Hydrogen storage in carbon-based yne-diamond superstructures

Abstract

Among the materials considered for hydrogen storage via physical adsorption, framework-type carbon allotropes stand out due to their porosity, as well as their resistance to heat and moisture. In this study, yne-diamond carbon frameworks were constructed by inserting linear sp-hybridized carbon units between the sp3-hybridized carbon atoms of a diamond-like lattice, thereby generating a series of progressively more porous structures. Their structural, electronic, mechanical, porosity, and hydrogen adsorption properties were evaluated using geometry optimization, density functional theory, pore-network analysis, and Grand Canonical Monte Carlo simulations. The yne-Z2 and yne-Z3 structures, identified as suitable for hydrogen storage, were calculated to exhibit hydrogen storage capacities of 6.46 and 11.97 wt.% at 77 K and 1 bar, respectively. Compared to conventional adsorbent materials, these structures demonstrate remarkably high performance and are considered a mechanically strong alternative for hydrogen storage. In particular, detailed investigation of their performance limits and hydrogen storage characteristics identifies yne-Z2 and yne-Z3 as computationally promising structures for hydrogen storage applications.