Vertically mounting molybdenum disulfide nanosheets on dimolybdenum carbide nanomeshes enables efficient hydrogen evolution
Tingting Wang, Pengyan Wang, Yajun Pang, Yitian Wu, Jin Yang, Hao Chen, Xiaorui Gao, Shichun Mu, Zongkui Kou
Abstract
Designing hierarchical heterostructure to optimize the adsorption of hydrogen intermediate (H*) is impressive for hydrogen evolution reaction (HER) catalysis. Herein, we show that vertically mounting two-dimensional (2D) layered molybdenum disulfide (MoS2) nanosheets on 2D nonlayered dimolybdenum carbide (Mo2C) nanomeshes to form a hierarchical heterostructure largely accelerates the HER kinetics in acidic electrolyte due to the weakening adsorption strength of H* on 2D Mo2C nanomeshes. Our hierarchical MoS2/Mo2C heterostructure therefore gives a decrease of overpotential for up to 500 mV at −10 mA·cm−2 and an almost 200-fold higher kinetics current density compared with the pristine Mo2C nanomeshes and maintains robust stability with a small drop of overpotential for only 16 mV upon 5,000 cycles. We further rationalize this finding by theoretical calculations and find an optimized adsorption free energy of H*, identifying that the MoS2 featuring strong H* desorption plays a key role in weakening the strong binding of Mo2C with H* and therefore improves the intrinsic HER activity on active C sites of Mo2C. This present finding shines the light on the rational design of heterostructured catalysts with synergistic geometry.