Poster De Conférence Année : 2011

Electrografting of Pyridine for Electrochemical Applications

Résumé

The modification of surface by reduction of diazonium salts has attracted a lot of interest in the past decade. This method, developed by Pinson et al.1, is very attractive because several molecules can be used to form a covalent bond between aryl groups bearing a desired functionality and different substrates. In a recent study, it has been shown that a covalent bond between glassy carbon and pyridine could be obtained by electroreduction of an diazonium salt2. The aim of the present work is to investigate the electrografting of pyridine from the corresponding diazonium and the electrochemical behaviour of the grafted pyridine. In this work, a covalent bond between glassy carbon and pyridine was obtained in two steps. Firstly, the diazonium cations were synthesized in the electrochemical cell by reaction of 3-aminopyridine with NaNO2 in aqueous HCl3. Secondly, glassy carbon electrodes were modified by electrochemical reduction of the in situ generated 3-aminopyridinium cations under several conditions. The effect of the glassy carbon electrode modification conditions like diazonium cations concentration and diazotization reaction time, grafting time and potential of potentiostatic reduction were investigated. The resulting modified electrodes were characterized by cyclic voltammetry experiments, carried out in a 5 mM Fe(CN)63-/4- aqueous solution. This method has been used to confirm and to determine the barrier properties of the deposited layers and estimate the pKa of the immobilized pyridine. X-ray photoelectron spectroscopy (XPS) was used to evaluate the atomic concentration of the species present at the glassy carbon electrode surface. Cyclic voltammetry experiments showed that the blocking effect of the grafted layer increases as the applied potential is made more negative and as well with an increase of the reduction time. It is possible to obtain a relative control of the layer thickness by changing the applied potential and the grafting time. The evolution of the peak current as a function of the solution pH for the electrochemically modified electrodes in the solution containing Fe(CN)63-/4- as redox probes was investigated. Analyses revealed that the apparent pKa of the immobilized pyridine could be estimated at 5.3. Finally, the electrochemical behaviour of the pyridine-modified electrode will be discussed. (1) Delamar, M.; Hitmi, R.; Pinson, J.; Savéant, J. M. Journal of the American Chemical Society 1992, 114, 5883. (2) Yeşildaǧ, A.; Ekinci, D. Electrochimica Acta 2010, 55, 7000. (3) Baranton, S.; Bélanger, D. Journal of Physical Chemistry B 2005, 109, 24401.

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Dates et versions

hal-04601427 , version 1 (14-10-2024)

Identifiants

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Julia Agullo, Mario Morin, Daniel Bélanger. Electrografting of Pyridine for Electrochemical Applications. Elecnano4 - 7th ECHEMS, 2011, Paris, France. ⟨10.1149/1.3652841⟩. ⟨hal-04601427⟩
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