Synthesis of Zn Sn Cd S Solid Solutions for Photocatalytic Reduction of Cr(VI): Bandgap Structure and Sulfur Vacancy Regulation.

Ternary metal sulfides (TMSs) solid solutions have been regarded as ideal semiconductors in various photocatalytic reactions due to their outstanding redox reversibility, high electron conductivity, and great stability. In this work, a series of Zn Sn Cd S (ZSCS) solid solutions were synthesized by a simple hydrothermal method and applied in the photocatalytic reduction of Cr(VI). The Cr(VI) reduction efficiency of ZSCS-5 quickly reached nearly 100% within 3 min under visible light irradiation. The controlling of sulfur content in ZSCS induced the transformation of cubic to hexagonal CdS, regulating the energy band structure and sulfur vacancy (S ) content, both of which further influenced the redox properties of ZSCS samples. The more negative conduction band position and more sulfur vacancies contributed to the enhanced photocatalytic reduction performance of ZSCS-5 toward Cr(VI). The active species e , h , O ⋅ and O were all involved and h played a pivotal role in the photocatalytic reaction. This work provided an excellent photocatalyst for reduction of Cr(VI) and strongly confirmed the regulation of energy band structure and sulfur vacancies in photocatalysts through controlling the precursor content.