“…All three materials contain four bands, namely D, G, 2D, and D + G, with a slight change in their wave number. The G-band of rGO and Co-rGO nanohybrid appears at 1586 cm −1 and 1585 cm −1 respectively, whereas G-band of GO is observed at 1600 cm −1 [15,16]. Compared with GO, the G-band of rGO and Co-rGO gets shifted towards lower wavenumber, indicating the reduction of GO into rGO [15].…”
Section: Resultsmentioning
confidence: 95%
“…Here, NaAc was used as an electrostatic stabilizer which can stop particle agglomeration; EDA and EG act as the solvent media for proper dispersion of Co NPs. After proper dispersion, the mixture was transferred in a furnace under 200 °C for 12 h. In this solvothermal reaction, EDA plays a significant role in the evolution of Co-rGO nanohybrid, and EG acts as a reducing agent which contributes to the reduction of GO into rGO [ 15 , 16 ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Graphite oxide was prepared by using Staudenmaier's method with slight modification [13,15,16]. In a 500-ml beaker, 180 ml of sulfuric acid and 90 ml of nitric acid were added under an ice bath.…”
Section: Synthesis Of Graphite Oxidementioning
confidence: 99%
“…Co-rGO nanohybrid was synthesized by a simple solvothermal synthesis method as described by our group in the previous study [13,15,16]. In a typical synthesis protocol, 80 ml ethylene glycol, 15 ml ethylene-diamine, 6 g sodium acetate, 200 mg graphite oxide, and 50 mg as-synthesized cobalt nanoparticles have been sonicated in a beaker for 3 h. Further, the dispersed solution was transferred into a 100 ml autoclave and heated at temperature 200°C for 12 h. Finally, the reaction mixture was allowed to cool at ambient temperature, purified by ethanol several times, and the obtained product was dried in a vacuum furnace at 60°C.…”
Control over the magnetic interactions in magnetic nanoparticles (MNPs) is a crucial issue to the future development of nanometer-sized integrated "spintronic" applications. Here, we have developed a nanohybrid structure to achieve room temperature ferromagnetism, via a facile, effective, and reproducible solvothermal synthesis method. The plan has been put onto cobalt (Co) NPs, where the growth of Co NPs on the surface of reduced graphene oxide (rGO) nanosheets switches the magnetic interactions from superparamagnetic to ferromagnetic at room temperature. Switching-on ferromagnetism in this nanohybrid may be due to the hybridization between unsaturated 2p z orbitals of graphene and 3d orbitals of Co, which promotes ferromagnetic long-range ordering. The ferromagnetic behavior of Co-rGO nanohybrid makes it excellent material in the field of spintronics, catalysis, and magnetic resonance imaging.
“…All three materials contain four bands, namely D, G, 2D, and D + G, with a slight change in their wave number. The G-band of rGO and Co-rGO nanohybrid appears at 1586 cm −1 and 1585 cm −1 respectively, whereas G-band of GO is observed at 1600 cm −1 [15,16]. Compared with GO, the G-band of rGO and Co-rGO gets shifted towards lower wavenumber, indicating the reduction of GO into rGO [15].…”
Section: Resultsmentioning
confidence: 95%
“…Here, NaAc was used as an electrostatic stabilizer which can stop particle agglomeration; EDA and EG act as the solvent media for proper dispersion of Co NPs. After proper dispersion, the mixture was transferred in a furnace under 200 °C for 12 h. In this solvothermal reaction, EDA plays a significant role in the evolution of Co-rGO nanohybrid, and EG acts as a reducing agent which contributes to the reduction of GO into rGO [ 15 , 16 ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Graphite oxide was prepared by using Staudenmaier's method with slight modification [13,15,16]. In a 500-ml beaker, 180 ml of sulfuric acid and 90 ml of nitric acid were added under an ice bath.…”
Section: Synthesis Of Graphite Oxidementioning
confidence: 99%
“…Co-rGO nanohybrid was synthesized by a simple solvothermal synthesis method as described by our group in the previous study [13,15,16]. In a typical synthesis protocol, 80 ml ethylene glycol, 15 ml ethylene-diamine, 6 g sodium acetate, 200 mg graphite oxide, and 50 mg as-synthesized cobalt nanoparticles have been sonicated in a beaker for 3 h. Further, the dispersed solution was transferred into a 100 ml autoclave and heated at temperature 200°C for 12 h. Finally, the reaction mixture was allowed to cool at ambient temperature, purified by ethanol several times, and the obtained product was dried in a vacuum furnace at 60°C.…”
Control over the magnetic interactions in magnetic nanoparticles (MNPs) is a crucial issue to the future development of nanometer-sized integrated "spintronic" applications. Here, we have developed a nanohybrid structure to achieve room temperature ferromagnetism, via a facile, effective, and reproducible solvothermal synthesis method. The plan has been put onto cobalt (Co) NPs, where the growth of Co NPs on the surface of reduced graphene oxide (rGO) nanosheets switches the magnetic interactions from superparamagnetic to ferromagnetic at room temperature. Switching-on ferromagnetism in this nanohybrid may be due to the hybridization between unsaturated 2p z orbitals of graphene and 3d orbitals of Co, which promotes ferromagnetic long-range ordering. The ferromagnetic behavior of Co-rGO nanohybrid makes it excellent material in the field of spintronics, catalysis, and magnetic resonance imaging.
“…The input to the space charge polarization acts because of the heterogeneity of the nanocomposite material. In heterogeneous dielectric materials, there is an accumulation of virtual charges on the interfaces of two mediums with different dielectric constants and conductivities, which lead to interfacial polarization and is called Maxwell–Wagner polarization [ 68 , 69 ]. It can be observed that the values of ε′ and ε″ are increased with the increase of the size of superparamagnetic ZnFe 2 O 4 nanoparticles in prepared nanocomposites.…”
Superparamagnetic ZnFe2O4 spinel ferrite nanoparticles were prepared by the sonochemical synthesis method at different ultra-sonication times of 25 min (ZS25), 50 min (ZS50), and 100 min (ZS100). The structural properties of ZnFe2O4 spinel ferrite nanoparticles were controlled via sonochemical synthesis time. The average crystallite size increases from 3.0 nm to 4.0 nm with a rise of sonication time from 25 min to 100 min. The change of physical properties of ZnFe2O4 nanoparticles with the increase of sonication time was observed. The prepared ZnFe2O4 nanoparticles show superparamagnetic behavior. The prepared ZnFe2O4 nanoparticles (ZS25, ZS50, and ZS100) and reduced graphene oxide (RGO) were embedded in a polyurethane resin (PUR) matrix as a shield against electromagnetic pollution. The ultra-sonication method has been used for the preparation of nanocomposites. The total shielding effectiveness (SET) value for the prepared nanocomposites was studied at a thickness of 1 mm in the range of 8.2–12.4 GHz. The high attenuation constant (α) value of the prepared ZS100-RGO-PUR nanocomposite as compared with other samples recommended high absorption of electromagnetic waves. The existence of electric-magnetic nanofillers in the resin matrix delivered the inclusive acts of magnetic loss, dielectric loss, appropriate attenuation constant, and effective impedance matching. The synergistic effect of ZnFe2O4 and RGO in the PUR matrix led to high interfacial polarization and, consequently, significant absorption of the electromagnetic waves. The outcomes and methods also assure an inventive and competent approach to develop lightweight and flexible polyurethane resin matrix-based nanocomposites, consisting of superparamagnetic zinc ferrite nanoparticles and reduced graphene oxide as a shield against electromagnetic pollution.
Two‐dimensional (2D) materials possess special physical and chemical properties. They have been proved to have potential application advantage in the microwave absorption (MA) and electromagnetic interference (EMI) shielding. Particularly, they exhibit positive shielding and absorbing response to EMI. Here, the research progress of preparation, electromagnetic performance and microwave shielding/absorbing mechanisms of 2D composite materials are introduced. Effective preparation routes including introducing heteroatoms, constructing unique structures and 2D composite materials are described. Furthermore, the application prospects and challenges for the development of novel EMI materials are expatiated.
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