Effect of Semiconducting Properties of Oxide-Based Compounds on Oxygen Reduction Activity in Acidic Media

摘要

Polymer electrolyte fuel cells (PEFCs) are attractive as energy conversion systems with high conversion efficiency. Although theoretical energy conversion efficiency is high, 83% at 295 K, the actual efficiency is very low because of a large overpotential of oxygen reduction reaction (ORR). In addition, the durability of the catalysts becomes important for commercialization of PEFCs. Pt supported carbon cathode is easy to degrade at high potential region and potential fluctuation. Therefore, we have focused on group 4 and 5 oxide-based compounds as oxides with active sites and electro-conductive supports. We successfully demonstrated that the surface of the oxides had high quality active sites and superior durability against start/stop and load cycle tests.