Tailoring Interfacial Charge Transfer of Epitaxially Grown Ir Clusters for Boosting Hydrogen Oxidation Reaction

The sluggish kinetics of hydrogen oxidation reaction (HOR) is one of the critical challenges for anion exchange membrane fuel cells. Here, we report epitaxial growth of Ir nanoclusters (<2 nm) on a MoS₂ surface (Ir/MoS₂) and optimize the alkaline HOR activity via tailoring interfacial charge transfer between Ir clusters and MoS₂. The electron transfer from MoS₂ to Ir clusters can effectively prevent the oxidation of Ir clusters, which is not the case for carbon-supported Ir nanoclusters (Ir/C) synthesized using the same method. Moreover, the HOR performance of the Ir/MoS₂ can be further optimized by tuning the hydrogen binding energy (HBE) via a precise annealing treatment. A substantial exchange current density of 1.28 mA cm_ECSA⁻² is achieved in the alkaline medium, which is ∼10 times over that of Ir/C. The HOR mass-specific activity of Ir/MoS₂ heterostructure is as high as 182 mA mg_Ir⁻¹. The experimental results and density functional theory calculations reveal that the significant improved HOR activity is attributed to the decreased HBE, which highlights epitaxial growth is an effective way for boosting catalytic activity of heterostructured catalysts.     

Multi-Interface Engineering of Self-Supported Nickel/Yttrium Oxide Electrode Enables Kinetically Accelerated and Ultra-Stable Alkaline Hydrogen Evolution at Industrial-Level Current Density

The development of highly active and robust non-noble-metal electrocatalysts for alkaline hydrogen evolution reaction (HER) at industrial-level current density is the key for industrialization of alkaline water electrolysis. Herein, a superhydrophilic self-supported Ni/Y₂O₃ heterostructural electrocatalyst is constructed by a high-temperature selective reduction method, which demonstrates excellent catalytic performance for alkaline HER at high current density. Concretely, this catalyst can drive 10 mA cm⁻² at a low overpotential of 61.1 ± 3.7 mV, with a low Tafel slope of 52.8 mV dec⁻¹. Moreover, it also shows outstanding long-term durability at high current density of 1000 mA cm⁻² for 500 h in 1 m  KOH, evidently exceeding the metallic Ni and Pt/C(20%) catalysts. The superior HER activity can be attributed to the multi-interface engineering of the Ni/Y₂O₃ electrode. Construction of Ni/Y₂O₃ heterogeneous interface with dual active sites lowers the energy barrier of water dissociation and optimizes the hydrogen adsorption energy, thus synergistically accelerating the overall HER kinetics. Also, its superhydrophilic self-supported electrode structure with the firm electrocatalyst-substrate interface and weakened electrocatalyst-bubble interfacial force ensures rapid charge transfer, prevents catalyst shedding, and expedites the H₂ gas bubble release timely, further enhancing the catalytic activity and stability at high current density.     

Defect Engineering Promoted Ultrafine Ir Nanoparticle Growth and Sr Single-Atom Adsorption on TiO2 Nanowires to Achieve High-Performance Overall Water Splitting in Acidic Media

This work reports the use of the metal-support interaction strengthening through defect engineering and single atom adsorption to the supports to increase the catalytic activities of metals. Specifically, the plasma treated TiO₂ nanowires with the Ir nanoparticle growth and the Sr single atom adsorption (the Ir@Sr-p-TiO₂ NWs) are synthesized and demonstrated to be efficient catalysts for OER and HER. They only need overpotentials of 250 and 32 mV to drive 10 mA cm⁻² for OER and HER, respectively. Their OER and HER activities are much higher than the commercial IrO₂ and Pt/C. The high activities of the Ir@Sr-p-TiO₂ NWs mainly arise from the strengthened metal-support interactions between the Ir nanoparticles and the p-TiO₂ NWs, achieved by the plasma generated oxygen defects (Vo·) and the Sr adsorption on the p-TiO₂ NWs. Analysis and DFT calculations indicate that the Vo· and Sr adsorption can promote the charge transfer from the p-TiO₂ NWs to the Ir nanoparticles, optimizing the adsorptions of the OER and HER intermediates on the O- and H-covered Ir nanoparticles. Additionally, the strong metal-support interactions can increase the stabilities of the Ir NPs against the chemical corrosions, increasing the OER and HER durabilities of the Ir@Sr-p-TiO₂ NWs.     

High-Areal-Capacity and Long-Cycle-Life All-Solid-State Lithium-Metal Battery by Mixed-Conduction Interface Layer

The rapid growth of lithium dendrites has seriously hindered the development and practical application of high-energy-density all-solid-state lithium metal batteries (ASSLMBs). Herein, a soft carbon (SC)-nano Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) (with high ionic conductivity and diffusion coefficient) mixed ionic and electronic conducting interface layer is designed to promote the rapid migration of Li⁺ at the interfacial layer, induce the uniform deposition of lithium metal on nanoscale (nano) LLZTO ion-conducting network inside the interface layer, effectively suppress the growth of lithium dendrites, and significantly improve the electrochemical performance of ASSLMBs. LiZrO₂@LiCoO₂(LZO@LCO)/Li₆PS₅Cl(LPSCl)-nano LLZTO/Li ASSLMB achieves high current density (12.5 mA cm⁻²), ultra-high areal capacity (15 mAh cm⁻², corresponding to LZO@LCO mass loadings of 111.11 mg cm⁻²), and ultra-long cycle life (20 000 cycles). Therefore, the introduction of SC-nano LLZTO mixed conducting interface layer can greatly improve the interfacial stability between solid-state electrolyte (SSE) and lithium metal anode to enable dendrite-free ASSLMBs.     

Ruthenium Triazine Composite: A Good Match for Increasing Hydrogen Evolution Activity through Contact Electrification

The development of Pt‐free catalysts for the alkaline hydrogen evolution reaction (HER), which is widely used in industrial scale water‐alkali electrolyzers, remains a contemporary and pressing challenge. Ruthenium (Ru) has excellent water‐dissociation abilities and could be an alternative water splitting catalyst. However, its large hydrogen binding energy limits HER activity. Here, a new approach is proposed to boost the HER activity of Ru through uniform loading of Ru nanoparticles on triazine‐ring (C₃N₃)‐doped carbon (triNC). The composite (Ru/triNC) exhibits outstanding HER activity with an ultralow overpotential of ≈2 mV at 10 mA cm^?2; thereby making it the best performing electrocatalyst hitherto reported for alkaline HER. The calculated metal mass activity of Ru/triNC is >10 and 15 times higher than that of Pt/C and Pt/triNC. Both theoretical and experimental studies reveal that the triazine‐ring is a good match for Ru to weaken the hydrogen binding on Ru through interfacial charge transfer via increased contact electrification. Therefore, Ru/triNC can provide the optimal hydrogen adsorption free energy (approaching zero), while maintaining the strong water‐dissociation activity. This study provides a new avenue for designing highly efficient and stable electrocatalysts for water splitting.     

Single Ru Atoms Stabilized by Hybrid Amorphous/Crystalline FeCoNi Layered Double Hydroxide for Ultraefficient Oxygen Evolution

In view of the sluggish kinetics suppressing the oxygen evolution reaction (OER), developing efficient and robust OER catalysts is urgent and essential for developing efficient energy conversion technologies. Herein, hybrid amorphous/crystalline FeCoNi layered double hydroxide (LDH)-supported single Ru atoms (Ru SAs/AC-FeCoNi) are developed for enabling a highly efficient electrocatalytic OER. The amorphous outer layer in Ru SAs/AC-FeCoNi is composed of abundant defect sites and unsaturated coordination sites, which can serve as anchoring sites to stabilize single Ru atoms. The crystalline inner has a highly symmetric rigid structure, thereby strengthening the stability of support for a long-lasting OER. The synergistic effects endow this hybrid catalyst with extremely low overpotential (205 mV at 10 mA cm⁻²). Density functional theory calculation indicates that single Ru atoms stabilized by hybrid amorphous/crystalline FeCoNi LDH facilitate the formation of Ru–O* (rate-determining step), thus accelerating the OER process.     

Coordination Engineering of N,O Co-Doped Cu Single Atom on Porous Carbon for High Performance Zinc Metal Anodes

Traditional challenges of poor cycling stability and low Coulombic efficiency in Zinc (Zn) metal anodes have limited their practical application. To overcome these issues, this work introduces a single metal-atom design featuring atomically dispersed single copper (Cu) atoms on 3D nitrogen (N) and oxygen (O) co-doped porous carbon (CuNOC) as a highly reversible Zn host. The CuNOC structure provides highly active sites for initial Zn nucleation and further promotes uniform Zn deposition. The 3D porous architecture further mitigates the volume changes during the cycle with homogeneous Zn²⁺ flux. Consequently, CuNOC demonstrates exceptional reversibility in Zn plating/stripping processes over 1000 cycles at 2 and 5 mA cm⁻² with a fixed capacity of 1 mAh cm⁻², while achieving stable operation and low voltage hysteresis over 700 h at 5 mA cm⁻² and 5 mAh cm⁻². Furthermore, density functional theory calculations show that co-doping N and O on porous carbon with atomically dispersed single Cu atoms creates an efficient zincophilic site for stable Zn nucleation. A full cell with the CuNOC host anode and high loading V₂O₅ cathode exhibits outstanding rate-capability up to 5 A g⁻¹ and a stable cycle life over 400 cycles at 0.5 A g⁻¹.     

Bulk-Heterojunction Electrocatalysts in Confined Geometry Boosting Stable,Acid/Alkaline-Universal Water Electrolysis

Alkaline water splitting electrocatalysts have been studied for decades; however, many difficulties remain for commercialization, such as sluggish hydrogen evolution reaction (HER) kinetics and poor catalytic stability. Herein, by mimicking the bulk-heterojunction morphology of conventional organic solar cells, a uniform 10 nm scale nanocube is reported that consists of subnanometer-scale heterointerfaces between transition metal phosphides and oxides, which serves as an alkaline water splitting electrocatalyst; showing great performance and stability toward HER and oxygen evolution reaction (OER). Interestingly, the nanocube electrocatalyst reveals acid/alkaline independency from the synergistic effect of electrochemical HER (cobalt phosphide) and thermochemical water dissociation (cobalt oxide). From the spray coating process, nanocube electrocatalyst spreads uniformly on large scale (≈6.6 × 5.6 cm²) and is applied to alkaline water electrolyzers, stably delivering 600 mA cm⁻² current for >100 h. The photovoltaic-electrochemical (PV-EC) system, including silicon PV cells, achieves 11.5% solar-to-hydrogen (STH) efficiency stably for >100 h.     

Robust Hybrid Solid Electrolyte Interface Induced by Zn-Poor Electric Double Layer for A Highly Reversible Zinc Anode

Aqueous Zn-ion batteries (AZIBs) show great potential in new energy storage devices due to low cost, inherent safety, and environmental friendliness. However, the severe dendrites and side reactions on the anode greatly constrain their practical application. Herein, a novel colloidal electrolyte composed of ZnSO₄ and sodium carboxymethyl cellulose (CMC-Na) has been developed for inhibiting dendrite growth on Zn anode. Molecular dynamics (MD) simulation confirms that CMC-Na alters the electric double layer (EDL) structure of Zn anode surface to reduce the content of water and SO₄²⁻ and inhibit side reactions. More importantly, an organic/inorganic hybrid solid electrolyte interface (SEI) layer is in situ constructed during the cycling, which enables ultrastable Zn plating/stripping (> 2000 h) under high current density (5 mA cm⁻², 5 mAh cm⁻²) and high coulombic efficiency (99.8%) for more than 1000 cycles. Meanwhile, zinc-ion hybrid capacitors (ZIHCs) with the colloidal electrolyte exhibit a favorable capacitance retention of 97% after 15000 cycles at the current density of 2 A g⁻¹. Even at a high current density of 5 A g⁻¹, it still has a capacitance retention of 96% after 30000 cycles. This study presents a novel electrolyte strategy for the formation of ultrastable electrode-electrolyte interfaces in AZIBs.     

Highly Stable Vertically Oriented 2H-NbS2 Nanosheets on Carbon Nanotube Films toward Superior Electrocatalytic Activity

2D metallic transition-metal dichalcogenides (MTMDCs) have attracted widespread research interest in the exploration of fundamental physical issues and energy-related fields. Although relatively high catalytic activity has been predicted theoretically in the new type MTMDCs-based electrocatalysts, their hydrogen evolution reaction (HER) performance is severely hampered by the insufficient catalytic stability due to structural degradation during long-time use and limited active sites in planar electrode structures. Herein, the scalable synthesis of vertically-oriented 2H-NbS₂ nanosheets is reported on low-cost carbon nanotube (CNT) film substrates by a facile chemical vapor deposition route. The 3D vertically-oriented 2H-NbS₂ nanosheets present abundant edge active sites and strong interface coupling with CNT thus possessing exceptional mechanical stability. These features impart the 3D nanosheets catalysts with remarkably low overpotentials of ≈55 mV at 10 mA cm⁻² and ultra-high exchange current density of ≈1445 µA cm⁻², and negligible performance degradation after 200 h operation at the large current density, which are superior to those of other TMDCs-based catalysts. This work hereby provides novel perspectives for the batch synthesis and application of 3D MTMDCs-based electrocatalysts with greatly improved electrocatalytic performance and stability that are needed for practical applications.     

Hierarchically Porous,Ultrathick, “Breathable” Wood‐Derived Cathode for Lithium‐Oxygen Batteries

In this work, a hierarchically porous and ultrathick “breathable” wood‐based cathode for high‐performance Li‐O₂ batteries is developed. The 3D carbon matrix obtained from the carbonized and activated wood (denoted as CA‐wood) serves as a superconductive current collector and an ideal porous host for accommodating catalysts. The ruthenium (Ru) nanoparticles are uniformly anchored on the porous wall of the aligned microchannels (denoted as CA‐wood/Ru). The aligned open microchannels inside the carbon matrix contribute to unimpeded oxygen gas diffusion. Moreover, the hierarchical pores on the microchannel walls can be facilely impregnated by electrolyte, forming a continuous supply of electrolyte. As a result, numerous ideal triphase active sites are formed where electrolyte, oxygen, and catalyst accumulate on the porous walls of microchannels. Benefiting from the numerous well‐balanced triple‐phase active sites, the assembled Li‐O₂ battery with the CA‐wood/Ru cathode (thickness: ≈700 µm) shows a high specific area capacity of 8.58 mA h cm^?2 at 0.1 mA cm^?2. Moreover, the areal capacity can be further increased to 56.0 mA h cm^?2 by using an ultrathick CA‐wood/Ru cathode with a thickness of ≈3.4 mm. The facile ultrathick wood‐based cathodes can be applied to other cathodes to achieve a super high areal capacity without sacrificing the electrochemical performance.     

Dislocation Network-Boosted PtNi Nanocatalysts Welded on Nickel Foam for Efficient and Durable Hydrogen Evolution at Ultrahigh Current Densities

Large-scale application of alkaline water electrolysis for high-rate hydrogen production is severely hindered by high electricity cost, mainly due to difficulties to acquire cost-effective catalytic electrodes with both extremely low overpotential and long-term durability at ultrahigh current densities (≥1 A cm⁻²). Here it is demonstrated that by adopting a synthetic method of laser direct writing in liquid nitrogen via a commercial laser welding machine, a remarkably efficient and durable electrode with large area and low platinum content is obtained, where PtNi nanocatalysts with dislocation network are firmly welded on a nickel foam (NF). The dense dislocation network not only improves intrinsic activity of a majority of surface-active sites induced by coupled compressive-tensile strains synergistically promoting both Volmer and Tafel steps of alkaline hydrogen evolution reaction (HER), but also well stabilizes surface dislocations for HER at ultrahigh current densities. Such a robust electrode achieves record-low overpotentials of 5 and 63 mV at 10 and 1000 mA cm⁻² in alkaline medium, respectively, exhibiting negligible activity decay after 300 h chronoamperometric test at 1 A cm⁻². It displays a high Pt mass activity 16 times higher than 20 wt% Pt/C loaded on NF, surpassing most of the recently reported efficient Pt-based catalysts.     

Cathodic reduction of hexavalent chromium [Cr(VI)] coupled with electricity generation in microbial fuel cells

A novel approach to Cr(VI)-contaminated wastewater treatment was investigated using microbial fuel cell technologies in fed-batch mode. By using synthetic Cr(VI)-containing wastewater as catholyte and anaerobic microorganisms as anodic biocatalyst, Cr(VI) at 100 mg/l was completely removed during 150 h (initial pH 2). The maximum power density of 150 mW/m² (0.04 mA/cm²) and the maximum open circuit voltage of 0.91 V were generated with Cr(VI) at 200 mg/l as electron acceptor. This work verifies the possibility of simultaneous electricity production and cathodic Cr(VI) reduction.     

Construction of Ordered Atomic Donor–Acceptor Architectures in bcc IrGa Intermetallic Compounds toward Highly Electroactive and Stable Overall Water Splitting

Benefiting from ordered atomic structures and strong d-orbital interactions, intermetallic compounds (IMCs) are promising electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, the body-centered cubic IrGa IMCs with atomic donor–acceptor architectures are synthesized and anchored on the nitrogen-doped reduced graphene oxide (i.e., IrGa/N-rGO). Structural characterizations and theoretical calculations reveal that the electron-rich Ir sites are atomically dispersed in IrGa/N-rGO, facilitating the electron transfer between Ir atoms and adsorbed species, which can efficiently decrease the energy barriers of the potential determining step for both HER and OER. Impressively, the IrGa/N-rGO||IrGa/N-rGO exhibits excellent performance for overall water splitting in alkaline medium, requiring a low cell voltage of 1.51 V to achieve 10 mA cm⁻², meanwhile, exhibiting no significant degradation for 100 h. This work demonstrates that the rational design of noble metal electrocatalysts with donor–acceptor architectures is beneficial for catalytic reactions in energy conversion applications.     

In-Situ Constructuring of Copper-Doped Bismuth Catalyst for Highly Efficient CO2 Electrolysis to Formate in Ampere-Level

CO₂ electrochemical reduction (CO₂RR) can mitigate environmental issues while providing valuable products, yet challenging in activity, selectivity, and stability. Here, a CuS-Bi₂S₃ heterojunction precursor is reported that can in situ reconstruct to Cu-doped Bismuth (CDB) electrocatalyst during CO₂RR. The CDB exhibits an industrial-compatible current density of −1.1 A cm⁻² and a record-high formate formation rate of 21.0 mmol h⁻¹ cm⁻² at −0.86 V versus the reversible hydrogen electrode toward CO₂RR to formate, dramatically outperforming currently reported catalysts. Importantly, the ultrawide potential region of 1050 mV with high formate Faradaic efficiency of over 90% and superior long-term stability for more than 100 h at −400 mA cm⁻² can also be realized. Experimental and theoretical studies reveal that the remarkable CO₂RR performance of CDB results from the doping effect of Cu which optimizes adsorption of the *OCHO and boosts the structural stability of metallic bismuth catalyst. This study provides valuable inspiration for the design of element-doping electrocatalysts to enhance catalytic activity and durability.     

Hybrid 3D-Ordered Membrane Electrode Assembly (MEA) with Highly Stable Structure,Enlarged Interface,and Ultralow Ir Loading by Doping Nano TiO2 Nanoparticles for Water Electrolyzer

Proton exchange membrane water electrolysis (PEMWE) is a very promising and sustainable hydrogen production technology. Currently, there is a growing interest in achieving ordered structures within membrane electrode assembly (MEA) for PEMWE. However, both ordered electron conductor and ordered proton conductor structures are single component structure, which still have many shortcomings. In this work, a hybrid ordered membrane electrodes assembly based on cone-shaped is constructed Nafion array with rough surface by introducing TiO₂ nanoparticles to Nafion emulsion. As a result, this hybrid ordered MEA achieves a high surface roughness of 3.39 nm that is 2.64 times higher than that of ordered MEA without TiO₂ nanoparticles doped and current density up to 2.48 A cm⁻² at 2 V with 14.4 µg cm⁻² (Ir) catalyst loading. This work provides a new hybrid ordered structure for MEA and exhibits the great potential of enhancing the interfacial contact between the catalyst layer and Nafion membrane to improve PEMWE performance.     

Interrelation Between External Pressure,SEI Structure,and Electrodeposit Morphology in an Anode-Free Lithium Metal Battery

The interrelation is explored between external pressure (0.1, 1, and 10 MPa), solid electrolyte interphase (SEI) structure/morphology, and lithium metal plating/stripping behavior. To simulate anode-free lithium metal batteries (AF-LMBs) analysis is performed on “empty” Cu current collectors in standard carbonate electrolyte. Lower pressure promotes organic-rich SEI and macroscopically heterogeneous, filament-like Li electrodeposits interspersed with pores. Higher pressure promotes inorganic F-rich SEI with more uniform and denser Li film. A “seeding layer” of lithiated pristine graphene (pG@Cu) favors an anion-derived F-rich SEI and promotes uniform metal electrodeposition, enabling extended electrochemical stability at a lower pressure. State-of-the-art electrochemical performance is achieved at 1MPa: pG-enabled half-cell is stable after 300 h (50 cycles) at 1 mA cm⁻² rate −3 mAh cm⁻² capacity (17.5 µm plated/stripped), with cycling Coulombic efficiency (CE) of 99.8%. AF-LMB cells with high mass loading NMC622 cathode (21 mg cm⁻²) undergo 200 cycles with a CE of 99.4% at C/5-charge and C/2-discharge (1C = 178 mAh g⁻¹). Density functional theory (DFT) highlights the differences in the adsorption energy of solvated-Li⁺ onto various crystal planes of Cu (100), (110), and (111), versus lithiated/delithiated (0001) graphene, giving insight regarding the role of support surface energetics in promoting SEI heterogeneity.     

Ultrathin Reed Membranes: Nature's Intimate Ion-Regulation Skins Safeguarding Zinc Metal Anodes in Aqueous Batteries

The practical realization of aqueous zinc-ion batteries relies crucially on effective interphases governing Zn electrodeposition chemistry. In this study, an innovative solution by introducing an ultrathin (≈2 µm) biomass membrane as an intimate artificial interface, functioning as nature's ion-regulation skin to protect zinc metal anodes is proposed. Capitalizing on the inherent properties of natural reed membrane, including multiscale ion transport tunnels, abundant ─OH groups, and remarkable mechanical integrity, the reed membrane demonstrates efficacy in regulating uniform and rapid Zn²⁺ transport, promoting desolvation, and governing Zn (002) plane electrodeposition. Importantly, a unique in situ electrochemical Zn─O bond formation mechanism between the reed membrane and Zn electrode upon cycling is elucidated, resulting in a robustly adhered interface covering on the zinc anode surface, ultimately ensuring remarkable dendrite-free and highly reversible Zn anodes. Consequently, the approach achieves a prolonged cycle life for over 1450 h at 3 mA cm⁻²/1.5 mAh cm⁻² in symmetric Zn//Zn cells. Moreover, exceptional cyclic performance (88.95%, 4000 cycles) is obtained in active carbon-based cells with an active mass loading of 5.8 mg cm⁻². The approach offers a cost-effective and environmentally friendly strategy for achieving stable and reversible zinc anodes for aqueous batteries.     

A Comparative Study of a Novel Anti-reflective Layer to Improve the Performance of a Thin-Film GaAs Solar Cell by Embedding Plasmonic Nanoparticles

In this research work, a systematic design of a novel anti-reflective layer using embedded plasmonic nanoparticles is investigated for a thin-film GaAs solar cell. First, an anti-reflective layer that is made from ITO or SiO₂ is assumed in which Al nanoparticles are embedded inside them to manipulate the absorption and hence the photocurrent of a 500-nm GaAs solar cell. It is investigated that the Al nanoparticles embedded inside the anti-reflective coating improve the photocurrent of a GaAs solar cell. For instance, the 15.37 mA photocurrent is obtained for 500-nm bare GaAs cell, and it reached to 17.25 mA/cm² and 20.18 mA/cm² when an ITO anti-reflection is used with Al nanoparticles on top and inside that, respectively. It increases to 21.94 mA/cm² and 24.98 mA/cm² in the case of the anti-reflective layer made from SiO₂ and Al nanoparticles at the top side or inside that, respectively. Finally, using a double anti-reflective layer that is made from SiO₂-TiO₂, the maximum photocurrents of 23.79 mA/cm² and 24.68 mA /cm² are obtained when Al nanoparticles are at the top side or inside that, respectively. The simulation results show that the embedding Al nanoparticles in the anti-reflective layer can improve the photocurrent of a thin-film GaAs solar cell.

     

In Situ Vertically Aligned MoS2 Arrays Electrodes for Complexing Agent-Free Bromine-Based Flow Batteries with High Power Density and Long Lifespan

Bromine-based flow batteries (Br-FBs) are highly competitive for stationary energy storage due to their high energy density and cost-effectiveness. However, adding bromine complexing agents (BCAs) to electrolytes slows down Br₂/Br⁻ reaction kinetics, causing higher polarization and lower power density of Br-FBs. Herein, in situ vertically aligned MoS₂ nanosheet arrays on traditional carbon felt substrates as electrodes to construct high power–density BCA-free Br-FBs are proposed. MoS₂ arrays exhibit strong adsorption capacity to bromine, which helps the electrodes capture and retain bromine species. Even without BCAs, the battery self-discharge caused by bromine diffusion is also inhibited. Moreover, the rate-determining step of Br₂/Br⁻ reactions is boosted and the vertically aligned array structure provides sufficient sites, motivating Br₂/Br⁻ reaction kinetics and decreasing the battery polarization. The capacity retention rate of the BCA-free Br-FB based on MoS₂ arrays-based electrodes reaches 46.34% after the 24-h standing test at 80 mA cm⁻², meeting the requirements of practical applications. Most importantly, this BCA-free Br-FB exhibits a high Coulombic efficiency of 97.00% and an ultralong cycle life of 1000 cycles at a high current density of 200 mA cm⁻². This work provides an available approach to developing advanced electrode materials for high power–density and long-lifespan Br-FBs.