Microwave solvothermal synthesis of cubic MnS@Ag2S core-shell photocatalysts with improved charge separation and photocatalytic activity

Abstract Cubic α-MnS and core-shell MnS@Ag2S photocatalysts were successfully synthesized with a microwave-assisted solvothermal and ion-exchange approach. The morphology, phase, crystal/optical properties, charge separation and photocatalytic H2 generation activity of these photocatalysts were studied. The morphology of these MnS nanomaterials can be tuned from microsphere to microcubes by altering the reaction temperature and duration. A HRTEM image of the MnS@Ag2S photocatalyst reveals that the surface of cubic MnS is decorated with uniformly distributed Ag2S nanoparticles. The formation of Ag2S shell can effectively increase the carrier separation and photocatalytic activity of MnS-based photocatalysts. The rate of hydrogen production of the MnS@Ag2S photocatalyst becomes 2548 μmol g−1 h−1, which is 3.7 times that of the MnS photocatalyst. Mn L3-edge near-edge X-ray-absorption fine-structure (NEXAFS) spectra were monitored in situ before and after exposure to light to investigate the interfacial charge-transfer behaviors within the MnS@Ag2S photocatalysts. The results confirm that photogenerated electrons transfer from MnS to Ag2S.