In-situ Synthesis of SnO2 Quantum Dots/ZnS Nanosheets Heterojunction as a Visible-light-driven Photocatalyst for Degradation of Rhodamine B, Potassium Dichromate and Tetracycline

The SnO 2 quantum dots (SnO 2 QDs)/ZnS nanosheets (ZnSNs) heterojunction was fabricated via an in-situ synthetic method at room temperature. Rhodamine B, potassium dichromate, and tetracycline were used to discuss the photocatalytic activities of the as-prepared samples under the visible light illumination. The photocatalytic mechanism of the as-prepared samples was also proposed. The experimental results indicate that the degradation efficiency of the as-prepared SnO 2 QDs/ZnSNs heterojunction first increases and then decreases with increasing the usage of ZnSNs. When the mass ratio of SnO 2 QDs to ZnSNs is 1: 2 in 180 min, the asprepared samples have the highest degradation efficiency of 89.1% for rhodamine B, 97.7% for potassium dichromate, and 83.8% for tetracycline, which are much higher than 51.7%, 26.8%, and 0.9% of pure SnO 2 QDs as well as 37.9%, 87.1%, and 19.1% of pure ZnSNs, respectively. After it is repeatedly degraded for 3 times, it possesses the degradation efficiency of 62.5% for rhodamine B, which increases by 200.5% in comparison with 20.8% of the pure SnO 2 QDs. Moreover, the enhanced photocatalytic performances of the as-prepared hybrids are attributed to the formation of heterojunction between the SnO 2 QDs and ZnSNs. In addition, hydroxyl radicals and superoxide anion radicals play major roles during the photocatalytic degradation process, while holes play a minor role.