Enhanced photocatalytic activity for 4-nitrophenol degradation using visible-light-driven In2S3/α-Fe2O3 composite

Highlights: • The In₂S₃/α-Fe₂O₃ heterostructures were synthesized by a simple two-step method. • The heterostructures exhibited enhanced visible-light photocatalytic activity. • The heterostructures improved the stability of pure In₂S₃. • The Z-scheme system in In₂S₃/α-Fe₂O₃ boosted photocatalytic performance. In₂S₃/α-Fe₂O₃ composites were synthesized using the methods of hydrothermal treatment and reflux. Characterization such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Photoluminescence (PL) was used to characterize the crystallinity and morphology of the composites, which proved the successful synthesis of the In₂S₃/α-Fe₂O₃ heterostructures. The 4-nitrophenol (PNP) degradation experiments by visible light were studied to evaluate the photocatalytic activity of the In₂S₃/α-Fe₂O₃ composites. The composites showed much higher photocatalytic degradation activities and TOC removal rate than both pure In₂S₃ and α-Fe₂O₃. The PNP degradation rate of composites was about 4.7 and 11.9 times that of pure In₂S₃ and α-Fe₂O₃, respectively. The degradation process was detected by high performance liquid chromatography and mass spectrometry, and the degradation pathway was explained. Based on the trapping experiments, e⁻ and • OH were the main active species and a Z-scheme photocatalytic mechanism of In₂S₃/α-Fe₂O₃ was proposed, which showed the double advantage of high redox ability and efficient electron-hole pairs separation.