In situ construction of WNiM-WNi LDH (M = Se, S, or P) with heterostructure as highly efficient electrocatalyst for overall water splitting and urea oxidation reaction.

Abstract

Electrochemical water splitting as an important means of obtaining high purity hydrogen fuel has attracted great interest. In this study, the structural engineering of complex WNiM-WNi LDH (M = Se, S, or P) was firstly developed by in situ growth on Ni foam for use in overall water splitting and the urea oxidation reaction. These WNiM-WNi LDH (M = Se, S, or P) catalysts exhibit outstanding electrocatalytic performance in the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and urea oxidation reaction (UOR), respectively. An overpotential of only 64 mV of OER is required for WNiS-WNi LDH and 126 mV of HER is required for WNiP-WNi LDH to achieve 10 mA cm-2. The WNiSe-WNi LDH materials display a particularly outstanding performance for UOR, requiring a potential of 1.25 V to drive 10 mA cm-2. Moreover, the optimized WNiS-WNi LDH as an anode and WNiP-WNi LDH as a cathode can achieve 10 mA cm-2 at a low cell voltage of 1.45 V in 1 M KOH solution for overall water splitting. The density functional theory calculations show that the introduction of the NiP2 and WP material greatly reduces the Gibbs free energy of the hydrogen adsorption of the material.