Promoted electron transfer in Fe2+/Fe3+ co-doped BiVO4/Ag3PO4 S-scheme heterojunction for efficient photo-Fenton oxidation of antibiotics

Abstract

A Fe2+/Fe3+ co-doped BiVO4/Ag3PO4 S-scheme heterojunction catalyst was synthesized by a simple hydrothermal method and applied to achieve efficient photo-Fenton for antibiotics degradation (99.70 %). The co-doping of Fe3+/Fe2+ highlighted red shift of optical absorption edge (535–800 nm) and adjustable band structure of BiVO4/Ag3PO4. The collaborative system of photocatalytic and Fenton could maintain high catalytic activity and stability in the treat of simulated actual water and high efficiency within wide pH conditions (3–7). The degradation experiments were employed to show removal efficiency on tetracyclines and quinolones antibiotics including tetracycline (TC), ciprofloxacin (CIP), doxycycline (DO), levofloxacin (LEV), norfloxacin (NOR), and enrofloxacin (ENR). Mechanism exploration elaborated that the m-FBVO/APO composites with dominant Fe2+ preserved both high oxidation potential (<−0.33 eV vs NHE) and reduction potential (>2.45 eV vs NHE) through the constructed BiVO4/Ag3PO4 S-scheme heterojunction. Efficient e−/h+ pairs separation was further achieved through Fe3+/Fe2+ pairs cycling. And degradation pathway of TC was mainly investigated to verify its mineralization. This work provides a new sight towards catalytic mechanisms in heterogeneous photo-Fenton degradation systems.