Use of anodic stripping voltammetry to study the size-selective electrophoretic deposition and aggregation-dependent oxidation of metal nanoparticles.

Abstract

This dissertation describes how anodic stripping voltammetry (ASV) was used to study size-controlled electrophoretic deposition (EPD) and the aggregation-dependent oxidation properties of citrate-stabilized Au nanoparticles (NPs). EPD of citrate-coated Au NPs occurs in the presence of hydroquinone (HQ) onto indium-tin-oxide-coated glass electrodes (glass/ITO) at potentials positive of the HQ oxidation potential. HQ oxidation produces protons at the electrode surface, which serve to neutralize the citrate molecules that electrostatically stabilize the Au NPs. Neutralization leads to the loss of stabilization and deposition onto the electrode. EPD in the presence of ferrocyanide, a non-proton-producing molecule, at oxidation potentials resulted in no deposition of Au NPs, confirming the proton neutralization deposition mechanism. ASV provides information about the aggregation-dependent oxidation of 4 nm, 15 nm, and 50 nm diameter citrate-coated Au NPs. The oxidation potential for well-separated NPs decreases with decreasing size in the order 4 nm