Oxygen Reduction on Ru[sub 1.92]Mo[sub 0.08]SeO[sub 4], Ru/Carbon, and Pt/Carbon in Pure and Methanol-Containing Electrolytes

Schmidt, Thomas J.; Paulus, Ursula A.; Gasteiger, Hubert A.; Alonso‐Vante, Nicolas; Behm, R. J.

doi:10.1149/1.1393579

Cited by 227 publications

(181 citation statements)

References 20 publications

(35 reference statements)

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] Because of the sluggish ORR kinetics and the stability issues of the catalyst in the electrochemical environment, expensive precious metal catalysts are often used in these electrochemical devices to catalyze the ORR. 15 Conventionally, the performance of the catalyst is evaluated in an operating fuel cell mode using the DC methods.…”

mentioning

confidence: 99%

Electrochemical Impedance Spectroscopy of Oxygen Reduction Reaction (ORR) in a Rotating Disk Electrode Configuration: Effect of Ionomer Content and Carbon-Support

Singh

Devivaraprasad

Kar

et al. 2015

J. Electrochem. Soc.

159

112

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Oxygen reduction reaction (ORR) in acidic media is investigated at various potentials in a thin-film rotating disk electrode (TF-RDE) configuration using electrochemical impedance spectroscopy (EIS). The ionomer-free and ionomer-containing thin-film catalyst layers are composed of Pt black and carbon-supported Pt catalysts of different metal loadings (5 and 20 wt%). The simplest EI spectrum consisting of an arc or a semi-circle is obtained at high potentials with ionomer-free Pt catalyst layers. The most complex spectrum consisting of a high frequency (HF) arc and two semi-circles is observed in the mixed diffusion-controlled region of the ionomer-containing catalyst layer with high loading of carbon-supported Pt. The nature of the EI spectrum is decided by the constituents of the thin-film catalyst layer and by the operating potential. The evolution of the EI spectra with ionomer and carbon contents is underlined. The effect of rotation rate (rpm) of the electrode on the impedance spectrum is also investigated. A series of equivalent circuits is required to completely describe the EI spectra of ORR. The kinetic parameters and the electrochemical surface area of the catalysts are derived from the impedance spectrum. Oxygen reduction reaction (ORR) is one of the most important reactions at the cathode side in low-temperature fuel cells (e.g., polymer electrolyte fuel cells (PEFCs) and direct methanol fuel cells (DMFCs)) and metal-air batteries.1-14 Because of the sluggish ORR kinetics and the stability issues of the catalyst in the electrochemical environment, expensive precious metal catalysts are often used in these electrochemical devices to catalyze the ORR. 15 Conventionally, the performance of the catalyst is evaluated in an operating fuel cell mode using the DC methods. [16][17][18] The information gathered from a DC analysis usually provides the sum of various polarizations of the electrode, which is difficult to separate into individual contributions. 19 On the other hand, electrochemical impedance spectroscopy (EIS), one of the AC methods, is a sensitive tool to investigate electrode-electrolyte interface and it allows the simultaneous resolution of various charge-transfer and mass-transfer processes (kinetic, ohmic, and diffusion). It involves a small sinusoidal electrical perturbation around a steady-state value and measures the impedance along with the phase angle. However, the interpretation of the EI spectra is difficult. Often, simple fitting models based on equivalent circuit analogues and physical models are used to extract the parameters those represent the underlying cell processes. [20][21][22][23][24][25][26] Springer et al. proposed the theoretical impedance spectrum of ORR on porous gas-diffusion electrode using the flooded-agglomerate electrode model in series with a thin electrolyte film. 20,25 The model predicted by Raistrick shows three semi-circles in the spectrum attributed to the charge-transfer process (ORR); agglomerate diffusion (depletion of the oxygen concentration in the pores...

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mentioning

confidence: 99%

Electrochemical Impedance Spectroscopy of Oxygen Reduction Reaction (ORR) in a Rotating Disk Electrode Configuration: Effect of Ionomer Content and Carbon-Support

Singh

Devivaraprasad

Kar

et al. 2015

J. Electrochem. Soc.

159

112

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“…Non-noble metal catalysts based on chalcogenides [36][37][38][39] and macrocycles of transition metals [40][41][42][43][44] have shown good activity for the ORR. However these materials did not yet match the catalytic activity of dispersed platinum.…”

Section: Ii2 New Preparation Methods Of Efficient Electrode Catalystsmentioning

confidence: 99%

Do not forget the electrochemical characteristics of the membrane electrode assembly when designing a Proton Exchange Membrane Fuel Cell stack

Lamy

Jones

Coutanceau

et al. 2011

Electrochimica Acta

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International audienceThe membrane electrode assembly (MEA) is the key component of a PEMFC stack. Conventional MEAs are composed of catalyzed electrodes loaded with 0.1-0.4 mgPt cm−2 pressed against a Nafion® membrane, leading to cell performance close to 0.8 W cm−2 at 0.6 V. Due to their limited stability at high temperatures, the cost of platinum catalysts and that of proton exchange membranes, the recycling problems and material availability, the MEA components do not match the requirements for large scale development of PEMCFs at a low cost, particularly for automotive applications. Novel approaches to medium and high temperature membranes are described in this work, and a composite polybenzimidazole-poly(vinylphosphonic) acid membrane, stable up to 190 ◦C, led to a power density of 0.5 W cm−2 at 160 ◦C under 3 bar abs with hydrogen and air. Concerning the preparation of efficient electrocatalysts supported on a Vulcan XC72 carbon powder, the Bönnemann colloidal method and above all plasma sputtering allowed preparing bimetallic platinum-based electrocatalysts with a low Pt loading. In the case of plasma deposition of Pt nanoclusters, Pt loadings as low as 10 g cm−2 were achieved, leading to a very high mass power density of ca. 20 kW g−1 Pt . Finally characterization of the MEA electrical properties by Electrochemical Impedance Spectroscopy (EIS) based on a theoretical model of mass and charge transport inside the active and gas diffusion layers, together with the optimization of the operating parameters (cell temperature, humidity, flow rate and pressure) allowed obtaining electrical performance greater than 1.2 W cm−2 using an homemade MEA with a rather low Pt loading

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“…It was concluded that the Mo and Ru atoms, in Mo-Ru-Se, were located as independent phases: MoSex, MoOx and RuSex [76]. They, however, showed high selectivity to perform the ORR, in a solution containing methanol, with a four-electron reaction pathway, with an activity nevertheless, lower than that of the standard Pt catalysts in methanol-free electrolyte [77].…”

Section: Transition Metal Chalcogenidesmentioning

confidence: 97%

What Can We Learn in Electrocatalysis, from Nanoparticulated Precious and/or Non-Precious Catalytic Centers Interacting with Their Support?

2016

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This review is devoted to discussing the state of the art in the relevant aspects of the synthesis of novel precious and non-precious electrocatalysts. It covers the production of Pt-and Pd-based electrocatalysts synthesized by the carbonyl chemical route, the synthesis description for the preparation of the most catalytically active transition metal chalcogenides, then the employment of free-surfactants synthesis routes to produce non-precious electrocatalysts. A compilation of the best precious electrocatalysts to perform the hydrogen oxidation reaction (HOR) is described; a section is devoted to the synthesis and electrocatalytic evaluation of non-precious materials which can be used to perform the HOR in alkaline medium. Apropos the oxygen reduction reaction (ORR), the synthesis and modification of the supports is also discussed as well, aiming at describing the state of the art to improve kinetics of low temperature fuel cell reactions via the hybridization process of the catalytic center with a variety of carbon-based, and ceramic-carbon supports. Last, but not least, the review covers the experimental half-cells results in a micro-fuel cell platform obtained in our laboratory, and by other workers, analyzing the history of the first micro-fuel cell systems and their tailoring throughout the time bestowing to the design and operating conditions.

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Oxygen Reduction on Ru[sub 1.92]Mo[sub 0.08]SeO[sub 4], Ru/Carbon, and Pt/Carbon in Pure and Methanol-Containing Electrolytes

Cited by 227 publications

References 20 publications

Electrochemical Impedance Spectroscopy of Oxygen Reduction Reaction (ORR) in a Rotating Disk Electrode Configuration: Effect of Ionomer Content and Carbon-Support

Electrochemical Impedance Spectroscopy of Oxygen Reduction Reaction (ORR) in a Rotating Disk Electrode Configuration: Effect of Ionomer Content and Carbon-Support

Do not forget the electrochemical characteristics of the membrane electrode assembly when designing a Proton Exchange Membrane Fuel Cell stack

What Can We Learn in Electrocatalysis, from Nanoparticulated Precious and/or Non-Precious Catalytic Centers Interacting with Their Support?

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