Visible-light-responsive Z-scheme heterojunction MoS2 NTs/CuInS2 QDs photoanode for enhanced photoelectrocatalytic degradation of tetracycline

Abstract

A direct Z-scheme heterojunction coupling hierarchical nanosheet MoS2 nanotubes with CuInS2 quantum dots was successfully prepared to fabricate MoS2 NTs/CuInS2 QDs photoanodes for enhanced photoelectrocatalytic (PEC) activity. The MoS2 NTs with stacked nanosheets and tubular structure have high surface area and abundant basal edges, which can create more active reaction sites. Simultaneously, the continuous and broad photo-absorption range of MoS2 NTs improved the utilization of visible-light and increased the separation efficiency of photo-induced electron-hole pairs. The integration of MoS2 NTs with CuInS2 QDs onto Cu foil yielded direct Z-scheme heterojunction photoanode. The formation of Z-scheme heterojunction inhibited the recombination of photo-induced electron-hole pairs and produced more active electrons and holes to facilitate the generation of highly active species. Under visible light illumination, the prepared MoS2 NTs/CuInS2 QDs photoanode showed superior PEC activity by applying a suitable bias voltage. In PEC process, the generated holes, hydroxyl radicals and superoxide radicals with strong oxidative were employed to achieve highly efficient degradation of tetracycline. The prepared photoanode exhibited high stability, reusability, and broad application potential in PEC degradation of organic pollutants. Moreover, a possible mechanism of the transfer pathway of photo-induced electron-hole pairs on the MoS2 NTs/CuInS2 QDs photoanode was proposed based on a direct Z-scheme heterojunction.