Electrocatalytic Activity and Stability of Titania-Supported Platinum–Palladium Electrocatalysts for Polymer Electrolyte Membrane Fuel Cell

Abstract

Titania-supported platinum–palladium electrocatalysts (PtPd/TiO₂) were synthesized and investigated as alternative catalysts for the oxygen reduction reaction (ORR). Transmission electron microscope images revealed a uniform distribution of metal nanoparticles (<i>d</i>_M = 3–5 nm) on the TiO₂ support. An increase in ORR activity has been observed with an increase in the Pd content of the bimetallic alloy up to 30%, and beyond this composition, the decrease in catalytic activity has been found to be due to the blocking of Pt active sites by a large amount of Pd in the catalyst. The PtPd/TiO₂ electrocatalyst with a Pt/Pd composition of 70:30 shows activity comparable to that of a commercial Pt/C catalyst (TKK) in rotating ring-disk electrode studies. The accelerated durability test results show good stability for the PtPd/TiO₂ electrocatalysts at high potentials in terms of minimum loss in the Pt electrochemical surface area. The high stability of the PtPd/TiO₂ electrocatalyst synthesized in this investigation offers a new approach to improve the reliability and durability of polymer electrolyte membrane-based fuel cell cathode catalysts