# Revealing Robust Atomic Configurations of the Ligand‐Assisted Synthesized High‐Entropy PtIrFeCoNiCu Nano‐Intermetallic Catalysts During Oxygen Reductions in Fuel Cells

## TL;DR

This study develops a new method to create durable, high-performance catalysts for fuel cells using a special alloy structure.

## Contribution

A ligand-assisted strategy synthesizes nano-sized, high-entropy intermetallic catalysts with a core–shell structure for enhanced durability in fuel cells.

## Key findings

- The catalyst shows 6.9 times higher mass activity than Pt/C for oxygen reduction.
- Post-cycling analysis reveals a stable core–shell structure with negligible performance degradation.
- The catalyst achieves a peak power density of 11.6 W mgPt/Ir−1 in fuel cells.

## Abstract

Despite excellent catalytic performance via the “cocktail effect” and the phase stability of high‐entropy alloys (HEAs), their multicomponent surface remains inadequately explored after oxygen reduction reaction (ORR). Moreover, the facile synthesis of nano HEAs is required for practical applications. Herein, nanosized (∼4.8 nm) carbon‐supported PtIrFeCoNiCu intermetallics (PtIr‐iHEA/C), ∼90% ordered, are prepared through a mercaptosuccinic acid (MSA)‐assisted strategy. Combining atomic‐level characterizations and theoretical calculations, the activity is correlated with the evolving surface configuration. Leveraging the activated Pt and Fe sites, PtIr‐iHEA/C displays an initial mass activity (MA) of 1.65 A mgPt/Ir
−1 (0.90 V vs RHE) in rotating disk electrodes (6.9 times that of Pt/C), notably with negligible E1/2 degradation after 50 000 potential cycles. However, post‐characterizations suggest the cycling induces transition metal (TM) leaching, reconstructing the PtIr‐iHEA@Pt core–shell structure. Theoretical analysis attributes the durable performance tothe electronically optimized rigid Pt shell (active sites) and the strain‐anchored sublayer TMs. Consequently, the fuel cell incorporating PtIr‐iHEA@Pt/C delivers a high mass‐normalized peak power density of 11.6 W mgPt/Ir
−1 (H2/Air), and 79% MA retention from 0.75 A mgPt/Ir
−1 after cycling (DOE targets: 0.44 A mgPt
−1, 60% retention). This study uncovers structure‐performance correlations of Pt‐based iHEA for acidic ORR, enlightening the rational HEA design for broader applications.

A facile ligand‐assisted strategy is developed to synthesize nanosized high‐entropy PtIr‐iHEA/C intermetallic catalyst (∼4.8 nm, 90% ordered). Structural analysis during oxygen reduction reveals its surface reconstructions, leading to a core–shell atomic configuration (PtIr‐iHEA@Pt) that originates the superior durability. Combining the high‐entropy constitution, ordered phase, and core–shell structure, the PtIr‐iHEA@Pt demonstrates potential in developing durable and cost‐effective fuel cells.