Modification of graphenylene nanostructure with transition metals (Fe, Sc and Ti) to promote hydrogen storage ability: A DFT-D3 study

Hydrogen, as a clean alternative to fossil fuels, has received much attention in recent years. But its utilizing requires to overcome storage problems. Here, we investigated the hydrogen adsorption behavior of graphenylene (GPY), a 2D carbon nanostructure, and Sc, Fe and Ti transition metal (TM) decorated GPY by spin-polarized DFT calculations. For TM-decoration of GPY, seven different sites and various distances from carbon sheet were investigated, carefully. Structural and electronic properties of the structures, adsorption energies, band gap values, and the most stable configurations were considered and discussed. Results showed that 6-membered ring (H2 site) is the best site for Sc, Fe, and Ti-decoration and corresponding E-ads was-3.95,-2.66, and-3.65 eV, respectively. Also, pristine GPY and Sc and Ti-decorated GPY have not magnetic character, unlike Fe-GPY. As well, entrance of Sc, Fe and Ti atoms in H2 site of the GPY structure causes its band gap increases from 0.033 eV to of 0.491, 0.080, and 0.372 eV, respectively. E-ads of the H-2 molecule onto pristine GPY is low (-0.160 eV), and must be improved for practical hydrogen storage applications. Sc, Fe, and Ti-decoration improves it about 2.23, 5.69 and 3.63 times. Because of this improvement, we could store up to 20H(2) molecules on TM-decorated GPY systems. These results indicate that TM-decorated GPY can be a suitable option for H-2 storage applications in the future. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Hydrogen gas adsorption behaviors of graphenylene (GPY) and GPY decorated with transition metals (TM) Sc, Fe, and Ti were investigated using spin-polarized DFT calculations. The most stable configuration for TM-decoration was found to be the 6-membered ring (H2 site), with corresponding adsorption energies of -3.95 eV for Sc, -2.66 eV for Fe, and -3.65 eV for Ti. The band gap of GPY structure increased significantly with the entrance of Sc, Fe, and Ti atoms in H2 site, making it a promising option for hydrogen storage applications in the future.