title: Enhancement in Kinetics of the Oxygen Reduction Reaction on a Nitrogen-Doped Carbon Catalyst by Introduction of Iron via Electrochemical Methods.
abstract: The iron (Fe) electrodeposition-electrochemical dissolution has been employed on nitrogen-doped carbon material (P-PI) prepared via multi-step pyrolysis of a polyimide precursor to achieve the introduction of Fe species, and its influence on the oxygen reduction reaction (ORR) is investigated by cyclic and rotating ring-disk electrode voltammetry in 0.5 M H2SO4. After the electrochemical treatment, the overpotential and H2O2 production percentage of ORR on the P-PI are decreased and the number of electrons transferred is increased in the meanwhile. In combination with the results of X-ray absorption fine structure spectra, the presence of Fe-Nx sites (Fe ions coordinated by nitrogen) is believed to be responsible for the improved ORR performance. Further kinetic analysis indicates that a two-electron reduction of O2 is predominant on the untreated P-PI with coexistence of a direct four-electron transformation of O2 to H2O, while the introduction of Fe species leads to a larger increase in the rate constant for the four-electron reduction than that for the two-electron process, being in good agreement with the view that Fe-Nx sites are active for four-electron ORR.
authors.affiliation: †Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, Kanagawa 226-8502, Japan.|‡Key Laboratory of Marine Environmental Corrosion and Biofouling, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao, Shandong 266071, People's Republic of China.
authors.forename: Jiajia
authors.initials: J
authors.lastname: Wu
authors.affiliation: †Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, Kanagawa 226-8502, Japan.|§School of Environmental and Materials Engineering, Shanghai Second Polytechnic University, Jinhai Road 2360, Pudong New Area, Shanghai 201209, People's Republic of China.
authors.forename: Da
authors.initials: D
authors.lastname: Zhang
authors.affiliation: ∥Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Chiba 277-8581, Japan.|⊥Synchrotron Radiation Research Organization, University of Tokyo, Sayo-cho, Hyogo 679-5198, Japan.
authors.forename: Hideharu
authors.initials: H
authors.lastname: Niwa
authors.affiliation: ∥Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Chiba 277-8581, Japan.|⊥Synchrotron Radiation Research Organization, University of Tokyo, Sayo-cho, Hyogo 679-5198, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Harada
authors.affiliation: ⊥Synchrotron Radiation Research Organization, University of Tokyo, Sayo-cho, Hyogo 679-5198, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Oshima
authors.affiliation: #Japan Synchrotron Radiation Research Institute, Sayo-cho, Hyogo 679-5198, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Ofuchi
authors.affiliation: ¶Department of Organic and Polymeric Materials, Graduate School of Science and Engineering, Tokyo Institute of Technology, Ookayama, Tokyo 152-8552, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Nabae
authors.affiliation: †Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, Kanagawa 226-8502, Japan.
authors.forename: Takeyoshi
authors.initials: T
authors.lastname: Okajima
authors.affiliation: †Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, Kanagawa 226-8502, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Ohsaka