X-ray absorption in relation to valency of iridium in sputtered iridium oxide films

Pauporté, Thierry; Aberdam, D.; Hazemann, Jean‐Louis; Faure, R.; Durand, Robert

doi:10.1016/s0022-0728(99)00058-3

Cited by 65 publications

(75 citation statements)

References 16 publications

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“…The intensity of the white line peak is generally interpreted as a measure of the number of vacant Ir dstates and thus of the Ir partial oxidation state (charge density around Ir centers). [30][31][32] Therefore, an increase of the white line peak intensity is an indication of the removal of electronic charge from the Ir sites with increasing potentials starting at the onset of OER.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Flow-Cell Setup for In Situ X-ray Investigations

Binninger

Fabbri

Pătru

et al. 2016

J. Electrochem. Soc.

109

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An electrochemical three-electrode flow-cell is presented for in situ small-angle X-ray scattering (SAXS) and X-ray absorption spectroscopy (XAS) experiments in transmission mode at synchrotron X-ray sources. The cell also allows for in situ XAS performed in fluorescence mode. Constant experimental conditions, even under moderate gas evolution, are provided by the electrolyte flow with controlled gas saturation. A special configuration of working and counter electrode, respectively, yields low residual ohmic resistance in three-electrode measurements that enables the study of thick porous electrodes of active high surface area materials. The cell proved its functionality and reliability in two studies: First, an in situ anomalous SAXS experiment for the high-potential degradation properties of a Pt/IrO 2 -TiO 2 catalyst for the oxygen reduction reaction at polymer electrolyte fuel cell cathodes; and second, an in situ XAS study of the electronic state of Ir centers inside an IrO 2 -TiO 2 catalyst under oxygen evolution conditions. © The Author Modern research in electrocatalysis makes extensive use of in situ X-ray techniques that provide information about the structure and the electronic state of catalyst materials under electrochemical potential control. The reason for this is the limited, merely indirect information about the state of the catalyst that can be deduced from purely electrochemical testing like cyclic voltammetry (CV) which often does not allow for an unambiguous interpretation of the data. In order to develop an understanding at a more fundamental level, additional information is required about the potential-dependent state of electrocatalyst materials that can be provided by synchrotron-based techniques like X-ray scattering or X-ray absorption spectroscopy.One example is the investigation of polymer electrolyte fuel cell (PEFC) Pt cathode catalyst degradation. Different mechanisms have been proposed for the loss of electrochemically active Pt surface area (ECSA) that occurs most severely at transient high-potential spikes during PEFC start and stop.1,2 Processes like agglomeration of primary Pt particles due to migration or carbon support corrosion, Pt loss due to dissolution, and growth of primary Pt nanoparticles due to dissolution/redeposition cycles have been considered 3,4 and quantified for different operation conditions and electrochemical environments. The most common technique applied for this purpose is transmission electron microscopy (TEM), which has the convenient advantage that changes of the Pt nanoparticle structure can be directly visualized, especially with the use of identical location TEM (IL-TEM).5 Although successfully demonstrated, 6 in situ TEM remains limited to certain electrochemical systems. Whereas the strength of TEM lies in the direct imaging of individual catalyst particles, it is challenging to extract quantitative statistical information about the entire catalyst sample from TEM analysis. Finally, the distinction of Pt nanoparticles from the support material p...

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Section: Resultsmentioning

confidence: 99%

Electrochemical Flow-Cell Setup for In Situ X-ray Investigations

Binninger

Fabbri

Pătru

et al. 2016

J. Electrochem. Soc.

109

View full text Add to dashboard Cite

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“…Pauporté and his co-workers investigated the valency of iridium ions in sputtered iridium oxide film by X-ray absorption spectroscopy (XAS) at the L 3 edge of iridium atoms in 1 M H 2 SO 4 , and determined the valency of iridium to be 3 to 3.85 when the potential varied from -0.2 to + 1 V (vs SCE) [16]. If we adapt their results to our findings, the valency of the iridium ion at 0.90 V (vs RHE), the E ORR of the Ir 0.6 V 0.4 O 2 /Ti electrode heat-treated at 450°C, corresponds to ca.…”

Section: Resultsmentioning

confidence: 99%

Oxygen reduction behavior of RuO2/Ti, IrO2/Ti and IrM (M: Ru, Mo, W, V) Ox/Ti binary oxide electrodes in a sulfuric acid solution

Takasu

Yoshinaga

Sugimoto

2008

Electrochemistry Communications

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“…It is well known that the white line position in the Ir-L III edge is shifted to higher energy by more than one eV with an increase in the formal valence of Ir ion from 3 + to 4 + . 27,28 In Fig. 3 we compare the Ir-L III absorption spectra of Sr 3 CoIrO 6 and Sr 3 ZnIrO 6 .…”

Section: B X-ray Absorption Spectroscopy Study Of Sr 3 Coiromentioning

confidence: 99%

Magnetic properties and crystal structure of Sr3CoIrO6and Sr3NiIrO
Mikhailova
¹
,
Schwarz
²
,
Senyshyn
³

et al. 2012
Phys. Rev. B

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We have studied the magnetic properties and crystal structure of Sr 3 CoIrO 6 and Sr 3 NiIrO 6 as a function of temperature. Two characteristic temperatures, T 1 = 90 K and T 2 = 25 K for Sr 3 CoIrO 6 , and T 1 = 85 K and T 2 = 15 K for Sr 3 NiIrO 6 , were observed. Below T 1 a significant increase of magnetization and below T 2 a weak temperature dependence of magnetization in the field-cooled and practically zero magnetization values in the zero-field-cooled mode were detected for both compounds. The existence of Ir 4+ in Sr 3 CoIrO 6 was confirmed by an Ir-L III x-ray absorption measurement. Magnetoelastic effects have been observed in the temperature dependence of the lattice parameters of Sr 3 CoIrO 6 and Sr 3 NiIrO 6 . The magnetic structure of Sr 3 CoIrO 6 in zero fields can be described as a commensurate modulated antiferromagnet with a propagation vector k = (0,0,1). Neutron powder diffraction with polarized neutrons gave evidence of short-range magnetic order, above and below the magnetic ordering temperature.

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X-ray absorption in relation to valency of iridium in sputtered iridium oxide films

Cited by 65 publications

References 16 publications

Electrochemical Flow-Cell Setup for In Situ X-ray Investigations

Electrochemical Flow-Cell Setup for In Situ X-ray Investigations

Oxygen reduction behavior of RuO2/Ti, IrO2/Ti and IrM (M: Ru, Mo, W, V) Ox/Ti binary oxide electrodes in a sulfuric acid solution

Magnetic properties and crystal structure of Sr3CoIrO6and Sr3NiIrO
Mikhailova
¹
,
Schwarz
²
,
Senyshyn
³

et al. 2012
Phys. Rev. B

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X-ray absorption in relation to valency of iridium in sputtered iridium oxide films

Cited by 65 publications

References 16 publications

Electrochemical Flow-Cell Setup for In Situ X-ray Investigations

Electrochemical Flow-Cell Setup for In Situ X-ray Investigations

Oxygen reduction behavior of RuO2/Ti, IrO2/Ti and IrM (M: Ru, Mo, W, V) Ox/Ti binary oxide electrodes in a sulfuric acid solution

Magnetic properties and crystal structure of Sr3CoIrO6and Sr3NiIrOMikhailova1, Schwarz2, Senyshyn3 et al. 2012Phys. Rev. B

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Magnetic properties and crystal structure of Sr3CoIrO6and Sr3NiIrO
Mikhailova
¹
,
Schwarz
²
,
Senyshyn
³

et al. 2012
Phys. Rev. B