Construction of direct-Z-scheme heterojunction photocatalyst of g-C3N4/Ti3C2/TiO2 composite and its degradation behavior for dyes of Rhodamine B

Abstract

Direct-Z-scheme g-C₃N₄/Ti₃C₂/TiO₂ photocatalyst with giant internal electric field was prepared by one-step aqueous sonication self-assembly method using g-C₃N₄ and MXene of Ti₃C₂ as the source materials. The chemical composition and structure of the catalysts was characterized by FT-IR, XRD, SEM, TEM, and XPS. The XPS characterization indicated that Ti₃C₂ was partially oxidized to TiO₂ during the composite process. As a result, an efficient direct-Z-scheme heterojunction structure consisting of the g-C₃N₄ and TiO₂ with Ti₃C₂ as an electron bridge was constructed. The photocatalytic performance of the prepared catalysts was evaluated by degrading the rhodamine B (RhB) wastewater. Compared with the single g-C₃N₄, the g-C₃N₄/Ti₃C₂/TiO₂ composite photocatalyst exhibited efficient and stable photocatalytic degradation ability, with a degradation efficiency as high as 99.2% for RhB under optimal conditions (2% Ti₃C₂, pH = 3). The high degradation performance of g-C₃N₄/Ti₃C₂/TiO₂ for RhB was attributed to the combination of Ti₃C₂, TiO₂, and g-C₃N₄ components, forming a direct-Z-scheme heterojunction with a high-speed electron transport channel structure. The role of Z-scheme heterojunctions in electron transport is verified by photoelectrochemical characterization, along with photoluminescence (PL). Our research provides a simple method to design photocatalysts by constructing direct-Z-scheme electron transport channels for highly efficient treatment of dye wastewater.