Antimony sulfide (Sb2S3) is a promising light-absorbing semiconductor for photovoltaic applications and exhibits significant potential for photoelectrochemical water splitting. In this study, Sb2S3 was prepared by sulfurizing electrodeposited Sb at 250°C, followed by the deposition of Sb2O3 through a chemical bath method. To further enhance the heterojunction, Fe3+-modified Sb2S3/Sb2O3 was obtained by treating the junction with varying concentrations of FeCl3 solution. X-ray diffraction and X-ray photoelectron spectroscopy analyses confirmed the successful formation of the Sb2S3/Sb2O3 heterojunction. The optimal FeCl3 concentration for modification was found to be 0.05 M, which reduced the lattice mismatch between Sb2S3 and Sb2O3, while improving the alignment of their energy bands. The photocurrent density of the Sb2S3/0.05Fe3+/Sb2O3 heterojunction at −0.15 V (vs. RHE) was −0.093 mA/cm2, approximately 1.72 times higher than that of the Sb2S3/Sb2O3 heterojunction and 2.33 times higher than the monolithic Sb2S3 film. This improvement is attributed to enhanced charge separation and charge transfer efficiencies. Overall, the study demonstrates the successful modification of the Sb2S3/Sb2O3 heterojunction, optimizing the lattice mismatch, energy band alignment, and heterojunction interface, ultimately leading to a low-cost photoelectrode material with high light energy utilization efficiency.

In this study, AgCuCe/C catalysts were synthesized via vacuum ion-beam sputtering followed by electrochemical dealloying. The catalysts were comprehensively characterized using x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), x-ray photoelectron spectroscopy (XPS), gas chromatography (GC), and electrochemical measurements. We systematically investigated how the optimized surface morphology, phase composition, and elemental valence states affect the CO2 electroreduction performance and the distribution of gaseous products. Electrochemical dealloying promoted the leaching of a portion of Cu from the catalyst surface, forming Ag-Cu and Ag-Cu2O heterointerfaces, thereby exposing abundant active sites for CO2 adsorption and reaction. Notably, dealloying in an HCl + FeCl3 electrolyte resulted in a refined and uniformly distributed nanocube architecture on the catalyst surface. This morphology further modulates the electronic structure at the Ag-Cu and Ag-Cu2O interfaces, facilitating electron transfer from Cu to Ag and enhancing surface CO2 adsorption. Under an applied potential of − 0.6 V versus RHE, the Faradaic efficiencies for CO and CH4 increased by 188.8

In response to crude tin containing high levels of hazardous waste, this study proposes the use of vacuum metallurgy to eliminate Pb, Sb, and As impurities in tin by leveraging the difference in vapor pressure to prevent secondary contamination of these hazardous waste elements. Theoretical calculations of vapor pressure, separation coefficients, and phase diagrams were followed by lab and industrial trials. Lab tests determined optimal conditions: vacuum <= 10 Pa, temperature 1550K, holding time 180 min. Under these conditions, residual Sb (0.00023 %) and Pb (0.0018 %) met China's GB/T 728-2020 Sn99.95 AA tin standard. Industrial trials used a multi-stage continuous vacuum furnace with an As condensation system. Results showed vacuum distillation effectively produced 3N-grade refined tin (Pb, Sb, As compliant), a Sn-Pb-Sb alloy (similar to 1 % Sn), and a crude As alloy (similar to 85 % As). The Sn direct yield reached 92.72 % and increased by 6.15 %. The traditional aluminum addition and antimony removal and crystallization lead removal processes have been eliminated, eliminating hazardous wastes such as aluminum-arsenic slag and copper slag, offering significant simpler equipment and environmental benefits. This study provides novel green refining technology for crude tin, supporting sustainable development in tin metallurgy.

Low reduction efficiency is a critical issue that limits the advancement of the magnesium vacuum carbothermal reduction smelting process. This investigation introduces a novel magnesium smelting process that substitutes magnesium fluoride (MgF2 ) for calcium fluoride (CaF2 ) as a catalyst in the vacuum carbothermal reduction of magnesium. The viability and optimal operating conditions of the new method were assessed through thermodynamic calculations of Gibbs free energy in the MgO-C-MgF2 system. Additionally, the catalytic effects of MgF2 on the reduction of MgO were examined under different holding times in vacuum conditions. Analytical results indicated a significant improvement in the reduction efficiency of MgO upon the incorporation of MgF2 . MgF2 serves a catalytic function in the reduction process. When F- acts, it elevates the relative concentration of Mg in the reduction system and promotes the reduction reaction. Improvements in reduction efficiency are observed as the holding period duration increases and with higher concentrations of MgF2 . However, the improvement in reduction efficiency tends to plateau when the concentration exceeds 7 %. The resulting magnesium condensate exhibits a robust crystalline structure, with a purity of 79.39 %. The crystallization outcomes are influenced by the degree of reverse reactions. Compared to CaF2 , MgF2 offers significant economic, environmental, and catalytic advantages. This process supports the goals of sustainable, green development and aligns with clean production standards in the magnesium metallurgy sector. (c) 2026 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

In the realm of electrochemical energy storage, it is vital to design electrode materials that are both highperformance and stable cycling. Compositing with carbon material is an effective method for addressing the volume expansion of silicon-based negative electrodes, with the uniformity and dependability of the composite material structure design dictating its electrochemical performance. We offer a simple and scalable electrostatic self-assembly approach for constructing cations and anions prone to in situ electrostatic interactions adsorbed onto Si nanoparticles and lignin (Si/C-lignin@C-SE), which is generated by carbon sintering the lignin@C onto Si. Unlike ball milling and hydrothermal methods, Si/C-lignin@C-SE exhibits homogeneous carbon layer (3-6 nm) with high specific surface area and graphitization degree, resulting in abundant binding sites for nano-silicon particles. This unique structure can offer stability and limit the influence of Si nanoparticle volume expansion, as well as significantly increase electronic conductivity and electrochemical activity. Compared to the traditional mechanical ball milling method, Si/C-lignin@C-SE composite shows excellent specific capacity and ultrastable long-cycling performance: an initial discharge capacity of 2593.19 mAh g-1 with coulombic efficiency of 92.3 %, and stable capacity of 1200 mAh g-1 after 200 cycles. As a result, as-prepared Si/C-lignin@C-SE electrodes are expected to achieve good electrochemical performance and long-term durability.

ABSTRACT Crystal water, traditionally viewed as a passive or even detrimental component, has emerged as an integral and dynamic structural unit in advanced energy storage materials. Despite its critical role in modulating structural stability and ion transport kinetics, a comprehensive understanding of the distinct structure‐property dynamics of crystal water across diverse energy storage systems remains elusive. Herein, this review systematically decodes the fundamental mechanisms and multifaceted applications of crystal water engineering. We comprehensively examine its tailored functionalities in monovalent‐ion (e.g., Li + , Na + , K + ) and multivalent‐ion (e.g., Mg 2+ , Zn 2+ , Ca 2+ ) batteries, highlighting distinct mechanistic disparities ranging from mitigating steric hindrance via lattice expansion to shielding electrostatic interactions through solid‐state solvation. The discussion also extends to emerging systems, such as supercapacitors and solid‐state or quasi‐solid‐state electrolytes, where structurally confined water uniquely acts as an ionic lubricant and a rapid ion‐hopping promoter. Finally, critical open questions and emerging opportunities are analyzed, highlighting transformative potential of crystal water in guiding the rational design of next‐generation energy storage materials.

Arsenic (As), commonly present in sulfides, oxides, and metal compounds like copper, cobalt, nickel, and lead, poses significant environmental and health hazards. Effective arsenic waste management is essential for pollution control and resource recovery. While vacuum distillation and graded condensation have been studied individually, this study introduces an integrated approach that combines single-step vacuum distillation with a multistage fractional condensation system based on molecular mean free path (MFP) principles. This method enables simultaneous recovery of elemental arsenic and enrichment of lead (Pb), bismuth (Bi), and silver (Ag) from highly toxic waste. By aligning condenser spacing with arsenic's MFP, the system enhances selective volatilization, differing from earlier empirical or single-stage designs. The approach was validated through theoretical analysis, CFD simulations, and experiments. At 500 degrees C and 10 Pa for 60 min, it achieved 99.1 % pure crude arsenic recovery, increased lead content from 37.55 % to 72.2 %, and reached 97.82 % arsenic removal efficiency. CFD results revealed detailed temperature and vapor flow patterns, closely matching experimental outcomes and confirming effectiveness. This clean, one-step process provides an economically feasible solution for arsenic removal and valuable metal concentration, with potential applicability to other complex waste streams.

Titanium-aluminum alloys are highly reactive at elevated temperatures and readily react with crucible materials during smelting, leading to degraded performance. Therefore, it is essential to identify appropriate crucibles for melting titanium-aluminum alloys. Nb is a beta-stabilising element and high-melting-point metal, making it a potential crucible material. In this study, the high-temperature wetting behaviour of Ti48Al (at.%) on Nb was investigated. The presence of Nb-based solid solution and ternary Nb-TiAl intermetallic compounds in the bonding region indirectly altered wettability. The results obtained from kinetics analysis indicated that early stage spreading strictly complied with the reaction product controlled model. In the subsequent stages, the wetting dynamics were dominated by the outward migration of the precursor film. Intermetallic compounds formed by interfacial reactions influenced wettability. A thin film surrounding the melt was identified. The forward movement of the precursor film is driven by interfacial reactions dominated by active aluminium. Furthermore, intermetallic compounds within the region could effectively alter the migration of the triple line. The wetting behaviour of the TiAl/Nb system during high-temperature processes was elucidated. The findings of this study offer new theoretical support for Nb as a crucible material. Les alliages titane-aluminium sont tr & egrave;s r & eacute;actifs & agrave; haute temp & eacute;rature et r & eacute;agissent facilement avec les mat & eacute;riaux des creusets lors de la fusion, entra & icirc;nant une d & eacute;gradation de leurs performances. Par cons & eacute;quent, il est essentiel d'identifier des creusets appropri & eacute;s & agrave; la fusion des alliages titane-aluminium. Nb est un & eacute;l & eacute;ment stabilisateur beta et un m & eacute;tal & agrave; point the fusion & eacute;lev & eacute;, ce qui en fait un mat & eacute;riau de creusets potentiel. Dans cette & eacute;tude, on a examin & eacute; le comportement de mouillage & agrave; haute temp & eacute;rature de Ti48Al (% at.) sur le Nb. La pr & eacute;sence d'une solution solide & agrave; base de Nb et de compos & eacute;s interm & eacute;talliques ternaires Nb-TiAl dans la r & eacute;gion de liaison a indirectement modifi & eacute; la mouillabilit & eacute;. Les r & eacute;sultats de l'analyse cin & eacute;tique ont indiqu & eacute; que l'& eacute;talement initial suivait strictement le mod & egrave;le contr & ocirc;l & eacute; par le produit de r & eacute;action. Dans les & eacute;tapes suivantes, la dynamique de mouillage & eacute;tait domin & eacute;e par la migration vers l'ext & eacute;rieur du film pr & eacute;curseur. Les compos & eacute;s interm & eacute;talliques form & eacute;s par les r & eacute;actions interfaciales ont influenc & eacute; la mouillabilit & eacute;. On a identifi & eacute; un film mince entourant le bain de fusion. La progression du film pr & eacute;curseur est men & eacute;e par les r & eacute;actions interfaciales domin & eacute;es par l'aluminium actif. De plus, les compos & eacute;s interm & eacute;talliques dans la r & eacute;gion pourraient modifier efficacement la migration de la ligne triple. On a & eacute;lucid & eacute; le comportement de mouillage du syst & egrave;me TiAl/Nb lors de proc & eacute;d & eacute;s & agrave; haute temp & eacute;rature. Les r & eacute;sultats de cette & eacute;tude proposent de nouveaux supports th & eacute;oriques & agrave; l'utilisation du Nb comme mat & eacute;riau de creuset.

Tellurium is a strategically critical metal, which is mainly derived from copper-tellurium slag a key intermediate generated during tellurium extraction from copper anode slime - and is present predominantly as Cu2Te. Given the high stability and limited separability of the Cu-Te system, conventional recovery technologies generally suffer from lengthy process flows, dispersed metal losses, and significant environmental burdens. Herein, a novel short-flow process is proposed for the simultaneous separation and recovery of copper and tellurium from Cu2Te via electrodeposition using a deep eutectic solvent (DES) composed of choline chloride (ChCl) and urea. The effects of scan rate and temperature on the electrochemical behaviors of copper and tellurium in the ChCl-urea DES were systematically investigated via cyclic voltammetry. The influences of key parameters (dissolution time, temperature, and particle size) on the solubility of Cu2Te in DES were examined, and the rate-limiting step of the dissolution process was determined through comparative kinetic fitting. Under optimized electrolysis conditions of-0.7 V, 70 degrees C, and 12 h, copper particles with sizes ranging from 0.5 to 1.5 mu m were deposited at the cathode, while elemental tellurium was generated at the anode. Mechanistic analysis reveals that copper exists in DES as [CuCl2]-, which undergoes dissociation to Cu+ prior to cathodic reduction, whereas tellurium exists solely as Te2-.This approach provides a short, environmentally friendly route for recovering copper and tellurium from copper-tellurium slag. This study is based on high-purity Cu2Te as a model system; the influence of typical impurities (e.g., Ag, Se) in real residues remains to be further investigated in future work.

To address the issues of SO2 pollution, high energy consumption, long process flow, and severe carbon emissions in the conventional volatilization smelting process for sulfur-oxygen mixed antimony ore, this study proposes a novel carbon-free direct reduction process based on a B2O3-Al2O3-CaO-SiO2 quaternary low-melting-point slag system for low-temperature electric furnace smelting. This process utilizes the interactive reaction between Sb2S3 and Sb2O3 (Sb2S3 + 2Sb2O3 = 6Sb + 3SO2) to achieve one-step reduction of antimony through a self-reduction mechanism without consuming any carbon-based reductant, eliminating carbon emissions at the source, with the product mainly consisting of antimony matte (containing metallic antimony and Sb2S3). Thermodynamic analysis indicates that this reaction can occur spontaneously in the molten phase, and experiments confirm that it can also occur in the gas phase. By investigating the effects of slag basicity, smelting temperature, and holding time on the direct recovery rate of antimony, the optimal process parameters were determined as follows: basicity of 0.5, temperature of 1100°C, and holding time of 1 h. Under these conditions, the direct recovery rate of antimony reaches 93.95%, the mass fraction of metallic antimony in the antimony matte is 56.6 wt%, and the slag ratio is approximately 48%. Compared with conventional processes, this novel process significantly shortens the process flow, generates high-concentration SO2 that can be used for sulfuric acid production (enabling sulfur resource utilization), and substantially reduces slag generation. This work provides a new technological pathway for the carbon-free, clean, and efficient utilization of complex antimony resources.

Low-grade cassiterite-wolframite-scheelite mixed ore is a complex mineral resource that presents significant challenges in terms of processing. Recovering tin (Sn) from the mixed ore not only promotes the efficient utilization and sustainable development of Sn resources, but also reduces the cost and wastewater discharge of tungsten (W) metallurgy. This paper proposes a green method for one-step vacuum treatment to separate and recover Sn from low-grade cassiterite-wolframite-scheelite. Thermodynamic calculations indicate that cassiterite (SnO2) can react at high temperatures with sulfur vapor and FeS generated from the decomposition of the sulfiding agent pyrite(FeS2), forming the volatile compound stannous sulfide(SnS). The effects of various factors, including the type of sulfiding agent, the sulfiding agent addition ratio, the holding temperature, and the holding time, were investigated through experimental research. Under the optimal experimental conditions, the Sn content in residue decreased from 20.84 wt% in the raw material to 0.037 wt%, with a Sn volatilization rate and recovery rate of 99.83% and 98.61%, respectively. This achieved highly efficient separation and recovery of Sn from the mixed ore, while significantly reducing the Sn content in the mixed ore, thereby creating ideal conditions for the further smelting and resource recovery of wolframite and scheelite. This method provides guidance for the separation and recovery of Sn from low-grade cassiterite-wolframite-scheelite.

High-performance Gd-containing Mg alloys are widely used in aerospace and high-temperature applications, yet conventional recycling processes suffer from significant rare earth loss and low recovery rate, seriously hindering the circular utilization of Mg and strategically valuable Gd. To address this challenge, vacuum gasification technology was employed for the synergistic recovery of Mg and Gd from such scrap, integrating thermodynamic calculations, phase diagram analysis, phase evolution investigations of the Mg-Gd system, and validation experiments on JDM4 alloy scrap. The results demonstrate that vacuum gasification enables effective Mg-Gd separation, with reduced system pressure significantly lowering the required process temperature. Both theoretical and experimental results confirm a consistent phase evolution sequence during separation: Mg₅Gd → Mg₃Gd → Mg₂Gd → MgGd → Gd. During gasification, the Mg-Gd intermetallic compounds exist in a molten state and form a Gd-rich multilayer encapsulated structure, with Gd content increasing from the inside out. This structure inhibits Mg volatilization and induces splashing, leading to Gd loss. Reasonable regulation of the temperature and holding time, the decomposition progression and the state of these encapsulation layers can be effectively managed. Vacuum gasification of JDM4 scrap yielded condensed Mg with a purity of 99.945 wt.% and a Gd product with 93.71 wt.% purity, at recovery rates of 96.61% and 99.91%, respectively. This study provides robust theoretical and practical support for the efficient recycling of Gd-containing magnesium alloys, offering key technical guidance for promoting the sustainable circular economy of Mg and rare earth resources.

The volatilization characteristics and kinetic mechanisms of arsenic were investigated in the temperature range of 623-773 K and pressure ranges of 10-10000 Pa. The experimental results reveal that the evaporation rate increases with increasing temperature and decreasing pressure. Surface reaction control dominates at low pressures (<100 Pa), whereas diffusion control dominates at high pressures (>5000 Pa). The evaporation behavior is successfully described by an Arrhenius-type model for temperature dependence and Logistic model for pressure dependence. Key kinetic parameters, including the critical pressure, maximum evaporation rate and evaporation coefficient, were calculated. The evaporation coefficient varies between 0.010 and 0.223, and the critical pressures vary between 281 and 478 Pa with temperature.

This study presented a novel method for removing calcium (Ca) and magnesium (Mg) impurities from metallic lithium (Li), offering a transformative improvement over traditional Li salt purification processes. The Li-Ca-Mg ternary phase diagram was calculated using FactSage, revealing that at 873 K, all components formed molten alloy solid solutions. The separation coefficient (beta), calculated using the M-MIVM model, ranged from 1 to 10. However, vapor-liquid equilibrium calculations indicated that vacuum-based liquid-gas separation of the Li-Ca and Li-Mg systems was difficult to achieve. Theoretical volatilization and condensation temperatures for Li, Ca, and Mg were determined, with corresponding saturated vapor pressures at 801.16 K, 853.11 K, and 659.49 K, and condensation points at 801.24 K, 874.88 K, and 702.22 K, respectively. These findings suggested that the separation of Li, Ca, and Mg was effectively achieved through vaporization-directional condensation methods. Experiments with pure Li, Ca, and Mg demonstrated effective separation at 848 K over 120 min, yielding a Li volatilization rate of 97.1 % and impurity removal efficiencies of 96.09 % for Mg and 98.51 % for Ca. Further tests with 99.98 % high-purity Li under the same conditions revealed that in the second-level condensation zone (2-HFW) zone, Ca and Mg contents were reduced to 0.00027 % and 0.00041 %, respectively, meeting the Chinese national standard for Li-1 grade purity. Economic and environmental analyses indicate that, compared to traditional chemical purification methods, this approach demonstrates significant advantages in economic efficiency. The cost of this method is only approximately & YEN;29,000, while the two-step precipitation method costs & YEN;33,605 and the aluminum salt precipitation method costs & YEN;50,896.3. Furthermore, the process generates no wastewater or exhaust gases, highlighting its environmental sustainability. This innovative method provides an eco-friendly and economically efficient pathway for the purification of Li metal.

Silver-cadmium oxide electrical contact materials constitute a high-value yet hazardous waste stream from recycling electrical components. Conventional recycling methods, such as acid leaching-electrolysis and high-temperature reduction-volatilization, generate significant amounts of waste acid, exhaust gases, and solid residues. To mitigate this environmental burden, the study developed a novel process that separates constituent metals from complex alloy oxides by leveraging differences in their physical properties, combining theoretical and experimental approaches. The proposed method employs vacuum gasification and directed condensation. Thermodynamic calculations of the system's Gibbs free energy, maximum evaporation rate, and condensation behavior were performed. The results indicate that cadmium oxide is stable under high-temperature atmospheric pressure but decomposes significantly at 1129 K under a system pressure of 5 Pa. At 1273 K, the evaporation rate of cadmium is approximately 18,889 times greater than that of silver, and their distinct condensation temperature ranges provide a theoretical basis for efficient separation. Experimental results from the vacuum gasification and multi-stage condensation process confirm its efficacy. The silver mass fraction in the residue consistently exceeded 99.99% with a direct recovery rate above 95%. The condensed cadmium product achieved a purity over 99.99%, a direct recovery rate of up to 98.27%, and a separation rate exceeding 99.99%. A small amount of crude silver was recovered as an intermediate condensate. This process successfully achieves complete separation of silver and cadmium. Compared to conventional methods, it significantly reduces environmental impact and economic costs, demonstrating strong potential for industrial application.

This study systematically investigates the volatilization behavior of stannous sulfide (SnS) under vacuum conditions using a vacuum differential thermogravimetric furnace. The actual evaporation rates were measured over a temperature range of 700-850 degrees C and a system pressure range of 10-500 Pa. Results indicate that the evaporation rate increases significantly with rising temperature and decreasing pressure. Under constant pressure conditions, a clear linear relationship was observed between the logarithm of the evaporation rate (ln omega) and the reciprocal of absolute temperature (1/T), consistent with thermally activated evaporation kinetics. Moreover, the nonlinear correlation between evaporation rate and system pressure was accurately characterized by a logistic model, enabling the determination of the critical pressure (pcrit) corresponding to maximum evaporation efficiency at each temperature. The critical pressure exhibits a strong temperature dependence, described by the equation lg pcrit = -3504 & times;(1/T) +5.49, which reflects the thermodynamic balance between vaporization and mass transport limitations in the vacuum environment. These findings not only clarify the intrinsic volatilization mechanisms of SnS but also provide essential theoretical foundations and practical parameters for optimizing its industrial-scale vacuum thermal evaporation processing.

The widespread adoption of proton exchange membrane fuel cells (PEMFCs) is hindered by the excessive use of Pt electrocatalyst and its deficient durability. Herein, a robust integrated catalyst layer (CL) for ultra-low Pt loading PEMFCs was constructed by depositing Pt onto arc-discharge synthesized TiN nanoparticles decorated graphene (Pt/TiN@G) film. The highly graphitic and porous TiN@G as the building framework for CL not only provides efficient mass transport channels and corrosion-resistant sites to stabilize highly dispersed Pt nanoparticles via atomic layer deposition, but also endows Pt with a rich-electron state via strong electronic metal-support interactions through Pt (5dz2)/Ti (3dz2) orbital hybridization, enabling high performance PEMFC with exceptional durability at ultra-low Pt loadings. The CL as the cathode with a Pt loading of 0.05 mgPt cm-2 achieves a peak power density of 0.91Wcm-2 with a mass activity of 0.64A mgPt-1 at 0.9V, which is significantly higher than that of commercial Pt/C with 0.20 mgPt cm-2 (0.77Wcm-2, 0.13A mgPt-1) and exhibits a durability surpassing the 2025 target ( U.S. Department of Energy) with the voltage losses of 23mV at 1.5Acm-2 and 25mV at 0.8Acm-2 after 5,000 cycles (1.0-1.5V) and 30,000 cycles (0.60-0.95V) respectively. Meanwhile, the CL with 0.02 mgPt cm-2 as the anode demonstrates a 19-fold enhancement in the cell reversal tolerance compared to commercial Pt/C with 0.20 mgPt cm-2. This dual promotional effect of TiN on Pt for simultaneously improving the durability of both anode and cathode at ultra-low Pt loading offers new insights for advancing the achievement of affordable PEMFCs.

Amid the continuing rise in global demand for magnesium metal, the considerable reserves of magnesium within magnesium slag remain insufficiently recovered, resulting in notable resource wastage and increased vulnerability to supply chain instability. Current mainstream approaches for the comprehensive utilization of magnesium slag have yet to demonstrate feasibility for large-scale industrial deployment. In this work, a novel synergistic activation approach—vacuum carbothermal reduction coupled with CaF2 catalysis—is proposed. This method enables precise regulation of key parameters within the reduction system to harness the full potential of the intrinsic Ca2SiO4 phase in magnesium slag. Under high-temperature conditions, Ca2SiO4 interacts in situ with added CaF2 flux to generate a low-melting-point eutectic system, substantially reducing the reaction’s activation energy and accelerating mass transfer. These combined effects promote the efficient reduction of MgO and the highly selective liberation of Mg(g). Experiments show that this technology achieves a MgO reduction rate ≥90 % in magnesium slag, with a direct collection efficiency rate ≥85.14 %, and the purity of regenerated crystallized magnesium stabilizes at ≥88.18 %. Extending the holding time has been proven to have a dual optimization effect: first, by enhancing the catalytic efficiency of CaF2, the MgO reduction efficiency is improved by 5.51 % (when the holding time is extended by 1 h); second, it promotes uniform nucleation and equiaxed crystal growth of Mg(g) at only further increasing the purity of crystallized magnesium by +5.24 %, but it also significantly enhances its grain integrity and microstructural uniformity. This regenerated magnesium crystal, characterized by high purity and low defect density, provides an excellent microstructural foundation for subsequent plastic forming or service applications.

Coal emerges as an exceptional candidate for hard carbon precursors, attributed to its three-dimensional (3D) structure and high carbon yield. Nevertheless, abundant aromatic rings in coal tend to form a highly ordered graphitic structure after high-temperature carbonization, which hinders sodium-ion (Na+) storage. Herein, glow discharge plasma is employed to effectively introduce oxygen-containing groups into coal effectively, facilitating the formation of a cross-linked structure, which is subsequently subjected to high-temperature carbonization to obtain structurally optimized coal-based hard carbon (HC). Compared with the traditional pre-oxidation method, the surface chemical composition and microstructure of coal-based HC (OCHC20) obtained after carbonized are effectively modified by oxygen plasma treatment. The OCHC20 exhibits a remarkable initial Coulombic efficiency (ICE) of 89.3% and a reversible capacity of 302 mAh g- 1 at 0.05 A g-1, which is higher than the 263 mAh g-1 reversible capacity of hard carbon (OCHC) prepared by traditional pre-oxidation. Particularly, OCHC20 displays superior rate performance with a capacity of 238 mAh g-1 at 5 A g-1, representing a 22.7% increase over OCHC (194 mAh g-1). This study demonstrates the potential of plasma technology in the rational design of carbon-based anodes for high-performance sodium-ion batteries (SIBs).

Aqueous sodium–air batteries (SABs) represent a highly promising type of next-generation energy storage system, combining high energy density, cost-effectiveness, and environmental sustainability. However, safety concerns and limited cycle life have impeded their commercialization. Over the past decade, significant breakthroughs in electrochemical performance, battery component design, and battery configuration have been achieved in aqueous SAB systems. To date, there has been a lack of focused attention and in-depth discussion on these systems. This review covers the concept, reaction mechanism, battery device, and key components (anode, anolyte, separator, aqueous electrolytes, and catalyst) of the latest developments in aqueous SABs in detail. Moreover, advanced strategies for enhancing the electrochemical performance of aqueous SABs are discussed. Furthermore, to indicate the direction of future aqueous SAB research, this review summarizes the challenges and prospects of this rapidly evolving field. This review can provide a reference for the design and application of electrochemical energy storage systems and for the development of new systems in this field. The progress in the reaction mechanisms, battery components, and electrochemical performance of aqueous sodium-air batteries is systematically reviewed.