Effect of Li Adsorption on the Electronic and Hydrogen Storage Properties of Acenes: A Dispersion-Corrected TAO-DFT Study

TL;DR

This study uses dispersion-corrected TAO-DFT to accurately predict the electronic and hydrogen storage properties of Li-adsorbed acenes, showing they meet USDOE targets for hydrogen storage capacity.

Contribution

It demonstrates the effectiveness of TAO-DFT with dispersion corrections in modeling complex systems with strong static correlation effects.

Findings

H2 binding energies are in the ideal range (20-40 kJ/mol)

Hydrogen storage capacities reach 9.9-10.7 wt%, surpassing USDOE targets

Li-adsorbed acenes are promising for reversible hydrogen storage at ambient conditions

Abstract

Due to the presence of strong static correlation effects and noncovalent interactions, accurate prediction of the electronic and hydrogen storage properties of Li-adsorbed acenes with n linearly fused benzene rings (n = 3 - 8) has been very challenging for conventional electronic structure methods. To meet the challenge, we study these properties using our recently developed thermally-assisted-occupation density functional theory (TAO-DFT) with dispersion corrections. In contrast to pure acenes, the binding energies of H2 molecules on Li-adsorbed acenes are in the ideal binding energy range (about 20 to 40 kJ/mol per H2). Besides, the H2 gravimetric storage capacities of Li-adsorbed acenes are in the range of 9.9 to 10.7 wt%, satisfying the United States Department of Energy (USDOE) ultimate target of 7.5 wt%. On the basis of our results, Li-adsorbed acenes can be high-capacity hydrogen storage materials for reversible hydrogen uptake and release at ambient conditions.