preprints.org > physical sciences > condensed matter physics > doi: 10.20944/preprints202409.2279.v1 (registering DOI)

Preprint Article Version 1 This version is not peer-reviewed

Version 1 : Received: 26 September 2024 / Approved: 27 September 2024 / Online: 30 September 2024 (11:03:36 CEST)

We perform first-principles Molecular Dynamics calculations to test the total attraction forces on a physisorbed molecule at a given temperature and ambient pressure and apply it to the hydrogen storage on the 2D material MoP2. We considered the pristine material and one with 12.5% of Mo vacancies. By optimization, we calculated a gravimetric capacity for pristine MoP2 of 5.72%, with an adsorption energy of ‒ 0.13 eV/molecule. We found 6.02% and ‒ 0.14 eV/molecule for the second case. Next, we apply our approach to know if the molecular hydrogen physisorption obtained by simple energy optimization exists for a given temperature and ambient pressure. We used this approach to determine the number of molecules adsorbed on the surface at a given temperature. Thus, we conducted a first-principles molecular dynamics (FPMD) calculation at temperature T1, using optimization as the initial system configuration. Subsequently, we performed a second FPMD calculation at a temperature T2 (with T2 ‹‹ T1), using the stable configuration of the first FPMD calculation as the initial configuration. We identified as adsorbed molecules at temperature T1, only those forced back toward the surface at temperature T2 due to kinetic energy loss at the lower temperature T2. The defective surface gave the best gravimetric capacity, ranging from 5.27% at 300 K to 6.02% at 77 K. The latter met the requirement from the US-DOE, indicating the potential practical application of our research in hydrogen storage.

2D materials; 2D MoP2; Surface forces; Adsorption

Physical Sciences, Condensed Matter Physics

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