Activity of dealloyed PtCo3 and PtCu3 nanoparticle electrocatalyst for oxygen reduction reaction in polymer electrolyte membrane fuel cell

We report a comparative study of the alloy formation and electrochemical activity of dealloyed PtCo3 and PtCu3 nanoparticle electrocatalysts for the oxygen reduction reaction (ORR). For the Pt–Co system the maximum annealing temperatures were 650 °C, 800 °C and 900 °C for 7 h to drive the Pt–Co alloy formation and the particle growth. EDS and XRD were employed for the characterization of catalyst powders. The RDE and RRDE experiments were conducted in 0.1 M HClO4 at room temperature.We demonstrate that the mass and surface area specific ORR activities of Pt–Co and Pt–Cu alloys after voltammetric activation exhibit a considerable improvement compared to those of pure Pt/C. The dealloyed PtCo3 (800 °C/7 h) electrocatalyst performs 3 times higher in terms of Pt-based mass activity and 4–5 times higher in terms of ECSA-based specific activity than a 28.2 wt.% Pt/C. Dealloyed Pt–Co catalysts (800 °C/7 h) show the most favorable balance between mass and specific ORR activity with a particle size of 2.2 ± 0.1 nm. We hypothesize that geometric strain effects of the dealloyed Pt–Co nanoparticles, similar to those found in dealloyed PtCu3 nanoparticles, are responsible for the improvement in ORR activity [1].