Résumé
Proton exchange membrane fuel cells are promising alternatives to usual power sources for transport, portable and stationary applications. However, the degradation of commercial carbon-supported platinum (Pt/C) nanoparticles is still a major issue. To replace high surface area carbon supports, n-type metal oxide semiconductors could be an option provided that their electrical conductivity can be increased, and that they possess adequate porosity [1-4]. In this study, a range of Nb, Ta and V – doped TiO2 aerogels were synthesized by acid-catalyzed sol-gel synthesis of titanium n-butoxide in isopropanol followed by supercritical drying with carbon dioxide. After calcination under hydrogen at 800 °C, the resulting doped TiO2 aerogels feature specific surface area up to 65 m2/gTiO2 with a porosity mostly centered on 18-25 nm for 10 at.% of Nb, Ta and V. Two deposition methods (impregnation/photo-reduction and microwave-assisted polyol synthesis [4]) were used to deposit platinum nanoparticles onto the doped TiO2 aerogels. The morphology of the synthesized materials was characterized by nitrogen sorption, X-ray diffraction and scanning electron microscopy. Their chemical structure was determined by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The electrical conductivity of Nb, Ta and V – doped TiO2 materials was determined by impedance spectroscopy. Finally, the surface reactivity and the electrocatalytic activity of the synthesized materials for the oxygen reduction reaction were determined in liquid and solid electrolyte. The research leading to these results has received funding from the French National Research Agency (ANR-12-PRGE-0007/SURICAT project). References : 1. J. Marie, S. Berthon-Fabry, M. Chatenet, E. Chainet, R. Pirard, N. Cornet and P. Achard., 2007, Journal of Applied Electrochemistry, vol. 37, pp. 147-153. 2. M. Ouattara-Brigaudet, C. Beauger, S. Berthon-Fabry, P. Achard., 2011, Fuel Cells, vol. 11, pp.726-734. 3. M. Ouattara-Brigaudet, S. Berthon-Fabry, C. Beauger, M. Chatenet, N. Job, M. Sennour., 2012, International Journal of Hydrogen Energy, vol. 37, pp. 9742-9757. 4. I. Savych, J. Bernard d’Arbigny, S. Subianto, S. Cavaliere, D.J. Jones, J. Rozière., 2014, J. Power Sources, vol. 257, pp. 147-155