S-Vacancy Defect and Transition-Metal Atom Doping to Trigger Hydrogen Evolution of Two-Dimensional MoS<sub>2</sub>
Yanggu Liu, Shoujie Guan, Xuesen Du, Yanrong Chen, Yang Yang, Kunlu Chen, Ziwen Zheng, Xing Wang, Xiaoqiang Shen, Chenlong Hu, Xinbao Li
Abstract
Two-dimensional (2D) MoS 2 is commonly used as an anode catalyst for electrochemical water splitting. However, the limited active edge sites of 2D MoS 2 have hindered its electrochemical performance in electrochemical water splitting. Here, experimental outcomes and density functional theory (DFT) calculations demonstrate that the catalytic performance of inert 2D MoS 2 surfaces can be triggered by doping transition-metal atoms and introducing S-vacancies. In this work, the catalytic activity of different metal-doped (Cu, Mn, and Nb) 2D MoS 2 with S-vacancies shows a great difference among tested MoS 2 -based samples. Characterizations verify the existence of dopant ions and S-vacancies. In particular, the Cu-doped electrocatalyst exhibits a low overpotential of 197 mV at 10 mA cm –2 in an acidic solution and superior stability of less than 10 mV increase in overpotential after 12 h of continuous hydrogen production process, proving that Cu doping and introduced S-vacancies can benefit the electrochemical performance. Moreover, DFT calculations reveal that S-vacancies and the further introduction of different metal ions can alter the adsorption behavior of H atoms by changing the d-band center of the in-plane Mo site neighboring the doped heteroatom atoms and S-vacancy sites, which explains well the superior performance of Cu-doped 2D MoS 2 .