Multimetallic electrocatalysts of FeCoNi nanoalloy embedded in multilayered carbon nanotubes for oxygen reduction reaction and flexible Zn-air battery

A series of multicomponent electrocatalysts comprising trimetallic transitional alloy and nanoparticles embedded within multilayered-carbon nanotubes (FeCoNi-CNTs) have been prepared by pyrolysis of the complexes of melamine and Co2+/Ni2+/Fe3+ salts at different ratios under N2 atmosphere. Combining diverse characterizations of the series of FeCoNi-CNTs revealed that multiple metal modes such as metallic species (Fe, Co, and Ni), M−N, M−O, and FeCoNi alloy are coexisted and evenly distributed in the carbon matrix. The control experiments and DFT calculations verified integration of superior electrocatalytic abilities of these metal active sites and enhanced conductivity of multilayered CNTs endowed the developed electrocatalysts with outperformed catalytic properties. When used FeCoNi-CNTs-2 catalyst (gained by adding 0.2 g transition metal salts and calcined at 700 °C) as electrode, the assembling Zn-air battery (ZAB) delivered a stable open circuit potential of 1.49 V, a high power density of 210.5 mW cm−2 and specific capacity of 815.5 mA h gZn-1 at 10 mA cm−2. The ZAB performances were higher than most reported metal compound-based electrocatalysts. Especially, the constructed solid ZAB exhibited high flexibility and showed a wide application potential as electron devices.