Interfacial charge transfer dynamics in S-scheme Cu2O/SnS2 heterojunction for enhanced photocatalytic degradation of organic pollutants

Photocatalytic degradation is a promising method for alleviating water pollution by utilizing solar energy and molecular oxygen as an oxidant. In this study, we synthesized an n-p type Cu 2 O/SnS 2 composite with an S-scheme heterojunction structure and investigated its photocatalytic degradation performance on methyl orange dye. Nano-cubic Cu 2 O particles are uniformly distributed on SnS 2 nanoflowers, forming a tight S-scheme heterojunction that facilitates rapid separation and transfer of photogenerated carriers. Superoxide radicals and holes play crucial roles in the photocatalytic degradation of methyl orange. Oxygen adsorption experiments reveal the adsorption behavior on the S-scheme heterojunction surface and its impact on photocatalytic performance. At a copper-to-tin ratio of 3:1, the Cu 2 O/SnS 2 composite achieved the highest catalytic activity under xenon lamp irradiation, with a methyl orange degradation rate of 97 % within 75 min and over 93 % after four cycles. The first-order reaction rate constant was significantly higher than those of Cu 2 O and SnS 2 . This study provides valuable insights into the design of efficient photocatalytic materials for environmental applications.