Finite-Temperature Hydrogen Adsorption/Desorption Thermodynamics Driven by Soft Vibration Modes

Journal Article · Tue Jan 01 00:00:00 EST 2013 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.111.066102· OSTI ID:1093731

Woo, Sung-Jae ^[1]; Lee, Eui-Sup ^[1]; Yoon, Mina ^[2]; Yong-Hyun, Kim ^[1]

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1. KAIST, Daejeon, Republic of Korea
2. ORNL

It is widely accepted that room-temperature hydrogen storage on nanostructured or porous materials requires enhanced dihydrogen adsorption. In this work we reveal that room-temperature hydrogen storage is possible not only by the enhanced adsorption, but also by making use of the vibrational free energy from soft vibration modes. These modes exist for example in the case of metallo-porphyrin-incorporated graphenes (M-PIGs) with out-of-plane ( buckled ) metal centers. There, the in-plane potential surfaces are flat because of multiple-orbital-coupling between hydrogen molecules and the buckled-metal centers. This study investigates the finite-temperature adsorption/desorption thermodynamics of hydrogen molecules adsorbed on M-PIGs by employing first-principles total energy and vibrational spectrum calculations. Our results suggest that the current design strategy for room-temperature hydrogen storage materials should be modified by explicitly taking finite-temperature vibration thermodynamics into account.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1093731
• Journal Information: Physical Review Letters, Vol. 111, Issue 6; ISSN 0031--9007
• Country of Publication: United States
• Language: English