Effect of size in oxygen electroreduction on gold over a wide range of pH

The electroreduction of molecular oxygen on polycrystalline gold and 20Au/C nanoparticles synthesized on XC72R soot is studied over a wide range of pH. Changes in the character of the polarization curves and a considerable increase in half-wave potential (similar to 100 mV) upon transitioning from a compact to a nanodisperse metal were established. A triple increase in the exchange currents is observed for nanoparticles relative to polycrystalline gold. It is suggested that the enhancement of the catalytic activity of a nanodisperse metal is a result of changes in the electronic structure of the d-sublevel of surface atoms.