Searching for an efficient strategy to prepare highly active and stable electrocatalysts for sluggish oxygen reduction reaction(ORR)is one of the challenges we are facing for the commercialization of fuel cells.Here,we present a facile synthesis of extremely active and stable nitrogen doped carbon-encapsulated PtFe2 intermetallics(denoted as O-PtFe2@NC)as an efficient ORR electrocatalyst via one-step thermal annealing at 800℃(Fig.1a).As shown in Fig.1b.the carbon shells with thickness of 0.6~0.8 nm were in situ formed and the characteristic lattice spacing of 0.186 nm,0.263 nm and 0.115 nm were calculated to identify the ordered structure of OPtFe2@ NC.In Fig.1c,the N-doped carbon layer with some defects can be directly observed.The as synthesized O-PtFe2@NC nanocatalyst also shows relative higher half wave potential than that of D-PtFe2 and Pt(Fig.1d).Moreover,excellent long-term stability with negligible electrochemical activity loss is also observed after accelerated durability test(ADT)in O2-saturated HClO4 solution for 10,000 cycles(Fig.1e-g).The demonstrated strategy via facile one-step high-temperature pyrolysis for obtaining ultrathin N-doped carbon shell encapsulated intermetallic PtFe2 nanoparticles without further treatment may provide a new insight into the preparation of highly durable and active Pt-based catalysts towards the commercialization of Proton exchange membrane fuel cells(PEMFCs).