Abstract
Nitrogen-doped graphene (NG)/SnO2 hollow sphere hybrids were synthesized in this work. The chemical composition, crystal structure and morphology have been characterized by FT-IR spectra, XRD, Raman spectra, XPS, SEM and TEM in detail. Reflection loss (RL) values of NG/SnO2 hollow sphere hybrids less than −10 dB and −20 dB are found in the wide frequency range of 4.5–18 GHz and 5–16.2 GHz within 1.3–3.5 mm, and a minimum RL of −50.3 dB is achieved at 8.6 GHz with the matching thickness of only 2.3 mm. The results indicate that the NG/SnO2 hollow sphere hybrids with high-performance microwave absorption properties have a promising future in decreasing electromagnetic wave irradiation and interference.
Highlights
IntroductionHollow structures exhibit special physical and chemical properties due to their low density and large surface area, having attracted attention as candidates for microwave absorption in recent years.[29,30,31] Zhao et al prepared the hollow three-dimensional CuS hierarchical microspheres and the effective bandwidth was 3.0 GHz with absorber thickness of 1.1 mm.[32]
Amino-function SnO2 hollow spheres anchored on the Graphene oxide (GO) sheets surface through electrostatic interaction and the Nitrogen-doped graphene (NG)/SnO2 hollow spheres hybrids were prepared by using a hydrothermal method with urea as the nitrogen source and reducing agent
The characteristic features of GO are the adsorption bands corresponding to the C]O stretching vibration at 1723 cmÀ1, corresponds to the graphite-like sp2 C (C]C) deformation vibration at 1613 cmÀ1, C– OH stretching at 1226 cmÀ1 and C–O stretching at 1053 cmÀ1, indicating that abundant oxygen functional groups (–COOH, –OH) were introduced during the exfoliation of the graphene sheet.[2]
Summary
Hollow structures exhibit special physical and chemical properties due to their low density and large surface area, having attracted attention as candidates for microwave absorption in recent years.[29,30,31] Zhao et al prepared the hollow three-dimensional CuS hierarchical microspheres and the effective bandwidth was 3.0 GHz with absorber thickness of 1.1 mm.[32]. Han et al synthesized the graphene-wrapped ZnO hollow spheres and a maximum absorption of À45.05 dB at 9.7 GHz with the thickness of 2.2 mm.[33] Fu et al prepared CoFe2O4 hollow spheres/graphene composites and a minimum re ection loss of À18.5 dB was observed at 12.9 GHz with a thickness of 2 mm and the effective absorption frequency range from 11.3 to 15.0 GHz.[34]. Have been studied and obtained good microwave absorption properties.[37,38,39] The composites with SnO2 decorated on graphene sheets have been used for supercapacitor application and microbial fuel cells.[42,43] So far, the EM absorption properties of N-doped graphene/SnO2 hollow spheres hybrids have not been studied. The high performance EM absorbing mechanism of the NG/SnO2 hollow spheres hybrids is further discussed
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