Carbon Surfaces with Non-Hexagonal Structure: Stability and Sorption Ability

This paper reports a comparative study of lithium and zinc adsorption on the surfaces of 2D carbon allotropes (biphenylene, irida-graphene, ψ-graphene and TPDH-graphene) using the density functional theory method. The cohesion energies of carbon monolayers and the binding energies of metal atoms with different carbon rings were calculated. All of the considered structures are characterized by cohesive energies close to those of graphene, but with a lower modulus, which indicates their lower thermodynamic stability. Lithium adsorption on the studied allotropes is always more favorable energetically than on graphene, with the energy being higher than the cohesive energy. Conversely, zinc manifests a weak interaction with carbon surfaces and its binding energies are significantly lower than the cohesive energies, indicating a tendency towards clusterization. The example of lithium adsorption on graphene shows that clusterization tendency cannot be estimated from cohesive energy values alone. Therefore, electrostatic repulsion of lithium ions plays a decisive role in the case of the lithium dimer.