Construction of Honeycomb-like ZnO/g-C3N5 Heterojunction for MB Photocatalytic Degradation

In this study, a combination of calcination and hydrothermal methods was employed to synthesize a honeycomb-like ZnO/g-C3N5 (ZCN) heterojunction in situ. The ZCN heterojunction photocatalyst exhibits remarkable photocatalytic degradation performance, achieving a 97% methyl blue (MB) degradation rate with the rate constant of 0.0433 min−1 (almost twice that of ZnO). Optical performance tests reveal that the ZCN heterojunction broadens the absorption edge to 710 nm and enhances the charge carrier separation. The presence of abundant oxygen vacancies, as revealed by X-ray photoelectron spectroscopy analysis, effectively suppresses the recombination of photogenerated electron–hole pairs. Furthermore, density functional theory simulations indicate that the combination of ZnO and g-C3N5 creates an internal electric field due to their differing work functions. This leads to the formation of a Z-scheme heterojunction that effectively suppresses charge carrier recombination and preserves the strong redox capabilities of ZnO and g-C3N5. Finally, electron spin resonance results indicate that O2− and OH are the primary active radicals involved in the degradation process. This study introduces a potential approach for the development of highly efficient Z-scheme photocatalysts for water treatment applications.