Construction of in-situ carbon-doped TiO2 decorated Fe3O4 heterojunction and their enhanced photocatalytic oxidation of As(III) under visible light

Abstract

This paper is focused on the functional photocatalyst of in-situ carbon-doped TiO2 decorated Fe3O4 heterojunctions (C/TiO2@Fe3O4) for the efficient photocatalytic oxidation of As(III). Series of characterizations show that the photocatalytic activity of TiO2 changes from a single UV wavelength to visible light excitation when carbon atoms are successfully doped in the TiO2 lattice, expanding the utilization rate of light energy. DFT calculation further confirmed that the C–O–Ti bonds can diminish the theoretical band-gap of TiO2. Furthermore, the successful construction of C–O–Ti and Ti–O–Fe interface bonds provide pathways for fast electron transfermation, which can effectively prompt the separation of photo-generated carriers and enhance the photocatalytic oxidation efficiency of As(III). The application results showed that the synthesized C/TiO2@Fe3O4 photocatalyst by introducing Fe3O4 with a mass fraction of 1% can complete the transformation of As(III) (10,000 μg/L, 40 mL) to As(Ⅴ) within 12 min under visible light irradiation. In addition, C/TiO2@Fe3O4 exhibits excellent reusability, which remains 100% photooxidation efficiency of As(III) without changing crystal structure after 6 cycles and can also be recovered completely with magnet. The remarkable photocatalytic oxidation performances of C/TiO2@Fe3O4 can be ascribed to the synergistic effects of OH, O2− and h+ in the photocatalytic oxidation process and the constructed C–O–Ti and Ti–O–Fe interface bonds.