BiVO4/BiFeO3 n-p Heterojunction for Efficient Photo-Fenton Tetracycline Removal under Visible-Light Irradiation

Heterogeneous photo-Fenton technology is an efficient advanced oxidation process for the removal of organic pollutants in water. This process accelerates the reduction of Fe3+ to form Fe2+ by photoelectrons (e-), thereby enabling the sustained generation of reactive oxygen species (ROS) for pollutant removal. In this study, a BiVO4/BiFeO3 (BVO/BFO) n-p heterojunction catalyst was obtained via calcination and wet chemical methods for tetracycline (TC) photo-Fenton removal. The optimal ratio of BVO:BFO was 0.7:1, which can achieve 70.08% TC degradation in 30 min (k = 0.0147 min-1), markedly surpassing bare BFO and BVO, and retaining >70% efficiency after ten cycles. The remarkable improvement of TC removal resulted from efficient electron-hole (e-/h+) pair separation by heterojunction in space to regenerate Fe2+ for H2O2 activation. Furthermore, two distinct TC degradation pathways induced by h+ and •OH were proposed, including dehydroxylation, demethylation, deamidation, ring opening, and hydroxylation. This study provides an insight into the acceleration of the Fe3+/Fe2+ cycle and broadens the application of Fenton technology in the field of environmental remediation.