A Systematic Investigation of Carbon Pretreatment for the Synthesis of Platinum Nano-Catalysts for Oxygen Reduction Reaction

Abstract

The synthesis of electrocatalysts for low- and high temperature fuel cells is dependent on many different factors that determine the activity of the produced catalysts. One important and highly underrepresented factor in literature are carbon pretreatments, which have a strong impact on the electrochemical activity of the produced catalyst. A web of science search showed that less than 1% of the articles working with the synthesis of Pt-based catalysts for the Oxygen reduction reaction (ORR) contain information on carbon pretreatments. In recent years no articles on the topic of carbon pretreatment for the synthesis of Pt-based ORR catalyst have been published.However, different forms (as powder, nano tubes, etc.) of carbon are commonly used as support material for Pt-based catalysts. Previous work has shown the importance of pretreatment of carbon supports to change the surface-active groups, enhancing the dispersion and reducing agglomeration of Pt-nanoparticles [1]. Oxidizing treatments are known to change the surface groups and decreasing the BET surface area [2]. Furthermore, carbon pretreatments can effectively reduce impurities present in as-purchased carbon [3].A systematic study of pretreatments of Vulcan XC72-R and Ketjen 300 have been carried out followed by the synthesis of supported Pt-nanoparticles using XPS, XRD, TEM, BET and RDE techniques. We found that the presence of sulfur in the surface strongly correlates with the ECSA of the supported Pt catalyst. This talk will elaborate on the effect of pretreatments on the carbon support, the synthesis of Pt nanoparticles and its impact on the resulting electrochemical performance: Compared to as received carbon, the Pt mass activity could be increased by a factor 4, exceeding the mass activity of comparable commercial Pt/C electrocatalysts.[1] Bimetallic Pt–Sn catalysts supported on activated carbon I. The effects of support modification and impregnation strategy - A. Erhan Aksoylu; M. Madalena A. Freitas; Jose L. Figueiredo[2] The effect of pretreatment of Vulcan XC-72R carbon on morphology and electrochemical oxygen reduction kinetics of supported Pd nano-particle in acidic electrolyte - Senthil Kumar, S. M.; Soler Herrero, Jaime; Irusta, Silvia; Scott, Keith[3] Effect of the carbon pre-treatment on the properties and performance for nitrobenzene hydrogenation of Pt/C catalysts - Torres, G. C.; Jablonski, E. L.; Baronetti, G. T.; Castro, A. A.; De Miguel, S. R.; Scelza, O. A.; Blanco, M. D.; Peña Jiménez, M. A.; Fierro, J. L.G. Figure 1