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.