Size-controlled MoS nanosheet through ball milling exfoliation: parameter optimization, structural characterization and electrocatalytic application.

Unique properties and potential applications of 2D materials draw much attention for mass production of thin-layer 2D materials. Ball milling exfoliation of 2D materials has been rarely used, in spite of a promising dry phase production method, because of the superficial information in the mechanism and the effect of the operating parameters on the yield, size and thickness. Here, we investigate systematically the ball milling operating parameters in the exfoliation of bulk MoS in the presence of sodium cholate (SC) as an exfoliant. The yield and dimensions of the exfoliated MoS nanosheet were monitored by changing the parameters such as the weight ratio of bulk MoS and SC (SC/MoS), the filling ratio in the volume of milling ball and container (φ), milling ball size (d ), milling revolution speed (n ), and initial mass of bulk MoS ([Formula: see text]). The yield of exfoliation is found to be 95% at the optimum ball milling conditions (SC/MoS = 0.75, φ = 50%, [Formula: see text] = 0.20 g). In addition, yield and size of the exfoliated MoS were controlled by the conditions of the ball milling. As for the evaluation of the exfoliated MoS, we developed a novel method by use of the XRD profile to determine the size and thickness of the ball-milled MoS powder with less than 30% difference from those determined by the well-known absorption method. Finally, the size and thickness of the MoS nanosheets prepared by ball milling exfoliation were correlated with their electrocatalytic and photoelectrocatalytic activities.