CPOS Seminar: Investigating the Interplay between Applied Potential and Precision of Particle Sizing in Single-Entity Blocking Electrochemistry

Speaker: Eric Liu , PhD Student, Department of Chemistry and Biochemistry, UCSB

Abstract:   Blocking electrochemistry, a subfield of single-entity electrochemistry, enables in-situ sizing of a wide range of redox-inactive particles. This method uses the adsorptive impact of individual insulating particles on a microelectrode which decrease the electrochemical active surface area of the electrode. When there is an electroactive redox species in solution, each individual impacting particle results in discrete current drops, and the magnitude of the drop corresponds to the size of the particle blocking the electrode surface. One significant limitation of this technique is the “edge-effects.” This exists because of the inhomogeneous flux of the redox species’ diffusion due to increased mass transport onto the edge of the disk electrode surface. “Edge-effects” cause increased errors in size detection, and results in poor analytical precision. We demonstrate that moving away from where the system is operating under diffusional regime, and towards a kinetic regime by changing the applied potential increases the precision significantly. In addition, we demonstrate that this method of precision enhancement is not limited to spheres but also occurs for cubes. This work presents a novel methodology for edge effect mitigation of incredible simplicity, and shows its universality among different particle types.