Oxygen reduction at the surface of polymer/carbon and polymer/carbon/spinel catalysts in aqueous solutions

In organic/inorganic composite catalysts of the PPy/C/transition metal oxides type oxygen reduction proceeds by a mixed diffusion-adsorption mechanism to form water (a four-electron mechanism). The calculated effective number of electrons for such available catalysts is 3.8 in alkaline electrolytes, which, by efficiency, approaches the ideal value 4.0 for noble metals.