Highly efficient solution exfoliation of few-layer molybdenum disulfide nanosheets for photocatalytic hydrogen evolution.

Two-dimensional (2D) molybdenum disulfide (MoS) has drawn increasing attention due to its great potential for advanced electronics, photonics, optoelectronics, energy storage, catalysis and solar cell. However, high effective exfoliation for the mass production of 2D MoS is still a challenge. To improve the exfoliation efficiency of MoS nanosheets, a facile liquid-phase exfoliation strategy has been developed by using organic electrolyte solutions in this work. It is shown that the dispersion concentration of MoS nanosheets has been significantly enhanced in organic electrolyte solutions. For example, by adding sodium tartrate into dimethyl sulphoxide, the dispersion concentration of MoS nanosheets is 85 times that in neat dimethyl sulphoxide. About 80% of MoS nanosheets obtained in such a strategy is 1-4 layers and the nanosheets remain 2H phase structure. In addition, the photocatalytic hydrogen evolution performance of the as-prepared few-layer MoS nanosheets is evaluated. The photocatalytic hydrogen evolution rate is as high as 0.5 mmolg h, which is 71 and 10 times higher than that of bulk MoS and the 2H-MoS nanosheets, respectively, reported to date. Exfoliation mechanism investigation suggests that the size of cation and the intensity of Lewis basicity of anion in the salts have played an important role in the exfoliation of MoS. The liquid exfoliation strategy reported here has great potential in the large-scale and high quality production of few-layer MoS nanosheets for efficient photocatalytic hydrogen evolution.