The polymer electrolyte fuel cells (PEFCs) have high potentiality for their use in electrical vehicles, electric power production and power for consumer electronic. The PEFC's gas diffusion electrodes (GDEs) are catalyzed by deposition of Pt nanoparticles on carbon powder. Such particles must be localized on the electrode surface to achieve high electrocatalyst utilization. The traditional techniques for the electrocatalyst deposition (impregnation followed chemical reduction of metal precursors) do not allow a surface localization and therefore it is necessary to deposit high quantity of Pt. By means of electrodeposition (EDP) and sputter deposition (PVD) it is possible to localize the Pt on the electrode surface. In fact, both techniques ensure catalyst will be located only in regions that have access to electrons and protons, and the catalyst loading will be highly reduced. In this work we describe the preparation methods based on the electrochemical and sputter deposition of low-loading Pt nanoparticles on gas diffusion electrodes, as a tool for manufacturing polymer electrolyte membrane fuel cell (PEFC, DMFC) electrodes with improved performance and catalyst utilization vs. commercial chemical deposited platinum. The electrocatalytic performance were tested for methanol oxidation reaction and compared to a commercial Pt/C catalyst. The activity, with Pt loading < 0.02 mg cm-2. highly increased compared to commercial catalyst. The best electrocatalytic performances for catalysts prepared by electrodeposition (single pulse GED and multi-pulse PED galavnostatic deposition) were obtained with spherical particles without dendrites and a fine nanostructure (2-4 nm) on the surface. In general the electrodeposited Pt catalyst (<0.1 mgPt cm-2) show a better activity for MeOH oxidation than a commercial E-TEK catalyst, also if the last one has a higher Pt loading (0.3 mgPt cm-2). The sputtering of Pt on un-catalyzed gas diffusion electrodes allows a control of the Pt cluster size and a very uniform distribution of nanosized Pt cluster on the carbon particles surface. The Pt loading obtained is much lower than the commercial catalysts, but the electrochemical active surface resulted highly increased. The specific mass activity (MSA) for methanol oxidation reaction showed significant higher activity for MeOH oxidation than a commercial E-TEK catalyst (10% wt Pt/C). Advantages of sputter and electrochemical deposition compared with state of art chemical deposition are: easy preparation of catalyst (absence of reducing and de-flocculating agents, no heat treatment in hydrogen), easy industrial transfer of the process, cost reduction and low Pt loading. It may be worth nothing that both sputter-deposition and electrodeposition are commercial processes for thin film deposition in other industrial applications. These techniques also have the potential for large-scale manufacture of fuel cell electrodes, with uniform and reproducible layers containing low or ultra-low Pt loadings.
|Publication status||Published - 2005|
|Event||1st European Fuel Cell Technology and Applications Conference 2005, EFC2005 - , Italy|
Duration: 1 Jan 2005 → …
|Conference||1st European Fuel Cell Technology and Applications Conference 2005, EFC2005|
|Period||1/1/05 → …|
All Science Journal Classification (ASJC) codes
Giorgi, L. (2005). Electrodeposition and sputter deposition of platinum nanoparticles on gas diffusion electrodes. Paper presented at 1st European Fuel Cell Technology and Applications Conference 2005, EFC2005, Italy.