Electrochemistry of shape-controlled catalysts:: Oxygen reduction reaction on cubic gold nanoparticles

This paper describes the electrochemical behavior of shape controlled, deliberately large Au nanoparticles that have been synthesized using a seed-mediated growth method in the presence of cetyl trimethyl ammonium bromide. Transmission electron microscopy micrographs and selected area electron diffraction patterns revealed 40 nm Au nanoparticles with a preferentially cubic shape suggesting a high amount of (100) surface sites. In situ electrochemical structure-sensitive reactions such as lead underpotential deposition confirm that the surface of the nanoparticles contains a large quantity of wide (100) domains. As a consequence, the nanoparticles showed a very high catalytic activity for the four electron oxygen reduction paths in alkaline media. Thus, water was obtained as the final product of the reaction in the whole potential range, while hydrogen peroxide was obtained only in the lower potential region, in a similar way as reported for Au (100) electrodes.