This study is focused
on the preparation of the CuS/RGO nanocomposite
via the hydrothermal method using GO and Cu–DTO complex as
precursors. X-ray diffraction, Fourier-transform infrared spectroscopy,
and Raman and X-ray photoelectron spectroscopy study revealed the
formation of the CuS/RGO nanocomposite with improved crystallinity,
defective nanostructure, and the presence of the residual functional
group in the RGO sheet. The morphological study displayed the transformation
of CuS from nanowire to quantum dots with the incorporation of RGO.
The galvanostatic charge/discharge curve showed that the CuS/RGO nanocomposite
(12 wt % Cu–DTO complex) has tremendous and outperforming specific
capacitance of 3058 F g–1 at 1 A g–1 current density with moderate cycling stability (∼60.3% after
1000 cycles at 10 A g–1). The as-prepared nanocomposite
revealed excellent improvement in specific capacitance, cycling stability,
Warburg impedance, and interfacial charge transfer resistance compared
to neat CuS. The fabricated nanocomposites were also investigated
for their bulk DC electrical conductivity and EMI shielding ability.
It was observed that the CuS/RGO nanocomposite (9 wt % Cu–DTO)
exhibited a total electromagnetic shielding efficiency of 64 dB at
2.3 GHz following absorption as a dominant shielding mechanism. Such
a performance is ascribed to the presence of interconnected networks
and synergistic effects.
ZrO2/MWCNT nanocomposites have been prepared by simple refluxing method and characterized by X-ray diffraction (XRD). Fourier-transform infrared spectroscopy (FTIR), and Raman analysis suggests chemical interactions present between zirconia and Multiwalled carbon nanotube
(MWCNT) in the as prepared nanocomposites. Electromagnetic inteference shielding efficiencies (EMI SE) for the nanocomposites were found to increase with increasing amount of MWCNT loading. Highest EMI SE value of 29.1–30.5 dB was obtained for nanocomposite containing 15 wt% loading
of MWCNT in the microwave frequency range of 2–8 GHz. This optimum performance is due to several factors like highest percentage of intermolecular H-bonding, highly defective, interconnected network structure, high conductivity and dielectric permittivities of the nanocomposites.
The
present work reports on the fabrication of a lightweight microwave
absorber comprising MnCo2O4 prepared from the
urea complex of manganese (Mn)/cobalt (Co) and nitrogen-doped reduced
graphite oxide (NRGO) by facile hydrothermal method followed by annealing
process and characterized. The phase analysis, compositional, morphological,
magnetic, and conductivity measurements indicated dispersion of paramagnetic
MnCo2O4 spherical particles on the surface of
NRGO. Our findings also showed that Mn, Co–urea complex, and
GO in the weight ratio of 1:4 (NGMC3) exhibited maximum shielding
efficiency in the range of 55–38 dB with absorption as an overall
dominant shielding mechanism. The reflection loss of NGMC3 was found
to be in the range of −90 to −77 dB with minima at −103
dB (at 2.9 GHz). Such outstanding electromagnetic wave absorption
performance of NRGO/MnCo2O4 nanocomposite compared
to several other metal cobaltates could be attributed to the formation
of percolated network assisted electronic polarization, interfacial
polarization and associated relaxation losses, conductance loss, dipole
polarization and corresponding relaxation loss, impedance matching,
and magnetic resonance to some extent.
The present work is focused on the synthesis of bismuth sulfide (Bi2S3) nanorods/Reduced graphene oxide (RGO) composites via a one-step hydrothermal method using GO and bismuth nitrate in 5:1, 3:1...
Anharmonicity and impurities have a significant impact on the dynamic and optical properties of crystalline solids. In this report, we have performed temperature-dependent Raman spectroscopy in the range of 300–800 K for hydrothermally synthesized titanium dioxide (TiO2) nanorod composed microflowers doped with Cu. X-ray diffraction and high resolution transmission electron microscopy confirm the pure rutile phase of both pristine and Cu doped TiO2. The most intense Eg and A1g modes exhibit a frequency redshift, and the linewidth increases with temperature, which leads to Fano line shape type asymmetry. The anharmonicity induced phonon frequency shift as a function of temperature was well fitted using the Klemens model by combining three and four-phonon coupling processes. The Raman modes soften with the increasing concentration of Cu doping. The Cu dopant acts as an impurity, which manifests defect states to tune the bandgap and shorten the phonon lifetime and anharmonicity. Such an anharmonic effect can lead to applications in the sensing devices with suitable thermal and electrical conductivities.
Manipulating light at the sub-wavelength level is a crucial feature of surface plasmon resonance (SPR) properties for a wide range of nanostructures. Noble metals like Au and Ag are most commonly used as SPR materials. Significant attention is being devoted to identify and develop non-noble metal plasmonic materials, whose optical properties can be reconfigured for plasmonic response by structural phase changes. Chromium(Cr) which supports plasmon resonance, is a transition metal with shiny finished, highly non-corrosive, and bio-compatible alloys, making it an alternative plasmonic material. We have synthesized Cr micro-rods from a bi-layer of Cr/Au thin films, which evolves from Face Centered Cubic (FCC) to Hexagonal Close Packed (HCP) phase by thermal activation in a forming gas ambient. We employed optical absorption spectroscopy and cathodoluminescence (CL) imaging spectroscopy to observe the plasmonic modes from the Cr micro-rod. The origin of three emission bands that spread over UV-Vis-IR wavelength is established theoretically by considering the critical points of the second-order derivative of the macroscopic dielectric function obtained from density functional theory (DFT) matches with interband/intraband transition of electrons observed in density of states vs. energy graph. The experimentally observed CL emission peaks closely match the s-d and d-d band transition obtained from DFT calculations. Our findings on plasmonic modes in Cr(HCP) phase can expand the range of plasmonic material beyond noble metal with tunable plasmonic emissions for plasmonic-based optical technology.
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