Facile synthesis of NiCo\u2082O\u2084 nanosphere-carbon nanotubes hybrid as an efficient bifunctional electrocatalyst for rechargeable Zn\u2013air batteries

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\u2013air batteries with NiCo\u2082O\u2084 nanosphere and carbon nanotubes hybrid (NiCo\u2082O\u2084-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 NiCo\u2082O\u2084-CNTs hybrid as a cathode catalyst, the resulting practical primary and electrochemically rechargeable Zn\u2013air batteries give a promising discharge peak power density as high as 320 mW cm\u207b\ub2, and a high current density 210 mA cm\u207b\ub2 at 1.0 V. Also, the rechargeable Zn\u2013air batteries in a two-electrode configuration exhibits an unprecedented small charge\u2013discharge voltage polarization of 3c0.75 V at 10 mA cm\u207b\ub2, 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 NiCo\u2082O\u2084 and CNTs, which can produce a synergy enhancement for both catalytic ORR and OER.Peer reviewed: YesNRC publication: Ye