AVS 53rd International Symposium
    Applied Surface Science Tuesday Sessions
       Session AS+SS-TuM

Paper AS+SS-TuM5
Evolution of Metal-Core Oxide-Shell Iron Nanoparticles as a Function of Time in an Aqueous Environment

Tuesday, November 14, 2006, 9:20 am, Room 2005

Session: Environmental Materials and X-ray Spectroscopies
Presenter: D.R. Baer, Pacific Northwest National Lab
Authors: D.R. Baer, Pacific Northwest National Lab
P.G. Tratnyek, Oregon Health and Sciences Univ.
J.E. Amonette, Pacific Northwest National Lab
C.M. Wang, Pacific Northwest National Lab
M.H. Engelhard, Pacific Northwest National Lab
Y. Qiang, University of Idaho
J.T. Nurmi, Oregon Health and Sciences Univ.
V. Sarathy, Oregon Health and Sciences Univ.
J. Antony, University of Idaho
Correspondent: Click to Email
The high reactivity of metallic iron nanoparticles with contaminants such as chlorinated hydrocarbons, the possibility of solution based delivery to contamination zones and evidence of an ability of the nanostructure to alter reaction pathways have stimulated considerable research into the potential use of iron metal nanoparticles for environmental remediation. As part of our study of the chemical properties of nanoparticles, we are examining how metal-core oxide-shell iron nanoparticles evolve with time in aqueous environments. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and x-ray diffraction (XRD) are used to examine the particles at different times after exposure to water solutions with and without carbon tetrachloride. The influence of formation, processing and analysis conditions on the nature of the core/shell structure has been examined in some detail. The room temperature oxidation of these nanoparticles shows the formation of voids and in some circumstances hollow oxide nanoparticles. Other measurements show that an electron beam damages the oxide shell allowing oxidation to occur in the normal environment of a TEM. Aspects of particle reactivity have been examined by batch reactivity, electrochemical and electron paramagnetic resonance measurements. Studies measuring the reductive dechlorination of carbon tetrachloride (CT) have shown that nanoparticle properties (as well as solution chemistry and other experimental conditions) affect the distribution of products formed. Of particular interest are factors that favor degradation of CT by product formation pathways that do not produce chloroform (CF), which is a persistent and toxic byproduct.