Heterostructure and Oxygen Vacancies Promote NiFe2O4/Ni3S4 toward Oxygen Evolution Reaction and Zn‐Air Batteries

Abstract Developing high‐performance catalysts for oxygen evolution reaction (OER) is critical for the widespread applications of clean and sustainable energy through electrochemical devices such as zinc‐air batteries and (photo)electrochemical water splitting. Constructing heterostructure and oxygen vacancies have demonstrated great promises to boost the OER performance. Herein, we report a facile strategy to fabricate hetero‐structured NiFe2O4/Ni3S4 nanorods, where NiFe2O4 can be derived from Fe‐based metal‐organic frameworks (MOFs). The NiFe2O4/Ni3S4 catalyst exhibited excellent OER performance, evidenced by an overpotential value of 357 mV at the current density of 20 mA cm−2, and a small Tafel slope of 87.46 mV dec−1 in 1 M KOH, superior to the benchmark IrO2 catalyst. Moreover, NiFe2O4/Ni3S4 outperformed with regard to long‐term durability for OER than IrO2. Such outstanding OER performance is mainly accounted by the interface between NiFe2O4 and Ni3S4, and the presence of rich oxygen vacancies. When employed as air‐cathode in zinc‐air batteries, the NiFe2O4/Ni3S4 decorated battery had a high round‐trip efficiency of 62.1% at 10 h, and possessed long‐term stability of >50 h. This study may pave the way for fabricating non‐noble‐metal‐based cost‐effective, efficient and durable electrocatalysts for OER, zinc‐air batteries, and beyond.