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Non-Faradic Electrochemical Modifciation of Catalytic Activity
Non-Faradic Electrochemical Modification of Catalytic Activity, or the NEMCA effect, is used to describe the enhancement in catalytic activity (up to 9000% higher) and selectivity of a gas exposed electrode on a solid electrolyte cell upon application of a potential. This electrochemical promotion phenomena is well documented and has been observed on various surfaces (Ni, Au, Pt and Pd) supported by O2-, Na+ and proton conducting solid electrolytes. As implied by the name, this phenomena does not follow Faraday's laws of electrolysis. The Faradic efficiency is defined as follows: E = (r-r0)/(I/nF) where r is the catalytic rate at the applied potential and r0 is the rate at open circuit conditions. I is the applied current, F is Faraday's Constant and n is the number of electrons transferred. Absolute efficiencies greater than 1 are said to exhibit the NEMCA effect. This effect is thought to occur by a back-spillover mechanism where ions from the solid electrolyte migrate onto the gas exposed electrode surface.
Additional recommended knowledge
Categories: Electrochemistry | Catalysts
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Non-Faradic_Electrochemical_Modifciation_of_Catalytic_Activity". A list of authors is available in Wikipedia.|