Fabrication of novel ternary direct Z-scheme + isotype heterojunction photocatalyst g-C3N4/g-C3N4/BiOBr with enhanced photocatalytic performance

Abstract A novel ternary direct Z-scheme + isotype heterojunction, Δ(Z + H)-scheme photocatalyst CN-TU/BiOBr was fabricated by an effective combination of thermal decomposition and solvothermal method. The samples of g-C3N4 prepared using urea, thiourea and thiourea-urea complexes as precursors were named CN-U, CN-T and CN-TU, respectively. In addition, CN-M was prepared by physically mixing CN-U and CN-T. The structure, morphology, optical and electronic properties of the prepared samples were characterized by XRD, FTIR spectra, SEM-EDS, BET, XPS and DRS. The photocatalytic activities of the synthesized samples were estimated by the degradation of Rhodamine B (RhB), Fluorescein isothiocyanate (FITC) and antibiotic tetracycline hydrochloride (TC) in the presence of visible light. Compared with other as-prepared samples, the ternary 1%CN-TU/BiOBr photocatalyst exhibited an excellent activity, which is attributed to the construction of the ternary Δ(Z + H)-scheme not only benefit to maintain outstanding redox capability of the electrons, but also facilitates the separation of photo-generated carrier. Furthermore, the stability of the sample is tested by cyclic experiments. This work will provided a new insight into optimizing the structure and designing similar Z-scheme photocatalytic system.