Hofmann-type MOFs derived intermetallic L10-PtFe/NC electrocatalysts for boosting oxygen reduction reaction

Intermetallic electrocatalysts have demonstrated significant potential in facilitating the cathodic oxygen reduction reaction (ORR) in fuel cells with enhanced activity and durability. However, it is still an enormous challenge to the facile synthesis of Pt-based intermetallic catalysts with uniform size and high ordering degree. Here, we innovatively fabricate the core-shell structured L10-PtFe intermetallics with Pt skins supported on N-doped porous carbon matrix through one-step pyrolysis of PtFe Hofmann-type metal-organic frameworks (denoted as L10-PtFe/NC). Under the constraints of the porous structure and cyano-ligand bonding, most Fe atoms are alloyed with Pt to form uniform-ordered PtFe intermetallics, while some Fe atoms are atomically dispersed in the carbon framework to form FeNx moieties. Notably, a series of intermetallic PtFe catalysts with different ordering degrees are successfully constructed by adjusting the pyrolysis temperature, which verified that the increase of ordering degree is beneficial to promote the electrocatalytic performance. In particular, the ordered L10-PtFe/NC-800 exhibits superb ORR activity with both mass and specific activities, which are 2.7-folds higher than those of commercial Pt/C. Moreover, after an accelerated durability test, L10-PtFe/NC-800 retains over 90 % mass activity. This work provides a promising approach for the development of efficient Pt-based intermetallic electrocatalysts for fuel cells.