Facile synthesis of BTA@NiCo₂O₄ hollow structure for excellent microwave absorption and anticorrosion performance

A three-dimensional hollow NiCo₂O₄ structure was successfully prepared with a precipitation-hydrothermal method. A balance between magnetic and dielectric losses was achieved by using a hollow NiCo₂O₄ structure loaded with benzotriazole (BTA), and thus the performance of electromagnetic waves was attenuated. The minimum reflection loss value of BTA@NiCo₂O₄ at 16.01 GHz was -35.39 dB when the absorber thickness was 2 mm, at which the absorption bandwidth for an RL of less than -10 dB is as high as 4.64 GHz. The absorption mechanism was characterized by the synergy among interfacial polarization, multiple reflection, and dipole polarization enhancement between NiCo₂O₄ and BTA. Interestingly, the epoxy/BTA@NiCo₂O₄ coating not only exhibited an outstanding microwave absorption (MA) performance but also has excellent anticorrosion and self-healing properties, as shown by the results of electrochemical impedance spectroscopy and confocal laser scanning microscopy. This work would be very helpful to the development of novel coatings with excellent MA performance and anticorrosion and self-healing properties.