Sb or Nb doped tin dioxide aerogels as catalytic support for PEMFC cathode
Résumé
Carbon blacks supported Pt are currently widely used as electrocatalysts in Proton exchange Membrane Fuel Cells (PEMFC). However they are thermochemically unstable in PEMFC operating conditions (acidic media, T = 80°C, high potential and relative humidity), especially at the cathode side. Because of carbon oxidation PEMFC performance decrease with time and long term durability need to be improved in order to consider PEMFC as credible alternatives to conventional power sources for automotive, stationary and portable application. In order to solve this technological issue, a stable metal oxide, namely tin dioxide, has been studied to replace carbon black as a catalyst support. SnO2 is a well-known n-type semi-conductor with a relatively high electrical conductivity, which can be improved by doping with hypervalent components, such as Nb5+ or Sb5+. In addition this new catalyst support material must develop a high specific surface area with a mesoporous morphology to allow good dispersion and activity of the catalyst (Pt). Aerogels have already proven their ability to efficiently support catalyst for PEMFC application [1, 2]. So Nb or Sb doped SnO2 aerogels were synthetized by sol-gel route, from commercial and homemade alkoxide precursors, followed by supercritical CO2 drying. After calcination in air, the resulting mesoporous material shows relatively high specific surface area, good crystallinity and remarkably high conductivity. These obtained properties make SnO2:Sb a promising material as catalyst support for PEMFC cathode. Platinum deposition will also be presented and our latest results will be discussed with respect to the foreseen application. References : 1. M. Ouattara-Brigaudet, , S. Berthon-Fabry, C. Beauger, M. Chatenet, N. Job, M. Sennour, Influence of the carbon texture of platinum/carbon aerogel electrocatalysts on their behavior in a proton exchange membrane fuel cell cathode. International Journal of Hydrogen Energy 37, 9742-9757 (2012). 2. M. Ouattara-Brigaudet, C. Beauger, S. Berthon-Fabry, P. Achard, Carbon Aerogels as Catalyst Supports and First Insights on Their Durability in Proton Exchange Membrane Fuel Cells. Fuel Cells 11, 726-734 (2011).