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Communication Dans Un Congrès Année : 2017

Electrocatalytic reactions within confined solution films

Résumé

The pumped-micropipette delivery/substrate collection (pumped-MD/SC) mode of scanning electrochemical microscopy (SECM) was recently presented for studying pitting corrosion processes,1 and electrocatalytic reactions. This is particularly useful when the electroactive species of interest cannot be selectively generated by electrochemical means. The pumped-MD/SC mode of SECM overcomes most of the limitations present in generation-collection modes for studying electrocatalytic reactions, since this can be used regardless the reactant, the nature of the solvent or the solution pH.2 The pumped-MD/SC mode of SECM is based on the use of a jet of solution, which contains the electroactive species of interest, coming out of a micropipette placed in the vicinity of the studied electrocatalyst. The flux of the reactant out the micropipette is controlled by a piston syringe with a controlled release rate between 2 and 500 μL h-1. The solution jet containing the electroactive species of interest strikes perpendicularly to a planar electrode and spreads out radially over that surface, meanwhile the bulk solution remains at rest. This SECM configuration allows to work in confined solution films, since the controlled gap between the micropipette apex and the electrode surface mimics a thin layer flow cell. Moreover, convection conditions at the electrode surface provided by the solution jet allow steady-state mass transfer rates much greater than purely diffusion rates.3 Thus, this approach allows to control the reaction mass transfer rate simply by controlling the injection flow rate and the micropipette-electrode distance. Subsequently, the residence time of reactant/intermediates and/or reaction products within the confined solution film is also controlled. We present experimental results of two different electrocatalytic reactions; oxygen reduction reaction (ORR) and borohydride oxidation reaction (BOR) studied within confined solution films by the pumped-MD/SC mode of SECM. We also present the corresponding Comsol Multiphysics simulations in order to discriminate between electrocatalytic and mass transport effects. References: 1 N. Aouina, F. Balbaud-Celerier, F. Huet, S. Joiret, H. Perrot, F. Rouillard, V. Vivier, Corros. Sci. 2012, 62, 1. 2 J. V. Perales-Rondón, E. Herrero, J. Solla-Gullón, C. M. Sánchez-Sánchez, V. Vivier, J. Electroanal. Chem. 2017 In press. DOI 10.1016/j.jelechem.2016.12.049. 3 J. V. Macpherson, S. Marcar, P. R. Unwin, Anal. Chem. 1994, 66, 2175.

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Chimie
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Dates et versions

hal-04027927 , version 1 (14-03-2023)

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  • HAL Id : hal-04027927 , version 1

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Andrew Wang, Előd L Gyenge, Vincent Vivier, Carlos M Sánchez-Sánchez. Electrocatalytic reactions within confined solution films. 9th SECM 2017, Aug 2017, Varsovie, Poland. ⟨hal-04027927⟩
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