CdS nanodots adorned (020)-featured WO3•H2O nanoplates heterojunction with augmented photocatalytic hydrogen production under Z-scheme charge transfer mechanism

In this paper, controllable nucleation and growth of CdS nanodots on the (020)-featured WO3 center dot H2O nanoplates has been successfully accomplished to prepare CdS-WO3 center dot H2O heterojunction with high-quality interfacial contact through a slow release of Cd2+ and S2- from the gradual self-loop hydrolysis of cadmium acetate and thioacetamide. The chemical and structural characteristics of as-prepared samples before and after heat treatment are detailedly investigated by TG-DSC, XRD, Raman, XPS, FESEM and HRTEM, as well as their light absorption performance from UV-Vis DRS. The maximum average hydrogen production rate for CdS-WO3 center dot H2O reaches 2.15 mmol.g(-1).h(-1) under 300 W Xe lamp irradiation (lambda > 420 nm) using lactic acid as sacrificial reagent, which is 8.27 and 2.72 times as much as CdS and CdS-WO3, respectively. According to band alignment, CdS-WO3 center dot H2O exhibits greater energy difference of Fermi level than CdS-WO3, and augmented photocatalytic performance should arise from efficient Z-scheme charge transfer mechanism under stronger built-in electric field, in which the conduction band electrons of WO3 center dot H2O and valence band holes of CdS are expected to effectively recombine at their interfacial zones, while the conduction band electrons of CdS and valence band holes of WO3 center dot H2O contribute to the reduction of H+ and oxidation of lactic acid.