Electronic and Hydrogen Storage Properties of Li-Terminated Linear Boron Chains Studied by TAO-DFT

Abstract

Abstract It has been extremely difficult for conventional computational approaches to reliably predict the properties of multi-reference systems (i.e., systems possessing radical character) at the nanoscale. To resolve this, we employ thermally-assisted-occupation density functional theory (TAO-DFT) to predict the electronic and hydrogen storage properties of Li-terminated linear boron chains (Li2B n ), with n boron atoms (n = 6, 8, …, and 16). From our TAO-DFT results, Li2B n , which possess radical character, can bind up to 4 H2 molecules per Li, with the binding energies in the desirable regime (between 20 and 40 kJ/mol per H2). The hydrogen gravimetric storage capacities of Li2B n range from 7.9 to 17.0 wt%, achieving the ultimate goal of the United States Department of Energy. Accordingly, Li2B n could be promising media for storing and releasing H2 at temperatures much higher than the boiling point of liquid nitrogen.