BiVO ₄ /BiFeO ₃ 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 Fe 3+ to form Fe 2+ by photoelectrons (e – ), thereby enabling the sustained generation of reactive oxygen species (ROS) for pollutant removal. In this study, a BiVO 4 /BiFeO 3 (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 Fe 2+ for H 2 O 2 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 Fe 3+ /Fe 2+ cycle and broadens the application of Fenton technology in the field of environmental remediation.