Interfacing spinel NiCo2O4 and NiCo alloy derived N-doped carbon nanotubes for enhanced oxygen electrocatalysis

The active sites on oxygen electrocatalyst and the number of inherent active species are important factors affecting the performance of Zn-air battery. Constructing multiphase interfaces is an effective strategy to increase the number of active species for oxygen electrocatalysts. In this work, the number of intrinsic active species of spinel oxygen electrocatalyst was increased and its catalytic activity was enhanced by the synergistic action of bimetallic center three interfaces and heteroatom-doped carbon nanostructures. The resulting NiCo2O4/NCNTs/NiCo as catalyst exhibits superior activity toward ORR (E-1/2 = 0.83 V, J(L) = 5.38 mA cm(-2)) and OER (E-j10 = 1.58 V). Further, the obtained catalyst work as a cathode assembles as Zn-air battery with a high open-circuit potential of 1.51 V and excellent cycle stability (586 h). Theoretical results indicate that the desorption of *OH species is the rate-determining step for ORR, the multiphase interfaces in the NiCo2O4/NCNTs/NiCo will provide additional electrons due to the upward shift of antibonding orbitals relative to the Fermi level. Consequently, it boosts the oxygen adsorption and charge transfer and accelerate the reaction kinetics. This work emphasizes the synergistic effect between multiphase interfaces in transition metal composite catalysts and opens up a promising way for the preparation of efficient and stable transition metal electrocatalysts.

Automated summary

By constructing multiphase interfaces, the number of active species on oxygen electrocatalysts was increased, improving catalytic activity for oxygen reduction and oxygen evolution reactions. The resulting catalyst showed superior performance in Zn-air battery, highlighting the synergistic effect between multiphase interfaces in transition metal composite catalysts. This work provides a promising strategy for preparing efficient and stable transition metal electrocatalysts.