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 H2O2, 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.