Functional DMFC Cathode Catalysts and Supports Based on Niobium Oxide Phase

Composite electrocatalysts consisting of platinum nanophase supported on carbon black decorated with niobium oxide phase were prepared by a two step precipitation/reduction procedure. The intrinsic catalytic activity of these materials was evaluated for the oxygen electroreduction reaction, measured in the absence and presence of methanol. It was found that the NbxOy-composite materials are more hydrophilic and thus initially have lower intrinsic catalytic activity for oxygen reduction. However, materials containing NbxOy offer better overall platinum mass utilization, achieved through much better dispersion of the platinum nano-phase. Such advantageous dispersion is observed even for high metal loadings. Another advantage of these materials is minimal effect of poisoning with the intermediates formed during methanol oxidation that results in the enhanced methanol tolerance in direct methanol fuel cells (DMFC)