from first principles PP-I-1

OY-V-3Microstructure Effects in Catalysis of Oxygen Reduction Reaction overElectrodeposited Platinum: Influence of Intergrain BoundariesOschepkov A.G. 1,2 , Simonov A.N. 1 , Rudina N.A. 1 , Parmon V.N. 1,21 Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia2 Novosibirsk State University, Novosibirsk, Russiaalexandr.oschepkov@gmail.comStructural defects play important role in catalysis and electrocatalysis. Remarkably highactivity of Pt-based catalysts with high concentration of defects, specifically, of nm-sizedintergrain boundaries (IGB), has been previously reported for some electrooxidationprocesses [1-2]. Among preparation strategies providing high concentration of IGBs in thecatalyst structure, electrodeposition technique is one of the most efficient [1]. Here, we applyelectrodeposition for preparation of a set of model supported Pt catalysts with variedmicrostructure, and study their catalytic properties for the oxygen reduction reaction (ORR).Glassy carbon (GC) electrodes were used as supports for potentiostatic (E D = 0.05-0.40 V vs.reversible hydrogen electrode (RHE)) deposition of Pt from the 0.01 M H 2 PtCl 6 + 0.01 MHCl solution at 25 o C. Kinetics of the ORR was studied using rotating disk electrode method.SEM studies revealed that Pt/GC deposits comprise coarse (40-300 nm) globules composed ofsmall (0.2 V) structure. Specific surface area (S Pt ) ofplatinum was in the range of 4-12 m 2 g -1 (Pt), the highest value being attained at E D = 0.1 V.The surface-weighted ORR activity of the Pt/GC deposits acquired at E D ≥ 0.2 V decreaseswith the increase of S Pt , following the Pt particle size effect for the ORR. Contrariwise, theactivity of the ‘dendrite’ deposit (E D = 0.1 V) with the highest S Pt outnumbers the activity ofall catalysts studied here and that of the Pt catalysts with close S Pt reported in literature. Notethat under employed deposition conditions, the highest concentration of IGBs is attained at E D~ 0.1 V [1]. The observed tendencies suggest that the ORR activity of Pt catalysts can beeffectively tuned by varying their microstructure and defectiveness. Finally, we tested Pt/Ccatalysts prepared by electrodepositing Pt on the conventional Vulcan support at E D = 0.1 V.The work was financed by Russian Federation President Grants for the Leading ScientificSchools (NSh 524.2012.3) and for Young Ph.D. (MK-380.2011.3).References:[1] O.V. Cherstiouk, A.N. Gavrilov, L.M. Plyasova, et al., J. Solid State Electrochem. 12 (2008) 497[2] A.N. Gavrilov, E.R. Savinova, P.A. Simonov, et al., Phys.Chem.Chem.Phys. 9 (2007) 5476111