Electric Field Enhanced Hydrogen Storage on BN Sheet

TL;DR

This study demonstrates through density functional theory that applying an electric field significantly enhances hydrogen storage capacity on BN sheets by increasing adsorption energies and enabling reversible storage, meeting DOE targets.

Contribution

The paper introduces a method of using electric fields to improve hydrogen storage on BN sheets, showing increased binding energies and reversibility, which was not previously demonstrated.

Findings

Adsorption energy of H2 increases from 0.07 eV to 0.48 eV with electric field.

Gravimetric density reaches 7.5 wt %, meeting DOE targets.

Hydrogen can be released easily once electric field is removed.

Abstract

Using density functional theory we show that an applied electric field substantially improves the hydrogen storage properties of a BN sheet by polarizing the hydrogen molecules as well as the substrate. The adsorption energy of a single H2 molecule in the presence of an electric field of 0.05 a.u. is 0.48 eV compared to 0.07 eV in its absence. When one layer of H2 molecules is adsorbed, the binding energy per H2 molecule increases from 0.03 eV in the field-free case to 0.14 eV/H2 in the presence of an electric field of 0.045 a.u. The corresponding gravimetric density of 7.5 wt % is consistent with the 6 wt % system target set by DOE for 2010. Once the applied electric field is removed, the stored H2 molecules can be easily released, thus making the storage reversible.