Atomic‐Scale Interface Engineering: Boosting Oxygen Electroreduction over Supported Ternary Alloys Fabricated by Carbon‐Assisted Galvanic Replacement

Abstract Interfacial ensemble and ligand engineering is a smart strategy to economically and efficiently improve electrocatalytic activity of composite catalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. In this paper, a ternary PtPdCu alloy, chemically coupled with carbon black (11.9 wt% Pt), is synthesized in large scale via carbon‐assisted galvanic replacement in anhydrous ethylene glycol (EG) solutions. The obtained low platinum alloy disperses well on carbon with an average size of about 1.9 nm. In 0.1 m HClO₄, the supported alloy exhibits superior ORR activity and long‐term stability than those obtained by unsupported alloy or commercial Pt/C (20 wt% Pt). The substantially improved property can result from the presence of interfacial ensemble and ligand effects derived from d–p‐orbital hybridization of Pt and C atoms at atomic level, while the good durability is responsible for enriched Pd atoms at near‐surface layers that hinder the leaching of Pt and Cu atoms in their alloys, as verified by density functional theory (DFT) results. Therefore, interface engineering tuned by modified galvanic replacement may be a feasible strategy for large‐scale preparation of supported catalysts with nanoengineered interfaces.