Hematite-based photoanodes decorated with oxygen-deficient CeO2 for photoelectrocatalytic degradation of tetracycline: a pulse deposition strategy

The development of photoanodes with stable photoelectrocatalytic (PEC) performance is crucial to solve the secondary pollution caused by powder-based catalysts in antibiotic removal. In this study, FTO-α-Fe₂O₃@CeO₂ photoanodes were prepared using a short-time effective electrochemical pulse deposition method for PEC degradation of antibiotics. Based on the outstanding light absorption capability conferred by the narrow bandgap of α-Fe₂O₃, the separation advantage of photogenerated carriers conferred by the unique oxygen vacancies of CeO₂ and the variable polymetallic ion valence states (Fe²⁺/Fe³⁺, Ce³⁺/Ce⁴⁺), the target photoanode could achieve 93.13% degradation efficiency for tetracycline (TC) within 120 min. Ion leaching after degradation was controlled at an environmentally friendly level, and the universality was evaluated in configuration solutions from actual water. The matched Z-type heterojunction energy band structure and synergistic interaction between α-Fe₂O₃ and CeO₂ enhanced the catalytic efficiency of the photoanode, and the main contribution was attributed to the generation of the free radical ·OH and active species h⁺. Furthermore, cyclic voltammetric characteristic curves and Tafel curves demonstrated the advantages of the FTO-α-Fe₂O₃@CeO₂ photoanode in terms of stability and reaction kinetics. Ultimately, more complete TC degradation pathways were proposed based on the 13 intermediates detected, and the toxicity of the intermediates was assessed. This work enriched the development of catalytic photoanodes and provides new ideas for antibiotic removal involving non-powder catalysts.