Interface coupling to improve O adsorption and accelerate charge separation for boosting photocatalytic performance of ZnO/ZnInS composite in HO production and environmental remediation.

The key to heterogeneous photo-Fenton technology lies in the efficient generation of hydrogen peroxide (HO). Herein, a newly-designed ZnO/ZnInS composite with heterostructure is synthesized. Benefiting from the formation of built-in electric field, the recombination of photoinduced electrons and holes is suppressed and interfacial charge transfer resistance is reduced. Importantly, the embedding of ZnO in ZnInS can improve the hydrophobicity and create microscopic three-phase interface, thereby boosting the capture capability for O and providing the convenience for the occurrence of O reduction reaction. More interestingly, the existence of ZnInS in the ZnO/ZnInS composite can reduce the Gibbs free energy (ΔG) of key intermediate (OOH*) formation, which will accelerate the generation of HO. As a result, the ZnO/ZnInS composite displays excellent performance in photocatalytic HO production, and the highest yield was about 897.6 μmol/g/h within 60 min under visible light irradiation. The transfer of photoinduced carriers follows the S-scheme type mechanism. The photogenerated holes can be captured by drug residues (i.e., diclofenac sodium) to accelerate HO production, while generated HO can combine with Fe to construct photo-Fenton system for achieving the advanced degradation of diclofenac sodium, which was mainly related to the formation of OH. Furthermore, generated HO can be applied for performing the inactivation of pathogenic bacteria. In short, current work will provide a valuable reference for future research.