Influence of Pt decoration on the hydrogen storage performance of cup-stacked carbon nanotubes: A DFT study

Abstract

The hydrogen adsorption behaviour of cup-stacked carbon nanotubes (CSCNTs) decorated with the platinum atom at four positions of the conical graphene layer (CGL) is investigated using density functional theory. The optimization shows that the inside lower edge position (IL) results have the best hydrogen adsorption parameters among the four positions. The Pt–H2 distance is 1.54 Å, the H–H bond length (lH-H) is 1.942 Å, and the hydrogen adsorption energy (Eads) is 1.51 eV. The hydrogen adsorption of CSCNTs decorated by Pt at the IL position also has larger Eads and lH-H than the Pt-doped planar graphene, Pt-doped single-wall carbon nanotubes and Pt-doped carbon nanocones. The Pt atom at the IL position has a more significant polarization effect on the adsorbed H2, it has trends to convert H2 into two separate H atoms. While the hydrogen adsorption behaviour at other positions belongs to the Kubas coordination, the lH-H and the Eads increased not significantly.