Wrinkle facilitated hydrogen evolution reaction of vacancy-defected transition metal dichalcogenide monolayers

Utilizing transition metal dichalcogenides (TMDs) as catalysts in the hydrogen evolution reaction (HER) is a promising prospect for hydrogen production. Here, by first-principles calculations we reveal that the catalytic activities of vacancy-defected TMD MX₂ (M = Mo or W and X = S, Se or Te) monolayers for the HER can be significantly improved by wrinkle engineering. The hydrogen adsorption Gibbs free energies of defected TMDs decrease with decreasing wrinkle length. By appropriately controlling and adjusting the wrinkle size and vacancy number, the hydrogen adsorption Gibbs free energy will be close to zero, allowing the wrinkled TMDs to reach their optimum catalytic capability. The improvement of the catalytic activity of TMDs is mainly attributed to the charge transfer and polarization enhancement of metal atoms at the vacancy sites, which are caused by the coupling effect of vacancy defects and wrinkling deformation induced flexoelectricity. These results provide an attractive route for the application of TMDs in hydrogen production by combining wrinkle engineering and defect engineering.