Two different metalloporphyrin composites as promising orr catalysts

In this work we prepared the materials based on individual metal complexes of 5,10,15,20-tetrakis(3-aminophenyl)porphyrin and composites containing two different metalloporphyrins. For the films of individual porphyrins, we found the following order of film formation rate and thickness: CuT(3-NH₂Ph)P > NiT(3-NH₂Ph)P > FeClT(3-NH₂Ph)P = MnClT(3-NH₂Ph)P > CoClT(3-NH₂Ph)P. Combination of porphyrins with relatively high and low deposition rates led to the slowed down film formation. A hypothesis was proposed to explain the nature of this phenomenon. The spectra of the films confirmed formation of the composites. It was found that the resulting films have low roughness and are active in the oxygen electroreduction reaction (ORR) in an alkaline medium. Among the materials based on the individual porphyrins, CoClT(3-NH₂Ph)P films showed the best catalytic activity. We found out that the ORR onset potential and Tafel slope values can be significantly reduced by using the composites containing two different metalloporphyrins. The composite based on cobalt and manganese aminophenylporphyrins demonstrated the ORR onset potential of − 113 mV vs Ag/AgCl, which is about 100 mV more negative than that of the Pt/C catalyst.