12 may 2015 - LMGP Séminar : Gwenn Cognard - Using metal oxides as catalyst support in Proton Exchange Membrane Fuel Cells

PhD student, Cognard – Gwenn  -LEPMI (Laboratoire d'Electrochimie et de Physicochimie des Matériaux et des Interfaces)
Supervisors: Maillard Frédéric – Chatenet Marian (LEPMI)
Collaborator: Riassetto David (LMGP)

Abstract

Proton Exchange Membrane Fuel Cells (PEMFC) are eco-friendly and efficient energy converters, the power range of which allow their utilization in mobile, transport and stationary applications. Nevertheless their large-scale development requires further improvements, specifically regarding their lifetime, which is essentially related to their constitutive materials. The state-of-the-art electrocatalysts used to catalyse the electrochemical reactions are composed of platinum nanoparticles supported on a high surface area carbon. The corrosion of the carbon support is a concern at the cathode, in particular during start/stop or fuel starvation events, where the electrode potential may reach up to 1.5 V vs. the normal hydrogen electrode (NHE).

To tackle this problem, carbon-free catalyst supports based on metal oxides are currently developed at LEPMI. These supports must fulfil at least 3 essential criteria to be compatible with the PEMFC technology: (i) be electron-conducting, (ii) possess a texture compatible with the synthesis of high-surface area electrocatalysts and with the elaboration of PEMFC electrodes, and (iii) be corrosion-resistant in PEMFC operating conditions.

Two oxides have been selected on the basis of promising preliminary works: titanium dioxide (TiO₂) and tin dioxide (SnO₂). Their electronic conductivity is increased by doping (Nb or Sb) and different synthesis routes are implemented to obtain various morphologies (nanofibers, nanotubes, aerogels). Platinum nanoparticles are deposited on these supports via colloidal methods (impregnation/photochemical reduction, polyol synthesis). The catalytic performance of the synthesized catalysts is tested towards the oxygen reduction reaction (ORR), and compared to that of a benchmark Pt/C electrocatalyst. The mechanisms of degradation of the synthesized and the reference electrocatalysts are investigated with the help of accelerated stress tests.

This project is funded by the French National Research Agency (ANR-12-670 PRGE-0007-01 – SURICAT project: Robust and Innovative Metal Oxide Supports for PEMFC Electrocatalysis).