Aluminum-air batteries (AABs) are positioned as next-generation electrochemical energy storage systems, boasting high theoretical energy density, cost-effectiveness, and a lightweight profile due to aluminum’s abundance. This review evaluates the latest advancements in AABs, emphasizing breakthroughs in anode optimization, electrolyte formulation, and cathode material development to enhance performance and scalability for practical applications. Anode improvements, including alloying and surface treatments, reduce parasitic corrosion and improve anode stability, addressing prevailing challenges such as hydrogen evolution and rapid capacity fade. Electrolyte innovations, particularly hybrid systems integrating ionic liquids or neutral salts, are shown to mitigate electrolyte-induced anode degradation while ensuring high ionic conductivity. Meanwhile, advancements in air-breathing cathodes, employing cost-effective materials like doped carbon, transition metal oxides/sulfide, and metal organic framework-derived catalyst, improve oxygen reduction/evolution reaction kinetics and durability, critical for the extended lifespan and efficiency of AABs. These developments collectively enhance AABs viability for applications in electric vehicles and renewable energy storage, highlighting the strategic integration of materials science and electrochemical engineering to address longstanding technical barriers. AABs are thus positioned as viable candidates in the pursuit of sustainable, high-capacity, and long-lasting energy solutions for the future.

Dual-atom catalysts (DACs) have gained great attention as highly efficient materials for the hydrogen evolution reaction (HER) due to their synergistic dual-site effects and high atomic utilization. This review explores how microenvironmental regulation, including electronic structure optimization and coordination design, influences DAC performance. Both homonuclear and heteronuclear types of DACs are analyzed in detail in terms of their site interactions and structural configurations. Moreover, recent advancements of DACs in HER applications under various pH conditions are discussed, highlighting their enhanced catalytic activity and mechanism. Despite challenges in synthesis and characterization, DACs represent a promising frontier for developing efficient HER catalysts and offer guidance for future research and scalable applications.

Lithium-mediated nitrogen reduction (LNRR) shows promise for sustainable NH₃ production, but flow electrolyzers incorporating gas-diffusion electrodes (GDEs) have rarely been studied toward this application. This work investigates cathode GDEs using inexpensive carbonaceous reaction layers to achieve stable and active NH₃ electrosynthesis for over 8 h under pulsed currents. Particularly, the amorphous C45 demonstrates superior durability over Vulcan, Vulcan-supported Pt, and graphitic SFG6L at −5 mA cm^–2. Replacing Nafion with polyvinylidene fluoride as the binder improves the NH₃ production rate (3.11 ± 0.41 μmol h^–1 cm^–2) and Faradaic efficiency (5.0 ± 0.65%), outperforming prior precious-metal-free cathode results.

Liquid ammonia electrolysis is a promising route to generate hydrogen. It is performed at room temperature to obtain highly purified hydrogen isolated at the cathode. Theoretically, hydrogen can be extracted by electrolyzing liquid ammonia at a voltage of 0.077 V vs H₂/NH₃ at 25 °C. However, the onset voltage exceeds the theoretical value in practice owing to the high overpotential associated with the anodic reaction in the amide ion oxidation process. In this study, we prepared high entropy alloy IrRhRuCoNi powder to serve as an anodic catalyst. This powder exhibited a high specific surface area (66.2 m²/g) and was synthesized by reducing the oxide precursor in molten LiCl–CaH₂ at 600 °C. A comprehensive structural analysis involving X-ray diffraction and scanning/transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy revealed that the synthesized powder consisted primarily of a face-centered cubic structure with a well-dispersed mixture of Ir, Rh, Ru, Co, and Ni at the nanoscale. The IrRhRuCoNi powder was then supported on carbon nanotubes and used as an anodic catalyst in liquid ammonia electrolysis. Chronoamperometry measurements demonstrated that the anodic catalyst exhibited current densities comparable to a commercial ruthenium black catalyst, reaching 0.93/4.20 mA/cm² at 0.3/0.5 V vs H₂/NH₃ after 300 s. Furthermore, the catalytic performance remained stable over a 50 h period. Notably, the alloyed catalyst maintained high current densities of 1.03/3.50 mA/cm² at 0.3/0.5 V vs H₂/NH₃ even during cyclic voltammetry measurements at an exceptionally slow scan rate of 2 mV/min from 0 to 0.5 V vs H₂/NH₃. In contrast, the commercial ruthenium black catalyst exhibited substantial decreases in current densities under these conditions. These results demonstrate the superior performance of the synthesized high entropy alloy IrRhRuCoNi catalyst for liquid ammonia electrolysis compared to the single Ru catalyst, which is likely attributed to the synergistic effects arising from the multielemental composition.

Polyzwitterionic (polyZI) ionogels have been demonstrated to be promising candidates for battery electrolyte applications. In this study, we used atomistic molecular dynamics simulations to study the influence of alkali metal cation (Li⁺ or Na⁺) and anion (BF4−, PF6−, TFS^–, and TFSI^–) chemistry on the dynamic and structural properties of poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] supported ionic liquid electrolytes. With an increase in the poly(MPC) content, our simulations revealed a decrease in the diffusivities and conductivities in both the Li⁺ and Na⁺ ionogels. With the increasing polyZI content, the results show a simultaneous increase in the inverse Haven ratios and transference numbers. While varying the anion identities, our findings indicate that chemistries in which a higher fraction of alkali metal cations coordinate with the polymers result in enhanced inverse Haven ratios, while systems with stronger alkali metal cation–polyZI interactions exhibit improved transference numbers. Overall, our results shed light on the complex nature and influence of the electrostatic interactions between the polyZI, ionic liquid, and salt ions on the mobility and structural properties of polyZI ionogels.

An extensive exploration of the chemical space was conducted to design and identify promising multicomponent cubic alloys with appropriate enthalpy of reaction for hydrogen storage applications. We aim to identify alloys with suitable hydrogen absorption conditions for ambient conditions, according to favorable thermodynamic criteria, while addressing computational challenges in modeling large-scale systems. 18 elements were selected, leading to the systematic investigation of over 8000 quinary alloy systems across four distinct crystal phases (within solid–solution alloys, mono- and dihydrides). This effort resulted in a comprehensive data set of more than 34,000 equimolar MH_x structures, where M represents a combination of 5 elements chosen among the 18 selected atoms. To handle the computational demands of density functional theory (DFT) calculations on such a large scale of disordered supercells designed by the special quasirandom structure (SQS) method, a machine learning (ML) approach was introduced to accurately predict the enthalpy of hydride formation. By training the ML model on a strategically chosen subset of the data, high predictive accuracy was achieved while significantly reducing computational costs. By applying filtering parameters constrained by thermodynamic considerations, such as the value of plateau pressure or the presence of a single plateau, the integrated DFT-SQS-ML framework successfully identified 568 quinary alloy systems as ideal candidates for hydrogen storage. The findings establish a solid foundation for experimental validation and further advancements in the field of hydrogen storage materials.

This research focuses on the influence of grain size and boundaries on hydrogen diffusion in thin films and powders. The isoconversion kinetic method was applied to investigate the hydrogen desorption properties of Mg–Ni–H thin films and powders. The desorption behavior of Mg–Ni–H films was monitored using in situ optical microscopy and thermal desorption spectroscopy (TDS). In situ investigation of hydrogen release provided valuable insights into heterogeneous nucleation in thin films. The TDS curves of crystalline Mg–Ni–H indicate that desorption occurs in a one-step process, starting at T_onset = 212 °C, with the peak maximum observed at T_des = 250 °C. The apparent activation energy for the crystalline sample was estimated to be 52.1 ± 0.6 kJ/mol. These findings suggested that the desorption mechanism is strongly influenced by the grain size and the density of defects, such as the grain boundaries. Powders are prepared by mechanical milling of MgH₂ with Ni, maintaining the same molar ratio as in the preparation process of thin films. Four samples were prepared with different milling times ranging from 30 min to 2 h. The temperature-programmed desorption coupled with mass spectroscopy (TPD-MS) was used to analyze the prepared powders. Milling-induced defects in the MgH₂ crystal structures, combined with the uniform distribution of the catalytic phase, significantly impacted hydrogen desorption kinetic and reduced the desorption temperature by 2 times. In this paper, we compare the amorphous vs the crystalline state, highlighting how the material’s morphology controls the thermodynamics, while the amount and position of defects within the crystal structure influence the desorption kinetics.

Perovskite solar cell devices, composed of solution-processed perovskite layers with thicknesses of a few hundred angstroms, represent a leading technology in thin-film photovoltaics. Here, we performed a theoretical investigation based on ab initio calculations to explore the role of perovskite thin film thickness, with the general formula FPEA₂(MA_n–1)Pb_nI_3n+1, where FPEA represents 4-fluorophenylethylammonium cations and n ranges from 1 to 4 layers. Our findings reveal that increasing the thickness of the inorganic layer significantly influences the structural, energetic, and optoelectronic properties. Enhanced charge transfer within the inorganic framework and stronger organic–inorganic interactions are observed as the effective charge distribution shifts with increasing thickness. Exothermic trends in adsorption and interaction energies highlight the stabilizing effects of van der Waals forces and hydrogen bonding. The PbI₆-octahedra play a critical role in determining the optical activity and the formation of valence and conduction bands. Thicker films exhibit more intense absorption, emphasizing the importance of PbI₆-octahedra in driving optical properties. Moreover, the work function (ϕ) decreases with increasing thickness due to reduced quantum confinement effects, while the nature of polar FPEA molecules induces deviations in ϕ, underscoring the interaction between molecular composition and thickness. Band alignment further reveals strong spin–orbit coupling effects on the conduction band minimum (CBM), influenced by charge-transfer variability from FPEA to halides. These findings provide insights into thickness-dependent properties that are essential for optimizing perovskite-based devices.

In traditional carbonate electrolytes, lithium mobility is limited owing to the strong solvation effect between lithium ions and solvent sheaths. As a result, the lithium-ion transference number (t_Li⁺) is lower than 0.5 (mostly between 0.2 and 0.4), which indicates that anion transference is dominant in electrolyte’s charge conduction. In order to enhance lithium mobility in electrolytes, a low-polarity organic boron compound, mesityldimethoxyborane (MDMB), was added to conventional carbonate electrolytes to increase lithium-ion mobility. Two electrolyte systems with different MDMB ratios exhibited high t_Li⁺ as 0.93 for 111 (EC:DEC:MDMB = 1:1:1, volume ratio) and 0.86 for 112 (EC:DEC:MDMB = 1:1:2). Moreover, the stability of LiNMC cathodic half-cell was also improved by using 111 and 112 which form robust B-rich CEI. The activation energy for lithiation and resistance of CEI were decreased by MDMB. The durability of LiNMC cathodic half-cell was enhanced substantially under 1C CCCV mode. Cells with 111 and 112 electrolyte systems underwent more than twice as many cycles as conventional electrolytes.

Using both experimental and computational approaches, we have demonstrated a major enhancement of electrocatalytic activity for both half-reactions of water splitting, i.e., the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline conditions, through the incorporation of oxygen vacancies in the perovskite oxide La₂FeNiO₆ (LaFe_0.5Ni_0.5O₃). Density functional theory (DFT) calculations predicted that the incorporation of oxygen vacancies would lead to the reinforcement of several electronic parameters, namely, the proximity of the d-band center to the Fermi level, closer separation between p and d bands, and greater hybridization of those bands, all of which are known to be descriptors of electrocatalytic properties. Therefore, DFT simulations predicted that the electrocatalytic activity should be enhanced due to the presence of oxygen vacancies. This was thoroughly confirmed by the experiment, where the reduced material containing oxygen vacancies, termed LaFe_0.5Ni_0.5O₃-R, showed remarkably lower overpotentials for both HER and OER. This was particularly notable for OER, where the overpotential decreased by nearly 100 mV, reaching η₁₀ = 330 mV, comparable to those of noble metal catalysts such as IrO₂ and RuO₂. In addition, for both HER and OER, the mass activity and reaction kinetics were enhanced upon the creation of oxygen vacancies. Furthermore, a significant increase in turnover frequency (TOF), by nearly 8-fold, was achieved. In addition, electrochemical impedance spectroscopy indicated that the charge-transport properties were enhanced, leading to facile electron transfer for both HER and OER. The excellent match between computational predictions and experimental results is notable.

Nowadays, battery separators play a critical role in determining the sustainability, electrochemical efficiency, and safety of lithium-ion batteries (LIBs). In this contribution, we developed fire-resistant composite membranes called CelloMOF by in situ grafting of metal-organic framework, ZIF-67, onto phosphorylated cellulose nanofibers (P-CNFs) followed by a vacuum filtration process akin to papermaking. The hybrid ZIF-67@P-CNF membrane exhibits superior properties than a polyolefin-based commercial separator (CS) in terms of enhanced thermal and dimensional stability, flame-retardant properties, better surface wettability, and improved electrolyte uptake. Thermal dimensional stability tests revealed that the ZIF-67@P-CNF separator maintained its structure even at 200 °C, whereas CS suffered severe shrinkage, potentially leading to internal short circuits. Combustion tests showed a peak heat release rate (PHRR) of 34.5 W/g and a total heat release (THR) of 1.61 kJ/g for ZIF-67@P-CNF, significantly lower than the PHRR (1111.82 W/g) and THR (40.89 kJ/g) of CS. The composite separator also demonstrated significantly improved wettability, with a contact angle of 32 ± 1.04°, compared to 92 ± 1.07° for CS, highlighting its hydrophilic nature. Electrochemical evaluations in LiFePO₄/Li half-cells indicated a higher discharge capacity of 149 mA h g^–1 at 0.2 C and superior capacity retention of 86% after 50 cycles, outperforming CS (145 mA h g^–1 and 84%, respectively). These results underscore the potential of the ZIF-67@P-CNF membrane to advance safe, high-performance LIBs by addressing critical challenges in thermal stability, flame retardancy, and electrolyte compatibility.

Li–Ni–Mn-O spinel cathode materials operating at ∼5 V vs Li⁺/Li appear to be very interesting alternatives to Co-containing layered materials in terms of rate capability, energy and power densities, and sustainability of material resources. Nevertheless, their high operating voltage, which has been an asset to date, does not allow them to be used with conventional carbonate-based electrolytes. The latter undergoes spontaneous oxidation when in contact with the charged electrode, resulting in a reduction of the cathode material, an imbalance in the Li-ion system, and a subsequent rapid loss of capacity. This incompatibility could be overcome by creating a stable, electronically insulating solid interphase at the surface of the composite electrode. Here, we report the direct deposition of lithium fluoride (LiF) on LNMO electrodes by atomic layer deposition (ALD). LiF prepared with a specific combination of precursors (lithium bis(trimethylsilyl)amide and titanium tetrafluoride) has a total impurity content of less than 2% in the bulk. In addition, to enable direct coating by ALD on the positive electrode, a commonly used binder (polyvinylidene fluoride) was replaced with polyimide (PI), a more thermally stable and nonfluorinated polymer. Using X-ray photoelectron spectroscopy (XPS) and electrochemical analysis, we demonstrate the excellent thermal stability of this LNMO/PI electrode up to 300 °C as well as its electrochemical and chemical stability in a standard carbonate electrolyte. Electrochemical data show that LiF extends the cycle life of the LNMO/PI half-cell at a high C-rate (1C). The LiF layer has been proven to be stable on the pristine electrode upon prolonged exposure to the electrolyte. However, when charged at a low C-rate, the layer exhibits a tendency to disappear. The reasons for this behavior are not yet clear but could be linked to the degradation reactions in the electrolyte or to the local concentration changes.

The growing demand for efficient energy storage systems to support the global transition to renewable energy has intensified interest in zinc–air batteries (ZABs), which are renowned for their high theoretical energy density. However, the limited performance of oxygen reduction (ORR) and oxygen evolution (OER) reactions remains a significant challenge. In this study, we present a bifunctional catalyst, La_0.90Ce_0.10Co_0.67Ni_0.33O₃ (LCCNO), designed with a three-dimensional ordered macroporous (3DOM) structure. The introduction of both Ce and Ni into LaCoO₃ shifts the O 2p and M 3d-band centers closer to the Fermi level, thereby improving the electrical conductivity and optimizing metal–oxygen hybridization, which significantly boosts the OER and ORR activity. The 3DOM LCCNO catalyst demonstrates an OER overpotential of 405 mV at 10 mA cm^–2, an ORR half-wave potential of 0.61 V vs RHE, and a ΔE_OER–ORR of 1.02 V, a significant improvement over pristine LaCoO₃. In ZABs, 3DOM LCCNO achieves a 42% higher power density and 68% enhanced stability relative to LaCoO₃, underscoring its potential as a high-performance bifunctional catalyst for advanced energy storage applications.

Seawater electrolysis for hydrogen production has emerged as a focal point in hydrogen energy utilization technology due to its low carbon emissions and the abundance of seawater resources. However, the high chlorine content of seawater as an electrolyte negatively impacts the stability and performance of anodic catalysts. Herein, we design a silver integration strategy to repel surface Cl^– adsorption and modulate the electronic structure of the metal active center of NiCo bimetallic metal organic framework (MOF). The obtained Ag@NiCo MOF achieves an overpotential of 269 mV at a current density of 10 mA cm^–2 toward oxygen evolution reaction (OER) and maintains this performance over 500 h in simulated alkaline seawater without obvious degradation. The superior performance is because the in-phase electronic interaction induced by deposited Ag optimizes the electron state of MOF metal active sites. Moreover, deposited Ag in situ transforms into AgCl during OER further triggering the repulsion of Cl^– on the electrode surface. This not only facilitates the reaction kinetic but also helps repel chloride ions and enhances electrode stability and the selectivity for OER. The superior electrochemical performance and stability of Ag@NiCo MOF render them highly competitive among various catalysts for alkaline seawater spitting.

Adopting three-dimensional (3D) scaffolds onto lithium metal anode has emerged as a promising strategy to improve the charge/discharge stability of next-generation high-energy-density lithium metal batteries (LMBs). However, the undesirable growth of Li dendrites on the scaffold’s surface and their high-cost fabrication methods remain challenging. To address these issues, herein, a functional 3D scaffold employing a lithiophilic Ag concentration gradient (3D Ag@Cu) is designed, which can be prepared via a simple galvanic displacement. The lithiophilic Ag reacts with Li to form a solid solution, reducing the Li nucleation overpotential and promoting uniform Li deposition. Furthermore, the Ag-gradient structure facilitates the bottom-up growth of Li within the scaffold, maximizing the use of the internal space. Consequently, a full-cell equipped with the 3D Ag@Cu scaffold demonstrated higher cycling stability (89.03% capacity retention after 110 cycles) and rate performance (65.6% capacity retention at 2 C) compared to both LMBs with the planar Cu foil and the bare 3D Cu scaffold.

The efficiency of mixed lead–tin perovskite solar cells has increased rapidly, thanks to efficient passivation strategies of bulk and interfacial defects. For example, this occurs at the hole-transport layer and the perovskite interface. Here, we compare the self-assembled monolayers and multilayers (SAMs), [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and methylphosphonic acid (MPA), to a PEDOT:PSS layer at the rear interface of a MA-free narrow band gap perovskite in single-junction (SJ) and all-perovskite tandem solar cells. PEDOT:PSS-based devices show the best power conversion efficiency of 14% in SJ and 17.2% in all-perovskite tandem architecture. By using photoluminescence and ultraviolet photoelectron spectroscopy, we show that this behavior is due to better energy alignment at the PEDOT:PSS/PK than the SAM/PK interface. However, SAMs also show lower nonradiative recombination rates at this interface. The results identify the limits of the effectiveness of 2PACz and MPA in mixed lead–tin MA-free perovskite solar cells and confirm the need for other SAMs with improved energy-level alignment while maintaining their passivating properties.

For the first time, we investigate the preparation of Ag/Bi halide double salts with the formula Ag_aBi_bI_a+3b by single source thermal ablation (SSTA), using different precursor stoichiometries (2.0 ≥ Ag/Bi ≥ 0.5). Silver bismuth iodides are interesting because they combine outstanding stability under ambient conditions with low toxicity and large light absorption coefficients. Thanks to their optical band gaps in the 1.4–2.0 eV range, they have been proposed for different applications, such as indoor photovoltaics and top cell in Si- and CIGS-based tandem solar cells. Independently of the precursor composition, films obtained by SSTA are all characterized by a dominant phase that is closely related to that of Ag₂BiI₅. We demonstrate that the Ag₂BiI₅ and BiI₃ rhombohedral phases coexist in the films prepared from precursors with Ag/Bi ≤ 1 even though no evidence of BiI₃ is achieved by XRD powder diffractometry in the θ–2θ Bragg–Brentano geometry or by UV–vis absorption measurements. The presence of the BiI₃ phase worsens the performance of planar solar cells, so the Ag/Bi = 2.0 precursor provides the best solar cells. Remarkably, these devices show a power conversion efficiency of 1.02%, an open-circuit voltage (V_OC) of 0.71 V, and a short-circuit current density (J_SC) of 3.09 mA/cm², which are comparable to those reported in the literature for planar solar cells, despite the lack of any device optimization. The reported results confirm that SSTA can be successfully used for the exploitation of silver bismuth iodides in photovoltaic applications.

The growing need for energy conversion technologies has stimulated the development of innovative electrocatalysts designed explicitly for oxygen evolution reactions (OER). Nonprecious metal/carbon-based composites are widely studied for this purpose due to their low cost and unique structures. However, conventional methods for preparing transition metal/carbon composites are often cumbersome and time-consuming. These methods have other disadvantages, such as poor catalyst uniformity, limited potential for surface modification, and excessive oxidation of metal particles. In this work, we employed a simple one-step molten salt (MS) method to synthesize FeNi alloy/carbon composites. The sample prepared by the MS strategy, with an optimal Fe/Ni ratio, performs a low overpotential of 279.4 mV at a current density of 10 mA cm^–2 and a small Tafel slope of 45.7 mV dec^–1. Compared with the sample prepared through traditional pyrolysis, the sample prepared by the MS method demonstrates modulated and optimized surface characteristics for both the carbon support and metallic particles. Furthermore, the synthetic process enables the uniform growth of alloy particles on the carbon substrate. These structural improvements result in abundant defects and active sites, significantly enhancing OER activity. Overall, this work highlights the role of the MS method in promoting the catalytic activity of FeNi alloy/carbon composites. This research contributes to advancing non-noble metal electrocatalysts for future catalytic applications.

Indoor photovoltaics represent a sustainable and reliable source of energy in low-power electronic devices, including the rapidly increasing Internet of Things (IoTs). In this context, hybrid perovskites have garnered surging attention as potential photovoltaic materials owing to their exceptional optoelectronic properties, appropriate band gaps, and ease of solution-based fabrication. Unfortunately, the high cost and necessity of hygroscopic dopants for hole-transporting materials (HTMs) such as spiro-OMeTAD is a major bottleneck, hindering the large-scale application of perovskite solar cells (PSCs). Considering the benefits of electron-deficient units in boosting the efficiency and stability of photovoltaic dyes and polymers, herein, we introduce two donor–acceptor–donor (D–A–D) quinoxaline-based HTMs, YN1 and YN2. These materials incorporate a D–A–D structure to strategically modulate HOMO levels, enhance stability, and reduce production costs. Differences in their photovoltaic performances were studied by using photoluminescence quenching, hole reorganization energy, hole mobility, and charge extraction capability. Dopant-free YN2-based PSCs deliver a maximum power conversion efficiency (PCE) of 28.35% at indoor photovoltaics (1000 lx LED illumination, 0.321 mW cm^–2) and 15.62% at outdoor conditions (AM 1.5G illumination, 100 mW cm^–2) which are at par with the gold-standard, doped spiro-OMeTAD. Compared to that, YN1-based devices show moderate efficiencies of 23.23% in indoor conditions and 10.92% in outdoor conditions. Interestingly, the YN2-based device outperforms YN1 and spiro-OMeTAD-based devices in long-term operational stability by maintaining 41.3% of initial PCE after 550 h of thermal stress at 85 °C with RH ∼ 55%. Alongside, due to the facile two-step synthesis process, the price of YN2 is only $35/g, which is cost-effective compared to commercially available high-performance reference HTMs. The economic viability, outstanding photovoltaic efficiency, and long-term stability of YN2 indicate its strong potential for future practical applications.

Hitherto, research into alkaline exchange membrane fuel cells lacked a commercial benchmark anionomer and membrane, analogous to Nafion in proton-exchange membrane fuel cells. Three commercial alkaline exchange ionomers (AEIs) have been scrutinized for that role in combination with a commercial platinum-group-metal-free Fe–N–C (Pajarito Powder) catalyst for the cathode. The initial rotating disc electrode benchmarking of the Fe–N–C catalyst’s oxygen reduction reaction activity using Nafion in an alkaline electrolyte seems to neglect the restricted oxygen diffusion in the AEIs and is recommended to be complemented by measurements with the same AEI as used in the alkaline exchange membrane fuel cell (AEMFC) testing. Evaluation of the catalyst layer in a gas-diffusion electrode setup offers a way to assess the performance in realistic operating conditions, without the additional complications of device-level water management. Blending of a porous Fe–N–C catalyst with different types of AEI yields catalyst layers with different pore size distributions. The catalyst layer with Piperion retains the highest proportion of the original BET surface area of the Fe–N–C catalyst. The water adsorption capacity is also influenced by the AEI, with Fumion FAA-3 and Piperion having equally high capabilities surpassing Sustainion. Finally, the choice of the membrane influences the ORR performance as well; particularly, the low hydroxide conductivity of Fumion FAA-3 in the room temperature experiments mitigates the ORR performance irrespective of the AEI in the catalyst layer. The best overall performance at high current densities is shown by the Piperion anion exchange ionomer matched with Sustainion X37–50 membrane.

Understanding the difference between the activities of catalysts in OER and ORR is crucial for designing a bifunctional catalyst for rechargeable fuel cells and metal–air batteries, which so far remains elusive. In this work, a wide range of 3d transition metal-based perovskite oxide catalysts were considered to uncover the difference in the trends between OER and ORR. By performing systematic symbolic regression on experimental data, we confirmed the previous descriptor (d_B, n_B) for OER activity and identified a new descriptor (−d_B, –|e_g – 0.8|) for ORR activity, where d_B, n_B, and e_g are the number of d-electrons, oxidation state, and e_g orbital occupancy of the transition-metal cation, respectively. To understand the descriptors, first-principles calculations based on multiple reaction mechanisms were performed. Results show that the dependence of activity on the B-site metal species of the ABO₃ perovskites exhibits a volcano-shaped relation in both OER and ORR. We found that the experimental activity descriptors can be explained by the computed results from multiple mechanisms (4e^– transfer). The difference between the experimental OER and ORR activity descriptors originates from that the volcano top of the OER performance against the 3d transition metal is located near the end of this period and that of the ORR is in the middle. For ORR, further calculations show that the 2e^– pathway was only important on Ni and Cu oxides on which the binding of *OOH is weak. These descriptors and insights can be helpful in guiding the design of perovskite catalysts for OER and ORR.

Battery safety plays a critical role in ensuring the reliable operation of lithium-ion batteries during the service lifetime. Lithium-ion batteries often remain in a static state for extended periods during vehicle applications, particularly in high-temperature conditions, which poses significant challenges to their safety performance. In this content, this work investigates the evolution of overcharge performances and underlying mechanism during high-temperature calendar aging. The findings reveal that overcharge tolerance, represented by thermal runaway triggering temperature and duration time, decreases with aging. Simultaneously, thermal hazards, indicated by maximum temperature and maximum temperature rise rate, also diminish with aging. Multidimensional characterization demonstrates that lithium plating, gas generation, and transition metal dissolution are key failure mechanisms leading to performance degradation. Specifically, the reduced thermal stability of the anode and cathode is identified as the primary cause of the decline in overcharge tolerance. In contrast, the loss of active materials and active lithium emerges as the major factor contributing to the reduction in thermal hazard with aging.

Transition metal dichalcogenides, particularly Nb-doped MoS₂, present unique electronic and thermoelectric properties that make them promising candidates for a variety of applications, including photovoltaic cells and thermoelectric devices. Here, we investigate the influence of controlled substitutional doping on the electrical conductivity and thermoelectric performance of MoS₂ as a function of crystal thickness. We report an exceptional bulk conductivity of up to 360 ± 30 S cm^–1 and a peak power factor of 370 ± 80 μW m^–1 K^–2 at room temperature. Our findings reveal that the interplay between doping concentration and thickness can decouple the Seebeck coefficient from electrical conductivity, overcoming the typical trade-off observed in conventional materials. This research highlights the role of surface effects and depletion regions in p-type transition metal dichalcogenides, providing a pathway for developing efficient bipolar thermoelectric devices. The stability and tunability of p-type doping in MoS₂ also suggest potential applications in microscale cooling, thermal sensors, and photovoltaic systems.

Large-size grains play a crucial role in enhancing the properties of ferroelectric films and improving device performance. In this work, hydroiodic acid is used as an additive to promote the crystallization of a narrow-band gap molecular ferroelectric film (hexane-1,6-diammonium pentadiammonium). The complex-regulated processes resulted in a significant increase in grain size from 0.2 to 6.4 μm (32-fold enhancement), accompanied by a reduction in band gap, optimization of the energy level structure, and enhancement of ferroelectric properties. The optimized film exhibited nearly a 10-fold improvement in the performance of ferroelectric photovoltaic devices, which is further enhanced after polarization. This study introduces complex regulation strategies for optimizing molecular ferroelectrics, offering valuable insights for future research on molecular ferroelectrics.

Calcium–metal batteries with polymer electrolytes are emerging as promising next-generation energy systems owing to their high energy density, natural abundance of Ca in the Earth’s crust, and inherent safety. However, developing suitable polymer electrolytes for Ca-metal batteries remains challenging owing to compatibility issues with Ca-metal anodes and high-voltage cathodes. Herein, we report a dual-cation (Ca²⁺/Li⁺) gel polymer electrolyte (GPE), designed using calcium monocarborane (Ca(CB₁₁H₁₂)₂) and adjusting the lithium borohydride (LiBH₄) concentration, which enhanced oxidation stability while maintaining compatibility with Ca metal. The incorporation of the CB₁₁H₁₂^– anion improved the oxidation stability of the electrolyte, increasing the oxidation potential from 2.2 to 2.6 V (vs Ca²⁺/Ca). Cyclic voltammetry and galvanostatic tests demonstrated reversible plating/stripping properties and high stability against Ca-metal anodes. The reversible operation of the Ca-metal battery was confirmed using a titanium disulfide (TiS₂) cathode, which achieved an initial discharge capacity of 188.5 mA h g^–1. Exsitu X-ray diffraction analysis corroborated this finding by revealing crystallographic changes in TiS₂. This Ca-GPE, with its enhanced oxidation stability, paves the way for developing high-voltage Ca metal–polymer batteries.

Transparent photovoltaic devices (TPVDs) with on-site power generation capabilities present a sustainable solution for urban energy needs and integrated applications. Silver nanowires (AgNWs) show great promise as transparent conducting electrodes in TPVDs due to their high conductivity, transparency, and environmentally friendly synthesis. Achieving high-performance optoelectronic devices requires careful optimization of material densities to balance light–matter interactions, which can be controlled by adjusting the density of AgNWs. This study examines the relationship between the AgNW density and key performance metrics of TPVDs featuring a pyroelectric-ZnO absorber. ZnO/NiO heterojunctions were fabricated via sputtering with varying densities of AgNWs applied as the top electrode. Among the densities tested, TPVDs with 35% AgNW coverage demonstrated the best on-site power performance, achieving a power conversion efficiency of 3.431% and an open-circuit voltage of 305 mV. Additionally, the study explored the effect of AgNW coverage on photodetection properties across the UV to the visible range. The optimized TPVD generated a pyrocurrent-assisted photocurrent of approximately 429 μA under modulated optical illumination, highlighting the impact of the top electrode design on photoelectric performance. This study offers a method for optimizing conducting nanowire density to design high-performance transparent optoelectronics with on-site energy generation.

Aliovalent cation doping into a heterogeneous photocatalyst affects several of its physicochemical properties, including its morphological characteristics, optical absorption behavior, and charge carrier dynamics, causing a drastic change in its photocatalytic activity. In the present work, we investigated the effects of aliovalent cation doping on the visible-light H₂-evolution photocatalytic activity of the Ruddlesden–Popper layered perovskite oxynitride K₂LaTa₂O₆N. The photocatalytic activity toward H₂ evolution from an aqueous NaI solution was found to be enhanced by an increase in the specific surface area of the K₂LaTa₂O₆N photocatalyst, which could be realized upon doping with lower-valence cations (e.g., Mg²⁺, Al³⁺, and Ga³⁺). Among the dopants examined at 1 mol % doping, Ga resulted in the highest activity. The activity of the Ga-doped specimen was further improved with increasing Ga concentration, where the maximal activity was obtained at 10 mol %, corresponding to an apparent quantum yield of 2.7 ± 0.4% at 420 nm from aqueous methanol. This number is the highest reported for a layered oxynitride photocatalyst. In the Ga-doped K₂LaTa₂O₆N, a trade-off was observed between the Ga concentration and the photocatalytic activity. Although doping with Ga reduced the particle size of K₂LaTa₂O₆N and suppressed undesirable charge recombination, it led to an enlarged bandgap, unsuitable for visible-light absorption.

Conversion-type materials are promising cathodes with high theoretical capacities for rechargeable aluminum batteries (RABs). However, the cathodes are mainly based on a solid-to-solid conversion chemistry with sluggish reaction kinetics, resulting in a large volume change and severe electrode pulverization during cycling. Herein, a solution-to-solid conversion chemistry which resolves the cycling problems is found in carbon-supported In₂O₃ (In₂O₃@C) cathode, which exhibits fast-charging rate capability and excellent cycling stability in RABs. The In₂O₃@C architecture is featured with rod-shaped hollow carbon decorated with ultrafine In₂O₃ nanoparticles. The solid In₂O₃ converse into soluble InCl (In⁺) in the first discharge. In the following cycles, a reversible solution-to-solid conversion reaction occurs between soluble InCl (In⁺) and sparingly soluble InCl₃. The highly conductive carbon skeleton provides sufficient reaction sites to guarantee the reversible precipitation of solid InCl₃ as a charge product. Meanwhile, due to fast oxidation kinetics and the self-healing property of the solution phase, the Al|In₂O₃@C cell exhibits a high capacity of 335 mA h g^–1 with marginal cell overpotential of just 50 mV at 0.2 A g^–1, superior charging rate capability, and outstanding cycling stability at 5 A g^–1. This work provides insights into the development of cathode materials with a solution-to-solid reaction mechanism for high-performance RABs.

Cu–S-based multicomponent compounds with sphalerite-like frameworks have garnered attention as midtemperature p-type thermoelectric (TE) materials. Their valence bands, primarily comprising Cu–S hybridized orbitals, control electronic properties. Herein, for colusites Cu₂₆Tr₂M₆S₃₂ (Tr = V, Nb, and Ta; M = Ge and Sn), we investigate the distinctive interaction between the Cu–S-based sphalerite-like framework and Tr at the interstitial tetrahedral sites to improve the Seebeck coefficient (S). According to ab initio calculations, the d(t₂) and d(e) orbitals of Tr interact with the valence band maxima at the Γ and M points, respectively. The hybridization between the Tr-t₂ and S orbitals (under the presence of Tr), along with structural modifications, reduces the energy of the Γ band maximum toward the Fermi level, thereby increasing S. This understanding is expected to be a foundation for further advancements in the TE properties of Cu–S-based compounds.

In an attempt to obtain fully functional cathode materials for zero-gap alkaline water electrolysis, Ni foam substrates with various pore diameters were modified through galvanostatic electrodeposition of Ni–Sn alloys as an easily scalable procedure. To optimize the production process for each substrate, Ni–Sn alloys were electrodeposited at five different constant current densities. The obtained cathodes were primarily subjected to hydrogen evolution in 1 M KOH to evaluate their activity, while the best-performing samples were further investigated in 30 wt % KOH at 70 °C in a three- and two-electrode arrangement. Detailed electrochemical impedance spectroscopy analysis of hydrogen evolution reaction (HER) conducted with a three electrode arrangement indicated two semicircles on the Nyquist plots that confirmed that the adsorption of intermediate (H_ads) is potential dependent. Relevant HER parameters such as exchange current density and relaxation time showed exceptional performance of optimized electrodes. During zero-gap single cell tests with bare Ni foam used as the anode, onset voltages for Ni–Sn cathodes were around 1.64 V (for bare foams, 1.99 V), with cell voltage at 1 A cm^–2 being as low as 2.03 V (for bare foams, 2.57 V). The cathodes were also subjected to a long-term stability test, showing excellent activity preservation. Great stability, low cell voltage, and low production cost confirm their suitability for industrial applications. Top-view as well as cross-section electron microscopy analysis have shown that the entire foam surface was evenly covered with Ni–Sn coating. The composition of the investigated coatings was within the range of Ni_(1+x)Sn (0 < x < 0.5) metastable phase and practically independent of deposition current density. Aberration-corrected scanning transmission electron microscopy revealed that the so-called metastable phase is in fact the Ni₃Sn₂ phase, which is shown for the first time for electrodeposited Ni–Sn alloys.

Li₃VO₄ (LVO) presents significant advantages in cost and capacity, making it a promising candidate for next-generation lithium-ion battery (LIB) anodes. However, its low electronic conductivity hampers practical applications. Herein, we report a Sm-modified Li₃VO₄/C composite (LSVO/C) designed for high-performance LIBs. Sm doping introduces additional defects and optimizes the electronic structure of Li₃VO₄, resulting in a significantly enhanced electronic conductivity (2.94 × 10^–3 S cm^–1) of the composites. Furthermore, the carbon-fiber-based framework effectively maintains structural stability during cycling, facilitating superior ion transport kinetics. Benefiting from these enhancements, the LSVO/C composite achieves remarkable discharge capacities of 379.5 mAh g^–1 at 0.25 C and 260.1 mAh g^–1 at 12.5 C. Additionally, an LSVO/C||NCM111 full cell, using LiNi_1/3Co_1/3Mn_1/3O₂ (NCM111) as the cathode, retains a discharge capacity of 50.5 mAh g^–1 after 1000 cycles at 3.0 C, highlighting the potential of LSVO/C for practical applications. This unique method in preparing anode material will open new gates for highly efficient LIBs.

Polysulfide-based aqueous redox flow batteries (PS-ARFBs) are a viable alternative for energy storage owing to their impressive theoretical capacity, inherent safety features, low operating costs, and cost-effective design. However, the primary challenges facing PS-ARFBs are slow kinetics and limited cycle life, which significantly impede their practical applications. To overcome these obstacles, we have developed an innovative functional electrode (KB/S-HCN-2:1-CF) that integrates S₈/S_x^2– redox pairs (KB/S) with hydrophilic carbon nanocuboids (HCNs) as electrocatalysts. This design enhances the redox kinetics of polysulfides and optimizes sulfur utilization. Remarkably, the KB/S-HCN-2:1-CF electrode reduces the overpotential of a polysulfide-ferri/ferrocyanide (S–Fe) redox flow battery from 1110 to 237 mV at a current density of 40 mA cm^–2. Furthermore, an S–Fe flow cell equipped with this modified electrode demonstrates an increased initial capacity of 268.9 mAh at 40 mA cm^–2 at a lower S_x^2– concentration and an improved energy efficiency of nearly 10%. Particularly, a plausible explanation for the roles of S₈ and HCNs in promoting the reduction of polysulfides has been proposed, as confirmed by DFT methods and ex-situ UV–vis spectroscopy in polysulfide electrolytes. This study offers a promising approach to the challenges faced by PS-ARFBs, paving the way for high-capacity and long-lasting performance.

Achieving all-solid-state batteries requires the development of solid electrolytes with high ionic conductivities, high Li-ion transference numbers, and wide-range electrochemical stabilities. Molecular crystals, which combine a moderate flexibility similar to that of polymer electrolytes with ion conduction paths resembling those of ceramic electrolytes, have attracted attention as promising candidates for innovative solid electrolytes. Improving the properties of molecular crystalline electrolytes requires clarifying the correlations between their hierarchical structures and electrolyte properties, as well as establishing material design guidelines. Herein, we report the organic molecular crystal Li₂{N(SO₂CF₃)}₂(NCCH₂CH₂CN)₃, hereafter referred to as Li₂(TFSA)₂(SN)₃, as a promising solid electrolyte. This molecular crystal exhibits an ionic conductivity of 3.6 × 10^–5 S cm^–1 at 30 °C with a considerably high Li-ion transference number of 0.98. In addition, we confirmed the wide electrochemical stability of the 5 V-class cathodes and their compatibility with Li metal anodes. Scanning electron microscopy observations revealed the formation of tightly contacted grain boundaries in the powder-molded pellets of Li₂(TFSA)₂(SN)₃. Notably, the previously reported molecular crystalline electrolyte Li(PF₆)(NC(CH₂)₄CN)₂ (Li(PF₆)(ADN)₂) formed an interface containing liquid components of substantial thickness with a Li-ion transference number of only 0.54. These results highlight that both, the selection of constituent molecules and anions and the design of the grain boundary interface, play crucial roles in achieving superior electrochemical stability and selective Li-ion conductivity in the development of molecular crystalline electrolytes.

This study aims to enhance the electrochemical performance of supercapacitors by maximizing the specific surface area and surface treatment of carbon-material electrodes through fluorination doping. Polyacrylonitrile (PAN)-based carbon fibers (PCFs) were produced via electrospinning and subsequently activated with potassium hydroxide (KOH) at 800 °C to obtain activated PAN-based carbon fibers (APCFs). Direct fluorination was then used to synthesize fluorinated PAN-based carbon fibers (FPCFs). The specific surface area of the electrode materials was maximized by adjusting the concentration of the electrospinning solution. The effect of fluorination on changes in surface elemental content was precisely managed to mitigate the decrease in porosity. The pore size distribution, vital for determining the specific capacitance of supercapacitors, was thoroughly assessed. After the activation and fluorination processes, the specific surface area of the FPCFs increased significantly to 1753.2 m² g^–1. This value is notably higher than that of commercial activated carbons, which typically range from 1200 to 1500 m² g^–1. The supercapacitor properties of the resulting materials were evaluated, revealing a specific capacitance of 176.2 F g^–1 for FPCF with an electrospun PAN concentration of 7 wt %.

Efficient photoanodes for visible-light-driven water oxidation are eagerly desired to construct practical water splitting systems to produce O₂ and H₂ using solar energy, which is one of the most prospective approaches for sustainable H₂ production. To further improve photoelectrochemical (PEC) water oxidation by a unique nitrogen-doped CuWO₄ (N-CuWO₄) photoanode, a Fe-co-deposited SnO_x (Fe-SnO_x) layer was formed on the photoanode surface by photoassisted electrodeposition. The incident photon-to-current conversion efficiency (IPCE) of the N-CuWO₄ photoanode was improved by 1.9 times at 1.23 V vs a reverse hydrogen electrode (RHE) by the Fe-SnO_x layer, which is contributed by the increased catalytic efficiency (η_cat) from 41.7 to 67.0%. Photoelectrochemical impedance spectroscopy (PEIS) measurement showed that the rate constant (k_O2) of water oxidation at the surface increased from 5.5 to 10.2 s^–1 and the rate constant (k_rec) of surface recombination of photogenerated carriers decreased a little from 8.9 to 8.6 s^–1 by the Fe-SnO_x layer. This indicates a bifunctional role of the Fe-SnO_x catalyst layer in promoting the water oxidation reaction at the surface and suppressing the surface recombination of photogenerated carriers. For comparison with the case of a SnO_x layer (no Fe-co-deposition), the k_O2 value (6.7 s^–1) of SnO_x/N-CuWO₄ electrodes was lower than that (10.2 s^–1) for the Fe-SnO_x/N-CuWO₄ electrode but higher than that (5.5 s^–1) for bare N-CuWO₄. Both SnO_x and Fe-SnO_x layers on the N-CuWO₄ surface improved k_O2; however, the mechanism of improved k_O2 is distinct between these layers: passivation effect of the SnO_x layer to prevent electron tunneling at the interface of the N-CuWO₄ surface/electrolyte and promotion effect of the Fe-SnO_x layer on water oxidation at the surface. The k_rec value (6.9 s^–1) for the SnO_x/N-CuWO₄ electrode was 1.3 times lower than that (8.9 s^–1) of the bare N-CuWO₄ electrode, which clearly shows the effect of the passivating SnO_x layer on the suppression of the surface recombination of photogenerated carriers.

Sodium storage mechanisms and microstructures play a key role in improving the sodium storage capacity of hard carbon (HC) anodes; however, the storage mechanisms of sodium ions in coal-carbon-derived HC and the effective regulation of microstructures at the molecular level are still scarce. In this work, it is proposed for the first time that the coaling effect affects the microstructure and the Na⁺ diffusion coefficient in coal-derived HCs during their discharge by grafting aryl rings and oxygen-containing functional groups within and between the main chains of the precursors. We propose and confirm two Na⁺ storage mechanisms that are closely related to the coalisation effect. Aromatic rings and oxygen-containing functional groups induce Na⁺ aggregation during Na⁺ diffusion, leading to the formation of metal clusters in low-voltage regions. Therefore, the effects of aromatic rings and oxygen-containing functional groups on the local microstructure of HCs should be considered when designing HCs. In this work, HCs with specific graphite microcrystalline structures were prepared by screening coal precursors, and constraints between graphite microcrystalline parameters and precursors were revealed. This work provides theoretical guidance to study the storage mechanism of Na⁺ through the coalisation effect and offers new ideas for the development of high-performance coal-derived anodes for sodium-ion batteries.

The atomic scale relaxation dynamics of eutectic F⁷LiNaK (46.5 LiF–11.5 NaF–42 KF mol %, Li-7 enriched) were measured using quasi-elastic neutron scattering (QENS) over a temperature range of 500–750 °C. The effect of adding 0.988 mol % cerium, 0.499 mol % cesium, and 1.21 mol % zirconium individually to the dynamics of F⁷LiNaK was also investigated. The relaxation process in both pure and doped F⁷LiNaK molten salts was fit with a stretched exponential function and the temperature dependence follows an Arrhenius behavior over a wavevector transfer range of 0.4 Å^–1 < Q < 0.9 Å^–1. The measured activation energy for self-diffusion is E_a = 0.77 ± 0.02 eV/atom for pure molten F⁷LiNaK. The QENS response with additives added to F⁷LiNaK was also fit with a stretched exponential and the associated Arrhenius behavior was characterized with activation energies of E_a = 0.88 ± 0.01 eV/atom for zirconium (1.21 mol %), E_a = 1.02 ± 0.02 eV/atom for cerium (0.988 mol %), and E_a = 0.71 ± 0.03 eV/atom for cesium (0.499 mol %). The measured diffusivities are compared to those simulated with a neural network force field model by Lee et al. [Lee, S.-C. Comparative Studies of the Structural and Transport Properties of Molten Salt FLiNaK Using the Machine-Learned Neural Network and Reparametrized Classical Forcefields. J. Phys. Chem. B 2021, 125(37), 10562–10570].

Composite phase change materials (CPCMs) have promising applications as passive cooling technologies in the energy sector. However, the low thermal conductivity and obvious leakage defects of CPCMs limit their large-scale development. Herein, a highly thermally conductive CPCM with polyethylene glycol (PEG), metal–organic gel (MOG), and carbon microspheres (CMS) (PMEC) has been proposed and prepared via a hydrothermal method with noncovalent bonding of metal ions and organic acids. The scanning electron microscopy (SEM) and thermal conductivity of different PMECs indicate that the thermal conductivity of PMEC2 is significantly anisotropic, with 3.79 W·m^–1·K^–1 when the CMS content is 5 wt %. Besides, the experimental results indicate that PMEC2 can reach a latent heat value of 118 J/g, exhibiting excellent durability after 20 heating and cooling cycles. Additionally, a PMEC2-based battery module incorporating CMS and PEG with epoxy resin (ER) as the supporting skeleton has been assembled for battery modules. The charge and discharge tests are performed on the battery modules at different discharge rates. PMEC2 can control the temperature and temperature difference within 63.03 and 5.01 °C, respectively, which will control the temperature of the battery module and balance the temperature distribution uniformly. This indicates that the designed CPCM can provide an effective approach to explore high thermal conductivity composite materials for thermal management and other energy storage fields.

Recently, the rapid advancement of electric vehicles has resulted in a growing demand for enhanced battery performance, particularly in application scenarios that necessitate fast (dis)charging properties and ultralong cycle life. The capacitor lithium-ion batteries, which fully leverage the synergistic advantages of a double electric layer and redox reaction storage mechanisms of lithium-ion batteries to optimize both energy and power properties, are poised to play a significant role to meet these requirements. Herein, this paper designs a difunctional electrolyte and investigates its effects on the electrochemical behaviors within a capacitor lithium-ion battery. The objective of this study is to develop functional electrolytes for capacitor lithium-ion batteries tailored for carbon-rich systems with dual energy storage mechanisms. The capacitor lithium-ion battery comprising LiNi_0.6Co_0.2Mn_0.2O₂-activated carbon (cathode)||hard carbon (anode) demonstrates attractive performance, while utilizing a difunctional electrolyte system of LiPF₆ and tetraethylammonium tetrafluoroborate. With the additives of vinylidene carbonate and fluorinated ethylene carbonate, the batteries exhibit commendable reversible capacities of 111.5 and 116 mAh/g at 180 mA/g, respectively, with capacity retention rate exceeding 90% after 100 cycles. Consequently, this research provides both theoretical and technical support for the advancement of capacitor lithium-ion batteries characterized by a wide operating temperature range, extended lifespan, and enhanced safety.

Efficient oxygen evolution reaction (OER) electrocatalysts are crucial for various electrochemical processes, including water splitting. In this study, we investigated the effect of cobalt substitution on the OER activity of nickel orthophosphate by employing a straightforward coprecipitation synthesis route. A series of Ni/Co orthophosphate catalysts, Ni_3–xCo_x(PO₄)₂·8H₂O (x = 0, 1, 1.5, 2, and 3), were prepared. Among them, NC15 (Ni/Co = 1.5) exhibited the lowest overpotential of 321 mV for achieving 10 mA/cm² and a turnover frequency (TOF) of 605.9 s^–1 at 600 mV vs RHE, with a Tafel slope of 100.15 mV dec^–1. This enhanced performance can be attributed to the synergistic interplay of the highest TOF; disorder in the cobalt and nickel cations in the crystallographic sites within the crystal structure; and, importantly, a cathodic shift in the Ni oxidation peaks observed in the Co-containing catalysts. Here, we report the novel observation of an inductive effect of cobalt within the nickel phosphate structure, which influences the Ni redox behavior and contributes significantly to improved OER activity. XPS analysis revealed shifts in the binding energies of Co 2p, O 1s, P 2p, and Ni 2p, indicating a change in the electronic structure of the elements. DFT calculations suggest that Co substitution leads to band gap narrowing and charge redistribution, with excess charge accumulating at the Co site and transferring to the neighboring oxygen atoms.

Calcium metal batteries (CMBs) are promising candidates for next-generation electrochemical energy storage systems due to their high volumetric capacity, abundance, sustainability, and safety. Recent DFT predictions suggested that the layered CaCoSO phase can enable sequential Co²⁺/Co³⁺ and Co³⁺/Co⁴⁺ redox activity at an average potential of 2.8 V vs Ca²⁺/Ca, making it a promising candidate for high-energy-density CMBs [Torres, A. Chem. Mater. 2021, 33(7), 2488–2497]. Inspired by these metrics, in this work, we present the synthesis and electrochemical analysis of the CaCoSO phase. Theoretical capacity can be extracted through galvanostatic cycling, albeit accompanied by high polarization. In situ XRD and DEMS analyses, however, reveal that the capacity arises primarily from a combination of material decomposition and electrolyte degradation rather than reversible Ca²⁺ ion storage. The apparent discharge capacity is attributed to the cathodic decomposition of generated water during the subsequent anodic step, making the overall electrochemical process appear as reversible. This work underscores the complexity of achieving stable calcium-ion storage and aligns with similar challenges reported for other systems, highlighting the need for realistic testing conditions and providing critical insights to guide the development of advanced electrode materials and electrolytes for CMBs.

Two-dimensional (2D) structures hold promise as advanced lithium-ion battery (LIB) anode materials. Recently synthesized 2D graphullerene faces challenges due to its large electronic insulating band gap. In this study, we construct a quasi-tetragonal graphullerene, C₃₆, denoted as GrF-C₃₆, using C₃₆ fullerenes with D_6h symmetry as the structural unit. First-principles calculations revealed that the delocalized p_z orbitals lead to metallicity, combined with intrinsic porosity, resulting in a large theoretical capacity of 496 mAh/g when they are used as LIB anode material. However, the structure exhibits a large migration barrier for lithium ions (Li⁺), limiting its rate performance. To address this, we further adopt the strategy for constructing long-range-ordered carbon by “removing” the [2 + 2] cycloaddition bonds to form intrinsic one-dimensional channels in the structure, denoted as LOPC-C₃₂. Calculations showed that LOPC-C₃₂ maintains metallicity and enhances the structural stability while achieving a Li capacity of 906 mAh/g. The migration barrier for Li⁺ within these channels is only 0.12 eV, significantly improving the rate performance. Coupled with an average open-circuit voltage of 0.43 V and a structural deformation of only 5% at a maximum Li capacity, LOPC-C₃₂ emerges as an excellent anode material. Our work provides a design strategy for the application of graphullerenes in LIBs.

Solar-driven water splitting for hydrogen production is a promising solution to the energy crisis. Reducing the recombination of photogenerated charge carriers is a key strategy for enhancing the hydrogen evolution performance. In this study, a type-II heterojunction catalyst, CdS/Co₃O₄, was successfully prepared using a self-assembly method. The tight coupling between CdS and Co₃O₄ facilitates efficient electron transfer. The heterojunction promotes the separation of photogenerated electrons, thereby reducing the charge carrier recombination. Additionally, the quantum confinement effect of Co₃O₄ shortens the electron migration distance. Under illumination with a 10 W white light source, the hydrogen evolution rate of CdS/Co₃O₄ reached 21.07 mmol g^–1 h^–1, approximately three times that of pure CdS. Electron paramagnetic resonance and density functional theory calculations were employed to elucidate the electron transfer mechanism during the photocatalytic process. This study provides a theoretical foundation for the design and mechanistic investigation of quantum-dot-based heterojunction photocatalysts.

Lowering the thermal conductivity by phonon scattering has been previously studied in high-entropy alloys (HEAs). This concept has been extended to half-Heusler (HH) alloys in the form of entropy engineering by substituting one of the elements with multiple elements or by combining 2 HH alloys to form a double half-Heusler alloy. Here, entropy engineering of double HH Ti₂NiCoSn_0.5Sb_1.5 by the substitution of Ti with Al, Ta, and Zr was studied. Due to their low solubility in Ti, Al and Ta formed Ni-based intermetallic phases. Compositional tuning was performed based on the optimum individual dopant levels of Al, Ta, and Zr. Compositional tuning revealed that the introduction of Ta and Al improved the power factor and lowered thermal conductivity due to the formation of the TaNiCoAl quaternary full Heusler (FH) secondary phase. Zr was completely soluble in the HH alloy, lowering the thermal conductivity at the expense of the power factor. Ti_1.6Ta_0.2Al_0.2NiCoSn_0.5Sb_1.5 with a power factor of 3.83 mW/mK² had a ZT of 0.71 at 823 K, which is higher than those of other double HH alloys. Ti_0.6Ta_0.2Al_0.2ZrNiCoSn_0.5Sb_1.5 also exhibited a low lattice thermal conductivity of 2.19 W/mK at 420 K, which is comparable to that of Hf-substituted HH alloys. On the other hand, entropy engineering by equimolar substitution of elements did not lead to improvement in properties, underlining the need for compositional tuning in the HH alloys.

Mesoporous carbons, as the catalyst support in proton exchange membrane fuel cells (PEMFCs), can improve the specific activity of catalysts and the high-power performance of cells, but the underlying physics remains elusive. In this work, a model is proposed to describe the oxygen transport process for both exterior and interior platinum (Pt) catalysts on the mesoporous carbon catalyst layers (CLs) under various relative humidity (RH) conditions, considering the structure evolution of interior pores induced by the condensed water. We find that although the local oxygen transport resistance (R_Pt^O₂) of interior Pt catalysts is less than that of exterior Pt catalysts, too much Pt deposit in the interior pores would still lead to the remarkable increase of R_Pt^O₂. The output performance of mesoporous carbon CLs is better than that of solid carbon CLs at a high RH but is instead worse at a low RH value. A data-driven model is then built to unravel the structure–performance relation of the mesoporous carbon. By reducing R_Pt^O₂ via microstructure optimization, we determine an optimal pore size of mesoporous carbons where the output performance is the best within the studied range of RH values.

The development of efficient and durable hydrogen evolution reaction (HER) electrocatalysts is critical for sustainable energy conversion. Although platinum (Pt) serves as a benchmark HER catalyst, its practical application is hindered by the high cost, limited durability, and susceptibility to CO poisoning. In this work, we report a heterojunction Pt-based catalyst, Pt@NCL-MXene, synthesized by LiF etching of MXene and subsequent NH₃ calcination. This process introduces dual nitrogen (N) and fluorine (F) doping and yields a nitrogen-doped carbon layer (NCL) coating on Pt nanoparticles with an average size of only 3.4 nm. Compared with conventional Pt–C catalysts, Pt@NCL-MXene exhibits a larger specific surface area, enhanced electron transfer efficiency, and an optimized d-band center, thereby facilitating both H* adsorption and desorption. As a result, Pt@NCL-MXene achieves a significantly lower overpotential of 73 mV at a current density of 100 mA cm^–2, alongside improved kinetics and stability under operational conditions. Furthermore, the 9 wt % F-rich MXene support effectively suppresses CO adsorption on Pt, reducing the CO uptake to 0.224 mmol g^–1, which is purportedly lower than that of Pt–C (0.264 mmol g^–1), thereby mitigating CO poisoning and prolonging the catalyst’s service life. These findings offer insights into the rational design of advanced CO-resistant Pt-based HER electrocatalysts.

The formation of Li₆PS₅Cl argyrodite solid electrolyte pellets typically involves compaction at ∼20 °C and hundreds of megapascal of pressure, and the resulting pellets usually need >10 MPa operating pressure to achieve ionic conductivities >1 mS cm^–1 at 25 °C and/or sputtered metal electrodes. This work demonstrates a key advance achieved with pellet fabrication at 150 °C and 300 MPa with foil electrodes: >2 mS cm^–1 ionic conductivity at 20 °C with <1 MPa operating pressure. Scanning electron microscopy reveals fused grains present in samples pressed at 150 °C but not in those at 20 °C. X-ray photoelectron spectroscopy and diffraction analysis show no significant difference in crystal structure or surface composition between 150 and 20 °C pressed samples, and the pellet densities are nearly identical. The ionic conductivity of 150 °C pressed samples is nearly invariant with operating pressure, while that at 20 °C has a strong operating pressure dependence. Nanoindentation on pellet surfaces shows a higher elastic modulus for the 150 vs 20 °C pellets. Overall, these results suggest that fabrication at 150 °C results in grain–grain fusion and motivate further study of the fabrication parameter space (e.g., pressure, temperature, time, and contacts) to find routes to <1 MPa operation of argyrodite structures.

Among energy storage devices, covalent organic polymers (COPs) are the prime choice as active electrode materials, which are held together by strong covalent bonds and offer notable advantages such as high specific surface area and exceptional chemical durability. However, certain COPs have limited conductivity and underwhelming electrochemical properties, which hinders their application in supercapacitors (SCs). To address these challenges, we successfully synthesized two types of porous organic polymers, PyTB-BBT COP and PyTB-Py COP, along with graphene oxide (GO) and single-walled carbon nanotubes (SWCNTs) named PyTB-BBT COP/GO, PyTB-BBT COP/SWCNTs, PyTB-Py COP/GO and PyTB-Py COP/SWCNTs, respectively via physical interaction [π–π stacking interactions]. The PyTB-BBT COP and PyTB-Py COP were initially prepared through a Schiff base reaction, using 4,4′,4″,4‴-(pyrene-1,3,6,8-tetrayltetrakis(ethyne-2,1-diyl))tetraaniline (PyTB-4NH₂) as a building block, which was reacted with 4,4′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzaldehyde (BBT-2CHO) for PyTB-BBT COP, and with 4,4′,4″,4‴-(pyrene-1,3,6,8-tetrayl)tetrabenzaldehyde for PyTB-Py COP. The successful synthesis of PyTB-BBT COP/GO, PyTB-BBT COP/SWCNTs, PyTB-Py COP/GO, and PyTB-Py COP/SWCNTs through π–π stacking interactions were verified using TEM and photoluminescence (PL) measurements. Notably, compared to their pristine counterparts, as well as PyTB-BBT COP/GO (5 wt %) and PyTB-Py COP/GO (5 wt %), the PyTB-BBT COP/SWCNTs (5 wt %) and PyTB-Py COP/SWCNTs (5 wt %) hybrids demonstrate remarkable promise as supercapacitor electrode materials. They exhibit specific capacitances of 185 and 342 F g^–1 at a current density of 0.5 A g^–1, retaining approximately 85% and 92% of their capacity after 10,000 cycles in a three-electrode supercapacitor setup. The outstanding electrochemical performance of the PyTB-Py COP/SWCNTs (5 wt %) hybrid could be caused by three key elements: strong π–π stacking interactions of SWCNTs and PyTB-Py COP, facilitated by the presence of two pyrene units in the PyTB-Py COP framework; the porous structure of PyTB-Py COP, which improves ion transport; and the excellent electron conductivity provided by the SWCNTs.

We report the microscopic mechanism of Na-ionic conduction and the role of the underlying crystal structure in the ionic conduction in the two-dimensional (2D) layered battery material Na₂Co₂TeO₆ by combined neutron diffraction and impedance spectroscopy studies. Na₂Co₂TeO₆ consists of Na⁺-ion layers in the ab plane, which are well separated by intermediate magnetic (Co/Te)O₆ layers along the c axis. Within the layers, the Na⁺ ions, resided in trigonal prismatic NaO₆ coordination, and are distributed over three partially occupied crystallographic sites. Our temperature-dependent neutron diffraction study ensures that the crystal symmetry remains invariant over 300–723 K, with a nominal change (∼2%) in the unit cell volume. Further, the soft-bond valence sum (BVS) analyses of neutron diffraction patterns reveal 2D ionic conduction pathways within the Na layers. The impedance data have been analyzed to estimate the interlinked parameters, viz., dc ionic conductivity, ac ionic conductivity, and diffusivity, in addition to electrical modulus and dielectric constant, illustrating the microscopic mechanism of Na-ionic conduction. The conduction mechanism of Na⁺ ions involves a correlated barrier hopping (CBH) process. The conduction of the Na⁺ ions is found to be both thermally and frequency activated. A significant enhancement (∼10³ times) of the conductivity has been observed upon increasing the temperature from 343 to 473 K. Further, our study demonstrates that the Na-ionic conduction of Na₂Co₂TeO₆ is highly influenced by a disordered arrangement and partial occupation of Na ions within the 2D layers. The present comprehensive study, thus, provides an insight into the microscopic understanding of the ionic conduction properties and its intercorrelations with the crystal structure. The present work is significant for the progress of battery research, especially in the fabrication of highly efficient battery materials.

The liquid electrolytes (LEs) in traditional lithium batteries present safety concerns. Solid polymer electrolytes (SPEs) have garnered increasing attention due to their nonvolatility, ease of processing, excellent mechanical properties, and stability. However, the performance of PEO-based solid-state batteries is often constrained by low ionic conductivity and poor mechanical strength. Therefore, we fabricated a nanofiber scaffold (PAN@UiO66) using electrospinning technology and then cast a solution containing zirconia (ZrO₂) fillers and bis(trifluoromethane)sulfonimide (LiTFSI), dispersed in poly(ethylene oxide) (PEO), onto the electrospun PAN@UiO66 scaffold to obtain a composite solid polymer electrolyte (CSPE, PZ/PAN@UiO66). The synergistic effect of the PAN@UiO66 scaffold and zirconia creates an amorphous-enriched region in the CSPE, providing uniform and abundant Lewis acid–base interaction sites, which reduce the crystallinity of the PEO-based solid electrolyte and enhance the diffusion and migration of lithium ions within the polymer. The components were physically characterized and electrochemically tested by using Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). The results indicate that the incorporation of PAN@UiO66 optimizes the lithium-ion transport behavior of PEO-based solid electrolytes and enhances their cycling stability. Specifically, at 60 °C, the lithium-ion transference number of the PAN@UiO66 nanofiber-enhanced composite solid polymer electrolyte (CSPE) increased from 0.20 to 0.40, the electrochemical voltage window expanded from 4.58 to 5.10 V, and the Li||Li symmetrical cell assembled with CSPE exhibited stable plating and stripping for over 670 h at a current density of 0.1 mA cm^–2. The assembled LFP||Li coin cell delivered an initial discharge capacity of 149.81 mAh g^–1 at 0.5C, with a capacity retention of 101.53% after 200 cycles. The LFP||Li pouch cell assembled with CSPE exhibited a discharge capacity of 113.21 mAh g^–1 at 0.5C and stable cycling for 100 cycles, demonstrating the commercial potential of the composite solid-state electrolyte.

LiBH₄ has attracted significant interest due to its high-hydrogen storage capacity (18.5 wt % H₂). However, its practical application is severely impeded by the high dehydrogenation temperature, sluggish hydrogen release kinetics, and poor reversibility. In this work, a graphene-supported rodlike FeF₂/FeO_X additive (FeF₂/FeO_X@G) is prepared and introduced into LiHB₄ by a simple ball-milling. With an optimized LiBH₄-to-FeF₂/FeO_X@G weight ratio of 7:3, the 7LiBH₄-3(FeF₂/FeO_X@G) system starts dehydrogenation at a low temperature of 100 °C below and 8.7 wt % H₂ is released upon heating to 400 °C, while 1.1 wt % H₂ is released for pristine LiBH₄. Moreover, the system releases rapidly 7.0 wt % H₂ at 350 °C within 80 min, and a dehydrogenation capacity of 5.5 wt % is reached after 10 reversible hydrogen absorption and desorption cycles. The in situ formed FeB, Li₃BO₃, and Fe₂B during the first dehydrogenation process acted as a synergistic catalysis, effectively improving the reversible hydrogen storage of LiBH₄. This work provides insights into the design of unique additives to introduce multiple catalyst synergies to enhance the hydrogen storage performance of LiBH₄.

Transition metal sulfides are emerging as promising materials for supercapacitor applications due to their excellent conductivity, high theoretical capacities, and stability. Exploring these materials, along with enhancements like doping of carbonaceous materials, could lead to high-performance solutions that address the growing need for renewable energy technologies and sustainable energy storage systems. Herein, mixed metal sulfide Cu₂S/Co₃S₄ composites with varying percentages of multiwalled carbon nanotubes (MWCNTs) were synthesized through a facile one-step hydrothermal method. The resulting materials displayed outstanding electrochemical behavior. This performance was optimized by tuning the weight percentage of CNTs doped in the metal sulfide scaffold. Among the prepared nanocomposites, i.e., Cu₂S/Co₃S₄@CNT-x, referred to as CCS@CNT-x (where x is the wt % of CNT), CCS@CNT-10 showed the maximum specific capacitance (C_sp) of 960 F g^–1 at 1 A g^–1 (specific capacity, C_s of 638 C g^–1), as revealed from electrochemical measurements. The as-fabricated device CCS@CNT-10//activated carbon sustained a broad potential window of 1.7 V, showing a high power density of 17000 W kg^–1 along with a high energy density of 68 Wh kg^–1 at 20 A g^–1. The device was able to maintain its cyclic stability up to 95% even after 20,000 cycles. The exceptional electrochemical performance of the device can be attributed to the synergistic interactions between Cu₂S and Co₃S₄, combined with the highly conductive interconnected network created by CNT incorporation. This combination facilitates efficient redox reactions at the electrode–electrolyte interface and accelerates electron transport throughout the material.

Aluminum (Al) is a highly promising material for lithium-ion batteries (LIBs) anodes due to its high specific capacity, excellent electrical conductivity, and low cost. However, its practical application is hindered by significant volume changes during cycling, which cause electrode crushing and numerous penetration cracks. In this study, we design a laminated Al foil and incorporated it into lithium–aluminum (Li//Al) half-cells, which retain a long cyclic stability of 300 cycles at a current density of 1 mA cm^–2 and an areal capacity of 1 mA h cm^–2. The laminated Al foil exhibits denser grain boundaries, leading to enhanced lithiation uniformity. Additionally, the laminated structure effectively alleviates stress concentration during lithiation and delithiation, diverting major cracks into smaller, multidirectional ones. This structural improvement significantly enhances the stability of the Al foil anode during cycling. The findings offer valuable insights for optimizing metal foil anode designs, which could contribute to advancements in LIBs technology, particularly in improving specific energy.

The n-type Mg₃(Sb,Bi)₂-based thermoelectric materials are promising candidates for medium-temperature power generation due to their low cost, nontoxicity, and high performance. However, their large-scale application in thermoelectric devices is significantly hindered by poor long-term stability, resulting from electrode interface degradation. Effective contact interfaces in thermoelectric devices require high bonding strength, low interfacial resistivity, and exceptional stability. Therefore, the development of efficient and reliable thermoelectric interface materials is crucial for the practical application of these devices. Conventional approaches to forming interfacial barrier layers mainly rely on thermodynamic equilibrium, which often overlook the critical roles of interfacial reactions and diffusion kinetics. In this study, molecular dynamics simulations were employed to uncover the underlying mechanisms responsible for the high stability of the Mg₂Ni barrier layer and its interface with thermoelectric materials. The Mg₂Ni/Mg_3.21Sb_1.5Bi_0.5Y_0.04 thermoelectric device exhibited excellent performance, with a low contact resistance of 11 μΩ·cm², a high output power density of 1.2 W·cm^–2, and an energy conversion efficiency of 5% at a temperature difference of ΔT = 373 K. This strategy is applicable to other thermoelectric materials, offering valuable insights for designing barrier layers in diverse thermoelectric systems.

Cu₂₂Sn₁₀S₃₂ thermoelectric materials show great potential among Cu-based chalcogenides due to their high power factor and environmentally friendly chemical composition. However, its ultrahigh intrinsic hole carrier concentration deteriorates the thermoelectric performance. In this work, a synergistic strategy combining doping and nanostructure engineering is proposed to optimize the thermoelectric performance of Cu₂₂Sn₁₀S₃₂. On the one hand, Sb is doped into the Sn sublattice to provide donors, which compensate hole carriers and thus reduces the carrier concentration, leading to an optimized power factor. On the other hand, the composite of Cu₂₂Sn₁₀S₃₂ with Sb₂O₅ results in the simultaneous doping of Sb elements and introduction of SnO₂ nanoparticles. While maintaining the optimized electrical performance, the SnO₂ nanoparticles as additional phonon scattering centers significantly lower the lattice thermal conductivity of Cu₂₂Sn₁₀S₃₂, ultimately achieving a maximum zT value of 0.68 at 723 K. Our results demonstrate that cation substitutional doping and nanostructure engineering can effectively enhance the thermoelectric performance of Cu₂₂Sn₁₀S₃₂.

The energy density and cycling life of silicon-based lithium-ion batteries (LIBs) rapidly approach their designed targets. However, their calendar life still fails to meet the requirements for long-term stability. In this study, Si/C||LiNi_0.8Mn_0.1Co_0.1O₂ (NCM811) batteries have been constructed from Si/C composites with no graphite and Ni-rich NCM811. The electrolytes used propylene carbonate (PC) or ethylene carbonate (EC) as the base solvent, supplemented with fluoroethylene carbonate (FEC). After 800 cycles, the PC-based electrolyte battery retained 79.7% capacity compared to 70.2% for the EC-based electrolyte. Following storage at 60 °C for 7 days, the PC-based electrolyte battery exhibited a 95% capacity recovery, 56% resistance growth, and 51% gas generation. The EC-based electrolyte battery showed 91%, 70%, and 101%, respectively. Atomic force microscopy (AFM) analyses and Young’s modulus measurements revealed that the PC-based electrolyte facilitated the formation of a thinner, smoother, and denser solid electrolyte interphase (SEI) on the Si/C surface. Furthermore, for the PC-based electrolyte, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) results showed PC promoted FEC reactions, forming a dense, LiF-rich SEI. In contrast, for the EC-based electrolyte, the EC and FEC jointly reacted to form a thicker SEI. Molecular dynamics (MD) simulations showed that for the PC-based electrolyte, approximately 20.4% of the FEC molecules participated in the Li⁺ solvation structure, which was more than the 17.1% obtained for the EC-based electrolyte. Thus, the synergistic effect of PC and FEC resulted in an effective formation of a more stable SEI, which enhanced the cycling performance and calendar life of Si/C. This study offers an economical and effective commercial electrolyte solution for high-energy-density Si/C-based LIBs.

Scientific interest in organic solar cells (OSCs) has increased significantly in recent years. This surge is largely due to advances in A-DA′D-A-type small molecule acceptors (SMAs), which have played a key role in improving the power conversion efficiency (PCE) of OSC devices. Nevertheless, there is a prevailing need to continue exploring avenues that would further elevate the performance of OSCs, particularly improving their open-circuit voltage (V_OC). The structural modification of the fused-ring electron-withdrawing A′ unit with the quinoxaline unit is an approach that holds considerable promise for enhancing the V_OC and PCE of A-DA′D-A type molecules. Furthermore, it has been demonstrated that the incorporation of bromine atoms into SMAs can result in the synthesis of highly prospective SMAs. This is attributable to the fact that bromine atoms possess lower electronegativity, larger atomic dimensions, and a comparatively more straightforward and cost-effective synthetic procedure compared to the commonly used fluorine and chlorine atoms. To develop promising brominated SMAs to enhance the V_OC of OSCs, two alkoxypheny-substituted quinoxaline-based A-DA′D-A molecules (BQ-2FBr and BQ-2Cl-FBr) were synthesized, with the former sealed with (5-bromo-4-fluoro-3-oxy-2,3-dihydro-1H-indole-1-ylidene)malonitrile (FBr-INCN) unit and the latter sealed with 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malonitrile (2Cl-INCN) and FBr-INCN units simultaneously. The symmetrical molecule BQ-2FBr possesses an elevated LUMO energy level, while the asymmetrical molecule BQ-2Cl-FBr displays a broadened absorption spectrum with a high extinction coefficient and better molecular stacking property. When combined with PM6, the BQ-2FBr device achieves a very good V_OC of 0.944 V and a moderate PCE of 10.11%. Despite a decline in the V_OC of the PM6:BQ-2Cl-FBr device to 0.928 V, simultaneous enhancement in the short circuit current density (J_SC) and fill factor (FF) was observed. This resulted in an augmented PCE of 11.54%, a development primarily attributed to the improved charge collection and exciton dissociation properties, suppression of charge recombination, enhancement of molecular stacking property and better morphology of the blend film, and acceleration of exciton diffusion time. This work describes the important influence of distinct brominated terminal groups on the photovoltaic performance of alkoxyphenyl-substituted quinoxalinyl A-DA′D-A SMAs, which may offer a useful structural guideline for the development of promising SMAs for high-efficiency and large V_OC OSCs.

Lithium–sulfur (Li–S) battery technology provides one of the most promising alternatives to conventional lithium-ion batteries (LIBs). However, these Li–S batteries suffer from polysulfide dissolution leading to a shuttle effect, insulating nature, and volume expansion associated with sulfur particles. To mitigate these challenges, we present an approach of using sulfur nanoparticle (S NP)-reinforced patterned vertically aligned carbon nanotube (S@P-VACNT)-based microstructures as S cathodes for Li–S batteries. Engineered P-VACNT microstructures offer efficient charge transport pathways, trap lithium polysulfides (LiPSs), and reduce volume expansion of S NPs, which improve the performance of Li–S batteries. The demonstrated S@P-VACNT cathodes have delivered an excellent stable average discharge-specific capacity of ∼1030 mAhg^–1 for 100 cycles at 0.1 C with an average capacity decay of only ∼0.043% per cycle. Additionally, S cathodes have shown a remarkable average discharge-specific capacity of ∼890.03 mAh g^–1 for 500 cycles at 1.0 C, with a high-capacity retention of ∼99.81%, and ∼636.46 mAhg^–1 for 1000 cycles at 2.0 C. The structural integrity of P-VACNT and LiPS trapping is confirmed by postmortem FESEM and XPS studies of cycled cathodes, respectively. The demonstrated S@P-VACNT cathodes provide an out-of-the-box solution to overcome the long-standing technical challenges associated with Li–S batteries.

Using a urea-assisted precipitation method, we synthesized CoAl-layered double hydroxide (LDH) nanosheets that were uniformly aligned perpendicular to the surface of the silicon wafer. Then, a carbon nanocomposite consisting of vertically aligned carbon nanotubes (VACNTs) and graphene nanoflakes (GNFs) was prepared by plasma-enhanced chemical vapor deposition (PECVD) using LDH as the catalyst precursor. After heat treatment, LDH formed a layered double oxide (LDO). The VACNTs were attached to both sides of the LDO nanosheets, while GNFs were uniformly distributed on the VACNTs’ surface. Next, the three-dimensional (3D) GNF/VACNT-LDO material was used as a conductive agent for the LiFePO₄ cathode with a practical commercialized state-of-the-art cathode recipe of lithium-ion batteries. The results showed that the cathode had a high specific capacity and excellent cycling stability. The discharge specific capacity was as high as 168.6 mAh g^–1 at a current rate of 0.2 C. Amazingly, when the current rate was increased to 10 C, the discharge capacity reached 105.3 mAh g^–1, which was much higher than that with the conventional conductive agent Super P (65.1 mAh g^–1). After 500 cycles at 0.5 C current density, the discharge specific capacity was still 118.2 mAh g^–1, with a capacity retention rate of 72.7% and an average capacity loss of only 0.089 mAh g^–1 per cycle. The excellent rate performance and cycling stability of the LFP cathode are largely attributed to the GNF/VACNT-LDO. The unique 3D conductive network constructed by GNF/VACNT-LDO can greatly increase the electron transport rate and accelerate the shuttling of Li⁺ between the electrolyte and the electrode material.

This work presents the development of solid polymer electrolytes (SPEs) for next-generation solid-state batteries. Solid polymer electrolytes were prepared based on a polymer matrix (poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP)) doped with 16 wt % ceramic particles (barium titanate oxide (BTO), barium strontium titanate (BST), and lead zirconate titanate (PZT)) and an ionic liquid (IL, [PMPyr][TFSI]) at 40 wt %. The ionic liquid allows improvement of the ionic conductivity of the system, whereas the ceramic particles are included to enhance the mechanical strength and thermal stability of the system. The physical, morphological, and electrochemical characteristics of the SPEs were studied. The addition of ceramic particles and ionic liquids does not affect the morphology, which remains a compact morphology. In the same way, the degree of crystallinity, polymer phase, and thermal properties of the SPE remain similar to the pristine polymer after filler addition. The inclusion of both ceramic particles and the ionic liquid allowed improvement of battery performance. Ionic conductivity in the order of 2.41 × 10^–5 S cm^–1 was achieved, accompanied by a battery capacity performance very close to theoretical values. Battery performance with PVDF-HFP/BST/IL (153 mAh g^–1) and PVDF-HFP/BTO/IL (148.2 mAh g^–1) composites proved to be successful in long-life cycling, bearing a higher capacity and stability compared to PVDF-HFP/IL (121.3 mAh g^–1). When varying C rates were applied, the PVDF-HFP/BST/IL sample presented superior results, revealing higher stability when compared to the other SPE samples. In conclusion, the fine-tuning of the ceramic particle type within SPE formulations offers an avenue for battery performance optimization. In particular, the inclusion of BST in the hybrid SPE composite allows improvement of battery cycling stability.

In contrast to the previous assumption that manganese (hydr)oxides in the absence of other metal ions indicate high overpotential to catalyze the oxygen-evolution reaction (OER) under neutral conditions, this study reveals that layered manganese oxide exhibits OER activity at the Mn(III) to Mn(IV) oxidation peak post charge accumulation. Although low current density was observed, this activity is realized at an exceptionally low overpotential of 20 mV within a phosphate buffer solution. A detailed mechanistic proposal for OER within this low-overpotential domain is presented, substantiated by in situ visible and Raman spectroscopic analysis focused on the Mn(III) to Mn(IV) transition and surrounding OER region. The quantification of the evolved oxygen and analysis of redox-active Mn ion concentrations near the redox peak yield a calculated turnover frequency of 3.8 × 10^–3 s^–1 at 1.35 V. The observed reduction in overpotential is ascribed to the complicated interaction between the OER process and charge accumulation, echoing mechanisms characteristic of natural systems in the oxygen-evolving complex in photosystem II, which collectively enable the remarkably low overpotential. These findings offer critical insights for advancing highly efficient and robust electrocatalysts for OER in water-splitting applications, with substantial implications for the future of energy conversion and storage technologies.

This study reports the synthesis of monoclinic clinobisvanite BiVO₄ crystals with well-defined {010} and {110} facets and nanometer sizes through controlled reactant addition and hydrothermal treatment. By adjustment of the Bi³⁺ precursor addition rate, nanoplates with significantly reduced edge length and thickness were obtained compared to conventional microplates. The formation process involves the nucleation of surfactant-coated tetragonal zircon BiVO₄ nanocrystals, which aggregate into spheroids before being transformed into monoclinic clinobisvanite plates. A proposed model explains this size-tuning mechanism through partial dissolution, phase transformation, and facet-selective growth. Reducing the size of tetragonal zircon BiVO₄ spheroids enhanced photocatalytic water oxidation, while for monoclinic clinobisvanite BiVO₄ plates, size reduction had the opposite effect. Photoelectrochemical analysis revealed a shift from n-type behavior in microplates to p-type behavior in nanoplates under negative bias. These findings highlight the need to integrate size control with surface chemistry, bulk doping, and defect engineering to optimize BiVO₄ for catalytic and electronic applications.

Mg₃Sb₂ Zintl compounds have emerged as promising thermoelectric materials due to their favorable electronic structures and low lattice thermal conductivity. However, strong carrier scattering, including ionized impurity and grain boundary scattering, suppresses mobility and limits the power factor. This study reveals that Zn doping plays a crucial role in tuning carrier scattering mechanisms in n-type Mg₃(Sb,Bi)₂. The substitution of Mg with Zn weakens ionized impurity scattering, facilitating charge transport and increasing carrier mobility from ∼72 to ∼135 cm² V^–1 s^–1. As a result, a high power factor of ∼2089 μW m^–1 K^–2 is achieved at 573 K in Mg_3.155Zn_0.045Sb_1.5Bi_0.49Te_0.01. Furthermore, Zn incorporation introduces localized lattice distortions and promotes the formation of high-density dislocations, which intensify phonon scattering and significantly suppress lattice thermal conductivity to ∼0.54 W m^–1 K^–1 at 773 K. These synergistic enhancements contribute to an optimized thermoelectric performance, yielding a peak ZT of 1.71 at 773 K and an average ZT of 1.21. The estimated conversion efficiency reaches 13% under a 470 K temperature gradient, highlighting Zn doping as an effective strategy for advancing Mg₃(Sb,Bi)₂-based thermoelectric materials toward high-temperature energy harvesting applications.

Luminescence in metal–organic frameworks (MOFs) typically has one of three fundamental origins: emission from ligands, metal clusters, and encapsulated guests. Photophysical processes such as energy transfer or charge transfer can further modulate the emission profile. However, as the MOF structure becomes more complex, it can become increasingly difficult to pinpoint the origin of the emission. Herein, we report on the energy transfer behavior of multicomponent zinc-based frameworks from the MUF-77 family, which combine three luminescent, aromatic ligands and Zn₄O nodes. Each ligand has distinct photophysics and energy transfer behavior upon photoexcitation. Time-resolved photoluminescence spectroscopy on the nanosecond and picosecond time scales reveals the specific interligand energy pathways that influence the emission profile. Fluence-dependent measurements uncover both bimolecular and higher-order recombination in MUF-77. The long lifetimes and low bimolecular recombination rate point to modest exciton diffusion alongside higher-order exciton-charge annihilation in these systems.

Leveraging density functional theory, deep potential model, and grand potential phase diagram analysis, we have developed a promising solid-state electrolyte based on sodium chloride, Na₃La₃GdSmCl₁₈ (NLGSC). This material demonstrates outstanding stability in thermal, dynamical, mechanical, and thermodynamic aspects, complemented by a wide band gap of 5.6 eV and excellent ductility with a Pugh’s ratio of 2.30. Importantly, NLGSC achieves a high ionic conductivity of 3.00 mS/cm at 300 K, a low activation energy of 0.24 eV, and a migration barrier of only 0.20 eV along the crystallographic c-axis. Furthermore, it displays a broad electrochemical stability window spanning 0.65 to 3.78 V and superior chemical compatibility with high-voltage cathode materials such as Na₂FePO₄F, Na₃V₂(PO₄)₃, and Na₃V₂P₂O₈F₃. These findings establish NLGSC as a promising solid-state electrolyte for Na-ion batteries, further expanding the applications of the recently synthesized chloride superionic conductors [Nature 2023, 616, and 77].

The study of luminous materials having the capacity to emit light via many emission pathways has become a priority in materials research, spurred by the demand for increased performance in optoelectronic and medical applications. Traditional luminous materials are usually limited to single emission channels, restricting their performance and applicability. Multiemissive materials, on the other hand, can display fluorescence, charge transfer (CT) emission, room temperature phosphorescence (RTP), and delayed fluorescence (DF), providing a potential means to overcome these limits. In this study, we reported a class of 9-fluorenone derivatives tailored to utilize these diverse emission mechanisms. We acquired exact control over the relative contributions of each emission pathway by purposely modifying the molecular architecture─for example, adding heavy atoms to boost spin–orbit coupling and introducing electron-withdrawing groups to influence electronic states. The resulting compounds possessed high fluorescence quantum yields, extended RTP durations in the microsecond region, and efficient DF lifetimes in the millisecond domain. Furthermore, by altering molecular structure and external environmental circumstances, their emission spectra can be fine-tuned from visible to near-infrared. In addition, time-dependent density functional theory (TDDFT) calculations were performed to investigate the excited states and their roles in the different emission channels, providing deeper insight into the mechanisms underlying the observed photophysical behaviors. The adjustable character of these materials is further emphasized by their sensitivity to external stimuli such as solvent polarity and temperature, allowing for the selective enhancement of specific emissive routes. These 9-fluorenone derivatives are suited for advanced applications in organic light-emitting diodes (OLEDs), bioimaging, and molecular sensing technologies due to their stimuli-responsive features. Our findings emphasize the importance of combining molecular design and environmental factors to optimize multipathway emission, providing a versatile platform for the development of next-generation luminescent materials with broad applicability in both fundamental research and practical applications.