title: The particle size effect on the oxygen reduction reaction activity of Pt catalysts: influence of electrolyte and relation to single crystal models.
abstract: The influence of particle size on the oxygen reduction reaction (ORR) activity of Pt was examined in three different electrolytes: two acidic solutions, with varying anionic adsorption strength (HClO(4) < H(2)SO(4)); and an alkaline solution (KOH). The experiments show that the absolute ORR rate is dependent on the supporting electrolyte; however, the relationship between activity and particle size is rather independent of the supporting electrolyte. The specific activity (SA) toward the ORR rapidly decreases in the order of polycrystalline Pt > unsupported Pt black particles (~30 nm) > high surface area (HSA) carbon supported Pt nanoparticle catalysts (of various size between 1 and 5 nm). In contrast to previous work, it is highlighted that the difference in SA between the individual HSA carbon supported catalysts (1 to 5 nm) is rather trivial and that the main challenge is to understand the significant differences in SA between the polycrystalline Pt, unsupported Pt particles, and HSA carbon supported Pt catalysts. Finally, a comparison between measured and modeled activities (based on the distribution of surface planes and their SAs) for different particle sizes indicates that such simple models do not capture all aspects of the behavior of HSA carbon supported catalysts.
authors.affiliation: Department of Chemistry, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Markus
authors.initials: M
authors.lastname: Nesselberger
authors.forename: Sean
authors.initials: S
authors.lastname: Ashton
authors.forename: Josef C
authors.initials: JC
authors.lastname: Meier
authors.forename: Ioannis
authors.initials: I
authors.lastname: Katsounaros
authors.forename: Karl J J
authors.initials: KJ
authors.lastname: Mayrhofer
authors.forename: Matthias
authors.initials: M
authors.lastname: Arenz
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D004573:Electrolytes / Q000737:chemistry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010316:Particle Size; D010984:Platinum / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D010984:Platinum; D010100:Oxygen