Rationally designed Ni2P/WS2/Co9S8@C multi-interfacial electrocatalyst for efficient overall water splitting

Exploring cost-efficient electrocatalysts for water electrolysis is imperative and urgent. Herein, we have successfully synthesized the novel Ni2P/WS2/Co9S8@C electrocatalyst with the multi-heterojunction interfaces via pyrolysis and in situ phosphorization processes by employing high-nuclearity metal clusters {Co24W8} as preassembly molecular platform. As expected, Ni2P/WS2/Co9S8@C exhibits outstanding oxygen evolution and hydrogen evolution performances with ultralow overpotentials of 204 mV and 67 mV at 10 mA cm−2 in alkaline media, respectively. The alkali-electrolyzer using Ni2P/WS2/Co9S8@C as cathode and anode electrodes delivers a low cell voltage of 1.48 V achieving 10 mA cm−2 with good durability. Density functional theory calculations suggest that the interfacial electrons transfer from Co9S8 and Ni2P to WS2 obviously lower the binding energies of adsorbed species and thus enhance their intrinsic activity. This work demonstrates unique advantages of interfacial structure modulation for the rational design of high-performance bifunctional electrocatalysts.