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Confined growth of porous nitrogen-doped cobalt oxide nanoarrays as bifunctional oxygen electrocatalysts for rechargeable zinc-air batteries

: Wang, Xia; Liao, Zhongquan; Fu, Yubin; Neumann, Christof; Turchanin, Andrey A.; Nam, Gyutae; Zschech, Ehrenfried; Cho, Jaephil; Zhang, Jian; Feng, Xinliang


Energy storage materials 26 (2020), S.157-164
ISSN: 2405-8297
European Commission EC
H2020; 785219; GrapheneCore2
Graphene Flagship Core Project 2
German Excellence Initiative
Cluster of Excellence; EXC1056
National Natural Science Foundation of China NSFC
Deutsche Forschungsgemeinschaft DFG
TRR 234
Fraunhofer IKTS ()
zinc-air battery; flexible electrode; bifunctional electrocatalyst; nitrogen doping; porous cobalt oxide

Cobalt oxides are promising bifunctional oxygen electrocatalysts due to their intrinsic activities toward both dissociation and formation of oxygen molecules. Unfortunately, their practical utilization is seriously hindered by the limited accessible active sites and inferior activity. Herein, vertically-aligned porous nanoarrays composed of ultrafine nitrogen-doped cobalt oxide (NP-Co3O4) nanoparticles (4-5 ​nm) are in-situ fabricated on carbon cloth (CC) via mild oxidation of Co-based zeolitic-imidazolate-framework (Co-ZIF) nanoarrays. The oxidation decomposition of 2-methylimidazolate ligands between Co nodes not only confines the growth of cobalt oxides, but also provides the nitrogen sources for realizing low-temperature (200 ​°C) nitrogen doping. In alkaline electrolyte, the as-built NP-Co3O4/CC manifests an extremely high oxygen reduction reaction (ORR) half-wave potential of ~0.9 ​V and a decreased oxygen evolution reaction (OER) overpotential of 330 ​mV ​at 10 ​mA ​cm−2, displaying a record low potential gap of 0.66 ​V. As bifunctional oxygen electrodes in rechargeable aqueous and all-solid-state flexible zinc-air batteries, the NP-Co3O4/CC-based batteries exhibit ultrahigh power densities up to 200 ​mW ​cm−2 and 99.8 ​mW ​cm−3, respectively, which are much higher than those of reported bifunctional oxygen electrocatalysts. This work paves a new avenue for the fabrication of porous nitrogen doped metal oxides towards high-performance zinc-air batteries.