Janus-graphene: a two-dimensional half-auxetic carbon allotropes with non-chemical Janus configuration

TL;DR

Janus-graphene is a novel purely sp2 hybridized carbon monolayer with a non-chemical Janus configuration that exhibits a unique, structure-independent half-auxetic behavior, expanding the functional properties of carbon materials.

Contribution

This work introduces the first non-chemical Janus configuration in a purely sp2 hybridized carbon monolayer, demonstrating unprecedented half-auxeticity.

Findings

Displays structure-independent half-auxetic behavior

Maintains expansion under both stretching and compression

Enriches the functional carbon family for electronic applications

Abstract

The asymmetric properties of Janus two-dimensional materials commonly depend on chemical effects, such as different atoms, elements, material types, etc. Herein, based on carbon gene recombination strategy, we identify an intrinsic non-chemical Janus configuration in a novel purely sp$^2$ hybridized carbon monolayer, named as Janus-graphene. With the carbon gene of tetragonal, hexagonal, and octagonal rings, the spontaneous unilateral growth of carbon atoms drives the non-chemical Janus configuration in Janus-graphene, which is totally different from the chemical effect in common Janus materials such as MoSSe. A structure-independent half-auxetic behavior is mapped in Janus-graphene that the structure maintains expansion whether stretched or compressed, which lies in the key role of $p_z$ orbital. The unprecedented half-auxeticity in Janus-graphene extends intrinsic auxeticity into pure sp$^2$ hybrid carbon configurations. With the unique half-auxeticity emerged in the non-chemical Janus configuration, Janus-graphene enriches the functional carbon family as a promising candidate for micro/nanoelectronic device applications.