Characterization of composite materials of electroconductive polymer and cobalt as electrocatalysts for the oxygen reduction reaction |
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Authors: | W. Martí nez Millá n,T. Toledano Thompson,L.G. Arriaga,Mascha A. Smit |
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Affiliation: | 1. Centro de Investigación Científica de Yucatán (CICY), Unidad de Materiales, Calle 43 No. 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán, Mexico;2. Centro de Investigación y Desarrollo Tecnológico en Electroquímica S.C. (CIDETEQ), Parque Tecnológico Querétaro, 76700 Querétaro Sanfandila, Querétaro, Mexico |
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Abstract: | Platinum-free electrocatalysts based on electroconductive polymer, modified with cobalt, were prepared and characterized for the oxygen reduction reaction (ORR). The carbon-supported materials were: carbon/polyaniline/cobalt, carbon/polypyrrole/cobalt and carbon/poly(3-methylthiophene)/cobalt. Also the corresponding cobalt-free precursors were studied. EDAX studies show that in cobalt-modified catalysts, significant percentages of cobalt, between 5 and 7% in weight, are present. FTIR, TGA, and EDAX studies confirmed that the addition of cobalt modifies the chemical structure of C–Pani, C–Ppy, and C–P3MT materials. Cyclic voltammetry shows reduction peaks corresponding to the ORR for all materials and kinetic parameters were calculated based on lineal voltammetry using RDE at different rotating speeds. It was found that C–P3MT–Co has highest exchange current densities, followed by C–Ppy and C–Ppy–Co. All samples have Tafel slopes between −110 and −120 V/dec, indicating that the first electron transfer is the decisive step in the global ORR. Potentiostatic tests showed an adequate stability of cobalt-modified samples in acid medium at ORR potentials. Based on the potential range at which ORR occurs, the exchange current density and stability tests, it is concluded that the best material for potential application as fuel cell cathode catalyst is C–Ppy–Co. |
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Keywords: | Electrocatalyst Electroconductive polymers Oxygen reduction reaction (ORR) Polyaniline Polypyrrole Poly(3-methylthiophene) |
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