Fe2NiO4/FeNiS2 heterostructure-assembled hollow microtubes with numerous intimate interfaces as advanced catalyst for Zn–Air battery

An efficient electrocatalyst based on hollow-structured microtubes assembled by Fe2NiO4/FeNiS2 hetero-structured nanosheets is developed for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as two-half electrochemical reactions at air cathode of the zinc–air battery. The Fe2NiO4/FeNiS2 nanosheets with strong interaction between Fe2NiO4 and FeNiS2 at the heterointerface can tailor the electronic structure towards boosting the catalytic activity. In addition, the hollow structure effectively reduces the charge/mass transfer resistance, while providing a large surface area. Therefore, the bifunctional activity of the proposed catalyst for both the ORR and OER approaches that of the Pt/C and surpasses that of the RuO2. The zinc–air battery with our material as air–cathodic material possesses a desirable power density of 144.22 mW cm−2 and superior cycling performance of over 1,500 cycles (40 min per cycle) at high current density of 2.0 mA cm−2, outperforming almost the latest reports in the literature.