Ultrafast crystallinity engineering of PtCo3 alloy for enhanced oxygen reduction reaction

Efficient electrocatalysts for oxygen reduction reaction (ORR) show significant importance for advancing the performance and affordability of proton exchange membrane fuel cells and other energy conversion devices. Herein, PtCo3 nanoalloys dispersed on a carbon black support, were prepared using ultrafast Joule heating method. By tuning the heating modes, such as high-temperature shock and heating for 2 s, two kinds of PtCo3 nanoalloys with varying crystallinities were obtained, referred to as PtCo3-HTS (average size of 5.4 nm) and PtCo3-HT-2s (average size of 6.4 nm), respectively. Impressively, PtCo3-HTS exhibited superior electrocatalytic ORR activity and stability (E1/2 = 0.897 V vs. RHE and 36 mV negative shift after 50,000 cycles), outperforming PtCo3-HT-2s (E1/2 = 0.872 V and 16.2 mV negative shift), as well as the commercial Pt/C (20 wt%) catalyst (E1/2 = 0.847 V and 21.0 mV negative shift). The enhanced ORR performance of PtCo3-HTS may be attributed to its low crystallinity, which results in an active local electronic structure and chemical state, as confirmed by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) analyses. The ultrafast Joule heating method showed great potential for crystallinity engineering, offering a promising pathway to revolutionize the manufacturing of cost-effective and environmentally friendly catalysts for clean energy applications.