One-pot preparation of a novel CoWO4/ZnWO4 p-n heterojunction photocatalyst for enhanced photocatalytic activity under visible light irradiation

The photocatalytic degradation of organic wastewater is a very promising strategy due to its high efficiency and no secondary pollution. Herein, the synthesis of a CoWO4/ZnWO4 p-n heterojunction and the photocatalytic removal of RhB has been reported. Characterization of the photocatalysts using XRD, FTIR, XPS, SEM and TEM confirmed that ZnWO4 nanoparticles were successfully attached to the CoWO4 nanosheets. More importantly, CZW-3 prepared with a CoWO4/ZnWO4 ratio of 1:3 displayed the highest photocatalytic activity, degrading RhB at a rate of 93% over 40 min, which is approximately 1.3-fold higher than pure ZnWO4. The creation of p-n heterojunctions, which strengthen the transmission of photogenerated carriers, is primarily responsible for the high photocatalytic activity observed. During the degradation process, the •O2− is the most important reactive species. Furthermore, a plausible photocatalytic mechanism has been discussed.