Gold in graphene: in-plane adsorption and diffusion

TL;DR

This study uses density-functional theory to analyze gold atom bonding and diffusion in graphene vacancies, revealing preferred adsorption sites, high diffusion barriers, and suggesting radiation-enhanced diffusion mechanisms.

Contribution

It provides detailed theoretical insights into Au in graphene vacancies, highlighting adsorption preferences and diffusion barriers, and proposes a non-thermal diffusion mechanism.

Findings

Au prefers double vacancies for adsorption

Diffusion barriers are above 4 eV for double vacancies

Diffusion likely involves radiation enhancement, not thermal activation

Abstract

We study the bonding and diffusion of Au in graphene vacancies using density-functional theory. Energetics show that Au adsorbs preferably to double vacancies, steadily in-plane with graphene. All diffusion barriers for the complex of Au in double vacancy are above 4 eV, whereas the barriers for larger vacancies are below 2 eV. Our results support the main results of a recent experiment [Gan et al., Small 4, 587 (2008)], but suggest that the observed diffusion mechanism is not thermally activated, but radiation-enhanced.