Constructing NiWO4/In2S3 hetero-junction to promote photo-generated carriers separation for enhancing photo-catalytic performance

Semiconductor photo-catalysis is a reliable solution in settling environmental pollution and energy shortage, but the single-phased semiconductors generally have low catalytic efficiency due to the ultra-fast recombination of photo-generated electron-hole pairs. The construction of hetero-junction is a popular and effective strategy to enhance photo-catalytic performance. Herein, the NiWO4/In2S3 hetero-junction was successfully prepared through chemical precipitation and hydrothermal two-step method. The structure and morphology of samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Meanwhile, not only the X-ray photoelectron spectroscopy (XPS) was used to confirm the formation of hetero-junctions, but also the diffuse reflectance spectroscopy (DRS) and photo-electrochemical tests were used to characterize the capacity of optical absorption and the photo-generated carrier separation. The photo-catalytic performances of all samples were assessed by rhodamine B (RhB) degradation, potassium dichromate (Cr6+) reduction and hydrogen production. Results indicated that NiWO4/In2S3 hetero-junction exhibited better photo-catalytic performance than those of NiWO4 and In2S3. Z-scheme charge transfer mechanism of NiWO4/In2S3 hetero-junction was suggested based on the results of trapping and electrochemical experiments.