Tailored architectures of FeNi alloy embedded in N-doped carbon as bifunctional oxygen electrocatalyst for rechargeable Zinc-air battery.

As one type of bifunctional oxygen electrocatalyst for Zn-air battery, herein, FeNi alloy was successfully embedded into N-doped carbon with tailored architectures by integrating MOF precursor method and polymer coating/encapsulation strategy. The content of Fe in primary precursor has been proven to be able to obviously affect the morphology of the final catalyst. Benefiting from the mature active site (e.g. FeNi alloy) and the stable carbon matrix, a series of catalysts exhibited good performance towards ORR and OER. Of great significance, a particular ratio of Fe/Ni happened to be able to catalyze the growth of 1D bamboo-like carbon nanotubes, giving rise to a conductive network to diffuse ORR/OER-relevant species. Apparently, a low discharge-charge voltage gap (1.1 V) was acquired in a liquid Zn-air battery with 1.5FeNi@NCNT air cathode. Moreover, the solid-state Zn-air battery assembled on it also displayed a high open circuit voltage (1.38 V) and yielded a high power density of 81 mW cm-2 at 0.83 V. This would leverage a choice to tailor carbon geometry of FeNi alloy-based active sites for ORR/OER and further serve for devices of practical significance.