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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 (The University of Manchester) , Akihiro Uehara-Kasuno (Kyoto University) , Sin Yuen Chang (The University of Manchester) , J. Fred W. Mosselmans (Diamond Light Source) , Sven L. M. Schroeder (University of Leeds) , Robert A. W. Dryfe (The 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

Added On: 22/07/2015 08:02

Discipline Tags:

Physical Chemistry Chemistry Materials Science Nanoscience/Nanotechnology Metallurgy

Technical Tags:

Imaging Spectroscopy X-ray Fluorescence (XRF) X-ray Absorption Spectroscopy (XAS) Extended X-ray Absorption Fine Structure (EXAFS)