Seeding-induced construction of N-doped TiO2-bronze@g-C3N4 two-dimensional binary nanojunctions with enhanced photocatalytic activity

Abstract

Nitrogen-doped TiO₂-bronze@g-C₃N₄ (TiO₂ (B)@g-C₃N₄) two-dimensional binary heterojunctions were constructed based on seeding-induced growth through a microwave-assisted solvothermal process and subsequent thermal treatment in a vacuum. The morphology of the TiO₂ (B) nanosheets could be controlled by tuning the concentration of the Ti precursor, which determined the enhanced photoelectron activity. The optimal photocatalytic activity for the degradation of methyl orange (MO) under low-intensity visible-light illumination was obtained at a TiO₂ (B)/g-C₃N₄ molar ratio of 1 : 1, which was 12.7 and 7.9 times higher than that of pure g-C₃N₄ and P25, respectively. The photocatalytic activity was further enhanced by about 7.7% after in situ N-doping. The improvement in photocatalytic activity of N-doped TiO₂ (B)@g-C₃N₄ hetero-nanojunctions was attributable to the strong absorption in the visible-light region and better separation of photogenerated electron–hole pairs at the nanojunction interface, a result due to the large contact area between N-doped TiO₂ (B) and g-C₃N₄ nanosheets. We have explained the photocatalytic degradation of MO molecules largely in terms of the direct oxidation by the photogenerated holes and partly by the contribution of the superoxide radicals.