Strain-Mediated Electronic Structure Reconstruction of Frenkel Defects in Monolayer MoSe2: A First-Principles Study

Abstract

Using first-principles DFT, we investigate the synergistic modulation of the electronic structure of monolayer MoSe₂ by biaxial strain and Frenkel defects for electrocatalytic hydrogen evolution. A biaxial compressive strain of −4% lowers the Frenkel defect formation energy from 2.41 eV to 1.85 eV. The defect-strain synergy introduces in-gap states, increases the density of states at the Fermi level, modulates the Mo d-band center, strengthens orbital hybridization, and optimizes surface charge distribution and work function. Consequently, the hydrogen adsorption free energy (ΔG_H*) changes from 1.92 eV on the pristine basal plane to −0.01 eV, approaching the ideal thermodynamic value. Detailed analysis of the correlation between the d-band center and ΔG_H* elucidates the microscopic origin of this optimization. Phonon dispersion and AIMD simulations confirm dynamical stability at room temperature. This work reveals the microscopic mechanism of strain–defect coupling in enhancing catalytic activity and provides a physical basis for the rational design of two-dimensional transition metal dichalcogenide electrocatalysts for clean energy applications.