Nanotechnology

Organic chemistry

Bifunctional catalyst

Zinc

Composite number

Engineering

Catalysis

Carbon fibers

Nanoparticle

Composite material

Inorganic chemistry

Chemistry

Metallurgy

Materials science

Bifunctional

Chemical engineering

Optoelectronics

Cobalt

Nitrogen

Doping

Angewandte Chemie International Edition

Low-cost, efficient bifunctional electrocatalysts are needed to mediate the oxygen reduction and oxygen evolution reactions (ORR/OER) in Zn-air batteries. Such catalysts should offer binary active sites and an ability to transfer oxygen-based species and electrons. A 3D catalyst, composed of nanoparticles of CoFe alloy embedded in N-doped carbon nanotubes tangled with reduced graphene oxide, was developed, which presents appreciable ORR/OER activity when applied in a Zn-air battery. A high open-circuit voltage of 1.43 V, a stable discharge voltage of 1.22 V, a high energy efficiency of 60.1 %, and excellent stability after 1 600 cycles at 10 mA cm-2 are demonstrated. An all-solid-state battery had an outstanding lifetime and high cell efficiency even upon bending. In situ X-ray absorption spectroscopy revealed that OOH* and O* intermediates induce variations in the Fe-Fe and Co-Co bond lengths, respectively, suggesting that Fe and Co species are crucial to the ORR/OER processes.

A Stable Bifunctional Catalyst for Rechargeable Zinc–Air Batteries: Iron–Cobalt Nanoparticles Embedded in a Nitrogen‐Doped 3D Carbon Matrix