PdAg@Pd core-shell nanotubes: Superior catalytic performance towards electrochemical oxidation of formic acid and methanol

The catalytic activity of alloy nanomaterials can be well modulated through the electrochemical dissolution of the more active component from alloy nanomaterials. In this paper, PdAg alloy nanotubes of diverse Pd to Ag ratio are prepared by galvanic displacement electrochemical reaction. The Ag-leached PdAg nanotubes are characterized by cyclic voltammetric scans, high-angle annular dark-field scanning transmission electron spectroscopy, energy dispersive X-ray elemental mapping and X-ray photoelectron spectroscopy measurements and demonstrate the formation of PdAg@Pd core-shell nanotubes structure with roughed surface and largely enhanced electrochemical surface area. The PdAg@Pd core-shell nanotubes show significantly enhanced catalytic activities and durability towards electro-oxidation of formic acid and methanol than the as-prepared PdAg nanotubes, with the mass activity and specific activity of 1.93 A mg−1 and 2.67 mA cm−2 towards formic acid respectively, which are 7.8 and 4.8 times that of Pd/C. The increased catalytic performance is ascribed to the unique surface and electronic structure of PdAg@Pd core-shell nanotubes.