Plasmonic\nImaging of Electrochemical\nOxidation of Single Nanoparticles

Abstract

Measuring\nelectrochemical activities of nanomaterials is critical\nfor creating novel catalysts, for developing ultrasensitive sensors,\nand for understanding fundamental nanoelectrochemistry. However, traditional\nelectrochemical methods measure a large number of nanoparticles, which\nwash out the properties of individual nanoparticles. We report here\na study of transient electrochemical oxidation of single Ag nanoparticles\nduring collision with an electrode and voltammetry of single nanoparticles\nimmobilized on the electrode using a plasmonic-based electrochemical\ncurrent microscopy. This technique images both electrochemical reaction\nand size of the same individual nanoparticle, enabling quantitative\nexamination of size-dependent electrochemical activities at single\nnanoparticle level. The imaging capability further allows detection\nof the reaction kinetics of each individual nanoparticle and analysis\nof the average behaviors of multiple nanoparticles. The average kinetics\nand size dependence can be accurately described by the Tafel equation,\nbut there is a large variability between different nanoparticles,\nwhich underscores the importance of single nanoparticle analysis.