Dual anchoring strategy for preparing Fe single-atom modified Pt nanoparticles as highly stable oxygen reduction electrocatalysts

Developing highly stable and uniformly dispersed Pt nanoparticles (NPs)-based oxygen reduction reaction (ORR) catalysts still remains an extremely difficult task due to the large-scale aggregation and migration of Pt NPs. Herein, a dual anchoring strategy was employed to prepare highly stable Pt NPs loaded uniformly on mesoporous carbon hollow spheres (MCHS) containing Fe single-atom (FeSA) active sites (PtNP-FeSA@MCHS). A combination of the mesoporous structure of MCHS with the electron transfer from Fe single-atom and Pt NPs (so called dual anchoring strategy) enables the Pt NPs anchored and uniformly dispersed over the whole matrix of FeSA@MCHS, endowing PtNP-FeSA@MCHS ultra-high ORR stability, with a decrease in half-wave potential of only 3 mV and the mass activity (MA) as well as specific activity (SA) attenuation of merely 5 % and 2 % after 20,000 cycles of the accelerated durability test (ADT), respectively, surpassing the most of Pt nanoparticles (NPs)-based ORR catalysts reported thus far. In particular, the TEM analysis for PtNP-FeSA@MCHS after the ADT revealed no significant aggregation of Pt NPs, thus showing the superior structural stability of PtNP-FeSA@MCHS. Furthermore, PtNP-FeSA@MCHS shows good activity with MA of 0.63 A mgPt(-1) and SA of 1.22 mA cm(-2), which are 4.5 and 6.8 times of 20 % Pt/C (MA = 0.14 A mg(Pt)(-1) and SA = 0.18 mA cm(-2)), respectively. This dual anchoring strategy provides a foundation for the design of Pt-based ORR catalysts with superior stability and activity.