicity. We hope that our omniphobic surface has a significant impact on blood-contacting biomedical applications.

Although self-healing gels with structural resemblance to biological tissues attract great attention in biomedical fields, it remains a dilemma for combination between fast self-healing properties and high mechanical toughness. On the basis of the design of dynamic reversible cross-links, we incorporate rigid tannic acid-coated cellulose nanocrystal (TA@CNC) motifs into the poly(vinyl alcohol) (PVA)–borax dynamic networks for the fabrication of a high toughness and rapidly self-healing nanocomposite (NC) hydrogel, together with dynamically adhesive and strain-stiffening properties that are particularly indispensable for practical applications in soft tissue substitutes. The results demonstrate that the obtained NC gels present a highly interconnected network, where flexible PVA chains wrap onto the rigid TA@CNC motifs and form the dynamic TA@CNC–PVA clusters associated by hydrogen bonds, affording the critical mechanical toughness. The synergetic interactions between borate–diol bonds and hydrogen bonds impart a typical self-healing behavior into the NC gels, allowing the dynamic cross-linked networks to undergo fast rearrangement in the time scale of seconds. Moreover, the obtained NC hydrogels not only mimic the main feature of biological tissues with the unique strain-stiffening behavior but also display unique dynamic adhesiveness to nonporous and porous substrates. It is expected that this versatile approach opens up a new prospect for the rational design of multifunctional cellulosic hydrogels with remarkable performance to expand their applications.

As one of the novel two-dimensional nanomaterials, black phosphorus nanosheets (BP NS) have been proven to be excellent carrier materials for drugs, owing to their fine optical properties and biocompatibility. In this work, a composite drug nanocarrier based on BP NS is proposed, which can perform a synergetic and targeted chemophotothermal therapy of acute lymphoblastic leukemia (ALL). First, BP NS were prepared by an improved liquid exfoliation technique. Then, polyethylene glycol (PEG) was modified on the surfaces of BP NS through electrostatic adsorption. Drug molecules can also be loaded onto the BP NS via electrostatic adsorption. The PEG layer can effectively protect the interior BP NS from water and air to enhance their physiological stability. The obtained PEGylated BP NS (BP NS@PEG) not only demonstrated an excellent photothermal conversion efficiency and photothermal stability but also exhibited a good pH and photothermal dual-responsive drug release behavior. In addition, the BP NS@PEG were further modified with Sgc8 aptamers through covalent bonding. The aptamers provided an efficient specificity toward ALL cells (CCRF-CEM) and greatly increased the endocytosis of the nanocarriers through a receptor-mediated manner, which can further improve the therapeutic effect. Hence, the presented BP NS-based multifunctional nanocarrier can achieve a targeted and synergetic chemophotothermal therapy of ALL, which shows a promising potential in improving the curative efficiency.

CO₂ photoconversion into hydrocarbon solar fuels by engineered semiconductors is considered as a feasible plan to address global energy requirements in times of global warming. In this regard, three-dimensional yolk@shell hydrogenated TiO₂/Co–Al layered double hydroxide (3D Y@S TiO_2–x/LDH) architecture was successfully assembled by sequential solvothermal, hydrogen treatment, and hydrothermal preparation steps. This architecture revealed a high efficiency for the photoreduction of CO₂ to solar fuels, without a noble metal cocatalyst. The time-dependent experiment indicated that the production of CH₃OH was almost selective until 2 h (up to 251 μmol/g_cat. h), whereas CH₄ was produced gradually by increasing the time of reaction to 12 h (up to 63 μmol/g_cat. h). This significant efficiency can be ascribed to the engineering of 3D Y@S TiO_2–x/LDH architecture with considerable CO₂ sorption ability in mesoporous yolk@shell structure and LDH interlayer spaces. Also, oxygen vacancies in TiO_2–x could provide excess sites for sorption, activation, and conversion of CO₂. Furthermore, the generated Ti³⁺ ions in the Y@S TiO₂ structure as well as connecting of structure with LDH plates can facilitate the charge separation and decrease the band gap of nanoarchitecture to the visible region.

The conversion reaction-based lithium–sulfur battery features an attractive energy density of 2600 W h/kg. Nevertheless, the unsatisfied performance in terms of poor discharge capacity and cycling stability still hinders its practical applications. Recently, porous carbon materials have been widely reported as promising sulfur reservoirs to promote the sluggish reaction kinetics of sulfur conversion, tolerate volume expansion of sulfur, and suppress polysulfide shuttling. However, porous carbon with a simply designed nanostructure is hard to satisfy all of these aspects simultaneously. Herein, we have applied a dual-template strategy that assembles carbon pores into carbon sheets to prepare three-dimensional (3D) nitrogen-doped porous carbon nanosheets (N-PCSs) as the multifunctional sulfur host for the Li–S battery. By arranging carbon pores within an interconnected 3D architecture, the porous carbon sheets enable rapid electron/ion transfer. Moreover, the micro/mesopores and nitrogen dopant in N-PCS provide both physical and chemical restrictions to polysulfide species. With these advances, the N-PCS/S cathode delivers a large initial discharge capacity of 1360 mA h/g at 0.1 C. When performed at 0.5 C for 1000 cycles, the cathode can still remain ∼50% of its capacity with a low decay rate of 0.05% per cycle, showing the important role of the 3D carbon material in the Li–S battery.

Nanocellulose has been used as a sustainable nanomaterial for constructing advanced electrochemical energy-storage systems with renewability, lightweight, flexibility, high performance, and satisfying safety. Here, we demonstrate a high-performance all-nanofiber asymmetric supercapacitor (ASC) assembled using a forest-based, nanocellulose-derived hierarchical porous carbon (nanocellulose carbon, HPC) anode, a mesoporous nanocellulose membrane separator (nanocellulose separator), and a NiCo₂O₄ cathode with nanocellulose carbon as the support matrix (nanocellulose cathode, HPC/NiCo₂O₄). HPC has a three-dimensional porous structure comprising interconnected nanofibers with an ultrahigh surface area of 2046 m² g^–1. When integrated with the mesoporous feature of the nanocellulose membrane separator, these properties facilitate the quick delivery of both ions and electrons even with a thick (up to several hundreds of micrometers) and highly loaded (5.8 mg cm^–2) ASC design. Consequently, the all-nanofiber ASC demonstrates a high electrochemical performance (64.83 F g^–1 (10.84 F cm^–3) at 0.25 A g^–1 and 32.78 F g^–1 or 5.48 F cm^–3 at 4 A g^–1) that surpasses most cellulose-based ASCs ever reported. Moreover, the nanocellulose components promise renewability, low cost, and biodegradability, thereby presenting a promising direction toward high-power, environmentally friendly, and renewable energy-storage devices.

Al-contained Li_7–xLa₃Zr_2–xTa_xO₁₂ (xTa-LLZO) powder was synthesized via solid-state reaction, where increasing the Ta doping level was found to reduce the average particle size and facilitate a higher relative density in the sintered pellet. 0.8Ta-LLZO pellets sintered at 1150 °C achieved a relative density of 96.2 ± 0.2% and survived the Li striping/plating test under a unidirectional current polarization of 0.5 mA/cm² for more than 8 h without short-circuiting. In contrast, other xTa-LLZO sintered pellets with lower Ta doping levels were short-circuited by lithium dendrites after polarization for much shorter time periods. The microstructure of the sintered body played a more essential role in lithium dendrite prevention compared to relative density alone. By characterizing the microstructure of xTa-LLZO sintered pellets, we proposed a formation mechanism of the pathways for lithium dendrite growth.

Micro-supercapacitors (micro-SCs) are significant micro-scale power sources and energy storage components for miniaturized electronic and flexible devices, where electrodes play a key role in determining their electrochemical performances. The efficient intercalation of ions between the stacking layers of two-dimensional layered materials (2DLM) makes them great candidates as thin-film electrodes in micro-SCs, where one can achieve much enhanced volumetric capacitance. However, a great challenge is to develop a high-yield production method for high-quality 2DLM thin-film electrodes. In this work, we have successfully reported a scalable fabrication process for free-standing black phosphorous (BP) thin films, derived from high-quality few-layer BP nanoflakes via a modified electrochemical exfoliation route, for flexible quasi-solid-state micro-SCs (QMSCs). The as-fabricated QMSCs exhibit an excellent stable electrochemical performance at a high scan rate of up to 100 V s^–1. More importantly, our QMSC device can not only achieve an outstanding energy density of 3.63 mW h cm^–3, a remarkable power density of 10.1 W cm^–3, and a superior cycle span (94.3% capacity retention even after 50 000 cycles), but also deliver excellent mechanical flexibility demonstrated by 91.3% capacity retention after 500 mechanical bending cycles. More interestingly, to meet the energy density and power density needs for various practical applications, multiple QMSCs can be successfully integrated in parallel or in series, which is demonstrated by lighting up of the red-light-emitting diode. The BP-based QMSCs can be patterned on a single substrate with flexible photodetectors based on same BP thin film to form a self-powered optoelectronic system.

Transition-metal dichalcogenides (TMDs) attract increased attention for the development of donor–acceptor materials enabling improved light harvesting and optoelectronic applications. The development of novel donor–acceptor nanoensembles consisting of poly(3-thiophene sodium acetate) and ammonium functionalized MoS₂ and WS₂ was accomplished, while photoelectrochemical cells were fabricated and examined. Attractive interactions between the negatively charged carboxylate anion on the polythiophene backbone and the positively charged ammonium moieties on the TMDs enabled in a controlled way and in aqueous dispersions the electrostatic association of two species, evidenced upon titration experiments. A progressive quenching of the characteristic fluorescence emission of the polythiophene derivative at 555 nm revealed photoinduced intraensemble energy and/or electron transfer from the polymer to the conduction band of the two TMDs. Photoelectrochemical assays further confirmed the establishment of photoinduced charge-transfer processes in thin films, with distinct responses for the MoS₂- and WS₂-based systems. The MoS₂-based ensemble exhibited enhanced photoanodic currents offering additional channels for hole transfer to the solution, whereas the WS₂-based one displayed increased photocathodic currents providing supplementary pathways of electron transfer to the solution. Moreover, scan direction depending on photoanodic and photocathodic currents suggested the existence of yet unexploited photoinduced memory effects. These findings highlight the value of electrostatic interactions for the creation of novel donor–acceptor TMD-based ensembles and their relevance for managing the performance of photoelectrochemical and optoelectronic processes.

Sacrificing sodium supply sources is needed for sodium-deficient cathode materials to achieve commercialization of sodium-ion full cells using sodium-ion intercalation anode materials. Herein, the potential of ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na) as a sacrificing sodium supply source was investigated by intimately blending it with sodium-deficient P2-type Na_0.67[Al_0.05Mn_0.95]O₂. The EDTA-4Na/Na_0.67[Al_0.05Mn_0.95]O₂ composite electrode unexpectedly exhibited an improved charge capacity of 177 mA h (g-oxide)⁻¹ compared with the low charge capacity of 83 mA h (g-oxide)⁻¹ for bare Na_0.67[Al_0.05Mn_0.95]O₂. The reversible capacity of an EDTA-4Na/Na_0.67[Al_0.05Mn_0.95]O₂//hard carbon full-cell system increased to 152 mA h (g-oxide)⁻¹ at the first discharge with a Coulombic efficiency of 89%, whereas the Na_0.67[Al_0.05Mn_0.95]O₂ without EDTA-4Na delivered a discharge capacity 51 mA h g^–1 because of the small charge capacity. The EDTA-4Na sacrificed itself to generate Na⁺ ions via oxidative decomposition by releasing four sodium ions and producing C₃N as a decomposition resultant on charge. It is thought that the slight increase in discharge capacity is associated with the electroconducting nature of the C₃N deposits formed on the surface of the Na_0.67[Al_0.05Mn_0.95]O₂ electrode. We elucidated the reaction mechanism and sacrificial activity of EDTA-4Na, and our findings suggest that the addition of EDTA-4Na is beneficial as an additional source of Na⁺ ions that contribute to the charge capacity.

Mg anode has pronounced advantages in terms of high volumetric capacity, resource abundance, and dendrite-free electrochemical plating, which make rechargeable Mg-based batteries stand out as a representative next-generation energy storage system utilized in the field of large-scale stationary electric grid. However, sluggish Mg²⁺ diffusion in cathode lattices and facile passivation on the Mg anode hinder the commercialization of Mg batteries. Exploring a highly electroactive cathode prototype with hierarchical nanostructure and compatible electrolyte system with the capability of activating both an anode and a cathode is still a challenge. Here, we propose a POM⊂MOF (NENU-5) core–shell architecture as a hybrid precursor template to achieve the stacking of tailored chalcogenide nanosheets around MoO₂-C conductive stakes, which can be employed as conversion–insertion cathodes (Cu_1.96S-MoS₂-MoO₂ and Cu₂Se-MoO₂) for Mg–Li dual-salt batteries. Li-salt modulation further activates the capacity and rate performance at the cathode side by preferential Li-driven displacement reaction in Cu⁺ extrusible lattices. The heterogeneous conductive network and conformal dual-doped carbon coating enable a reversible capacity as high as 200 mAh/g with a coulombic efficiency close to 100%. The composite cathode can endure a long-term cycling up to 400 cycles and a high current density up to 2 A/g. The diversity of MOF-based materials infused by functional molecules or clusters would enrich the nanoengineering of electrodes to meet the performance demand for future multivalent batteries.

Dual-absorber photoelectrodes have been proved to possess greater potential than the single-absorber systems in the applications of photoelectrochemical (PEC) cells (e.g., solar-driven water splitting); however, the mismatching of the energy bands and substantial carrier recombinations at the two absorber interfaces are normally subsistent. Here, we introduce an intermediate layer of conformal Al₂O₃ into the silicon/hematite (Si/α-Fe₂O₃) microwire photoanode for enriching the understanding of the interaction among the interlayer, inner absorber, and outer absorber. Our results show that the Si/Al₂O₃/α-Fe₂O₃ microwire photoanode with the thickness-optimized Al₂O₃ can lead to a substantial increase in the photocurrent from 0.83 to 2.08 mA/cm² at 1.23 V_RHE (under 1 sun irradiation) and an obvious decrease in the onset potential relative to the counterpart without Al₂O₃. By analyzing the PEC responses under various monochromatic lights, PEC impedance spectroscopy, and intensity-modulated photocurrent spectroscopy, we ascribe the improvements to the fact that the suitable-thickness Al₂O₃ can passivate the Si microwire surfaces and the bottom surfaces of the α-Fe₂O₃ film and give rise to Al doping into the post-synthesized α-Fe₂O₃. These essential causes promote the carrier separation in α-Fe₂O₃, diminish the photoanode surface recombination rate, and then increase the surface charge-transfer efficiency.

In this study, we introduced an efficient hybrid capacitive deionization (HCDI) system for removal of NaCl from brackish water, in which Prussian blue nanocubes embedded in a highly conductive reduced graphene oxide aerogel have been used as a binderfree intercalation anode to remove Na⁺ ions. The combination of redox-active nanocubes and the three-dimensional porous graphene network yielded a high salt removal capacity of 130 mg g^–1 at the current density of 100 mA g^–1. Moreover, energy recovery and energy consumption upon different desorption voltages of the HCDI system were investigated and the result showed a notably low energy consumption of 0.23 Wh g^–1 and a high energy recovery of 39%. Furthermore, the real-time intercalation process was verified by in situ X-ray powder diffraction measurements, which confirmed the intercalation and deintercalation processes during charging and discharging, respectively. Eventually, a perfect stability of the desalination unit was confirmed through the steady performance of 100 cycles. The improved efficiency as well as ease of fabrication opens a shiny horizon for our HCDI system toward commercialization of such technology for brackish water desalination.

A facile approach of in situ electrochemical oxidation has been utilized to modify carbons, including activated carbon, mesoporous few-layer carbon, graphite, carbon fiber, and carbon nanotube, which induces oxygen-containing functional groups on its surface and simultaneously enhances its wettability, contributing to the improvement of capacitance. By this approach, the capacitance of commercialized activated carbon is increased by 86% in an acidic electrolyte, reaching 320 F g^–1, of which more than 96% was maintained after 10 000 cyclic tests. The huge improvement stems from electrochemical redox reactions enabled by oxygen-associated groups, which do not adversely affect the porous structure and electrical conductivity. Such improvement will put carbon-based electrochemical capacitors into more practical application areas.

Nanowires have a wide range of applications, such as transparent electrodes, Li-ion battery anodes, light-emitting diodes, solar cells, and electronic devices. Currently, aluminum (Al) nanowires can be synthesized by thermally induced substitution of germanium (Ge) nanowires, chemical vapor deposition on other metal substrates, and template-assisted growth methods. However, there are still challenges in fabricating extremely high-purity nanowires, large-scale manufacturing, and simplifying the synthesis process and conditions. Here, we report for the first time that single-crystal Al nanowires can be one-step, in situ synthesized on a reduced graphene oxide (RGO) substrate on a large scale without using any catalysts. Through a simple high temperature treatment process, commercial micro-sized Al powders in RGO film were transformed into a single-crystal Al nanowire with an average length of 1.2 μm and an average diameter of 18 nm. The possible formation mechanism of the single-crystal Al nanowires is proposed as follows: hot aluminum atoms eject from the pristine aluminum/alumina core/shell structure of Al powders when they build up enough energy from the thermal stress under high temperature and confined space conditions, which is supported by both experimental and computational results. The method introduced here can be extended to allow the synthesis of one-dimensional highly reactive materials, like alkali metal nanowires, in confined spaces.

Solid electrolytes are the key to realize future solid-state batteries that show the advantages of high energy density and intrinsic safety. However, most solid electrolytes require long time and energy-consuming synthesis conditions of either extended ball milling or high-temperature solid-state reactions, impeding practical applications of solid electrolytes for large-scale systems. Here, we report a new and rapid liquid-based synthetic method for preparing a high-purity Li₇PS₆ solid electrolyte through the stoichemical reaction of Li₃PS₄ and Li₂S. This method relies on facile and low-cost solution-based soft chemistry to complete chemical reaction in extensively short time (2 h). The prepared Li₇PS₆ solid electrolyte shows a high phase purity, an impressive ionic conductivity (0.11 mS cm^–1), and a reasonable electrochemical stability with a metallic lithium anode. Our results highlight the use of an economic and nontoxic solvent to quickly synthesize a Li₇PS₆ solid electrolyte, which would promote the development of solid-state batteries for next-generation energy storage systems.

Solar cells based on organic–inorganic hybrid lead-halide perovskites are very promising because of their high performance and solution process feasibility. Elemental engineering on perovskite composition is a facile path to obtain high-quality crystals for efficient and stable solar cells. It was found that partially substituting I^– with Cl^– in the perovskite precursor promoted crystal growth, with the grain size larger than the layer thickness, and facilitated the generation of a self-passivation layer of PbI₂. Whereas the residual Cl^– ions were suspected to diffuse to the hole-transport layer consisting of ubiquitously spiro-OMeTAD, the formation of highly bounded ionic pairing of Cl^– with the oxidized state of spiro-OMeTAD led to insufficient charge extraction and severely reversible performance degradation. This issue was effectively alleviated upon Br^– doping owing to the generation of Pb–Br bonds in the lattice that strengthened the phase stability by improving the binding energy between each unit. The binary halide (Br^–/Cl^–)-doped perovskites resulted in a champion power conversion efficiency of 20.2% with improved long-term storage stability.

Porous poly(ionic liquid)s (PPILs) combine the features of porous materials, polymers, and ionic liquids (ILs) or their derivatives, but they are normally of amorphous structure with disordered pores. Here, we report the facile synthesis of ordered porous poly(ionic liquid) crystallines (OPICs, specialized as a kind of PPIL analogues) with diverse and adjustable framework IL moieties through the Schiff base condensation of IL-derived ionic salts and neutral monomers. Ternary monomer mixtures are employed to artistically control the chemical composition and pore configurations. Compact atomic packing was achieved to give spacing confined ionic surface with strong CO₂ affinity. Through monomer control, OPICs exhibit high CO₂ uptakes with excellent CO₂/N₂(CH₄) selectivities and efficiently implement CO₂ fixation through catalyzing epoxides cycloaddition under down to ambient conditions.

Nanomaterials are widely used as redox-type reaction catalysts, while reactant adsorption and O₂ activation are hardly to be promoted simultaneously, restricting their applications in many important catalytic fields such as preferential CO oxidation (CO-PROX) in H₂-rich stream. In this work, an interface-enhanced Co₃O₄–CuCoO₂ nanomesh was initially synthesized by a hydrothermal process using aluminum powder as a sacrificial agent. This nanomesh is systematically characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N₂ adsorption, X-ray photoelectron spectroscopy, UV–vis absorption spectroscopy, Raman spectroscopy, X-ray absorption near-edge spectroscopy, hydrogen temperature-programmed reduction, and oxygen temperature-programmed desorption. It is demonstrated that the nanomesh possesses high-density nanopores, enabling a large number of CO adsorption sites exposed to the surface. Meanwhile, electron transfer from O^2– to Co³⁺/Co²⁺ and the weakened bonding strength of Co–O bond at surfaces promoted the oxygen activation and redox ability of Co₃O₄. When tested as a catalyst for CO-PROX, this nanomesh with an optimized pore structure and a surface electronic structure, exhibits a strikingly high catalytic oxidation activity at low temperatures as well as a broader operation temperature window (i.e., CO conversion >99.0%, 100–200 °C) in the CO selective oxidation reaction. The present finding should be highly useful in promoting the quest for better CO-PROX catalysts, a hot topic for proton exchange membrane fuel cells and automotive vehicles.

The understanding of surface reactions at the electrode–electrolyte interfaces has been a longstanding challenge in Li-ion batteries. X-ray photoemission electron microscopy is used to throw light on the disputed aspects of the surface reactivity of high-energy Li-rich Li_1+x(Ni_aCo_bMn_1–a–b)_1–xO₂ (HE-NCM) cycled in an aprotic electrolyte against Li₄Ti₅O₁₂ (LTO). Despite the highly oxidative potential of 5.1 V vs Li⁺/Li, there is no formation of a layer of oxidized electrolyte byproducts on any of the cathode particles; instead, a homogeneous organic–inorganic layer builds up across the particles of the LTO anode due to the electrolyte and poly(vinylidene fluoride) binder decomposition on HE-NCM. In addition, such a layer incorporates, already from the first charge, micrometer-sized agglomerates of transition metals (TMs). The presence of TMs on the anode is explained by the instability of the reduced Mn, Co, and Ni formed at the surface of HE-NCM mainly during delithiation. The reduced TMs are unstable and prone to be transported to the LTO, where they get further reduced to metallic-like clusters. These results demonstrate that a dual reaction takes place at the HE-NCM–electrolyte interface if subject to high potential, namely, degradation of the surface structure and decomposition of the electrolyte, affecting directly the anode surface through the migration–diffusion processes.

Glucose-derived carbon/carbon nanotube (CNT) hybrid materials were prepared by hydrothermal carbonization of glucose in the presence of CNTs and subsequent carbonization, physical activation, or chemical activation. The proportion of CNTs added during the hydrothermal polymerization of glucose was varied to ascertain the optimum dose to maximize the performance of the carbon hybrids in supercapacitor applications. Both the thermal treatment applied and the addition of CNTs lead to changes in the textural and chemical properties of the activated carbons. It was observed that samples bearing CNTs exhibit higher number of nucleation centers for glucose oligomers to polymerize, and consequently, the behavior of the hydrothermal carbon toward activation differs according to the activating agent employed. Moreover, the initial chemical speciation dominated by acidic groups shifts to more basic functionalities (quinones and carbonyl groups) with the addition of CNTs. The effect of the different physicochemical properties of the prepared carbons on their electrochemical behavior was evaluated. The addition of 2 wt % of CNTs and subsequent chemical activation leads to electrode materials yielding 206 F g^–1 and 78% of capacitance retention up to 0.8 V and 20 A g^–1 and high rate cyclability (97% after 5000 cycles). The outstanding performance is ascribed to the high surface area, narrow mesopores, and phenol/carbonyl surface functionalities, which enhance molecular diffusion, the amount of stored energy, and electronic transportation, respectively.

In this paper, a direct sustainable approach for the development of a n-ZnO:p-CuO heterojunction (ZCH) through a simple grinding is reported to be an effective technique to enhance the piezoelectric performance of ZCH/polydimethylsiloxane (PDMS) nanocomposite-based nanogenerators (ZP-PNGs). We have first optimized the best concentration for ZnO/PDMS nanocomposite for the realization of the piezoelectric nanogenerator. Later, with the same configuration, we implemented a novel, simple, facile, frugal, and inexpensive technique to fabricate ZCH. The heterojunction results in the improved charge transfer characteristics, low capacitance, and charge nullification contributing to the enhanced piezoelectric output. This reflects in the improvement of the peak-to-peak piezoelectric potential of the device from 2.7 to 9 V. The instantaneous max power density was found to be 0.2 mW/m². The device can work as a force sensor with improved sensitivity of 1.7 V/N compared to 1.05 V/N of the intrinsic device. The device is being systematically studied for load matching and capacitor charging to demonstrate its practicability. Furthermore, we tested our device to harness the biomechanical energy from day-to-day life activities. Finally, the device was used to fabricate sustainable piezoelectric-based smart urinal systems for low-income group countries.

This paper describes the syntheses and electrochemical properties of a new niobate compound, aluminum niobate (AlNb₁₁O₂₉), for Li⁺ storage. AlNb₁₁O₂₉-microsized particles and nanowires were synthesized based on the solid-state reaction and solvothermal methods, respectively. In situ X-ray diffraction results confirmed the intercalating mechanism of Li⁺ in AlNb₁₁O₂₉ and revealed its high structural stability against cycling. The AlNb₁₁O₂₉ nanowires with a novel bamboo-like morphology afforded a large interfacial area and short charge transport pathways, thus leading to the observed excellent electrochemical properties, including high reversible Li⁺-storage capacity (266 mA h g^–1), safe operating potential (around 1.68 V), and high initial Coulombic efficiency (93.3%) at 0.1 C. At a very high rate (10 C), the AlNb₁₁O₂₉ nanowires still exhibited a capacity as high as 192 mA h g^–1, indicating their good rate capability. In addition, at 10 C, 96.3% capacity was retained over 500 cycles, indicating superior cycling stability. A full cell fabricated with AlNb₁₁O₂₉ nanowires as the anode and LiNi_0.5Mn_1.5O₄ microparticles as the cathode delivered a high energy density of 390 W h kg^–1 at 0.1 C. This work suggests that the AlNb₁₁O₂₉ nanowires hold a great promise for the development of high-performance lithium-ion batteries for large-scale energy-storage applications.

The United States Environmental Protection Agency (EPA) recognizes atrazine, a commonly used herbicide, as an endocrine disrupting compound. Excessive use of this agrochemical results in contamination of surface and ground water supplies via agricultural runoff. Efficient removal of atrazine from contaminated water supplies is paramount. Here, the mechanism governing atrazine adsorption in Zr₆-based metal–organic frameworks (MOFs) has been thoroughly investigated by studying the effects of MOF linkers and topology on atrazine uptake capacity and uptake kinetics. We found that the mesopores of NU-1000 facilitated rapid atrazine uptake saturating in <5 min and that the pyrene-based linkers offered sufficient sites for π–π interactions with atrazine as demonstrated by the near 100% uptake. Without the presence of a pyrene-based linker, NU-1008, a MOF similar to NU-1000 with respect to surface area and pore size, removed <20% of the exposed atrazine. These results suggest that the atrazine uptake capacity demonstrated by NU-1000 stems from the presence of a pyrene core in the MOF linker, affirming that π–π stacking is responsible for driving atrazine adsorption. Furthermore, NU-1000 displays an exceptional atrazine removal capacity through three cycles of adsorption–desorption. Powder X-ray diffraction and Brunauer–Emmett–Teller surface area analysis confirmed the retention of MOF crystallinity and porosity throughout the adsorption–desorption cycles.

Searching for high-performance electrode materials is one of the most effective ways to improve the energy density of current lithium-ion batteries. Using first-principles calculations, we reveal that pentagonal BN₂ (Penta-BN₂) can serve as a compelling anode material for lithium-ion batteries. Penta-BN₂ harbors intrinsic metallic nature before and after lithiation, showing excellent electrical conductivity. Significantly, the fully lithiated phase of Penta-BN₂ is Li₃BN₂, corresponding to an ultra-high theoretical capacity of 2071 mAh g^–1, superior to the capacity of most of the previously reported two-dimensional candidates. Meanwhile, the open-circuit voltage and diffusion barrier height of Penta-BN₂ are found to be fascinatingly low. Moreover, in light of its small Young’s modulus and robust lattice toward lithiation, Penta-BN₂ can accommodate volume changes during the charging–discharging processes, remarkably beneficial for fabricating flexible electrodes.

Improving catalytic performance of the oxygen reduction reaction (ORR) of Pt/C catalysts is essential for reducing Pt-loading and the according cost of proton exchange membrane fuel cells (PEMFCs). Herein, we report a new conceptual design of catalyst layers to improve the ORR performance of Pt/C catalysts by replacing perfluorosulfonated ionomers with protic poly(ionic liquid) as a proton conductor. The specific activity of the designed catalyst at 0.9 V under acidic conditions is over three times higher than that of catalyst using Nafion as the proton conductor. Furthermore, the durability test reveals that the introduction of protic poly(ionic liquid) ionomers can protect Pt nanoparticles against aggregation during potential cycles, but it is less durable than Nafion because of the nature of hydrocarbons. Nevertheless, we believe that replacing perfluorosulfonated ionomers with protic poly(ionic liquid) as proton conductors could be a promising strategy to design an efficient cathode for low Pt-loading PEMFCs.

We report the use of vinyl ethylene carbonate as a new solid electrolyte interface (SEI)-forming additive for Li-metal anodes in carbonate-based electrolyte, which has the advantages of both good storage performance and low price. Compared to the SEI formed in vinyl ethylene carbonate-free electrolyte, the SEI film formed in 10% vinyl ethylene carbonate electrolyte contains a higher relative content of polycarbonate species and a greater amount of decomposition products of LiPF₆ salt. Both components are expected to have positive effects on the passivation of Li-metal surface and the accommodation of volume changes of anode during cycling. Scanning electron microscopy images and COMSOL numerical simulation results further confirm that uniform Li deposition morphology can be achieved in the presence of vinyl ethylene carbonate additive. When cycling at the current density of 0.25 mA cm^–2 with a cycling capacity of 1.0 mAh cm^–2, the vinyl ethylene carbonate-contained Li–Cu cell exhibits a long life span of 816 h (100 cycles) and a relatively high Coulombic efficiency of 93.2%.

Depth-dependent growth of perovskite crystals remains challenging for high-performance perovskite solar cells made by a two-step spin-coating method. Effective morphology engineering approaches that enable depth-independent perovskite crystals growth and facile characterization technique to monitor subtle yet influential accompanying changes are urgently required. Here, a porous and intercrossed PbI₂–(CsI)_0.15 nanorods scaffold is prepared by integrating CsI incorporation with toluene dripping in ambient air, and the underlying mechanism is uncovered. With this porous scaffold and moisture-assisted thermal annealing, depth-independent growth of FA_0.85Cs_0.15PbI₃ is achieved, as evidenced in the photoluminescent (PL) spectra acquired by exciting the perovskite film from the top and bottom individually. It is of broad interest that PL spectroscopy is demonstrated as a sensitive technique to monitor the depth-dependent growth of perovskite. Moreover, the resulting inverted planar FA_0.85Cs_0.15PbI₃ perovskite solar cells deliver an efficiency of 16.85%, along with superior thermal and photostability. By incorporating 2% large-sized diammonium cation, propane-1,3-diammonium, the efficiency is further increased to 17.74%. Our work not only proposes a unique porous PbI₂–(CsI)_0.15 nanorods scaffold to achieve high-quality perovskite films in a two-step method but also highlights the distinctive advantage of PL spectroscopy in monitoring the depth-dependent quality of perovskite films.

Polyethylene hexasulfide (PEHS) is investigated as a cathode material in lithium batteries. By utilizing a condensation reaction, ethylene groups are inserted between six linear sulfurs in a chain to obtain PEHS while simultaneously exercising control over the polysulfur chain length. Additionally, by selecting a low-molecular-weight organic group, PEHS contains 87 wt % sulfur, thus maximizing the material-level specific capacity to 1217 mA h g^–1. Furthermore, this synthesis method is validated using a host of materials characterization techniques. In a battery, PEHS prevents the formation of soluble long-chain intermediates that plague traditional sulfur cathodes. This enables a high material-level capacity of 774 mA h g^–1 at 1C-rate alongside a stable performance over 350 cycles with a capacity fade rate of only 0.083% per cycle. We also elucidate the unique reaction pathway of our short-chain polysulfur material and provide a useful foundation for further development of sulfur-containing polymer-based cathode materials.

Triboelectric nanogenerators (TENGs) have been widely applied for energy harvesting and self-powered sensing, whereas smart deformable materials can be combined with the TENG to acquire a more intelligent and self-adaptive system. Here, based on the vapor-driven actuation material of a perfluorosulfonic acid ionomer (PFSA), we propose a type of humidity-responsive TENG. The integrated TENG array can automatically bend to the desired angles in response to different humidity conditions, and thus, it can effectively collect energy from both wind and rain drops, where the power density can reach 1.6 W m^–2 at a wind speed of 25 m s^–1 and 230 mW m^–2 under rainy conditions. Meanwhile, this TENG array can fully lay down in dry weather, using the reflective surface to reflect sunlight and heat radiation. The vapor absorption process of the PSFA film can also result in the charge accumulation process. Accordingly, relying on the strong absorption capability of PFSA, a TENG-based vapor sensor with high sensitivity has been developed for monitoring chemical vapor leakage and humidity change. This work opens up a promising approach for the application of the humidity-responsive materials in the field of energy harvesting and self-powered sensors. It can also promote the development of TENG toward a more intelligent direction.

Compared to chemosynthetic CuFeS₂, natural chalcopyrite (CuFeS₂) can be regarded as a promising anode material for exploring ultrafast and stable Li-ion batteries benefiting from it being firsthand, eco-friendly, and resource-rich. Considering the nonuniform size distribution in it and the fact that homogeneous grain distributions can effectively restrain the aggregation of active materials, the engineering of size is deemed an effective strategy to achieve excellent Li-storage performances. Herein, varisized natural CuFeS₂ are obtained by facial mineral processing technology and outstanding Li-storage performances are exhibited. Along with the decreasing of size, the contribution of pseudocapacitive as well as the ion transfer rates are significantly boosted. As expected, even at 1 A g^–1, a remarkable capacity of 1009.7 mA h g^–1 is displayed by the sample with the smallest size and most uniform distributions even after 500 cycles. Furthermore, supported by the detailed analysis of in situ X-ray diffraction and kinetic features, a hybrid of multiple lithium-metal sulfur systems and the major origin of the enhanced capacity upon long cycles are confirmed. Remarkably, this work is expected to increase the far-ranging applications of natural chalcopyrite as a firsthand anode material for lithium-ion batteries (LIBs) and inform the readers about the effects of particle size on Li-storage performances.

Methane is a potent greenhouse gas, with large emissions occurring across gas distribution networks and mining/extraction infrastructure. The development of inexpensive, low-power electrochemical sensors could provide a cost-effective means to carry out distributed sensing to identify leaks for rapid mitigation. In this work, we demonstrate a simple and cost-effective strategy to rapidly prototype ultrasensitive electrochemical gas sensors. A room-temperature methane sensor is evaluated which demonstrates the highest reported sensitivity (0.55 μA/ppm/cm²) with a rapid response time (40 s) enabling sub-ppm detection. Porous, laser-induced graphene (LIG) electrodes are patterned directly into commercial polymer films and imbibed with a palladium nanoparticle dispersion to distribute the electrocatalyst within the high surface area support. A pseudo-solid-state ionic liquid/polyvinylidene fluoride electrolyte was painted onto the flexible cell yielding a porous electrolyte, within the porous LIG electrode, simultaneously facilitating rapid gas transport and enabling the room temperature electro-oxidation pathway for methane. The performance of the amperometric sensor is evaluated as a function of methane concentration, relative humidity, and tested against interfering gases.

Photocatalytic reduction of CO₂ to renewable solar fuels is considered to be a promising strategy to simultaneously solve both global warming and energy crises. However, development of a superior photocatalytic system with high product selectivity for CO₂ reduction under solar light is the prime requisite. Herein, a series of nature-inspired Z-scheme g C₃N₄/FeWO₄ composites are prepared for higher performance and selective CO₂ reduction to CO as solar fuel under solar light. The novel direct Z-scheme coupling of the visible light-active FeWO₄ nanoparticles with C₃N₄ nanosheets is seen to exhibit excellent performance for CO production with a rate of 6 μmol/g/h at an ambient temperature, almost 6 times higher compared to pristine C₃N₄ and 15 times higher than pristine FeWO₄. More importantly, selectivity for CO is 100% over other carbon products from CO₂ reduction and more than 90% over H₂ products from water splitting. Our results clearly demonstrate that the staggered band structure between FeWO₄ and C₃N₄ reflecting the nature-inspired Z-scheme system not only favors superior spatial separation of the electron–hole pair in g-C₃N₄/FeWO₄ but also shows good reusability. The present work provides unprecedented insights for constructing the direct Z-scheme by mimicking the nature for high performance and selective photocatalytic CO₂ reduction into solar fuels under solar light.

In photodetection, the response time is mainly controlled by the device architecture and electron/hole mobility, while the absorption coefficient and the effective separation of the electrons/holes are the key parameters for high responsivity. Here, we report an approach toward the fast and highly responsive infrared photodetection using an n-type SnSe₂ thin film on a p-Si(100) substrate keeping the overall performance of the device. The I–V characteristics of the device show a rectification ratio of ∼147 at ±5 V and enhanced optoelectronic properties under 1064 nm radiation. The responsivity is 0.12 A/W at 5 V, and the response/recovery time constants were estimated as ∼57 ± 25/34 ± 15 μs, respectively. Overall, the response times are shown to be controlled by the mobility of the constituent semiconductors of a photodiode. Further, our findings suggest that n-SnSe₂ can be integrated with well-established Si technology with enhanced optoelectronic properties and also pave the way in the design of fast response photodetectors for other wavelengths as well.

The cost-effective production of flexible interconnects is a challenge in epidermal electronics. Here we report a low-cost approach for producing and patterning graphene films from polydimethylsiloxane films by direct laser scribing in ambient air. The produced graphene films exhibit high electrical conductivity and excellent mechanical properties and can thus be used directly as a flexible conductive layer without the need for metals. The skinlike pressure sensor with these layers exhibits ultrahigh sensitivity (∼480 kPa^–1) while maintaining the fast response/relaxation time (2 μs/3 μs) and excellent cycle stability (>4000 repetitive cycles). Moreover, it can naturally attach to the skin to monitor the wrist pulse. In addition, a 7 × 7 sensor array has been fabricated, which possesses the capability to detect the spatial distribution of pressure. This device has great potential for application in epidermal electronics because of its low cost and high performance.

Synthetic micro/nanomotors fueled by glucose are highly desired for numerous practical applications because of the biocompatibility of their required fuel. However, currently all of the glucose-fueled micro/nanomotors are based on enzyme-catalytic-driven mechanisms, which usually suffer from strict operation conditions and weak propulsion characteristics that greatly limit their applications. Here, we report a highly efficient glucose-fueled cuprous oxide@N-doped carbon nanotube (Cu₂O@N-CNT) micromotor, which can be activated by environment-friendly visible-light photocatalysis. The speeds of such Cu₂O@N-CNT micromotors can reach up to 18.71 μm/s, which is comparable to conventional Pt-based catalytic Janus micromotors usually fueled by toxic H₂O₂ fuel. In addition, the velocities of such motors can be efficiently regulated by multiple approaches, such as adjusting the N-CNT content within the micromotors, glucose concentrations, or light intensities. Furthermore, the Cu₂O@N-CNT micromotors exhibit a highly controllable negative phototaxis behavior (moving away from light sources). Such motors with outstanding propulsion in biological environments and wireless, repeatable, and light-modulated three-dimensional motion control are extremely attractive for future practical applications.

Inkjet printing of functional inks on textiles to embed passive electronics devices and sensors is a novel approach in the space of wearable electronic textiles. However, achieving functionality such as conductivity by inkjet printing on textiles is challenged by the porosity and surface roughness of textiles. Nanoparticle-based conductive inks frequently cause blockage/clogging of inkjet printer nozzles, making it a less than ideal method for applying these functional materials. It is also very challenging to create a conformal conductive coating and achieve electrically conductive percolation with the inkjet printing of metal nanoparticle inks on rough and porous textile and paper substrates. Herein, a novel reliable and conformal inkjet printing process is demonstrated for printing particle-free reactive silver ink on uncoated polyester textile knit, woven, and nonwoven fabrics. The particle-free functional ink can conformally coat individual fibers to create a conductive network within the textile structure without changing the feel, texture, durability, and mechanical behavior of the textile. It was found that the conductivity and the resolution of the inkjet-printed tracks are directly related with the packing and the tightness of fabric structures and fiber sizes of the fabrics. It is noteworthy that the electrical conductivity of the inkjet-printed conductive coating on pristine polyethylene terephthalate fibers is improved by an order of magnitude by in situ heat-curing of the textile surface during printing as the in situ heat-curing process minimizes the wicking of the ink into the textile structures. A minimum sheet resistance of 0.2 ± 0.025 and 0.9 ± 0.02 Ω/□ on polyester woven and polyester knit fabrics is achieved, respectively. These findings aim to advance E-textile product design through integration of inkjet printing as a low-cost, scalable, and automated manufacturing process.

Because of the similarity of odor, appearance, and chemical structure of methanol and ethanol, measuring the low concentration of methanol in an alcoholic beverage is difficult to perform in a quick, quantitative, and repeatable fashion. However, it is important for people to monitor the content of methanol in a liquor because a high amount of methanol absorbed will result in blindness, coma, and death. In response to this need, we have developed electrolyte-free methanol electrolysis and ethanol electrolysis based on the nanogap electrochemical cells for the methanol and ethanol sensing. Upon applying a voltage, a high electric field across the nanogap cell enhances the solution ionization and the ion transport rate. Moreover, the nanoscale distance between the electrodes provides a shorter path for electrolysis to easily occur. The nanogap electrochemical cells not only make the direct electrolyte-free organic solvent electrolysis possible but also enhance the sensitivity of the chemical of interest in low-concentration solutions without the influence of the added electrolyte. The nanogap electrochemical cells have been demonstrated having high sensitivity to detect 0.15% methanol volume concentration in deionized water solutions without adding any electrolyte, and its ability for the fake alcoholic beverages’ detection has successfully demonstrated.

Epitaxial ferroelectric Hf_0.5Zr_0.5O₂ films have been successfully integrated in a capacitor heterostructure on Si(001). The orthorhombic Hf_0.5Zr_0.5O₂ phase, [111] out-of-plane oriented, is stabilized in the films. The films present high remnant polarization P_r close to 20 μC/cm², rivaling with equivalent epitaxial films on single crystalline oxide substrates. Retention time is longer than 10 years for a writing field of around 5 MV/cm, and the capacitors show endurance up to 10⁹ cycles for a writing voltage of around 4 MV/cm. It is found that the formation of the orthorhombic ferroelectric phase depends critically on the bottom electrode, being achieved on La_0.67Sr_0.33MnO₃ but not on LaNiO₃. The demonstration of excellent ferroelectric properties in epitaxial films of Hf_0.5Zr_0.5O₂ on Si(001) is relevant toward fabrication of devices that require homogeneity in the nanometer scale, as well as for better understanding of the intrinsic properties of this promising ferroelectric oxide.

Schottky barrier height (SBH) engineering of contact structures is a primary challenge to achieve high performance in nanoelectronic and optoelectronic applications. Although SBH can be lowered through various Fermi-level (FL) unpinning techniques, such as a metal/interlayer/semiconductor (MIS) structure, the room for contact metal adoption is too narrow because the work function of contact metals should be near the conduction band edge (CBE) of the semiconductor to achieve low SBH. Here, we propose a novel structure, the metal/transition metal dichalcogenide/semiconductor structure, as a contact structure that can effectively lower the SBH with wide room for contact metal adoption. A perpendicularly integrated molybdenum disulfide (MoS₂) interlayer effectively alleviates FL pinning by reducing metal-induced gap states at the MoS₂/semiconductor interface. Additionally, it can induce strong FL pinning of contact metals near its CBE at the metal/MoS₂ interface. The technique using FL pinning and unpinning at metal/MoS₂/semiconductor interfaces is first introduced in the MIS scheme to allow the use of various contact metals. Consequently, significant reductions of the SBH from 0.48 to 0.12 eV for GaAs and from 0.56 to 0.10 eV for Ge are achieved with several different contact metals. This work significantly reduces the dependence on contact metals with lowest SBH and proposes a new way of overcoming current severe contact issues for future nanoelectronic and optoelectronic applications.

Colloidal quantum dots (QDs) are promising optical and optoelectronic materials for various applications. The excited state properties are important indexes to assess the quality of QDs and may directly affect their applications. Different from controlling surface engineering (surface ligands, shell thickness, etc.) to adjust excited state properties, high-quality shell-free alloyed CdSe_1–xS_x (simplified as CdSeS) QDs with controlled excited state properties were synthesized by tuning the composition and using diphenylphosphine as a beneficial additive at a low temperature (∼180 °C). The optimized CdSeS shell-free alloyed QDs (Se/S = 1:8) exhibited excellent optical properties with tuning of the excited state, including single-exponential photoluminescence (PL) decay dynamics, a narrow full width at half maximum of 28 nm, and non-blinking emission behavior (>98% “on” time). Furthermore, all-solution-processed, multilayered quantum dot light-emitting diodes were fabricated using the conventional device structure to assess the performance of QDs with composition-controlled excited states. The best device displayed a maximum luminance of 92,330 cd m^–2, a current efficiency of 50.3 cd A^–1, and an external quantum efficiency of 14.5%.

Efficient, stable electrode catalysts and advanced hydrogen sensing materials are the core of the hydrogen production and hydrogen detection for guaranteeing the safe issues. Although a universal material to achieve the above missions is highly desirable, it remains challenging. Here, we report palladium/bismuth/copper hierarchical nanoarchitectures (Pd/Bi/Cu HNAs) for advanced dual-applications toward hydrogen evolution reaction (HER) and hydrogen detection, via first electrodeposition of cylindrical nanowires and subsequent wet-chemical etching art. For HER, the Pd/Bi/Cu HNAs present the overpotential (79 mV at 10 mA^–2) and tafel slope (61 mV dec^–1) closing to those of Pt/C. For hydrogen detection, the Pd/Bi/Cu HNAs was able to work at a wide-temperature range (∼156–418 K), and remarkably, their critical temperature (∼156 K) of the “reversing sensing behavior” is much lower than that of pure Pd nanowires (278 K). These excellent performances are ascribed to the synergic effect of hierarchical morphology induced more exposure of Pd, and the Pd d-band modification via Cu and Bi dopants. It is feasible that Pd/Bi/Cu HNAs serve as universal materials for both efficient catalysts toward hydrogen evolution via water electrolysis and wide-temperature adapted hydrogen detection.

Recently, multifunctional devices printed on flexible substrates, with multisensing capability, have found new demand in practical fields of application, such as wearable electronics, soft robotics, interactive interfaces, and electronic skin design, revealing the vital importance of precise control of the fundamental properties of metal oxide nanomaterials. In this paper, a novel low-cost and scalable processing strategy is proposed to fabricate all-printed multisensing devices with UV- and gas-sensing capabilities. This undertaken approach is based on the hierarchical combination of the screen-printing process and laser irradiation post-treatment. The screen-printing is used for the patterning of silver interdigitated electrodes and the active layer based on anatase TiO₂ nanoparticles, whereas the laser processing is utilized to fine-tune the UV and ethanol-sensing properties of the active layer. Different characterization techniques demonstrate that the laser fluence can be adjusted to optimize the morphology of the TiO₂ film by increasing the contribution from volume porosity, to improve its electrical properties and enhance its UV photoresponse and ethanol-sensing characteristics at room temperature. Furthermore, results of the UV and ethanol-sensing investigation show that the optimized UV and ethanol sensors have good repeatability, relatively fast response/recovery times, and excellent mechanical flexibility.

In medical applications, two-dimensional nanomaterials have been widely studied on account of their intriguing properties such as good biocompatibility, stability, and multifunctionality. Herein, an ultrathin MnO₂ nanosheet has been fabricated by a simplistic hydrothermal process. The high photothermal conversion performance (62.4%) can be attributed to the vacancy in the ultrathin MnO₂ nanosheet, as confirmed by the extended X-ray absorption fine structure results and the density functional theory calculation, benefiting photoacoustic imaging-guided cancer therapy. This highly efficient vacancy-induced photothermal therapy has been reported for the first time. As a result, this work demonstrates that this ultrathin MnO₂ nanosheet has a potential to construct a nanosystem for imaging-guided cancer therapy.

We demonstrate that hole injection from a top electrode composed of Au nanoparticles (AuNPs) capped with a thick Au layer into an underlying organic semiconductor, N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4′-diamine (DNTPD), is significantly enhanced compared to that in a control device whose top electrode is composed entirely of a thick Au layer. The fabrication of this organic hole-only device with the AuNP electrode is made possible by dry, room-temperature distribution of AuNPs onto DNTPD using a spark-discharge aerosol technique capable of varying the average diameter (D̅) of the AuNPs. The enhancement in hole injection is found to increase with decreasing D̅, with the current density of a device with D̅ = 1.1 nm being more than 3 orders of magnitude larger than that of the control device. Intensity-modulated photocurrent measurements show that the built-in potentials of the devices with the AuNP electrode are smaller than that of the control device by as much as 0.68 V, indicating that the enhanced hole injection originates from the increased work functions of these devices, which in turn decreases the hole injection barrier heights. X-ray photoelectron spectroscopy reveals that the increased work functions of the AuNP electrodes are due to surface oxidation of the AuNPs resulting in AuN and Au₃N. The degree of oxidation of the AuNPs increases with decreasing D̅, consistent with the D̅-dependencies of the hole injection enhancement and the built-in potential reduction.

Diketopyrrolopyrrole–ethynylene-bridged porphyrin dimers are capped with electron-deficient 3-ethylrhodanine (A₂) via a π-bridge of phenylene ethynylene, affording two new acceptor–donor–acceptor structural porphyrin dimers (DPP-2TTP and DPP-2TP) with strong absorption in ranges of 400–550 nm (Soret bands) and 700–900 nm (Q bands). Their intrinsic absorption deficiency between the Soret and Q bands could be perfectly compensated by a wide-bandgap small molecule DR3TBDTTF (D*) with absorption at 500–700 nm. Impressively, the optimal ternary device based on the blend films of DPP-2TPP, DR3TBDTTF (20 wt %), and PC₇₁BM shows a PCE of 11.15%, whereas the binary devices based on DPP-2TTP/PC₇₁BM and DPP-2TP/PC₇₁BM blend films exhibit PCEs of 9.30 and 8.23%, respectively. The high compatibility of the low bandgap porphyrin dimers with the wide-bandgap small molecule provides a new threesome with PC₇₁BM for highly efficient panchromatic ternary organic solar cells.