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 ZnFe 2 O 4 /TiO 2 photoanode for the photoelectrochemical degradation of tetracycline (TC) under visible light, assisted by hydrogen peroxide (H 2 O 2 ). The photoanode is prepared by hydrothermally decorating ZnFe 2 O 4 nanoparticles onto TiO 2 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 ZnFe 2 O 4 on TNAs, the resulting photoanode exhibits a photocurrent density of 0.45 mA cm -2 , achieving 67% TC degradation within 90 min. Upon the addition of a small amount of H 2 O 2 (0.15%), the degradation efficiency increases to 95%, highlighting the role of reactive oxygen species generated through H 2 O 2 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 H 2 O 2 -assisted PEC process ( k obs ) is 0.0347 min -1 , which is 86.5 times higher than that for individual photolysis (0.004 min -1 ).