Defective non-homogeneous bismuth-based photocatalysts with (Bi0S/Bi0I)-VBi-VO charge transfer channels for efficient water disinfection

Development of plasma-defect pair-modified photocatalysts with high performance present a significant advance in photocatalytic water disinfection. Here, we report the synthesis of Bi/Bi₁₂SiO₂₀/Bi₂O₂SiO₃/Bi₂WO₆/BiOBr/BiOI (BBWSBI) photocatalysts incorporating surface and interfacial plasma Bi⁰ (Bi⁰_S/Bi⁰_I), Bi vacancies (V_Bi), and oxygen vacancies (V_O). The as-prepared BBWSBI exhibits near-complete degradation of Rhodamine B (Rh B) within 30 min and achieved an inhibition rate of approximately 100 % against Escherichia coli (E. coli) within 1 h under simulated sunlight, outperforming most previously documented Bi-based photocatalysts. Density Functional Theory (DFT) and in situ X-ray Photoelectron Spectroscopy (XPS) identified an efficient charge transfer pathway in a type-II/(type-Z/type-Z)/type-Z heterojunction as follows: conduction band (CB) → V_Bi → Bi⁰_I → valence band (VB) (←Bi⁰_S) → V_O. This pathway significantly improved the charge separation efficiency of the photocatalyst. Additionally, the photocatalytic degradation mechanisms were explored via liquid chromatography–mass spectrometry, revealing that Bi⁰_S-V_Bi-V_O promoted pollutant molecule adsorption and activation. This study offers a new approach to constructing charge transfer pathways in water disinfection photocatalysts through the incorporation of plasma defect pairs.