Photocatalytic hydrogen evolution and antibiotic degradation by S-scheme ZnCo2S4/TiO2

In this study, ZnCo2S4 (ZCS) nanoparticles were coupled on the surface of TiO2 by simple solvothermal method to form S-scheme heterojunction. Compared with ZCS and TiO2, the photocatalytic performance of ZCS/TiO2 under simulated sunlight is significantly improved, and its hydrogen evolution efficiency reaches 5580 μmol·g−1·h−1 with the apparent quantum efficiency (AQY) up to 11.5% at 420 nm, which is 88.3 times and 54.3 times that of TiO2 and ZCS, respectively. Moreover, ZCS/TiO2 also has excellent performance in the photocatalytic degradation of tetracycline (TC). The enhancement of photocatalytic performance of ZCS/TiO2 is mainly due to S-scheme heterojunction. On the one hand, the S-scheme electron transfer path not only improves the electron-hole separation efficiency, but also improves the charge transfer efficiency. On the other hand, ZCS significantly enhances the visible light absorption of ZCS/TiO2. The photocatalytic mechanism and S-scheme heterojunction structure is confirmed by XPS, EPR, ultraviolet photoelectron spectroscopy (UPS) and energy band structure. This work provides a new idea for designing and constructing S-scheme heterojunction to improve the performance of photocatalytic hydrogen evolution and TC degradation.