Aspect ratio effect of nanorods on heterogeneous nucleation rates by molecular dynamics

Abstract

Heterogeneous nucleation is a prominent phenomenon in the environment and industry. Nanorods have been studied intensively due to a wide range of applications they possess. Here, molecular dynamics is used to analyze how different aspect ratios of a nanorod will affect spontaneous nucleation of droplets within a highly supersaturated vapor system. The results have been compared with previous studies conducted by Suh and Yasuoka (Journal of Physical Chemistry B, 115 10631; Journal of Physical Chemistry B 116 14637), which were about nanospheres and nanocubes, respectively. The previous results showed that the change in seed shape from a sphere to cube did not affect the spontaneous nucleation rate of droplets. This result is natural because the droplet nucleation rates are the number of nuclei that form and the addition of a seed will only act as a single nucleation site regardless of the shape. The addition of a nanorod, however, clearly increases the droplet nucleation rate and this trend is consistent for all aspect ratios exceeding unity. The reason for this increase was verified for greater system sizes and canceling any rotation the nanorod may exhibit. Both cases show that the increase in the nucleation rate persists. Further studies on the origin of the phenomenon will be conducted in future work.