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 2 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 2 nanoparticles are synthesized as the catalyst. The electron transfer from the metallic Co to ZrO 2 causes interface-oriented electron enrichment that promotes the activation and conversion of O 2 , improving the efficiency of 4e - transfer. Moreover, the simulation results show that ZrO 2 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 1/2 ) 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 1/2 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.