A PEFC With Pt–TiO2/C as Oxygen-Reduction Catalyst

Abstract

Carbon-supported Pt–TiO2(Pt–TiO2/C) catalyst with varying atomic ratio of Pt to Ti, namely, 1:1, 2:1, and 3:1, is prepared by sol-gel method and its electrocatalytic activity toward oxygen-reduction reaction (ORR) is evaluated for the application in polymer electrolyte fuel cells (PEFCs). The optimum atomic ratio of Pt to Ti in Pt–TiO2/C and annealing temperature are established by cyclic voltammetry and fuel-cell-polarization studies. Pt–TiO2/C annealed at 750°C with Pt and Ti in atomic ratio of 2:1, namely, 750 Pt–TiO2/C (2:1), shows enhanced electrocatalytic activity toward ORR. It is found that the incorporation of TiO2 with Pt ameliorates both electrocatalytic activity and stability of cathode in relation to pristine Pt cathode, currently being used in PEFCs. A power density of 0.75 W/cm2 is achieved at 0.6 V for the PEFC with 750 Pt–TiO2/C (2:1) as compared with 0.62 W/cm2 at 0.6 V achieved with the PEFC comprising Pt/C as cathode catalyst while operating under identical conditions. Interestingly, carbon-supported Pt–TiO2 cathode exhibits only 6% loss in electrochemical surface area after 5000 potential cycles while it is as high as 25% for Pt/C.