An improved method for the determination of the electrochemical active area of porous composite platinum electrodes

In this project, an improved method for determining the electrochemical act ive area (ECA) of a platinum electrocatalyst has been developed. By the use of cyclic voltammetry, the ECA of a platinum electrocatalyst is measured b y hydrogen adsorption. In the procedure, the charge used to form one monola yer of hydrogen is measured. The determination is influenced by the hydroge n evolution reaction and an accurate procedure is needed. Therefore, the hy drogen adsorption is modelled by three Frumkin-like adsorption isotherms. B y performing a simulation of the measured cyclic voltammetry curves in the hydrogen adsorption potential region (hydride region), it has been possible to obtain a very accurate measure for the electrochemical active area. In this way, the current originating from the hydrogen evolution reaction can be sorted out. The procedure is used to characterise two different oxygen r eduction electrodes both prepared from the same Pt/C catalyst with Nafion(( R)) as binder. (C) 2001 Elsevier Science B.V. All rights reserved.