A novel 3D/2D CdIn2S4 nano-octahedron/ZnO nanosheet heterostructure: facile synthesis, synergistic effect and enhanced tetracycline hydrochloride photodegradation mechanism

In this work, 3D CdIn2S4 nano-octahedron/2D ZnO nanosheet heterojunctions (CIS/ZO-x) were fabricated for the first time via a facile and green impregnation–hydrothermal method, where three-dimensional (3D) CdIn2S4 nano-octahedra densely anchor onto both sides of 2D ZnO nanosheets to form an embedded nanostructure with intimate interfacial contacts. Various characterization techniques were adopted to measure the morphologies, structures and optical properties of the as-prepared CIS/ZO-x heterojunctions in detail. The photocatalytic performance of the as-prepared CIS/ZO-x was evaluated via the photodegradation of tetracycline hydrochloride (TCH) under visible light irradiation, and the result shows that the hybridization of ZnO nanosheets with CdIn2S4 nano-octahedra significantly enhances the photocatalytic activity of heterojunctions. The highly stable and reusable sample CIS/ZO-2 possesses the highest photocatalytic activity (94.04%), and its rate constant (k = 0.06357 min−1) is about 4.96 and 22.31 times as high as those of pure CdIn2S4 and ZnO. Interestingly, the removal efficiency of TCH and the rate constant are also much higher than those of numerous previously reported composite photocatalysts. The synergistic effect and the unique 3D/2D hybrid structure with intimate interfacial contacts are primarily responsible for the enhanced photocatalytic activity. A possible photocatalytic mechanism for the TCH photodegradation over the CIS/ZO sample is also proposed. This work provides a novel 3D/2D composite photocatalyst for the efficient removal of antibiotic pollutants and will be helpful for designing other 3D/2D heterojunctions.