Constructing magnetic iron-based core-shell structure and dielectric nitrogen-doped reduced graphene oxide nanocomposite for enhanced microwave absorption performance

A ferromagnetic nanocomposite Fe3O4@Fe/Fe4N/CFe15.1-NrGO, which is composed of elemental iron-based, iron nitride-based and iron carbide-coated ferroferric oxide core-shell structured nanospheres and nitrogen-doped partially-reduced graphene oxide (NrGO), has been successfully prepared by combining an initial hydrothermal processing, subsequent reducing agent impregnation and final solid-state thermal reduction. And then, we investigate the microwave absorption performance of Fe3O4@Fe/Fe4N/CFe15.1-NrGO nanocomposite in paraffin dispersion. When the loading mass of Fe3O4@Fe/Fe4N/CFe15.1-NrGO is 9.0 wt% in paraffin dispersion, the minimum reflection loss (RLmin) of microwave is as high as −30.5 dB at the thickness of 1.5 mm, and the corresponding effective absorption bandwidth (EAB < -10 dB) of 4.4 GHz (13.6 ∼ 18.0 GHz) is the 27.5% of the entirely measuring bandwidth from (2.0 ∼ 18.0 GHz). The excellent microwave absorbing performances of nanocomposite Fe3O4@Fe/Fe4N/CFe15.1-NrGO may be attributed to the following twoaspects: (i) the interfacial polarization of the core-shell structure of spheroidal iron-based constituents and the interface between an iron-based nanosphere and dielectric lamellar NrGO and (ii) a synergistic effect between dielectric properties of lamellar-structured NrGO and the magnetic properties of core-sell structured Fe3O4@Fe/Fe4N/CFe15.1. This electromagnetic absorber with core-shell structure and dielectric graphene properties can satisfy the requirements of ideal absorbers, such as strong absorption ability, broad absorption bandwidth, thin absorber thickness and low density. In addition, this work also provides a promising strategy to synthesize multivariate two-dimensional nanocomposite with light-weight and high absorption performance.