Studying the oxygen reduction and hydrogen oxidation reactions under realistic fuel cell conditions

Kucernak, Anthony; Toyoda, Eishiro

doi:10.1016/j.elecom.2008.09.001

Cited by 54 publications

(41 citation statements)

References 9 publications

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“…This value falls to the 15 high end of the range of specific current densities at 0.9 V vs. RHE previously reported 7,45,46 for RDE and fuel cell apparatus after correcting for temperature (literature values are reported at 60 °C, while this study was carried out at 25 °C). On the cathodic scan, the current density was reduced to 0.105 mA cm -2 Spec .…”

Section: Oxygen Reduction Reactionsupporting

confidence: 54%

“…Even at the rotation rate limit of ~10K rpm, the limiting mass transport currents 55 densities are only 14 and 6 mA cm -2 Geo for the ORR and HOR, respectively. 7 PEFCs operating with pure hydrogen and oxygen can have current densities up to three orders of magnitude higher than this. Therefore, data from the RDE is extrapolated to PEFC current densities, which can introduce significant errors.…”

Section: Introductionmentioning

confidence: 94%

“…7,30,44 At 0.9 V vs. RHE, the anodic scan has a current density of 0.282 mA cm - multilayer coverage of catalyst), the average current density was 31 ± 9 mA cm -2 Spec (28 ± 8 A mg -1 Pt ) for the anodic scan. Below 0.6 V vs. RHE the voltammogram became somewhat linear.…”

Section: Oxygen Reduction Reactionmentioning

confidence: 99%

“…However, Kuhn et al 19 separated the contributions with a pseudo reference electrode 25 sandwiched between the electrodes and found that the HOR impedance was not negligible under their conditions, but of the same order of magnitude across the entire cell impedance range. Lastly, it is challenging to minimize concentration gradients of reactants, products and water distribution across a flow field of a 30 PEFC, generally from the inlet to the outlet 7 and also under channel and land. 20,21 Therefore, the current distribution across the electrode has an element of inhomogeneity.…”

Section: Introductionmentioning

confidence: 99%

“…7,30,44 At 0.9 V vs. RHE, the anodic scan has a current density of 0.282 mA cm -2 Spec , corresponding to a value of 0.25 A mg -1…”

mentioning

confidence: 99%

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Electrocatalytic performance of fuel cell reactions at low catalyst loading and high mass transport

Zalitis

Kramer

Kucernak

2013

Phys. Chem. Chem. Phys.

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175

194

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An alternative approach to the rotating disk electrode (RDE) for characterising fuel cell electrocatalysts is presented. The approach combines high mass transport with a flat, uniform, and homogeneous catalyst deposition process, well suited for studying intrinsic catalyst properties at realistic operating conditions of a polymer electrolyte fuel cell (PEFC). Uniform catalyst layers were produced with loadings as low as 0.16 μg Pt cm -2 and thicknesses as low as 200 nm. Such ultra thin catalyst layers are considered 10 advantageous to minimize internal resistances and mass transport limitations. Geometric current densities as high as 5.7 A cm -2 Geo were experimentally achieved at a loading of 10.15 μgPt cm -2 for the hydrogen oxidation reaction (HOR) at room temperature, which is three orders of magnitude higher than current densities achievable with the RDE. Modelling of the associated diffusion field suggests that such high performance is enabled by fast lateral diffusion within the electrode. The electrodes operate over a wide 15 potential range with insignificant mass transport losses, allowing the study of the ORR at high overpotentials. Electrodes produced a specific current density of 31 ± 9 mA cm -2Spec at a potential of 0.65 V vs. RHE for the oxygen reduction reaction (ORR) and 600 ± 60 mA cm -2 Spec for the peak potential of the HOR. The mass activities of Pt/C catalysts towards the ORR was found to exceed a range of literature PEFC mass activities across the entire potential range. The HOR also revealed fine structure in 20 the limiting current range and an asymptotic current decay for potentials above 0.36 V. These characteristics are not visible with techniques limited by mass transport in aqueous media such as the RDE. IntroductionUnderstanding the kinetics of the oxygen reduction reaction 25 (ORR) and hydrogen oxidation reaction (HOR) on platinum nano-particles is vital for polymer electrolyte fuel cell (PEFC) development. Each platinum nano-particle within the electrode should have optimal proton access, gas access and an electronic path to study intrinsic electrocatalytic properties of the catalyst. 30 These three criteria should be maintained throughout the working conditions (e.g., temperature, humidity and potential). If a reaction site is starved for any of the three, its activity will be reduced, which skews the average activity and introduces an error. It is paramount to minimize the number of underperforming 35 catalyst sites to determine intrinsic catalyst properties. Ideally, the catalyst layer should be made as thin as possible. Thus, all the catalyst particles will be close to the perfluorosulfonic acid (PFSA) membrane for ionic access and close to the gas diffusion layer (GDL) for gas access and an electronic path, removing 40 internal limitations. Mass transport limitations lead to concentration polarization across thick electrodes, 1-3 limiting the active thickness to about 5 μm at high current densities, regardless of how thick the catalyst layer is. 1 The majority of ORR and ...

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Section: Oxygen Reduction Reactionsupporting

confidence: 54%

Section: Introductionmentioning

confidence: 94%

Section: Oxygen Reduction Reactionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…7,30,44 At 0.9 V vs. RHE, the anodic scan has a current density of 0.282 mA cm -2 Spec , corresponding to a value of 0.25 A mg -1…”

mentioning

confidence: 99%

See 3 more Smart Citations

Electrocatalytic performance of fuel cell reactions at low catalyst loading and high mass transport

Zalitis

Kramer

Kucernak

2013

Phys. Chem. Chem. Phys.

Self Cite

175

194

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Quantifying the Kinetic Parameters of Fuel Cell Reactions

Saveleva,

Herranz,

Schmidt

2023

Electrocatalysis for Membrane Fuel Cells

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Limiting Current Density of Oxygen Reduction under Ultrathin Electrolyte Layers: From the Micrometer Range to Monolayers

Zhong

Schulz²,

Wu³

et al. 2021

ChemElectroChem

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The oxygen reduction reaction (ORR) under ultrathin electrolyte layers is a key reaction in many processes, from atmospheric corrosion to energy conversion in fuel cells. However, the ORR current under ultrathin electrolyte layers is difficult to measure using conventional electrochemical methods. Hence, reliable data are scarce for the micrometer range and totally missing for the sub‐micrometer range of the electrolyte layer thickness. Here, we report a novel hydrogen‐permeation‐based approach to measure the ORR current underneath thin and ultrathin electrolyte layers. By using a Kelvin‐probe‐based measurement of the potential, which results from dynamic equilibrium of oxygen reduction and hydrogen oxidation, and the corresponding hydrogen charging current density, the full current‐potential relationship can be constructed. The results shed a new light on the nature of the limiting current density of ORR underneath ultrathin layers of electrolyte.

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Studying the oxygen reduction and hydrogen oxidation reactions under realistic fuel cell conditions

Abstract: 04.09.12 KB. Accepted version ok to add spiral, Elsevier says ok while mandate is not enforced

Cited by 54 publications

References 9 publications

Electrocatalytic performance of fuel cell reactions at low catalyst loading and high mass transport

Electrocatalytic performance of fuel cell reactions at low catalyst loading and high mass transport

Quantifying the Kinetic Parameters of Fuel Cell Reactions

Limiting Current Density of Oxygen Reduction under Ultrathin Electrolyte Layers: From the Micrometer Range to Monolayers

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