Fabrication of a hybrid phase TiO2/g-C3N4 heterojunction composite with enhanced adsorption and photocatalytic degradation of MB under visible light

Abstract

The heterojunction structure of semiconductor photocatalysts is significant for making full use of their capabilities for organic molecules and dye degradation. In this paper, we present a heterogeneous junction composite fabricated with hybrid phase TiO₂ and g-C₃N₄ for methylene blue (MB) removal through adsorption and photocatalytic degradation. The heterogeneous junction system was prepared by hydrothermal treatment with a subsequent pyrolysis process. The variation of the proportion and lattice structure of hybrid phase TiO₂ in the synthesized catalysts was analyzed by refinement. Adsorption experiments showed that the maximum adsorption capacity of TiO₂/g-C₃N₄ (1 : 10) was 1667 mg g⁻¹, which was 45.97 times and 63.78 times higher than that of TiO₂ and g-C₃N₄, respectively. In the photodegradation process, the TiO₂/g-C₃N₄ (1 : 10) photocatalyst shows a removal rate of MB of 100 mg L⁻¹, which was as high as 96.262%, significantly higher than that of pure TiO₂ and g-C₃N₄. Brunner–Emmett–Teller (BET) measurements and Fourier transform infrared spectroscopy (FTIR) showed that the adsorption of MB onto TiO₂/g-C₃N₄(1 : 10) was chemical adsorption, and ˙OH, which acts as an active substance, was found to play a major role in the photocatalytic degradation process. Overall, the developed hybrid phase TiO₂/g-C₃N₄ heterojunction composite may be beneficial for the treatment of water pollution.