Synthesis of MoS2 nanosheet supported Z-scheme TiO2/g-C3N4 photocatalysts for the enhanced photocatalytic degradation of organic water pollutants

Abstract

MoS₂ nanosheets loaded with Z-scheme TiO₂/g-C₃N₄ photocatalysts were prepared using a wetness impregnation method. Exfoliated two-dimensional g-C₃N₄ and MoS₂ nanosheets were used for Z-scheme nanocomposite preparation. Structural, morphological, and photo-physical properties of the prepared photocatalysts were investigated using various spectroscopy and microscopy techniques. Few-layer MoS₂ loaded Z-scheme TiO₂/g-C₃N₄ photocatalysts exhibited extended absorbance in the visible region compared to other photocatalysts. The photocatalytic degradation of methylene blue, a common dye, and atrazine, a potent herbicide, in aqueous media were investigated using both pure and composite Z-scheme photocatalysts. 10 wt% g-C₃N₄ loaded-TiO₂ showed higher degradation performance than the other g-C₃N₄-loaded and bare photocatalysts. This degradation enhancement was due to the improved electron/hole pair separation at the TiO₂/g-C₃N₄ interface imparted by the Z-scheme electron transfer. Furthermore, MoS₂ nanosheets loaded with Z-scheme TiO₂/g-C₃N₄ photocatalysts exhibited superior degradation performance compared to all other photocatalysts. Few-layer MoS₂ co-catalyst, as an electron acceptor/accelerator, in the Z-scheme composite photocatalyst increased the photocatalytic activity. Suitable mechanism was proposed for this enhanced charge separation performance using PL analysis and band potentials of photocatalysts. The pathway of atrazine degradation was investigated using LC/MS/MS, and a possible degradation mechanism was proposed.