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X-ray photoelectron spectroscopy of oxygen-containing layers formed by a linear potential scan on stepped gold (111) films in aqueous 1 M sulphuric acid
X-ray photoelectron spectroscopy (XPS) data of oxygen-containing layers (O-layers) made on stepped gold (111) film electrodes from aqueous 1 M sulphuric acid by single linear potential scans at 0.10 V s − 1 and 298 K are reported. The potential scan covered from the open circuit potential to anodic...
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Published in: | Thin solid films 2009, Vol.517 (5), p.1534-1540 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | X-ray photoelectron spectroscopy (XPS) data of oxygen-containing layers (O-layers) made on stepped gold (111) film electrodes from aqueous 1 M sulphuric acid by single linear potential scans at 0.10 V s
−
1
and 298 K are reported. The potential scan covered from the open circuit potential to anodic switching potential
E
as
=
2.50 V versus normal hydrogen electrode (NHE) and holding times at
E
as in the range 30–300 s. The anodic charge density
q
a determined from the oxidation and reduction voltammetric scan is in the range 0.20
≤
q
a
≤
2.5 mC cm
−
2
. For the potential
E
=
0.5 V, in the absence of O-layers, the S 2p core level spectrum indicates the presence of sulphate/bisulphate adsorbates. For
E
as
>
1.3 V, the O 1s core level spectrum involves the contribution from water, OH- and O-species. These spectra are deconvoluted utilising either three or four Gaussian contributions with values of peaked binding energy and full width at half-maximum height (FWMH) in good agreement with expectations. The envelope of these XPS O 1s signals after correction for the contribution of sulphate/bisulphate adsorbates and adventitious carbon approaches the XPS signal that has been reported for the core level spectrum in the O 1s region of oxidised gold surfaces produced by laser pulses at different molecular oxygen pressures. The O/OH concentration ratio in the O-layer increases with
E
as ageing time
t
ag and cathodic charge density
q
c. The hydrous nature of the O-layer, evaluated through the analysis of the core level spectra in the O 1s region, decreases as
E
as and
t
ag are increased. Results are interesting to unravel the composition and structure of electrochemically grown O-layers at the surface of the gold substrate, and the influence of the history of these O-layers on the respective XPS features. |
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ISSN: | 0040-6090 1879-2731 |
DOI: | 10.1016/j.tsf.2008.09.036 |