261389 Carbon-Doped TiO2 Nanocoating As Durable Pt Electrocatalyst Support

Wednesday, October 31, 2012: 9:30 AM
317 (Convention Center )
Kan Huang, Chemical and Biological Engineering, Missouri University of Science and Technology, Rolla, MO, Kotaro Sasaki, Materials Science, Brookhaven National Lab, Upton, NY, R. R. Adzic, CO, Brookhaven National Laboratory, Upton, NY and Yangchuan Xing, Dept. of Chemical and Biological Engineering, Missouri University of Science and Technology, Rolla, MO

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.

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