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Arsenic is the only beneficial impurity for copper electrorefining through inhibiting anode passivation and the formation of floating slimes. The behaviour of copper anodes with different content of arsenic were studied at high current density (>280 A/m 2). It showed that low arsenic anodes (As < 300 ppm) easily generated anode passivation, floating slimes and cathode nodules during the electrorefining proccess. The floating slimes, electrolyte, cathode and anode were observed and analyzed. As result, low arsenic anodes were more likely to be passivated due to their microstructure defects and irregular microstructure. Increasing electrolyte temperature and addition of glycerol were propitious to reduce low arsenic anodes’ passivation. The floating slimes occured when the concentration of As(III) in electrolyte decreased to 1 g/L, and they would be precipitated by polyacrylamide. All measures greatly improved the cathode quality at current density of 300 A/m 2.

Highlights The robust organic/inorganic hybrid interlayer derived from in situ formed tribofilms were fabricated by using a scalable rolling method. The interlayer facilitates dendrite-free lithium metal anodes by building local de-solvation environments near the interface and inhibiting both dendrite growth and electrolytes corrosion. The symmetrical cell exhibits a remarkable lifespan of 5,600 h (1.0 mA cm-2 and 1.0 mAh cm-2) and 1,350 cycles even at a harsh condition (18.0 mA cm-2 and 3.0 mAh cm-2).

This paper focuses on proton exchange membrane fuel cell (PEMFC) operation at current densities in the order of 6 A/cm2. Such high current densities are conceivable when the traditional carbon fiber papers are replaced with perforated metal plates as the gas diffusion layer to enhance waste heat removal, and at the same time the relative humidity inside the fuel cell is kept below 100% by applying appropriate operating conditions as was found in previous one-dimensional modeling work. In the current paper, we applied a three-dimensional, multi-phase computational fluid dynamics model based on Ansys-CFX to obtain additional insight into the underlying physics. The calculated pressure drops are in very good agreement with previous one-dimensional modeling work, and the current densities in all case studies are in the order of 5–6 A/cm2, but different from the previous one-dimensional study, the results suggest that the relative humidity is very close to 100% throughout the entire channel length when the inlet relative humidity is 100%, ensuring best hydration cell conditions and hence best performance. Importantly, the model results suggest that fuel cell performance at a high current density in conjunction with relatively low stoichiometric flow ratios around 1.5–2 is possible.

Hydrogen is now recognized as the primary alternative to fossil fuels due to its renewable, safe, high-energy density and environmentally friendly properties. Efficient hydrogen production through water splitting has laid the foundation for sustainable energy technologies. However, when hydrogen production is scaled up to industrial levels, operating at high current densities introduces unique challenges. It is necessary to design advanced electrocatalysts for hydrogen evolution reactions (HERs) under high current densities. This review will briefly introduce the challenges posed by high current densities on electrocatalysts, including catalytic activity, mass diffusion, and catalyst stability. In an attempt to address these issues, various electrocatalyst design strategies are summarized in detail. In the end, our insights into future challenges for efficient large-scale industrial hydrogen production from water splitting are presented. This review is expected to guide the rational design of efficient high-current density water electrolysis electrocatalysts and promote the research progress of sustainable energy.

Abstract Hot electron transistors (HETs) represent an exciting new device for integration into semiconductor technology, holding the promise of high‐frequency electronics beyond the limits of SiGe bipolar hetero transistors. With the exploration of 2D materials such as graphene and new device architectures, hot electron transistors have the potential to revolutionize the landscape of modern electronics. This study highlights a novel hot electron transistor structure with a record output current density of 800 A cm−2 and a high current gain α, fabricated using a scalable fabrication approach. The hot electron transistor structure comprises 2D hexagonal boron nitride and graphene layers wet transferred to a germanium substrate. The combination of these materials results in exceptional performance, particularly in terms of the highly saturated output current density. The scalable fabrication scheme used to produce the hot electron transistor opens up opportunities for large‐scale manufacturing. This breakthrough in hot electron transistor technology holds promise for advanced electronic applications, offering high current capabilities in a practical and manufacturable device.

Exploring highly efficient oxygen evolution reaction (OER) electrocatalysts is important for industrial water electrolysis, especially under high current densities (>1 A cm−2). High‐entropy alloy (HEA) with high surface OER activity and excellent electrical conductivity of the core is an ideal route to improve the catalytic activity. Herein, a combined theoretical and experimental approach to establish core–shell FeCoNiMoAl‐based HEA as a promising OER electrocatalyst is presented. Theoretical calculations combined with structure analyses indicate crystalline–amorphous (c–a) heterostructure of shell reduces the electron transfer resistance and generates more active sites, furthermore the crystalline core improves the conductivity and self‐supporting ability. HEA electrodes demonstrate superior OER performance with an overpotential (η) of 470 mV at 2 A cm−2 and no apparent degradation even after 330 h of continuous testing, notably, for overall water splitting the stability is more than 120 h at 2.06 V. The special core–shell structure achieves a win–win strategy for high OER activity and stability. These findings shed light on the structural design of HEA electrocatalysts and present a promising route to achieve highly efficient electrocatalysts for industrial water electrolysis and relevant energy conversion processes. [ABSTRACT FROM AUTHOR]

Exploring highly efficient oxygen evolution reaction (OER) electrocatalysts is important for industrial water electrolysis, especially under high current densities (>1 A cm−2). High‐entropy alloy (HEA) with high surface OER activity and excellent electrical conductivity of the core is an ideal route to improve the catalytic activity. Herein, a combined theoretical and experimental approach to establish core–shell FeCoNiMoAl‐based HEA as a promising OER electrocatalyst is presented. Theoretical calculations combined with structure analyses indicate crystalline–amorphous (c–a) heterostructure of shell reduces the electron transfer resistance and generates more active sites, furthermore the crystalline core improves the conductivity and self‐supporting ability. HEA electrodes demonstrate superior OER performance with an overpotential (η) of 470 mV at 2 A cm−2 and no apparent degradation even after 330 h of continuous testing, notably, for overall water splitting the stability is more than 120 h at 2.06 V. The special core–shell structure achieves a win–win strategy for high OER activity and stability. These findings shed light on the structural design of HEA electrocatalysts and present a promising route to achieve highly efficient electrocatalysts for industrial water electrolysis and relevant energy conversion processes. [ABSTRACT FROM AUTHOR]

As an important part of water splitting, the oxygen evolution reaction (OER) requires efficient, low-cost, and stable catalysts to overcome its sluggish kinetic barrier. In this study, based on previously reported OER catalyst materials of boron monosulfide mixed with graphene (r-BS+G), nickel foam (NF) is introduced as a supporting material for an r-BS+G electrocatalyst. The resulting r-BS+G-NF exhibits a very low overpotential at 10 (245 mV), 100 (308 mV), and 500 (405 mV) mA cm−2, with a low Tafel slope (56 mV dec−1). In addition, r-BS+G-NF exhibits high durability and can maintain high activity for more than 100 h at 100 mA cm−2. This is in sharp contrast to the catalyst without graphene (r-BS+NF), which shows lower durability. The results suggest that the unique morphology of the NF provides a large electrochemically active area and exposes more active sites on the surface of the prepared electrocatalyst, while the flexible graphene sheets play an important role as a support for effectively combining r-BS and NF. Consequently, the self-supporting structure can improve the OER performance as well as stability. Therefore, this study provides a promising strategy for use as an efficient and stable OER catalyst at high current densities. In the realm of electrocatalysis and the quest for sustainable energy conversion and storage technologies, our research introduces a distinctive contribution in the form of a nickel-foam-based boron monosulfide – graphene electrocatalyst (r-BS+G-NF) for the Oxygen Evolution Reaction (OER). Thanks to the porous structure of nickel foam and the important role of graphene in combining r-BS and nickel foam, r-BS+G-NF exhibits high catalytic activity and long durability for up to 100 hours. The findings presented in this paper represent a significant advancement in the field of electrocatalysis, with the potential to impact the development of cleaner and more efficient energy conversion and storage technologies. [ABSTRACT FROM AUTHOR]

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Rechargeable calcium batteries (RCB) are prospective candidates for sustainable energy storage, as they hold the promise of the high energy density of lithium‐ion batteries (LIBs) while simultaneously combining it with highly abundant raw materials. However, for long time, calcium batteries have faced severe issues with regard to cycling stability, until recently developments demonstrated improved battery cycle life when employing CaSn alloy anodes with fluorinated alkoxyborate electrolytes. These findings opened up the possibility to study cathode materials for RCBs not only in a more comparable manner, but also in a practical full cell design. As representative of emerging organic electrode materials (OEMs), we investigated tetrakis(4‐pyridyl) porphyrin as both free ligand (H2TPyP) and in the form of its copper MOF complex (CuTPyP−MOF) as active cathode species in RCBs. The cells demonstrated high capacities and excellent cycling stability at the same time. Even at elevated current densities of e. g. 2000 mA/g the full cells delivered stable capacities of ~90 mAh/g proving its excellent rate capability. This study explores the electrochemical performance of porphyrin active materials in calcium batteries and represents a significant step forward in the progress toward organic electrodes for multivalent energy storage systems. [ABSTRACT FROM AUTHOR]

[Display omitted] Designing heterojunction catalysts with energy effects at the interface, particularly combining the surface structure advantages of super-hydrophilic interfaces with the high activity advantages of bimetal synergistic optimisation, is the key to developing economical and efficient industrial electrocatalytic water-splitting catalysts. In this study, a coupled nanoflower-like NiFe(OH) x /(Ni, Fe)Se heterostructure catalyst supported on Ni foam (NF) (NFSe@NFOH/NF) was designed and successfully prepared using hydrothermal and electrodeposition strategies. Owing to the electron interaction at the heterogeneous amorphous (NFOH)/crystalline (NFSe) interface and the bimetallic synergistic effect of Ni and Fe, the prepared NFSe@NFOH/NF exhibited excellent and stable oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalytic properties, with low overpotentials of 214/276 mV at 100 mA⋅cm−2 and 262/340 mV at 500 mA⋅cm−2. The assembled water electrolyser comprising NFSe@NFOH/NF || NFSe@NFOH/NF needed only small voltages of 1.73 and 1.85 V to yield current densities of 100 and 500 mA⋅cm−2, respectively. This study offers an innovative design idea for the rational adoption of interface engineering and amorphous–crystalline engineering techniques to construct catalysts with excellent catalytic activity and stability for electrocatalytic overall water splitting (EOWS) at a high current density, which further facilitates the advancement of sustainable energy technology in the future. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Electrochemistry is the property of Journal of Electrochemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, in-situ growing of FeNiS x /NiFe(OH) x on nickel form (NF) is successfully realized using a facile corrosion engineering process followed by a fast and mild sulfurization process, and applied as the anode for seawater electrolysis. The obtained anode requires only a low overpotential of 270 mV at a high current density of 100 mA cm−2 in alkaline simulated seawater and maintains mechanical stability at an industrial-level current density of 1 A cm−2 without corrosion. DFT calculations reveals that the FeNiS x /NiFe(OH) x has high selectivity towards oxygen evolution reaction (OER) against chlorine evolution reaction (ClER). For overall seawater electrolysis using it as the bifunctional electrocatalyst, the electrolyzer only requires a low cell voltage of 1.60 V at 10 mA cm−2 and can sustain stable at the industrial-level current density of 1 A/cm2 with a cell voltage of 2.81 V, achieving a high hydrogen productivity without the catalyst deterioration. [Display omitted] • A facile corrosion engineering with a fast and mild sulfurization step is proposed for electrode fabrication. • A bifunctional FeNiS x /NiFe(OH) x electrocatalyst is successfully grown on nickel foam without the use of nickel precursor. • The catalyst exhibits excellent selective performance at a high current density in seawater. • S substitution and Fe active sites are discovered to be the most important factors in catalytic performance. • High H 2 productivity without catalyst deterioration at an industrial-level current density is achieved. [ABSTRACT FROM AUTHOR]

Highlights: The robust organic/inorganic hybrid interlayer derived from in situ formed tribofilms were fabricated by using a scalable rolling method. The interlayer facilitates dendrite-free lithium metal anodes by building local de-solvation environments near the interface and inhibiting both dendrite growth and electrolytes corrosion. The symmetrical cell exhibits a remarkable lifespan of 5,600 h (1.0 mA cm-2 and 1.0 mAh cm-2) and 1,350 cycles even at a harsh condition (18.0 mA cm-2 and 3.0 mAh cm-2). The practical application of Li metal anodes (LMAs) is limited by uncontrolled dendrite growth and side reactions. Herein, we propose a new friction-induced strategy to produce high-performance thin Li anode (Li@CFO). By virtue of the in situ friction reaction between fluoropolymer grease and Li strips during rolling, a robust organic/inorganic hybrid interlayer (lithiophilic LiF/LiC6 framework hybridized -CF2-O-CF2- chains) was formed atop Li metal. The derived interface contributes to reversible Li plating/stripping behaviors by mitigating side reactions and decreasing the solvation degree at the interface. The Li@CFO||Li@CFO symmetrical cell exhibits a remarkable lifespan for 5,600 h (1.0 mA cm−2 and 1.0 mAh cm−2) and 1,350 cycles even at a harsh condition (18.0 mA cm−2 and 3.0 mAh cm−2). When paired with high-loading LiFePO4 cathodes, the full cell lasts over 450 cycles at 1C with a high-capacity retention of 99.9%. This work provides a new friction-induced strategy for producing high-performance thin LMAs. [ABSTRACT FROM AUTHOR]

The focus of this paper is to investigate the practicality of incorporating immersion cooling methods to mitigate the temperature elevation of motors utilized in hybrid aircraft. Air cooling, oil jacket cooling, slot-channel oil cooling and immersion cooling techniques are each applied to a permanent magnet synchronous motor. When a hybrid aircraft is operating, the amount of fuel it carries is limited and decreases over time. In this case, the normal operating time of the motor is investigated in this paper. The study shows that for the motors in this paper, immersion cooling is the most effective with a limited amount of coolant and takes the longest time to reach the upper temperature limit, which can be improved by 5.6 times compared to slot-channel cooling. This paper serves as a reference for the design of motors for hybrid aircraft utilizing immersion cooling technology. [ABSTRACT FROM AUTHOR]

Arsenic is the only beneficial impurity for copper electrorefining through inhibiting anode passivation and the formation of floating slimes. The behaviour of copper anodes with different content of arsenic were studied at high current density (>280 A/m² ). It showed that low arsenic anodes (As < 300 ppm) easily generated anode passivation, floating slimes and cathode nodules during the electrorefining proccess. The floating slimes, electrolyte, cathode and anode were observed and analyzed. As result, low arsenic anodes were more likely to be passivated due to their microstructure defects and irregular microstructure. Increasing electrolyte temperature and addition of glycerol were propitious to reduce low arsenic anodes’ passivation. The floating slimes occured when the concentration of As(III) in electrolyte decreased to 1 g/L, and they would be precipitated by polyacrylamide. All measures greatly improved the cathode quality at current density of 300 A/m2 . [ABSTRACT FROM AUTHOR]

Commercialization of lithium-oxygen batteries faces many challenges, such as electrolyte decomposition, short cycle life, low energy and power density, and high cell mass. However, the commercialization of LiO2 batteries for aeronautics is more challenging due to additional safety constraints on cyclability and performance (high specific-power and specific-energy). In this paper, we perform experiments and use the results to calibrate a 1-D finite element model to simulate discharge profiles up to 5 mA cm-2. The calibrated model is used to perform parametric studies of geometrical, microstructural, transport, and material properties for different discharge times, and discharge current densities. Next, a simulation-based optimization study shows optimal cell designs for various electrolytes for high specific-power. Results show that a high specific-power LiO2 cell needs to have a cathode with a thickness equal to oxygen diffusion length, thin separator, optimized anode, and other components with low mass. The specific-power is sensitive to discharge time, discharge current density, and microstructural and geometrical properties. Also, in some cases, electrolytes with high oxygen solubility or high external partial pressure can compensate for electrolytes with low oxygen diffusivity. However, reducing the cell mass is the most straight forward path to improving specific-power.

Commercialization of lithium-oxygen batteries faces many challenges, such as electrolyte decomposition, short cycle life, low energy and power density, and high cell mass. However, the commercialization of LiO2 batteries for aeronautics is more challenging due to additional safety constraints on cyclability and performance (high specific-power and specific-energy). In this paper, we perform experiments and use the results to calibrate a 1-D finite element model to simulate discharge profiles up to 5 mA cm-2. The calibrated model is used to perform parametric studies of geometrical, microstructural, transport, and material properties for different discharge times, and discharge current densities. Next, a simulation-based optimization study shows optimal cell designs for various electrolytes for high specific-power. Results show that a high specific-power LiO2 cell needs to have a cathode with a thickness equal to oxygen diffusion length, thin separator, optimized anode, and other components with low mass. The specific-power is sensitive to discharge time, discharge current density, and microstructural and geometrical properties. Also, in some cases, electrolytes with high oxygen solubility or high external partial pressure can compensate for electrolytes with low oxygen diffusivity. However, reducing the cell mass is the most straight forward path to improving specific-power.

ABSTRACTAs an important part of water splitting, the oxygen evolution reaction (OER) requires efficient, low-cost, and stable catalysts to overcome its sluggish kinetic barrier. In this study, based on previously reported OER catalyst materials of boron monosulfide mixed with graphene (r-BS+G), nickel foam (NF) is introduced as a supporting material for an r-BS+G electrocatalyst. The resulting r-BS+G-NF exhibits a very low overpotential at 10 (245 mV), 100 (308 mV), and 500 (405 mV) mA cm−2, with a low Tafel slope (56 mV dec−1). In addition, r-BS+G-NF exhibits high durability and can maintain high activity for more than 100 h at 100 mA cm−2. This is in sharp contrast to the catalyst without graphene (r-BS+NF), which shows lower durability. The results suggest that the unique morphology of the NF provides a large electrochemically active area and exposes more active sites on the surface of the prepared electrocatalyst, while the flexible graphene sheets play an important role as a support for effectively combining r-BS and NF. Consequently, the self-supporting structure can improve the OER performance as well as stability. Therefore, this study provides a promising strategy for use as an efficient and stable OER catalyst at high current densities.

Inductive loops at low frequencies have been observed in the electrochemical impedance spectra (EIS) of various electrochemical cells. Although different physicochemical models for this phenomenon have been suggested in many other applications, this topic has not been widely discussed in the field of proton exchange membrane (PEM) electrolysis.In this article, low-frequency inductive loops in PEM electrolysis cells and their impact on cell performance are analyzed. We show that this phenomenon is reproducible and occurs with different cell materials and setups. Its impact increases with increasing current density and decreasing temperature. At extreme conditions (7 A∙cm−2, 40 °C) we show that the negative polarization resistance of the inductive process can exceed the capacitive polarization processes by a factor of three, resulting in a direct current resistance less than the high frequency series resistance of the cell.

Electrochemical water splitting is a promising approach for producing sustainable and clean hydrogen. Typically, high valence state sites are favorable for oxidation evolution reaction (OER), while low valence states can facilitate hydrogen evolution reaction (HER). However, here we proposed a high valence state of Co3+ in Ni9.5Co0.5−S−FeOx hybrid as the favorable center for efficient and stable HER, while structural analogues with low chemical states showed much worse performance. As a result, the Ni9.5Co0.5−S−FeOx catalyst could drive alkaline HER with an ultra‐low overpotential of 22 mV for 10 mA cm−2, and 175 mV for 1000 mA cm−2 at the industrial temperature of 60 °C, with an excellent stability over 300 h. Moreover, this material could work for both OER and HER, with a low cell voltage being 1.730 V to achieve 1000 mA cm−2 for overall water splitting at 60 °C. X‐ray absorption spectroscopy (XAS) clearly identified the high valence Co3+ sites, while in situ XAS during HER and theoretical calculations revealed the favorable electron capture at Co3+ and suitable H adsorption/desorption energy around Co3+, which could accelerate the HER. The understanding of high valence states to drive reductive reactions may pave the way for the rational design of energy‐related catalysts. [ABSTRACT FROM AUTHOR]

Alkaline water electrolysis provides a promising route for "green hydrogen" generation, where anodic oxygen evolution reaction (OER) plays a crucial role in coupling with cathodic hydrogen evolution reaction. To date, the development of highly active and durable OER catalysts based on earth‐abundant elements has drawn wide attention; nevertheless, their performance under high current densities (HCDs ≥1000 mA cm−2) has been less emphasized. This situation has seriously impeded large‐scale electrolysis industrialization. In this review, in order to provide a guideline for designing high‐performance OER electrocatalysts, the effects of HCD on catalytic performance involving electron transfer, mass transfer, and physical/chemical stability are summarized. Furthermore, the design principles were pointed out for obtaining efficient and robust OER electrocatalysts in light of recent progress of OER electrocatalysts working above 1000 mA cm−2. These include the aspects of developing self‐supported catalytic electrodes, enhancing intrinsic activity, enhancing the catalyst–support interaction, engineering surface wettability, and introducing protective layer. Finally, summaries and outlooks in achieving OER at industrially relevant HCDs are proposed. [ABSTRACT FROM AUTHOR]

Electrochemical oxygen evolution reaction (OER) is hampering the development of hydrogen production on a large scale, accompanied with difficulties in achieving high current density (>1 A cm-2) and poor stability for current catalysts. Herein, the FeCoW hydroxides supported on Ni foam (FeCoW/NF) are synthesized via a simple and controllable electrodeposition method, which deliver the high current density of 1.28 A cm-2 at the 770-mV overpotential vs reversible hydrogen electrode (RHE), together with steady operation at 100 mA cm-2 for 100 h in 1 M KOH. Moreover, the as-prepared FeCoW/NF electrocatalyst possesses an ultralow overpotential of 360 mV vs RHE to drive oxygen evolution reaction for the current density of 100 mA cm-2, outperforming most current transition metal-based catalysts. This work enables opportunities in exploring promising paths to achieve non-noble electrocatalysts for scale-up water spitting at industrial current. [Display omitted] • Synthesize FeCoW hydroxides via facile one-step electrodeposition. • Exhibit overpotential of 300 mV to reach 10 mA cm−2 for OER. • Achieve high current activity of 1 A cm−2 at ultralow overpotential of 650 mV. • Operate 100 h at 100 mA cm−2 with negligible attenuation. [ABSTRACT FROM AUTHOR]

Bifunctional electrocatalysts with superior activity and durability are of great importance for electrocatalytic water splitting. Herein, hierarchical structured CoO/CoP heterojunctions are successfully designed as highly efficient and freestanding bifunctional electrocatalysts toward overall water splitting. The unique microstructure combining two‐dimensional nanosheets with one‐dimensional nanowires enables numerous exposed active sites, shortened ion‐diffusion pathways, and enhanced conductivity, significantly improving performance. Such freestanding electrodes achieve high current density over 400 mA cm−2 at low overpotentials and have exceptional electrocatalytic activity as well as long‐term durability for both hydrogen and oxygen evolution reactions under alkaline conditions. Remarkably, a high current density of 20 mA cm−2 is generated at a low cell voltage of 1.56 V in an alkaline water electrolyzer, originating from synergistic interactions between CoO and CoP exposing active sites and facilitating charge transfer and enhancing kinetics. This work provides new insight into designing low‐cost but high‐performance bifunctional electrocatalysts for practical water splitting. [ABSTRACT FROM AUTHOR]

Members of transition metal dichalcogenides, particularly molybdenum disulfide, have been recognized as promising efficient and durable earth‐abundant catalysts for the hydrogen evolution reaction (HER). Despite the recent significant progress, the HER performance of MoS2 is still far from satisfactory, especially at high current densities. Here, a simultaneous multilevel structural control strategy is reported to cooperatively boost hydrogen evolution on 2H‐MoS2, unlocking its potential for practical hydrogen evolution at ampere‐level current densities. By confining the epitaxial growth of few‐layered, curved MoS2 nanosheets within a tubular mesoporous graphitic framework, one can achieve deliberate structural control of MoS2 across seven orders of magnitude on the length scale. The resulting MoS2@C supertubes, benefiting from their unique structural features across atomic‐to‐microscopic scales, are characterized by abundant edge sites and sulfur vacancies, facilitated charge and mass transport, and rapid gas bubble removal. As a consequence, such MoS2@C supertubes exhibit exceptional high‐current‐density HER activity surpassing previously reported 2H‐MoS2 catalysts and even commercial Pt/C catalysts. This work demonstrates the validity of multilevel structural engineering of 2H‐MoS2 by confinement growth, opening a viable route of developing low‐cost catalysts toward practical hydrogen evolution. [ABSTRACT FROM AUTHOR]

Searching for efficient, stable and low-cost nonprecious catalysts for oxygen and hydrogen evolution reactions (OER and HER) is highly desired in overall water splitting (OWS). Herein, presented is a nickel foam (NF)-supported MoS 2 /NiFeS 2 heterostructure, as an efficient electrocatalyst for OER, HER and OWS. The MoS 2 /NiFeS 2 /NF catalyst achieves a 500 mA cm−2 current density at a small overpotential of 303 mV for OER, and 228 mV for HER. Assembled as an electrolyzer for OWS, such a MoS 2 /NiFeS 2 /NF heterostructure catalyst shows a quite low cell voltage (≈1.79 V) at 500 mA cm−2, which is among the best values of current non-noble metal electrocatalysts. Even at the extremely large current density of 1000 mA cm−2, the MoS 2 /NiFeS 2 /NF catalyst presents low overpotentials of 314 and 253 mV for OER and HER, respectively. Furthermore, MoS 2 /NiFeS 2 /NF shows a ceaseless durability over 25 h with almost no change in the cell voltage. The superior catalytic activity and stability at large current densities (>500 mA cm−2) far exceed the benchmark RuO 2 and Pt/C catalysts. This work sheds a new light on the development of highly active and stable nonprecious electrocatalysts for industrial water electrolysis. [Display omitted] • MoS 2 /NiFeS 2 /NF shows ultrahigh activity for OER and HER at large current density. • Ultralow overpotentials (η 1000, OER = 314 mV, η 1000, HER = 254 mV) are needed. • MoS 2 /NiFeS 2 /NF exhibits ultralow cell voltage of 1.79 V@500 mA/cm2 for OWS. • The catalyst shows high stability with no decay in the CP test for OWS over 25 h. [ABSTRACT FROM AUTHOR]

Hydrogen, carrying a high energy density and emitting zero greenhouse gases when in use, is particularly promising as an alternative for traditional fossil fuels. Electrochemical water splitting is an economical technology for producing sustainable and high-purity hydrogen gas. However, the intrinsically sluggish kinetics of the anode oxygen evolution reaction (OER) always decreases the efficiency of hydrogen production; the development of highly active and durable electrocatalysts with improved OER kinetics is thus desirable and crucial. Herein, Fe-based metal–organic framework (MOF)-Ni3S2 heterostructure nanocomposites are synthesized on a nickel foam (NF) substrate. The self-supporting Fe MOF-Ni3S2/NF catalyst shows excellent catalytic activities for OER. In alkaline media (1.0 M KOH), only 243 mV of overpotential is needed to reach the current density of 100 mA·cm–2. Even at the commercially viable high current densities of 500 and 1000 mA·cm–2, ultralow overpotentials of 283 and 309 mV are required, respectively. The catalytic activity of Fe MOF-Ni3S2/NF far exceeds that of the noble metal catalysts (e.g., RuO2) and most non-noble metal OER catalysts reported in the literature. In addition, the Fe MOF-Ni3S2/NF nanocomposite exhibits ultrahigh long-term stability at high current densities, with almost no activity attenuation in the chronopotentiometry test conducted at 100 mA·cm–2 and a negligible attenuation (23 mV) at 500 mA·cm–2 for 20 h. Our findings provide insights into designing and preparing cost-effective, highly active, and durable electrocatalysts for OER at high current densities. [ABSTRACT FROM AUTHOR]

Understanding the stability and current-carrying capacity of graphene spintronic devices is key to their applications in graphene channel-based spin current sensors, spin-torque oscillators, and potential spin-integrated circuits. However, despite the demonstrated high current densities in exfoliated graphene, the current-carrying capacity of large-scale chemical vapor deposited (CVD) graphene is not established. Particularly, the grainy nature of chemical vapor deposited graphene and the presence of a tunnel barrier in CVD graphene spin devices pose questions about the stability of high current electrical spin injection. In this work, we observe that despite structural imperfections, CVD graphene sustains remarkably highest currents of 5.2 × 108 A/cm2, up to two orders higher than previously reported values in multilayer CVD graphene, with the capacity primarily dependent upon the sheet resistance of graphene. Furthermore, we notice a reversible regime, up to which CVD graphene can be operated without degradation with operating currents as high as 108 A/cm2, significantly high and durable over long time of operation with spin valve signals observed up to such high current densities. At the same time, the tunnel barrier resistance can be modified by the application of high currents. Our results demonstrate the robustness of large-scale CVD graphene and bring fresh insights for engineering and harnessing pure spin currents for innovative device applications. [ABSTRACT FROM AUTHOR]

With the further exploitation of renewable energy sources, electrochemical hydrogen evolution reaction (HER) is considered a key technology to solve environmental problems and achieve global carbon neutrality. Currently, alkaline water electrolyzers (AWEs) have been revitalized as a traditional electrolytic water production industry, yet they face great challenges in achieving new technological breakthroughs due to the catalytic properties of electrode materials. In alkaline media, besides the slow kinetics of oxygen evolution reaction, the sluggish HER needing water dissociation and the mass transfer problems at high current densities are among the major factors limiting the development of alkaline water electrolysis for industrial applications. Therefore, it is of great importance to design HER electrocatalysts with high activity and stability at high current densities (>500 mA cm−2) for industrial applications at the “Research and Development level” (R&D level). Herein, a brief overview of the development of AWEs at the industrial scale is presented, and some mainstream recognized catalysis mechanisms for HER in alkaline electrolytes are summarized. Based on the requirements of industrial application and theoretical guidance, the activation strategies of HER electrocatalysts are also summarized. This review will propose new insights into the future development of alkaline water electrolysis.

Developing non-precious metal-based electrocatalysts operating in high-current densities is highly demanded for the industry-level electrochemical hydrogen evolution reaction (HER). Here, we report the facile preparation of binder-free Mo2C-Mo2N heterostructures on carbon nanowalls/diamond (CNWs/D) via ultrasonic soaking followed by an annealing treatment. The experimental investigations and density functional theory calculations reveal the downshift of the d-band center caused by the heterojunction between Mo2C/Mo2N triggering highly active interfacial sites with a nearly zero ∆GH* value. Furthermore, the 3D-networked CNWs/D, as the current collector, features high electrical conductivity and large surface area, greatly boosting the electron transfer rate of HER occurring on the interfacial sites of Mo2C-Mo2N. Consequently, the self-supporting Mo2C-Mo2N@CNWs/D exhibits significantly low overpotentials of 137.8 and 194.4 mV at high current densities of 500 and 1000 mA/cm2, respectively, in an alkaline solution, which far surpass the benchmark Pt/C (228.5 and 359.3 mV) and are superior to most transition-metal-based materials. This work presents a cost-effective and high-efficiency non-precious metal-based electrocatalyst candidate for the electrochemical hydrogen production industry.

Direct electrolytic splitting of seawater for the production of H2 using ocean energy is a promising technology that can help achieve carbon neutrality. However, owing to the high concentrations of chlorine ions in seawater, the chlorine evolution reaction always competes with the oxygen evolution reaction (OER) at the anode, and chloride corrosion occurs on both the anode and cathode. Thus, effective electrocatalysts with high selectivity toward the OER and excellent resistance to chloride corrosion should be developed. In this critical review, we focus on the prospects of state-of-the-art metal-oxide electrocatalysts, including noble metal oxides, non-noble metal oxides and their compounds, and spinel- and perovskite-type oxides, for seawater splitting. We elucidate their chemical properties, excellent OER selectivity, outstanding anti-chlorine-corrosion performance, and reaction mechanisms. In particular, we review metal oxides that operate at high current densities, near industrial application levels, based on special catalyst design strategies.

A zinc‐bromine redox flow battery (RFB) is highly suitable for high‐energy storage due to its decoupled energy and power generation. However, the poor kinetics and poor reversible behavior of Br2/Br− redox activity are some of the significant barriers, and as a result, the flow system delivers low power density. To increase the efficiency of the flow cell, in the present work, bimetallic catalysts are deposited on 3D graphite felt network and are used in the positive electrode for enhancing the kinetics of the Br2/Br− redox reaction. The platinum–nickel (PtNi) bimetallic composition is optimized, and the highly improved performances are investigated using half‐cell and flow‐cell assembly. The redox kinetics parameters are improved due to the high electro‐catalytic nature of the heat‐treated Ni‐rich PtNi coating on the graphite felt (GF) and the flow cell is operated up to 140 mA cm−2. The flow cell with Pt0.5Ni1@GF delivers an impressive ever‐best power density of around 1550 mW cm−2. The cycle life shows excellent stability up to 300 cycles with coulombic, voltage, and energy efficiency of 97%, 86%, and 83%, respectively. Thus, the present work offers a promising approach to developing effective electrode materials for obtaining a superpower RFB system. [ABSTRACT FROM AUTHOR]

Hydrogen generated in electrolyzers is discussed as a key element in future energy scenarios, but oxygen evolution as the standard anode reaction is a complex multi‐step reaction requiring a high overpotential. At the same time,it does not add value‐the oxygen is typically released into the atmosphere. Alternative anode reactions which can proceed at similar current densities as the hydrogen evolution are, therefore, of highest interest. We have discovered a high‐performance electrode based on earth‐abundant elements synthesized in the presence of H2O2, which is able to sustain current densities of close to 1 A cm−2 for the oxidation of many organic molecules, which are partly needed at high production volumes. Such anode reactions could generate additional revenue streams, which help to solve one of the most important problems in the transition to renewable energy systems, i.e. the cost of hydrogen electrolysis. [ABSTRACT FROM AUTHOR]

High current density reaching 1 A cm−2 for efficient oxygen evolution reaction (OER) was demonstrated by interactively optimizing electrolyte and electrode at non‐extreme pH levels. Careful electrolyte assessment revealed that the state‐of‐the‐art nickel‐iron oxide electrocatalyst in alkaline solution maintained its high OER performance with a small Tafel slope in K‐carbonate solution at pH 10.5 at 353 K. The OER performance was improved when Cu or Au was introduced into the FeOx‐modified nanostructured Ni electrode as the third element during the preparation of electrode by electrodeposition. The resultant OER achieved 1 A cm−2 at 1.53 V vs. reversible hydrogen electrode (RHE) stably for 90 h, comparable to those in extreme alkaline conditions. Constant Tafel slopes, apparent activation energy, and the same signatures from operando X‐ray absorption spectroscopy among these samples suggested that this improvement seems solely correlated with enhanced electrochemical surface area caused by adding the third element. [ABSTRACT FROM AUTHOR]

[Display omitted] • Super-hydrophilic PNF with hierarchically porous structure was fabricated. • Fe-Ni 3 S 2 /PNF was fabricated via mild and scalable electro-deposition strategies. • Fe-Ni 3 S 2 /PNF shows 10 mA cm−2 at 1.50 V cell voltage for overall water splitting. • Fe-Ni 3 S 2 /PNF shows excellent activity and durability under industrial conditions. Alkaline water electrolysis (AWE) offers a promising route for green hydrogen production. However, its industrial application is impeded by unsatisfactory energy conversion efficiency. Herein, a robust electrode composed of porous nickel foam (PNF) and Fe-doped Ni 3 S 2 (Fe-Ni 3 S 2) nanosheet arrays was fabricated and applied for industrial AWE. By conducting a scalable dynamic bubble-template method, PNF with high loading of active catalysts was prepared. The superhydrophilicity of PNF facilitates bubble detachment and promotes mass transfer, especially at high current densities. In addition, Fe-Ni 3 S 2 with optimized electronic structure is featured with enhanced electrical conductivity, sufficient exposure of active sites, and optimized adsorption of intermediates. Benefiting from the concerted advantages of PNF and Fe-Ni 3 S 2 , the obtained Fe-Ni 3 S 2 /PNF-5 electrode with an optimal Fe content of 5 mol% exhibits high catalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Compared with the Pt/C/NF||IrO 2 /NF couple, the Fe-Ni 3 S 2 /PNF-5||Fe-Ni 3 S 2 /PNF-5 couple delivers a current density of 10 mA cm−2 at a low cell voltage of 1.50 V for AWE. Under industrial conditions, a competitive cell voltage of 1.75 V is needed for achieving a high current density of 400 mA cm−2. Besides, the couple can operate stably for 120 h, outperforming the commercial RN||RN couple. This work provides a novel strategy to elevate the loading amount of catalysts and improve the electrochemical performance of the electrode for practical AWE application. [ABSTRACT FROM AUTHOR]

The development of electrocatalysts toward the hydrogen evolution reaction (HER) with high-current-density capability is critical for the practical application of water splitting for hydrogen production. While Pt-based materials are regarded as the most efficient HER catalysts, they suffer from scarcity and high price. Thus, it is of vital importance to lower the loading of Pt while maintaining high activity. Here, we report the fabrication of a monolithic aligned porous carbon film electrode co-modified with Pt single atoms and Pt nanoclusters (Pt SA/NC-AF) containing ultralow Pt content (0.038 wt.%) via a facile electrochemical deposition process. Benefiting from the aligned porous structure of the carbon film and the high exposure of the Pt species, the optimized Pt SA/NC-AF electrode exhibits outstanding HER performance in 0.5 M H2SO4 with exceptional intrinsic activity (turnover frequency (TOF) = 904.9 s−1 at η = 100 mV) and ultrahigh mass activity (888.6 A·mgPt−1 at · = 100 mV). Further, it can deliver an industrially relevant current density of 1,000 mA·cm−2 at an overpotential as low as 139 mV. This work provides a feasible avenue for the rational design of metal single-atom and nanocluster catalysts and additionally promotes the application of ultralow-loading noble metal-based catalysts in high-rate hydrogen production. [ABSTRACT FROM AUTHOR]

Abstract Rational design and controllable synthesis of practical electrodes with high stability and activity at high current density for a hydrogen evolution reaction (HER) are critical for renewable and sustainable energy conversion. However, high‐performance TiO2‐based electrocatalysts for HER are quite limited, and the catalytic active centers still remain elusive. Herein, a simple strategy is demonstrated for the synthesis of TiO2–carbon composite (TiO2/C) with high HER performance and stability. The remarkable HER performance of TiO2/C can be ascribed to the doping of carbon atoms, which leads to stronger hybridization of Ti 3d and O 2p orbitals, thus substantially improving the electrocatalytic efficiency. This study elucidates that the hydrogen evolution activity of oxide electrocatalysts can be largely improved by regulating their electronic structures by doping carbon atoms and also provides an effective strategy for designing heterostructured electrocatalysts with high catalytic activity and stability at high current density for HER.

To increase the specific capacity and cycle stability of lithium-ion batteries at high current density, we have investigated the anode materials. Among them, black phosphorus has attracted attention because of its large theoretical specific capacity (2596 mA h/g). However, the moderate conductivity of black phosphorus itself makes it less effective. The addition of graphite to form P-C and P-O-C bonds with black phosphorus enhances the performance of the battery cell. Lithium ions are primarily stored in black phosphorus-graphite layered structural materials via an intercalation mechanism, which improves electrochemical performance at tiny current density but is inadequate for charge/discharge cycling at high current density. In addition, lithium ions also can undergo conversion mechanism with metal oxide materials (e.g. Tungsten trioxide). While this conversion mechanism enables more stable battery cycling at high current density, the specific capacity remains insufficiently high. Higher charge/discharge specific capacity and long cycle stability of lithium-ion batteries at high current density can be realized by the joint action of the two mechanisms. In this work, black phosphorus, graphite, and tungsten trioxide (BP/G/WO 3) composites are prepared by ball milling method. A comprehensive series of electrochemical analyses reveals that the BP/G/WO 3 -532 electrode (BP, graphite, and WO 3 mass ratio of 5:3:2) exhibits the most substantial enhancement in the cycling stability of lithium-ion batteries. The anode exhibits a high specific capacity of 1463.1 mA h/g at 6 A/g and presents a retention capacity of 1159.8 mA h/g after 300 charge/discharge cycles, indicating a high cycle stability and fast reaction kinetics. This result is mainly attributed to the joint action of two mechanisms of composites. • A composite electrode possesses both intercalation and conversion mechanisms. • BP is connected to graphite through stable chemical bonds. • Capacity decay rate is only 4 % when current density raised from 6 A/g to 8 A/g. • A high specific capacity of 1463.1 mA h/g is achieved at 6 A/g. [ABSTRACT FROM AUTHOR]

The construction of an ex-situ artificial solid electrolyte interphase (SEI) layer has been recognized as a viable solution to address the limitation of sodium metal anode (SMA). However, most artificial SEI layers are generated by a single element (i.e. Na-halides, Na-phosphides, or Na-chalcogenides) limiting the lifespans of SMA. To further enhance the cyclic stability and mechanical strength, a multicomponent interphase layer composed of Na 2 Se, Mn metal, and Zn metal (i.e. Na 2 Se/MZ) on the surface of Na is proposed. This unique hybrid interphase layer is spontaneously produced via chemical reaction during the rolling/folding of binary metal selenides (MnSe/ZnSe@C) with Na metal. In the Na 2 Se/MZ protective layer, Na 2 Se enables fast Na transport, Mn atoms further enhance mechanical strength. Specifically, the Zn atoms make an alloy with Na (NaZn 13) during the initial deposition of Na which further provides sodiophilic nucleation sites. Compared with artificial interphase layers (Na 2 Se/M or Na 2 Se/Z) generated by single metal selenides, the Na||Na symmetric cells with multicomponent protected layers demonstrate exceptional extended cycling life of 8000 h and 1200 h at 1 mA cm−2 and 4 mA cm−2, respectively. Na@Na 2 Se/MZ=|NVP full cells also demonstrate an extended cycling life of 2300 cycles at 15 C with 78 % capacity retention and a high-rate capacity of >60 mAh g−1 at 30 C. Our findings open the path for realizing high capacity and fast-charging SMBs. [Display omitted] • A multicomponent interphase layer composed of Na 2 Se, Mn metal, and Zn metal (Na 2 Se/MZ) on the surface of Na is proposed. • Zn atoms form an alloy with Na metal (NaZn 13) during initial plating and provide abundant nucleation sites. • Mn atoms provide high tensile strength to the protective layer, resulting in control of the volume expansion. • The Na 2 Se component in the interphase layer effectively improves Na+ diffusion kinetics enabling stable Na desposition. • The optimized Na/Na 2 Se/MZ electrodes presented superior electrochemical performances in both symmetric and full cells. [ABSTRACT FROM AUTHOR]

Ce-doped NiO catalyst supported on MoO₂ nanorods (Ce-NiO@MoO₂) was constructed as a high-performance oxygen evolution reaction (OER) electrocatalyst. The introduction of Ce induced the formation of nanoflower-like NiO on the MoO₂ nanorod substrate. Ce doping not only created numerous unsaturated Ni coordination sites with higher oxidation states, serving as active sites, but also strengthened the adsorption of oxygen intermediates by upshifting the Ni 3d band center, thereby reducing the energy barrier of the rate-determining OH* → O* step. Consequently, the Ce-NiO@MoO₂ catalyst exhibited remarkable OER activity, with a low overpotential of 313 mV and outstanding 200-hour stability at 1000 mA cm⁻², which is attributed to unsaturated Ni active sites and promoted charge and mass transfer facilitated by the unique hierarchical structure. These findings highlight the crucial role of Ce doping in improving electrocatalytic performance and offer insights into developing efficient and cost-effective catalysts for large-scale hydrogen production via water electrolysis. [Display omitted] • Ce-NiO@MoO 2 showed excellent OER activity with a low overpotential of 313 mV and outstanding 200-hour stability at 1000 mA cm−2. • Ce doping created numerous unsaturated Ni sites with high OER activity and facilitated Ni2+ to Ni3+ transition. • Ce doping and oxygen vacancies strengthened the adsorption of oxygen intermediates by upshifting the Ni 3d band center. • The hierarchical core-shell structure and low RDS energy barrier synergistically enhanced OER activity at 1000 mA cm−2. [ABSTRACT FROM AUTHOR]

Exploring earth-abundant electrocatalysts to replace platinum/iridium for acidic overall water splitting at high current density is an important challenge towards lowering the cost of green hydrogen production. Herein, we developed a new class of three-dimensional interconnected nanofibers (NFs) composed of ultra-small Ni-doped Co 3 O 4 nanoparticles (Ni-Co 3 O 4 NFs). Benefiting from the unique ultra-small Ni-doped Co 3 O 4 composition and three-dimensional interconnected porous structure, 13.4 % Ni-Co 3 O 4 NFs (Ni doping is 13.4 wt%) exhibits remarkable electrocatalytic performance in acidic media. Specially, in strongly acidic environments, high activity and high stability overall water splitting can be achieved at high current density. As evidenced by the fact that a voltage of 500 mA cm−2 can be achieved at only 1.86 V and operational stability can be maintained at 500 mA cm−2 for 100 h. [Display omitted] • We develop a new class of 3D interconnected nanofibers composed of ultra-small Ni-doped Co 3 O 4 nanoparticles. • Benefiting from the unique structural, 13.4 % Ni-Co 3 O 4 NFs exhibits remarkable HER and OER performance in acidic media. • 13.4 % Ni-Co 3 O 4 NFs exhibits highly active and stable overall water splitting at acidic high current density. • DFT calculations show that the doping of Ni optimizes the electronic structure of Co and prevents the dissolution of Co. [ABSTRACT FROM AUTHOR]

Electrocatalysts play a crucial role in energy production and chemical oxidation. Nonetheless, the efficacy of catalysts in expediting reactions is notably affected by the escape of bubbles and the re-exposure of active sites, particularly under high-current-density conditions. Herein, parallel-aligned Ni(OH) 2 nanosheets array is anchored on nickel foam as substrate to verify mass transfer enhancement theory. Compare with disordered and interconnected nanosheets structures, parallel alignment of nanosheets array with superior mass transfer capability, larger exposed surface area, and spatial confinement effects is demonstrated to boost effective removal of in situ generated gas bubbles. Moreover, carbon coating layer with high electrical conductivity and nickel-iron-based composite with high activity is simultaneously anchored on parallel-aligned nanosheets surface (C@FeNi/NF-P). As illustration of application viability, C@FeNi/NF-P exhibits overpotential of 317 mV and potential of 1.45 V at 500 mA cm−2, respectively, for oxygen evolution (OER) and urea oxidation (UOR) with good stability. Moreover, the mass transfer enhancement effect of parallel aligned structure for the high active electrodes is also discussed. This work provides new insight for physical structural modulation of active materials to strengthen electrocatalytic activity with high mass-transfer efficiency, further ensuring high-efficient and stable water splitting and urea oxidation. [Display omitted] • The parallel-aligned nanosheets arrays is fabricated by lattice matching growth. • Open and confined structure can promote bubbles release and active sites exposure. • Carbon layer and Fe-dopant are introduced to enhance conductivity and activity. • Superior OER and UOR activity can be achieved at 500 mA cm−2 with high stability. • Structure alignment of active materials plays universal role in activity modulation. [ABSTRACT FROM AUTHOR]

Iron-based materials have been extensively studied and applied as electrocatalysts. However, the electronic structure of iron itself is not conducive to effectively activating adsorbed intermediates, leading to slower kinetic steps. In this study, a heterogeneous composite catalyst with a nano-sheet array structure consisting of iron boron/sulfide (FeS@Fe 2 B/IP) was successfully prepared through a two-step process involving boriding and sulfidation of iron plates. The nanosheet array structure provides numerous catalytic active sites, promotes effective contact between electrolytes and catalytic sites, and enhances the apparent reaction rate of the catalyst. Additionally, the heterogeneous interface of FeS/Fe 2 B plays a crucial role in regulating the electronic structure of the metal Fe site, improving charge transfer rates, and accelerating electrocatalytic reaction kinetics. Ultimately, FeS@Fe 2 B/IP demonstrates outstanding water splitting performance, with only 177 and 191 mV overpotential providing 10 mA cm−2 toward HER and OER, respectively. Furthermore, it achieves a high current density of 500 mA cm−2 at 473 and 520 mV overpotentials for HER and OER, respectively. In addition to its excellent performance in water splitting applications, a bipolar alkaline cell was constructed using the FeS@Fe 2 B/IP bifunctional catalyst. This achieved current densities of 10 and 100 mA cm−2 at potentials of 1.63 and 1.75 V. Moreover, the catalytic stability of the FeS@Fe 2 B/IP system remained consistent for nearly 50 hours at current densities of 10 and 100 mA cm−2. These results confirm that FeS@Fe 2 B/IP is indeed a high-performance bifunctional electrocatalytic material which can significantly improve energy utilization efficiency in various applications. [Display omitted] ● A heterogeneous composite catalyst composed of iron-based boride/sulfide with nanosheet array structure was constructed. ● The material showed good catalytic activity and significant catalytic stability against HER and OER. ● The nanosheets provide a higher specific surface area and abundant active sites, which improves the charge transfer rate. ● The heterogeneous interfacial regulates the electron structure of the Fe site and ultimately enhances the intrinsic activity. [ABSTRACT FROM AUTHOR]

• The effects of PTFE layout on mass and charge transport are investigated in detail. • The micropore volume fraction is increased with adding PTFE to enhance liquid water transport. • Increasing gradient in PTFE content is beneficial for alleviating water flooding. • The peak power density can be improved by 33.6 % with optimized PTFE distribution. A coupled experimental and numerical study is undertaken to elucidate the fundamental effects of polytetrafluoroethylene (PTFE) distribution within the anode catalyst layer on transport phenomena and electrochemical performance of anion exchange membrane fuel cells (AEMFCs). A comprehensive multiphysics model is developed to optimize the layout and content of PTFE, guiding the preparation of high-performance multilayer electrodes. We find that a non-gradient PTFE distribution at 10 wt% content achieves a tradeoff between mass transport and charge transport. The optimized gradient distribution of PTFE is observed to further mitigate water flooding without increasing ohmic impedance, enhancing peak power density by 213.6 mW/cm² and cell voltage by 163 mV at 2,000 mA/cm², compared to the membrane electrode assembly without PTFE. These electrochemical performance enhancements are validated with experimental polarization curves. Furthermore, the influence of PTFE layout on mass transport behavior is identified through electrochemical impedance spectroscopy and mercury intrusion porosimetry, revealing that adding PTFE binder to the catalyst layer enhances liquid water transport. This comprehensive study offers vital insights and pragmatic guidelines for designing gradient electrode structures in AEMFCs under high current density conditions, facilitating the development of more efficient and robust fuel cell technologies. [ABSTRACT FROM AUTHOR]

Abstract A zinc‐bromine redox flow battery (RFB) is highly suitable for high‐energy storage due to its decoupled energy and power generation. However, the poor kinetics and poor reversible behavior of Br2/Br− redox activity are some of the significant barriers, and as a result, the flow system delivers low power density. To increase the efficiency of the flow cell, in the present work, bimetallic catalysts are deposited on 3D graphite felt network and are used in the positive electrode for enhancing the kinetics of the Br2/Br− redox reaction. The platinum–nickel (PtNi) bimetallic composition is optimized, and the highly improved performances are investigated using half‐cell and flow‐cell assembly. The redox kinetics parameters are improved due to the high electro‐catalytic nature of the heat‐treated Ni‐rich PtNi coating on the graphite felt (GF) and the flow cell is operated up to 140 mA cm−2. The flow cell with Pt0.5Ni1@GF delivers an impressive ever‐best power density of around 1550 mW cm−2. The cycle life shows excellent stability up to 300 cycles with coulombic, voltage, and energy efficiency of 97%, 86%, and 83%, respectively. Thus, the present work offers a promising approach to developing effective electrode materials for obtaining a superpower RFB system.