Hydrogen peroxide-assisted photoelectrocatalytic degradation of tetracycline by ZnFe2O4-decorated TiO2 nanotube arrays

Photoactive materials with visible-light absorption have attracted considerable interest for the solar-driven photoelectrochemical (PEC) degradation of organic pollutants, particularly antibiotics. In this work, we develop a ZnFe2O4/TiO2 photoanode for the photoelectrochemical degradation of tetracycline (TC) under visible light, assisted by hydrogen peroxide (H2O2). The photoanode is prepared by hydrothermally decorating ZnFe2O4 nanoparticles onto TiO2 nanotube arrays (TNAs), where the ∼4 μm-long TNAs are first grown on Ti sheets via anodic polarization method. Under the optimized hydrothermal conditions (100°C for 12 h) for the growth of ZnFe2O4 on TNAs, the resulting photoanode exhibits a photocurrent density of 0.41 mA cm-2, achieving 67% TC degradation within 90 min. Upon the addition of a small amount of H2O2 (0.15%), the degradation efficiency increases to 95%, highlighting the role of reactive oxygen species generated through H2O2 decomposition, together with bias-induced charge separation, in enhancing the effectiveness of the proposed approach for removing organic pollutants from water. Kinetic studies further reveal that the rate constant of the H2O2-assisted PEC process (kobs) is 0.0347 min-1, which is 86.5 times higher than that for individual photolysis (∼4×10-4 min-1).