Nanoporous PdCu alloys as highly active and methanol-tolerant oxygen reduction electrocatalysts

Nanoporous (NP) PdCu alloys with three different bimetallic ratios are fabricated by selectively dealloying PdCuAl ternary alloys in sulfuric acid solution. Electron microscopy and X-ray diffraction characterizations demonstrate that selective etching of Al from ternary PdCuAl source alloys in acid medium generates three-dimensional bicontinuous ligament-pore nanostructures with a single-phase face-centered-cubic crystalline structure. NP-PdCu alloys show superior electrocatalytic activity and structure stability toward oxygen reduction reaction (ORR) compared with the commercial Pt/C catalyst. The specific and mass activities for ORR follow the order of NP-Pd50Cu50 > NP-Pd75Cu25 > NP-Pd30Cu70 > Pt/C. It is found that among three PdCu samples NP-Pd50Cu50 exhibits the highest methanol tolerance and catalytic durability for ORR. These experimental observations indicate that incorporation of 50 at.% Cu into Pd accompanied with the network nanoarchitecture is beneficial to maximize the ORR performances of Pd.