Coupling atomically ordered PtCo catalysts with ultrathin nitrogen-doped carbon shell for enhanced oxygen reduction

Atomically ordered intermetallic catalysts have great potential for catalyzing efficient oxygen reduction reaction (ORR), while the coupling of metal and support are not emphasized enough. Herein, we report an atomically ordered PtCo bimetallic catalyst coupled with N-doped ultrathin carbon shells (PtCo/NCS) for ORR by a facile natural ligand annealing strategy. The formed NCS prevents the high-temperature sintering of catalysts by physical confinement, and the coupling effect results in a stronger affinity between PtCo and NCS for PtCo/NCS. The optimal PtCo/NCS-5 exhibits more exceptional activity and durability, outperforming commercial Pt/C and Pt3Co/C catalysts (C-Pt3Co/C). It is proved that PtCo and NCS synergically account for the enhanced ORR performance for PtCo/NCS-5. More importantly, the compressive lattice strain effectively promotes electron redistribution and optimizes the electronic structure for PtCo/NCS-5. This work further deepens the understanding of catalytic mechanisms and provides new insight into the rational design of advanced electrocatalysts toward ORR.