The determination of the number of active sites is a key issue in the evaluation of electrode materials for any electrochemical application. Nonetheless, and particularly in the case of powder materials, a commonly accepted method to determine the actual density of active sites is not yet available, mainly because a method to quantify the amount of material under investigation is missing. In this study, we propose the use of the cavity microelectrode (C-ME, i.e. a cylindrical recessed microdisk) of known volume, which enables the study of a known amount of material thus allowing the quantitative evaluation of its properties. The validation of the method implied: (i) the preparation of C-MEs with different radii and depths; (ii) the calibration of the relevant volumes by means of a “standard” powder, whose number of active sites can be easily determined by cyclic voltammetry; and (iii) their use for the quantification of specific parameters that identify the electrochemical properties of mixed IrO2-SnO2 powders. The results evidence that the quantity of charge relative to the number of pseudocapacitance sites and the currents for the oxygen evolution reaction are proportional to the cavity volumes. This strategy allows the direct comparison of different materials for their rapid and accurate screening. In additions, thanks to the small amount of material required for the sample (typically 10-100 ng), the method can be safely listed among the non-destructive techniques.
Quantitative Studies on Electrode Material Properties by Means of the Cavity Microelectrode / C. Locatelli, A. Minguzzi, A. Vertova, P. Cava, S. Rondinini. - In: ANALYTICAL CHEMISTRY. - ISSN 0003-2700. - 83:7(2011 Apr), pp. 2819-2823.
|Titolo:||Quantitative Studies on Electrode Material Properties by Means of the Cavity Microelectrode|
|Parole Chiave:||microelectrodes; electrocatalysis; active area; active sites; cavity-microelectrodes; water oxydation|
|Settore Scientifico Disciplinare:||Settore CHIM/02 - Chimica Fisica|
|Data di pubblicazione:||apr-2011|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1021/ac200286q|
|Appare nelle tipologie:||01 - Articolo su periodico|