Silver iodide decorated ZnSn(OH)6 hollow cube: Room-temperature preparation and application for highly efficient photocatalytic oxytetracycline degradation

ZnSn(OH)6 has been widely used in the photocatalytic field due to unique face-centered-cube structure and the full hydroxyl groups on the surface, but is still unsatisfied because of its wide band gap. Herein, a novel AgI/ZnSn(OH)6 hollow cube nanocomposite (AgI/ZSH) with superior visible-light-driven photocatalytic activity was prepared by a simple and room temperature synthesis method for overcoming these defects. The experimental and density functional theory (DFT) theoretical calculations illustrated that AgI nanoparticles loaded ZSH hollow cube can significantly enhance light absorption and accelerate the transfer of charges because of the special hollow structure of ZSH as well as suitable band gap between AgI and ZSH. The AgI/ZSH photocatalyst presented superior degradation effect for oxytetracycline hydrochloride (OTC). The degradation rate of AgI/ZSH increased by 26.31% and 93.36% compared with AgI and ZnSn(OH)6, respectively. The influences of initial OTC concentrations, pH, coexistence ions, and water sources were discussed in detail. Results showed that the photocatalyst is adapted to different environments. The excellent photo-stability of the product was confirmed by the basically unchanged degradation rate after four cycles. ESR and radical trapping experiments were employed to certify superoxide radical (O2−) and holes (h+) as the main active species. The degradation products and possible pathways of OTC were obtained through LC-MS/MS and the possible degradation mechanism was analyzed. This discovery provides an excellent approach for the synthesis of high-efficiency composite materials with non-spherical hollow structures under room temperature conditions for the degradation of antibiotics.