Nano-porous iridium and iridium oxide thin films formed by high efficiency electrodeposition

Sawy, Ehab N. El; Birss, Viola I.

doi:10.1039/b914662h

Cited by 87 publications

(75 citation statements)

References 47 publications

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“…During the potential cycling of the electrode in the activation procedure, a hydrous Ir oxide layer is most likely created, similar to what has been found previously in literature [29,45,46]. The high oxidation and reduction charges around 1 V may then be attributed to the change of oxidation state of Ir within the oxide, which has been described in literature [29,41,42,[47][48][49]. When the electrode is cycled further, the charges in the oxide region decrease significantly.…”

Section: Electrochemical Resultssupporting

confidence: 65%

“…Model thin film electrodes with Pt deposited on a thin metallic layer of Ir was prepared. It is however well known that Ir can form irreversible thick layers of Ir oxides when cycled to higher potentials [41,42], which may influence the properties. The impact of different amounts of Ir on the activity and long-term stability of these electrodes is examined in a fuel cell.…”

Section: Introductionmentioning

confidence: 99%

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The impact of iridium on the stability of platinum on carbon thin-film model electrodes

Wesselmark¹,

Wickman²,

Lagergren³

et al. 2013

Electrochimica Acta

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a b s t r a c tIncreasing the stability and lifetime of the electrodes is one of the most important factors in order to realise a large scale use of polymer electrolyte membrane fuel cells (PEMFC). By using well-defined thin-film model electrodes, the stability of Pt and Pt on Ir were examined as cathode catalysts in a single cell PEMFC setup. The electrodes were fabricated by evaporating thin layers of Pt and Pt on Ir onto the microporous layer of a gas diffusion layer. The amount of Pt deposited was equivalent to 3 nm (about 6.3 g cm −2 ) and the amount of Ir was varied between 1.5 nm and 20 nm (between 3.4 g cm −2 and 45.3 g cm −2 ). All samples with Ir showed an increased stability over samples with sole Pt during cyclic corrosion test between 0.6 V and 1.2 V vs. the reversible hydrogen electrode. For thin layers of Ir, the initial activity for the oxygen reduction reaction was equal to or superior to that of sole Pt but for thicker Ir films it was somewhat lower. Hydrogen underpotential deposition and CO stripping were used to estimate the electrochemical surface area during the experiments and physical characterisation using scanning electron microscopy and X-ray photoelectron spectroscopy were used to determine the structure of the samples. The results suggest that Ir can stabilise Pt in the cathode electrode.

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Section: Electrochemical Resultssupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

The impact of iridium on the stability of platinum on carbon thin-film model electrodes

Wesselmark¹,

Wickman²,

Lagergren³

et al. 2013

Electrochimica Acta

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show abstract

“…1), it is unlikely that a direct tunnelling current is responsible for this result. The experiment indicated that the Ir precursors are not reduced by H 2 molecules but may be reduced by H atoms 34,35 . …”

Section: Discussionmentioning

confidence: 99%

Hydrogen-atom-mediated electrochemistry

Lee

et al. 2013

Nat Commun

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“…12 Inset: The correlation between the Ir at % in the Pt x Ir y NPs and the electron binding energy (BE) of the Ir 4f 7/2 electrons in comparison with the BE of Ir 0 (red circle) 36 and IrOx (green up-triangle). 37 air. Figure S1 shows that the final weight of the samples (10 wt%) matches the original (calculated) weight percent of Pt x Ir y , Ir, or Pt on VC in all cases, confirming that 10 wt% loading is the correct value for all of the catalysts studied here.…”

Section: Resultsmentioning

confidence: 99%

Understanding the Role of Ir during Methanol Oxidation at Pt_xIr_yAlloy Nanoparticles

Sawy

Birss

2017

J. Electrochem. Soc.

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The formation of Pt x Ir y alloy nanoparticles (NPs), having a controlled bulk and surface composition over a wide range of Ir content (35-90 at% Ir), was reported in our recent work. While this prior work did examine the activity of these NPs toward the methanol oxidation reaction (MOR), this was done only per mass of catalyst and only under RT conditions. Here, the MOR activity is reported based on the real surface area of the NPs, determined using several electrochemical methods as well as TEM analysis, in both room temperature (RT) and 60 • C methanol-containing 0.5 M H 2 SO 4 solutions. These more comprehensive results suggest that the bi-functional effect of Ir on Pt activity plays the most significant role in catalyzing the MOR, with the optimum Ir content found to be ca. 35 at% and 50 at% at low and high potentials, respectively, at both temperatures. This demonstrates that less Ir is needed when the CO production rate is low, as is the case for methanol oxidation at the low potentials desired in operating direct methanol fuel cells.

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Nano-porous iridium and iridium oxide thin films formed by high efficiency electrodeposition

Cited by 87 publications

References 47 publications

The impact of iridium on the stability of platinum on carbon thin-film model electrodes

The impact of iridium on the stability of platinum on carbon thin-film model electrodes

Hydrogen-atom-mediated electrochemistry

Understanding the Role of Ir during Methanol Oxidation at Pt_xIr_yAlloy Nanoparticles

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Nano-porous iridium and iridium oxide thin films formed by high efficiency electrodeposition

Cited by 87 publications

References 47 publications

The impact of iridium on the stability of platinum on carbon thin-film model electrodes

The impact of iridium on the stability of platinum on carbon thin-film model electrodes

Hydrogen-atom-mediated electrochemistry

Understanding the Role of Ir during Methanol Oxidation at PtxIryAlloy Nanoparticles

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Understanding the Role of Ir during Methanol Oxidation at Pt_xIr_yAlloy Nanoparticles