Ultrathin Cobalt Oxide Layers as Electrocatalysts for High-Performance Flexible Zn-Air Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 30785222.
- Also identified by DOI 10.1002/adma.201807468.
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Abstract
Synergistic improvements in the electrical conductivity and catalytic activity for the oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) are of paramount importance for rechargeable metal-air batteries. In this study, one-nanometer-scale ultrathin cobalt oxide (CoO<sub>x</sub> ) layers are fabricated on a conducting substrate (i.e., a metallic Co/N-doped graphene substrate) to achieve superior bifunctional activity in both the ORR and OER and ultrahigh output power for flexible Zn-air batteries. Specifically, at the atomic scale, the ultrathin CoO<sub>x</sub> layers effectively accelerate electron conduction and provide abundant active sites. X-ray absorption spectroscopy reveals that the metallic Co/N-doped graphene substrate contributes to electron transfer toward the ultrathin CoO<sub>x</sub> layer, which is beneficial for the electrocatalytic process. The as-obtained electrocatalyst exhibits ultrahigh electrochemical activity with a positive half-wave potential of 0.896 V for ORR and a low overpotential of 370 mV at 10 mA cm<sup>-2</sup> for OER. The flexible Zn-air battery built with this catalyst exhibits an ultrahigh specific power of 300 W g<sub>cat</sub> <sup>-1</sup> , which is essential for portable devices. This work provides a new design pathway for electrocatalysts for high-performance rechargeable metal-air battery systems.