Construction of Core-shell Structured WO3@SnS2 Hetero-junction as a Direct Z-scheme Photo-catalyst

Abstract An ideal photocatalyst not only offers high photo-generated electron-hole pairs separation ability, but also has suitable redox potential. Here, a direct Z-scheme core-shell structured WO 3 @SnS 2 hetero-junction photo-catalyst was prepared via two-step hydrothermal method, in which the core-shell structure, rod morphology and micro-composition of hetero-junction were confirmed through X-ray diffraction (XRD) patterns, Fourier transform infrared (FTIR) spectra, field emission scanning electron microscope (FE-SEM), transmission electron microscope (FEI-TEM) and X-ray photoelectron spectra (XPS). Their enhanced photo-catalytic abilities were evaluated by photo-degradation of Rhodamine (RhB), photo-reduction of dichromate (Cr 6+ ) solution and photo-catalytic H 2 production through comparing with pure WO 3 , SnS 2 or the mixture of WO 3 and SnS 2 (WO 3 /SnS 2 ). The absorption spectra and electrochemical properties were used to estimate the band gap of samples, the expanded spectral absorption capacity and improved electron-hole separation ability, which are important factors for enhanced photocatalytic performance. Furthermore, the direct Z-scheme charge transfer mechanism of WO 3 @SnS 2 hetero-junction was determined through the combination of theoretical calculation and experimental characterizations, which played a decisive role for retaining excellent redox potential and increasing photo-catalytic ability of WO 3 and SnS 2 .