Cu-porphyrin-based polymers in electroreduction reactions of gases

Abstract

In this work, the electrochemical properties of Cu-complexes of di- and tri-amino-substituted tetraphenylporphyrins in dichloromethane were investigated by the cyclic voltammetry method. Electrooxidation of porphyrins in a dichloromethane solution produced polyporphyrin films on the electrode. The formation of polymers occurs through the amino groups of phenyl substituents with the generation of phenazine and dihydrophenazine fragments. The surface morphology and thickness of polyporphyrin films were studied using a scanning electron microscope. The surface of the poly-Cu5,15-di(4′-aminophenyl)-10,20-diphenylporphyrin film is a network of fibers of about 5 µm long and 0.2–0.3 µm thick. The film thickness is 14 µm. The surface of poly-Cu5,10,15-tri(4′-aminophenyl)-20-phenylporphyrin has large branched agglomerates of indefinite shape; the film thickness is 22 µm. The catalytic activity of the obtained polyporphyrin films in oxygen and carbon dioxide electroreduction reactions were evaluated. Poly-Cu5,10,15-tri(4′-aminophenyl)-20-phenylporphyrin was found to be more catalytically active in both reactions, which is evidently associated with a more developed surface of the polymer.