Construction and photocatalytic degradation of CdS-WO3 S-scheme heterojunction modified by CQDs

A CdS-WO 3 S-scheme heterojunction material modified by CQDs was constructed through simple methods, which effectively increases the photocatalytic degradation rate of single CdS. In the composite material, CdS acts as a reducing photocatalyst (RP) and WO 3 acts as an oxidizing photocatalyst (OP), forming an S-scheme heterojunction. In order to solve the photocorrosion problem of CdS, carbon quantum dots (CQDs) were loaded onto CdS. The CQDs possess a high work function, enabling them to facilitate electron transfer, enhance the migration of photogenerated carriers, and suppress electron-hole pair recombination, thus improving photocatalytic performance. The characterizations of XRD, TEM, element mapping, and XPS confirmed the successful synthesis of the CQDs-CdS-WO 3 composite. The material not only exhibited a photocatalytic degradation efficiency of 89.7% and 58.8% towards norfloxacin and tetracycline, respectively, but also revealed a certain degradation capability toward methylene blue and methyl orange. The primary active substances relevant in this degradation process are h + , 1 O 2 , H 2 O 2 , • O 2 − , and • OH. After multiple cyclic experiments, the material still maintains stable crystalline structure and degradation activity. Therefore, the successful preparation of this composite material provides a new method for photocatalytic decomposition of antibiotics and organic dyes.