Liquid-exfoliation of layered MoS₂ for enhancing photocatalytic activity of TiO₂/g-C₃N₄ photocatalyst and DFT study

Highlights: • MoS₂ nano-sheets were obtained by Liquid-Exfoliation technique. • TiO₂/g-C₃N₄/MoS₂ composites were synthesized by solvothermal method. • The formation mechanism of TiO₂/g-C₃N₄/MoS₂ was studied by DFT method. • The electron-transfer of photocatalyst was discussed at a molecular cluster level. - Abstract: A new combined method of liquid-exfoliation and solvothermal process was employed for synthesizing TiO₂/g-C₃N₄/MoS₂ photocatalysts. In this typical process, the MoS₂/g-C₃N₄ nano-sheets was prepared by liquid-exfoliation method from the bulk MoS₂ and bulk carbon nitride in the alcohol system, and then the TiO₂ nanoparticles (NPs) were grown on the MoS₂/g-C₃N₄ nano-sheets by in-situ synthesis technique. The evaluation of photocatalytic degradation reaction showed that the as-prepared TiO₂/g-C₃N₄/MoS₂ photocatalysts exhibited higher photocatalytic activity as compared to the pure TiO₂, pure g-C₃N₄ and TiO₂/g-C₃N₄ composite. The enhanced photocatalytic activities of TiO₂/g-C₃N₄/MoS₂ photocatalysts are attributed to positive synergetic effect of heterostructure between g-C₃N₄/MoS₂ hybrid and TiO₂ nano-structure, which not only enlarged spectral response and also enhanced the utilization rate of photons. Furthermore, DFT (Density Functional Theory) was employed to investigate the formation mechanism of the interfaces between TiO₂ NPs and g-C₃N₄/MoS₂ nano-sheets, which would be of great importance in revealing the electron-transfer at the interfaces of composites and the mechanism for the great improvement for the activity of TiO₂/g-C₃N₄/MoS₂ photocatalysts.