Size-dependent and support-enhanced electrocatalysis of 2H-MoS2 for hydrogen evolution

Both theoretical and experimental investigations have shown that two-dimensional (2D) materials present intriguing electrocatalytic activity due to their unique layered structures and fascinating electronic properties. The exploitation of 2D electrocatalysts towards the hydrogen evolution reaction (HER) is highly required. Herein, we report an all-physical top-down method to produce trigonal (2H) phase molybdenum disulfide nanosheets (2H-MoS2 NSs) with full-scale (161–2 nm) controlled sizes. The influence of the sizes on HER is systematically investigated, and the underlying mechanism is proposed. The reduction in NS sizes enables linear improvement of their HER performances. Benefiting from the synergistic effect between quantum sheets (QSs) and NSs, the QS/NS heterostructures exhibit further enhanced HER activity with highly desired long-term durability. Extremely low values, such as an overpotential of 179 mV (at 10 mA cm−2), a Tafel slope of 82 mV dec−1, and a charge transfer resistance value of 19 Ω, are derived for the MoS2 QSs/Ti3C2 NSs in acidic media, which is comprehensively superior to most of the reported MoS2-based catalysts. This work shows the great potential of 2D QSs as efficient electrocatalysts and provides new insights on the rational design of QS/NS heterostructures.