TiO2 and Al2O3 promoted Pt/C nanocomposites as low temperature fuel cell catalysts for electro oxidation of methanol in acidic media

Abstract

Carbon corrosion and platinum dissolution are the two major catalyst layer degradation problems in polymer electrolyte membrane fuel cells (PEMFC). Ceramic addition can reduce the corrosion of carbon and increase the stability of catalysts. Pt/TiO2, Pt/TiO2-C, Pt/Al2O3 and Pt/Al2O3-C catalysts were synthesized and characterized. Electrochemical surface area of Pt/TiO2-C and Pt/Al2O3-C nanocomposite catalysts was much higher than the Pt/TiO2 and Pt/Al2O3 catalysts. Peak current, specific activity and mass activity of the catalysts was also determined by cyclic voltammetry and were much higher for the carbon nanocomposites. Exchange current densities were determined from Tafel plots. Heterogeneous rates of reaction of electro oxidation of methanol were determined for all the catalysts and were substantially higher for titania catalysts as compared to alumina added catalysts. Mass activity of Pt/TiO2-C was much higher than mass activity of Pt/Al2O3-C. Stability studies showed that addition of ceramics have increased the catalytic activity and durability of the catalysts considerably.