Enhanced oxygen reduction reaction by bimetallic CoPt and PdPt nanocrystals

Abstract

Excellent oxygen reduction reaction (ORR) activity of Pt-based bimetallic alloys like CoPt and PdPt has been studied in detail. A simple solution-phase synthetic procedure for the bimetallic alloys of CoPt and PdPt is described here. This method, involving a single-step reaction, is believed to be suitable for large-scale synthesis of both monometallic and multimetallic nanocrystals with required size and shape. Among various catalyst compositions, Pd₂₂Pt₇₈ and Co₁₅Pt₈₅ catalysts have shown excellent ORR activity compared with Pt/C and commercial PtCo/C (PtCo/C(comm)) samples. At 0.9 V, Co₁₅Pt₈₅/C and Pd₂₂Pt₇₈/C exhibit mass activities with values ∼3.8 times and ∼2.1 times higher than that of Pt/C, and Co₁₅Pt₈₅/C exhibits 1.8 times higher activity than that of PtCo/C(comm). Quantification and the effect of surface-oxygenated species generated at higher potentials were studied by stripping voltammetry, in the form of total charge.