Tailoring the oxygen vacancies and electronic structures of the hex-WO3 (100) crystal plane with heteroatoms for enhanced hydrogen evolution performance
Haishun Jiang, Wen‐Jie Chen, Xu Wang, Honglin Ma, Yi Li, Jing Tang
Abstract
Due to the difficulty of developing noble materials for large-scale applications, transition metal oxide materials have become popular alternatives for the hydrogen evolution reaction. However, compared to commercial Pt/C, poor conductivity and hydrogen evolution activity are common for transition metal oxides, including WO 3-x -based semiconductors, so it is therefore necessary to ameliorate the electrode self-properties to be suitable for H 2 production. Here, different ratios of S 2- and Ni 2+ salts are introduced into hexagonal WO 3 and Ni 0.4 WO 3-x S x is prepared successfully after oxygen vacancies and W O S and Ni–W-O bonds are formed on the surface of the Ni 0.4 WO 3-x S x nanorods . The X-ray photoelectron, Raman and electrochemical impedance spectroscopy results show that the incorporation of Ni and S atoms can increase the number of oxygen vacancies and the conductivity for hydrogen evolution, simultaneously demonstrating that the W O S and Ni W O bonds are the main active sites of the Ni 0.4 WO 3-x S x nanorods . Density functional theory calculations further indicate that the ΔG H* of NiWO 3-x S x is closer to 20 % commercial Pt/C. The Tafel slope reduces to 87.3 mV/dec when approaching the Volmer–Heyrovsky kinetic mechanism reaction. Finally, the onset potential is 53 mV. The overpotential is 173 mV at 10 mA/cm 2 , which is 68 % lower compared to hexagonal WO 3 .