Manganese-Based Non-Precious Metal Catalyst for Oxygen Reduction in Acidic Media

Abstract

Non-precious metal catalysts (NPMCs) based on manganese (Mn) are prepared by heat treating polyaniline (PANI), manganese acetate and Ketjenblack EC300J (KJ) carbon supports. Using a heat treatment temperature of 950oC, followed by an acid leaching and second heat treatment step, Mn-PANI-KJ catalysts are found to provide onset and half-wave potentials of ca. 0.90 and 0.77 V vs. RHE, respectively, in 0.5 M H2SO4 electrolyte. After 5,000 cycles of electrochemical durability testing, Mn-PANI-KJ demonstrates a half-wave potential loss of only ca. 20 mV, superior to the 80 mV loss for our previously developed iron (Fe)-PANI-KJ catalyst. Increased surface nitrogen concentrations and relative ratios of pyridinic to graphitic nitrogen species were observed at increased Mn-PANI-KJ preparation temperatures, along with the evolution of graphene-like and graphitic nanoshell structures.