"Three people make a tiger": Honeycomb nitrogen-doped carbon supported PtFe&Fe3C with ultralow Pt for oxygen reduction reaction.

Here, an ultralow Pt (∼2 wt%) catalyst, honeycomb NC-supported PtFe&Fe3C (PtFe&Fe3C/HNC), is prepared for oxygen reduction reaction (ORR). This catalyst contains three advantages: (1) a large number of mesopores in HNC is beneficial for the exposure of active sites and rapid diffusion of O2; (2) the introduction of Fe into PtFe alloy can effectively alter the electronic structure of Pt, weaken the oxygen binding energy between Pt and reaction intermediates to enhance the intrinsic activity of Pt; (3) Fe3C not only further regulate the electronic structure of Pt by transferring electrons to Pt, but also serve as an active site to enhance the catalytic efficiency. A significant synergistic effect of HNC, PtFe and Fe3C makes the ORR catalytic activity of PtFe&Fe3C/HNC far superior to that of the commercial 20 wt% Pt/C. Specially, PtFe&Fe3C/HNC has an excellent ORR catalytic activity in 0.1 M KOH with the peak potential and half-wave potential as high as 0.939 V and 0.917 V (vs. RHE), respectively, along with nearly no activity lost in stability and anti-methanol test. This work provides a strategy for ultralow Pt catalysts with high ORR activity and stability.