The polymer electrolyte fuel cells (PEFCs) have high potentiality for the use in electrical vehicles, electric power production and portable electronic power application due to their good energy conversion efficiency and high power density of their fuel sources1. To make PEFCs commercial reality, much development work has focused on the performance improvement of electrode materials and electrocatalysts2. The PEFCs gas diffusion electrodes (GDE) are catalysed by deposition of Pt nanoparticles on carbon powder. Such particles must be localized on the elecrode surface to achieve high electrocatalyst utilization. The traditional techniques for the electrocatalyst deposition (impregnation followed chemical reduction of metal precursors) don’t allow a surface localization and therefore it is necessary to deposit high quantity of Pt. One important thrust of present research is lowering overall fuel cell cost through several approaches, such as reducing electrocatalyst loadings or simplifying the cell design and manufacturing process. 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 two different preparation methods of Pt electrocatalyst on carbon powder e carbon nanotubes. The Pt film were deposited on gas diffusion electrode (GDE) substrates using a commercial RF magnetron sputtering system. By varyng the deposition time we deposited Pt with three different equivalent film thickness (1,3,6 nm). The electrochemical deposition process was carried out in a solution containing H2PtCl6 5 mM in 1M of H2SO4, at 30oC with a galvanostatic electrodeposition at constant (GED) and pulsed (PED) current. Platinum deposit was characterized by chemical analysis, cyclic voltammetry (CV) and FEGSEM in order to determine the electrochemical real surface (ERS) and the influence of deposition techniques on the nano-morfology. The electrocatalytic performance was evaluated by means of methanol oxidation reaction (MOR) in H2SO4. The data were presented in the form of surface specific activity (SSA) and mass specific activity (MSA) to take into account ERS and platinum loading. A comparison with commercial Pt/C catalysts shows an higher activity, at lower Pt loading, for our materials. 1Srivasan, S. J. Electrochem. Soc. 1989, 41C, 136 2Giorgi, L.; Papa, G.; Simonetti, E.; Pilloni, L.; 7th International Conference on Nanostructured Materials, June 20-24, 2004, Wiesbaden (Germany)
Deposition of nanostructered electrocatalysts by PVD and electrodeposition on carbon powder and carbon nanotubes / Pasquali, Mauro; Paoletti, C.; Giorgi, L.; Pilloni, L.; Giorgi, R.; Serra, E.; Colalillom, ; Cemmi, A.; Alvisi, M. AND GALTIERI G.. - (2005).
Deposition of nanostructered electrocatalysts by PVD and electrodeposition on carbon powder and carbon nanotubes
PASQUALI, Mauro;
2005
Abstract
The polymer electrolyte fuel cells (PEFCs) have high potentiality for the use in electrical vehicles, electric power production and portable electronic power application due to their good energy conversion efficiency and high power density of their fuel sources1. To make PEFCs commercial reality, much development work has focused on the performance improvement of electrode materials and electrocatalysts2. The PEFCs gas diffusion electrodes (GDE) are catalysed by deposition of Pt nanoparticles on carbon powder. Such particles must be localized on the elecrode surface to achieve high electrocatalyst utilization. The traditional techniques for the electrocatalyst deposition (impregnation followed chemical reduction of metal precursors) don’t allow a surface localization and therefore it is necessary to deposit high quantity of Pt. One important thrust of present research is lowering overall fuel cell cost through several approaches, such as reducing electrocatalyst loadings or simplifying the cell design and manufacturing process. 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 two different preparation methods of Pt electrocatalyst on carbon powder e carbon nanotubes. The Pt film were deposited on gas diffusion electrode (GDE) substrates using a commercial RF magnetron sputtering system. By varyng the deposition time we deposited Pt with three different equivalent film thickness (1,3,6 nm). The electrochemical deposition process was carried out in a solution containing H2PtCl6 5 mM in 1M of H2SO4, at 30oC with a galvanostatic electrodeposition at constant (GED) and pulsed (PED) current. Platinum deposit was characterized by chemical analysis, cyclic voltammetry (CV) and FEGSEM in order to determine the electrochemical real surface (ERS) and the influence of deposition techniques on the nano-morfology. The electrocatalytic performance was evaluated by means of methanol oxidation reaction (MOR) in H2SO4. The data were presented in the form of surface specific activity (SSA) and mass specific activity (MSA) to take into account ERS and platinum loading. A comparison with commercial Pt/C catalysts shows an higher activity, at lower Pt loading, for our materials. 1Srivasan, S. J. Electrochem. Soc. 1989, 41C, 136 2Giorgi, L.; Papa, G.; Simonetti, E.; Pilloni, L.; 7th International Conference on Nanostructured Materials, June 20-24, 2004, Wiesbaden (Germany)I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
