In situ hydrothermal growth of Ni-based hydrogen phosphate polyhedrons on Ni foam for efficient hydrogen evolution reaction

Abstract

Developing a cost-effective and stable electrocatalyst is the key to achieve the large-scale applications of water electrolysis to produce green hydrogen. Herein, an in situ hydrothermal growth strategy was put forward to prepare a novel self-supporting electrode, that is, Ni-based hydrogen phosphate polyhedrons supported on 3D Ni foam. This electrode was composed of crystalline (Ni(H2PO4)2·2H2O, Ni(H3P2O7)2·2H2O), and amorphous phase in which NiO nanoparticles formed. The amorphous phase connected polyhedrons to the Ni foam substrate, forming multifarious heterogeneous interfaces. Such a structure possessed large number of active sites, favored the fast reaction kinetics and electron transport rate, synergistically resulting in a superior alkaline HER performance. In alkaline electrolyte, the electrode only needed a small overpotential of 69 mV to reach the current density of 10 mA cm−2 with a small Tafel slope of 56 mV dec−1, and exhibited a good stability at the current density of 100 mA cm−2 for 50 h. This in situ hydrothermal growth strategy opened up a new route to green synthesis of cost-effective and stable 3D heterostructured self-supporting electrode for water-splitting.