Highly conductive polyporphyrin films obtained by superoxide-assisted electropolymerization of para - aminophenyl porphyrin

The process of deposition of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (H2T(4-NH2Ph)P) electopolymer films induced by superoxide anion radical in dimethyl sulfoxide (DMSO) has been studied. By the methods of electrode impedance spectroscopy and atomic-force microscopy it has, for the first time, been proved that it is possible to form a poly-H2T(4-NH2Ph)P film in DMSO in potentiostatic conditions at oxygen electroreduction potentials. Charge transfer through the poly-H2T(4-NH2Ph)P film has been characterized by modeling electrochemical impedance spectroscopy (EIS) data. It has been shown that in potentiostatic conditions, the formation of a poly-H2T(4-NH2Ph)P film induced by superoxide anion radical consists of at least two stages. At the first stage, the resistance of the surface film changes insignificantly, and at the second one it increases approximately linearly over time. Using the vibrational spectroscopy we have determined the type of binding of monomer fragments in the polyporphyrin film. The morphology and thickness of the deposited polyporphyrin films have been studied by the methods of atomic force microscopy. Based on the resistance and thickness estimates, we have determined the value of specific conductivity of the obtained film (about 4.2.10(-4) S Cm-1). The metal-free aminophenyl porphyrin electopolymer was also successfully tested as an electrocatalyst for the oxygen reduction reaction.