(277e) Structure of Pt/Ir/Iro2tubes and Their Electrocatalytic Properties in Oxidation of Small Organic Molecules

Pt/Ir/IrO2 electrocatalyst of one dimensional feature has been prepared by reduction of IrO2 nanotubes following electrodeposition of Pt. The IrO2 nanotubes were grown by chemical vapor deposition and reduced at elevated temperatures in vacuum. The partially reduced Ir/IrO2tubes were decorated with Pt on surface using pulsed galvanostatic deposition. Structure variations in this IrO2 thin-wall material before and after reduction were studied using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The electrochemical activity in oxidation of small organic molecules was measured using cyclic voltammetry. Amazingly, the morphology of IrO2 nanotubes changes little if there is some amount of IrO2 phase remains after reduction. And the anodic activity of Pt decorated Ir/IrO2tubes increases dramatically. The response current in cyclic voltammogram of Pt/Ir/IrO2tubes is 6-7 times more active than that of Pt/IrO2tubes (without reduction). The maximum CV response current of Pt/Ir/IrO2tubes at 10 mVs-1 in 2.5 M methanol and 0.5 M H2SO4 was around 140 mAcm-2, and the PtIr loading on the substrate was 0.45 mgcm-2 with Pt:Ir=1:3.5 ignoring oxygen. The activity of Pt/Ir/IrO2tubes is comparable to that of sol-gel derived Pt1.8-Ir mixed catalyst reported by Tsaprailis and Birss (Electrochem. Solid-State Lett 2004).