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Gold Deposition at a Free-Standing Liquid/Liquid Interface: Evidence for the Formation of Au(I) by Microfocus X-ray Spectroscopy (μXRF and μXAFS) and Cyclic Voltammetry

DOI: 10.1021/acs.jpcc.5b05127 DOI Help

Authors: Samuel. G. Booth (University of Manchester) , Akihiro Uehara-kasuno (Division of Nuclear Engineering Science, Research Reactor Institute, Kyoto University) , Sin Yuen Chang (School of Chemical Engineering and Analytical Science, The University of Manchester) , J. Fred W. Mosselmans (Diamond Light Source) , Sven L. M. Schroeder (School of Chemical and Process Engineering, University of Leeds) , Robert A. W. Dryfe (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C , VOL 119 (29) , PAGES 16785–16792

State: Published (Approved)
Published: July 2015
Diamond Proposal Number(s): 8861

Open Access Open Access

Abstract: Electrochemical gold nucleation and nanoparticle growth at a liquid/liquid interface were examined in situ by combined X-ray fluorescence (XRF) mapping with a microfocus X-ray beam and X-ray absorption fine structure (XAFS) spectroscopy. Gold deposition was achieved by reduction of [AuCl4]− with tri-p-tolylamine at a water/1,2-dichlorobenzene interface using a windowless liquid/liquid interface system formed from the contact of aqueous and organic phase droplets. The combination of XRF and XAFS, with a spatial resolution of approximately 70 μm, provided chemical speciation information near the interface under gold deposition conditions. Analysis of the X-ray absorption near-edge structure (XANES) reveals evidence for the presence of Au(I) species as a reduction intermediate, concomitant with a buildup of metallic gold at the interface. Cyclic voltammetry indicates the presence of two ion transfer peaks at the liquid/liquid interface, which are assigned to the transfer of [AuCl4]− and [AuCl2]−. Finally ex situ TEM analysis shows that the resultant nanoparticles have an average size between 3 and 4 nm. In line with this particle size, the XAFS indicates bulk-like structure.

Journal Keywords: Gold Nanoparticles Nucleation

Subject Areas: Chemistry, Materials

Instruments: I18-Microfocus Spectroscopy