New Electrochemical Strategies for Studying Single Nanoparticles

Abstract

This dissertation describes new advances and applications of single nanoparticle collision electrochemistry and is divided into two broad sections. First, new methods are described to overcome longstanding limitations of the collision technique, ranging from expanding the allowable detection conditions to obtaining more accurate single nanoparticle structural characterization measurements. For example, Chapter 2 describes a novel strategy to measure single particle collisions in conditions almost three orders of magnitude more concentrated than previously attainable. This technique facilitated the discovery of a novel process to measure the electroactive surface areas of single platinum nanoparticles. Further, Chapter 3 describes an electrode modification procedure that promotes the adhesion of colliding silver nanoparticles and facilitates their complete oxidative dissolution. This work yielded accurate volumetric measurements for single silver nanoparticles up to 100 nm in diameter, which is improved from the previous limit of 60 nm.The second half of the dissertation develops new applications for closed-bipolar electrochemical imaging, a methodology that enables the widescale mapping of redox environments with wireless electrode arrays. Chapter 4 demonstrates the first reported optical detection of short-lived transient events using closed-bipolar imaging in which platinum nanoparticle collisions catalyzing the hydrogen evolution reaction are employed as the source of transient electron transfer. Chapter 5 shows progress toward the optical detection of transient oxidative events using silver nanoparticle oxidative collisions as a model system toward the future goal of mapping biological exocytosis in-vitro. Lastly, Chapter 6 demonstrates the spatial mapping of multiple electrochemical processes using a massive array of closed-bipolar electrodes in conjunction with electrochemiluminescence imaging.