title: Effect of the state of distribution of supported Pt nanoparticles on effective Pt utilization in polymer electrolyte fuel cells.
abstract: In polymer electrolyte fuel cells, it is essential to minimize Pt loading, particularly at the cathode, without serious loss of performance. From this point of view, we will report an advanced concept for the design of high performance catalysts and membrane-electrode assemblies (MEAs): first, the evaluation of Pt particle distributions on both the interior and exterior walls of various types of carbon black (CB) particles used as supports with respect to the "effective surface (ES)"; second, control of both size and location of Pt particles by means of a new preparation method (nanocapsule method); and finally, a new evaluation method for the properties of MEAs based on the Pt utilization (UPt), mass activity (MA), and effectiveness of Pt (EfPt), based on the ES concept. The amounts of Pt catalyst particles located in the CB nanopores were directly evaluated using the transmission electron microscopy, scanning electron microscopy and corresponding three-dimensional images. By use of the nanocapsule method and optimization of the ionomer, increased MA and EfPt values for the MEA were achieved. The improvement in the cathode performance can be attributed to the sharp particle-size distribution for Pt and the highly uniform dispersion on the exterior surface of graphitized carbon black (GCB) supports.
authors.affiliation: Fuel Cell Nanomaterials Center, University of Yamanashi, 6-43 Miyamae, Kofu 400-0021, Japan. uchidam@yamanashi.ac.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Uchida
authors.forename: Young-Chul
authors.initials: YC
authors.lastname: Park
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Kakinuma
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yano
authors.forename: Donald A
authors.initials: DA
authors.lastname: Tryk
authors.forename: Takeo
authors.initials: T
authors.lastname: Kamino
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Uchida
authors.forename: Masahiro
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D011211:Electric Power Supplies; D004573:Electrolytes / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010984:Platinum / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D011108:Polymers; D010984:Platinum