Hollow iron carbides via nanoscale Kirkendall cavitation process for zinc-air batteries

Hollow structured nanoparticles, especially metal carbides, are of great interest because of their wide applications, unique morphologies and superior catalytic properties. The Kirkendall cavitation process is a typical method of producing hollow structured nanoparticles. It should be noted that only precursors with proper diffusion couples can guarantee a successful preparation. In this work, based on a matching diffusion rate of graphene with that of iron atoms, hollow iron carbides nanoparticles anchoring on N-doped reduced graphene oxides (hollow Fe₃C/N-rGO) are designed via a simple carbonization synthesis method. As expected, the obtained Fe₃C/N-rGO exhibits excellent electrocatalytic performance both in oxygen reduction (E_1/2 = 0.829 V) and evolution reactions. Rechargeable Zn-air batteries are assembled based on the composite, which can also deliver a notable peak power density (160.2 mW cm⁻²), long cycle life (over 300 cycles) and deformable property.