# IrO2–SnO2 mixtures as electrocatalysts for the oxygen reduction reaction in alkaline media

Authors
• 1 Università degli Studi di Milano, Dipartimento di Chimica, Via Golgi 19, Milan, 20133, Italy , Milan (Italy)
Type
Published Article
Journal
Journal of Applied Electrochemistry
Publisher
Springer Netherlands
Publication Date
Jan 04, 2013
Volume
43
Issue
2
Pages
171–179
Identifiers
DOI: 10.1007/s10800-012-0520-3
Source
Springer Nature
Keywords
License
Yellow

## Abstract

In this work, SnO2 + IrO2 mixed oxides are studied as electrocatalysts for the oxygen reduction reaction (ORR) in alkaline media by means of voltammetric techniques under controlled mass transfer conditions thanks to the use of rotating (ring) disk electrodes (RDE/RRDE). The oxides, prepared by sol–gel methodology, are supported on the disk electrodes using a thin layer of anionic exchange polymer as gluing agent. The amount of deposited polymer was optimized to avoid any limitation due to the diffusion of reactant/products across the film thickness. The mixed oxides were prepared at the following mole fractions of IrO2: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$x_{{{\text{IrO}}_{ 2} }}$$\end{document} = 0.15, 0.31, 0.55, 0.73, and 1. The role of composition was studied in terms of the reaction pathways and the relevant fraction of H2O2 production, together with the potentials of the onset of ORR. The fraction of sites able to give proton/hydroxyl and electron transfers is also determined and discussed. The results point to the best performance of low-Ir containing mixtures and to their low sensitivity to the presence of methanol, a key feature in the case of crossover in alkaline direct alcohol fuel cells.

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