First-principles insights into hydrogen trapping in interstitial-vacancy complexes in vanadium carbide

• Published in: Physical chemistry chemical physics : PCCP 2022-08, Vol.24 (34), p.24-248
• Main Authors: Tang, Shuai, Li, Lin-xian, Peng, Qing, Yan, Hai-le, Cai, Ming-hui, Li, Jian-ping, Liu, Zhen-yu, Wang, Guo-dong
• Format: Article
• Language: English
• Subjects: Carbon; Charge density; Electronic structure; Energy of solution; First principles; Free energy; Heat of solution; Hydrogen bonds; Structural analysis; Trapping; Vacancies; Vanadium base alloys; Vanadium carbide
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d2cp02425j

Hydrogen trapping is a key factor in designing advanced vanadium alloys and steels, where the influence of carbon vacancies is still elusive. Herein we have investigated the effect of carbon vacancies on the hydrogen trapping of defect-complexes in vanadium carbide using first-principles calculations. When a carbon vacancy is present, the second nearest neighboring trigonal interstitial is a stable hydrogen trapping site. A C vacancy enhances the hydrogen trapping ability by reducing the chemical and mechanical effects on H atom solution energy. Electronic structure analysis shows that C vacancies increase the charge density and the Bader atomic volume, leading to a lower H atom solution energy. The strength of the V-H bond is predominant in determining the hydrogen trapping ability in the presence of a C vacancy, in contrast to that of a C-H bond when the C vacancy is absent. Hydrogen trapping is a key factor in designing advanced vanadium alloys and steels, where the influence of carbon vacancies is still elusive.