In situ synthesis of novel 0D/ 2D SnO2 nanoparticles/ SnS2 nanosheets S-scheme heterojunction for enhancing the photocatalytic pollutant degradation

0D/2D SnO2/SnS2 S-scheme heterojunction with close contact interface was successfully constructed by in-situ growth of SnO2 nanoparticles on SnS2 nanosheets with a two-step hydrothermal method under electrostatic attraction. SnO2/SnS2 composite with molar ratio of 1:2 shows the excellent photocatalytic performance for the reduction of Cr(VI) (98.4% for 40 min) and the degradation of methyl orange (99.1% for 70 min) under visible light irradiation. The apparent rate constant for Cr(VI) reduction is about 66.7, 7.6, and 4.5 times higher than those of SnO2, SnS2, and physical mixed samples, respectively. The experimental and theoretical calculation results reveal that the charge transfer mechanism of SnO2/SnS2 conforms to S-scheme heterojunction. With the help of built-in electric field, band bending, and Coulomb gravity, SnO2/SnS2 S-scheme heterojunction has high redox ability and strong separation efficiency of photogenerated carriers. This work provides a new approach for in-situ preparation of novel S-scheme SnO2/SnS2 heterojunction photocatalysts for environmental remediation.