DFT Study of Polyaniline and Metal Composites as Nonprecious Metal Catalysts for Oxygen Reduction in Fuel Cells

A theoretical study on the oxygen reduction mechanism catalyzed by metal–polyaniline is investigated in detail by means of density functional theory. In the oxygen reduction process, we find that −OH, not H 2 O 2, is the reaction intermediate. The catalytic activities for the studied models decrease in the sequence CoFe–PANI > Fe–PANI (FeFe–PANI) > Co–PANI. This is due to a synergistic effect between heterogeneous metal atoms in CoFe–PANI, which facilitates additional electron donation from the active sites to the adsorbed oxygen reduction intermediates. The doping with cobalt may also decrease the HOMO–LUMO gap in CoFe–PANI, making it more active.