Transition Metal oxides for PEFC Cathodes

摘要

In order to develop non-platinum cathode catalysts for polymer electrolyte fuel cells (PEFCs), transition metal oxides such as zirconium oxides, ZrO_x were examined and their electro-catalytic activity of the oxygen reduction reaction (ORR) and the stability in the acidic medium were evaluated. The electro-catalytic activity of the sputtered ZrO_x catalyst for ORR was measured by the electrochemical methods and its solubility in the acidic medium was measured by ICP analysis. The saturated solubility of the sputtered ZrO_x was 3.2 x 10~(-4) g-Zr dm~(-3) (0.32 ppm) in 1 mol dm~(-3) H_2SO_4 at 70℃. This shows that ZrO_x has high stability in acidic medium. The oxygen reduction current of ZrO_x was observed below 0.85 V, which indicates a clear catalytic activity of ZrO_x for the ORR. The electro-catalytic activity of ZrO_x for ORR was affected by the sputtering conditions and was enhanced by Au.