Co_(3)O_(4)/Mn_(3)O_(4) hybrid catalysts with heterointerfaces as bifunctional catalysts for Zn-air batteries

Zinc-air batteries(ZABs) with high energy density and safety are promising as next-generation energy storage systems, while their applications are severely hindered by the sluggish reaction kinetic of air cathodes. Developing a bifunctional catalyst with high activity and durability is an effective strategy to address the above challenges. Herein, a Co_(3)O_(4)/Mn_(3)O_(4) nanohybrid with heterointerfaces is designed as advanced cathode catalyst for ZABs. Density functional theory calculations show the heterogeneous interface between Co_(3)O_(4)/Mn_(3)O_(4) can improve the dynamics of carrier transport and thus enhancing the catalytic activity and durability. The Co_(3)O_(4)/Mn_(3)O_(4) catalyst anchored on reduced graphene oxide(rGO)exhibits high oxygen reduction reaction(ORR) activity with a half-wave potential of 0.86 V, and excellent oxygen evolution reaction(OER) activity with the potential of 1.59 V at 10 mA cm^(-2) , which are comparable to the commercial noble metal catalysts. The improved ORR/OER catalytic activity is ascribed to the synergistic effect of heterointerfaces between Co_(3)O_(4) and Mn_(3)O_(4)as well as the improved conductivity and contact area of oxygen/catalysts/electrolytes three-phase interface by r GO. Furthermore, a home-made ZAB based on Co_(3)O_(4)/Mn_(3)O_(4)/r GO shows a high open circuit voltage of 1.54 V, a large power density of 194.6 mW cm^(-2) and good long-term cycling stability of nearly 400 h at 5 mA cm^(-2) , which affords a promising bifunctional oxygen catalyst for rechargeable ZABs.