Stability of quasi-two dimensional zigzag carbon and its reaction pathway to graphene

TL;DR

This study uses density functional theory to explore a stable quasi-two-dimensional zigzag carbon allotrope, ZzC, and its reaction pathway to graphene, revealing intermediate states and stability conditions.

Contribution

It introduces the stable ZzC structure, analyzes its formation pathway to graphene, and examines its behavior upon hydrogenation, providing new insights into carbon allotrope transformations.

Findings

ZzC is stable with a binding energy of 7.46 eV per atom.

Reaction pathway from ZzC to graphene involves carbyne as an intermediate.

Hydrogenation causes ZzC to dissociate into polyacetylene chains.

Abstract

Using the density functional theory we investigate a quasi-two dimensional carbon allotrope, ZzC, formed by square carbon lattice buckled in zigzag manner. By analyzing the Kohn-Sham energy and phonon dispersion obtained by lattice dynamical calculations we show that ZzC is stable with binding energy of 7.46 eV per atom. To examine the possible route of formation we find out reaction pathway from ZzC to graphene using nudge elastic band method, generalized for solid state calculations. The reaction pathway shows the formation of carbyne as the intermediate state. Such a pathway is seen to exhibit two transitions states with reaction barriers of 0.21 eV/atom from ZzC to carbyne, and of 1.19 eV/atom from graphene to carbyne. Although ZzC is stable, upon hydrogenation it dissociates and prefers the carbyne-like structure by forming chains of polyacetylene.