Evaluation of TiO2 as catalyst support in Pt-TiO2/C composite cathodes for the proton exchange membrane fuel cell

Anatase TiO 2 is evaluated as catalyst support material in authentic Pt-TiO 2 /C composite gas diffusion electrodes (GDEs), as a different approach in the context of improving the proton exchange membrane fuel cell (PEMFC) cathode stability. A thermal stability study shows high carbon stability as Pt nanoparticles are supported on TiO 2 instead of carbon in the Pt-TiO 2 /C composite material, presumably due to a reduced direct contact between Pt and C. The performance of Pt-TiO 2 /C cathodes is investigated electrochemically in assembled membrane-electrode assemblies (MEAs) considering the added carbon fraction and Pt concentration deposited on TiO 2 . The O 2 reduction current for the Pt-TiO 2 alone is expectedly low due to the low electronic conductivity in bulk TiO 2 . However, the Pt-TiO 2 /C composite cathodes show enhanced fuel cell cathode performance with growing carbon fraction and increasing Pt concentration deposited on TiO 2 . The proposed reasons for these observations are improved macroscopic and local electronic conductivity, respectively. Electron micrographs of fuel cell tested Pt-TiO 2 /C composite cathodes illustrate only a minor Pt migration in the Pt-TiO 2 /C structure, in which anatase TiO 2 is used as Pt support. On the whole, the study demonstrates a stable Pt-TiO 2 /C composite material possessing a performance comparable to conventional Pt-C materials when incorporated in a PEMFC cathode. \ua9 2008 Elsevier B.V. All rights reserved