Titanium Dioxide-Supported Platinum Catalysts

Titania supported Pt (Pt/TiO2) and Pt-alloy (Pt-Pd/TiO2) electrocatalysts were synthesized and investigated as alternative cathode catalysts for polymer electrolyte membrane fuel cells (PEMFCs). Transmission electron microscope (TEM) images revealed uniform distribution of Pt nanoparticles (d(Pt) = 3-5 nm) on the TiO2 support. In-house developed accelerated durability test (ADT, continuous potential cycling between 0.6 and 1.4 V) in half-cell condition indicated nearly ten-fold higher ORR activity (1.20 mA cm(-2)) when compared to the Pt/C catalyst (0.13 mA cm(-2)). The Pt/C catalyst showed no activity in fuel cell testing after 2000 potential cycles due to severe carbon corrosion, Pt dissolution, and catalyst particle sintering. Conversely, the Pt/TiO2 electrocatalyst showed only a small voltage loss (0.09 V at 0.8 A cm(-2)) even after 4000 cycles. Pt-Pd/TiO2 shows better stability than Pt/C in accelerated durability tests. The ECSA of Pt100Pd0, Pt90Pd10, Pt80Pd20, and Pt/C are 14.7, 17.3, 16.3, and 4.9 m(2) g(-1) after 1500 cycles of accelerated durability testing. Among all catalysts tested, Pt80Pd20 shows the highest performance and stability in RDE and Fuel Cell testing. The ADT results showed excellent stability for the Pt/TiO2 and Pt-Pd/TiO2 electrocatalysts at high potentials in terms of minimum loss in the Pt electrochemical surface area (ECSA).