ABSTRACT Symmetric aqueous batteries (SABs) that employ bipolar materials as electrodes have attracted tremendous attention due to their intrinsic safety and satisfactory capacity, while they still suffer from water‐splitting and thus a narrow voltage window. In this work, we propose a novel topochemical design of introducing an electron buffer (EB) to control the electron stream when working, which efficiently attenuates the electron flow toward the water‐splitting reactions at the voltage ends. Careful measurements confirm the sharp reduction of current density applied for water‐splitting due to the EB effect. Theoretical calculations for voltage end verify the lower surface electron density of EB‐involved electrode than that of EB‐excluded electrode, demonstrating the superiority of this EB design in suppressing charge shock for water splitting. Consequently, the charging/discharging plateau of the assembled SABs based on EB increases ∼0.16 V, as well as a high capacity of 80.7 mA h g −1 achieved, which is superior to reported state‐of‐the‐art aqueous bipolar materials. Moreover, the electrolyte loss of EB‐involved SABs reduces to only 24% of that of EB‐excluded SABs, validating suppressed water splitting by confining the electron pathway. This work provides a new thought to guide electron stream through introducing a rational buffer layer, aiming at hindering water splitting while maintaining energy storage performance.

The amalgamation of high-resolution anion photoelectron spectroscopy and quantum chemistry calculations has been proven to be a powerful approach in probing the fine structures of valence-shell electrons. However, to accurately resolve the fingerprints of the spectra for compounds containing transition-metal remains a formidable challenge because of the high density of low-lying states caused by the partially filled d- and s-orbitals. In our experiments, two adjacent peaks with a separation of 190 ± 16 cm-1 of X band were observed in the photoelectron velocity map imaging of gas-phase RhO-. The theoretical calculations, including spin-orbit effects, predicted the zero-field splitting of the spatially nondegenerate ground states of the anion (3Σ-) and its corresponding neutral molecule (4Σ-) to be 133 and 32 cm-1, respectively. Based on our theoretical calculations, we suggest that the zero-field split states (Σ41/2- and 4Σ3/2-) of RhO- coexist in the gas phase under our experimental condition, and the experimentally observed separation of the X band primarily stems from the detachment of the electron from the two spin-orbit split states of the anion to those of the neutral species. The experimental spectra were further used to determine the electron affinity of RhO (1.581 ± 0.002 eV). Accompanying harmonic vibrational frequencies ωe and anharmonic constants ωeχe of the two species are also obtained.

Few-layer hexagonal boron nitride (hBN) is a promising two-dimensional dielectric for electronic and neuromorphic devices. However, its practical deployment is often hindered by the thickness nonuniformity of as-grown samples and by defects introduced during the transfer-stacking process of assembled samples. In particular, the influence of the initial hBN quality on the final stacked-film quality remains insufficiently understood. Here, we report a wafer-scale strategy for fabricating high-quality few-layer hBN based on ultraflat single-crystal hBN (USC-hBN) monolayers. Compared with transfer-stacked hBN grown on Cu foil (rough hBN), stacked few-layer USC-hBN shows a much lower surface roughness and a drastically reduced wrinkle density, indicating superior flatness and interfacial cleanliness. Furthermore, memristors fabricated from six-layer USC-hBN exhibit clearer resistive-switching behavior and a higher ON/OFF ratio than those based on rough hBN, owing to the more uniform surface/interface. These results demonstrate that source-material flatness is a critical determinant of transfer-stacked hBN quality and device performance. This work provides an effective route toward reliable integration of high-quality two-dimensional dielectric films.

[Background]Fluoride molten salt is a key coolant and fuel carrier for thorium-based molten salt reactors(TMSR).Its microstructure directly determines the physicochemical properties at high temperatures,and ultraviolet-visible(UV-Vis)absorption spectroscopy is an effective method to detect the oxidation states and coordination environments of metal ions in molten salts.Limited by extreme conditions such as high temperature(>500℃),strong corrosion,high volatility and sensitivity to trace H2O/O2,conventional instruments are difficult to realize in-situ characterization of fluoride molten salts.[Purpose]This study aims to develop an in-situ high-temperature UV-Vis absorption spectroscopy system specifically designed for corrosive fluoride molten salts.[Methods]The core of in-situ high-temperature UV-Vis absorption spectroscopy system for corrosive fluoride molten salts was a high-temperature optical furnace with optical paths,integrated with inert atmosphere protection,high-precision temperature control,efficient thermal insulation and corrosion-resistant structure.Performance verifications for this developed spectrometer included temperature calibration,mechanical repeatability and room-temperature benchmark comparison.Using this system,experiments were conducted on FLiNaK and FLiBe molten salts,where the salts were heated to elevated temperatures under an inert atmosphere,and the spectrometer was employed to collect absorption spectra and to monitor the dynamic evolution of chromium species during the reaction process.[Results]Experimental results show that the system operates stably up to 800℃without optical window degradation or baseline drift.At 650℃,FLiNaK-CrF3 exhibits two well-resolved absorption peaks at approximately 450 nm and 700 nm,corresponding to the characteristic d-d transitions of Cr3+.FLiBe-UF4 shows a characteristic absorption spectrum consistent with literature reports.These peak positions deviate from literature values by less than±2 nm.During real-time monitoring of Cr3+in FLiBe at 650℃,the absorbance at 450 nm decreases from 1.28 to 0.39 within 120 min.[Conclusions]The developed UV-Vis absorption spectroscopy system in this study has the ability of in-situ characterization of molten salt species and redox processes in high-temperature and strong corrosion environments,providing an experimentally verified key test platform for the research of molten salt chemistry and corrosion mechanism of TMSR.

The electrocatalytic nitrate reduction reaction (NO3RR) represents a viable solution that can not only restore the global nitrogen cycle but also provide a sustainable avenue for NH3 synthesis. Herein a series of Cu-Co catalysts were designed and prepared using a tungstate group as the structural backbone. Experimental and theoretical investigations reveal that the incorporation of Co sites effectively modulates the electronic structure of Cu sites, thereby enhancing nitrate adsorption and deoxygenation. This modification also significantly lowers the energy barrier for subsequent hydrogenation by accelerating water dissociation while simultaneously suppressing the competing hydrogen evolution reaction. As expected, the optimal Cu0.85Co0.15WO4 exhibits the outstanding NO3RR performance for NH3 synthesis, achieving a high Faradaic efficiency of 91.61% and a yield rate of 48.56 mg h-1 mgcat. -1 at -0.8 V. Furthermore, a highly efficient zinc-nitrate battery was developed, accomplishing the triple objectives of NH3 synthesis, nitrate wastewater treatment, and electrical energy output.

A Fe/Zn@BC particle-enhanced electrochemical process is developed to improve diclofenac (DCF) degradation. The particle-enhanced electrochemical process caused a 4.31 times increase in the DCF removal and reduced the electricity consumption to just 0.22 times that of the conventional chemical process. Fe/Zn@BC particles functioned both as electrodes for electrochemical oxidation and as catalysts for Fenton oxidation. Systematic optimization identified the ideal operating conditions to be a Fe/Zn@BC dosage of 0.1 g/L, a neutral pH of 7, and a current density of 5 mA/cm2. These conditions balanced high efficiency with cost-effectiveness. The electron spin resonance and quenching experiments revealed that center dot OH and 1O2 were the primary reactive oxidizing species that contributed to degradation rates of 71.6 % and 17.9 %, respectively. The possible degradation mechanisms primarily included dechlorination hydroxylation, hydroxylation, decarboxylation, C-N bond cleavage, and dehydrogenation. The diclofenac degradation was virtually independent of the water matrix, indicating that Fe/Zn@BC possesses a broader application for electrochemical aquatic treatment. This work provides new insights into DCF degradation during electrochemical treatment processes.

While the intrinsic activity of single-atom catalysts (SACs) in the oxygen reduction reaction (ORR) is well-recognized, the synergistic role of co-existing metal nanoparticles has remained underexplored. Herein, we elucidate the electronic modulation effect of Cu nanoparticles (Cu NPs) on adjacent single-atom Cu sites through a combination of density functional theory (DFT) calculations and experimental validation. DFT reveals that proximal Cu NPs intensify the local electric field, strengthening Cu 3d-N 2p orbital hybridization and inducing an upshift of the Cu d-band center toward the Fermi level. This electronic modulation optimizes the binding affinity of oxygen intermediates, switching the rate-determining step from *OOH formation to *OH desorption and lowering the free-energy barrier to 0.313 eV. Guided by these theoretical insights, we synthesize a hybrid electrocatalyst (CuNP-SA/NC) via a facile immersion-calcination strategy, comprising Cu NPs dispersed on Ndoped carbon hosting atomically dispersed Cu sites. The optimal CuNP-SA/NC-60 exhibits a half-wave potential of 0.883 V vs. RHE and a limiting current density of 5.21 mA cm-2, outperforming both CuSA/NC and commercial Pt/C. When deployed in Zn-air batteries, it delivers a peak power density of 151 mW cm-2 with exceptional stability over 440 h of operation. This work establishes that metal nanoparticles can function as electronic promoters rather than mere spectators, providing a design principle for advanced ORR electrocatalysts through orbital hybridization engineering. The findings also demonstrate a successful paradigm of theory-guided catalyst design, with implications for developing high-performance materials for energy conversion applications.

The key to advancing Zn-air batteries (ZABs) and flexible Zn-air batteries (FZABs) lies in creating electrocatalysts with flexibility, porosity, high efficiency, and stability. Herein, Cu/Fe-N@PCFs is prepared by electrospinning and pyrolysis. Fe-ZIF-8 serves as a carbon and nitrogen source dispersing Fe sites, and promotes the formation of microporous structures during pyrolysis together with NaCl. Cu species are introduced onto the surface of Fe-N@PCFs to interact with Fe-Nx sites and alleviate the Fenton-like effect, synergistically enhancing the bifunctional oxygen electrocatalytic performance toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The fibrous structure improves the peak power density of ZAB and FZAB. The Cu/Fe-N@PCFs exhibits an ORR half-wave potential (E1/2) of 0.865 V (vs. 0.838 V for Pt/C) and an OER overpotential of 370 mV (vs. 305 mV for RuO2) at 10 mA cm−2. The ZAB achieves a peak power density of 278.2 mW cm−2 (vs. 145.5 mW cm−2 for Pt/C + RuO2) and durability of 190 h. The self-supporting Cu/Fe-N@PCFs is assembled as FZAB, delivering a peak power density of 82.4 mW cm−2 (vs. 16.4 mW cm−2 for Pt/C + RuO2) and durability of 17 h. This study provides significant perspectives on constructing flexible catalysts, potentially advancing the development of ZABs and FZABs.

Polyurethanes (PUs) have emerged as promising candidates for next-generation solid polymer electrolytes (SPEs) due to their tunable structures and excellent mechanical properties. However, their application in solid-state lithium metal batteries (SSLMBs) is hindered by insufficient ion conduction and cycling stability. Herein, we introduce a functional zwitterionic extender between hard segments in the PU chain structure, which effectively immobilizes TFSI-anions while suppresses polymer crystallization, thereby notably promoting the Li+ transport. Diverse spectroscopic techniques combined with density functional theory (DFT) calculations confirm the crucial role of the zwitterionic group in achieving overall improvement of SPEs. The engineered zwitterionic PU SPE exhibits an ionic conductivity of 1.60 & times; 10-4 S cm-1 and a high Li+ transference number of 0.65 at 60 degrees C, alongside robust mechanical strength and thermal stability. The lithium metal symmetric cell demonstrates ultralong cycling stability for 4000 h, and the Li||LFP full cell achieves a high specific capacity of 166.5 mAh g-1 with 93.1% capacity retention after 250 cycles. This work highlights the potential of zwitterionic modification for developing advanced PU-based SPEs with improved conductivity, mechanical strength, and interfacial stability for high-energy-density SSLMBs.

The interface quality, one of critical factors, governs the properties of few-layer graphene, which exhibits exclusive electrical and mechanical properties owing to the strong interlayer coupling. However, the fabrication of interface-clean few-layer graphene still remains challenging. Conventional stacking techniques often introduce interfacial contamination, such as amorphous carbon and residual impurities, which critically deteriorate the interlayer coupling and compromise the uniformity and reliability of graphene-based devices. Here, we present an active oxygen treatment (AOT) strategy to effectively remove surface impurities and amorphous carbon on graphene before stacking, yielding wafer-scale few-layer graphene with clean interface and controlled layer numbers. As-fabricated few-layer graphene exhibits excellent structural integrity (u0026gt; 95%), flatness (Ra of ~ 2.3 nm), and uniformity. The suspended few-layer graphene shows superior mechanical stability due to the clean interface, which remains stable under repeated thermal shocks up to 1200 K, significantly outperforming counterparts assembled via conventional methods. Thermal light emitters based on the suspended few-layer graphene demonstrates strong visible-to-near-infrared emission, with lattice temperature reaches ~ 900 K and a working lifetime of ~ 70 min. This work highlights the potential of AOT in advancing the optoelectronic applications of graphene through precise interface engineering.

Carbon-based single-atom catalysts (SACs) often face a tradeoff between defect density and graphitization, leading to a compromise between activity and durability. In this study, carbon aerogel-based SACs are prepared via a two-step pyrolysis procedure with controllable mesoporous structures and graphitization by regulating the size of SiO2 nanoparticle templates and pyrolysis conditions. The second pyrolysis of the samples is found to help stabilize the carbon framework and create irregular mesopores, forming abundant edge sites that promote *OH desorption by lowering the d-band center of the Fe atomic sites and hence enhance the oxygen reduction reaction (ORR) kinetics. The optimal catalyst (PCA/Fe-2) displays a half-wave potential of +0.92 V towards ORR in alkaline media, with a minimal potential decay (11 mV) after 15,000 continuous cycles. With such a remarkable electrocatalytic performance, PCA/Fe-2 is used as the cathode catalyst to assemble a low-temperature zinc-air battery, which delivers a peak power density of 85.1 mW cm−2 and excellent durability after 2700 charging-discharging cycles at −30 °C, indicating promising low-temperature adaptability. These findings underscore the significance of substrate engineering in modulating the electrocatalytic performance of carbon-supported SACs for subambient electrochemical energy technologies.

Under the carbon peak and neutrality targets, green hydrogen is a cornerstone for zero-carbon energy systems. Constrained by freshwater scarcity, conventional water electrolysis faces bottlenecks, making direct seawater electrolysis (DSE) a promising route. However, complex seawater components induce chloride corrosion, metal precipitation, and membrane fouling, severely hindering practical applications. This review transcends the sole focus on electrocatalysts, emphasizing multi-level synergy across materials, interfaces, devices, and marine environments toward realistic ocean conditions. We systematically elucidate reaction competition, ion interactions, and interfacial microenvironment evolution, providing a cross-scale summary from catalysts to membranes and electrolyzers, with a four-dimensional evaluation framework. Recent kW-to-MW demonstrations validate technical feasibility. Future integration of DSE with offshore renewables and marine resource utilization will overcome bottlenecks and promote carbon neutrality.

Aqueous proton batteries (APBs) hold promise for high-rate energy storage, but their development is hindered by the instability of α-MoO3 electrodes, which suffer from dissolution and hydrogen evolution reactions. Herein, we report a bond-weakening engineering strategy via Si doping to boost proton transport in α-MoO3. The introduced Si(IV) forms Mo-O─Si linkages, reducing electron density around oxygen and weakening O─H bonds, thereby facilitating proton desorption and migration. The optimized Mo0.8Si0.2O3-x electrode achieves a high specific capacity of 223.03 mAh g-1 at 1 A g-1 and retains 63.57% capacity at 20 A g-1, vastly outperforming pristine α-MoO3. In a full cell with a vanadium hexacyanoferrate (VHCF) cathode, the Mo0.8Si0.2O3-x anode exhibits exceptional cycling durability (91.87% capacity retention after 4000 cycles at 8 A g-1). Density functional theory calculations confirm a reduced bandgap and lower proton diffusion barrier, underscoring the potential of non-metal doping for high-rate proton batteries.

Traditional technologies for SO2 pollution control in industrial flue gas face challenges of high energy consumption (Esp)and low-value-added products. This study presents a membrane-free Pt/Ti electrode-based electrocatalytic system, which achieves synergistic conversion of SO2 into H2SO4 and elemental sulfur (S0) by coupling anode SO2 oxidation reaction (SOR) with cathode SO2 reduction reaction (SRR). Electrochemical tests identify that maintaining a dynamic balance between the "ambient SO2 concentration" and the "anodic potential" is the key to optimizing reaction kinetics. In constant current mode, a 10-min SO2 pre-bubbling strategy reduces Esp of H2SO4 production from 1.27 to 0.58 kWh/kg, a 54.3% reduction from the non-pre-bubbling control, yielding an economic benefit coefficient (EBC) of 2.09. The constant total potential mode exhibits excellent dynamic self-regulation ability, enabling adaptation to SO2 concentration fluctuations through realtime adjustment of anode and cathode potentials to sustain reaction efficiency. This work provides fundamental insights into reaction mechanisms and practical guidelines for material design and operational optimization, paving the way for low Esp, high efficiency flue gas purification and valorization.

To facilitate the practical application of solid-state lithium metal batteries (SSLMBs), using composite solid electrolytes (CSEs) with both inorganic and polymer components that can overcome the disadvantages of any single component is an effective design method. However, the poor compatibility between inorganic and polymer phase often leads to discontinuous channels for ion transport and insufficient strength for suppressing lithium dendrites. Herein, a class of porous topological design strategy-established by self-assembly of wheel-like titanium-oxo clusters modified with polyethylene glycol (TOC@PEG) - that resolves the compatibility with the poly(ethylene oxide) (PEO) matrix is described. The self-assembled cluster topology enabled composite electrolyte (PEO/TOC@PEG) exhibits not only high Li-ion conductivity (2.32 x 10-3 S cm-1 at 60 degrees C), but also superb resistance to lithium dendrites. The Li|| PEO/TOC@PEG||Li battery can operate for 6000 h at 0.1 mA cm-2. The Li metal batteries demonstrate using LiFePO4 (LFP) cathodes exhibits excellent cycle stability under 0.5 C at 60 degrees C and 0.2 C at 35 degrees C, with a capacity retention of 85.5% after 800 cycles and 95.4% after 300 cycles, respectively, showing promising prospects for solid-state battery applications. This work provides a rational design strategy to address interfacial and ionic transport challenges in SSLMBs.

Central to the development of electrocatalysts that are cost-effective and highly functional are the synthesis of materials and the meticulous delineation of their morphology. This article introduces a solvent-thermal method for constructing ruthenium-based electrocatalysts (Ru/MIL-53@NF), distinguished by the in situ generation of ruthenium nanoparticles (NPs) on MIL-53 with notable dispersion. The procedure requires precise control over ruthenium integration and results in electrocatalysts with exceptional dispersion properties. Furthermore, the optimally engineered Ru/MIL-53@NF exhibited outstanding electrocatalytic hydrogen evolution performance, registering an overpotential of merely 17 mV at 10 mA cm-2 and a Tafel slope of 53.7 mV dec-1, thus outstripping the standard 20 wt% Pt/C benchmark. This research highlights the careful calibration of synthetic parameters to forge ruthenium-based electrocatalysts with both high efficacy and stability.

All-solid-state lithium metal batteries (ASSLMBs) have currently garnered significant academic and industrial interest, due to their great potential to overcome intrinsic shortages of poor energy density and unsatisfactory safety of liquid-state lithium-ion batteries. Recently, many efforts have been made to move the progress of solid electrolytes (SEs) forward for ASSLMBs, especially on the understanding and optimization of lithium-ion conduction in SEs. Herein, we summarize a review of recent design strategies for rational SEs that display enhanced lithium-ion conduction, as well as the discussion on design principles and working mechanisms for boosted performance and stability of ASSLMBs. Given the intimate relationship between the lithium-ion conduction mechanism and the composition of SEs, the reported SEs can generally be classified into single-phase SEs and composite SEs. In detail, single-phase SEs contain three typical categories, e.g., polymer-based, inorganic, and plastic crystal-based SEs. For composite SEs, there are also three main kinds, including polymer-inorganic, plastic crystal-polymer, and plastic crystal-polymer-inorganic ternary composite SEs. The state-of-the-art literature and representative materials have been carefully discussed and analyzed, with the corresponding factors of enhancing lithium-ion conduction highlighted. Finally, an outlook for future directions to design advanced SEs with efficient lithium-ion conduction is presented for the development of ASSLMBs.

Electrochemical water oxidation for H 2 O 2 synthesis is an environmentally friendly, sustainable production process that generates H 2 O 2 directly from water. This approach shows promise in overcoming the energy consumption and transportation limitations of traditional anthraquinone-based methods. However, the process is thermodynamically less favorable than the oxygen evolution reaction. Current research primarily focuses on developing highly active and selective anode catalysts through strategies such as doping, defect engineering, and interfacial modifications. Often overlooked in this study is the role of electrolytes. Recent studies indicate that carbonates in 2e − water oxidation reaction function not only as buffers or proton carriers, but also as key reaction participants that significantly influence H 2 O 2 production pathways and efficiency. Nevertheless, a comprehensive summary of their regulatory mechanisms is lacking. Against this backdrop, this paper provides a systematic review of the progress of research on 2e − WOR-mediated H 2 O 2 synthesis in carbonate media. The paper summarizes the performance of different electrode materials in this system and focuses on the detailed mechanisms of H 2 O 2 synthesis under various electrode materials, including metal oxide, carbon, and porphyrin electrodes. Several studies suggest that carbonates redirect the reaction pathway from 4e − oxygen evolution to 2e − H 2 O 2 production by forming CO 3 2− and percarbonate intermediates (C 2 O 6 2− and HCO 4 − ). This significantly enhances H 2 O 2 selectivity. The paper also summarizes the effects of CO 3 2− /HCO 3 − adsorption energies, cation effects, and flow reactor design on H 2 O 2 synthesis. Finally, the paper identifies key challenges and future opportunities in this field, emphasizing the need to combine in situ characterization and theoretical calculations to deeply reveal reaction mechanisms and identify key intermediates. This approach will provide the theoretical foundation for designing high-performance catalysts and reactors, ultimately advancing the industrial application of electrolytic H 2 O 2 synthesis technology.

The targeted introduction of heteroatomic metal aggregates has been proven to be a feasible and efficient strategy to improve the activity and stability of single-atom electrocatalysts for oxygen reduction reaction (ORR). However, the reported as-prepared electrocatalysts normally possess uniform inner structures, which cannot endow different nanoregions with specific functions. Herein, we propose a unique strategy to achieve heterogeneously functionalized electrocatalysts by precisely architecting sphere-like CuFe alloys as electron-rich containers, line-like carbon nanotubes (CNTs) as conductive bridges and cube-like FeN4 frameworks as main active centers. In this special sphere-line-cube (SLC) structural design, CuFe alloys nano-spheres supply adequate charge flow to active FeN4 nano-cubes with the help of CNTs nano-lines, thereby modulating the d-band electron density of Fe-N-C to match the absorption/desorption energy requirement of crucial intermediates. Therefore, ascribed to this rational design of nanoregion heterogeneous structure, the intrinsic activity of the optimized electrocatalyst has been highly enhanced. As a result, the CuFe-CNTs-FeN4 electrocatalyst exhibits remarkable ORR activity with a half-wave potential (E1/2) of 0.90V versus the reversible hydrogen electrode and only 9mV decline of E1/2 after 10,000 potential cycles in alkaline electrolyte. Moreover, the zinc-air battery employing CuFe-CNTs-FeN4 as the cathode electrocatalyst displays an outstanding long-term cycle stability of over 1600 cycles and a high round-trip efficiency above 60%, as well as its excellent feasibility in flexible solid-state zinc-air batteries (ZABs). This work provides a novel and valuable strategy to realize d-band modulation by introducing a nanoregion heterogeneous structure, aiming at boosting ORR performance for practical ZABs.

Molten salt mixtures of LiF, NaF, and BeF2 are widely recognized as potential solvents and coolants in molten salt reactor applications. The structural effects of LiF addition to the ternary salt were investigated using HT-NMR and solid-state NMR techniques. A distinct phase transition was identified using HT-NMR during the melting process of LiF-NaF-BeF2 ternary salts. The results indicated that the addition of LiF facilitates the transition from a crystalline to an amorphous structure. The influence of Li+ and Na+ on the amorphous structure was analyzed, revealing that Li+ ions exhibit relatively strong interactions with Be-F oligomers. Furthermore, as the temperature increases, the rapid dynamics weaken the interactions between Li+ ions and Be-F oligomers. This weakening of interactions results in the remarkable phase transformation of Be-F oligomers into polymeric chains and networks.