Controlled fabrication of core–shell γ-Fe2O3@C–Reduced graphene oxide composites with tunable interfacial structure for highly efficient microwave absorption

The design of a high-performance microwave absorbing material is highly dependent on the synergistic structural design of heterostructure and the appropriate material compositions. Herein, a series of composites of reduced graphene oxide (RGO) and core-shell structured γ-Fe2O3@C nanoparticles have been achieved by a hydrothermal and in-situ chemical vapor deposition (CVD) method. In particular, the structure of the carbon layer, including its graphitization and thickness, can be controlled by optimizing the CVD conditions, which is beneficial to tailor the impedance matching and dielectric loss. The rationally designed RGO/γ-Fe2O3@C composite has multiple electromagnetic dissipation mechanisms. The effective absorption ranges of an optimal sample at a filling rate of 20% can cover 100% X-band and 98% Ku-band at thicknesses of 3.0 mm and 2.2 mm, respectively. This finding suggested that the controllable fabrication of core-shell heterostructures could be viable approach to upgrade the microwave absorption performance of transition metal oxides.