TPHE-Graphene: A First-Principles Study of a New 2D Carbon Allotrope for Hydrogen Storage

TL;DR

This study introduces sodium-decorated TPHE-graphene, a stable 2D carbon material with high hydrogen storage capacity and suitable adsorption energies, promising for sustainable energy solutions.

Contribution

It is the first first-principles investigation of TPHE-graphene's potential for hydrogen storage, demonstrating its stability and high capacity when decorated with sodium.

Findings

Stable TPHE-graphene exhibits metallic behavior and high Young's modulus.

Na decoration leads to strong chemisorption with minimal clustering.

Each Na atom can adsorb up to five H₂ molecules, achieving 9.52 wt% storage capacity.

Abstract

The shift from fossil fuels to renewable energy sources is essential for reducing global carbon emissions and addressing climate change. Developing advanced materials for efficient hydrogen storage enables sustainable energy solutions in this context. Herein, we propose sodium-decorated TPHE-graphene as a high-performance two-dimensional material for hydrogen storage. Density functional theory (DFT) calculations demonstrate that TPHE-graphene exhibits dynamical, thermal, energetic, and mechanical stability, as confirmed by cohesive energy, phonon dispersion, and molecular dynamics simulations. The monolayer displays metallic behavior and a high Young's modulus of 250.46 N/m. Upon sodium decoration, strong chemisorption occurs with a binding energy of -2.08 eV and minimal tendency for Na atom clustering. Hydrogen adsorption analysis reveals that each Na atom can bind up to five H$_2$ molecules, resulting in a gravimetric storage capacity of 9.52 wt\%. The calculated H$_2$ adsorption energies range from -0.22 eV to -0.18 eV, falling within the ideal range for reversible adsorption under ambient conditions. These findings highlight Na-decorated TPHE-graphene as a structurally robust and efficient hydrogen storage material well-suited for future green energy applications.