Visible-light-driven CdS/ZnS heterojunctions with excellent photocatalytic performance for organic dyes removal

Photocatalytic technology is environmentally-friendly and energy-saving for degradating organic pollutants. Highly efficient and visible light response photocatalysts are vital for the excellent degradation performance. In the work, CdS/ZnS heterojunctions were fabricated via low-heat solid-state chemical method and the photocatalytic activity was systematically studied. When the molar ratio of ZnS to CdS was 9:1, the CdS/ZnS heterojunctions exhibited the highest photocatalytic activities, and 99% and 58% of methyl orange were degraded under UV and visible light, respectively. Besides, 91% and 94% of rhodamine B and tetracycline were degraded under UV light, respectively. The outstanding photocatalytic performances of CdS/ZnS heterojunctions were attributed to the enhanced light absorption and the fast migration of carriers, which were verified by UV visible diffuse reflection absorption spectrum, surface photocurrent, and fluorescence spectrum. In addition, on the bases of free radical trapping experiment and theoretical calculation, a possible photocatalytic mechanism was put forwards. The study provides a new idea for the design of highly efficient and wide spectral responsive photocatalysts.