Electrodeposited MnO_x/PEDOT Composite Thin Films for the Oxygen Reduction Reaction

Manganese oxide (MnOx) was anodically coelectrodeposited with poly(3,4-ethylenedioxythiophene) (PEDOT) from an aqueous solution of Mn(OAc)2, 3,4-ethylenedioxythiophene, LiClO4 and sodium dodecyl sulfate to yield a MnOx/PEDOT composite thin film. The MnOx/PEDOT film showed significant improvement over the MnOx only and PEDOT only films for the oxygen reduction reaction, with a >0.2 V decrease in onset and half-wave overpotential and >1.5 times increase in current density. Furthermore, the MnOx/PEDOT films were competitive with commercial benchmark 20% Pt/C, outperforming it in the half-wave ORR region and exhibiting better electrocatalytic selectivity for the oxygen reduction reaction upon methanol exposure. The high activity of the MnOx/PEDOT composite is attributed to synergistic charge transfer capabilities, attained by coelectrodepositing MnOx with a conductive polymer while simultaneously achieving intimate substrate contact.