Neighboring iron single atomic sites boost PtCo intermetallic activity 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 compounds enables precise optimization of the 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 mg_Pt⁻¹, which is an 8.1-fold improvement compared to that of 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.