Mild Liquid-Phase Exfoliation of Transition Metal Dichalcogenide Nanosheets for Hydrogen Evolution

Developing a general strategy to efficiently exfoliate transition metal dichalcogenide (TMD) electrocatalysts would be significantly beneficial for the electrocatalytic hydrogen evolution reaction (HER) from water splitting. However, there are several challenges in the production of two-dimensional (2D) TMDs, including the complicated fabrication process, high defect rate, and low production yield. Herein, we developed a general applicable mild organic molecular intercalator-assisted liquid-phase exfoliation method to produce TMD nanosheets in a large scale. The as-prepared ultrathin WSe2, MoSe2, WS2, and MoS2 nanosheets have a 2D nanosheet structure with a thickness of ∼3 nm and lateral size in a few hundred nanometers. This mild intercalation method can avoid introducing harsh exfoliation conditions used in conventional liquid-phase exfoliation, electrochemistry exfoliation, and lithium intercalation, thus resulting in high-quality exfoliation of TMD crystals. Additionally, benefiting from superior intrinsic electrical conductivity, unique 2D structure, and highly exposed active sites, the exfoliated WSe2 and MoSe2 nanosheets exhibited excellent catalytic activity for HER in acid with overpotentials of 223 and 225 mV at a current density of 10 mA cm–2 and low Tafel slopes of 64 and 65 mV dec–1, respectively.