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Elsevier, Diamond and Related Materials, 3(20), p. 322-329, 2011

DOI: 10.1016/j.diamond.2011.01.023

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Oxygen reducing activity of methanol-tolerant catalysts by high-temperature pyrolysis

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Abstract

This study demonstrates the feasibility of platinum-free catalysts, which exhibit not only a high activity in the oxygen reduction reaction (ORR) but also a high tolerance of methanol. A cobalt (II) tetramethoxyphenylporphyrin (CoTMPP) precursor was dispersed in N,N-dimethylmethanamide (DMF), which was ultrasonically stirred for 30 min to yield a homogeneous solution, and then filtered to remove the solvent. The CoTMPP precipitate was pyrolyzed at temperatures of 300, 500, 700 and 900 degrees C in N(2) atmosphere. Raman spectra include strong peaks at 1330 and 1550 cm(-1), which are associated with the D- and G-peaks of pyrolyzed CoTMPP above 500 degrees C, revealing that the original porphyrin structure of CoTMPP yields a network structure of poly-aromatic hydrocarbons upon the pyrolysis. Pyrolyzed CoTMPP loaded on carbon blacks (CoTMPP/C) at 700 degrees C exhibits a higher ORR activity than other various pyrolysis temperatures. In a methanol-containing solution, pyrolyzed CoTMPP/C preferentially undergoes the ORR rather than the methanol oxidation reaction, and so exhibits a high tolerance of methanol. Pyrolyzed CoTMPP has the pyrrolic nitrogen, and part of the cobalt-containing nitrogen chelate is cleaved and bound to other atoms, forming Co-N(x)-C(y(x+y=4),) which are responsible for the ORR activity and the high tolerance of methanol. (c) 2011 Elsevier BM. All rights reserved.