Electrochemical characterization of Pt/carbon xerogel and Pt/carbon aerogel catalysts: first insights into the influence of the carbon texture on the Pt nanoparticle morphology and catalytic activity
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Platinum catalysts were prepared by impregnation/reduction of two carbon supports with different pore textures: one carbon aerogel and one carbon xerogel. Impregnation with H2PtCl6 was followed by reduction in aqueous phase with NaBH4, filtration, drying and subsequent reduction by H2. The catalysts were characterized by widely used physico-chemical methods (N2 adsorption, transmission electron microscopy, X-ray diffraction and CO chemisorption); from these techniques, no significant difference could be detected between the two samples. Actual Pt surface areas measured by coulometry of the electrochemical COads stripping are comparable for both samples. However, the peak position and charge below each electrooxidation peak points towards different fraction of small/large particles within these two samples. In addition, COads stripping shows that a fraction of the Pt particle surface is not electrochemically active. Pronounced differences observed in the specific activity towards O2 reduction reaction were then explained by structural differences in Pt particles, undetectable by physico-chemical characterization techniques.
KeywordsOxygen Reduction Reaction Carbon Support Electrochemical Characterization Carbon Aerogel Metal Particle Size
N.J. is a postdoctoral researcher of the F.R.S.-FNRS (Belgium). The Belgian authors thank the Fonds de Bay, the Fonds de Recherche Fondamentale Collective, the Ministère de la Région Wallonne and the Interuniversity Attraction Pole (IAP-P6/17) for their financial support, and acknowledge the involvement of their laboratory in the Network of Excellence FAME of the European Union Sixth Framework Program. The French authors thank the Groupement des Écoles des Mines (GEM).
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