CdS-dots decorated WO3 nanorods photocatalyst with highly ordered interfacial structure for enhanced photocatalytic activities via Z-scheme mechanism

Constructing heterostructure is regarded as one of the most promising strategies for the enhancement of photocatalytic activities, because it can make charge carriers separated more efficiently at the interface. Herein, CdS-WO₃ heterostructure photocatalysts with highly ordered and intimate interfacial structure between the two constituent phases have been successfully prepared via a heterogeneous nucleation and growth of CdS nanoparticles on the surface of WO₃ nanorods, which were fulfilled through a controlled release of S^2? in the aqueous solution containing Cd²⁺ by the reaction of NH₃ with thioacetamide. The as-prepared photocatalysts were carefully studied in morphology and interfacial structure by FESEM and HRTEM, along with the other characterizations by XRD, XPS, and UV–visible absorption spectra. Under the irradiation of mercury lamp, the photocatalyst with 6 wt% CdS could afford a degradation rate of methyl orange (MO) of 94.6% in 70 min, 5.84 and 2.51 times as high as WO₃ and CdS, through a photocatalytic degradation process mainly controlled by·O₂^? as active species. In view of the distinctive alignment of energy bands of CdS-WO₃, the enhanced photocatalytic activities should be attributed to the more efficient Z-scheme mechanism that allows the photogenerated holes in WO₃ and electrons in CdS to function more efficiently thanks to the efficient interfacial recombination of the electrons in WO₃ and holes in CdS.