Metal-decorated HOP-graphene as a promising media for high-capacity reversible hydrogen storage: Insights from DFT and AIMD simulations

Abstract

Two-dimensional (2D) materials have been extensively investigated for applications in gas sensing, catalysis, and energy storage, owing to their exceptional surface area and high structural tunability. In the context of addressing global warming and transitioning to cleaner energy alternatives, hydrogen-based energy systems have emerged as promising solutions. However, efficient hydrogen storage and release require the development of suitable substrate materials. In this study, we perform a comprehensive density functional theory (DFT) investigation of Li- and Na-decorated HOP-graphene, a 2D carbon allotrope characterized by its unique 5-6-8 ring configuration, as a candidate for hydrogen (H 2 ) storage. Our calculations reveal a remarkable hydrogen uptake capacity of 10.74 wt% and 8.85 wt% for Li and Na decoration, respectively, with both systems capable of accommodating up to 32 H 2 molecules. Moreover, the predicted desorption temperatures are close to room temperature, attributed to the presence of Kubas-type interactions. Ab initio molecular dynamics (AIMD) simulations further support this behavior, demonstrating substantial hydrogen release at 300 K without any structural degradation of the decorated substrate. These results position metal-decorated HOP-graphene as a highly promising and efficient material for next-generation hydrogen storage applications.