Iron(III) tetramethoxyphenylporphyrin (FeTMPP-C1) as electrocatalyst for oxygen reduction in direct methanol fuel cells

Iron(III) tetramethoxyphenylporphyrins (FeTMPP-C1) adsorbed on high-area carbons were heat treated in an inert atmosphere at various temperatures ranging from 200–1000 °C to produce catalyst for the electroreduction of oxygen in acid electrolytes. It was found that the specific surface area of the FeTMPP-C1/C catalysts linearly decreases with increase of the FeTMPP-C1 loading on RB carbon. The electrical resistivity of the catalyst decreases with the increase of heat treatment temperature in the range of 200 to 800 °C, then it increases beyond 800 °C. The results obtained with elemental analysis, FTIR spectroscopy and XPS techniques indicate that the onset temperature for partial decomposition for the FeTMPP chelate occurs at temperatures of about 400–500 °C. The surface concentrations of both iron and nitrogen on the carbon support increase as the heat treatment temperature increases, and the maximum occurs at 700 °C. Some possibilities about the nature of active sites in the catalyst are discussed.