Proton-induced fast preparation of size-controllable MoS_2 nanocatalyst towards highly efficient water electrolysis

MoS₂ has emerged for catalyzing the hydrogen evolution reaction. Various notable strategies have been developed to downsize the MoS₂ particles and expose more active edges. However, the restacking issue, which reduces the exposure degree, has rarely been taken into account. Herein, we report on a facile proton-induced fast hydrothermal approach to produce size-controllable MoS₂ nanocatalysts and demonstrate that along the varying of sheet sizes, there is a trade-off between the intrinsic catalytic activity (mainly determined by the unsaturated sulfur on the sheet edges) and the active edge accessibility (influenced by the assembly structure). The size-optimized catalyst delivers a high performance of a low overpotential of ～200 mV at 10 mA/cm², a Tafel slope of 46.3 mV/dec, and a stable working state, which is comparable to the recent notable works. Our findings will provide a pathway for its large-scale application and enhance the water electrolysis performance.