Vibrational Spectroscopy of the Ionomer–Catalyst Interface

Kendrick, Ian; Doan, Jonathan; Smotkin, Eugene S.

doi:10.1002/9781118658871.ch10

Cited by 5 publications

(5 citation statements)

References 41 publications

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“…It is stemmed from the reduced hydrogen bonding interactions between -SO 3 À and H 2 O. The former one can be attributed to the rocking vibration of -COC-(A), 49 while the exact assignment of the latter one is still in controversy. For a hydrated Nafion membrane, H 2 O mainly exists in the hydrophilic (-SO 3 À ) n domains.…”

Section: Resultsmentioning

confidence: 99%

“…39 It is noteworthy that the dehydration process leads to the appearance of two new IR peaks at 915 cm À1 and 1415 cm À1 . The former one can be attributed to the rocking vibration of -COC-(A), 49 while the exact assignment of the latter one is still in controversy. 39,50 The unavoidable alkyl impurities in the original Nafion solution may contribute to the IR absorption here due to the bending vibrations of CH (1/2/3) .…”

Section: Analyses Of Conventional 1d Ftir Spectra and 1d Tga Curvesmentioning

confidence: 99%

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Does thermal treatment merely make a H₂O-saturated Nafion membrane lose its absorbed water at high temperature?

Feng

Hou

Tang

et al. 2015

Phys. Chem. Chem. Phys.

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Investigating the dehydration process of a Nafion membrane helps to understand the mechanism of the decrease in its proton conductivity under high-temperature and low-humidity conditions. Herein, the influence of thermal treatment on a H2O-saturated Nafion membrane was in situ studied by FTIR spectroscopy. With the aid of generalized two-dimensional correlation spectroscopy (2Dcos), the microstructural changes during the thermal treatment were discussed in detail. In short, side-chain regions first lost H2O, followed by the H2O loss in ionic cluster domains. It resulted in shrunken ionic channels in the Nafion membrane, which exhibited a negative influence on its proton conduction. The immediate aftermath was the crystallization of amorphous backbone regions. All these results were confirmed by TGA and XRD techniques, and the 2Dcos method was first applied in TGA and XRD results in this field.

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Section: Resultsmentioning

confidence: 99%

Section: Analyses Of Conventional 1d Ftir Spectra and 1d Tga Curvesmentioning

confidence: 99%

Does thermal treatment merely make a H₂O-saturated Nafion membrane lose its absorbed water at high temperature?

Feng

Hou

Tang

et al. 2015

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…Infrared (IR) spectroscopy, in particular, has proved to be a very powerful experimental technique to study in situ or operando electrocatalytic reactions on metal surfaces, and detect various adsorbed oxygenated species . However, thus far, most reports of in situ spectroscopic studies have been restricted to thin‐film metal surfaces, which cannot replicate features of nanoparticle catalysts, such as size dependence .…”

Section: Figurementioning

confidence: 99%

Adsorbed Intermediates in Oxygen Reduction on Platinum Nanoparticles Observed by In Situ IR Spectroscopy

2018

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The sluggish kinetics of oxygen reduction to water remains as ignificant limitation in the viability of protonexchange-membrane fuel cells,y et details of the four-electron oxygen reduction reaction remain elusive.H erein, we apply in situ infrared spectroscopytoprobe the surface chemistry of ac ommercial carbon-supported Pt nanoparticle catalyst during oxygen reduction. The IR spectra show potentialdependent appearance of adsorbed superoxide and hydroperoxidei ntermediates on Pt. This strongly supports an associative pathway for oxygen reduction. Analysis of the adsorbates alongside the catalytic current suggests that another pathway must also be in operation, consistent with ap arallel dissociative pathway.

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“…[13][14][15][16][17] A hydrated membrane is essential for fuel cell operation. Operando IR spectroscopy 7,[18][19][20][21][22][23][24][25][26][27] requires stringent control of reactant stream humidification, flow rate, and cell temperature to prevent condensed water from overwhelming the IR spectra. Raman micro-spectroscopy, which is tolerant of condensed water, is complementary to FTIR.…”

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confidence: 99%

Operando Raman Micro-Spectroscopy of Polymer Electrolyte Fuel Cells

Kendrick

Fore

Doan

et al. 2016

J. Electrochem. Soc.

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Operando Raman micro-spectroscopy of the membrane electrode assembly (MEA) of a fully operating hydrogen/oxygen Nafion electrolyte fuel cell is described. Coarse depth profiling of the fuel cell system enabled appropriate positioning of the microspectroscopy laser focal point for MEA catalytic layer spectroscopy. An increase in the ionomer state-of-hydration, from oxygen reduction at the cathode, transitions ion exchange sites from the sulfonic acid to the dissociated sulfonate form. Visualization of density functional theory calculated normal mode eigenvector animations enabled assignments of Nafion side-chain vibrational bands in terms of the exchange site local symmetry: C 1 and C 3V modes correlate to the sulfonic acid and sulfonate forms respectively. The gradual transition of the MEA spectra from C 1 to C 3V modes, from the fuel cell open circuit voltage to the short circuit current respectively, demonstrate the utility of vibrational group mode assignments in terms of exchange site local symmetry.

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Vibrational Spectroscopy of the Ionomer–Catalyst Interface

Cited by 5 publications

References 41 publications

Does thermal treatment merely make a H₂O-saturated Nafion membrane lose its absorbed water at high temperature?

Does thermal treatment merely make a H₂O-saturated Nafion membrane lose its absorbed water at high temperature?

Adsorbed Intermediates in Oxygen Reduction on Platinum Nanoparticles Observed by In Situ IR Spectroscopy

Operando Raman Micro-Spectroscopy of Polymer Electrolyte Fuel Cells

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Vibrational Spectroscopy of the Ionomer–Catalyst Interface

Cited by 5 publications

References 41 publications

Does thermal treatment merely make a H2O-saturated Nafion membrane lose its absorbed water at high temperature?

Does thermal treatment merely make a H2O-saturated Nafion membrane lose its absorbed water at high temperature?

Adsorbed Intermediates in Oxygen Reduction on Platinum Nanoparticles Observed by In Situ IR Spectroscopy

Operando Raman Micro-Spectroscopy of Polymer Electrolyte Fuel Cells

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Product

Resources

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Does thermal treatment merely make a H₂O-saturated Nafion membrane lose its absorbed water at high temperature?

Does thermal treatment merely make a H₂O-saturated Nafion membrane lose its absorbed water at high temperature?