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

Hiraike Y, Saito M, Niwa H, Kobayashi M, Harada Y, Oshima M, Kim J, Nabae Y, Kakimoto MA - Nanoscale Res Lett (2015)

Bottom Line: 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.Consequently, effective doping of active nitrogen species into the sp (2) carbon network of the HB-FePc catalysts may occur up to 900°C.

View Article: PubMed Central - PubMed

Affiliation: 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.

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.

No MeSH data available.


Structural formulae of precursors. (a) Iron phthalocyanine (FePc) and phenolic resin (PhRs), and (b) hyperbranched iron phthalocyanine polymer (HB-FePc). In this study, biphenyl was used to link HB-FePc (X).
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Fig1: Structural formulae of precursors. (a) Iron phthalocyanine (FePc) and phenolic resin (PhRs), and (b) hyperbranched iron phthalocyanine polymer (HB-FePc). In this study, biphenyl was used to link HB-FePc (X).

Mentions: Two different types of carbon-based cathode catalysts were prepared from pyrolysis of (i) a mixture of FePc/PhRs and (ii) HB-FePc with a specific linker (see Figure 1). The Fe content of the HB-FePc precursor was in the range of 2.2 to 2.7 wt% (estimated from thermogravimetry-differential thermal analysis (TG-DTA) measurements), while that of FePc/PhRs was adjusted to 3 wt%. The carbon-based cathode catalysts were synthesized at various temperatures (500°C to 900°C) under N2 flow for 5 h. These samples are denoted according to their pyrolysis temperature. For example, Fe600 and HB600 denote FePc/PhRs- and HB-FePc-derived carbon-based cathode catalysts pyrolyzed at 600°C, respectively. A mixture of FePc and PhRs that was not heat treated is denoted FePc/PhRs.Figure 1


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

Hiraike Y, Saito M, Niwa H, Kobayashi M, Harada Y, Oshima M, Kim J, Nabae Y, Kakimoto MA - Nanoscale Res Lett (2015)

Structural formulae of precursors. (a) Iron phthalocyanine (FePc) and phenolic resin (PhRs), and (b) hyperbranched iron phthalocyanine polymer (HB-FePc). In this study, biphenyl was used to link HB-FePc (X).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401482&req=5

Fig1: Structural formulae of precursors. (a) Iron phthalocyanine (FePc) and phenolic resin (PhRs), and (b) hyperbranched iron phthalocyanine polymer (HB-FePc). In this study, biphenyl was used to link HB-FePc (X).
Mentions: Two different types of carbon-based cathode catalysts were prepared from pyrolysis of (i) a mixture of FePc/PhRs and (ii) HB-FePc with a specific linker (see Figure 1). The Fe content of the HB-FePc precursor was in the range of 2.2 to 2.7 wt% (estimated from thermogravimetry-differential thermal analysis (TG-DTA) measurements), while that of FePc/PhRs was adjusted to 3 wt%. The carbon-based cathode catalysts were synthesized at various temperatures (500°C to 900°C) under N2 flow for 5 h. These samples are denoted according to their pyrolysis temperature. For example, Fe600 and HB600 denote FePc/PhRs- and HB-FePc-derived carbon-based cathode catalysts pyrolyzed at 600°C, respectively. A mixture of FePc and PhRs that was not heat treated is denoted FePc/PhRs.Figure 1

Bottom Line: 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.Consequently, effective doping of active nitrogen species into the sp (2) carbon network of the HB-FePc catalysts may occur up to 900°C.

View Article: PubMed Central - PubMed

Affiliation: 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.

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.

No MeSH data available.