Influence of\nParticle Size on Mass Transport during\nthe Oxygen Reduction Reaction at Single Silver Particles Using Scanning\nElectrochemical Cell Microscopy

Single entity electrochemical measurements enable insight\ninto\nthe electrocatalytic activity of individual particles based on composition,\nshape, and crystallographic orientation. In addition to structural\neffects, particle size can further influence electrocatalytic activity\nand reaction mechanisms through mass transport effects. In this work,\nelectrodeposition was used to grow well-separated silver particles\nof varying sizes from 100 to 500 nm in radius. Using a multimicroscopy\napproach of scanning electrochemical cell microscopy combined with\nscanning electron microscopy, the electrocatalytic current of individual\nsilver particles toward the oxygen reduction reaction was evaluated\nas a function of their size. It was found that the current density\nincreased with decreasing particle radius, which was correlated to\nthe mass transport of oxygen to the silver particle, demonstrating\nthe importance of size dependent mass transport effects that can occur\nat the single particle level using scanning electrochemical cell microscopy\nand opening new opportunities for quantitative electrocatalysis measurements.