Field-Effect Tuned Adsorption Dynamics of VSe 2 Nanosheets for Enhanced Hydrogen Evolution Reaction.

Transition metal dichalcogenides, such as MoS2 and VSe2 have emerged as promising catalysts for the hydrogen evolution reaction (HER). Substantial work has been devoted to optimizing the catalytic performance by constructing materials with specific phases and morphologies. However, the optimization of adsorption/desorption process in HER is rare. Herein, we concentrate on tuning the dynamics of the adsorption process in HER by applying a back gate voltage to the pristine VSe2 nanosheet. The back gate voltage induces the redistribution of the ions at the electrolyte-VSe2 nanosheet interface, which realizes the enhanced electron transport process and facilitates the rate-limiting step (discharge process) under HER conditions. A considerable low onset overpotential of 70 mV is achieved in VSe2 nanosheets without any chemical treatment. Such unexpected improvement is attributed to the field tuned adsorption-dynamics of VSe2 nanosheet, which is demonstrated by the greatly optimized charge transfer resistance (from 1.03 to 0.15 MΩ) and time constant of the adsorption process (from 2.5 × 10-3 to 5.0 × 10-4 s). Our results demonstrate enhanced catalysis performance in the VSe2 nanosheet by tuning the adsorption dynamics with a back gate, which provides new directions for improving the catalytic activity of non-noble materials.