Visible-light-driven Ag/AgCl@In2O3: a ternary photocatalyst for the degradation of tetracycline antibiotics

Abstract

The abuse of tetracycline antibiotics (TCs) has created great threats to both human health and the ecosystem. Therefore, developing efficient technologies to remediate these contaminants is of significant and practical interest. In this work, a ternary plasmonic Ag/AgCl@In₂O₃ nanocomposite was synthesized by growing AgCl on the surface of one-dimensional In₂O₃ nanorods, followed by the in situ photoreduction of Ag from AgCl on AgCl@In₂O₃. The as-synthesized Ag/AgCl@In₂O₃ nanocomposite exhibits excellent performance for the photocatalytic degradation of tetracycline (TTC) with a degradation rate constant of 0.166 min⁻¹, which is much better than that of pristine In₂O₃, Ag@In₂O₃, AgCl@In₂O₃, Ag/AgCl, and In₂O₃ + Ag/AgCl (the mechanical mixture of In₂O₃ and Ag/AgCl) samples. Five photocatalytic cycling tests demonstrate that Ag/AgCl@In₂O₃ possesses outstanding stability. In addition, Ag/AgCl@In₂O₃ also exhibits excellent photo-activity for the degradation of other types of tetracycline antibiotics, e.g. chlortetracycline (CTC) and oxytetracycline (OTC). Further trapping experiments prove that h⁺ and ˙O₂⁻ are responsible for the photocatalytic reactions. The enhancement in the photoactivity of the Ag/AgCl@In₂O₃ system is largely due to the surface plasmon resonance effect (SPR) provided by the Ag nanoparticles, which inject electrons into AgCl and/or In₂O₃, and the efficient separation of photoinduced carriers is possible by transferring electrons to the conduction band of In₂O₃. This work provides a new type of photocatalyst towards the effective treatment of tetracycline antibiotics in aqueous systems.