Abstract: Two-dimensional (2D) transition metal dichalcogenides (TMDs) are promising electrocatalysts for hydrogen evolution reaction (HER). They can replace Pt-based electrocatalyst in HER due to the optimal hydrogen adsorption Gibbs free energy (∆GH*) at active sites and high chemical stability. However, their real-time HER performance remains poor due to largely inactive basal-plane and poor electrical conductivity.

In this talk, I will show how we effectively activated the inert basal plane and induce metallic properties into 2H-molybdenum disulfide (MoS2) via in-situ vanadium atom substitution to form vanadium sulfide (VSn) single-atom catalyst (SAC) unit in the MoS2 lattice (V-MoS2). We demonstrated that electrode engineering can tune the ∆GH* of active sites to trigger more basal plane activity to Pt-scalable HER performance. The V-MoS2 electrocatalyst generates ~1,000 mA cm-2 current density at 0.6 V, recorded an overpotential of -0.08 V at a current density of 10 mA, and 0.2 Ω charge transfer resistance, indicating the much-improved catalytic activity of the V-MoS2. This study adds new fundamental insight into ways we can engineer 2D TMDs at the atomic level for applications such as electrocatalyst and other electrochemical devices.