La Incorporated into L10-PtFe Nanoalloys as a Highly Active and Durable Oxygen Reduction Catalyst

Pt–transition metal intermetallic compounds have been recognized as promising catalysts for oxygen reduction reaction (ORR). However, further enhancing the activity and durability of this kind of catalyst is still necessary. Herein, we report a novel L10-type PtFe intermetallic nanoalloy with the partial substitution of Fe sites by La as a highly active and stable catalyst towards ORR. This new intermetallic nanoalloy retains an ordered structure after the incorporation of La confirmed by XRD, XPS and TEM results and the ordered PtFe0.5La0.5 nanoparticles are embedded in porous carbon (L10-PtFe0.5La0.5@C) in very uniform particle size of around 2 nm. This L10-PtFe0.5La0.5@C catalyst exhibits a half-wave potential of 933 mV, which is about 12 mV and 70 mV higher than those of L10-PtFe@C and commercial Pt/C catalysts, respectively. Moreover, it also achieves an enhanced mass activity of 0.79 A mgPt−1 at 0.90 V, which outperforms the performance of commercial Pt/C (0.10 A mgPt−1). In addition, it also shows excellent stability with only 3 mV negative shift in half-wave potential after 20k CV cycles of accelerated durability testing. This high activity and stability may be attributed to the incorporation of La in the PtFe lattice, which induces the formation of a compressively strained Pt overlayer in acidic media which not only tunes the surface strain of Pt sites but also possesses robust resistance to the dissolution of Fe and La. This work also provides a new direction for the development of Pt-based intermetallic catalysts for efficient catalysis applications.