Activity-composition correlation of AuPt alloy nanoparticle catalysts in electrocatalytic reduction of oxygen

This paper reports the findings of an investigation of the correlation between the catalytic activity and the bimetallic composition of carbon-supported gold–platinum (AuPt/C) nanoparticles (2–4 nm diameters) for the electrocatalytic oxygen reduction reaction. The electrocatalytic activities were characterized using voltammetric and rotating disk electrode techniques, and were also compared with those obtained with Au/C and Pt/C catalysts under the same measurement conditions. The mass activities of the bimetallic catalysts were shown to be not only dependent on the composition, but also the nature of the electrolyte. The catalysts showed a relatively smooth transition from the low activity of Au to the high activity of Pt in the acidic electrolyte. In contrast, a maximized mass activity in the composition region (60–80% Au) of the bimetallic catalyst is revealed which is higher than those of Pt/C and Au/C in the alkaline electrolyte. This remarkable finding suggests a qualitative concurrence with findings from related theoretical modeling and experimental studies, which are discussed in terms of a synergistic activity by the participation of Au in the adsorption of oxygenated species.