Highly efficient In 2 S 3 /WO 3 photocatalysts: Z-scheme photocatalytic mechanism for enhanced photocatalytic water pollutant degradation under visible light irradiation.

A Z-scheme system In 2 S 3 /WO 3 heterojunction was fabricated via a mild hydrothermal method and further applied for photocatalytic degradation of tetracycline (TCH) and Rhodamine B (Rh B) under visible light irradiation. The morphological structure, chemical composition and optical properties were studied by XRD, SEM, HRTEM and UV-visible absorption spectra. The results revealed that In 2 S 3 /WO 3 hierarchical structures were successfully constructed, and the prepared In 2 S 3 /WO 3 photocatalysts exhibited enhanced visible-light absorption compared to pure WO 3 nanorods, which are essential to improve the photocatalytic performance. The degradation rate of TCH using the In 2 S 3 (40 wt%)/WO 3 heterostructure (WI40) photocatalyst was about 212 times and 22 times as high as that for pure WO 3 and pure In 2 S 3 , respectively. The degradation rate of Rh B with the WI40 photocatalyst was about 56 times the efficiency of pure WO 3 and 7.6 times that of pure In 2 S 3 . The results of the surface photovoltage (SPV), transient photovoltage (TPV) and reactive oxidation species (ROS) scavenger experiments indicated that the Z-scheme system of In 2 S 3 /WO 3 is favorable for photoexcited charge transfer at the contact interface of In 2 S 3 and WO 3 , which benefits the charge separation efficiency and depresses the recombination of photoexcited charge, resulting in favorable photocatalytic pollutant degradation efficiency under visible light irradiation.