Plasma-Engraved Lattice-Matched NiO/NiFe2O4 Heterostructure with Ample Oxygen Vacancies for Efficient Water Electrolysis and Zn-Air Batteries

Abstract

Heterogeneous interface and defect engineering offer effective pathways to accelerate oxygen evolution reaction (OER) charge transfer kinetics and motivate optimal intrinsic catalytic activity. Herein, we report the lattice-matched NiO/NiFe₂O₄ heterostructure with ample oxygen vacancies (Vo-NiO/NiFe₂O₄) induced by a feasible hydrothermal followed by calcination and plasma-engraving assistant technique, which shows the unique porous microflower arrangement of intertwined nanosheets. Benefitting from the synergetic effects between lattice-matched heterointerface and oxygen vacancies induce the strong electronic coupling, optimized OH⁻/O₂ diffusion pathway and ample active sites, thus-prepared Vo-NiO/NiFe₂O₄ presents a favorable OER performance with a low overpotential (261 mV @ 10 mA cm⁻²) and small Tafel slope (39.4 mV dec⁻¹), even surpassing commercial RuO₂ catalyst. Additionally, the two-electrode configuration water electrolyzer and rechargeable zinc-air battery assembled by Vo-NiO/NiFe₂O₄ catalyst show the potential practical application directions. This work provides an innovative avenue for strengthening OER performance toward water electrolysis and Zn-air batteries via the interface and vacancy engineering strategy.