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 hy-drothermal 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 re-quirements 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.