Direct electrochemistry of nanoparticulate Fe2O3 in aqueous solution
and adsorbed onto tin-doped indium oxide*
Katy J. McKenzie and Frank Marken
Department of Chemistry, Loughborough University, Loughborough,
Leicestershire, LE11 3TU, UK
Abstract: Nanoparticulate iron oxides occur naturally, for example,
in soil, water, and in the cytoplasm of living cells. The redox properties
and detection of these nanoparticles are therefore of considerable importance.
Understanding and mimicking nanoparticle-based redox reactions may lead
to new types of water-based electrochemical processes. In this study,
the electrochemical detection of 45 nm diameter Fe2O3 nanoparticles
dissolved in aqueous buffer solutions is investigated as a model system.
Voltammetric experiments with nanoparticulate Fe2O3 are reported based
on two complementary approaches: (i) Fe2O3 nanoparticles adsorbed onto
tin-doped indium oxide (ITO) electrodes are shown to give well-defined
voltammetric reduction responses and (ii) hydrodynamic voltammety in
the presence of fast (24 kHz ultrasound-enhanced) mass transport is
shown to allow the direct detection of Fe2O3 nanoparticles in solution.
Both the adhesion and the electrochemical reactivity of Fe2O3 nanoparticles
at ITO electrode surfaces are strongly affected by the solution composition
and the pH.
* An issue of reviews and research papers based on
presentations made at the IUPAC/ICSU Workshop on
Electrochemistry and Interfacial Chemistry in Environmental Clean-up
and Green Chemical Processes, Coimbra, Portugal, 6-7 April, 2001.
** Corresponding author.
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