Sodium-Decorated Ennea-Graphene: A Novel 2D Carbon Allotrope for High-Capacity Hydrogen Storage

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Hauptverfasser: Huacarpuma, Bill D. Aparicio, Laranjeira, José A. S., Martins, Nicolas F., Sambrano, Julio R., de Mendonça, Fábio L. Lopes, Dias, Alexandre C., Junior, Luiz A. Ribeiro
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Veröffentlicht: 2025
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author Huacarpuma, Bill D. Aparicio
Laranjeira, José A. S.
Martins, Nicolas F.
Sambrano, Julio R.
de Mendonça, Fábio L. Lopes
Dias, Alexandre C.
Junior, Luiz A. Ribeiro
author_facet Huacarpuma, Bill D. Aparicio
Laranjeira, José A. S.
Martins, Nicolas F.
Sambrano, Julio R.
de Mendonça, Fábio L. Lopes
Dias, Alexandre C.
Junior, Luiz A. Ribeiro
contents The development of safe, efficient, and reversible hydrogen storage materials is critical for advancing hydrogen-based energy technologies and achieving carbon-neutral goals. Ennea-Graphene, a new 2D carbon allotrope made of 4-, 5-, 6-, and mainly 9-membered carbon rings (nonagons), is introduced via Density Functional Theory (DFT) calculations. Phonon dispersion and ab initio molecular dynamics demonstrate that the monolayer is mechanically and dynamically stable at 300 K, as no imaginary modes are detected. The pristine system further exhibits metallic-like electronic behavior. The material exhibits high in-plane stiffness (Young modulus of 255 N/m). Sodium adsorption at the centers of the nonagonal rings is energetically favorable, with a binding energy of approximately -1.56 eV, leading to the formation of the Na@Ennea-Graphene complex. The calculated H2 adsorption energies range from -0.15 eV to -0.18 eV. The Na-decorated structure demonstrates excellent hydrogen storage performance, reversibly adsorbing up to four H2 molecules per Na atom (8.8 wt\% H2). This capacity surpasses the U.S. Department of Energy's 2025 target for onboard hydrogen storage materials. The adsorbed H2 remains molecular (H-H bond of 0.76~Å) and can be released under near-ambient conditions, as verified by 300 K ab initio molecular dynamics simulations. These findings position sodium-decorated Ennea-Graphene as a promising nanomaterial for next-generation hydrogen storage technologies.
format Preprint
id arxiv_https___arxiv_org_abs_2509_19060
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Sodium-Decorated Ennea-Graphene: A Novel 2D Carbon Allotrope for High-Capacity Hydrogen Storage
Huacarpuma, Bill D. Aparicio
Laranjeira, José A. S.
Martins, Nicolas F.
Sambrano, Julio R.
de Mendonça, Fábio L. Lopes
Dias, Alexandre C.
Junior, Luiz A. Ribeiro
Applied Physics
Materials Science
The development of safe, efficient, and reversible hydrogen storage materials is critical for advancing hydrogen-based energy technologies and achieving carbon-neutral goals. Ennea-Graphene, a new 2D carbon allotrope made of 4-, 5-, 6-, and mainly 9-membered carbon rings (nonagons), is introduced via Density Functional Theory (DFT) calculations. Phonon dispersion and ab initio molecular dynamics demonstrate that the monolayer is mechanically and dynamically stable at 300 K, as no imaginary modes are detected. The pristine system further exhibits metallic-like electronic behavior. The material exhibits high in-plane stiffness (Young modulus of 255 N/m). Sodium adsorption at the centers of the nonagonal rings is energetically favorable, with a binding energy of approximately -1.56 eV, leading to the formation of the Na@Ennea-Graphene complex. The calculated H2 adsorption energies range from -0.15 eV to -0.18 eV. The Na-decorated structure demonstrates excellent hydrogen storage performance, reversibly adsorbing up to four H2 molecules per Na atom (8.8 wt\% H2). This capacity surpasses the U.S. Department of Energy's 2025 target for onboard hydrogen storage materials. The adsorbed H2 remains molecular (H-H bond of 0.76~Å) and can be released under near-ambient conditions, as verified by 300 K ab initio molecular dynamics simulations. These findings position sodium-decorated Ennea-Graphene as a promising nanomaterial for next-generation hydrogen storage technologies.
title Sodium-Decorated Ennea-Graphene: A Novel 2D Carbon Allotrope for High-Capacity Hydrogen Storage
topic Applied Physics
Materials Science
url https://arxiv.org/abs/2509.19060