Isomers of C12N12 as potential hydrogen storage materials and the effect of the electric field therein

Abstract

The relative stability, aromaticity and hydrogen storage ability of different C₁₂N₁₂ isomers are computationally assessed at B3LYP/6-31G(d), DFT-D-B3LYP/6-31G(d) and M052X/6-311+G(d,p) levels of theory. A negative nucleus independent chemical shift at the cage center [NICS(0)] and a high value for the gas phase heat of formation justify the stability as well as efficacy of these C₁₂N₁₂ isomers as promising high-energy density materials (HEDMs). Each nitrogen site is found to adsorb one hydrogen molecule which corresponds to a gravimetric density of 7.2 wt%. The temperature–pressure plot of the Gibbs free energy change separates the thermodynamically spontaneous regions of the hydrogen adsorption and desorption processes. The application of an external electric field increases the binding energy of hydrogen adsorption by ∼0.50 kcal mol⁻¹. One of the C₁₂N₁₂ isomers is the basic building block involved in the formation of two different kinds of one-dimensional cluster assembled materials.