Herein, we report the gadolinium-doped MoS2-reduced graphene oxide (Gd@MoS2-rGO) nanocomposite by using a facile two-step hydrothermal method for high-performance electromagnetic interference (EMI) ...shielding applications. Structural and microstructural properties of MoS2-rGO and Gd@MoS2-rGO nanocomposite were investigated by scanning electron microscope, transmission electron microscope, X-ray diffraction, and Raman spectroscopy. Gd-doping content in MoS2-rGO nanocomposite has successively increased the electrical conductivity to improve imaginary permittivity (ε″) and dielectric loss tangent (tanδε) in the frequency range of 8.0–12.0 GHz. Pure MoS2-rGO nanocomposite exhibits low total shielding effectiveness (SET ∼ 16.18 dB) in entire frequency range as compared to 10% Gd@ MoS2-rGO (SET ∼ 19.25 dB) and 20% Gd@ MoS2-rGO (SET ∼ 20.47 dB) nanocomposite. In this work, Gd act as a highly conductive network between MoS2 and rGO nanosheet coupled with a large surface area, which leads to the migration of fast charge carriers at multi-interfaces. The results suggest that the Gd@MoS2-rGO nanocomposite have great potential applications as a candidate for a new type of microwave absorption and EMI shielding material.
•First-time report Gd@MoS2-rGO nanocomposite by two-step hydrothermal method.•Higher conductivity and dielectric loss for 20% Gd@MoS2-rGO nanocomposite.•Most of the EM energy attenuated by 20% Gd@MoS2-rGO nanocomposite.
Herein, we reported the electromagnetic interference performance of NiFe2O4/rGO nanocomposite. In this study NiFe2O4 nanoparticles was synthesized by co-precipitation route and the magnetic ...nanoparticles were incorporated on reduced graphene oxide (rGO) using a solvothermal method. The detailed properties of synthesized materials were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), tunneling electron microscopy (TEM), Raman spectroscopy, vibrating sample magnetometer (VSM) system, and vector network analyzer (VNA). The electromagnetic interference (EMI) shielding property of composite materials was investigated in the 8.2–12.4 GHz (X-band) frequency region. The results depicted the significant dielectric and magnetic loss in the nanocomposite as compared to rGO. Consequently, composite has improved impedance matching characteristics, which required for high electromagnetic wave absorption. Moreover, the study showed that shielding effectiveness further improves with increasing nanoparticles concentration in nanocomposite, which is due to increased interconnected network between NiFe2O4 and rGO. Furthermore, total shielding effectiveness (SET) of (35/65) NiFe2O4/rGO nanocomposite of thickness 2 mm is 38.2 dB at 10.8 GHz, which is higher than the accompanying investigated sample. It could be inferred that the redeeming properties of high dielectric and magnetic loss, enhanced absorption and multiple reflections of (35/65) NiFe2O4/rGO nanocomposite resulted in high shielding effectiveness. Therefore, this result mean that NiFe2O4/rGO nanocomposite is a promising shielding material for application in microwave absorption appliances.
The self-assembled three dimensional (3D) hybrids nanostructure containing uniform growth of vertical carbon nanotubes (VCNTs) with faceted iron oxide nanoparticles (f-Fe3O4 NPs) on the surfaces of ...reduced graphene oxide nanosheets (rGO NSs) is achieved using microwave assisted approach. The formation of hierarchical 3D f-Fe3O4-VCNTs@rGO hybrids, using microwave method is a rapid, simple, and inexpensive synthetic route. First, the VCNTs grow with help of Fe NPs, and after oxidizing of Fe NPs in form of f-Fe3O4 NPs, the growth has terminated resulting in formation of small size (<500 nm) VCNTs containing f-Fe3O4 NPs on its tip. The defect- and oxygen-rich sites of rGO NSs favor the heterogeneous nucleation and growth of f-Fe3O4 NPs on the tip of VCNTs. The synthesized 3D f-Fe3O4-VCNTs@rGO hybrid shows the improved electromagnetic interference (EMI) for microwave shielding effectiveness (SE) as compared to both rGO NSs and Fe3O4 NPs@rGO NSs materials. This 3D f-Fe3O4-VCNTs@rGO hybrid demonstrates the shielding effectiveness value more than ∼25 dB as compared to Fe3O4 NPs@rGO NSs for 1.0 mm thin film of 3D f-Fe3O4-VCNTs@rGO hybrids in microwave X-band (8.2–12.4 GHz). This applied microwave synthesis approach for 3D f-Fe3O4-VCNTs@rGO hybrids is simple, fast, reproducible and scalable for advanced EMI shielding materials. It can be concluded that the faceted Fe3O4 NPs on the tip of VCNTs which are grown in-situ on rGO NSs shows synergetic performance for EMI shielding elements in advanced application areas like spacecraft and aircraft.
In this article, we proposed a facile one-step synthesis of Fe
3
O
4
nanoparticles of different shapes and sizes by co-precipitation of FeCl
2
with piperidine. A careful investigation of TEM ...micrographs shows that the shape and size of nanoparticles can be tuned by varying the molarity of piperidine. XRD patterns match the standard phase of the spinal structure of Fe
3
O
4
which confirms the formation of Fe
3
O
4
nanoparticles. Transmission electron microscopy reveals that molar concentration of FeCl
2
solution plays a significant role in determining the shape and size of Fe
3
O
4
nanoparticles. Changes in the shape and sizes of Fe
3
O
4
nanoparticles which are influenced by the molar concentration of FeCl
2
can easily be explained with the help of surface free energy minimization principle. Further, to study the magnetic behavior of synthesized Fe
3
O
4
nanoparticles, magnetization vs. magnetic field (M-H) and magnetization vs. temperature (M-T) measurements were carried out by using Physical Property Measurement System (PPMS). These results show systematic changes in various magnetic parameters like remanent magnetization (Mr), saturation magnetization (Ms), coercivity (Hc), and blocking temperature (
T
B
) with shapes and sizes of Fe
3
O
4
. These variations of magnetic properties of different shaped Fe
3
O
4
nanoparticles can be explained with surface effect and finite size effect.
In this paper, authors report a facile synthesis of reduced graphene oxide-ZnO (rGO-ZnO) nanocomposite via the solvothermal method for excellent electromagnetic interference (EMI) shielding ...application. Various characterization tools such as Transmission Electron Microscope (TEM), X-ray diffractometer (XRD) and Raman spectroscope have been employed to understand the morphology and crystal structure of rGO-ZnO nanocomposite, which clearly reveals ZnO nanoparticles (with average size ∼25 nm) to get dispersed well over the surface of rGO. These ZnO nanoparticles, assembled over the top of rGO sheets, form an rGO-ZnO heterostructure with enhanced polarization centers. ZnO nanostructures not only prevent rGO nanosheets to agglomerate but also to contribute significantly in improved scattering, dielectric loss, and impedance matching properties of heterostructure nanocomposite. EMI shielding properties of rGO-ZnO nanocomposites have been evaluated in X-band frequency range (8–12 GHz) and indicate clearly that rGO-ZnO (SET ∼ 38 dB) nanocomposite exhibits an excellent shielding property as compared to its constituent components (SET ∼ 22 dB for rGO and ∼4 dB for ZnO nanoparticles, respectively). Variation of real and imaginary parts of permittivity and permeability provides the idea of attenuating rGO-ZnO nanocomposite. Moreover, it's dielectric and magnetic loss parameters demonstrate the impedance matching characteristics of the rGO-ZnO nanocomposite.
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The effect of In incorporation is studied on the, micro-hardness compactness and elastic properties of glassy Se–Te–Cd alloys. The micro-hardness of glassy Se
75
Te
15 –
x
Cd
10
In
x
(
x
= 0, 5, 10 ...and 15) alloys is calculated at room temperature. The compactness structure of Se
75
Te
15 –
x
Cd
10
In
x
alloys is also determined from the measured densities. The micro hardness is maximum for glassy Se
75
Te
5
Cd
10
In
10
alloy and compactness minimum for same concentration. The volume of the micro-voids, their formation energy and the module of elasticity are determined using the free-volume theory and are considered in terms of average coordination number ❬
Z
❭.The module of elasticity E is increases in starting with average coordination number reach maximum then decreases and the micro-void volume
V
h
is minimum for glassy Se
75
Te
5
Cd
10
In
10
alloy.
In this study, a three-dimensional (3D) micro-flower like morphology aluminum-doped molybdenum disulfide/reduced graphene oxide (Al@MoS2/rGO) nanohybrids have been developed using a simple and ...sensitive hydrothermal approach. Their electromagnetic (EM) parameters (permittivity, permeability) and microwave shielding parameters (S11, S12) have been analyzed and reported for the first time in the microwave frequency range of 8.0–12.0 GHz. It is interesting to note that the electrical conductivity of the nanohybrids increases with the doping concentration of Al-ions, whereas skin-depth has a reverse trend. The 12% Al@MoS2/rGO nanohybrid shows a higher total electromagnetic interference shielding effectiveness (EMI SE) value about SET ~33.38 dB, whereas undoped MoS2/rGO nanohybrid exhibits a lower value around ~17.07 dB at the same thin thickness. The higher doping concentration of Al-ion creates lattice distortion and crystal defects with high charge carrier mobility between multiple interfaces and at defective sites. Hence, the Al-doping into MoS2 lattice supported on the rGO surface can greatly enhance EM wave absorption and EMI SE value. The present work suggests that the 12% Al@MoS2/rGO nanohybrid can be treated as a good microwave absorbing and shielding material and useful in various techno-commercial devices.
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•Al-doped MoS2/rGO nanohybrids were synthesized by a simple and sensitive hydrothermal approach.•First-time report Al-doped MoS2/rGO nanohybrids for electromagnetic wave shielding material.•Most of the incoming EM energy attenuated and dissipated inside the 12% Al-doped MoS2/rGO nanohybrid.•Al-ions created more lattice distortion and charge carrier mobility at multi-interfaces or defective sites.•Higher AC electrical conductivity and EMI SE values were achieved by 12% Al-doped MoS2/rGO nanohybrid.
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.
Highly luminescent ternary Zn–Ga–S quantum dots (QDs) were synthesized via a noninjection method by varying Zn/Ga ratios. X-ray diffraction and Raman investigations demonstrate composition-dependent ...changes with multiple phases including ZnGa2S4, ZnS, and Ga2S3 in all samples. Two distinct excitation pathways were identified from absorption and photoluminescence excitation spectra; among them, one is due to the band-gap transition appearing at around 375 and 395 nm, whereas another one observed nearby 505 nm originates from sub-band-gap defect states. Photoluminescence (PL) spectra of these QDs depict multiple emission noticeable at around 410, 435, 461, and 477 nm arising from crystallographic point defects formed within the band gap. The origin of these defects including zinc interstitials (IZn), zinc vacancies (VZn), sulfur interstitials (IS), sulfur vacancies (VS), and gallium vacancies (VGa) has been discussed in detail by proposing an energy-level diagram. Further, the time-dependent PL decay curve strongly suggests that the tail emission (appear around 477 nm) in these ternary QDs arises due to donor–acceptor pair recombination. This study enables us to understand the PL mechanism in new series of Zn–Ga–S ternary QDs and can be useful for the future utilization of these QDs in photovoltaic and display devices.
Uric acid (UA) level quantification is crucial for the diagnosis and treatment of cardiovascular, arthritis, renal disorder, and preeclampsia diseases. We report the solvent-assisted synthesis of ...zinc oxide (ZnO) nanoparticles (NPs) which we used to make a seed layer on a conductive fluorine-doped tin oxide (FTO) electrode. Vertically-arranged ZnO nanorods (NRs) were grown using a hydrothermal method. The ZnO NPs and NRs were characterized in detail, which revealed the smaller sizes (10-15 nm) of the NPs and the vertically-arranged nature of the NRs. Furthermore, a highly sensitive UA biosensor was constructed with vertically-arranged ZnO NRs. The electrochemical characterization of the UA biosensor (Nafion/uricase/ZnO NRs-ZnO NPs/FTO) using differential pulse voltammetry (DPV) demonstrated linearity over a wide UA concentration range (0.01-1.5 mM) with a high sensitivity (345.44 μA mM
−1
cm
−2
) and limit of detection (LOD; 2.5 μM). The biosensor also showed good selectivity, high reproducibility, and enhanced shelf-life. Additionally, practical feasibility was tested in a real (
i.e.
, human blood serum) sample. The boosted UA biosensor performance is attributed to the vertically-arranged ZnO NRs, which immobilize a large amount of enzyme owing to their high surface-to-volume ratio, compared to flat surface-based biosensors. The present strategy, using vertically-arranged ZnO NRs on NP-seeded electrodes, can be extended to fabricate different ZnO NR-based chemical/biosensing devices.
Vertically-arranged ZnO nanorods grown on a ZnO nanoparticle-seeded FTO electrode using a hydrothermal method for highly sensitive uric acid biosensor fabrication.
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