Template‐Free Formation of Uniform Fe₃O₄ Hollow Nanoflowers Supported on Reduced Graphene Oxide and Their Excellent Microwave Absorption Performances

Abstract

Iron oxides (Fe2O3, Fe3O4) are highly desirable for electromagnetic (EM) microwave absorption applications because of their high magnetization, low toxicity and good magnetic loss. Herein, we repot an effective strategy to improve the reflection loss (RL) of iron oxides‐based materials via a delicate design of distinctive hybrid nanostructures, where uniform magnetite (Fe3O4) hollow nanoflowers organized from ultrathin nanosheets are supported on the reduced graphene oxide (rGO) matrix (MHF‐rGO). The designed MHF‐rGO exhibits excellent microwave absorption performance with a low RL of −53.3 dB at 4.96 GHz and a wide bandwidth of 5.68 GHz (< − 10 dB). The top level microwave absorption properties are associated with the high surface areas, ultrathin nanosheets and hollow structures of magnetic Fe3O4 nanoflowers, which present a good synergetic role with lightweight rGO. Furthermore, the controllable permittivity in MHF‐rGO is developed by adjusting the rGO content, which can balance the permeability to obtain a good impedance matching. This study paves an effective way to improve and extend the microwave absorption performances of iron oxides‐based materials through a delicate hybrid nanostructures design strategy.

Fe3O4 Nanoflower-Carbon Nanotube Composites for Microwave Shielding

“…Figure is the schematic illustration of the synthesis process of heterogeneous architecture Fe 3 O 4 nanoflower/CNTs composite. The growth of the Fe 3 O 4 nanoflower/CNTs composites mainly includes the following three steps: (i) The absorption of iron ions on CNTs via the electrostatic effects between iron ions and abundant oxygen-containing groups, accompanied by the formation of iron alkoxide in the EG system; (ii) Nucleation and growth into the primary nanoparticles; (iii) Aggregation of the particles to form nanosphere and growth into a flower-like structure. In this designed Fe 3 O 4 nanoflower/CNTs structure, CNTs not only acted as a backbone matrix to uphold the structural integrity of the network, but also acted as a dielectric material to balance the magnetic loss of the composites .…”

“…Fe 3 O 4 nanoflower are constructed from many ultrathin nanosheets (Figure a). In addition, the middle part of the nanoflower is hollow because of the Ostwald ripening occurring during hydrothermal process. , Notably, the Fe 3 O 4 nanoflower can remain the structure very well after adding CNTs, implying the high chemical stability of nanoflower (Figure b–d). Clearly, one-dimensional CNTs tightly envelop the nanoflower to form a good conductive network, which greatly improves the electrical conductivity, increases the interface, and reduces the density of the composites.…”

“…Synthesis of Flowerlike Fe 3 O 4 Nanosphere. As we have previously reported, 24 a simple solvothermal process was applied to prepare the flower-like iron oxide nanosphere. The main process is as follows.…”

Facile Synthesis of Hollow ZnxFe3–xO4@Porous MnO2/rGO Conductive Network Composites for Tunable Electromagnetic Wave Absorption

“…As we all know, for a electromagnetic wave absorption material, the good impedance matching can make incident waves pass into the material as much as possible, as well as the strong attenuation can effectively dissipate electromagnetic waves into heat energy or other forms of energy . The characteristic impedance values of rGO/hollow Zn x Fe 3– x O 4 @porous MnO 2 composites (Figure a) are calculated according to the following equation: …”

Preparation and Characterization of Copper Chromium Oxide Nanoparticles Using Modified Sol‐Gel Route and Evaluation of Their Microwave Absorption Properties

“…Thus, polyaniline, SiC, polypyrrole, polythiophene, and carbon nanotube due to the dielectric properties and magnetic materials such as spinel ferrites_ENREF_16, hexagonal ferrites, Fe 0 , Co, and Ni have attracted considerable attentions. Among the dielectric materials, the 2D structures including graphene, MXenes, and graphite‐like carbon nitride play the vital role for microwave absorption and electromagnetic interference shielding. The impedance matching is the vital agent affecting the microwave absorption characteristics, related to the adjustment of the magnetic and dielectric properties of the absorbers .…”