In Situ X-ray Absorption Spectroscopic Study of the Adsorption of Ni2+ on Fe3O4 Nanoparticles in Supercritical Aqueous Fluids
In situ X-ray absorption spectroscopy (XAS) measurements were made on Fe3O4 nanoparticles in supercritical aqueous fluids to study their reactivity with Ni2+ ions and to investigate the structural properties of the reacted nanoparticles. XAS spectra were measured from Ni2+ added to an aqueous solution containing Fe3O4 nanoparticles at temperatures up to 500 °C. The XANES and the EXAFS data indicate that reactivity of Fe3O4 nanoparticles with Ni2+ ions is negligible to 300 °C but becomes significant in the 400-500 °C temperature range. Analysis of Ni K-edge extended X-ray absorption fine structure (EXAFS) using an atomic cluster model based on the spinel structure shows that Ni2+ adsorbs predominantly on octahedral sites of the surface of nanoparticles in aqueous fluids at 400-500 °C. The EXAFS structural results are consistent with diffusion of Ni into the near-surface region of the Fe3O4 nanoparticles in the aqueous fluid at 400 and 500 °C.
Physics, Astronomy, and Materials Science
X-ray absorption near edge spectroscopy, nanoparticles, ions, extended X-ray absorption fine structure, fluids
Mayanovic, Robert A., Hao Yan, Alan J. Anderson, Peter R. Meredith, and William A. Bassett. "In situ X-ray absorption spectroscopic study of the adsorption of Ni2+ on Fe3O4 nanoparticles in supercritical aqueous fluids." The Journal of Physical Chemistry C 116, no. 3 (2012): 2218-2225.
The Journal of Physical Chemistry C