Solution
Voltammetry of 4 nm Magnetite Iron Oxide
Nanoparticles
- Publication date
- Publisher
Abstract
The
voltammetry of solution-dispersed magnetite iron oxide Fe<sub>3</sub>O<sub>4</sub> nanoparticles is described. Their currents are
controlled by nanoparticle transport rates, as shown with potential
step chronoamperometry and rotated disk voltammetry. In pH 2 citrate
buffer with added NaClO<sub>4</sub> electrolyte, solution cyclic voltammetry
of these nanoparticles (average diameter 4.4 ± 0.9 nm, each containing
ca. 30 Fe sites) displays an electrochemically irreversible oxidation
with <i>E</i><sub>PEAK</sub> at ca. +0.52 V and an irreversible
reduction with <i>E</i><sub>PEAK</sub> at ca. +0.2 V vs
Ag/AgCl reference electrode. These processes are presumed to correspond
to the formal potentials for one-electron oxidation of Fe(II) and
reduction of Fe(III) at their different sites in the magnetite nanoparticle
structure. The heterogeneous electrode reaction rates of the nanoparticles
are very slow, in the 10<sup>–5</sup> cm/s range. The nanoparticles
are additionally characterized by a variety of tools, e.g., TEM, UV/vis,
and XPS spectroscopies