Fabrication of a novel p–n heterojunction photocatalyst n-BiVO4@p-MoS2 with core–shell structure and its excellent visible-light photocatalytic reduction and oxidation activities

The novel p–n heterojunction photocatalyst n-BiVO4@p-MoS2 with core–shell structure was successfully fabricated for the first time through a facile in-situ hydrothermal method, in which MoS2 shell thickness was easily tuned by varying the concentration of MoS2 precursor in the solution. The photocatalytic performances of samples were systematically investigated via the photocatalytic reduction of Cr6+ and oxidation of crystal violet (CV) under visible-light irradiation. The BiVO4@MoS2 samples exhibited excellent photocatalytic performance, among which, the BiVO4@MoS2 (10 wt%) sample with MoS2 shell 300 nm thickness, showed the highest photoreduction and photooxidation activities. The enhanced photocatalytic activities could be attributed to the suppression of charge recombination, the high specific surface area and strong adsorption ability toward the pollutant molecule, and the enhanced or tunable light absorption of BiVO4@MoS2. Especially, the core–shell structure geometry also increases the contact area between BiVO4 and MoS2, which facilitates the charge transfer at the BiVO4/MoS2 interface. The photocatalytic mechanism of BiVO4@MoS2 for reduction of Cr6+ and oxidation of CV was discussed in detail. Moreover, 12 photocatalytic degradation intermediates and products of CV were also identified by the gas chromatography–mass spectrometer (GC–MS).