Active site formation mechanism of carbon-based oxygen reduction catalysts derived from a hyperbranched iron phthalocyanine polymer

Yusuke Hiraike; Makoto Saito; Hideharu Niwa; Masaki Kobayashi; Yoshihisa Harada; Masaharu Oshima; Jaehong Kim; Yuta Nabae; Masa-Aki Kakimoto

doi:10.1186/s11671-015-0881-8

Active site formation mechanism of carbon-based oxygen reduction catalysts derived from a hyperbranched iron phthalocyanine polymer

Nanoscale Res Lett. 2015 Apr 14:10:179. doi: 10.1186/s11671-015-0881-8. eCollection 2015.

Authors

Yusuke Hiraike¹, Makoto Saito², Hideharu Niwa³, Masaki Kobayashi⁴, Yoshihisa Harada⁵, Masaharu Oshima⁶, Jaehong Kim⁷, Yuta Nabae⁸, Masa-Aki Kakimoto⁸

Affiliations

¹ Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan ; Current address: Toray Industries, Incorporated, Nihonbashi-Muromachi 2-chome, Tokyo, Japan.
² Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan ; Current address: Toyota Motor Corporation, 1200, Mishuku, Susono, Shizuoka, 410-1107 Japan.
³ Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 Japan.
⁴ Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan ; Current address: Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801 Japan.
⁵ Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 Japan ; Synchrotron Radiation Research Organization, The University of Tokyo, SPring-8, 1-1-1, Koto, Sayo-cho, Sayo-gun, Hyogo, 679-5198 Japan.
⁶ Synchrotron Radiation Research Organization, The University of Tokyo, SPring-8, 1-1-1, Koto, Sayo-cho, Sayo-gun, Hyogo, 679-5198 Japan.
⁷ Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo, 152-8552 Japan ; Current address: OLED R&D Center, Samsung Mobile Display Co., Ltd., Yongin, Gyeonggi 446-811 Korea.
⁸ Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo, 152-8552 Japan.

Abstract

Carbon-based cathode catalysts derived from a hyperbranched iron phthalocyanine polymer (HB-FePc) were characterized, and their active-site formation mechanism was studied by synchrotron-based spectroscopy. The properties of the HB-FePc catalyst are compared with those of a catalyst with high oxygen reduction reaction (ORR) activity synthesized from a mixture of iron phthalocyanine and phenolic resin (FePc/PhRs). Electrochemical measurements demonstrate that the HB-FePc catalyst does not lose its ORR activity up to 900°C, whereas that of the FePc/PhRs catalyst decreases above 700°C. Hard X-ray photoemission spectra reveal that the HB-FePc catalysts retain more nitrogen components than the FePc/PhRs catalysts between pyrolysis temperatures of 600°C and 800°C. This is because the linked structure of the HB-FePc precursor has high thermostability against nitrogen desorption. Consequently, effective doping of active nitrogen species into the sp (2) carbon network of the HB-FePc catalysts may occur up to 900°C.

Keywords: Electronic structure; Hyperbranched polymer; Iron phthalocyanine (FePc); Oxygen reduction reaction (ORR); X-ray photoemission spectroscopy.