Nanoparticles of Ag with a Pt and Pd rich surface supported on carbon as a new catalyst for the oxygen electroreduction reaction (ORR) in acid electrolytes: Part 2

In the first part of this work, the feasibility of developing a catalyst with high activity for the oxygen electroreduction reaction (ORR) in acid media and with low Pt loading was demonstrated by over coating a silver (Ag) nanoparticle with a shell of platinum (Pt) and palladium (Pd) [7]. The results show that best activity is not directly related to a higher PtPd loading on the surface of the Ag. The best catalyst in a series of this type of catalyst is found with Ag@Pt0.3Pd0.3/C which gives a specific activity for oxygen reduction, jk (in units of mA cm−2 of real area), of 0.07 mA cm−2 at 0.85 V vs. NHE, as compared to 0.04 mA cm−2 when with a commercial Pt on carbon catalyst (Pt20/C) is used in an identical electrode except for the catalyst. The mass activity, jm (in units of mA μg−1 of Pt), for Ag@Pt0.3Pd0.3/C is 0.04 mA μg−1 of Pt at 0.85 V vs. NHE, whereas that for the Pt20/C gives 0.02 mA μg−1 of Pt, showing Ag@Pt0.3Pd0.3/C is a lower-cost catalyst, because using a Ag core and Pd with Pt in the shell gives the highest catalytic activity using less Pt. •Simple one–pot synthesis for making platinum (Pt) electrocatalysts supported on carbon.•Catalysts for oxygen electroreduction reaction (ORR) in acid media with low Pt loading.•Optimization of Pt and palladium (Pd) on silver (Ag) core for catalyzing ORR in acids.•Higher ORR activities with Pt, Pd, Ag than Pt, Pd catalysts with same Pt, Pd loadings.