Electrochemical Detection of Nanoparticle Collision by Reduction of Silver Chloride

Abstract

We report a new detection scheme to detect and study discrete collisional events of single metal nanoparticles on a carbon ultramicroelectrode (UME). Detection of single nanoparticle collision is based on rapid electrocatalytic reduction of silver chloride (AgCl) on metal nanoparticle surfaces when they diffuse and make electrical contacts with a AgCl-modified carbon UME substrate. Single collisional events can be recorded as individual millisecond current pulses on a carbon UME by a simple square wave voltage waveform. Detections of both 80-nm silver and 4-nm gold nanoparticles are demonstrated in this work. This method is simple yet powerful and allows continuous recording of nanoparticle collision events for hours. Moreover, this method uses surface-supported solid AgCl and does not involve added redox species in the bulk solution. Therefore, nanoparticle stability can be less affected by the presence of other redox species, such as hydrazine.