The adsorption properties and stable configurations of hydroxyl groups at Mo edge of MoS2 (100) surface

The adsorption properties of hydroxyl groups on catalysts have crucial effect on the catalytic performance in oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The adsorption and reaction behaviors of hydroxyl groups on pristine and S vacancy modified Mo edge of 2H–MoS2 (100) surface are investigated using the first principle calculations. It is found that the hydroxyl groups tend to be absorbed at the stable sites rather than react with each other within a certain range from the Mo edge of MoS2. Increasing coverage of hydroxyl groups at Mo atoms weakens the interaction between pre-absorbed hydroxyl groups and Mo atoms, but hydroxyl groups don't react with each other. When the coverage of hydroxyl groups at Mo atoms reaches one hundred percent, a following hydroxyl group reacts with pre-adsorbed hydroxyl group and forms H2O molecule. Magnetic moment of MoS2 can be controlled from 4.3 μB to 1.79 μB by the hydroxyl group adsorptions, but the metallic property of the substrate cannot be changed. Single hydroxyl group adsorbed at S vacancy is more stable than that on pristine surface. These results provide an important reference for the adsorption properties of hydroxyl groups on the Mo edge of MoS2 (100) surface, thus it can be better used in the design and development of MoS2-based bifunctional or trifunctional catalysts.