Light-assisted synthesis MoSx as a noble metal free cocatalyst formed heterojunction CdS/Co3O4 photocatalyst for visible light harvesting and spatial charge separation

In this paper, a novel photocatalyst with visible light harvesting and spatial charge separation is reported, in which cobalt oxide (acting as a hole trap) and molybdenum sulfide (acting as an electron trap) are assembled on the surface of cadmium sulfide nanorods. The MoSx/CdS/Co3O4 composite photocatalyst shows a high H-2 evolution with a yield of 537.51 mu mol in 5 h, which is 35.53 times greater than over pristine CdS (15.13 mu mol). The detailed underlying reason was comprehensively studied and understood by means of SEM, TEM, XRD, XPS, UV-vis DRS, BET; in particular, investigation of their photoelectro-chemical properties with photocurrent, voltammetric scanning, fluorescence spectra etc. The high photocurrent response, the lower overpotential (-0.37 V vs. SCE), the faster electron transfer rate constant (k(ey) = 4.23 x 10(9) s(-1)) and the short fluorescence lifetime (0.457 ns) supported the efficient spatial charge transfer between CdS and MoSx as well as Co3O4. The simultaneous loading of bicocatalysts can significantly improve the photo-induced spatial charge separation of CdS because MoSx nanoparticles act as an electron trap to rapidly transfer electrons from CdS while Co3O4 acts as a hole trap to quickly transfer holes, enhancing its photocatalytic performance as well.