Features of the formation of Fe-Pt nanoalloy particles during the joint reduction of aqueous solutions of Fe2+ and [PtCl6]2- by hydrazine hydrate in an alkaline medium
N. S. ZAKHAROV, A. N. POPOVA, V. M. PUGACHEV, V. G. DODONOV, YU. A. ZAKHAROV
Federal Research Center for Coal and Coal Chemistry, Siberian Branch of Russian Academy of Sciences, Kemerovo, Russia
Keywords: nanoalloys, Fe-Pt, hydrazine hydrate, phase compositions, X-ray diffraction, small-angle X-ray scattering, X-ray photoelectron spectroscopy
Abstract
The scheme of phase formation in Fe-Pt nanoalloy was established using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), including in situ heating, small-angle X-ray scattering (SAXS), and optical emission spectrometry with inductively coupled plasma (ICP-OES). The nanoalloy particles were synthesised using the co-reduction of precursor solutions (Fe2+ and [PtCl6]2-) with an alkaline solution of hydrazine hydrate. To determine the scheme of solid Fe-Pt phase formation, the reduction process was stopped after 10 and 300 s by diluting the reaction mixture with cold (2 °C) water. Comparison of the results obtained using XRD, XPS, SAXS, and ICP-OES methods allowed us to establish that the formation of the solid phase under reduction-oxidation reaction conditions is a staged process. The first and fastest stage is the formation of the Pt-phase with particle sizes ≈3 nm. The second stage involves the joint reduction of platinum and iron precursors on the surface of Pt particles formed at the first stage. The last stage is the formation of ultrafine particles enriched in Fe under the conditions of Pt precursor deficiency.
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