Mechanical Reversal in the Catalytic Capability of Monolayer Transition Metal Dichalcogenides for Hydrogen Evolution Reaction: An Explicit First-Principles Study

Pristine transition metal dichalcogenide (TMD) monolayers are generally regarded as exhibiting low chemical reactivity due to their inert surfaces. Our extensive first-principles calculations, which incorporate an explicit solvation model, reveal that the catalytic performance of pristine TMD MX₂ (where M = Mo or W, and X = S, Se or Te) monolayers for hydrogen evolution reaction can be significantly altered and enhanced through mechanically bending deformation. For a WTe₂ monolayer, its hydrogen adsorption Gibbs free energy decreases to 0.004 eV under a bending curvature of 0.15 Å^-1. The notable reversal in the catalytic capability of curved TMD monolayers can be primarily ascribed to the interplay between elastic energy stimuli and hydrogen adsorption energy barrier, alongside charge transfer to metal atoms facilitated by the weakening of M-X bonds and the exposure of metal atoms. A theoretical model has been established to elucidate the relationship among hydrogen adsorption Gibbs free energy, bending elastic energy, and adsorption energy barrier.