Synthesis of bimetallic Pt/Pd nanotubes and their enhanced catalytic activity in methanol electro-oxidation

In this work, we successfully synthesized a vertically-aligned bimetallic Pt/Pd nanotube array by using anodic aluminum oxide (AAO) template-assisted electro-deposition. The resulting nanostructures exhibited higher catalytic activity in methanol oxidation than either individual constituent (Pt or Pd). The facile synthesis of the Pt/Pd tubular nanostructure was inspired by the previously developed thin-walled Pd nanotube formation mechanism, which takes advantage of the surface hydroxyl chemistry of the AAO template. The content of Pt in the bimetallic Pt/Pd nanotubes could reach up to 50%. The inner and outer walls of the perpendicular open Pt/Pd nanotubes increased the ratio of the surface area to the mass relative to the solid nanorod structure, resulting in a higher current density in methanol oxidation. More importantly, the synergistic electronic effect between Pt and Pd gave rise to the enhanced catalytic activity in methanol oxidation, as evidenced from comparisons of the onset potentials and CO oxidation behaviors. Thus, vertically-aligned bimetallic Pt/Pd nanotubes may act as a better catalyst in methanol oxidation than the single-component Pt counterpart.