Size-controllable porous flower-like NiCo₂O₄ fabricated via sodium tartrate assisted hydrothermal synthesis for lightweight electromagnetic absorber

Although the performance of NiCo₂O₄-based absorbers with multiple components has made great progress, the property of pure NiCo₂O₄ is still far from the requirements of high-performance electromagnetic wave absorbers. It is recognized that morphology control is an effective strategy to improve electromagnetic absorbing capacity of absorbers. Herein, this work reported the fabrication of porous flower-like pure NiCo₂O ₄ via simple hydrothermal reaction with the assistant of sodium tartarate in where tartaric acid served as a structure-directing agent. It was demonstrated that size distribution and electromagnetic absorbing capacity of the obtained NiCo₂O₄ could be modulated easily by controlling addition of sodium tartrate. It was verified that dipole polarization originated from lattice defect and oxygen vacancy as well as interfacial polarization ascribing to adjacent and interconnected flakes are responsible for the excellent electromagnetic absorbing performance. The obtained porous flower-like NiCo₂O₄ exhibited broad absorption bandwidth at thin thickness as well as proper dissipation ability. This work offers a new strategy to fabricate size-controllable porous flower-like NiCo₂O₄ electromagnetic absorber. It is believed the obtained NiCo₂O₄ will be a promising candidate as a lightweight electromagnetic absorbing material.