Theoretical Study of Twinning Boundaries in Twinned Gold Nanorod Using Evolutionary Algorithms Aided Computational Simulations

Abstract

Fivefold twinned gold nanorods have been widely used in many different fields. It is crucial to understand their twinning structures and related activities. In this work, we conducted computational simulations of the twinning boundaries of the 5-fold twinned gold nanorod, which consists of five single crystal regions and one irregular boundary region with a 7.5° wedge angle. Force-field calculations aided by an evolutionary algorithm based optimization scheme were performed to extensively sample the twinning boundary structures, and several analytical schemes were used to describe the differences among the various located structures, which also help better understand their relationship with stabilities. Moreover, adsorptions of probe molecules at different regions of the twinned gold nanorods, as well as those at single crystalline Au surfaces, were also calculated to illustrate their catalytic activities. The calculated results show that the charge transfer from the twinning boundary to the single crystal regions occurs due to its irregular atomic arrangement, and the accumulated electrons at the single crystal regions can significantly increase their surface activities.