Construction of CdSe/ZnIn2S4 Z-Scheme heterojunction for enhanced photocatalytic degradation of tetracycline

ZnIn2S4 as an energy band narrow photocatalyst has attracted extensive attentions in water remediation, but the fast carrier recombination efficiency hinders its further utilization. An effective strategy is to boost photocarrier separation and enhance photocatalysis performance by building heterojunction. Here, a simple in-situ deposition method is used to create a unique CdSe/ZnIn2S4 heterojunction structure. By varying the CdSe content, CdSe/ZnIn2S4 composites can be synthesized with diffident photocatalytic properties. The optimal photocatalytic efficiency of CdSe/ZnIn2S4 composite is obtained when 1.0 % CdSe addition, while an overdose of CdSe QDs results in a deterioration of photocatalytic efficiency. 93 % tetracycline (TC) degradation could be attained. And the degradation rate is 1.9 and 2.3 times higher than pure ZnIn2S4 and CdSe. In addition, the CdSe/ZnIn2S4 photocatalytic mechanism complies with the Z-Scheme. In the photodegradation process, the superoxide radicals (center dot O-2(-)) and holes (h(+)) are the primary active agents.