Crystallization of Amorphous Molybdenum Sulfide Induced by Electron or Laser Beam and Its Effect on H₂‑Evolving Activities

We report herein investigation on crystallization of amorphous molybdenum sulfide a-MoS_x induced by electron and laser beam resulting in formation of crystalline molybdenum disulfide c-MoS₂. This crystallization occurred in situ during transmission electron microscopic and Raman analyses of a-MoS_x material. It was also found that a-MoS_x to c-MoS₂ phase transformation was not fully beneficial for H₂-evolving catalytic performance. c-MoS₂ showed better robustness but significantly lower catalytic performance. Furthermore, c-MoS₂ was less tolerant to oxidation stress, as the one caused by photogenerated holes within the light harvester, compared with a-MoS_x catalyst. Thus, a-MoS_x is a better candidate for implementation within photocatalysts for overall solar water-splitting application.