Self-Constructed Interface of Co2P/Co3Fe7 Nanoparticles Encapsulated in N-Doped Carbon Nanotubes as Superior Bifunctional Oxygen Electrocatalysts for Rechargeable Zn-Air Batteries

Abstract Designing interfacial structure is an essential but challenging approach to regulating electronic structures to develop favorable bifunctional oxygen electrocatalysts in Zn-air batteries (ZABs). We utilize a facile one-step sintering strategy for preparing Co 2 P/Co 3 Fe 7 interfacial nanoparticles encapsulated in N-doped carbon nanotubes (Co 2 P/Co 3 Fe 7 @N-C). The obtained Co 2 P/Co 3 Fe 7 @N-C electrocatalyst exhibits significant bifunctional oxygen evolution/reduction reaction (OER/ORR) activity (Δ E = 0.61 V), better than that of Pt/C + Ir/C (Δ E = 0.69 V) and compete with other previously report electrocatalysts. The density functional theory results reveal that the synergistic coupling effect and interfacial electronic interaction between Co 2 P and Co 3 Fe 7 play a key role in boosting bifunctional ORR/OER efficiency. Remarkably, Co 2 P/Co 3 Fe 7 @N-C-based liquid ZABs exhibit excellent performance with higher power density (152.3 mW cm − 2 ) and longer cycle stability (1596 cycles) than the Pt/C + Ir/C-based ZABs (105 mW cm − 2 ; 882 cycles). Interestingly, the connected in series of Co 2 P/Co 3 Fe 7 @N-C-based liquid ZABs can be powered emitting diodes (LEDs) and blue LEDs display panel, indicating the possibility of practical application. It can be predicted that our present work opens a new pathway for rationally designing superior bifunctional oxygen electrocatalysts for rechargeable metal-air batteries through interfacial engineering.