Research Of Catalysts For Thealkaline Polymer Electrolyte Membrane Fuel Cell

In alkaline medium, the oxygen reduction reaction (ORR) has higher rate than that in acidic medium. So the alkaline polymer electrolyte membrane fuel cell (APEFC) can choose the non-noble metal catalysts such as nickel, cobalt, manganese transition metals for cathode. These catalysts known for their high efficiency in alkaline medium and low cost. The non-noble metal catalysts can reduce the cost of fuel cells ought to be a long-term choice. In this paper, we synthesized three systems of non-noble metal catalysts:(1) MnCo2O4 has been synthesized by solid phase synthesis method to prepare MnCo2O4/C non-precious metal catalysts by heat treatment for alkaline polymer electrolyte membrane fuel cells. The heat treatment temperatures 600℃、700℃、800℃ and 900℃ were investigated in order to identify the optimum reaction condition. The results indicate that when the heat treatment temperature is 700℃, the catalyst has a higher electrocatalytic activity than the others and the ORR onset potential of the catalyst is 0.84V, the electron transfer number is 3.48 and the oxygen reduction reaction process involves two electron process and four electron process.(2) MnCo2O4 has been synthesized by solid phase synthesis method to prepare MnCo2O4/N-C non-precious metal catalysts for alkaline polymer electrolyte membrane fuel cells.MnCo2O4 loading amounts and reaction temperatures were investigated in order to identify the optimum reaction condition. The results indicate that the catalyst with 15 wt.% MnCo2O4 loading prepared at 900℃ has a higher electrocatalytic activity than others and the ORR onset potential of the catalyst is 0.90V. The stability of the catalyst is better than that of commercial Pt/C catalyst. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) show that 15 wt.% MnCo2O4/N-C catalyst contains more graphitic carbon and nitrogen than the others. These characteristics can well explain for its excellent ORR performance.(3) CoFe2O4 has been synthesized by microwave synthesis method to prepare a series of CoFe2O4/N-C non-precious metal catalysts for alkaline polymer electrolyte membrane fuel cells. CoFe2O4/N-C non-precious metal catalysts have a higher electrocatalytic activity than CoFe2O4 and PANI. CoFe2O4 loading amounts and reaction temperatures were investigated in order to identify the optimum reaction condition. The results indicate that the catalyst with 5 wt.% CoFe2O4 loading prepared at 1000℃ has a higher electrocatalytic activity than the others and the ORR onset potential of the catalyst is 0.88V. The stability of the catalyst is better than that of commercial Pt/C catalyst. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) show that 5 wt.% CoFe2O4/N-C catalyst contains more carbon atoms with surface defects which can provide more catalytic active sites and graphite nitrogen than the others. These characteristics can well explain for its excellent ORR performance.