Physics

Geology

Nanotechnology

Electrode

Electrocatalyst

Oceanography

Oxygen evolution

Engineering

Catalysis

Physical chemistry

Overpotential

Power (physics)

Chemistry

Metallurgy

Materials science

Substrate (aquarium)

Cobalt oxide

Oxide

Graphene

Bifunctional

Battery (electricity)

Quantum mechanics

Chemical engineering

Cobalt

Electrochemistry

Biochemistry

Advanced Materials

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 (CoOx ) 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 CoOx 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 CoOx 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-2 for OER. The flexible Zn-air battery built with this catalyst exhibits an ultrahigh specific power of 300 W gcat-1 , which is essential for portable devices. This work provides a new design pathway for electrocatalysts for high-performance rechargeable metal-air battery systems.

Ultrathin Cobalt Oxide Layers as Electrocatalysts for High‐Performance Flexible Zn–Air Batteries