In this study, ZnCo_2S_4 (ZCS) nanoparticles were coupled on the surface of TiO_2 by simple solvothermal method to form S-scheme heterojunction. Compared with ZCS and TiO_2, the photocatalytic performance of ZCS/TiO_2 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 TiO_2 and ZCS, respectively. Moreover, ZCS/TiO_2 also has excellent performance in the photocatalytic degradation of tetracycline (TC). The enhancement of photocatalytic performance of ZCS/TiO_2 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/TiO_2. 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.
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