(419d) Carbon-Doped TiO2 Nanocoating As Durable Pt Electrocatalyst Support

In this presentation, we report a conductive TiO₂ nanocoating on carbon nanotubes (CNTs) as an electrocatalyst support that shows a significant enhancement in catalyst activity and durability. By using CNTs as support for the TiO₂ nanocoating, the nannoscale morphology of the oxide was retained during heat treatment. The oxide was made conductive by doping with carbon. After carbon doping, X-ray photoelectron spectroscopy suggests a red shift in the binding energy of Ti 2p, implying a suboxide formation. X-ray absorption near-edge structure showed the mid-edge and post-edge up to 5010 eV in the carbon-doped TiO₂, which are attributed to a 1s→4p transition and promotion of a photoelectron to higher vacant orbitals of Ti and Ti-O anti-bonding states in the Ti coordination environment. The observed smaller coordination number implies that the suboxide was formed with substitutional carbon. On the other hand, extended X-ray absorption fine structure showed that the carbon also exists in interstitial positions. Electrochemical studies showed that the carbon-doped TiO₂/CNTs has a much greater electrical conductivity than that of undoped TiO₂/CNTs, demonstrating that carbon doping is an effective way to achieve conductivity in the oxide. Pt supported on carbon-doped TiO₂/CNTs (Pt/c-TiO₂/CNTs) showed better oxygen reduction activity than a commercial catalyst Pt/C. The Pt/c-TiO₂/CNTs still exhibits very good activity after cycling for 5000 times, demonstrating a much better catalyst durability than Pt/C. The much better durability was attributed to strong metal-support interactions.