Quick-Scanning EXAFS in the Reflection Mode as a Probe for Structural Information of Electrode Surfaces with Time Resolution:  An in Situ Study of Anodic Silver Oxide Formation

Hecht, D.; Frahm, R.; Strehblow, Hans‐Henning

doi:10.1021/jp9610574

Cited by 32 publications

(32 citation statements)

References 19 publications

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“…Time resolved experiments were performed in the quick-extended X-ray absorption fine structure (QEX-AFS) mode, where the DCM is moved continuously from lower to higher energies and the absorption spectrum is measured simultaneously. 16,17 For the X-ray studies, sputter deposited silver films (thickness ³300 nm) on glass substrates were mounted in an electrochemical cell; details of this cell are given in Ref. 7.…”

Section: Methodsmentioning

confidence: 99%

The anodic oxidation of silver in 1 M NaOH: electrochemistry, ex situ XPS and in situ X‐ray absorption spectroscopy

Lützenkirchen‐Hecht¹,

Strehblow²

2006

Surface & Interface Analysis

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We have investigated the electrochemical formation of oxide layers on silver in 1 M NaOH (pH 13.8) using a combination of electrochemical techniques, X-ray photoelectron spectroscopy (XPS) and surface sensitive grazing incidence X-ray absorption spectroscopy (XAS). While the XPS experiments were performed after the removal of the samples from the electrolyte and transfer into an ultra-high vacuum (UHV) system under inert conditions, the XAS experiments were performed in situ and under full potential control. The application of these techniques leads to a detailed, consistent picture of the anodic oxide layer formation process on silver. All the applied techniques proved that the anodic oxidation starts at potentials lower than the corresponding Nernst potential. Extended X-ray absorption fine structure (EXAFS) investigations suggest that the underpotential Ag + oxide layer of some few nanometres thickness has a rather disordered structure. Time resolved XPS and EXAFS experiments have shown that the growth of these disordered layers is diffusion controlled, i.e. the thickness increases with the square root of the oxidation time. For moderately higher potentials, i.e. slightly above the Nernst equilibrium potential, the thickness of the silver(I) oxide layer increases rapidly with potential and the structure is very similar to that of crystalline Ag 2 O.

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Section: Methodsmentioning

confidence: 99%

The anodic oxidation of silver in 1 M NaOH: electrochemistry, ex situ XPS and in situ X‐ray absorption spectroscopy

Lützenkirchen‐Hecht¹,

Strehblow²

2006

Surface & Interface Analysis

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“…A standard Zn foil was mounted between two ionization chambers, downstream of the sample, to allow the energy to be calibrated using the first inflection point of the Zn foil absorption edge. The XANES and EXAFS scanning step sizes were 0.5 eV/point and 1.0 eV/point, respectively (Hecht et al, 1996). According to the fundamental of SSRF, the uncertainty for XAS measurement is lower than 0.005% (5-20 keV).…”

Section: Xas Measurementsmentioning

confidence: 99%

Characterization of zinc vapor condensation in fly ash particles using synchrotron X-ray absorption spectroscopy

Cai

Huang

Alhadj-Mallah

et al. 2015

J. Zhejiang Univ. Sci. A

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Heavy metals released from municipal solid waste incinerators have become a major environmental concern. A comprehensive knowledge of metal vapor condensation in fly ash particles during incineration is essential for alleviating heavy metal toxicity, and for optimizing incineration process parameters and flue-gas cleaning systems. In this paper, the condensation of zinc vapor during flue-gas cooling in a 200 t/d fluidized bed incinerator and a 150 t/d moving grate incinerator was characterized and comparatively studied using high resolution synchrotron X-ray absorption spectroscopy (XAS). Principal component analysis, target transformation, and linear combination fitting were employed to identify zinc species directly from size fractionated fly ash particles. The chemical reaction behaviors of different zinc species were described by thermodynamic equilibrium simulations. Consistent with previous theoretical analysis and laboratory scale tests, the condensation behavior of zinc in an industrial incineration system is mainly affected by the sulfur/chlorine ratio and the inorganic particulates. It is found that zinc chloride is the major zinc species in a moving grate incinerator but willemite dominates in the fluidized bed incinerator. The high sulfur and silica/alumina particle concentration in the fluidized bed system changes the condensation propensity of vapors of Zn compounds. Adjusting the concentrations of SO 2 in flue-gas can inhibit the formation of zinc chlorides. Silica, alumina, aluminosilicates, and calcium-based compounds are potential sorbents for transforming zinc to less harmful species. To prevent toxic zinc species contained in fine particles from escaping into the atmosphere, wet scrubbers are more suitable for cleaning flue-gases in moving grate incineration systems, while improving the efficiency of dust removal is more important for fluidized bed incineration systems.

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“…The resulting compounds were characterized by X-Ray diffraction confirming the presence of cubic Ag 2 O in the first oxidation step and a mixture of Ag 2 O and AgO in the last one (see figure 2). It should be noted that AgO is not a Ag(II) phase but has been shown to contain Ag(I) and Ag(III) by means of neutron diffraction [16] and EXAFS data [17][18] .…”

Section: Resultsmentioning

confidence: 99%

Oxidación electroquímica de plata y cobre en medio acuoso básico y en hidróxidos fundidos

Tejada-Rosales¹,

Casañ-Pastor²,

Gómez-Romero³

2004

Bol. Soc. Esp. Ceram. Vidr.

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Quick-Scanning EXAFS in the Reflection Mode as a Probe for Structural Information of Electrode Surfaces with Time Resolution: An in Situ Study of Anodic Silver Oxide Formation

Cited by 32 publications

References 19 publications

The anodic oxidation of silver in 1 M NaOH: electrochemistry, ex situ XPS and in situ X‐ray absorption spectroscopy

The anodic oxidation of silver in 1 M NaOH: electrochemistry, ex situ XPS and in situ X‐ray absorption spectroscopy

Characterization of zinc vapor condensation in fly ash particles using synchrotron X-ray absorption spectroscopy

Oxidación electroquímica de plata y cobre en medio acuoso básico y en hidróxidos fundidos

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