Refining the surface properties of WO2.7 by vacancy engineering and transition metals doping for enhanced alkaline hydrogen evolution reaction

Abstract

Anion-exchange membrane water electrolyzer is a promising and green technology for hydrogen production. However, the high energy barriers for the water dissociation step for breaking the strong H-O-H covalent bond results in sluggish hydrogen evolution reaction (HER) kinetics at the cathode. Herein, we present a strategy to optimize the morphology and surface properties of WO2.7 by introducing oxygen vacancies and doping with various transition metals. The experimental analysis demonstrates that the developed Co-WO2.7-x and Ni-WO2.7-x with ultrafine nanorods structure provide a larger electrochemical surface area than the other synthesized catalysts. Furthermore, theoretical analysis reveals that Co-WO2.7-x has the lowest energy barrier (0.65 eV) for the water dissociation step, which is much lower than that of WO2.7 (2.61 eV). Consequently, the Co-WO2.7-x delivers a current of 10 mA cm(-2) at a small overpotential of 59 mV for alkaline HER.