Direct methanol fuel cells: The influence of methanol on the reduction of oxygen over Pt/C catalysts with different particle sizes
Two Pt/C catalysts with different particle sizes (Pt/C: 2.5 nm, Pt/C-700Ar: 5.1 nm) were investigated by applying a half-cell configuration - rotating disk electrode (RDE) technique in H2SO4 aqueous solutions in the absence of or in the presence of methanol with different concentrations. Pt/C catalyst exhibited higher mass activity in H2SO4 aqueous solution without methanol and slightly lower mass activity in H 2SO4 plus 0.1 mol/L CH3OH in comparison with that of Pt/C-700Ar catalyst. On the contrary, single direct methanol fuel cell (DMFC) tests showed that Pt/C exhibited higher oxygen reduction reaction (ORR) activity and better cell performance, mainly due to the different kinds of electrolyte properties. Furthermore, it suggested that a better single DMFC performance could be obtained with a smaller particle size Pt-based cathode catalyst.