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[Display omitted] Construction of heterogeneous interfaces with dual active components to synergistically promote both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an effective strategy for facilitating electrochemical water splitting, but the appropriate active component regulation via simple synthesis procedures is still challenging. Herein, the Co and Co 2 Mo 3 O 8 active components are screened to construct effective heterogeneous interfaces and successfully integrated on Ni foam by thermal reduction of cobalt molybdate precursor. And this bifunctional electrode (Co/Co 2 Mo 3 O 8 /NF) required overpotentials of only 164 and 360 mV to drive the 100 mA cm−2 for HER and OER in alkaline media, respectively. Theoretical calculations showed that the electron transfer occurred from Co to Co 2 Mo 3 O 8 at the interface, then the formed interfacial cobalt atoms with deficient electron were beneficial for water activation, and reduced energy barrier of water dissociation under the synergistic effect of Co 2 Mo 3 O 8. Notably, the alkaline electrolyzer based on symmetric Co/Co 2 Mo 3 O 8 /NF electrodes generated 100 mA cm−2 at a voltage of only 1.75 V, surpassing commercially available precious-metal Pt/RuO 2 -based catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Hydrogen energy is expected to replace fossil fuels as a mainstream energy source in the future. Currently, hydrogen production via water electrolysis yields high hydrogen purity with easy operation and without producing polluting side products. Presently, platinum group metals and their oxides are the most effective catalysts for water splitting; however, their low abundance and high cost hinder large-scale hydrogen production, especially in alkaline and neutral media. Therefore, the development of high-efficiency, durable, and low-cost electrocatalysts is crucial to improving the overpotential and lowering the electrical energy consumption. As a solution, Ni 2 P has attracted particular attention, owing to its desirable electrical conductivity, high corrosion resistance, and remarkable catalytic activity for overall water splitting, and thus, is a promising substitute for platinum-group catalysts. However, the catalytic performance and durability of raw Ni 2 P are still inferior to those of noble metal-based catalysts. Heteroatom doping is a universal strategy for enhancing the performance of Ni 2 P for water electrolysis over a wide pH range, because the electronic structure and crystal structure of the catalyst can be modulated, and the adsorption energy of the reaction intermediates can be adjusted via doping, thus optimizing the reaction performance. In this review, first, the reaction mechanisms of water electrolysis, including the cathodic hydrogen evolution reaction and anodic oxygen evolution reaction, are briefly introduced. Then, progress into heteroatom-doped nickel phosphide research in recent years is assessed, and a discussion of each representative work is given. Finally, the opportunities and challenges for developing advanced Ni 2 P based electrocatalysts are proposed and discussed. [ABSTRACT FROM AUTHOR]

[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]

Graphical abstract Highlights • We successfully synthesized sea urchin-like ternary cobalt phosphosulfide (CoPS). • CoPS is a high-efficiency bifunctional electrocatalyst for overall water splitting. • DFT calculations reveal the mechanism that CoPS has favorable performance for OER and HER. Abstract The development of efficient non-noble bifunctional electrocatalysts for the overall water splitting is a pressing and challenging task. In this work, we report a sea urchin-like cobalt phosphosulfide (CoPS) ternary compound for overall water splitting. Because CoPS contains more than one nonmetallic element, ternary compounds possess dianions might lead to modulated electronic structure and thus modified their electrocatalytic properties. Our DFT calculation results reveal that the ternary CoPS exhibits favorable performance for both the oxygen evolution reaction and hydrogen evolution reaction. Experimentally set as cathode and anode in a full cell for overall water splitting, the CoPS cell needs a voltage of only ∼1.59 V to reach a current density of 10 mA cm−2 and has outstanding stability. Our results open up a path to search for alternative bifunctional electrocatalyst materials to substitute for noble metals in overall water splitting. [ABSTRACT FROM AUTHOR]