Understanding the electrocatalytic activity of transition metal nanoparticles for solid oxide cell fuel electrodes

In this work, we utilized the concept of decoupling the electrocatalytic activity from the current conducting phase of solid oxide cell fuel electrodes to investigate the electrochemical performance of three different transition metals, namely Ni, Co, and Fe. It was found that the nickel and cobalt...

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Bibliographic Details
Published in:Electrochimica acta 2019-12, Vol.327, p.135004, Article 135004
Main Authors: Drasbæk, Daniel B., Traulsen, Marie L., Sudireddy, Bhaskar R., Holtappels, Peter
Format: Article
Language:English
Subjects:
Activation energy
Bonding strength
Catalysts
Cobalt
Decoupling
Electrocatalytic activity
Electrochemical analysis
Electrode polarization
Electrodes
Fuel electrodes
Fuels
Harmonic oscillators
Infiltration
Iron
Model for adsorption of species
Nanoparticles
Nickel
Solid oxide cells
Temperature dependence
Transition metals
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Summary:In this work, we utilized the concept of decoupling the electrocatalytic activity from the current conducting phase of solid oxide cell fuel electrodes to investigate the electrochemical performance of three different transition metals, namely Ni, Co, and Fe. It was found that the nickel and cobalt infiltrated cells had comparable performances in both 4% H2O/H2 and 50% H2O/H2. Furthermore, iron nanoparticles were found to be the better electrocatalyst at low pO2 values, however at higher pO2 values the iron infiltration became the inferior catalyst. Investigating the temperature dependence of the polarization resistance in terms of activation energy and pre-exponential factor showed interesting differences between the metal catalysts and a dependence on the gas atmosphere. The results were analyzed by developing a model based on the harmonic oscillator, the model allows for correlating changes in activation energy and pre-exponential factor with kinetic parameters of the electrode reaction. The model indicates that at higher pO2 values, iron nanoparticles experience a surface blockade, i.e. strong bonding of the reactants to the catalytic sites. For the nickel electrocatalyst, an increase in steam content according to the model leads to an increase in the turnover frequency, which is in good agreement with earlier reports in literature. [Display omitted]
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2019.135004