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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 829

ACS Catal., 7, 4876-4880, 2017
DOI:10.1021/acscatal.7b01529
   


doi

Catalysis of Electrochemical Reactions by Surface-Active Sites: Analyzing the Occurrence and Significance of Volcano Plots by Cyclic Voltammetry

 

Cyrille Costentin, and Jean-Michel Savéant

Sorbonne Paris Cité, Laboratoire d’Electrochimie Moléculaire, Unité Mixte de Recherche Université−CNRS 7591, Bâtiment Lavoisier, Université Paris Diderot, 15 rue Jean de Baïf, 75205 Paris Cedex 13, France

Cyclic voltammetry (CV) of heterogeneous electrocatalysts offers a convenient means to critically assess the occurrence of “volcano plots” rendered popular by acid reduction on metal electrodes. The equations relevant to Volmer–Heyrovsky-type reactions shows that the adsorption free energy of the surface-bound intermediate is one of the rate-controlling parameters, which, plotted against the exchange current, could lead to a volcano-looking curve if other rate-controlling factors such as the rate ratio of the two successive electron transfer steps would remain constant upon changing electrocatalyst. This is not necessarily the case in practice, thus blurring the occurrence of volcano plots. Therefore, careful recording and analysis of the CV responses should be a preferred strategy, leading additionally to catalytic Tafel plots for rational electrocatalyst benchmarking. The alternative Volmer–Tafel mechanism gives remarkably rise to S-shaped current–potential responses and to a volcano upon plotting the exchange current against the adsorption standard free energy of the primary intermediate. Again, a wealth of kinetic information results from the characteristics of the current–potential responses.

 
   
 
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