The effect of modifying V₂C using transition metals (TMs) (Ti, Ni, Zr, and Nb) on the MgH₂ dehydrogenation properties was investigated using the density functional theory (DFT). The adsorption energy, dehydrogenation energy, and electronic structure of MgH₂ on TM (Ti, Ni, Zr, and Nb)@V₂C were calculated. The results showed that TM atoms tended to occupy the face-centered cubic sites of V₂C. MgH₂ adsorption on V₂C was improved by adding a TM and the order of the adsorption energy was as follows: Ni@V₂C > Ti@V₂C > Zr@V₂C > Nb@V₂C > V₂C. An orbital hybridization peak between H and TM atoms was observed in the electronic structure of MgH₂ on TM (Ti, Ni, Zr, and Nb)@V₂C. The addition of a TM supported on V₂C substantially improved the dehydrogenation energy of (MgH₂)₄ clusters, and the order of improvement was Ni@V₂C > Ti@V₂C > Nb@V₂C > Zr@V₂C. The dehydrogenation energy of (MgH₂)₄ clusters on Ni@V₂C was lower than that of pure (MgH₂)₄ clusters and (MgH₂)₄ clusters on V₂C, by 1.60 and 1.11 eV, respectively. TM@V₂C combinations had significantly enhanced MgH₂ dehydrogenation, providing theoretical justification for conducting experiments to develop novel high-performance catalysts.

We employed a one-step hydrothermal method to in situ grow spherical NiS₂ nanoparticles on the surface of MXene, successfully constructing a NiS₂–MXene hybrid composite. This study demonstrates that the integration of a NiS₂–MXene hybrid composite into MgH₂ substantially improves its hydrogen storage performance. Specifically, the composite reduces the initial dehydrogenation temperature of MgH₂ by 118°C, lowering it from 310°C (pure MgH₂) to 192°C. At 300°C, it can release 5.87wt% of hydrogen within 12 min. Furthermore, it demonstrates the ability to absorb hydrogen under ambient temperature conditions, with approximately 2.96wt% of hydrogen being absorbed as the temperature increases from room temperature to 50°C. The activation energies for hydrogenation and dehydrogenation of the NiS₂–MXene–MgH₂ composite reduced by 33.7 and 40.6 kJ·mol⁻¹, respectively, in comparison to those of pure MgH₂. Mechanistic studies demonstrate that NiS₂–MXene enhances hydrogen storage performance through multiple synergistic effects. Specifically, the multivalent titanium in MXene establishes efficient electron transport pathways, promoting hydrogen binding and dissociation. Moreover, the in situ formation of Mg₂Ni/Mg₂NiH₄ and MgS creates numerous phase interfaces, offering abundant active sites that facilitate both the dissociation and recombination of hydrogen molecules. Furthermore, the high specific surface area of MXene effectively inhibits agglomeration between the catalyst and Mg/MgH₂, thereby maintaining structural stability and reactivity.

Magnesium hydride (MgH₂) is a highly attractive candidate for solid-state hydrogen storage because of its high mass density, excellent cyclic stability, and low cost. However, the commercialization of MgH₂ has been hindered by its sluggish hydrogen sorption kinetics and elevated operating temperatures. In this study, vanadium hydride nanoparticles (VH_x) adhered to Ti₃C₂ composite catalyst was synthesized by ball milling to improve the hydrogen storage properties of MgH₂. The onset dehydrogenation temperature of the MgH₂ + 10wt% VH_x@Ti₃C₂ composite decreased from 267.6 to 190.3°C. In addition, the MgH₂ + 10wt% VH_x@Ti₃C₂ composite could release 6.72wt% hydrogen within 10 min at 290°C. By comparison, pure MgH₂ started to release hydrogen at 267.6°C, whereas only 0.29wt% hydrogen was released under the same conditions. After 20 cycles, more than 95% of the initial hydrogen absorption and desorption capacities were retained, indicating that the MgH₂ + 10wt% VH_x@Ti₃C₂ composite exhibited good cycling performance. Investigation of the catalytic mechanism demonstrated that the layered structure of Ti₃C₂ served as a matrix supplying a large number of active sites, and VH_x functioned as a “hydrogen pump” to accelerate the migration of H ions, thereby facilitating the hydrogen absorption and desorption processes of MgH₂ and enhancing its hydrogen storage properties. This study provides a viable strategy for designing vanadium-based catalysts to improve solid-state hydrogen storage materials.

The current study presents a composite material based on magnesium hydride with the addition of aluminum, obtained by the method of electrical explosion of wires (EEW). The study demonstrated that the material has improved hydrogen interaction characteristics, which is associated with its core–shell structure, defect formation during milling, and the hydrogenation process. The combination of these factors contributes to a decrease in the activation energy of desorption from (161 ± 2) to (109 ± 1) kJ/mol, and consequently, to a reduction in operating temperatures. The data obtained are correlate with a model in which mechanochemical treatment and the formation of Mg–Al interfaces induce a developed network of vacancies, dislocations, and increased microstrains. Based on all of the above, a corresponding mechanism for low-temperature hydrogen desorption from the composite was described.

This study investigates the impact of silver (Ag) substitution on the microstructure and hydrogen storage properties of an Mg₂Ni-based alloy. Density functional theory (DFT) calculations as well as universal machine learning interatomic potentials are used to explore how Ag substitution leads to a decreased hydride desorption energy. Experimental analysis of arc-melted Mg_1.95Ag_0.05Ni alloys and melt-spun Mg_1.95Ag_0.05Ni ribbons reveals structural changes between the two different production methods. X-ray diffraction (XRD), scanning electron microscope (SEM), differential thermal analysis (DTA), thermogravimetric analysis (TGA), and transmission electron microscope (TEM) confirm refined microstructures. In addition, hydrogen properties of melt-spun ribbons were measured with Sievert type and electrochemical device. The Sieverts-type measurement demonstrates about 3wt% H₂ absorption and desorption, while electrochemical measurements show an initial discharge capacity of 80 mAh/g, with gradual fading over cycles. X-ray photoelectron spectroscopy (XPS) unambiguously confirms Ag substitution and provides detailed insight into surface oxidation processes induced by prolonged exposure to ambient conditions. The results demonstrate that Ag incorporation plays a key role in tailoring the microstructure and significantly enhancing the hydrogen storage performance.

Solid-solution magnesium-based alloys have garnered significant attention for hydrogen storage applications. However, their practical implementation has been limited by their stable thermodynamic properties and sluggish kinetics. Herein, we report a nanoengineering approach to simultaneously enhance the kinetic and thermodynamic properties of Mg-based solid-solution alloys. Using Mg(In) alloys as a model system, we demonstrate this positive size effect through a two-step fabrication process. First, the Mg_0.9In_0.1 alloy was synthesized via ball milling combined with absorption/desorption cycles. Subsequently, the alloy was subjected to high-pressure milling under a 4 MPa H₂ atmosphere with immiscible Mn at a controlled molar ratio, resulting in Mg(In) nanograins uniformly embedded within the Mn-composite matrix (denoted as (Mg_0.9In_0.1)_xMn_1−x). The (Mg_0.9In_0.1)_0.25Mn_0.75 nanocomposite, with an average grain size of ∼61 nm, demonstrated superior hydrogen storage properties. Compared with pure MgH₂, this material exhibits much lower onset and peak temperatures for hydrogen release, at ∼120 and ∼240°C, respectively. Moreover, enhanced kinetic performance, with a significantly lower activation energy of ∼78.34 kJ/mol, and improved cycling stability, with 97% retention after 50 cycles, are achieved due to the Mg(In) nanograins, which remain well-preserved even upon multiple cycles. This study highlights that the synergistic combination of solid-solution formation and nanoscale engineering can effectively modify the thermodynamic and kinetic properties of Mg-based hydrogen storage alloys, offering a promising approach for the development of high-performance magnesium-alloy hydrogen storage materials.

Accurate determination of the state of hydrogen (SOH) in solid-state hydrogen storage materials is essential not only for optimizing hydrogen release kinetics and enhancing storage efficiency but also for ensuring system safety in practical applications. While most existing studies have concentrated on thermodynamics and kinetics, direct monitoring of residual hydrogen content, a parameter of critical engineering relevance, has rarely been reported. This highlights the urgent need to realize online SOH detection through new physical properties. In this study, we propose a non-invasive, real-time SOH monitoring strategy for magnesium hydride (MgH₂), based on optical properties and combining density functional theory (DFT)-based optical calculations with experimental validation. Using DFT, the optical properties of MgH₂ and its dehydrogenated form (Mg) were systematically calculated across the infrared, visible, and ultraviolet spectral ranges. Theoretical results revealed strong linear correlations between SOH and specific optical parameters, such as reflectance at 1200 nm and 550 nm and refractive index at 250 nm, with the coefficient of determination exceeding 0.99 and mean absolute errors below 0.05. To validate these predictions, reflectance measurements were conducted at 940 nm, a wavelength identified as highly sensitive to hydrogenation, and a consistent decrease in reflectance with increasing hydrogen uptake was observed. The underlying mechanism was attributed to band structure evolution and electron density redistribution, supported by density of states analysis and Drude model interpretations. This work establishes a robust theoretical and experimental framework for optical SOH diagnostics, emphasizes the importance of residual hydrogen detection for advancing solid-state hydrogen storage from fundamental research toward practical engineering applications, and provides new insights into the design of intelligent, optically responsive hydrogen storage systems, paving the way for the development of spectroscopic SOH sensors in next-generation hydrogen energy technologies.

LiAlH₄ is hindered for practical hydrogen storage by its high decomposition temperatures, slow kinetics, and poor reversibility. To address the kinetic issues, this study introduces a tubular g-C₃N₄-supported NiFe-layered double hydroxide (g-C₃N₄@NiFe-LDH) nanocomposite as a catalytic dopant for LiAlH₄. The composite, synthesized via solvothermal and pyrolysis methods, features a well-defined tubular morphology (∼3 µm in length, ∼200 nm in diameter), which facilitates its homogeneous dispersion and intimate interfacial contact with LiAlH₄ during ball milling. Doping with 7wt% of this catalyst dramatically enhances the dehydrogenation kinetics of LiAlH₄. The onset dehydrogenation temperature is lowered to 79.2°C, and 6.8wt% of hydrogen is released in two steps. Kissinger analysis reveals that the apparent activation energies for these steps are reduced by 43.0% and 54.8%, respectively, demonstrating significantly improved dehydrogenation kinetics. Mechanistic studies suggest that the synergistic effect between the g-C₃N₄ support and NiFe-LDH, along with the potential in-situ formation of active interfacial species during dehydrogenation, contributes to this improvement.

LiBH₄, a solid-state hydrogen storage material with ultra-high theoretical hydrogen capacity, is seriously hindered for the practical applications by its high thermodynamic stability and slow hydrogen desorption kinetics. Herein, the dehydrogenation properties of LiBH₄ are remarkably improved by confinement in the porous (Cu,Ni)/Cu₂O heterostructure (np-(Cu,Ni)/Cu₂O), which was achieved using a novel two-step method containing dealloying of Mg–Cu–Ni precursor alloy to form the porous (Cu,Ni) solid solution, followed by micro-oxidation under air conditions. Hydrogen release from the constructed LiBH₄@np-(Cu,Ni)/Cu₂O (1:2, mass ratio) system begins at approximately 80°C and ends before 380°C, with 12.5wt% of hydrogen desorbed. Moreover, the apparent dehydrogenation activation energy has been reduced to 44.2 kJ/mol. After rehydrogenation at 400°C under 8 MPa hydrogen pressure, the LiBH₄@np-(Cu,Ni)/Cu₂O (1:2, mass ratio) system can release 3.6wt% of hydrogen during the second dehydrogenation process. These findings show that the synergistic effect of confinement and heterostructure catalysis provided by the porous metal derivatives can greatly enhance the hydrogen storage properties of LiBH₄.

This work investigated the crystal structure, hydrogen storage, and electrochemical properties of the Ti_0.2Zr_0.8(V_0.2Mn_0.8)_1−xM_xNi_1.0 (M = Al, Fe; x = 0, 0.05, 0.1) Zr-rich AB₂ alloys. Rietveld refinement of X-ray diffraction (XRD) revealed that C14 phase abundance increased with Al content, while Fe promoted C15 phase formation, accompanied by a variation in the lattice constants. Hydrogen storage experiments showed C15 phase abundance positively correlated with maximum adsorption capacity, while plateau pressures were negatively correlated with lattice constants. The Fe_0.1 alloy exhibited the largest adsorption capacity and the highest plateau pressure, whereas the Al_0.1 alloy displayed opposite characteristics. All alloys demonstrated rapid hydrogen adsorption kinetics, reaching 98% capacity within 1 min after 5 activation cycles, retaining no obvious capacity decay after 20 cycles. Electrochemical studies indicated that Fe doping enhanced discharge capacity and high-rate discharge (HRD) performance due to increased C15 phase abundance. Electrochemical kinetics revealed that the improved HRD performance can be attributed to the enhanced electrocatalytic performance and hydrogen diffusion rate in Fe-doped alloys. This work provides a systematic analysis of how Al and Fe doping influences the AB₂-type Laves phase alloys, offering theoretical and experimental evidence for alloy design and optimization.

This study focused on improving the activation property and cycling stability of V₇₈Ti₆Cr₁₆ alloy through trace Ce doping. V₇₈Ti₆Cr₁₆Ce_x (x = 0, 0.2, 0.4) alloys were prepared by arc melting. The activation property, the kinetic and thermodynamic properties, the cycling stability and the cycling stability mechanism of the prepared alloys were investigated. The results show that trace Ce doping significantly improves the activation performance of the alloy. The kinetics changed little and the thermodynamics changed a little by trace Ce doping. Crucially, trace Ce doping remarkably improved cycling stability of the alloy. V₇₈Ti₆Cr₁₆Ce_0.2 exhibited a capacity retention rate of 97.43% after 400 cycles, substantially higher than the 93.06% of undoped alloy. Even after 1000 cycles, V₇₈Ti₆Cr₁₆Ce_0.2 maintained higher than 90% retention, demonstrating excellent cycling stability for practical applications. X-ray diffraction and compressing test reveal that Ce doping effectively improves the crystal structure of the alloys by increasing the cell volume and enhancing the mechanical properties of the alloy, thereby improving the structure stability of the alloy during cycling. Transmission electron microscope analysis indicated that the defect density progressively increases with cycling in undoped alloy, which is the main reason for the capacity decay. But the defect density is much less in V₇₈Ti₆Cr₁₆Ce_0.2 alloy compared with undoped alloy, which contributes to its superior capacity retention rate. This work provides a new strategy for enhancing hydrogen storage properties via trace rare-earth doping.

The thermodynamic and kinetic properties of body-centered-cubic (BCC) hydrogen storage alloys highly depend on their chemical compositions, making high-entropy alloying a promising strategy for performance optimization. However, clarifying how multi-principal element compositions regulate multiscale structures and thereby influence their hydrogen storage performance remains challenging, which limits the rational design of high-performance BCC high-entropy alloys (HEAs). This review provides a comprehensive overview of the recent advances in BCC HEAs for hydrogen storage, with emphasis on the multiscale regulation of their thermodynamics and kinetics. Empirical descriptor-guided composition screening, thermodynamic modeling based on the CALculation of PHAse Diagrams, and data-driven and machine learning-assisted approaches are discussed. In addition, the roles of melting-based processing, mechanical alloying, and emerging fabrication strategies in controlling the chemical homogeneity, defect structures, and microstructural stability of materials are examined. The hydrogen storage performance is analyzed in terms of activation behavior, thermodynamics, kinetics, and cyclic stability, with a focus on the underlying governing factors and mechanistic origins. Finally, prospective challenges and research directions are outlined to guide the design and processing of BCC HEAs.

Intermetallic compounds (IMCs) are considered desirable materials for hydrogen storage. However, traditional hydrogen-storage IMCs have many shortcomings. High-entropy alloys (HEAs), which are composed of multiple metallic elements, exhibit significant lattice distortion and large interstitial sites, making them a promising class of hydrogen storage materials. Among the HEAs used for hydrogen storage, high-entropy intermetallics (HEIs) have shown great potential for hydrogen absorption kinetics and cycling stability, particularly for room-temperature hydrogen storage. This review systematically summarizes research progress on HEIs for hydrogen storage. It first presents a statistical analysis of composition design methods for these alloys, including empirical criteria based on parameters such as valence electron concentration and atomic size mismatch, as well as thermodynamic calculations such as the calculated phase diagram (CALPHAD) method. It then summarizes the characteristics and hydrogen storage performance of the reported alloys, with a detailed discussion of their phase compositions, microstructures, and the corresponding effects on hydrogen storage properties. Particular emphasis is placed on the critical roles of phase boundaries, multiphase synergy, and specific microstructural features (e.g., networked/eutectic morphologies) in enhancing activation performance and improving hydrogen diffusion kinetics. Although the current hydrogen storage capacity of HEIs (approximately 1 H/M (hydrogen-to-metal atomic ratio)) remains lower than that of body-centered cubic (BCC)-structured HEAs, their exceptional reversible hydrogen absorption/desorption capability at room temperature, lack of activation requirements, and remarkable cycling stability make them highly promising for applications in which a moderate capacity is sufficient, such as mobile hydrogen storage. This review provides a systematic summary of research progress on HEIs for hydrogen storage, focusing on the effects of alloy design strategies, phase composition, and microstructural regulation on hydrogen storage properties. The primary challenge currently facing HEIs is their relatively low hydrogen storage capacity. Accordingly, this paper outlines future development directions to address this issue. This review provides a theoretical basis and guidance for the development of next-generation high-performance hydrogen storage materials.

First-principles density functional theory (DFT) calculations are employed to investigate the structural, optoelectronic, mechanical, thermodynamic, and hydrogen storage properties of XCsSiH₆ (X = K, Rb). The hydrogen atoms form discrete SiH₆ octahedra stabilized by alkali metal cations, confirming a stable cubic $F\overline 4 3m$ symmetry upon structural optimization. Both compounds exhibit both thermal and dynamical stability. The calculated gravimetric hydrogen storage capacities are 2.94wt% for KCsSiH₆ and 2.40wt% for RbCsSiH₆. Electronic band structure analysis indicates indirect band gaps of 3.14 eV (KCsSiH₆) and 3.17 eV (RbCsSiH₆), with hydrogen contributing mainly to the valence band maximum (VBM) and Cs/Rb/K atoms to the conduction band minimum (CBM). Optical property analyses of the dielectric response, absorption, and reflectivity show pronounced ultraviolet activity, suggesting suitability for optoelectronic and UV-filtering applications. Both hydrides are found to be brittle yet elastically isotropic, with KCsSiH₆ being slightly less stiff than RbCsSiH6. Comprehensive thermodynamic analysis demonstrates favorable variations in entropy, heat capacity, and Gibbs free energy up to 800 K, indicating the pronounced thermal stability of the investigated systems. Overall, XCsSiH₆ hydrides appear to be stable semiconductors with moderate hydrogen storage capacity and desirable optical properties, suitable for various energy and electronic applications.

Lithium-rich layered oxides are prospective materials for future-generation cathodes attributable to their high specific capacity. However, significant surface instability, particularly under high-voltage operating conditions, leads to substantial voltage decay and dramatic capacity degradation during long-term cycling, severely limiting their widespread application. In this study, we developed a universal brine quenching strategy to construct a stabilized composite surface structure for lithium-rich layered oxides. This structure comprises an inner surface layer with a Y-doped layered structure and an outermost layer featuring a disordered rock-salt structure. Doping in the layered structure strengthens the Y–O bonds, raises the energy barrier for oxygen evolution, and significantly increases the stability of the lithium-rich layered oxide surface, suppresses structural degradation during long-term cycling, and facilitates Li⁺ diffusion kinetics. The improved redox activity, combined with superior structural stability, contributes to an outstanding electrochemical performance. For instance, the Y-quenched Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ (LLO) cathode exhibited an improved discharge capacity of 283 mAh·g⁻¹ at 0.1 C and 223 mAh·g⁻¹ at 1 C, along with remarkable cyclic stability retaining 91.2% of its capacity after 300 cycles at 1 C, and a reduced voltage decay of 0.76 mV per cycle (compared to 1.16 mV per cycle for pristine LLO). This research provides valuable insights into the design and synthesis of high-energy-density lithium-rich layered oxides through a simple and cost-effective strategy.

Co-free lithium-rich manganese-based oxides (LRMOs), which offer energy densities over 1000 Wh·kg⁻¹ and low raw material cost, are attractive cathode candidates for next generation high-energy density lithium-ion batteries (LIBs). Nonetheless, their practical application is hindered by their high initial irreversible capacity, capacity and voltage decay, and voltage hysteresis. Herein, a novel iron phosphide modification strategy is presented, where Fe₃P is incorporated into the bulk phase of the Li_1.2Ni_0.2Mn_0.6O₂ (LNMO) cathode material during its fabrication process of high-temperature calcination of the precursor after spray drying. This regulation stabilizes the crystal lattice of LNMO, promotes the formation of a robust cathode–electrolyte interphase, and mitigates decomposition of the electrolyte, thereby significantly enhancing the cycling stability and rate capability. Consequently, the modified LNMO achieves a capacity of 179 mAh·g⁻¹ (98% capacity retention) after 450 cycles at 1C (1C = 200 mA·g⁻¹), and 82% capacity retention after 1000 cycles at 5C. The regulatory strategy is facile and straightforward contributes superior electrochemical performance for LNMO cathode materials, which has potential for wide-ranging applications.

Lithium metal batteries have been widely used in energy storage applications owing to their high theoretical energy density. However, the unstable solid electrolyte interphase (SEI) in the batteries lead to the formation of lithium dendrites and “dead lithium”, thus affecting the safety and cycle life of the battery. To address this issue, an artificial SEI was prepared using a polymer coating strategy. The introduction of succinonitrile (SN) accelerates ion transport by promoting the dissociation of lithium salts. The solid electrolyte Li_6.5La₃Zr_1.5Ta_0.5O₁₂ (LLZTO) enhances the mechanical strength of artificial SEIs and promotes ion conduction. Furthermore, the competitive coordination between LLZTO and SN inhibits lithium anode corrosion, forming SEI rich in LiF and Li₃N. Therefore, the lithium metal anode modified with an artificial SEI can be stably plated/stripped for more than 10000 h. The LiFePO₄ full cell assembled with the modified anode exhibited a discharge specific capacity of 133 mAh·g⁻¹ and a capacity retention of 97% after 1000 cycles at 2 C (1 C = 170 mA·g⁻¹). Notably, the anode modified with the artificial SEI exhibited excellent electrochemical performance even at low temperatures.

Conventional graphite synthesis involves CO₂ emission and a graphitization process at a high temperature of ∼3000°C. Herein, we report a new method to synthesize high-performance graphite anode materials from greenhouse CO₂ gas at an external heating temperature as low as 135°C. Transition metal catalysts are not required for low-temperature synthesis of graphite. Extreme graphitization temperatures are not required as compared to graphite synthesized from petroleum coke-based materials. The graphitization degree of graphite was found to be strongly related to CO₂ pressure. Graphite was synthesized at a maximum pressure of 20 MPa, whereas semi-graphited carbon was synthesized at a maximum pressure of 6.3 MPa. The synthesized graphite exhibited superior lithium storage kinetics and excellent cycling stability over 3000 cycles, with a capacity retention of ∼100% at 1.0 A·g⁻¹. This work establishes an integrated sustainable strategy that concurrently addresses greenhouse gas utilization and energy-efficient anode material production.

The rapid development of the mobile communication and electric vehicle markets is driving a growing demand for next-generation lithium-ion battery (LIB) technology. Key electrochemical properties of LIBs, including energy density, rate performance, and cycling stability, are largely determined by the performance of the anode material. High-entropy oxides (HEOs), with unique multi-component systems and entropy-stabilized frameworks, exhibit tailorable physicochemical properties and outstanding structural stability, making them promising candidate anode materials for next-generation LIBs. Among these systems, Fe-containing HEOs (Fe-HEOs) exhibit abundant iron sites, low production costs, and impressive electrochemical activity. Additionally, the incorporation of Fe with other metallic elements can effectively increase the energy-storage capacity and lifespan of LIBs. This review systematically summarizes the latest advancements in Fe-HEOs as anode materials for LIBs. The discussion centers on the rational design principles, synthetic strategies (solid-state, liquid-phase, and gas-phase routes), and performance optimization mechanisms for Fe-HEOs. In addition, the vital roles of advanced characterization techniques in elucidating the composition and structure of Fe-HEOs, and providing mechanistic insights to promote electrochemical property improvements, are discussed. Finally, the current bottlenecks and prospective research directions are analyzed to provide theoretical guidance and practical references for the design of high-performance, low-cost Fe-HEO anode materials.

Conventional hard carbon anodes, despite their high sodium storage capacity, suffer from two major limitations: sluggish ion diffusion kinetics due to tortuous micropore networks and significant volume expansion arising from disordered carbon structures. These inherent defects collectively compromise rate capability and cycling stability. Herein, we devise a graphene oxide (GO)-directed templating approach to architect zeolitic imidazolate framework (ZIF)-derived carbon into a hierarchical nanoflower superstructure with radially aligned meso/macroporous nanosheets. This superstructure integrates three synergistic features: three-dimensional interconnected channels and graphitic domains enabling fast ion/electron transport, radially aligned nanosheets maximizing electrode–electrolyte contact while accommodating volume expansion, and nitrogen-doped defect sites providing preferential redox-active centers for sodium storage. The optimized ZIF-9@GO-6 achieves a high specific capacity of 521.8 mAh·g⁻¹ at 0.05 A·g⁻¹ with an initial Coulombic efficiency of 89.2%, and retains a specific capacity of 298.2 mAh·g⁻¹ after 500 cycles. This GO-directed morphological engineering strategy effectively resolves the intrinsic trade-offs between porosity, conductivity, and structural stability in conventional hard carbon anodes, paving the way for scalable, high-performance sodium-ion batteries.

Biomass-based hard carbon is considered a highly promising anode for sodium-ion batteries. Nevertheless, its practical deployment is often impeded by excessive specific surface area and an abundance of structural defects, which inevitably lead to limited initial coulombic efficiency and unsatisfactory sodium storage capacity. Herein, we report a pepper stalk-derived hard carbon engineered via temperature-mediated closed-pore tuning, delivering a reversible capacity of 302.3 mAh·g⁻¹ (initial coulombic efficiency of 86.7%) and remarkable cycling stability (87.6% capacity retention after 300 cycles). Systematic characterization reveals that carbonization at 1600°C optimally develops 3.48 nm closed pores and enhances graphite domains, achieving a high plateau capacity of 191.7 mAh·g⁻¹, which constitutes 63.4% of the total capacity attributed to efficient Na⁺ ion filling. A full cell paired with a Na₃V₂(PO₄)₃ cathode achieves an energy density of 271.0 Wh·kg⁻¹ based on the total mass of the active materials. This research provides a viable and industrial-scale methodology for pore-structure engineering, overcoming major hurdles to the market adoption of biomass-derived carbon materials.

This study presents a multi-scale modeling framework to describe the mechanical behavior of a 0.1 mm-thick commercially pure titanium (CP-Ti) sheet developed for fuel cell bipolar plates. Since standardized methods for characterizing ultra-thin sheets under complex stress states are lacking, a virtual modeling approach was employed. At the grain scale, a crystal plasticity finite element (CPFE) model was constructed to incorporate the relevant slip and twinning systems, enabling prediction of responses under diverse loading conditions. Extending to the continuum scale, the CPFE results, combined with tensile data, were used to calibrate an advanced constitutive model based on the evolutionary Yld2000-2d yield function, capable of capturing anisotropic behavior. Validation against independent limiting dome height tests confirmed the predictive accuracy of the framework. The proposed approach provides a basis for simulating the forming behavior of ultra-thin CP-Ti sheets and supports precise manufacturing of bipolar plates in fuel cell systems.

Indium-based materials have emerged as promising alternative catalysts for the selective electroreduction of CO₂ to formate, yet the optimal catalytic configuration remains elusive. Herein, theoretical calculation reveals that metallic indium over oxygen vacancy-containing In₂O₃ support (In/In₂O₃-V_O) possesses the lowest energy barriers (0.99 eV) for CO₂ reduction to formate. A rational air-annealing strategy applied to In³⁺-adsorbed resin is developed to synthesize indium oxide catalysts containing oxygen vacancy (R-In₂O₃). In-situ spectroscopy techniques confirm in-situ electrochemical reconstruction of the In/In₂O₃ configuration and the effective stabilization of the key reaction intermediate (HCOO*). Consequently, the catalyst delivers excellent CO₂-to-formate conversion performance, maintaining a current efficiency above 92% over 56 h of galvanostatic electrolysis at −250 mA·cm⁻². These insights provide an effective strategy for the rational design of high-performance and durable indium-based electrocatalysts for sustainable formate production.

Asymmetric supercapacitors (ASCs) are promising candidates for high-power output applications; however, their theoretical capacity remains largely unrealized owing to the low specific capacity of carbon negative electrodes. Traditional strategies for enhancing the specific capacity of carbon via structural optimization often compromise the tap density, electrical conductivity, and rate performance of the material. In this study, we address this bottleneck by incorporating 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxyl (4OT) as a redox mediator into the electrolyte to construct ASCs with well-matched capacities and potential windows between the two electrodes. With 50, 100, and 200 mM 4OT added in electrolytes, the activated carbon electrodes achieve specific capacities of 113, 181, and 263 mAh·g⁻¹ at 2 A·g⁻¹. The Ni₃S₂/CoNi₂S₄ positive electrode exhibited a specific capacity of 415 mAh·g⁻¹, benefiting from its superior electrical conductivity, abundant active sites, and enhanced electrochemical activity. Notably, introducing 4OT to the electrolyte effectively balances the capacity and potential window of the two electrodes. Consequently, the as-assembled ASCs deliver a maximum energy density of 55 Wh·kg⁻¹, which surpasses previously reported values. Our work demonstrates that the rational selection and application of redox mediators have great potential for balancing electrode capacity and boosting the energy density of high-performance ASCs.

Amidst escalating global energy demands and the environmental constraints of conventional fossil fuels, hydrogen energy has emerged as a pivotal zero-emission energy carrier. The four-electron oxygen evolution reaction (OER) exhibits slower kinetics compared to the two-electron hydrogen evolution reaction (HER), constitutes the limiting process in electrolytic hydrogen production, with two principal mechanisms currently understood to govern its kinetics: the adsorbate evolution mechanism (AEM), which typically exhibits high stability but relatively low activity in its conventional framework, and the lattice oxygen oxidation mechanism (LOM), which generally shows high activity but insufficient stability in pristine systems. Notably, recent advances in catalyst engineering have enabled the development of modified AEM/LOM-based catalysts that balance stability and activity. Recent mechanistic developments have broadened this paradigm with proposed oxide pathway mechanisms (OPM) and coupled oxygen evolution mechanisms (COM), which incorporate innovative concepts such as dynamic surface reconstruction and concerted proton–electron transfer processes. This review firstly reviews the OER mechanisms, including AEM, LOM, OPM, and COM, followed by a systematic enumeration of identification strategies based on the core features of each mechanism, including kinetic features, experimental features, and theoretical calculations. Finally, we further highlight emerging opportunities in mechanism-directed material innovation, offering actionable insights for next-generation sustainable energy technologies.

The development of highly active and stable electrocatalysts for the oxygen reduction reaction (ORR) remains a challenging task for improving the efficiency of fuel cells. Although Pt and Pt–transition metal alloy-based catalysts stand out as practical choices, they suffer from poor Pt utilization and stability. In this regard, highly electrically conducting, purely metallic, hierarchical 3D-porous, and nanowire aerogels as self-supported electrocatalysts have gained interest in recent decades. Metal aerogels are regarded as efficient catalytic materials, especially for electrocatalysis, as they integrate the unique features of both metallic and porous aerogels. In this review, we provide an overview of the recent progress in metal aerogel catalysts for ORR. Metal aerogel catalysts exhibit excellent ORR activity due to their high intrinsic activity arising from excellent Pt utilization and the exposure of active sites due to their metallic nature. Owing to their high Pt utilization, several noble metal aerogel catalysts were found to exhibit higher mass activity than traditional Pt/C catalysts and a mass activity target of 440 A per g Pt at 0.9 V vs. RHE, suggesting the high potential of metal aerogels as ORR catalysts in fuel cells. Herein, we summarize the recent benchmark research outcomes of metal aerogel catalysts for the ORR, their effects on the microstructure of catalyst layers, fuel cell performance, and cutting-edge modifications of recently reported metal aerogel catalysts. We systematically review the various aspects of metal aerogel catalyst synthesis, their advantages over traditional Pt/C catalysts, and ORR kinetics, and provide future research directions and recommendations to further improve and integrate metal aerogel catalysts into realistic fuel cells.