Magnetic NiFe2O4@FeNi3 core-shell nanospheres derived from FeNi-LDH precursor anchoring on rGO nanosheets for enhanced electromagnetic wave absorption

Graphene has been extensively utilized in the domain of electromagnetic wave (EMW) absorption materials because of its excellent electrical conductivity. However, the inferior impedance matching performance and the single loss mechanism vastly restrict the application. Hence, it's an effective strategy to solve these issues by introducing magnetic components. Notably, layer double hydroxide (LDH) is an appropriate template to obtain magnetic component materials. Considering that ferromagnetic metals such as Fe, Co, Ni, and their corresponding metal oxides are usually treated as magnetic components which are promising candidates for EMW absorption materials. Therefore, in this work, a FeNi-layered double hydroxide-reduced graphene oxide (FeNi-LDH-rGO) aerogel was synthesized through a series of processes such as electrostatic self-assembly, hydrothermal, freeze-drying, and annealing. The magnetic NiFe2O4@FeNi3 core-shell nanospheres were obtained from FeNi-LDH precursor, anchoring on rGO nanosheets after the annealing treatment. Furthermore, the effects of different mass ratios of LDH to GO as well as different annealing temperatures of LDH-rGO aerogel on the EMW absorption property and impedance matching performance were explored. As a consequence, the fabricated ultralight 600LDH-rGO 2:1 aerogel shows a broad effective absorption bandwidth (EAB) of 7.04 GHz at a thickness of 2.3 mm with a low filling content of only 6 wt% and a low density of 4.4 mg/cm3. In conclusion, the synthetic LDH-rGO aerogels offer an effective strategy for preparing EMW absorption materials that own three-dimensional porous network structure and unique magnetic NiFe2O4@FeNi3 core-shell structure nanospheres.