Proton exchange membrane fuel cells convert hydrogen and oxygen into electricity without emissions. The high cost and low durability of Pt-based electrocatalysts for the oxygen reduction reaction hinder their wide application, and the development of non-precious metal electrocatalysts is limited by their low performance. Here we design a hybrid electrocatalyst that consists of atomically dispersed Pt and Fe single atoms and Pt–Fe alloy nanoparticles. Its Pt mass activity is 3.7 times higher than that of commercial Pt/C in a fuel cell. More importantly, the fuel cell with a low Pt loading in the cathode (0.015 mg_Pt cm⁻²) shows an excellent durability, with a 97% activity retention after 100,000 cycles and no noticeable current drop at 0.6 V for over 200 hours. These results highlight the importance of the synergistic effects among active sites in hybrid electrocatalysts and provide an alternative way to design more active and durable low-Pt electrocatalysts for electrochemical devices.

Metal-free phosphorus-doped graphene nanosheets (P-TRG) with large surface area (496.67 m² g⁻¹) and relatively high P-doping level (1.16 at.%) were successfully prepared by thermal annealing a homogenous mixture of graphene oxide and 1-butyl-3-methlyimidazolium hexafluorophosphate under argon atmosphere. It was found that the P atoms were substitutionally incorporated into the carbon framework and were partially oxidized, which created new active sites for the oxygen reduction reaction (ORR). Accordingly, the ORR catalytic performance of the P-doped graphene was demonstrated to be better than or at least comparable to that of the benchmark Pt/C catalyst.