We found good reversibility of hydrogen uptake-release in vacancy-centered hexagonal armchair nanographene (VANG) based on density functional theory calculation. VANG has a triply hydrogenated vacancy (V111) at the center and acts as a self-catalytic property to reduce an activation barrier of hydrogen uptake-release. We found remarkable features in an almost equal value of the activation energy barrier of 1.19 eV for hydrogen uptake and 1.25 eV for hydrogen release on V111 of VANG. The dehydrogenation showed slightly exothermic and the hydrogenation became slightly endothermic, suggesting the efficiency of hydrogen uptake-release. In high hydrogen coverage, the quintuply hydrogenated vacancy (V221) is formed with some hydrogenated located in the in-plane and armchair edges. This structure produces an exothermic hydrogen release from the in-plane with an energy barrier of not more than 2 eV. This finding potentially addresses the low reversibility issues in the organic chemical hydrides as hydrogen storage materials.
@article{arxiv.2206.15060,
title = {Discovery of nanographene for hydrogen storage solving low reversibility issues},
author = {Gagus Ketut Sunnardianto and Yusuf Wicaksono and Halimah Harfah and Koichi Kusakabe},
journal= {arXiv preprint arXiv:2206.15060},
year = {2022}
}