Factors Which Affect Oxygen Reduction Activity of Niobium Added Titanium Oxides as Non-Platinum Cathodes for Polymer Electrolyte Fuel Cells

Development of non-platinum electrocatalysts for oxygen reduction reaction is required for wide commercialization of PEFCs. We have focused on group 4 and 5 metal oxide-based compounds as non-precious metal cathodes. Although we needed to investigate the active sites of oxide-based cathodes to enhance the oxygen reduction activity, it was difficult to divide the effect of the nature of the active sites and the electrical conductivity of the catalysts. In this study, we prepared poly-crystalline Nb added TiO2 rods with high electric conductivity as model electrodes. We suggested that the Ti3+ species in the rutile structure might be active sites for the oxygen reduction activity.