Non-faradaic

Although the term non-Faradaic process has been used for many decades to describe transient electrochemical processes where part of the current is lost in charging-discharging of metal-electrolyte interfaces, in all these cases the Faradaic efficiency, A, is less than 1 (100%). Furthermore such non-Faradaic processes disappear at steady state. Electrochemical promotion (NEMCA) must be very clearly distinguished from such transient non-Faradaic processes for two reasons ... 

The seminal part of this contribution is that there is a non-Faradaic catalysis, that the catalytic reaction of ethylene with oxygen occurs as well and that it depends on the potential difference across the electrode ... 

Despite the surprise caused by the first literature reports of such large non-Faradaic rate enhancements, often accompanied by large variations in product selectivity, in retrospect the existence of the NEMCA effect can be easily rationalized by combination of simple electrochemical and catalytic principles. 

Wagner was first to propose the use of solid electrolytes to measure in situ the thermodynamic activity of oxygen on metal catalysts.17 This led to the technique of solid electrolyte potentiometry.18 Huggins, Mason and Giir were the first to use solid electrolyte cells to carry out electrocatalytic reactions such as NO decomposition.19,20 The use of solid electrolyte cells for chemical cogeneration , that is, for the simultaneous production of electrical power and industrial chemicals, was first demonstrated in 1980.21 The first non-Faradaic enhancement in heterogeneous catalysis was reported in 1981 for the case of ethylene epoxidation on Ag electrodes,2 3 but it was only... 

C.G. Vayenas, S. Bebelis, and S. Neophytides, Non-Faradaic Electrochemical Modification of Catalytic Activity, J. Phys. Chem. 92, 5083-5085 (1988). 

A. Kaloyannis, and C.G. Vayenas, Non-Faradaic electrochemical modification of catalytic activity. 12 Propylene oxidation on Pt, J. Catal. 182, 37-47 (1999). 

T.I. Politova, G.G. Gal vita, V.D. Belyaev, and V.A. Sobyanin, Non-Faradaic catalysis the case of CO oxidation over Ag-Pd electrode in a solid oxide electrolyte cell, Catal. Lett. 44, 75-81 (1997). 

M. Makri, A. Buekenhoudt, J. Luyten, and C.G. Vayenas, Non-Faradaic Electrochemical Modification of the Catalytic Activity of Pt using aCaZr09ln0 03.a Proton Conductor, Ionics 2, 282-288 (1996). 

D. Tsiplakides, S. Neophytides, O. Enea, M.M. Jaksic, and C.G. Vayenas, Non-faradaic Electrochemical Modification of Catalytic Activity (NEMCA) of Pt Black Electrodes Deposited on Nafion 117 Solid Polymer Electrolyte, /. Electrochem. Soc. 144(6), 2072-2088 (1997). 

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