Activating and optimizing MoS2 basal-plane via spontaneous oxidation for enhanced photocatalytic hydrogen generation

MoS2 is a promising photocatalyst for hydrogen evolution reaction (HER), but its performance is still poor when used directly as a photocatalyst, due to its poor conductivity and high carrier recombination ratio. Here, through first-principles calculations, we find that spontaneous oxidation of the base plane can optimize the photocatalytic performance of MoS2. The MoS2−xOx crystal formed by spontaneous oxidation on the base plane results in an order of magnitude difference in electron-hole effective mass, and the electrostatic potential difference caused by symmetry breaking further promotes the effective separation of electron-hole pair, thus optimizing the photocarrier recombination rate of MoS2. In addition, with the increase of the degree of spontaneous oxidation, MoS2 bandgap continues to decrease, improving the intrinsic conductivity and visible light utilization. By comparing the REDOX potential of water splitting and the relative position of the band-edge in the neutral environment, the conduction band-edge of MoS2−xOx can meet the energy level requirements of photocatalytic HER until the doping concentration is 12.5%, and the high hydrogen production capacity has been reserved. Therefore, MoS2−xOx formed by spontaneous oxidation is an efficient and convenient photocatalyst with potential application prospect.