Enthalpy-driven stabilization of Pt intermetallic catalysts for durable oxygen reduction in proton exchange membrane fuel cells

Pt-based catalysts demonstrate high activity and have become increasingly important in the oxygen reduction reaction (ORR). However, Pt-based catalysts undergo atom migration and dissolution under harsh catalytic conditions, leading to a rapid decline in their performance. In this study, we designed an enthalpy-driven stabilization strategy for platinum-based intermetallic catalysts by leveraging the ultra-negative formation enthalpy (ΔH_f) of the Pt₅Ce phase. The Pt₅Ce exhibits a thermodynamically favored low-energy stable state, which effectively inhibits atomic segregation between Pt and Ce, mitigates active site degradation, and ultimately endows the catalyst with exceptional ORR stability. Concurrently, the Pt-Ce interaction in Pt₅Ce lowers the d-band center of Pt, thereby modulating oxygen intermediate adsorption/desorption kinetics and substantially enhancing intrinsic ORR activity. In acidic conditions, Pt₅Ce/NC exhibits remarkable ORR activity (MA of 0.625 A/mg_Pt) and durability, with only a 9.4% reduction in MA after 40k cycles. In PEMFCs, Pt₅Ce/NC achieves a peak power density of 2.265 W/cm² and maintains its initial voltage at 0.8 A/cm² after 30k cycles, exceeding the DOE 2025 target. This research offers a viable strategy to develop highly active and durable catalysts for PEMFC applications.