In:
Journal of Materials Chemistry A, Royal Society of Chemistry (RSC), Vol. 10, No. 37 ( 2022), p. 19839-19851
Abstract:
Magnesium hydride (MgH 2 ) is considered as a promising solid-state hydrogen storage material due to its high hydrogen storage mass density and environmental friendliness. However, its sluggish dehydrogenation kinetics are still the bottleneck that restricts practical applications. To address this challenge, very recent pioneering experiments found that MgH 2 /single-atom catalyst (MgH 2 /SAC) heterojunctions can be promising candidates for hydrogen storage. However, the reaction mechanism and design guideline were still not well understood. Herein, we design and analyze MgH 2 /SAC heterojunction systems including nine 3d transition metals, using spin-polarized density functional theory calculations with van der Waals corrections. We found that the energy barriers of MgH 2 dehydrogenation are significantly reduced by 0.51–2.22 eV through the promotion effects of a heterojunction. Using ab initio molecular dynamics simulations, these promotion effects were analyzed in depth based on the observation of hydrogen diffusion behaviors. To provide further insights, the electron localization function, charge density difference, hydrogen adsorption energy, system electronegativity, d-band center, and crystal orbital Hamilton population were comprehensively analyzed to understand the origin of the high performance of MgH 2 /SACs. In particular, we found that the system electronegativity of SACs can act as an effective descriptor that predicts the dehydrogenation energy barriers. Most importantly, this study provides important design guidelines of a brand-new type of MgH 2 /SAC material and a promising solution to the sluggish kinetics of MgH 2 dehydrogenation in hydrogen storage.
Type of Medium:
Online Resource
ISSN:
2050-7488
,
2050-7496
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
2702232-8
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