Gold Nanoparticles Aggregation on Graphene Using Reactive Force Field: A Molecular Dynamic Study

TL;DR

This study uses molecular dynamics simulations with ReaxFF to investigate how gold nanoparticles of various sizes aggregate on graphene at different temperatures, affecting morphology and charge transfer.

Contribution

It provides new insights into size- and temperature-dependent aggregation behavior and charge transfer mechanisms of AuNPs on graphene using ReaxFF simulations.

Findings

Smaller AuNPs exhibit more shape changes upon aggregation.

Larger AuNPs transfer more charge to graphene.

Aggregation depends significantly on nanoparticle size and temperature.

Abstract

We examine the aggregation behavior of AuNPs of different sizes on graphene as function of temperature using molecular dynamic simulations with Reax Force Field (ReaxFF). In addition, the consequences of such aggregation on the morphology of AuNPs and the charge transfer behavior of AuNP-Graphene hybrid structure are analyzed. The aggregation of AuNPs on graphene is confirmed from the center of mass distance calculation. The simulation results indicate that the size of AuNPs and temperature significantly affect the aggregation behavior of AuNPs on graphene. The strain calculation showed that shape of AuNPs changes due to the aggregation and the smaller size AuNPs on graphene exhibit more shape changes than larger AuNPs at all the temperatures studies in this work. The charge transfer calculation reveals that, the magnitude of charge transfer is higher for larger AuNPs-graphene composite when compared with smaller AuNPs-graphene composite. The charge transfer trend and the trends seen in the number of Au atoms directly in touch with graphene are identical. Hence, our results conclude that, quantity of Au atoms directly in contact with graphene during aggregation is primarily facilitates charge transfer between AuNPs and graphene.