Ultrafine PtFeMo intermetallic compound nanowires for efficient oxygen reduction reaction in proton exchange membrane fuel cells

To advance the application of proton exchange membrane fuel cells (PEMFCs), it is crucial to develop highperformance oxygen reduction reaction (ORR) catalyst. Pt-based alloy nanowires exhibit excellent ORR activity due to their unique one-dimensional structure, but transition metals undergo spontaneous leaching under the harsh operating condition, often leading to decreased activity. Herein, ultrafine PtFeMo intermetallic compound nanowires were successfully synthesized as a high-performance ORR catalyst for PEMFC. The average diameter of the nanowires was 2.1 nm and the incorporation of inexpensive and high melting point metal Mo improved both catalytic performance and structural stability. The as-prepared ultrafine PtFeMo intermetallic compound nanowires exhibited mass activity of 2.56 A mg Pt- 1 for ORR, which is higher than that of disordered PtFeMo alloy nanowires (1.36 A mg Pt- 1 ) and commercial Pt/C (0.24 A mg Pt- 1 ) in rotating disk electrode test. And it exhibited peak power density of 2716 mW cm- 2 under 250 kPa H2 2-O2 2 single-cell and mass activity of 0.62 A mg P t-1 under 100 kPa H2 2-O2 2 single-cell test in PEMFC. After long-time durability test, the intermetallic compound nanowires maintained their original structure, composition and electrocatalytic performance well, highlighting the importance of Mo incorporation and ordered phase structure generation.