Segregated Pt on Pd nanotubes for enhanced oxygen reduction activity in alkaline electrolyte

Abstract

Nanoscaled Pt domains were integrated with Pd nanotubes via vapor deposition to yield a highly active electrocatalyst for the oxygen reduction reaction (ORR) in alkaline media. The surface-area-normalized ORR activity of these bi-metallic Pt-on-Pd nanotubes (PtPdNTs) was nearly 6× the corresponding carbon-supported Pt nanoparticle (Pt/C) activity at 0.9 V vs. RHE (1.5 vs. 0.24 mA cm_metal⁻², respectively). Furthermore, the high specific activity of the PtPdNTs was achieved without sacrificing mass-normalized activity, which is more than twice that of Pt/C (0.333 A mg_PtPdNT⁻¹vs. 0.141 A mg_Pt/C⁻¹) and also greater than that of Pd/C (0.221 A mg_Pd/C⁻¹). We attribute the enhancements in specific and mass activity to modifications of the segregated Pt electronic structure and to nanoscale porosity, respectively.