In situ construction of layered K₃Ti₅NbO₁₄/g-C₃N₄ composite for improving visible-light-driven photocatalytic performance

A simple calcination approach was performed to synthesize layered K₃Ti₅NbO₁₄/g-C₃N₄ (TNCN) composites, in which g-C₃N₄ was formed both within the interlayers and on the surface of N-K₃Ti₅NbO₁₄. The photocatalytic activity of samples was evaluated by the visible-light photocatalytic degradation of rhodamine B (RhB). It was found that TNCN composite with a proper mass ratio of N-K₃Ti₅NbO₁₄ to g-C₃N₄ exhibited the rapid rate of charge separation and high efficiency of light harvesting due to the synergetic effects of layered heterojunction and N doping, leading to an excellent photocatalytic activity. Especially, the in situ intercalated mono-layered g-C₃N₄ nanosheets can significantly increase the contact area between K₃Ti₅NbO₁₄ layers and g-C₃N₄ nanosheets for efficient charge transfer across the interface, showing the greater effect on the enhanced photocatalytic activity. The active species trapping experiments and ESR measurements were carried out to evaluate the contribution of the active species in this photocatalytic degradation process. It was revealed that both superoxide radicals (^·O₂⁻) and holes (h⁺) are the main active species, while hydroxyl radicals (^·OH) made a minor contribution to the photocatalytic degradation of RhB.