[Fabrication of the Heterojunction Photocatalyst MoS/BiOI and Its Investigation of Its Photocatalytic Reduction and Oxidation Activities].

Based on a two-step approach, a flower-like MoS/BiOI composite with a heterojunction has been successfully fabricated. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared MoS/BiOI. The formation mechanism of this heterostructure was investigated. The valence band (VB) and conduction band (CB) of the MoS/BiOI heterojunction have been calculated based on electrochemical characterization, implying the formation of a type I band alignment. The photodegradation of Rhodamine B (RhB) and Cr were used to assess photocatalytic reduction and oxidation activities. The results show that the MoS/BiOI composite structures perform much better than pristine MoS and BiOI. Among the composites with various MoS contents, 2% MoS/BiOI exhibits the best efficiency with respect to the degradation of RhB. After irradiation for 20 minutes, the degradation rate of RhB was 98.82%, which is 1.79 times higher than that using pure BiOI. After irradiation for 80 minutes, the removal of Cr was 97.87%, which is 3.85 times higher than that using pure BiOI. Holes and·O are the main reactive species during the photocatalytic process of RhB degradation; holes play the leading role.