Oxygen Electroreduction on Bifunctional Gold-Cobalt Oxide Nanocluster Catalysts
Hongfei Lin1, Wei Tang2, and Eric W McFarland1. (1) Chemical Engineering Department, University of California, Santa Barbara, Engineering 2, Room 3357, Santa Barbara, CA 93106, (2) Chemistry, University of California, Santa Barbara, Engineering 2, Room 3357, Santa Barbara, CA 93106
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.