Surface-enriched Pd/C electrocatalysts with a low load of Pt prepared by surface redox reactions for the oxygen reduction reaction

Pt–Pd/C bimetallic catalysts with low platinum contents were synthesized by surface redox reactions. In this method, hydrogen preadsorbed on the palladium surface of the parent catalyst (Pd/C) acts as a reducer of the PtCl₆⁻ species, allowing a selective deposition and closer interaction between both metals (Pt–Pd). The physicochemical study was carried out by XRD, HAADF-STEM, HRTEM, EDS, and electronic interaction between Pt–Pd was characterized by XPS. The electrochemical characterizations by CV, CO stripping, and steady-state LSV toward ORR using RDE indicate that 1%Pt–Pd/C sample exhibited the best results. The present work demonstrates that the selective incorporation of Pt in low quantities on the Pd surface increases the interaction between both metals, producing electronic interactions, synergetic effects, and an enhanced electrocatalytic activity toward the ORR.