Construction of solid–liquid interfacial Fenton-like reaction under visible light irradiation over etched CoxFeyO4–BiOBr photocatalysts

Abstract

In this study, we constructed an in situ Fenton-like photocatalytic system driven by visible-light irradiation. First, BiOBr, a benign in situ H₂O₂ producer, was prepared via a simple hydrothermal method. Then, the accelerant (CoFe₂O₄ nanoparticles as the precursor) for H₂O₂ decomposition was loaded onto the surface of the BiOBr photocatalyst to build a well-contacted interface for reactive sites. Co_xFe_yO₄ nanoparticles etched to different extents were obtained by adjusting the solution pH (pH = 1, 3 and 7) during the composite preparation process. A group of green and efficient Co_xFe_yO₄–BiOBr photocatalysts (abbreviated as CFB) (pH = 1, 3 and 7) were successfully synthesized. The optimal CFB material used for BPA photodegradation was 0.5% CFB (pH = 3). The reaction rate constant of 0.5% CFB (pH = 3) was 3.4 times higher than BiOBr (pH = 3). H₂O₂ detection, ESR and radical trapping experiments demonstrated that much of the H₂O₂ produced by BiOBr (pH = 3) was successfully decomposed to ˙O₂⁻ and ˙OH, which played important roles with h⁺ in the BPA photodegradation process, thereby a possible photocatalytic mechanism was proposed. Cycling experiments indicated the good stability of 0.5% CFB (pH = 3). This work may offer a green and efficient method for in situ H₂O₂ generation and decomposition, thus, the secondary pollution and harsh conditions of the conventional Fenton reaction can be tactfully avoided.