Structure of Pt/Ir/IrO₂ tubes and their electrocatalytic properties in oxidation of small organic molecules

A Pt-Ir-IrO₂NT structural electrocatalysts of high activity is synthesized using IrO₂ thin-wall nanotubes grown in CVD. A solution containing H₂SO₄ and methanol was used. The IrO₂ single-crystal wall constrained the Ir grains nucleated in lattice oxygen removal to a preferred direction. The synthesis procedure involved reduction of IrO₂NT following Pt electrodeposition. The amount of Ir being reduced, the Ir grain size, and the size of deposited Pt strongly influenced the surface area and the catalyst activity. The Pt-Ir-IrO₂NT catalyst reduced at 500°C exhibited a significantly higher activity than those of Pt-IrO₂NT and Pt-IrNT in methanol oxidation, also a higher current density than that of a Johnson-Matthey PtRu catalyst in the high potential region. This is an abstract of a paper presented at the 2006 AIChE Annual Meeting (San Francisco, CA 11/12-17/2006).