Influence of hydrogen-vacancy interactions on H2 dissociative adsorption behavior on austenitic stainless steel surfaces

• Published in: Applied surface science Vol. 713; p. 164258
• Main Authors: Li, Yongshan, Ding, Wenhong, Fu, Yongzhi, Deng, Keke, Chen, Zhuang, Wang, Chengxu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2025
• Subjects: Density functional theory (DFT) calculations; Hydrogen dissociation and adsorption; Vacancy defects; γ-Fe surface; γ-Fe surface; Density functional theory (DFT) calculations; Vacancy defects; Hydrogen dissociation and adsorption
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2025.164258

[Display omitted] •Vacancy-induced electronic coupling enhances H-Fe covalency.Atomic-scale DFT + CI-NEB reveals that vacancy defects on γ-Fe(1 1 1) shorten H-Fe bonds by > 12 % and increase charge localization, driving preferential hydrogen adsorption and crack initiation.•d-band center shift predicts H2 dissociation barriers.Vacancies lower the H2 dissociation barrier by 22.5 % (0.698 eV → 0.525 eV) via synergistic d-orbital hybridization and antibonding state reduction, with charge transfer showing strong correlation (R2 = 0.95) to reactivity.•Thermodynamically stable H-vacancy complexes accelerate degradation.Hydrogen-vacancy coupling reduces defect formation energy by 43.5% while increasing surface energy by 58%, providing atomic-scale insights into hydrogen embrittlement in austenitic steels. The interplay between hydrogen and defects represents a determining factor for hydrogen adsorption/dissociation behavior, permeation rate, and enrichment on metal surfaces, critically influencing material resistance to hydrogen-induced damage. Using density functional theory (DFT), we systematically investigate the electronic-energy coupling effects of Vacancy-defective-1,2,3 on hydrogen adsorption and dissociation mechanisms at γ-Fe(111) surfaces. Results demonstrate that vacancy defects induce Fe-3d orbital energy downshifts and trigger surface charge redistribution, exhibiting a strong negative correlation between charge transfer and dissociation barriers (R2 = 0.95) while creating active adsorption sites. The electronic reconstruction reduces the H2 dissociation barrier to 0.525 eV at Vacancy-defective-1 sites (22.5 % reduction versus pristine surfaces). Concurrently, hydrogen adsorption decreases the vacancy formation energy from 3.763 to 2.125 eV, stabilizing hydrogen-vacancy complexes and promoting preferential H occupation at bridge (BS) and hexagonal close-packed (HCP) sites. Furthermore, we identify subsurface-to-surface vacancy migration accompanied by hydrogen-induced surface energy increases (from 0.126 to 0.406 eV), suggesting possible fracture toughness degradation. This work elucidates the electronic-energy coupling mechanism controlling hydrogen-defect interactions, providing atomic-scale theoretical foundations for designing hydrogen-resistant austenitic steels through defect engineering and surface passivation strategies. The findings offer critical guidance for developing advanced hydrogen storage materials and enhancing material service life in hydrogen environments.