Flame-Made Ir–IrO<sub>2</sub>/TiO<sub>2</sub> Particles as Anode Catalyst Support for Improved Durability in Polymer Electrolyte Fuel Cells
Thi Thanh Nguyen Ho, Tomoyuki Hirano, Ryosuke Narui, Hiroshi Tsutsumi, Miho Kishi, Yusuke Yoshikawa, Kiet Le Anh Cao, Takashi Ogi
Abstract
The development of metal oxide support with high electrical conductivity has attracted attention to improving the durability and performance of polymer electrolyte fuel cells. Iridium oxide–titanium oxide particles are outstanding candidates, owing to their excellent properties. In this study, catalyst support comprising titanium oxide particles with low-loading iridium–iridium oxide species (Ir–IrO 2 /TiO 2 ) with a chain-like structure was synthesized by a flame aerosol process. The flame aerosol process is a versatile and one-step method allowing the production of metal-loaded metal oxide particles with a low amount of precious metal. The effect of the Ir loading contents on the morphology and electrical conductivity of the synthesized particles was investigated. The volume resistivity of Ir–IrO 2 /TiO 2 particles containing 10 wt % IrO 2 (Ir–IrO 2 /TiO 2 -10) (0.95 Ω cm) was much lower than that of TiO 2 particles (10 8 Ω cm), which demonstrates the improvement of the conductivity of TiO 2 particles resulting from the Ir loading. The electrochemical surface area of 20 wt % Pt-loaded Ir–IrO 2 /TiO 2 -10 particles was 42 m 2 g –1 -Pt, and Pt nanoparticles were distributed homogeneously on the Ir–IrO 2 /TiO 2 particle surface. The performance of a membrane electrode assembly (MEA) based on the developed Ir–IrO 2 /TiO 2 catalyst support as an anode shows no significant differences compared to that of MEA based on a carbon-supported Pt catalyst. MEA prepared from the Ir–IrO 2 /TiO 2 -10 particles exhibited remarkable stability after 20 min testing at a voltage of 1.7 V, whereas the cell potential of a carbon-supported Pt catalyst decreased dramatically under the same conditions.