1,10-phenanthroline metal complex covalently bonding to poly- (pyrrole-3-carboxylic acid)-coated carbon: An efficient electrocatalyst for oxygen reduction

This paper reports the synthesis and characterization of two none-noble oxygen reduction reaction (ORR) catalysts including the CuPPyPhen/C and the FePPyPhen/C. The catalysts were prepared by covalently bonding of the 1,10-phenanthroline metal complexes with the poly(pyrrole-3-carboxylic acid)/C composite, which was prepared with an oxidative chemical method of polymerization of pyrrole-3-carboxylic acid on the carbon surface. Both catalysts were characterized using electrochemical techniques such as cyclic voltammetry (CV), rotating disk electrode (RDE), as well as rotating ring disk electrode (RRDE) to quantitatively obtain ORR kinetic constants and the reaction mechanisms. The results of the data showed that both catalysts underwent a predominant four-electron pathway for the reduction of oxygen, with the CuPPyPhen/C catalyst exhibited a better ORR activity and stability than that of the FePPyPhen/C and PPyPhen/C catalyst, suggesting that the ORR activity of the catalyst depend on the species of the metal ions which plays a key role to enhance the eletrocatalytic activity and accelerate the step for ORR. The physical morphologies and the surface chemical compositions of the catalysts were examined by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively.