Efficient fabrication of MoS2 nanocomposites by water-assisted exfoliation for nonvolatile memories

Abstract

Efficient and green exfoliation of bulk MoS₂ into few-layered nanosheets in the semiconducting hexagonal phase (2H-phase) remains a great challenge. Here, we developed a new method, water-assisted exfoliation (WAE), for the scalable synthesis of carboxylated chitosan (CC)/2H-MoS₂ nanocomposites. With facile hand grinding of the CC powder, bulk MoS₂ and water followed by conventional liquid-phase exfoliation in water, this method can not only efficiently exfoliate the 2H-MoS₂ nanosheets, but also produce two-dimensional (2D) CC/2H-MoS₂ nanocomposites. Interestingly, the intercalated CC in MoS₂ nanosheets increases the interlayer spacing of 2H-MoS₂ to serve as good candidates for the semiconductor devices. 2D CC/2H-MoS₂ nanocomposites show superior electronic rectification effects in nonvolatile write-once-read-many-times memory (WORM) behavior with an ON/OFF ratio over 10³, which can be rationally controlled by the weight ratios of CC and MoS₂. These findings by the WAE method would open tremendous potential opportunities to prepare commercially available semiconducting 2D nanocomposites for promising high-performance device applications.