Interface engineering of in−situ formed nickel hydr(oxy)oxides on nickel nitrides to boost alkaline hydrogen electrocatalysis

Abstract

Highly efficient platinum−group−metal (PGM) free catalysts for alkaline hydrogen oxidation reaction (HOR) are of vital issues for the development of alkaline hydroxide exchange membrane fuel cells (HEMFCs). Herein, with the help of interface engineering by the in−situ electrochemical surface reconfiguration strategy, the seamless nickel nitrides-nickel hydr(oxy)oxide (denoted as Ni3N−Ni(OH)2) heterostructures were developed. From the systematic electrochemical measurements, the impressive HOR performance such as nearly zero onset overpotential, larger exchange current density, excellent long−term durability, and robust CO tolerance in alkaline media, are obtained by the optimized Ni3N−Ni(OH)2 catalyst, thus rendering it significant potential for applications in HEMFCs. Furthermore, this catalyst also exhibits superior HER activity, approaching to that of Pt/C catalyst. The tailored d band center of Ni and the enhanced hydroxyl adsorption ability at Ni3N−Ni(OH)2 heterojunctions are evidenced by the comprehensive spectroscopy and electrochemical analyses, which are favorable for the accelerated Volmer step toward alkaline hydrogen electrocatalysis.