Large-scale preparation of 2D VSe2 through a defect-engineering approach for efficient hydrogen evolution reaction

Abstract

Transition-metal dichalcogenides (TMDs), such as VSe2, are widely explored as promising hydrogen evolution reaction (HER) electrocatalysts, however, the catalytically inert basal planes remain a great challenge limiting the H2 evolution process. Herein, a defect-engineering approach is adopted to activate the inert basal planes of VSe2 by embedding Se vacancies in the crystal lattice via the sealed-quartz tube technology at controlled reaction conditions. The Se vacancies are introduced by tuning the molar ratio of V and Se powders which in situ forms V3+ to revamp the electronic configuration and expose more catalytic active sites favoring reduce the Gibbs free energy of hydrogen adsorption (△GH). The upgraded VSe2-1.8 delivers an overpotential value of 160 mV at a current density of 10 mA cm−2 which shows its superiority compared with the reported literatures. Not only that, a small Tafel slope 85 mV dec-1 and excellent stability for 48 h demonstrate its fast reaction kinetics and applicability for a long period of time. Moreover, the theoretical calculation results also indicate that introducing proper Se-vacancy density to form the separate defects on the basal plane of VSe2 can yield the optimal △GH, which achieve higher intrinsic HER activity. Furthermore, a high throughput synthesis device is designed for large-scale preparation of the catalysts which is much suitable for application at commercial level. The defect engineering technique to trigger more active sites provides a novel and efficient way to enhance HER performance of 2D TMDs.