Interface engineering in ternary Cu4SnS4 nanocrystals decorated CNTs for boosting photocatalytic degradation performance

In order to solve the problems of carrier recombination and low catalytic performance of a single semiconductor photocatalytic material, a composite photocatalytic material of ternary semiconductor materials Cu₄SnS₄ (CTS) nanocrystals (NCs) and carbon nanotubes (CNTs) was synthesized. To investigate the effect of the interface on the catalytic performance, we treated CNTs with dopamine (Pdop) salts and further embedded CTS in them to form CTS-CNTs@Pdop composites. CTS-CNTs degraded 88.2 % of Sudan Red (III) after 2 h of illumination compared with 37.2 % of pure CTS and 68.2 % of CTS-CNTs@Pdop. The main reason for the enhanced photocatalytic performance is that the addition of CNTs enhances the carrier transport separation, while the presence of a dopamine interlayer with poor conductivity inhibits the transport and separation of carriers, which indicates the importance of interfacial contacts between the two active materials. Three models, Schottky junction, thin Metal-Insulator-Semiconductor (MIS) junction and thick MIS junction, were used to explain these results in detail.