A Novel Route to Manufacture 2D Layer MoS₂ and g-C₃N₄ by Atmospheric Plasma with Enhanced Visible-Light-Driven Photocatalysis

An atmospheric plasma treatment strategy was developed to prepare two-dimensional (2D) molybdenum disulfide (MoS₂) and graphitic carbon nitride (g-C₃N₄) nanosheets from (NH₄)₂MoS₄ and bulk g-C₃N₄, respectively. The moderate temperature of plasma is beneficial for exfoliating bulk materials to thinner nanosheets. The thicknesses of as-prepared MoS₂ and g-C₃N₄ nanosheets are 2-3 nm and 1.2 nm, respectively. They exhibited excellent photocatalytic activity on account of the nanosheet structure, larger surface area, more flexible photophysical properties, and longer charge carrier average lifetime. Under visible light irradiation, the hydrogen production rates of MoS₂ and g-C₃N₄ by plasma were 3.3 and 1.5 times higher than the corresponding bulk materials, respectively. And g-C₃N₄ by plasma exhibited 2.5 and 1.3 times degradation rates on bulk that for methyl orange and rhodamine B, respectively. The mechanism of plasma preparation was proposed on account of microstructure characterization and online mass spectroscopy, which indicated that gas etching, gas expansion, and the repulsive force of electron play the key roles in the plasma exfoliation. Plasma as an environmentally benign approach provides a general platform for fabricating ultrathin nanosheet materials with prospective applications as photocatalysts for pollutant degradation and water splitting.