PtCu₃, PtCu and Pt₃Cu Alloy Nanoparticle Electrocatalysts for Oxygen Reduction Reaction in Alkaline and Acidic Media

Dealloying of Pt bimetallic nanoparticles is a promising synthesis method to prepare highly active electrocatalysts for oxygen reduction reaction (ORR) in alkaline and acidic PEM fuel cells. We present here a structural, compositional and electrochemical characterization linked with ORR activity for carbon supported PtCu 3 , PtCu, and Pt 3 Cu alloy nanoparticles in different electrolytes and pH values. The effects of electrolyte and pH are systematically examined on the ECSA and Pt mass based activity (j mass ) for various Pt-Cu alloys. We observed the formation of Cu oxide species and redissolution/redeposition of Cu species during the voltage cycling up to 1.0 V/RHE in 0.1 M KOH. In contrast, the voltage cycling in 0.1 M HClO 4 immediately causes the dissolution of Cu and results in Pt-enriched particle surface. We have correlated the ECSA and mass activity with the as-synthesized composition in dependence on both electrolytes. In summary, after voltage cycling in 0.1 M HClO 4 the values of j mass increase according: Pt 3 Cu < PtCu < PtCu 3 . However, after voltage cycling in 0.1 M KOH the values of j mass increase in the following trend: PtCu 3 < PtCu < Pt 3 Cu. Only after activation process, PtCu 3 core-shell catalyst shows significantly enhanced ORR activity in 0.1 M KOH compared to pure Pt.