Nickel hydroxide anchored CNT-Co3O4-N-carbon bifunctional catalyst for rechargeable zinc-air batteries

Background: A rechargeable zinc-air battery (RZAB) is a hopeful alternative battery solution to meet the world's ever-increasing energy storage need. Developing a high-performance electrocatalyst is one of the most critical challenges that need to be addressed for the RZAB to fulfill that role.Methods: A Ni(OH)2-CNT-Co3O4/NC catalyst consisting of carbon nanotube (CNT), cobalt oxide, and nitrogen-doped functionalities embedded in a porous carbon framework with two-dimensional Ni(OH)2 nanosheets is reported.Significant findings: The prepared catalytic material, Ni(OH)2-CNT-Co3O4/NC, showed a high limit current density of-6.409 mA cm-2 during the oxygen reduction reaction (ORR), surpassing that of the commercial Pt/C (-5.625 mA cm-2). The oxygen evolution reaction (OER) potential for this electrocatalyst also reached 1.653 V at a current density of 10 mA cm-2, which is close to that of the commercial RuO2 and thus showed excellent cat-alytic activity for the OER. As a bifunctional catalyst in the RZAB, the Ni(OH)2-CNT-Co3O4/NC electrocatalyst exhibited a high power density of 244.5 mW cm-2, and cycled 4500 times at a current density of 10 mA cm-2 while displaying good charge and discharge stability. Based upon these performances, we believe that the Ni (OH)2-CNT-Co3O4/NC catalyst can serve as an excellent bifunctional catalyst in the next-generation RZAB.