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[Display omitted] Enhancing double-phase mass transfer capability and reducing overpotential at high currents are critical in the oxygen evolution reaction (OER) catalyst design. In this work, nickel–iron layered double hydroxide (NiFe-LDH) loaded on nickel foam (NF) was used as a self-sacrificing template for subsequent growth of nickel–iron Prussian blue (NiFe-PBA) hollow nanocubes on its sheet arrays. The triple-scale porous structure is therefore in -situ constructed in the produced NiFe-PBA@LDH/NF catalyst, where NiFe-PBA nanocubes, NiFe-LDH sheets and NF skeletons provide pores at hundred-nanometers, microns and hundred-microns, respectively. Due to the successful construction of hierarchical mass transfer channels in the catalyst, the overpotential required to deliver 1000 mA cm−2 OER is only 396 mV, which is 80 mV lower than that of NiFe-LDH/NF with a double-scale porous structure, manifesting the importance of the appropriate mass transfer channels, promoting the potential application of the NiFe-PBA@LDH/NF catalyst in industrial-scale electrolysers. [ABSTRACT FROM AUTHOR]

Ni/Mo 2 C hetero-sheet arrays are grown vertically on nickel foam skeleton to utilize the advantages of Ni and Mo 2 C on promotion of HER kinetics and 3D structure on mass transfer and accessibility and only 151 and 271 mV overpotentials are needed to deliver 100 and 1000 mA/cm2 HER, respectively. [Display omitted] • Ni-doped Mo 2 C nanosheet arrays are grown vertically on nickel foam skeleton. • Polyvinylpyrrolidone is used as soft template for catalyst preparation. • 151 and 271 mV overpotentials are needed to deliver 100 and 1000 mA/cm2 HER. • The HER can stably operate for more than 500 h. Practical structural design and electronic regulation are significant for synthesising efficient electrocatalysts. Therefore, a facile soft-template approach has been applied to successfully grow Ni/Mo 2 C heterojunction nanosheet arrays on nickel foam (NF) skeleton (NS-Ni/Mo 2 C@NF) using polyvinylpyrrolidone (PVP) as a soft template. The density functional theory (DFT) calculations reveal that abundant Ni/Mo 2 C heterojunction in NS-Ni/Mo 2 C@NF can provide many active sites with a moderate hydrogen adsorption free energy (ΔG H* , 0.037 eV). Benefiting from this nanosheet array structure and abundant Ni/Mo 2 C heterojunctions, the NS-Ni/Mo 2 C@NF catalyst can efficiently catalyze HER, especially at large current densities. As a result, only 151 and 271 mV overpotentials are needed to deliver 100 and 1000 mA/cm2 HER, respectively. More importantly, the hydrogen production testing with NS-Ni/Mo 2 C@NF as the working electrode can run stably for 500 h without activity decay under the current density of 500 mA/cm2 commonly used in industrial water electrolyzers, indicating that NS-Ni/Mo 2 C@NF has broad application prospects. [ABSTRACT FROM AUTHOR]

• The ternary Ni-N-P microparticles is in-situ grown through one-step phosphorization. • The ternary Ni-N-P microparticles possess high activity for catalyzing both HER and OER. • Ni-N-P microparticles based electrolyzer enables effective water splitting with high stability. The development of high-activity and low-cost electrocatalysts through simple one-step method is of vital importance for electrocatalytic water splitting, but still remains a challenge. In this work, ternary Ni-N-P microparticles, an analogue of NiC x , are in-situ grown on nickel foam through one-step phosphorization at low temperature under atmosphere of ammonia. The unique microparticles-like morphology and suitable electronic structure render them enhanced electron and mass transfer ability, ensuring superior activity and good durability in catalyzing oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) under alkaline condition. Specifically, the optimal Ni-N-P microparticles can deliver 10 mA/cm2 at the overpotential of 260 mV and 180 mV vs. reversible hydrogen electrode (RHE) for OER and HER, respectively. Additionally, only a cell voltage of 1.7 V is required to afford 10 mA/cm2 when the prepared Ni-N-P microparticles serve as both anode and cathode in two-electrode configuration for overall water splitting. The Ni-N-P microparticles hold promise as cost-effective and efficient candidate for practical water splitting devices. [ABSTRACT FROM AUTHOR]