developing non-precious electrocatalysts with high performance is of primary significance in a fascinating and scalable water splitting technology for hydrogen production. A number of nickel (Ni)-based heterogeneous catalysts have been designed and synthesized to lower the overpotentials for large current densities due to low cost and facile synthesis. Herein, recent progress on Ni-based composites functioning on hydro-gen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting is summarized. The synthesis strategies, structure design and performance analysis of Nibased heterostructured catalysts are thoroughly discussed, aiming to promote the development of highly efficient electrocatalysts that may ultimately replace the noble-metal based catalysts and bring water splitting into the practical application.Yuting Li, a Ph.D. student in the Department of Chemical Engineering at Nanjing University of Science and Technology. Her research interests focus on the rational design and synthesis optimization of bifunctional composites and structure control of non-noble-metal heterogeneous nanomaterials for electrocatalyzing water splitting.

The development of highly practical and stable catalysts for hydrogen evolution reaction (HER) remains challenging to accomplish continuous H2 production through water electrolysis. In this work, the porous network Co−B−P amorphous‐crystalline catalyst was synthesized through a hydrothermal‐alternating immersion boronization‐phosphidation pathway. The Co−B−P nanocomposite consists of the amorphous Co−B−O and crystalline Co2P2O7 compositions. The Co−B−P catalyst shows highly effective HER electrochemical performance with low overpotential of 51 mV at current density of 10 mA cm−2 and Tafel slope of 44 mV dec−1 in alkaline solution (pH=14). After 1000 cycles of CV scanning, the catalyst shows no significant reduction in HER performance. Such superior HER performance can be ascribed to (1) the amorphous Co−B−O structure accelerating charge transfer between active sites and intermediates and (2) the formed P−O bonds of crystalline Co2P2O7 promoting the dissociation course of water molecules. The combination of crystalline and amorphous substances provides prospects for the design of HER catalyst structures in the future.

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