Theoretical Investigation on Hydrogen Evolution Reaction Mechanism at MoS2 Heterostructure: The Essential Role of 1T/2H Phase Interface
Mixed 1T and 2H phases of MoS2 exhibits excellent catalytic activity for hydrogen evolution reaction (HER) in recent experiments. However the essential role played by 1T/2H phase interface is still obscure. Herein, periodic density functional theory (DFT) calculations have been performed to study the HER mechanism at two types of 1T/2H phase interface of MoS2 (“Zigzag” and “Armchair”). By analyzing the free energy of the adsorption atomic hydrogen (ΔGH) as the descriptor, we suggest that the optimum evolution of H2 proceeds at ∼10% H coverage for “Zigzag” and “Armchair” interfaces. Under this H coverage, the Volmer−Tafel mechanism is the dominant reaction path for both two interfaces, in which the Volmer reaction is the rate determining step, and HER would proceed more easily at “Zigzag” interface with lower energy barriers. Our results indicate that the HER process along the 1T/2H phase interface exhibits comparable activity with the Mo-edge of 2H MoS2 and the basal plane of 1T MoS2. In addition, we investigate the effect of the metal (Fe, Co, Ni, and Zn) and non-metal (N, P, and O) dopants for “Zigzag” type interface, and propose that the HER activity could be improved by doping with Ni for interfacial Mo atom or with N for interfacial S atom.