Hydrogen adsorption on Ce/BNNT systems: A DFT study

The adsorption of H2 on Ce-doped boron nitride nanotubes (BNNT) is investigated by using density functional theory. For the Ce/BNNT system, it is found that Ce preferentially occupies the hollow site over the BN hexagon. The results indicate that seven H2 per Ce can be adsorbed and 5.68 wt% H2 can be stored in Ce3/BNNT system. Among nanotubes doped with metals, Ce exhibits the most favorable hydrogen adsorption characteristics in terms of the adsorption energy and the uptake capacity. Both hybridization of the Ce-5d orbital with the H-1s orbital and the polarization of the H2 molecules contribute to the hydrogen adsorption. Ce clustering can be suppressed by preferential binding of Ce atoms on BNNT, which denotes that BNNT as a hydrogen storage substrate is better than CNT due to its heteropolar binding nature.

Graphical abstractCe/BNNT system is a good candidate for hydrogen storage where seven H2 per Ce can be adsorbed.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ce/BNNT system as a good candidate for hydrogen storage can adsorb seven H2 per Ce. ► BNNT as a hydrogen storage substrate is better than CNT. ► Metal clustering can be suppressed by preferential binding of metal atoms on BNNT. ► H2 adsorption is due to the electronic hybridization and electrostatic interactions.