Shape Effect of AuPd Core-Shell Nanostructures on the Electrocatalytical Activity for Oxygen Reduction Reaction in Acid Medium

AuPd core-shell nanostructured materials as electrocatalysts for oxygen reduction reaction (ORR) were synthesized, and the effects of size and shape of the nanoparticles were analyzed. The seed growth method was used to obtain three nanostructures: octahedrons, cuboctahedrons, and cubes, by varying the Au:Pd composition. These different nanostructures were confirmed by SEM. The electrochemical surface areas obtained were 29.50, 18.61, and 32.74 cm² for octahedral, cuboctaedral, and cubic nanostructures, respectively. The cubic nanostructure has the largest ESA due to its smaller nanoparticle size and/or its lower tendency to agglomerate. The electrocatalytic activity for ORR in 0.5 M HClO₄ using rotating disk electrode showed that the best electrocatalytic material was the AuPd cubic nanostructure. Consequently, it was possible to establish that the electrocatalytic activity for ORR in acid medium depends on the electronic and geometric effects related to the Au:Pd composition, the size and shape of the nanoparticles, and core-shell configuration. [Figure not available: see fulltext.].