Pyrolyzed cobalt phthalocyanine as electrocatalyst for oxygen reduction

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2220748· OSTI ID:6260760

Ladouceur, M; Lalande, G; Guay, D; Dodelet, J P ^[1]; Dignard-Bailey, L ^[2]; Trudeau, M L; Schulz, R ^[3]

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1. INRS-Energie et Materiaux, Varennes, Quebec (Canada)
2. CANMET, Varennes, Quebec (Canada). Lab. de Recherche en Diversification Energetique
3. Inst. de Recherche d'Hydro-Quebec, Varennes, Quebec (Canada). Technologie des Materiaux

Cobalt phthalocyanine (CoPc) adsorbed on carbon black (XC-72) and heat-treated at temperature ranging from 300 to 1,150 C display catalytic activity toward the electroreduction of oxygen in acidic medium (H[sub 2]SO[sub 4],pH 0.5). The best catalysts are obtained for pyrolysis temperatures ranging from 700 to 950 C. X-ray diffraction performed on CoPc/XC-72 pyrolyzed between 700 and 1,150 C reveals the presence of [beta]-Co particles whose average size varies from 9 nm at 700 C to 44 nm at 1,150 C. Co and N bulk elemental analyses have been performed on CoPc/XC-72 heat-treated from 20 to 1,150 C. These show that: (1) there is no loss of Co even after pyrolysis at 1,150 C when the loading is at 2 weight percent (w/o) Co; (2) the bulk N content decreases as the pyrolysis temperatures are increased and the N content reaches the detection limit (0.5 w/o) at pyrolysis temperatures [>=] 1000 C. X-ray photoelectron spectroscopy (XPS) study shows that at 600 C there is a sudden three-fold increase in the surface concentration of Co and N at the surface of the carbon black support. A sublimation-redistribution of the CoPc is proposed. The effect appears to limit the Co loading to approximately 2 w/o (At loadings of 4 and 8 w/o Co, most of the Co is lost due to the sublimation.) The XPS study also shows that metallic Co particles begin to be formed at 600 C, and that the formation and growth of Co particles occurs as the pyrolysis temperature increases to 1,050 C. The chemical stability of the pyrolyzed catalysts was evaluated in concentrated H[sub 2]SO[sub 4],HCl, and HNO[sub 3] for time periods ranging from 1 to 30 min. Bulk Co analysis, after immersion in acid, indicate that up to 40% of the Co can be lost in the process, and that this induces a decrease in the catalyst activity.

• OSTI ID: 6260760
• Journal Information: Journal of the Electrochemical Society; (United States), Vol. 140:7; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COBALT COMPOUNDS
CATALYTIC EFFECTS
PHTHALOCYANINES
SOLID ELECTROLYTE FUEL CELLS
ELECTROCATALYSTS
ADSORPTION
CARBON BLACK
CATALYST SUPPORTS
CHEMICAL PREPARATION
EXPERIMENTAL DATA
HEAT TREATMENTS
MATERIAL SUBSTITUTION
NITROGEN
OXYGEN
PARTICLE SIZE
PHOTOELECTRON SPECTROSCOPY
PLATINUM
PYROLYSIS
REDUCTION
SULFURIC ACID
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
CARBON
CATALYSTS
CHEMICAL REACTIONS
COHERENT SCATTERING
DATA
DECOMPOSITION
DIFFRACTION
DIRECT ENERGY CONVERTERS
DYES
ELECTROCHEMICAL CELLS
ELECTRON SPECTROSCOPY
ELEMENTS
FUEL CELLS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ACIDS
METALS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
PLATINUM METALS
SCATTERING
SIZE
SORPTION
SPECTROSCOPY
SYNTHESIS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
300505* - Fuel Cells- Electrochemistry
Mass Transfer & Thermodynamics
400400 - Electrochemistry