jp0c01447_si_001.pdf (2.26 MB)
Effect of Viscosity on the Collision Dynamics and Oxidation of Individual Ag Nanoparticles
journal contribution
posted on 2020-04-09, 14:42 authored by Donald
A. Robinson, Martin A. Edwards, Yuwen Liu, Hang Ren, Henry S. WhiteWe experimentally
and theoretically explore the effect of viscosity
on the collision dynamics and oxidation of colloidal Ag nanoparticles (NPs) at a Au microdisk electrode.
Building on a previously reported random walk simulation of NP collisions,
we introduce continuum approximations of the ensemble-averaged transient
NP collision frequency and faradaic current arising from a one-dimensional
random walk. The theoretical models incorporate mass-dependent particle
speed from classical kinetic theory and radius/viscosity-dependent
diffusivity from Einstein’s diffusion relations. We demonstrate
that the measured cumulative average charge from the oxidation of
individual Ag NPs scales with the square root of the diffusion coefficient,
in agreement with both random walk simulations and analytical approximations.
Our findings indicate that single-NP diffusion controls the average
rate of electron transfer at the electrode/solution interface.