Surface functionalization of bulk MoS2 sheets for efficient liquid phase exfoliation in polar micromolecular solvents

The booming progresses of two-dimensional molybdenum disulfide (2D-MoS2) in diverse fields have often been hindered by the limited preparation. Liquid phase exfoliation (LPE) is the most common technology for the massive preparation of 2D-MoS2 nanosheets. However, the high boiling points, toxic and hard to remove solvents used in LPE are the biggest obstacle to 2D-MoS2 practical applications. Here we modified the surface property of bulk MoS2 crystals to be preferentially hydrophilic by non-covalent absorption of the anionic molybdates on the surface of MoS2 sheets. The results demonstrated that the dispersibility of bulk MoS2 sheets was changed completely and the 2D-MoS2 nanosheets with an average lateral size of about 90 nm and high crystallinity were obtained from the exfoliation of functionalized MoS2. The thickness is fewer than ten layers, of which monolayer account for 15%. The optimized yields were 1.7% in pure water, 2.3% in methanol, 4.6% in ethanol, and 10.1% in isopropanol. The as-prepared 2D-MoS2 nanosheets can be directly used for electrocatalytic hydrogen evolution exhibit potential application value. This work provides a novel and effective strategy for changing the dispersibility of MoS2 sheets and promoting the versatile preparation of 2D-MoS2 nanosheets in polar micromolecular solvents without any surfactant.