Effect of oxygen doping on the hydrogen evolution reaction in MoS2 monolayer

Molybdenum disulphide (MoS2) monolayer is regarded as one of the most promising non-noble metal electro-catalysts for hydrogen evolution reaction (HER). Increasing the catalytic active sites in MoS2 monolayer is critical for further improvement of catalytic behaviour. In this paper, the effects of oxygen (O) doping on the HER of MoS2 monolayer were investigated by using the density functional theory. The results showed that the O-doping assists in the formation of S and Mo vacancies. The hydrogen adsorption free energy is greatly reduced from 2.18 eV on pristine MoS2 monolayer to -0.01 eV on MoS1.96O0.04 and MoS1.88O0.12 monolayers with S vacancies. The Gibbs free energies for hydrogen adsorption on MoS1.92O0.08 and MoS1.84O0.16 monolayers with Mo vacancies are 0.02 and -0.02 eV, respectively. These results provide a general design methodology to increase hydrogen production in the electrochemical reaction of MoS2 monolayer by defect engineering. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.