Gouerec P, Savy M, Riga J (1998) J Electrochim Acta 43:743 Lalande G, Cote R, Tamizhmani G, Guay D, Dodelet JP, Dignardbailey L, Wengands LT, Bertrand P (1995) Electrochim Acta 40:2635īiloul A, Gouerec P, Savy M, Scarbeck G, Besse S, Riga J (1996) J Appl Electrochem 26:1139 Ladouceur M, Lalande G, Guay D, Dodelet JP, Dignardbailey L, Trudeau ML, Schulz R (1993) J Electrochm Soc 140:1974 Sun GQ, Wang JT, Savinell RF (1999) J Appl Electrochem 28:1087Ĭhu D, Jiang R (2002) Solid State Ionics 148:591īiloul A, Contamin O, Scarbeck G, Savy M, Vandenham D, Riga J, Verbist JJ (1992) J Electroanal Chem 335:163 Gojkovic SJ, Gupta S, Savinell RF (1999) J Electroanal Chem 462:64 Gouerec IP, Savy M (1999) Electrochim Acta 44:2653 Levendosky S, Atanassov P, Davey J, Zelenay P (2004) The Electrochemical Society, Meeting Abstracts, abs. The developed methodology, described herein, combines model curve-fits and principal component analysis (PCA), resulting in a quantitative and unambiguous understanding of the chemical composition and structure of complex electrocatalysts. A thin layer of CoO coats these metallic cobalt phases. The remaining cobalt is present in crystallites of metallic Co. Approximately 50% of the metal is distributed as Co 2+, associated with N 4-centers.
As a result of these studies it is established that the catalyst is a nano-composite of highly dispersed pyropolymer with some remaining N x-centers inserted into a graphite-like matrix.
Principal Component Analysis (PCA) applied to quantitative results from the curve-fits of both types of spectra facilitates visualization and identification of the chemical species that are formed or destroyed, and simplifies evaluation of critical correlations. High-resolution Co2p, C1s, N1s and O1s XPS spectra acquired from precursors and electrocatalysts pyrolyzed at various experimental conditions were curve-fit using (a) individual peaks of constrained width and shape as well as (b) experimentally obtained photopeaks from the precursor with additional peaks required for a complete curve fit. The catalysts represent highly dispersed, self-supported nano-composites that demonstrate electrocatalytic performance for oxygen reduction and practically no activity in methanol electro-oxidation. The chemical structure of non-platinum electrocatalysts obtained from cobalt porphyrins (CoTMPP or CoTPP) by pyrolysis is investigated by X-ray Photoelectron Spectroscopy (XPS).
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