Novel broad spectrum light responsive PPy/hexagonal-SnS2 photocatalyst for efficient photoreduction of Cr(VI)

Broad spectrum light response and high photo-carrier separation efficiency are two key postulates for promising photocatalysts. In this perspective, polypyrrole (PPy) modified hexagonal SnS₂ nanosheet composites were firstly designed via in-situ polymerization method and used for Cr(VI) reduction with broad spectrum light (UV–vis-NIR) driven. Results indicated that 15-PPy/SnS₂ composite material not only has good photocatalytic performance in the visible region (λ > 420 nm), but also has a great improvement in the visible (λ > 550 nm) and near-infrared (λ > 760 nm). With the analysis of EIS, PL and transient photocurrent responses, PPy can observably accelerate the separation of electrons-holes pair in the photocatalytic reaction. Trapping experiments indicated that e⁻ and O₂⁻ all played master roles in the photoreduction process. Based on the trapping experiments and the Mott-Schottky analysis, a possible mechanism is proposed. This work will provide a thinking to construct other SnS₂-based photocatalysts for efficient Cr(VI) reduction with full spectrum light utilization.