Selective exposure of platinum catalyst embedded in protective oxide layer on conductive titanium carbide support

Abstract

Despite high conductivity and large surface area, poor corrosion resistance limits the use of carbon black as a fuel cell catalyst support. Here, the formation of two titanium carbide-based core-shell nanostructures with an ultrathin layer of cobalt oxide were studied as alternative to carbon black. Titanium carbide was selected due to its electrical conductivity and high corrosion resistance. Two different nanostructures on TiC supports were prepared with Pt either on or below a cobalt oxide layer. For the sub-oxide Pt catalyst, the oxide could be removed selectively where it covered the Pt to make it partially exposed and catalytically available, yet sufficient Pt was anchored to the remaining oxide to provide stability. This anchoring prevented Pt nanoparticle detachment and aggregation as determined by ∼100% catalytic activity remained at 0.1 M KOH, and ∼92% catalytic activity remained at 0.1 M HClO4 after 16.7 h, room temperature. A core-shell model has computationally been investigated to confirm the function of the cobalt shell as diffusion barrier to protect carbide from oxidation.