Hydrogen Storage Mechanism by Gas-Phase Vanadium Cluster Cations Revealed by Thermal Desorption Spectrometry

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2023-10, Vol.127 (42), p.8821-8827
• Main Authors: Wu, Yangkun, Miyajima, Ken, Kudoh, Satoshi, Nagata, Toshiaki, Mafuné, Fumitaka
• Format: Article
• Language: English
• Subjects: A: Structure, Spectroscopy, and Reactivity of Molecules and Clusters
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/acs.jpca.3c04457

The adsorption of hydrogen on gas-phase vanadium cluster cations, V n + (n = 3–14), at 300 K and desorption of hydrogen from hydride clusters, V n H m +, upon heating were observed experimentally by combined thermal desorption spectrometry and mass spectrometry analyses. The ratio m/n was approximately 1.3 for all n values at 300 K, which was reduced to approximately zero at 1000 K. For n = 4, stable cluster geometries of V4H m + (m = 0, 2, 4, and 6) were investigated by DFT calculations, revealing that V4 adopted a trigonal pyramidal structure and the H atoms adsorbed mainly on the μ2 bridge sites. The adsorption reaction pathway of one H2 molecule on V4 + was also investigated. The experimentally estimated desorption energies of the H2 molecules were consistent with their calculated binding energies. Among the observed hydride clusters, V6H8 + was found to be significantly thermally durable, probably because of its close-packed octahedral V6 core structure, with H atoms occupying all hollow sites.