Construction of SrTiO₃/CaIn₂S₄ S-scheme heterojunction for enhanced photocatalytic degradation of organic pollutants

Stable and efficient photocatalysts are the key to effective degradation of refractory organic compounds in wastewaters. In this article, the novel SrTiO₃/CaIn₂S₄ composites were successfully produced by a facile oil-bath method. The mechanism of S-scheme heterojunction formation, photogenerated carrier migration and photocatalytic reactions are described by a series of characterizations. The experimental conclusion shows that the SrTiO₃/CaIn₂S₄ S-scheme heterojunction has ability to efficiently degrade MO solutions, which outperformed that of pristine SrTiO₃ and CaIn₂S₄. The prepared SrTiO₃/CaIn₂S₄-7% composite showed the best photocatalytic activity, with 96% degradation of MO within 10 min. As demonstrated by free radical trapping experiments, the ·O₂⁻ is the major active reactant in the degradation of MO solutions. This study provides an idea for future design of efficient photocatalysts.