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Abstract The development of efficient and stable bifunctional catalysts to meet overall water splitting at high current densities is attractive, but also challenging. Here, a simple one‐step chloride ion etching method to in situ synthesis of platinum (Pt) clusters anchored on amorphous nickel molybdenum hydroxide/nickel foam nanosheets (Pt‐NiMo‐OH/NF) at room temperature is used. Pt‐NiMo‐OH/NF has better catalytic activity for hydrogen evolution and oxygen evolution (OER) than Pt/C/NF and RuO2/NF. The overall water splitting required only 1.83 V versus RHE to reach 1000 mA cm−2, and showed good stability and catalytic activity in 160 h. The excellent catalytic performance and stability of Pt‐MiMo‐OH/NF may be due to the collaborative electron transfer between Pt and amorphous NiMo‐OH leads to an increase in the electron density of Pt clusters, which optimizes the binding energy of Pt and H. At the same time, it induces the formation of high‐valence Ni and Mo, thereby promoting the dissociation of water and the production of OER active substances. This work provides a novel strategy for the synthesis of water splitting catalysts at high current density.

The exploration of non-noble metal-based electro-catalysts to catalyze oxygen evolution reaction (OER) is imperative in sustainable energy development technology. Herein, the validation of improved electro-catalytic performance of an amorphous Al2O3-added Co3O4/NiO nanocomposite toward OER has been reported. Co3O4/NiO nanocomposite, 10%, 20% and 40% of amorphous Al2O3-added Co3O4/NiO nanocomposites were synthesized via a simple nitrate–citrate decomposition method. The experimental results evidenced that the 20% amorphous Al2O3-added Co3O4/NiO nanocomposite exhibits enhanced OER performance where the current density of 50 mA cm−2 is achieved at 389 mV, demonstrating 448 mV improvement as compared to the amorphous Al2O3 free Co3O4/NiO nanocomposite. Double-layer capacitance results reveal that the enhanced OER performance, in case of 20% amorphous Al2O3-modified Co3O4/NiO nanocomposite, results ~ 3.5 times increased electrochemically active surface area. This work suggests that the addition of optimum amount of amorphous Al2O3 to the Co3O4/NiO nanocomposite offers an attractive cost-effective catalyst for water-splitting devices. [ABSTRACT FROM AUTHOR]

Uncontrollable lithium dendrite growth and severe Li/electrolyte side reactions under high operating current densities seriously hinder the development of high‐performance Li metal batteries (LMBs). To address the aforementioned critical issues, spherical Li nuclei are designed via an "all‐in‐one" nitrocellulose (NC)/LiFSI electrolyte to achieve high‐energy/power‐density and long‐cycle LMBs. First, the synergistic effect of LiFSI induced LiF‐rich interface and the nitro group in the NC scaffold promote uniform Li nucleation, resulting in spherical nuclei morphology instead of dendritic even under high current densities. Moreover, NC exhibits strong adsorption energy on the electrode surface, which facilitates the formation of an organic protection layer to suppress side reactions, which enables highly reversible Li cycling, even in a lean‐electrolyte environment. With the assistance of the unique interphase, the Li|Li symmetric cells using NC/LiFSI electrolyte can stably run at a high current density of 10 mA cm‐2. Moreover, the assembled Li|LiFePO4 pouch cell achieves excellent cycling stability of 210 cycles with 100% capacity retention. This finding provides a new strategy relying on electrolyte engineering to achieve high‐energy/power‐density and long‐cycling‐life LMBs. [ABSTRACT FROM AUTHOR]

Anode support is prepared using phase inversion method and directly used for anode supported solid oxide fuel cell. The anode substrate is about 560 µm in thickness and has a porosity of 60.0%. The finger-like pore layer is 522 µm in thickness, in which the finger-like pore diameter is about 30 µm. The sponge layer is 28 µm in thickness and has a porosity of 46.1%. The single cell with Ni-YSZ/YSZ/GDC/BaCo0.4Fe0.4Zr0.1Y0.1O3−δ configuration is fabricated with YSZ electrolyte on the skin layer. At 800°C and under an output voltage of 0.64 V, the single cell attains a power density of 3.33 W cm−2. At 700°C, 750°C and 800°C, the single cell outputs a current density over 5.2 A cm−2 without the appearance of limited current density from gas transport. The results depict gas transport in the anode substrate with the sponge layer and the skin layer is highly efficient.

Herein, we propose a platinization strategy for the preparation of Pt/X catalysts with low Pt content on substrates possessing electron-rich sites (Pt/X: X = Co 3 O 4 , NiO, CeO 2 , Covalent Organic Framework (COF), etc.). In examples with inorganic and organic substrates, respectively, Pt/Co 3 O 4 possesses remarkable catalytic ability toward HER, achieving a current density at an overpotential of 500 mV that is 3.22 times higher than that of commercial Pt/C. It was also confirmed by using operando Raman spectroscopy that the enhancement of catalytic activity was achieved after platinization of the COF, with a reduction of overpotential from 231 to 23 mV at 10 mA cm -2 . Density functional theory (DFT) reveals that the improved catalytic activity of Pt/Co 3 O 4 and Pt/COF originated from the re-modulation of Pt δ+ on the electronic structure and the synergistic effect of the interfacial Pt δ+ /electron-rich sites. This work provides a rapid synthesis strategy for the synthesis of low-content Pt catalysts for electrocatalytic hydrogen production.

LiNi 0.8 Mn 0.1 Co 0.1 O 2 with high nickel content plays a critical role in enabling lithium metal batteries (LMBs) to achieve high specific energy density, making them a prominent choice for electric vehicles (EVs). However, ensuring the long-term cycling stability of the cathode electrolyte interfaces (CEIs), particularly at fast-charge conditions, remains an unsolved challenge. The decay mechanism associated with CEIs and electrolytes in LMB at high current densities is still not fully understood. To address this issue, in situ Fourier transform infrared (FTIR) is employed to observe the dynamic process of formation/disappearance/regeneration of CEIs during charge and discharge cycles. These dynamic processes further exacerbate the instability of CEIs as current density increases, leading to rupture and dissolution of CEIs and subsequent deterioration in battery performance because of continuous electrolyte reactions. Additionally, the dynamic changes occurring within individual components of CEIs at different cycling stages and various current densities are also discussed. The results demonstrate that excellent capacity retention at small current density is attributed to enrichment of inorganic compounds (Li 2 CO 3 , LiF, etc.) and rendering better stability and smaller expansion of CEIs. The key to achieving excellent electrochemical performance at high current densities lies on protecting CEIs, mainly inorganic components., (© 2024 Wiley‐VCH GmbH.)

Producing green hydrogen in a cost-competitive manner via water electrolysis will make the long-held dream of hydrogen economy a reality. Although platinum (Pt)-based catalysts show good performance toward hydrogen evolution reaction (HER), the high cost and scarce abundance challenge their economic viability and sustainability. Here, a non-Pt, high-performance electrocatalyst for HER achieved by engineering high fractions of stacking fault (SF) defects for MoNi 4 /MoO 2 nanosheets (d-MoNi) through a combined chemical and thermal reduction strategy is shown. The d-MoNi catalyst offers ultralow overpotentials of 78 and 121 mV for HER at current densities of 500 and 1000 mA cm -2 in 1 M KOH, respectively. The defect-rich d-MoNi exhibits four times higher turnover frequency than the benchmark 20% Pt/C, together with its excellent durability (> 100 h), making it one of the best-performing non-Pt catalysts for HER. The experimental and theoretical results reveal that the abundant SFs in d-MoNi induce a compressive strain, decreasing the proton adsorption energy and promoting the associated combination of *H into hydrogen and molecular hydrogen desorption, enhancing the HER performance. This work provides a new synthetic route to engineer defective metal and metal alloy electrocatalysts for emerging electrochemical energy conversion and storage applications., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

In recent years, ceramic cells based on high proton conductivity have attracted much attention and can be employed for hydrogen production and electricity generation, especially at low temperatures. Nevertheless, attaining a high power output and durability is challenging, especially at low operational temperatures. In this regard, we design semiconductor heterostructure SFT-ZnO (SrFe 0.3 TiO 3 -ZnO) materials to function as an electrolyte for fuel cell and electrolysis applications. Using this approach, the functional semiconductor heterostructure can deliver a better power output and high ionic and proton conductivity at low operational temperatures. The prepared cell in fuel cell mode has demonstrated excellent performance of 700 mW cm -2 and proton performance of 540 mW cm -2 at the low temperature of 520 °C, suggesting dominant proton conduction. Further, the prepared cell delivers exceptional current densities of 1.18 and 0.38 A cm -2 (at 1.6 and 1.3 V, respectively) at 520 °C in the electrolysis mode. Our electrochemical cell is stable in fuel and electrolysis mode at a low temperature of 500 °C.

Developing catalysts with suitable adsorption energy for oxygen-containing intermediates and elucidating their internal structure-performance relationships are essential for the commercialization of Li-O 2 batteries (LOBs), especially under high current densities. Herein, NiCo 2 O 4 -CeO 2 heterostructure with a spontaneous built-in electric field (BIEF) is designed and utilized as a cathode catalyst for LOBs at high current density. The driving mechanism of electron pumping/accumulation at heterointerface is studied via experiments and density functional theory (DFT) calculations, elucidating the growth mechanism of discharge products. The results show that BIEF induced by work function difference optimizes the affinity for LiO 2 and promotes the formation of nano-flocculent Li 2 O 2 , thus improving LOBs performance at high current density. Specifically, NiCo 2 O 4 -CeO 2 cathode exhibits a large discharge capacity (9546 mAh g -1 at 4000 mA g -1 ) and high stability (>430 cycles at 4000 mA g -1 ), which are better than the majority of previously reported metal-based catalysts. This work provides a new method for tuning the nucleation and decomposition of Li 2 O 2 and inspires the design of ideal catalysts for LOBs to operate at high current density., (© 2024 Wiley‐VCH GmbH.)

Developing single‐atom electrocatalysts with high activity and superior selectivity at a wide potential window for CO2 reduction reaction (CO2RR) still remains a great challenge. Herein, a porous NiNC catalyst containing atomically dispersed NiN4 sites and nanostructured zirconium oxide (ZrO2@Ni‐NC) synthesized via a post‐synthetic coordination coupling carbonization strategy is reported. The as‐prepared ZrO2@Ni‐NC exhibits an initial potential of −0.3 V, maximum CO Faradaic efficiency (F.E.) of 98.6% ± 1.3, and a low Tafel slope of 71.7 mV dec−1 in electrochemical CO2RR. In particular, a wide potential window from −0.7 to −1.4 V with CO F.E. of above 90% on ZrO2@Ni‐NC far exceeds those of recently developed state‐of‐the‐art CO2RR electrocatalysts based on NiN moieties anchored carbon. In a flow cell, ZrO2@Ni‐NC delivers a current density of 200 mA cm−2 with a superior CO selectivity of 96.8% at −1.58 V in a practical scale. A series of designed experiments and structural analyses identify that the isolated NiN4 species act as real active sites to drive the CO2RR reaction and that the nanostructured ZrO2 largely accelerates the protonation process of *CO2− to *COOH intermediate, thus significantly reducing the energy barrier of this rate‐determining step and boosting whole catalytic performance. [ABSTRACT FROM AUTHOR]

Although gel polymer electrolytes (GPEs) have attracted tremendous attention for lithium metal batteries due to their high ionic conductivity, high safety, and excellent adaptability, it is still challenging to suppress the uncontrollable lithium dendrite growth for GPEs. Here, an organic/inorganic composite gel electrolyte (PPPL) as GPEs is proposed, which is formed by ring-opening polymerization reaction of poly(methyl vinyl ether-alt-maleic anhydride) (PMVE-MA) and polyethylene glycol (PEG) in polymer matrix of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) embedded with Li6.4La3Zr1.4Ta0.6O12 (LLZTO) particles. The PMVE-MA participates in the formation of a stable solid electrolyte interface (SEI) and the PEG greatly improves the flexibility of PPPL. The PPPL exhibits excellent performance in terms of a wide electrochemical window (4.7 V), high lithium transference number (0.59), and satisfactory mechanical strength (11 MPa). Besides, the PPPL contributes to the formation of stable and flexible SEI containing organic components and LiF on lithium metal, and constructs fast and uniform lithium transport channels to effectively suppress the lithium dendrite growth. The Li/PPPL/Li symmetric batteries can stably cycle 800 h at the high current density of 5 mA cm-2 and capacity of 5 mAh cm-2. The outstanding electrochemical performance of the PPPL will provide important insights for design of advanced GPEs. [ABSTRACT FROM AUTHOR]

Durable and efficient hydrogen evolution reaction (HER) electrocatalysts that can satisfy industrial requirements need to be developed. Platinum (Pt)‐based catalysts represent the benchmark performance but are less studied for HER under high current densities in neutral electrolytes due to their high cost, poor stability, and extra water dissociation step. Here a facile and low‐temperature synthesis for constructing "blackberry‐shaped" Pt nanocrystals on copper (Cu) foams with low loading as self‐standing electrodes for HER in neutral media is proposed. Optimized hydrogen adsorption free energy and robust interaction induced by charge density exchange between Pt and Cu ensure the efficient and robust HER, especially under high current densities, which are demonstrated from both experimental and theoretical approaches. The electrode exhibits small overpotentials of 35 and 438 mV to reach current densities of ‐10 and ‐1000 mA cm−2, respectively. Meanwhile the electrode illustrates outstanding stability during chronoamperometry measurement under high current densities (‐100 to ‐400 mA cm−2) and 1000 cycles linear sweep voltammetry tests reaching ‐1000 mA cm−2. This study provides new design strategies for self‐standing electrocatalysts by fabricating robust metal–metal interactions between active materials and current collectors, thus facilitating the stable function of electrodes for HER under technologically relevant high current densities. [ABSTRACT FROM AUTHOR]

Water electrolysis is an efficient approach for high-purity hydrogen production. However, the anodic sluggish oxygen evolution reaction (OER) always needs high overpotential and thus brings about superfluous electricity cost of water electrolysis. Therefore, exploiting highly efficient OER electrocatalysts with small overpotential especially at high current density will undoubtedly boost the development of industrial water electrolysis. Herein, we used a simple hydrothermal method to prepare a novel FeOOH–CoS nanocomposite on nickel foam (NF). The as-prepared FeOOH–CoS/NF catalyst displays an excellent OER performance with extremely low overpotentials of 306 and 329 mV at 500 and 1000 mA cm−2 in 1.0 M KOH, respectively. In addition, the FeOOH–CoS/NF catalyst can maintain excellent catalytic stability for more than 50 h, and the OER catalytic activity shows almost no attenuation no matter after 1000 repeated CV cycles or 50 h of stability test. The high catalytic activity and stability have exceeded most non-noble metal electrocatalysts reported in literature, which makes the FeOOH–CoS/NF composite catalyst have promising applications in the industrial water electrolysis. • Nickel foam (NF) supported FeOOH–CoS composite electrocatalyst is synthesized. • FeOOH–CoS/NF shows extremely low overpotential of OER at high current density. • FeOOH–CoS/NF can maintain excellent catalytic stability for more than 50 h. • Our work provides new insights in preparing non-noble metal OER catalysts. [ABSTRACT FROM AUTHOR]

Polymer electrolyte membrane (PEM) fuel cell technology needs to overcome the cost barrier in order to compete with the internal combustion engines (ICEs) for transportation application. A viable approach is to raise fuel cell's power output without increasing its size and Pt loading in the catalyst layers (CLs). In this strategy, the cost per kW power output can be proportionally reduced due to the increased power density. This paper examines this strategy by exploring several important aspects that influence fuel cell performance under high power or current density using a three-dimensional (3-D) fuel cell model. It is shown that local CLs may be subject to low oxygen concentration under a high current density of 2 A/cm2, causing low reaction rate near the outlet, especially under the land. Additionally, the oxygen reduction reaction (ORR) rate may be subject to a large through-plane variation under 2 A/cm2, raising ohmic voltage loss in the CL. Two additional cases are investigated to improve fuel cell performance under 2 A/cm2: one has a 5 times thinner CL with the same ORR kinetics per membrane electrode assembly (MEA) area and the other has a 5 times thinner CL with 5 times higher ORR kinetics. The results show the output voltage is raised approximately from 0.5 V to 0.554 V in the former CL case and further to 0.606 V for the latter CL. To enable high-efficiency operation (e.g. >50%), thinner CLs with high ORR kinetics and GDLs with better transport properties are one research and development (R&D) direction. • Fuel cell operation may subject to oxygen starvation near cathode outlet @ 2.0 A/cm2. • The oxygen reduction reaction (ORR) rate subjects to large spatial variations in all the three dimensions @ 2.0 A/cm2. • GDLs with better transport properties are desirable for high current density operation. • Thinner catalyst layers with high ORR kinetics are desirable for high current density operation. [ABSTRACT FROM AUTHOR]

Hydrogen produced via water electrolysis powered by renewable electricity or green H2 offers new decarbonization pathways. Proton exchange membrane water electrolysis (PEMWE) is a promising technology although the current density, temperature, and H2 pressure of the PEMWE will have to be increased substantially to curtail the cost of green H2. Here, a porous transport layer for PEMWE is reported, that enables operation at up to 6 A cm−2, 90 °C, and 90 bar H2 output pressure. It consists of a Ti porous sintered layer (PSL) on a low‐cost Ti mesh (PSL/mesh‐PTL) by diffusion bonding. This novel approach does not require a flow field in the bipolar plate. When using the mesh‐PTL without PSL, the cell potential increases significantly due to mass transport losses reaching ca. 2.5 V at 2 A cm−2 and 90 °C. On the other hand, the PEMWE with the PSL/mesh‐PTL has the same cell potential but at 6 A cm−2, thus increasing substantially the operation range of the electrolyzer. Extensive physical characterization and pore network simulation demonstrate that the PSL/mesh‐PTL leads to efficient gas/water management in the PEMWE. Finally, the PSL/mesh‐PTL is validated in an industrial size PEMWE in a container operating at 90 bar H2 output pressure. [ABSTRACT FROM AUTHOR]

The strong electronic coupling of NiCo 2 O 4 and CeO 2 promotes the formation/decomposition of Li 2 CO 3. [Display omitted] • Strong electronic coupling effect could promote the formation of membrane-like Li 2 CO 3. • Experiments and DFT results confirmed the Li 2 CO 3 formation is through a surface-adsorption model. • NiCo 2 O 4 /CeO 2 cathode exhibits a good cyclability of 240 cycles at 2000 mA g−1. The sluggish CO 2 reduction/evolution kinetics at the cathode severely hamper the industrial applications of Li–CO 2 batteries, especially under large current densities. Herein, NiCo 2 O 4 /CeO 2 with a strong electron coupling effect is prepared via solvothermal method and calcination to realize the rapid kinetics of discharge and charge processes. The electronic character of the catalyst and the growth behavior of Li 2 CO 3 are investigated through density functional theory (DFT) and experiments, elucidating the reaction mechanism of Li–CO 2 battery. The results demonstrate that the strong electronic coupling of NiCo 2 O 4 and CeO 2 enhances the intrinsic activity of the catalyst and promotes the generation of membrane-like Li 2 CO 3 with good reversibility, thereby enhancing battery performance at a large current density. Consequently, NiCo 2 O 4 /CeO 2 achieved a large specific capacity of 7767 mAh g−1 under 2000 mA g−1 and could be stably cycled more than 240 times, outperforming most reported metal-based catalysts. This work underscores the important role of strong electronic coupling in facilitating the formation and decomposition of Li 2 CO 3 , providing valuable insight for designing cathode catalysts with high-rate properties for Li–CO 2 batteries. [ABSTRACT FROM AUTHOR]

To enhance water management in proton exchange membrane fuel cells, the influence of drying and flooding on performance in different voltage ranges is investigated by experiment. The current density attenuates as the voltage decreases in the concentration polarization range. Through the analysis of the performance curves under different conditions, the performance attenuation is due to the high current and overpotential at low voltage, which leads to the temperature rising and drying up. At high flow rates, the current attenuates at low voltages, indicating that the current density attenuation is not because of flooding and insufficient reactants. According to calculations, the anode water content is low due to more protons and water being transferred from anode toward cathode at the high current, which causes the current density to attenuate. From the current ratio, the cell can generate an additional current density of 3.2% at 0.1 V voltage, which can evaluate the degree of carbon corrosion and water electrolyzation due to the insufficient supply of reactants. In addition, the voltage undershoot of switching to high current is great, and the fuel cell has a high demand for water. Finally, reducing temperature and increasing humidification can alleviate the attenuation of current density. • Current attenuates at high overpotential due to temperature increasing and drying. • Current ratio evaluates carbon corrosion and water electrolysis caused by starvation. • The increase in proton transport at a high current causes the anode to dry up. • Reducing temperature and providing humidification can alleviate the current decrease. [ABSTRACT FROM AUTHOR]

To investigate the effects of di-ions structure of the core layer ionomer on anti-protein fouling and electrodialysis (ED) desalination performance of the tailored anion exchange membranes (AEMs), three highly conductive structural-controlled ionomers containing aliphatic bridging cage quaternary di-ammoniums, aliphatic liner quaternary di-ammoniums, and aromatic quaternary di-ammoniums respectively have been synthesized. With the help of the previously established bi-directional in-situ interpenetration method, a series of double-sided anti-fouling AEMs were successfully fabricated from the gradient cross-linked anti-fouling thin layer CA (2% SA-0.10Ca) and the tailored ionomers. These AEMs have basic and electrochemical properties suitable for ED applications, and significant anti-protein fouling ability. The results of the ED desalination evaluations at high current density with salted egg white confirm further that DABCO-MeI-CA having aliphatic-bridging-cage-di-ions with the best electrochemical properties displays the best ED performance (desalination rate (DR) = 32.16%, energy consumption (EC) = 0.27 kWh kg−1) and good ED stability. Its ED performance is better than that of commercial AMX, with an increase of 20.74% in DR and a reduction of 34.15% in EC. Protein biuret detections verify no protein-through-membrane pollution occurred in the tests. The properties of DABCO-MeI-CA are promising for high current density ED desalination of organic macromolecule-contaminated salted systems. [Display omitted] • Anti-protein fouling AEMs were created by a double-sided interpenetrating method. • Effects of the series-connected di-ions of the ionomers on the AEMs were revealed. • DABCO-MeI-CA with an aliphatic bridging cage ions has strong anti-fouling effect. • The high current ED performance of DABCO-MeI-CA surpasses that of commercial AMX. [ABSTRACT FROM AUTHOR]

Developing highly active and robust transition metal chalcogenides (TMCs) electrocatalysts toward oxygen evolution reaction (OER) remains a challenge. Herein, we report an electron redistribution mechanism that involves the metal-sulfur (M-S) bond stabilization triggered by electron transfer from Ce to Ni and Co in CeO 2 /NiCo 2 S 4 heterostructure, thereby effectively inhibiting the leaching of sulfur from CeO 2 /NiCo 2 S 4 during the OER process. Moreover, the well-modulated heterogeneous interface enables optimal adsorption affinity for oxygen intermediates and reduces the energy barrier of OER. As a result, CeO 2 /NiCo 2 S 4 exhibits superior OER activity with ultralow overpotentials of 146 and 271 mV at 10 and 100 mA cm−2, respectively. More importantly, CeO 2 /NiCo 2 S 4 possesses excellent durability for over 200 h at 500 mA cm−2, surpassing individual NiCo 2 S 4 and most of the reported TMCs-based electrocatalysts. This work provides new insights for achieving good compatibility of TMCs-based OER electrocatalysts in terms of high activity and stability. [Display omitted] A well-modulated CeO 2 /NiCo 2 S 4 heterostructure was successfully constructed. The electron redistribution induced by CeO 2 not only enhanced the formation energy of S vacancies and hindered the reconstruction of NiCo 2 S 4 but also reduced the energy barrier of the OER, ultimately resulting in the CeO 2 /NiCo 2 S 4 catalyst exhibiting excellent activity and stability during the OER process. • CeO 2 /NiCo 2 S 4 achieves with an ultralow overpotential of 146 mV at 10 mA cm−2. • NiCo 2 S 4 extracts electrons from CeO 2 and optimizes interfacial electronic structure. • The introduced CeO 2 reduces the rate-determining step barrier of OER. • The introduction of CeO 2 enhances the formation energy of S vacancy in NiCo 2 S 4. [ABSTRACT FROM AUTHOR]

• Problems in high current density operation of PEMFCs are comprehensively reviewed. • Progress of optimisations addressing the problems is summarised. • Perspectives to improve the high current density performance are discussed. The proton exchange membrane fuel cell (PEMFC) is a highly promising and advanced technology in energy development due to its exceptional efficiency and eco-friendly characteristics. Addressing the excessive cost and size limitations, particularly by enhancing power density through increased current density, has been a focal point. However, high current density (HCD) operation results in intricate limitations in mass transfer, catalyst activity, degradation, as well as water, thermal, and gas management in single cells and stacks. This comprehensive review delves into the problems encountered by PEMFCs operating at HCDs for both single cells and stack configurations. A detailed research progress from multiple perspectives, including structural, material, and manufacturing considerations across various components is offered. Additionally, insights into the intricacies of thermal, water, and gas management at both the single-cell and stack levels are provided. Finally, the review offers perspectives on future developments based on the identified problems and ongoing research progress. [ABSTRACT FROM AUTHOR]

Carbon corrosion in catalysts is one of the main limitations of proton exchange membrane fuel cell (PEMFC) lifetime. Water flooding can accelerate the carbon corrosion rate in PEMFCs, especially at high current densities. Increasing the operation temperature can effectively mitigate water flooding and improve the water management performance of PEMFCs. However, elevated temperatures also increase the carbon corrosion reaction kinetics, accelerating the degradation of PEMFCs lifetime. To study the effects of temperature on carbon corrosion at high current densities, PEMFCs operating for 100 h at 65 °C and 90 °C under 1600 mA·cm−2 were investigated. The results showed that the electrochemical active surface area (ECSA) of the cathode catalyst layer decreased by 9.16% and 13.92% at 65 °C and 90 °C, respectively. The reduction rate of the catalyst layer in the nonflooding area increased as the operating temperature increased. However, the reduction rate decreased by 69.82% and 54.04% at 65 °C and 90 °C, respectively, at the outlet of the PEMFC. Therefore, water flooding is the key issue causing lifetime degradation, and water management is essential for PEMFCs that operate at high current densities, especially at the outlet of PEMFCs.

Induced disorder in graphene enables changes in electrical and thermal transport. It has been shown previously that disorder is very important for electron cooling in graphene through disorder-assisted electron-phonon scattering, particularly via the supercollisions process. Here we study electron-momentum relaxation due to electron-phonon scattering while increasing the degree of disorder. With in-situ scanning thermal microscopy we monitor the temperature rise in the constriction region of a bowtie-shaped graphene device while increasing the disorder by means of feedback-controlled voltage ramps at high-current densities. Analysis of the combined thermal and electrical measurements in the low bias regime shows that the relative change of the momentum scattering rate vs temperature, as measured at room temperature, increases with strong local disorder. By excluding other candidate mechanisms for this phenomenon, including a change of the charge carriers density and activation of optical phonons, we conclude that the increase we observe in the temperature-dependent component of the scattering rate is likely due to new acoustic phonon scattering channels that open up as disorder increases. [Display omitted] [ABSTRACT FROM AUTHOR]

We have shown that it is possible to create effective light-emitting devices with interband recombination based on current injection unipolar heterostructures. In the proposed concept, effective interband radiative recombination at current pumping is achieved by (1) the use of a quantum well (QW) located in the narrow bandgap carrier accumulation region of the unipolar heterostructure and (2) the presence of an electric field domain layer that is formed in the separate wide bandgap region of the unipolar heterostructure. Because of the impact ionization, this domain acts as a source of nonequilibrium electrons and holes. InGaAs active region and AlGaAs impact ionization region design optimization, which was carried out using the energy balance model, allowed us to increase current conversion efficiency up to 23% (for pump currents in the range between 52 and 60 A) and the QW electron hole density is sufficient for the effective radiative recombination and high optical gain. [ABSTRACT FROM AUTHOR]

Water electrolysis is promising for industrial hydrogen production to achieve a sustainable and green hydrogen economy, but the high cost of the technology limits its market share. Developing efficient yet economic electrocatalysts is crucial to decrease the cost of electricity and electrolytic cell. Meanwhile, electrolysis in seawater electrolyte can further reduce feedstock cost. Here, a type of electrocatalyst is synthesized, where trace precious metals are strongly anchored on a corrosion‐resistive matrix. As an example, the produced Pt/Ni‐Mo electrocatalyst only needs an overpotential of 113 mV to reach an ultrahigh current density of 2000 mA cm−2 in the saline‐alkaline electrolyte, demonstrating the best performance reported thus far. It shows high activity and long durability in various electrolytes and under harsh conditions, including strong alkaline and simulated seawater electrolytes, and under elevated temperatures up to 80 °C. This electrocatalyst is produced on a large scale at a low cost and shows good performance in a commercial membrane electrode assembly stack, demonstrating its feasibility for practical water electrolysis. [ABSTRACT FROM AUTHOR]

Water electrolysis is promising for industrial hydrogen production to achieve a sustainable and green hydrogen economy, but the high cost of the technology limits its market share. Developing efficient yet economic electrocatalysts is crucial to decrease the cost of electricity and electrolytic cell. Meanwhile, electrolysis in seawater electrolyte can further reduce feedstock cost. Here, a type of electrocatalyst is synthesized, where trace precious metals are strongly anchored on a corrosion‐resistive matrix. As an example, the produced Pt/Ni‐Mo electrocatalyst only needs an overpotential of 113 mV to reach an ultrahigh current density of 2000 mA cm−2 in the saline‐alkaline electrolyte, demonstrating the best performance reported thus far. It shows high activity and long durability in various electrolytes and under harsh conditions, including strong alkaline and simulated seawater electrolytes, and under elevated temperatures up to 80 °C. This electrocatalyst is produced on a large scale at a low cost and shows good performance in a commercial membrane electrode assembly stack, demonstrating its feasibility for practical water electrolysis. [ABSTRACT FROM AUTHOR]

Although some strategies have been triggered to address the intrinsic drawbacks of zinc (Zn) anodes in aqueous Zn‐ion batteries (ZIBs), the larger issue of Zn anodes unable to cycle at a high current density with large areal capacity is neglected. Herein, the zinc phosphorus solid solution alloy (ZnP) coated on Zn foil (Zn@ZnP) prepared via a high‐efficiency electrodeposition method as a novel strategy is proposed. The phosphorus (P) atoms in the coating layer are beneficial to fast ion transfer and reducing the electrochemical activation energy during Zn stripping/plating processes. Besides, a lower energy barrier of Zn2+ transferring into the coating can be attained due to the additional P. The results show that the as‐prepared Zn@ZnP anode in the symmetric cell can be cycled at a current density of 15 mA cm−2 with an areal capacity of 48 mAh cm−2 (depth of discharge, DOD ≈ 82%) and even at an ultrahigh current density of 20 mA cm−2 and DOD ≈ 51%. Importantly, a discharge capacity of 154.4 mAh g−1 in the Zn/MnO2 full cell can be attained after 1000 cycles at 1 A g−1. The remarkable effect achieved by the developed strategy confirms its prospect in the large‐scale application of ZIBs for high‐power devices. [ABSTRACT FROM AUTHOR]

Omega-shaped non-planar gate architecture is adopted to enhance the gate coupling of the MoS 2 transistor. The devices present a high current of 0.89 A/μm and transconductance of 32.7 μS/μm. This work provides an alternative strategy to realize high-performance field-effect transistors based on two-dimensional materials. [Display omitted] The ever-decreasing size of transistors requires effectively electrostatic control over ultra-thin semiconductor body. Rational design of the gate configuration can fully persevere the intrinsic property of two-dimensional (2D) semiconductors. Here we design and demonstrate a 2D MoS 2 transistor with omega-shaped gate, in which the local gate coupling is enhanced by the non-planar geometry. The omega-shaped non-planar transistors exhibit a high current of 0.89 A/μm and transconductance of 32.7 μS/μm. The high performance and desirable current saturation promise the construction of robust logic gate. The inverters show a voltage gain of 26.6 and an ideal total margin nearly 89%. We also assemble NOT-AND (NAND) gate on an individual MoS 2 flake, and the constructed NAND gate demonstrates the universal functionality of the transistors as well. This work provides an alternative strategy to fully take the advantages of 2D materials for high-performance field-effect transistors. [ABSTRACT FROM AUTHOR]

Highlights: N-doped graphene-coated structure and mesoporous nano-sheet can efficiently boost active sites and stability for hydrogen and oxygen evolution reaction. NiCo@C-NiCoMoO/NF exhibits low overpotentials for HER (266 mV) and OER (390 mV) at ± 1000 mA cm−2. For water electrolysis, it can hold at 1000 mA cm−2 for 43 h in 6.0 M KOH + 60 °C condition.Developing highly effective and stable non-noble metal-based bifunctional catalyst working at high current density is an urgent issue for water electrolysis (WE). Herein, we prepare the N-doped graphene-decorated NiCo alloy coupled with mesoporous NiCoMoO nano-sheet grown on 3D nickel foam (NiCo@C-NiCoMoO/NF) for water splitting. NiCo@C-NiCoMoO/NF exhibits outstanding activity with low overpotentials for hydrogen and oxygen evolution reaction (HER: 39/266 mV; OER: 260/390 mV) at ± 10 and ± 1000 mA cm−2. More importantly, in 6.0 M KOH solution at 60 °C for WE, it only requires 1.90 V to reach 1000 mA cm−2 and shows excellent stability for 43 h, exhibiting the potential for actual application. The good performance can be assigned to N-doped graphene-decorated NiCo alloy and mesoporous NiCoMoO nano-sheet, which not only increase the intrinsic activity and expose abundant catalytic activity sites, but also enhance its chemical and mechanical stability. This work thus could provide a promising material for industrial hydrogen production. [ABSTRACT FROM AUTHOR]

Cu plating bath for high-speed electrodeposition of Cu pillar was designed in consideration of a flat top morphology of pillar and a pillar height uniformity. An ideal polarization curve was assumed for the flat top morphology. To obtain the ideal polarization curve, an effect of organic additive concentration and solution agitation on the polarization curve were investigated. The basic bath components were optimized considering a Wagner number to improve the pillar height uniformity. To confirm the pillar top morphology and the pillar height uniformity, a 300-mm diameter wafer was plated with Cu at 20 A/dm² . As a result, improved pillar top morphology and pillar height uniformity were obtained. The optimized plating bath was applied to the plating of a large-size panel of 415 3 510 mm. [ABSTRACT FROM AUTHOR]

Presented here is an electrochemical three-electrode Gas Diffusion Electrode (GDE) cell tailored for operandoand in situ investigations of electrocatalytic processes, with a particular focus on X-ray scattering studies. The optimized cell is engineered to accommodate the minimal sample-detector distances requisite for comprehensive X-ray total scattering investigations. An in-depth understanding of catalytic processes requires their study under 'working' conditions. Configured as a flow-cell, the setup therefore enables the examination of electrocatalysts under high current densities and associated gas evolution phenomena, particularly pertinent for reactions like the oxygen evolution reaction (OER). Notably, its transparency simplifies cell alignment, troubleshooting, and facilitates scans through the catalyst layer, crucial for background corrections. Demonstrating its versatility, we showcase its utility through Small Angle X-ray Scattering (SAXS), X-ray Diffraction (XRD), and X-ray Pair Distribution Function (PDF) analyses of total scattering data., (Copyright 2024 Gustav K. H. Wiberg, Rebecca K. Pittkowski, Stefanie Punke , Olivia Aalling-Frederiksen , Kirsten M. Ø. Jensen, Matthias Arenz. License: This work is licensed under a Creative Commons Attribution 4.0 International License.)

Developing robust electrodes with high catalytic performance is a key step for expanding practical HER (hydrogen evolution reaction) applications. This paper reports on novel porous Mo 2 C-based ceramics with oriented finger-like holes directly used as self-supported HER electrodes. Due to the suitable MoO 3 sintering additive, high-strength (55 ± 6 MPa) ceramic substrates and a highly active catalytic layer are produced in one step. The in situ reaction between MoO 3 and Mo 2 C enabled the introduction of O in the Mo 2 C crystal lattice and the formation of Mo 2 C(O)/MoO 2 heterostructures. The optimal Mo 2 C-based electrode displayed an overpotential of 333 and 212 mV at 70 °C under a high current intensity of 1500 mA cm -2 in 0.5 m H 2 SO 4 and 1.0 m KOH, respectively, which are markedly better than the performance of Pt wire electrode; furthermore, its price is three orders of magnitude lower than Pt. The chronopotentiometric curves recorded in the 50 - 1500 mA cm -2 range, confirmed its excellent long-term stability in acidic and alkaline media for more than 260 h. Density functional theory (DFT) calculations showed that the Mo 2 C(O)/MoO 2 heterostructures has an optimum electronic structure with appropriate *H adsorption-free energy in an acidic medium and minimum water dissociation energy barrier in an alkaline medium., (© 2023 Wiley‐VCH GmbH.)

Electrocatalysts with low Pt loading mass to achieve high current density (≥1 A cm -2 ) for hydrogen evolution reaction (HER) are still extremely challenging due to the limited intrinsic activity and weak stability of catalytic sites. The modulation of the electronic microenvironment of the support-Pt structure is crucial to enhance the intrinsic activity and stability of catalytic sites. Herein, an innovative titanium oxycarbide (Ti V CO) solid solution with Ti vacancies (Ti V ) is proposed as support to anchor sub-nanoscale Pt atomic clusters (Pt ACs) and a stable "Ti V -Pt ACs" structure is carefully designed. The electronic microenvironment of "Ti V -Pt ACs" is indirectly optimized by an unsaturated C/O site near Ti V . Thanks to this, novel "Ti V -Pt ACs" structure (Pt@Ti V CO) with low Pt loading mass (2.44 wt.%) exhibits excellent HER activity in acidic solution and the mass activity is more than ten times that of commercial 20% Pt/C at the overpotentials of 50 and 100 mV. Particularly, Pt@Ti V CO shows amazing stability at high and fluctuating current density of 1-2 A cm -2 for 120 h. This work provides a novel and promising method to develop stable and low-loading Pt-based catalysts adapting to high current density., (© 2023 Wiley‐VCH GmbH.)

Graphene is atomically thin, possesses excellent thermal conductivity, and is able to withstand high current densities, making it attractive for many nanoscale applications such as field-effect transistors, interconnects, and thermal management layers. Enabling integration of graphene into such devices requires nanostructuring, which can have a drastic impact on the self-heating properties, in particular at high current densities. Here, we use a combination of scanning thermal microscopy, finite element thermal analysis, and operando scanning transmission electron microscopy techniques to observe prototype graphene devices in operation and gain a deeper understanding of the role of geometry and interfaces during high current density operation. We find that Peltier effects significantly influence the operational limit due to local electrical and thermal interfacial effects, causing asymmetric temperature distribution in the device. Thus, our results indicate that a proper understanding and design of graphene devices must include consideration of the surrounding materials, interfaces, and geometry. Leveraging these aspects provides opportunities for engineered extreme operation devices.

The development of facile methods for constructing highly active, cost-effective catalysts that meet ampere-level current density and durability requirements for an oxygen evolution reaction is crucial. Herein, a general topochemical transformation strategy is posited: M-Co 9 S 8 single-atom catalysts (SACs) are directly converted into M-CoOOH-TT (M = W, Mo, Mn, V) pair-sites catalysts under the role of incorporating of atomically dispersed high-valence metals modulators through potential cycling. Furthermore, in situ X-ray absorption fine structure spectroscopy is used to track the dynamic topochemical transformation process at the atomic level. The W-Co 9 S 8 breaks through the low overpotential of 160 mV at 10 mA cm -2 . A series of pair-site catalysts exhibit a large current density of approaching 1760 mA cm -2 at 1.68 V vs reversible hydrogen electrode (RHE) in alkaline water oxidation and achieve a ≈240-fold enhancement in the normalized intrinsic activity compare to that reported CoOOH, and sustainable stability of 1000 h. Moreover, the O─O bond formation is confirmed via a two-site mechanism, supported by in situ synchrotron radiation infrared and density functional theory (DFT) simulations, which breaks the limit of adsorption-energy scaling relationship on conventional single-site., (© 2024 Wiley‐VCH GmbH.)

The high-current-density Zn-air battery shows big prospects in next-generation energy technologies, while sluggish O 2 reaction and diffusion kinetics barricade the applications. Herein, the sequential assembly is innovatively demonstrated for hierarchically mesoporous molybdenum carbides/carbon microspheres with a tunable thickness of mesoporous carbon layers (Meso-Mo 2 C/C-x, where x represents the thickness). The optimum Meso-Mo 2 C/C-14 composites (≈2 µm in diameter) are composed of mesoporous nanosheets (≈38 nm in thickness), which possess bilateral mesoporous carbon layers (≈14 nm in thickness), inner Mo 2 C/C layers (≈8 nm in thickness) with orthorhombic Mo 2 C nanoparticles (≈2 nm in diameter), a high surface area of ≈426 m 2  g -1 , and open mesopores (≈6.9 nm in size). Experiments and calculations corroborate the hierarchically mesoporous Mo 2 C/C can enhance hydrophilicity for supplying sufficient O 2 , accelerate oxygen reduction kinetics by highly-active Mo 2 C and N-doped carbon sites, and facilitate O 2 diffusion kinetics over hierarchically mesopores. Therefore, Meso-Mo 2 C/C-14 outputs a high half-wave potential (0.88 V vs RHE) with a low Tafel slope (51 mV dec -1 ) for oxygen reduction. More significantly, the Zn-air battery delivers an ultrahigh power density (272 mW cm -2 ), and an unprecedented 100 h stability at a high-current-density condition (100 mA cm -2 ), which is one of the best performances., (© 2023 Wiley‐VCH GmbH.)

In this paper, we report on a novel E-mode AlGaN/GaN gates-seperating groove heterostructure field-effect transistor (GSG HFET). The current turn-on/off is controlled by changing gate voltage to regulate the horizontal energy band between the double gates. A threshold voltage of 0.23 V and a high drain current density of 851 mA/mm are obtained in GSG HFET. Compared with the proposed depletion-mode device, the maximum drain current of the GSG HFET deceases slightly (about 7%). It is noteworthy that the threshold voltage is less sensitive to the etching time. The devices show high-uniformity threshold voltage of 0.23 V within wide etching time range from 5 to 9 min.

Here, it is reported a vertical electrolyte transistor (VET) whose structure is based on stacked layers: bottom contact → channel → permeable intermediate electrode → ion gel (electrolyte gate dielectric) → gate top contact. This VET depicts versatility to work with two different mode of operation, as: Electrolyte-Gated Vertical Organic Field Effect Transistor (Electrolyte-Gated VOFET) or Vertical Organic Electrochemical Transistor (VOECT). The difference is regarding to the transistor transconductance that occurs due to induced charge carriers or ionic current, respectively. Here, the focus is on giving special attention to the electrical characterization of the VET diode cell in comparison to the VET full architecture. These measurements are able to provide the baseline output current from a VET and consequently distinguish it from possibles different modes of operation created by ionic species. Both modes of operation show that this VET is able to work at very low voltage range and drive a high current density. Image 1 • Vertical Electrolyte Transistors (VETs) and their different modes of operation obtained from just one structure. • Transconductance as a consequence of induced charge carriers and/or ionic current. • Electrolyte-Gated VOFET → transconductance created by field effect only. • VOECT → transconductance created by ionic and electric current. • VETs → transistor class able to operate with very low bias and high current density. [ABSTRACT FROM AUTHOR]

Large scale synthesis of high-efficiency bifunctional electrocatalyst based on cost-effective and earth-abundant transition metal for overall water splitting in the alkaline environment is indispensable for renewable energy conversion. In this regard, meticulous design of active sites and probing their catalytic mechanism on both cathode and anode with different reaction environment at molecular-scale are vitally necessary. Herein, a coordination environment inheriting strategy is presented for designing low-coordination Ni2+ octahedra (L-Ni-8) atomic interface at a high concentration (4.6 at.%). Advanced spectroscopic techniques and theoretical calculations reveal that the self-matching electron delocalization and localization state at L-Ni-8 atomic interface enable an ideal reaction environment at both cathode and anode. To improve the efficiency of using the self-modification reaction environment at L-Ni-8, all of the structural features, including high atom economy, mass transfer, and electron transfer, are integrated together from atomic-scale to macro-scale. At high current density of 500 mA/cm2, the samples synthesized at gram-scale can deliver low hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) overpotentials of 262 and 348 mV, respectively. [ABSTRACT FROM AUTHOR]

Summary: Ultrathin FeNiOxHy nanoflake arrays with the thickness of only ~4.5 nm were prepared on Ni foam (NF) via a facile hydrothermal reaction. The oxygen evolution reaction (OER) properties of the obtained sample (FeNiOxHy/NF) were investigated under alkaline conditions (1.0 M KOH). The optimized FeNiOxHy/NF displays extremely small overpotentials of only 195 and 306 mV to achieve the current densities of 10 and 1000 mA cm−2, respectively, and shows almost no potential attenuation during the 160 hours of stability test even the current density is up to 1000 mA cm−2, demonstrating brilliant OER catalytic activity and durability. FeOOH and the NiOOH produced from the in situ oxidation of the surface Ni atoms of the NF substrate are the active sites. The synergistic effect between FeOOH and NiOOH is responsible for the high performances. To our knowledge, the high activity and stability of FeNiOxHy/NF catalyst outperform almost all of the OER catalysts reported to date. These informative findings are valuable not only for understanding the mechanism of OER but also for the design of cheap transition metal catalysts for industrial water electrolysis at high current densities. [ABSTRACT FROM AUTHOR]

The lithium metal anode is one of the most promising anodes for next‐generation high‐energy‐density batteries. However, the severe growth of Li dendrites and large volume expansion leads to rapid capacity decay and shortened lifetime, especially in high current density and high capacity. Herein, a soft 3D Au nanoparticles@graphene hybrid aerogel (AuGA) as a lithiophilic host for lithium metal anode is proposed. The large surface area and interconnected conductive pathways of the AuGA significantly decrease the local current density of the electrode, enabling uniform Li deposition. Furthermore, the 3D porous structure effectively accommodates the large volume expansion during Li plating/stripping, and the LixAu alloy serves as a solid solution buffer layer to completely eliminate the Li nucleation over‐potential. Symmetric cells can stably cycle at 8 mA cm−2 for 8 mAh cm−2 and exhibit ultra‐long cycling: 1800 h at 2 mA cm−2 for 2 mAh cm−2, and 1200 h at 4 mA cm−2 for 4 mAh cm−2, with low over‐potential. Full cells assemble with a Cu@AuGALi anode and LiFePO4 cathode, can sustain a high rate of 8 C, and retain a high capacity of 59.6 mAh g−1 after 1100 cycles at 2 C. [ABSTRACT FROM AUTHOR]

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NASCION‐type Li conductors have great potential to bring high capacity solid‐state batteries to realization, related to its properties such as high ionic conductivity, stability under ambient conditions, wide electrochemical stability window, and inexpensive production. However, their chemical and thermal instability toward metallic lithium (Li) has severely hindered attempts to utilize Li as anode material in NASCION‐based battery systems. In this work, it is shown how a tailored multifunctional interlayer between the solid electrolyte and Li anode can successfully address the interfacial issues. This interlayer is designed by creating a quasi‐solid‐state paste in which the functionalities of LAGP (Li1.5Al0.5Ge1.5(PO4)3) nanoparticles and an ionic liquid (IL) electrolyte are combined. In a solid‐sate cell, the LAGP‐IL interlayer separates the Li metal from bulk LAGP and creates a chemically stable interface with low resistance (≈5 Ω cm2) and efficiently prevents thermal runaway at elevated temperatures (300 °C). Solid‐state cells designed with the interlayer can be operated at high current densities, 1 mA cm−2, and enable high rate capability with high safety. Here developed strategy provides a generic path to design interlayers for solid‐state Li metal batteries. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries, due to the high theoretical energy density, are regarded as one of the most promising candidates for breaking the limitations of energy‐storage system based on Li‐ion batteries. Tremendous efforts have been made to meet the challenge of high‐performance Li–S batteries, in which a sulfur loading of above 5 mg cm−2 delivers an areal capacity higher than 5 mAh cm−2 without compromising specific capacity and cycling stability for practical applications. However, serious problems have been exposed during the scaling up of the sulfur loading. In this review, based on mechanistic insights into structural configuration, catalytic conversion, and interfacial engineering, the problems and corresponding strategies in the development of high‐loading Li–S batteries are highlighted and discussed, aiming at bridging the gap between fundamental research and practical cell‐level designs. Stemming from the current achievements, future directions targeting the high‐energy‐density Li–S batteries for commercialization are proposed. [ABSTRACT FROM AUTHOR]

Exploring a sustainable, cost-effective, and efficient bifunctional electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is very significant as well as challenging to develop an energy conversion–storage system. Herein, we demonstrate a fabrication technique of an organic–inorganic hybrid polypyrrole (ppy)/AgVO3, and its surface was further modified by porphrin (porphy) to boost its catalytic performances. The C,N-based ppy/AgVO3/porphy nanocatalyst acts as a charge transport highway to accelerate the sluggish OER/ORR kinetics and results in its impressive bifunctional performances. It exhibits an outstanding four-electron ORR activity with higher onset potential (1.03 V) and remarkable OER catalytic performance carrying a lowest overpotential (η10) of 220 mV, largely outperformingAgVO3 and ppy/AgVO3. Initially the very low ORR/OER activities of AgVO3 nanorods come from poor O2 and OH– adsorption on V5+ sites due to its extremely low electrochemical active surface area (ECSA) and poor electrical conductivity. The ppy loading has improved its catalytic performances by providing new active sites due to the presence of pyrrolic-N. Finally, the active site density was greatly enhanced after porphy loading over ppy/AgVO3, as porphy offers additional pyridinic-N along with pyrrolic-N atom. Furthermore, developed mesoporous surface after porpy incorporation provides high electrical conductivity, large surface area, enhanced charge–mass transport, close electrolyte–catalyst contact, and improved stability. Considering its bifunctional activity, NComp has been further evaluated by integrating it into a prototype zinc–air battery (ZAB), where a low discharge–charge voltage gap (0.71 V at 10 mA·cm–2) and a large peak power density (301 mW·cm–2) were achieved. Moreover, the NComp-based rechargeable ZAB (RZAB) is efficient enough to be operated evenly for 100 discharge–charge cycles. Most importantly, our findings may offer a powerful yet easy fabrication method of corrosion resistant high-performance catalyst through regulating active sites for investigating catalysis. [ABSTRACT FROM AUTHOR]

Organic light‐emitting diodes (OLEDs) can emit light over much larger areas than their inorganic counterparts, offer mechanical flexibility, and can be readily integrated on various substrates and backplanes. However, the amount of light they emit per unit area is typically lower and the required operating voltage is higher, which can be a limitation for emerging applications of OLEDs, e.g., in outdoor and high‐dynamic‐range displays, biomedical devices, or visible‐light communication. Here, high‐luminance, blue‐emitting (λpeak = 464 nm), fluorescent p–i–n OLEDs are developed by combining three strategies: First, the thickness of the intrinsic layers in the device is decreased to reduce internal voltage loss. Second, different electron‐blocking layer materials are tested to recover efficiency losses resulting from this thickness reduction. Third, the geometry of the anode contact is optimized, which leads to a substantial reduction in the in‐plane resistive voltage losses. The OLEDs retain a maximum external quantum efficiency of 4.4% as expected for an optimized fluorescent device and reach a luminance of 132 000 cd m−2 and an optical power density of 2.4 mW mm−2 at 5 V, a nearly eightfold improvement compared to the original reference device. [ABSTRACT FROM AUTHOR]

The high-nickel ternary cathode material LiNixCoyMn1-x-yO2 has high theoretical capacity and can be filled the power density requirement of a foot-powered car. It is placed on high expectations. However, Li/Ni mixing occurred during charging and discharging, resulting in poor cycle performance of the material. In this paper, spherical Ni0.66Co0.20Mn0.14(OH)2 precursor as prepared by co-precipitation. Then, well-ordered spherical [Li(1-x)Kx](Ni0.66Co0.20Mn0.14)O2 was synthesized. The effect of k substitution on the crystal structure and electrochemical properties of Li(Ni0.66Co0.20Mn0.14)O2 systematically by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), charge-discharge test, cyclic voltammetry (C–V) method, and electrochemical impedance spectroscopy (EIS) test. The initial discharge specific capacity of Li0.98K0.02Ni0.66Co0.20Mn0.14O2 is 202.0 mAh/g, 169.3 mAh/g, 138.8 mAh/g, and 117.8 mAh/g at 0.1 C, 0.2 C, 0.5 C, 1 C, respectively, which is higher than other materials. The [Li0.98K0.02](Ni0.66Co0.20Mn0.14)O2 shows the initial discharge capacity of 117.8 mAh/g with the capacity retention of 86.1% after 30 cycles at 1 C. It shows good cycle performance and rate performance. Results showed K substitution played an important role in the superior reversible capacity and good cycling performance of Li(Ni0.66Co0.20Mn0.14)O2. [ABSTRACT FROM AUTHOR]

In this study, the influence of the anodic porous transport layer (PTL) on the performance of a proton exchange membrane (PEM) electrolysis laboratory test cell was investigated up to a current density of 5 A*cm−2. Operation parameters such as water volume flow rate (0.2–0.8 l*min−1), temperature (40–80 °C) and pressure (1–30 barg) have been varied to study their influence on the polarisation curve. Special attention has been paid to the appearance of mass transport losses (MTL) and their dependency on the operation parameters. Two stack designs that are commercially in use - one with and one without flow channels underneath the PTL - were tested and evaluated. Fundamental differences in performance have been observed between the two cell designs. Operation parameters only show impact on performance for the configuration without flow channels. Here, MTL were observed in several cases already for current densities around and above 1.0 A*cm−2. An increase in pressure, temperature or water flow rate reduces MTL for these configurations. • Performances of electrolysers with and without flow field can differ significantly. • Also temperature (T), pressure (p) and flow rate (Q) influence the performance. • Performance of electrolysers without flow field benefit from increased T, p and Q. • Porosities and particle/fiber diameters are not enough to characterise PTLs. • Also in-plane and through-plane permeability are needed for proper characterisation. [ABSTRACT FROM AUTHOR]