Akademik Veri Yönetim Sistemi
ACS Omega, cilt.11, sa.22, ss.33202-33215, 2026 (SCI-Expanded, Scopus)
Understanding how intrinsic defects govern dopant activity is central to the rational design of catalytic two-dimensional materials. Here, combining first-principles defect thermodynamics with hydrogen adsorption descriptors, we investigate the defect landscape and catalytic behavior of a Cu2S monolayer. Our calculations show that sulfur-on-copper antisites (SCu) are the most thermodynamically favorable intrinsic defects, with defect formation energies ranging from approximately −0.12 to 0.35 eV depending on the chemical potential environment. In contrast, copper vacancies (VCu) exhibit higher defect formation energies in the range of 0.45 to 0.85 eV, but become increasingly stabilized under Cu-poor conditions. Importantly, we demonstrate that thermodynamic stability does not directly correlate with catalytic activity. Although SCu is energetically favored, it shows weak hydrogen binding with a hydrogen adsorption free energy of ΔGH* = −0.66 eV, whereas VCu-based configurations significantly improve hydrogen adsorption toward more optimal values. Single tungsten substitution at Cu sites is found to preferentially stabilize a VCu+W defect complex with a formation energy of approximately 0.28 eV, which modifies the electronic structure by introducing acceptor-like states near the valence band edge while avoiding strongly localized defect levels that may hinder charge transport. This defect-mediated electronic restructuring leads to near-thermoneutral hydrogen adsorption, with ΔGH* improving from −0.66 eV for pristine Cu2S to −0.08 eV for the VCu+W complex. Overall, these results highlight how the interplay between intrinsic defects and extrinsic dopants can be exploited to tune the electronic structure and catalytic behavior of Cu2S, providing general design principles for defect-engineered electrocatalysts for the hydrogen evolution reaction.