Antisite defect unleashes catalytic potential in high-entropy intermetallics for oxygen reduction reaction

Developing highly active, low-cost, and durable catalysts for efficient oxygen reduction reactions remain a challenge, hindering the commercial viability of proton exchange membrane fuel cells (PEMFCs). In this study, an ordered PtZnFeCoNiCr high-entropy intermetallic electrocatalyst with Pt antisite point defects (PD-PZFCNC-HEI) is synthesized. The electrocatalyst shows high mass activity of 4.12 A mg_Pt^-1 toward the oxygen reduction reaction (ORR), which is 33 times that of the commercial Pt/C. PEMFC, assembled with PD-PZFCNC-HEI as the cathode (0.05 mg_Pt cm^-2), exhibits a peak power density of 1.9 W cm^-2 and a high mass activity of 3.0 A mg_Pt^-1 at 0.9 V. Theoretical calculations combined with in situ X-ray absorption fine structure results reveal that defect engineering optimizes Pt's electronic structure and activates non-noble metal site active centers, achieving exceptionally high ORR catalytic activity. This study provides guidance for the development of nanostructured ordered high-entropy intermetallic catalysts.