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Laboratoire d'Electrochimie Moleculaire, LEM, Paris

UMR CNRS - Université Paris Diderot - Paris France

   
 
Master Frontiers in Chemistry | UFR de Chimie - Université Paris Diderot - Paris 7 CNRS - Institut de chimie Université de Paris Master Chimie Sorbonne Paris Cité UFR de Chimie - Université Paris Diderot - Paris 7 CNRS - Institut de chimie
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Université Paris Diderot
Université de Paris CNRS, Centre National de la Recherche Scientifique
 
 


Le LEM - Publications: Abstracts

Publication 805

J. Phys. Chem. C, 120 (38) 21263-21271, 2016
DOI:10.1021/acs.jpcc.6b07013
   
doi

Conductive mesoporous catalytic films. Current distortion and performance degradation by dual-phase ohmic drop effects. Analysis and remedies

Claude P. Andrieux, Cyrille Costentin, Carlo Di Giovanni, Jean-Michel Savéant, and Cédric Tard

Université Paris Diderot, Sorbonne Paris Cité, Laboratoire d’Electrochimie Moléculaire, Unité Mixte de Recherche Université - CNRS No. 7591, Bâtiment Lavoisier, 15 rue Jean de Baïf, 75205 Cedex 13 Paris, France

In the active interest aroused by catalysis of electrochemical reactions, particularly molecule activation related to modern energy challenges, mesoporous films deposited on electrodes are often preferred to catalysts homogeneously dispersed in solution. Conduction in the solid portion of the film and in the pores may strongly affect the characteristic catalytic Tafel plots, possibly leading to mechanistic misinterpretation and also degrade the catalytic performances. These ohmic drop effects take place, unlike those classically encountered with a massive electrode immersed in an electrolytic solution, in two different zones of the film, the solid bulk of the film and the pores, that are coupled together by a distributed capacitance and by the faradaic impedance representing the catalytic reaction located at their interface. A transmission line modeling allows the analysis of the capacitance charging responses as a function of only two dimensionless parameters in the framework of linear scan voltammetry: the ratio of the resistances in the two parts of the film and of the time-constant of the film. After validation with an experimental system consisting of an ionic polymer/carbon powder mixture, deposited on a glassy carbon electrode and immersed in a strong electrolyte aqueous solution, a procedure is established that gives access the key-conduction parameters of the film. On these bases, and of the predicted current–potential responses for fast catalytic reactions according to the same transition line model, it is shown how the dual-phase ohmic drop effects can be gauged and compensated. Ensuing consequences on optimization of macroelectrolysis are finally discussed.

 
   
 
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