Controlled exfoliation of monodispersed MoS2 layered nanostructures by a ligand-assisted hydrothermal approach for the realization of ultrafast degradation of an organic pollutant

Abstract

Molybdenum disulfide (MoS₂) layered nanosheets were synthesized by the hydrothermal method. Citric acid was used as an organic ligand to obtain the monodispersed layered MoS₂ nanostructures. The effect of citric acid on the formation and functional properties of the layered MoS₂ nanostructures was investigated. The X-ray diffraction patterns revealed the formation of a hexagonal crystal structure of MoS₂. Significant peak shift was observed for the interaction of citric acid and Mo in the core level spectra of X-ray photoelectron spectroscopy. Citric acid-free hydrothermal growth resulted in the formation of micron-sized MoS₂ nanospheres, whereas citric acid-assisted hydrothermal growth resulted in the formation of well dispersed layers of MoS₂, confirmed by morphological analysis. However, the highest concentration of citric acid resulted in the formation of aggregated layers. The obtained MoS₂ nanostructures were used as photocatalysts to decompose methylene blue (MB) as a model pollutant. The obtained results showed that the MoS₂ layered nanosheets could effectively decompose the organic pollutant. The MB absorption peaks completely disappeared after 24 min of irradiation when using the nanosheets synthesized with a citric acid concentration of 0.04 M. The effect of pH on the MoS₂ nanosheets was studied, and 96% MB degradation was observed at pH 12 after 2 min of visible-light irradiation.