Selective Coating of Anatase and Rutile TiO2 on Carbon via Ultrasound Irradiation: Mitigating Fuel Cell Catalyst Degradation

Abstract

Before mass produced automotive fuel cell technology can be made practical, the oxidative instability of the carbons currently, used as the catalyst support at the oxygen electrode, must be addressed. This article describes a method for coating carbon (Vulcan XC-72) with protective barriers of titanium dioxide (titania) and provides the results of physical characterization tests on those materials. By combining the sol-gel coating process with high intensity ultrasonication and choosing the appropriate precursor, either the anatase or rutile phases of titania can be produced. More complete coverage of the carbon was provided by the anatase process. Accelerated gas-phase oxidation tests showed that platinized, anatase-coated carbon oxidized at 1∕5 the rate of untreated carbon while the rutile phase showed a mass loss of 1∕3 that of untreated carbon.