Hydrogen trapping in vanadium carbide alloyed with transition metals

• Published in: Nuclear materials and energy Vol. 36; p. 101504
• Main Authors: Tang, Shuai, Li, Linxian, Yan, Haile, Jin, Jianfeng, Peng, Qing, Cai, Minghui, Li, Jianping, Liu, Zhenyu, Wang, Guodong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2023; Elsevier
• Subjects: First-principles calculations; Hydrogen barrier coating; Transition-metal alloying; Vanadium carbide; First-principles calculations; Vanadium carbide; Hydrogen barrier coating; Transition-metal alloying
• ISSN: 2352-1791; 2352-1791
• DOI: 10.1016/j.nme.2023.101504

•The maximum number of H atoms that can be trapped is 6 in doped by Cr, compared to 4 doped by Ti, Zr, Nb, and Mo.•Less lattice contraction distortion and the lower loss of charge transfer make the Cr has distinguished performance on the hydrogen trapping.•The key factor for the maximum stable hydrogen number is the length and strength of the C-H bond in the doped VC. The mechanism of hydrogen trapping in carbides via transition metal alloying is essential for material design of hydrogen barrier coatings in hydrogen energy applications, which however, is still elusive. Herein we have investigated the effect of transition metal solutes (Ti, Cr, Zr, Nb, and Mo) doping on multiple hydrogen trapping in vanadium carbide using density functional theory calculations. The hydrogen binding energetics with alloying elements depends on the local atomic environment of neighboring interstitial sites. The hydrogen trapping ability is ordered by Cr > Zr > Nb > Ti > Mo. Cr dopant has a distinctive performance, because its first-nearest-neighbor trigonal interstitial sites are more stable, and up to six hydrogen atoms can be trapped, surpassing other elements. This distinction is partially attributed to less lattice contractive distortion and lower loss of charge. Charge transfer and electronic analysis indicate that CH interactions play a critical role in hydrogen binding energies. The stability of multiple hydrogen could be measured by the length and strength of the CH bond.