Construction of Highly Efficient Zn0.4Cd0.6S and Cobalt Antimony Oxide Heterojunction Composites for Visible-Light-Driven Photocatalytic Hydrogen Evolution and Pollutant Degradation

Abstract

Photocatalytic technology could effectively degrade pollutants and release hydrogen. Herein, novel composite materials of Zn0.4Cd0.6S (ZCS) and cobalt antimony oxide (CSO) with different proportions were successfully synthesized through a hydrothermal reaction process. It was proved via various characterization analyses that abundant nano ZCS particles (about 100 nm) were closely coated on the surface of larger CSO particles in the composite photocatalysts, and the heterojunction structure was formed. The synthesized materials could be used as highly efficient photocatalysts to boost the photocatalytic hydrogen evolution and degradation of methylene blue (MB) in visible light. The composite photocatalysts displayed favorable stability, and the optimal proportion was ZCS/1CSO. In addition, the composite materials exhibited a wider absorption range for visible light, and the apparent hydrogen production rate was about 3.087 mmol·g−1·h−1. Meanwhile, compared with single materials, the composite photocatalyst obtained higher photocurrent response and lower electrochemical impedance through conducting photo-electrochemical experiments and analysis. Moreover, all of the photo-generated electrons, superoxide radicals, photo-generated holes, and hydroxyl radicals were proved to contribute the MB photodegradation and hydrogen evolution, and the former two active species played more vital roles. Furthermore, the effective separation of photo-generated electrons and holes through the n-type of ZCS and p-type of CSO heterojunction structure accelerated the improvement of photocatalytic abilities for composite materials. The photo-generated electrons concentrated in the conduction band of ZCS might be helpful for the improvement of hydrogen evolution abilities of composite photocatalysts. This work not only provides a novel strategy towards high-efficiency composite photocatalysts through constructing heterojunction assisted with hydrothermal reaction, but also demonstrates the possibility of utilizing binary composites for enhanced hydrogen evolution reaction and pollutant degradation.