| Abstract | Developing low-cost non-precious metal catalysts for high-performance oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly desirable. In this work, both the primary and rechargeable Zn–air batteries with NiCo₂O₄ nanosphere and carbon nanotubes hybrid (NiCo₂O₄-CNTs) as cathode catalyst are reported. The catalysts are synthesized through a facile one-pot precipitation reaction and hydrothermal process, which exhibited highly active bi-functional catalytic activity for both ORR and OER. Using NiCo₂O₄-CNTs hybrid as a cathode catalyst, the resulting practical primary and electrochemically rechargeable Zn–air batteries give a promising discharge peak power density as high as 320 mW cm₋₂, and a high current density 210 mA cm⁻² at 1.0 V. Also, the rechargeable Zn–air batteries in a two-electrode configuration exhibits an unprecedented small charge–discharge voltage polarization of ∼0.75 V at 10 mA cm⁻², high reversibility and stability over long charge and discharge cycles. The high performance is believed to be induced by the hybrid effect (coupling effect) among NiCo₂O₄ nanosphere and CNTs, which can produce a synergy enhancement for both catalytic ORR and OER. |
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