Preparation and characterisation of platinum on carbon substrates electrocatalysts as electrodes in polymer electrolyte fuel cells.

Gas Diffusion Electrodes (GDE) used in Polymer Electrolyte Fuel Cells (PEFCs) are prepared by catalyst nanoparticles deposition on porous and high surface carbon substrates. These electrocatalysts are traditionally obtained by carbon support impregnation with Pt precursors followed by chemical reduction and heat treatment in hydrogen. By this method, however, it is necessary to deposit high amount of Pt to achieve good performances and Pt nanoparticles localisation in reaction sites is critical. In this work we describe a new electrodeposition method: in fact, applying an electric field to deposit Pt nanoparticles on glassy carbon (GC), on carbon powder (CP) and on carbon nanotubes (CNTs), previous problems are nearly resolved1. A solution containing H2PtCl6 (ECPA) 5mM in 1M H2SO4 at 30°C is used for galvanostatic electrodeposition at constant (GED) and pulsed current (PED)2. Chemical analysis, cyclic voltammetry (CV) and FEG-SEM technique are used to determine electrochemical characteristics of Pt deposit and the influence of electrodeposition method on the nano-morphology. Electrocatalytic performances were carried out by oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) in H2SO4, re-calculating data in the form of mass specific activity (MSA) and surface specific activity (SSA) to take in account the real electrochemical surface of Pt loading3. A comparison with commercial Pt/C catalysts shows an higher activity, at lower Pt loading, for our materials. 1L.Giorgi, E.Simonetti, F.Cardellini and R.Yamamoto, 4th International Conference on Electrocatalysis, September 22-25, 2002, Como (Italy) 2G.Papa, Thesis, University of Rome, 2003 3L.Giorgi, G.Papa, E.Simonetti, L.Pilloni, 7th International Conference on Nanostructured Materials, June 20-24, 2004, Wiesbaden (Germany)