(605e) Oxygen Electroreduction on Bifunctional Gold-Cobalt Oxide Nanocluster Catalysts

The electro-reduction of oxygen was investigated on nanoclusters of gold and cobalt oxide (Au-CoOx) in alkaline solutions (0.5 M KOH). Au-CoOx binary nanoclusters were prepared with different ratios of Au:Co using pulsed-voltage electrodeposition from electrolytes with varying concentrations of Au and Co cations using a deposition pulse width of 5 ms. The electrocatalytic activities for the oxygen reduction reaction (ORR) were evaluated using voltammetry and a rotating disk electrode (RDE). The addition of Co was found to increase the ORR activity compared to polycrystalline Au. The optimum Au:Co atomic ratio was found to be 96:4. A pseudo-four electron reduction scheme is presented for the Au-CoOx catalyst supporting a bifunctional pathway with formation of the peroxo intermediate from oxygen reduction with water facilitated by Au and the Co participating in the electrocatalytic disproportionation of hydrogen peroxide.