Sulfur vacancies and Schottky heterojunction promote the photocatalytic H2 evolution of MnxCd1-xS: accelerated charge separation, rich active sites and decreased overpotential

This study adopted the solvothermal method to load non-precious metal Cu2MoS4 (CMS) co-catalyst onto Mn0.43Cd0.57S (MCS). MCS nanoparticles were closely attached on CMS nanosheets to build Schottky heterojunction for highly efficient H2 evolution. Due to their different Fermi levels, electrons occurred directional migration to form built-in electric field, which could accelerate carrier separation. Charge density difference and Bader charge results ascertained the migration direction and number of electrons. The addition of CMS endowed CMS/MCS with sulfur vacancies and a larger specific surface area, which leaded to richer active sites in the composite, enhancing the adsorption of H2O and the desorption of H2. Meanwhile, LSV results confirmed that 3CMS/MCS (-0.12 V) had the lower H2 evolution overpotential than that of pure MCS (-0.22 V), enhancing the H2 production in the kinetic aspect. Consequently, 3CMS/MCS possessed the highest photocatalytic H2 evolution rate (8233.63 μmol·g-1·h-1), which was 2.08 times that of MCS and even was 1.24 times that of MCS-Pt. After three cycles, 3CMS/MCS still remained the high stability. Ultimately, CMS co-catalyst promoted the photocatalytic performance of pure MCS by enhancing the carrier separation, enriching active sites and reducing the H2 evolution overpotential. This study might offer new insights for enhancing the photocatalytic H2 evolution performance of sulfide solid solution through bimetallic sulfides.