Nanoparticle–electrode impacts: the oxidation of copper nanoparticles has slow kinetics

Abstract

The electrochemical oxidation of copper nanoparticles in aqueous solution was studied via their electrolysis upon impacting a carbon electrode held at a suitable anodic potential. The oxidations were found to be quantitative such that complete oxidation of the particle took place allowing their sizing. Experiments were performed in 1.0 M HNO₃ and in 1.0 M HNO₃–0.1 M KCl. In the former case a two electron oxidation to Cu²⁺ was seen at a formal potential of +0.11 V (vs. SCE). In the latter case two separate one-electron oxidations at −0.01 V and +0.26 V were seen. In addition, theoretical results were derived for the analysis of impact-charge vs. potential data for reversible and irreversible charge transfer kinetics for nanoparticle oxidation. This enabled the inference that overpotential is required for the oxidations and Butler–Volmer transfer coefficients to be determined. The latter are compared with literature data seen for macroscopic copper.