Enthalpy-regulated PtCoNiCuCr high-entropy alloy for superior oxygen reduction reaction activity and stability in...

The development of high-activity, stable, and low-platinum electrocatalysts for the oxygen reduction reaction (ORR) represents a critical requirement for the widespread commercial deployment of proton exchange membrane fuel cells (PEMFCs). High-entropy alloys (HEAs) are promising candidates. However, the rational design of multi-element catalysts remains challenging, particularly in identifying suitable descriptors for composition screening and ensuring the formation of homogeneous solid solutions. Here, we propose a moderate mixing enthalpy (ΔH_mix) regulation strategy for the rational design and synthesis of a PtCoNiCuCr/C catalyst. The catalyst synthesized via this strategy exhibits outstanding ORR activity, achieving a half-wave potential (E_1/2) of 0.89 V. Notably, its mass activity is approximately 2.4 times higher than that of commercial Pt/C. It also exhibits excellent durability, with only a 5 mV decay in E_1/2 after 30,000 accelerated durability test (ADT) cycles. In practical H₂/O₂ PEMFCs, a peak power density of 1.2 W cm^-2 is achieved. Density functional theory (DFT) calculations further reveal that synergistic electronic interactions among Co, Ni, Cu, Cr, and Pt effectively reduce the overpotential of the rate-determining step, thereby enhancing the intrinsic ORR activity. This work establishes a versatile strategy for engineering HEAs with superior ORR performance.