Highly efficient visible-light-driven water splitting for H2 evolution and degradation of ECs using CdS/ZnIn2S4 S-scheme heterojunction with built-in electric field

Environmental pollution and energy shortage are two major challenges facing humanity today. Photocatalytic technology, as a green and sustainable approach, is an important choice for effectively addressing these challenges. The formation of S-scheme heterojunctions and built-in electric fields can significantly improve the transfer and separation of photoinduced charge carriers, hence enhancing the efficiency of photocatalytic reactions, which is greatly significant for improving the performance of photocatalysts. In this study, a photocatalyst CdS/ZnIn₂S₄ with a built-in electric field, which is an S-scheme heterojunction photocatalyst, was prepared by a simple solvothermal method. CdS/ZnIn₂S₄ exhibited efficient visible-light-driven H₂ evolution from water, with a rate of 4.09 mmol g^-1h⁻¹, 3.60 and 2.80 times higher than that of CdS and ZnIn₂S₄, respectively, and an apparent quantum efficiency (AQE) of 2.71 %. Moreover, it also showed performance in visible-light-driven degradation of various ECs, achieving degradation rates of 82.2 %, 80.9 %, and 81.5 % for tetracycline, ciprofloxacin, and norfloxacin, respectively, within 40 min. It was confirmed that the successfully constructed S-scheme heterojunction can effectively separate photoinduced electron-hole pairs and suppress their recombination. The built-in electric field inside the composite material can effectively promote the movement of photoinduced charge carriers, thereby promoting the course of photocatalytic reactions. This study is positively significant for the development of novel efficient photocatalysts, exploration of new methods for environmental pollution control, and development of green hydrogen energy.