A mechanistic study of 4-aminoantipyrine and iron derived non-platinum group metal catalyst on the oxygen reduction reaction

A highly active non-platinum group metal (non-PGM) catalyst derived from iron and 4-aminoantipyrine precursors was synthesized using a sacrificial support method (SSM) to obtain a highly porous, open framed structure. The ratio of iron to 4-aminoantipyrine had been previously optimized to catalyze the reduction of oxygen in both acid and alkaline media. In this study, the mechanism of the reduction of oxygen in both media was investigated, and it was found to follow the 2 × 2 pathway. On its face, electrochemical analysis seems to suggest that the direct 4 electron transfer pathway is favored due to the low peroxide yield, but a closer examination reveals that the 2 × 2 pathway is followed, where the fast step is the partial reduction to peroxide, and the ensuing reduction step to water is also fairly rapid.