Photocatalytic enhancement mechanism of direct Z-scheme heterojunction O-g-C3N4@Fe-TiO2 under visible-light irradiation

Abstract

A novel visible-light response heterojunction photocatalytic catalyst was developed in this study. The fragmented O-g-C3N4 discontinuously coated on the surface of Fe-TiO2, which exhibited excellent photocatalytic activity, photocatalytic stability and long-term durability under visible light irradiation. Compared with pristine O-g-C3N4 and Fe-TiO2, the photocatalytic degradation efficiency of O-g-C3N4@Fe-TiO2 was 1.32 and 1.65 times higher than that of the former two, respectively. Compared with the electrically neutral Fe-TiO2, the electronegative O-g-C3N4 demonstrated excellent adsorption capacity for the cation MB+. The proper band structure of the element-doped O-g-C3N4 and Fe-TiO2 catalysts ensured the absorption capacity of visible light by O-g-C3N4@Fe-TiO2. The Z-scheme transfer mechanism of photo-generated carriers in O-g-C3N4@Fe-TiO2 was constructed, which could not only promote the separation of holes in the valence band of Fe-TiO2 and the electrons in the conduction band of O-g-C3N4 effectively, but also could retain the holes and electrons with stronger redox abilities in the O-g-C3N4@Fe-TiO2 catalyst.