Hydrothermal synthesis of Z-type SnO2 quantum dot-modified ZnO nanosheets with enhanced photocatalytic activity

SnO2 quantum dots, ranging from 10 to 30%, were combined with ZnO nanosheets to create a heterojunction photocatalyst. This composite was generated using a basic hydrothermal method, which was then followed by high-temperature calcination to enhance the photocatalytic activity of ZnO. The results showed that the synthesized SnO2 nanoparticles with tetragonal rutile phase and ZnO nanosheets with hexagonal fibrillar zincite phase, the coupling of SnO2 quantum dots and ZnO nanosheets improved the separation efficiency of the photogenerated carriers, and at the same time broadened the photoresponse range. Through the degradation of the organic dye Rhodamine B (RhB), the best photocatalytic activity was found at 20% amount of SnO2 in the composite sample (SZ-2), and the degradation efficiency of RhB reached 96.5% at the light irradiation time of 100 min. In addition, an in-depth study of the photocatalytic mechanism of the constructed heterojunction by active group trapping experiments, and the results showed that center dot O-2(-) and h(+) were the main active substances in this degradation system. Meanwhile, the SZ-2 photocatalyst was tested for five cycles, and the degradation efficiency of the 5th cycle was 72%. The cycle test indicates that the SZ-2 sample is highly stable and reusable. Therefore, the results showed that the prepared SnO2/ZnO heterojunction photocatalysts are suitable materials for degrading organic dyes.