Neighboring Iron Single Atomic Sites Boost PtCo Intermetallic for High-Durability ORR Electrocatalysis

Abstract

Advancing fuel cell technology hinges on developing stable, efficient Pt-based catalysts for the oxygen reduction reaction (ORR), yet challenges like the high cost and limited durability of Pt-based materials persist. Here, we present an electrocatalyst that harnesses the strong interaction between Fe single atoms and neighboring ordered PtCo alloys (O-PtCo-FeNC) confined in microporous carbon. The unique coordination of FeN3 sites with PtCo intermetallic enables precise optimization of catalyst size and structure, boosting PtCo intermetallic activity and yielding exceptional ORR performance. This is verified by a half-wave potential of 0.86 V vs. RHE in 0.5 M H2SO4 and a mass activity of 1.34 A/mgPt, achieving an 8.1-fold improvement over Pt/C, while maintaining exceptional durability for over 50,000-cycles. In-situ characterization and theoretical calculations reveal that isolated Fe sites reduce the d-band center of neighboring Pt sites, weakening adsorption energy and synergistically enhancing both activity and stability. When deployed in the air cathode of a hybrid acid/alkali Zn-air battery, the catalyst delivers an outstanding open circuit voltage of 2.32 V and a peak power density of 751 mW cm-2. This integration of intermetallic compounds with single-atom sites establishes a new benchmark for advanced ORR electrocatalysts, marking a significant advancement in fuel cell technology.