Oxygen Reduction Activity of Vapor-Grown Platinum Nanotubes

Supportless platinum nanotubes (PtNTs) were synthesized by the decomposition of platinum acetylacetonate vapor within anodic alumina templates at 210°C. As synthesized, the nanotubes are nanoparticulate aggregates composed of Pt crystallites approximately 3 nm in diameter and with a range of lengths from 1 μm to 20 μm. Annealing treatments result in crystallite growth and morphological evolution of the tubular nanostructures including the development of nanoscale porosity. In rotating disk electrode measurements carried out in 0.1 M HClO 4 , porous PtNTs annealed at 500°C exhibited a specific activity for oxygen reduction of 2390 ± 423 μA/cm 2 Pt at 0.9 V, comparable to bulk polycrystalline Pt. The electrochemical surface area of the annealed structures was a relatively low 10 m 2 /g, resulting in a moderate overall mass activity of 240 ± 41 mA/mg Pt .