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 In2S3/WO3 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 In2S3/WO3 hierarchical structures were successfully constructed, and the prepared In2S3/WO3 photocatalysts exhibited enhanced visible-light absorption compared to pure WO3 nanorods, which are essential to improve the photocatalytic performance. The degradation rate of TCH using the In2S3(40 wt%)/WO3 heterostructure (WI40) photocatalyst was about 212 times and 22 times as high as that for pure WO3 and pure In2S3, respectively. The degradation rate of Rh B with the WI40 photocatalyst was about 56 times the efficiency of pure WO3 and 7.6 times that of pure In2S3. The results of the surface photovoltage (SPV), transient photovoltage (TPV) and reactive oxidation species (ROS) scavenger experiments indicated that the Z-scheme system of In2S3/WO3 is favorable for photoexcited charge transfer at the contact interface of In2S3 and WO3, which benefits the charge separation efficiency and depresses the recombination of photoexcited charge, resulting in favorable photocatalytic pollutant degradation efficiency under visible light irradiation.