Ligand-Effect-Induced Oxygen Reduction Reaction Activity Enhancement for Pt/Zr/Pt(111) Surfaces with Tensile Strain Relieved by Stacking Faults

Oxygen reduction reaction (ORR) properties are investigated for the Pt/Zr/Pt(111) surfaces prepared through arc-plasma depositions of Zr and Pt on a Pt(111) substrate. The synthesized Pt(111)-shell surfaces on Pt–Zr(111) alloy layers exhibited 3- to 5-fold higher ORR activities than the clean Pt(111): the ligand effect induced by charge transfers between Pt and Zr was considered to be the dominant activity enhancement factor, because tensile strains in the Pt-shell were relieved by the stacking faults generated in the underlaid Pt−Zr alloy layers. Furthermore, the alloy surfaces are durable against an electrochemical potential cycling. The results demonstrate that Zr should be considered for alloying elements of Pt for developments of effective ORR catalysts.