Platinum catalyst nanowires – electrochemical development and performances

SIBIUDE, F. GALDRIC; NORES PONDAL, FEDERICO J.; GUILLET, NICOLAS; BIDAN, GÉRARD; AL-HOSHAN, MANSOUR

Grenoble

Conferencia; Fundamentals and Developments of Fuel Cells Conference 2011; 2011

CNRS, CEA y el laboratorio LEPMI, de Francia.

Platinum catalyst nanowires – electrochemical development and performances F. G. SIBIUDEa, F. J. NORES-PONDALa, N. GUILLETa, G. BIDANb, M. ALHOSHANc Commissariat à l’Energie Atomique et aux Energies alternatives a CEA-Grenoble/DRT/LITEN/DEHT/LCPEM                                b CEA-Grenoble/INAC 17, Rue des Martyrs - 38054 Grenoble Cedex 9 (France) c King Saud University, chemical engineering dpt, College of engineering PO Box 800, Riyadh 11421, Kingdom of Saudi Arabia PO Box 800, Riyadh 11421, Kingdom of Saudi Arabia galdric.sibiude@cea.fr Keywords: Fuel Cells, Nanostructuration, Nanowires, Electrodeposition, Catalysts, Platinum. Decreasing the platinum loading is one of the required conditions to make PEMFC economically viable. Nanostructuration of particle greatly enhance the mass catalytic activity by increasin the surface area. For this reason, nanostructuration presents a growing interest to improve the yield in fuel cells and decrease the amount of precious metals.  Platinum nanowires directly grown on porous and conductive substrate are of prime interest since the deposit can simply be used as an electrode, allowing gases and water flows, without any post-treatment. A templated electrodeposition way of making this kind of structure will be exposed and the first physical growth phenomenon understandings will be discussed. The process offers new and practical possibilities in fuel cell application compared with the classical template electrodeposition on thin films [1]. Nanowires are expected to show good catalytic performance [2] as well as good durability. At the moment, the use of such a structure gives promising performances towards oxygen reduction reaction (j(0,9V) = -150µAcmPt-2 at 25°C similar to Pt nanoparticles [3]) with low loading but needs to be further explored. However, this easy process allows us to quickly transfer the deposit in half-cell or fuel cell test by pressing it on a polymer electrolyte membrane. Studies have been performed to investigate the influence of the different electrodeposition parameters. Particularly, the reaction yield versus deposition potential has been analysed for a constant charge. Proceeding by fixing the charge allows us to get a better control of the deposited quantity, considering the yield.  A prime problem to solve is the presence of free volumes at the matrix/microporous interface that have to be filled in. To do so, we are exploring the use of support materials for platinum catalysts that could be used to fill in those free volumes such as classic metals as well as innovative materials (conducting polymers).  The main objective is now to increase the electroactive surface area of platinum by reducing large-volume particles and test this architecture in fuel cell.  The advantage of the process is the possibility to control the pattern of the deposit by controlling the matrix porosity and the electrodeposition parameters. That would potentially lead to a better distribution of the catalyst in active layers by locating it at the good places and a better fluidic diffusion [4]. It will also be extended to the exploration of new catalyst nanowires. [1] S. M. Choi, et al. Electrochimica Acta 53 (19):5804-5811, 2008 [2] M. Subhramannia, et al. Journal of Materials Chemistry 18:5858-5870, 2008 [3] H.A. Gasteiger, et al. Applied Catalysis B: Environmental 56: 9–35, 2005 [4] A.A. Franco, et al. Journal. of the Electrochemical Society 156(3): B410-B424, 2009