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Ultrathin Co3O4 Nanofilm as an Efficient Bifunctional Catalyst for Oxygen Evolution and Reduction Reaction in Rechargeable Zinc-Air Batteries

Abstract

Two-dimensional (2D) nanocatalysts with large specific surface area and efficient charge conductivity are promising candidates for catalyzing sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which are at the heart of various electrochemical energy conversion and storage technologies. Herein, we report the synthesis of ultrathin Co3O4 nanofilm with thickness of nearly 1.8 nm via a surfactant and template-free facile hydrothermal route. The proposed synthesis strategy can be extended to the preparation of 2D NixCo3-xO4 and FexCo3-xO4 nanostructures. The synthesized Co3O4 nanofilm exhibits a superior bifunctional activity than the counterpart Co3O4 nanoparticles including lower overpotential and larger reduction or evolution current densities, demonstrating a faster catalytic kinetics over 2D nanofilm surface. Compared to precious metal-based catalysts, to achieve an OER current density of 40 mA cm−2, the overpotential of nanofilm (461 mV) is lower than that of RuO2 (526 mV) while the ORR on nanofilm proceeds through a dominant 4e- transfer mechanism, which is similar to the commercial carbon supported Pt (Pt/C). The Co3O4 nanofilms enable assembled rechargeable Zn-air batteries with lower overpotential (0.72 V), higher round-trip efficiency (62.7 %), and longer cycle lifetime (175 cycles). The remarkable bifunctional activity contributes to the increased number of electrochemically active sites, high interfacial contact area with the electrolyte, and the enrichment of Co3+ on the surface, which facilitates the adsorption and activation of oxygen-containing species. This study should shed light on the future development of new electroactive materials with optimized 2D nanostructures to enhance the overall bifunctional ORR/OER performance for rechargeable metal-air batteries.

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Publication details

The article was accepted on 05 May 2017 and first published on 12 May 2017


Article type: Paper
DOI: 10.1039/C7NR02385E
Citation: Nanoscale, 2017, Accepted Manuscript
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    Ultrathin Co3O4 Nanofilm as an Efficient Bifunctional Catalyst for Oxygen Evolution and Reduction Reaction in Rechargeable Zinc-Air Batteries

    Y. He, J. Zhang, G. He, X. Han, X. Zheng, C. Zhong, W. Hu and Y. Deng, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR02385E

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