The Contact Interface Electronic Coupling of Cobalt and Zirconia Enables Stable and Highly Efficient 4e Oxygen Reduction Reaction Catalysis.

Cobalt (Co) is an efficient oxygen reduction reaction (ORR) catalyst but suffers from issues of easy deactivation and instability. Here, it shows that ZrO can stabilize Co through interface electron coupling and enables highly efficient 4e ORR catalysis. Porous carbon nanofibers loaded with dispersed Co-nanodots (≈10 nm, 9.63 wt%) and ZrO nanoparticles are synthesized as the catalyst. The electron transfer from the metallic Co to ZrO causes interface-oriented electron enrichment that promotes the activation and conversion of O, improving the efficiency of 4e transfer. Moreover, the simulation results show that ZrO acts like an electron reservoir to store electrons from Co and slowly release them to the interface, solving the easy deactivation problem of Co. The catalyst exhibits a high half-wave potential (E) of 0.84 V, which only decreases by 3.6 mV after 10 000 cycles, showing great stability. Particularly, the enhanced spin polarization of Co in a magnetic field reinforces the interface electron coupling that increases the E to 0.864 V and decreases the energy barrier of ORR from 0.81 to 0.63 eV, confirming that the proposed strategy is effective for constructing efficient and stable ORR catalysts.