Graphsene: a new porous two-dimensional carbon-based material with anisotropic behavior in electronic and mechanical properties and highly efficient ORR electrocatalytic activity

Abstract

Graphene allotropes featuring diverse carbon arrangements have substantial attention due to their unique properties and desired chemical activity. This study introduces a novel two-dimensional carbon-based material, termed Graphsene (GrS), on a theoretical basis. GrS is composed of tetra-, penta-, and dodeca-carbon rings. Formation energy calculations reveal that GrS exhibits superior structural stability compared to synthesized graphene allotropes, including the graphyne and graphdiyne families. Phonon dispersions suggest that the proposed nanosheet is dynamically stable and this material has a relatively small thermal conductivity. All calculated GrS elastic constants satisfy Born criteria, ensuring the mechanical stability of this carbonaceous monolayer. Ab-initio molecular dynamic simulations confirm that GrS retains its original structure at 300K. HSE06 calculations predict a narrow electronic bandgap of 20 meV. A highly anisotropic Dirac-like cone was found in the electronic band structure of GrS which is attributed to the intrinsic structural anisotropy of the nanosheet along armchair and zigzag. Notably, it is predicted that the studied nanosheet exhibits superior catalytic performance for the oxygen reduction reaction (ORR), showcasing a pronounced preference for the four-electron reduction pathway selectivity under both acidic and alkaline conditions. This work presents a promising avenue for the development of metal-free catalyst materials for clean energy production.