title: Pore development in carbonized hemoglobin by concurrently generated MgO template for activity enhancement as fuel cell cathode catalyst.
abstract: Various carbon materials with a characteristic morphology and pore structure have been produced using template methods in which a carbon-template composite is once formed and the characteristic features derived from the template are generated after the template removal. In this study, hemoglobin, which is a natural compound that could be abundantly and inexpensively obtained, was used as the carbon material source to produce a carbonaceous noble-metal-free fuel cell cathode catalyst. Magnesium oxide was used as the template concurrently generated with the hemoglobin carbonization from magnesium acetate mixed with hemoglobin as the starting material mixture to enable pore development for improving the activity of the carbonized hemoglobin for the cathodic oxygen reduction. After removal of the MgO template, the substantially developed pores were generated in the carbonized hemoglobin with an amorphous structure observed by total-electron-yield X-ray absorption. The extended X-ray absorption fine structure at the Fe-K edge indicated that Fe was coordinated with four nitrogen atoms (Fe-N(4) moiety) in the carbonized hemoglobin. The oxygen reduction activity of the carbonized hemoglobin evaluated using rotating disk electrodes was dependent on the pore structure. The highly developed pores led to an improved activity.
authors.affiliation: Environmental Technology Research Division, Osaka Municipal Technical Research Institute, 1-6-50, Morinomiya, Osaka 536-8553, Japan. maruyama@omtri.or.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Maruyama
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Taiji
authors.initials: T
authors.lastname: Amano
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Muramatsu
authors.forename: Eric M
authors.initials: EM
authors.lastname: Gullikson
authors.forename: Yuki
authors.initials: Y
authors.lastname: Orikasa
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Uchimoto
mesh_terms: D001674:Bioelectric Energy Sources; D002384:Catalysis; D004566:Electrodes; D006454:Hemoglobins / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D016062:Porosity
chemical_list: D006454:Hemoglobins; D008277:Magnesium Oxide; D010100:Oxygen