Graphene oxide (GO) was non-covalently functionalized using sulfanilic acid azocromotrop (SAC) followed by hydrazine reduction to achieve SAC functionalized reduced GO (SAC-rGO). Fourier transform ...infrared spectra analysis and electrical conductivity measurements confirmed the successful functionlization and reduction of GO. The electrical conductivity of ~515 S•m−1 for SAC-rGO was recorded. The non-covalently functionalized reduced GO was subsequently dispersed in epoxy matrix at the loading level of 0.3 to 0.5 wt% to investigate its electromagnetic interference (EMI) shielding properties. The morphological and structural characterization of the SAC-rGO/epoxy composites was carried out using X-ray diffraction and Transmission electron microscopy analysis, which revealed the good dispersion of SAC-rGO in the epoxy. The SAC-rGO/epoxy composites showed the EMI shielding of −22.6 dB at the loading of 0.5 wt% SAC-rGO. Dynamical mechanical properties of the composites were studied to establish the reinforcing competency of the SAC-rGO. The storage modulus of the composites was found to increase within the studied temperature. Thermal stability of pure epoxy and its composites were compared by selecting the temperatures at 10 and 50% weight loss, respectively.
The present work describes the dual role of graphene as an initiator and filler for polymerization of N-vinylcarbazole and formation of poly(N-vinylcarbazole)/graphene (PVK/Gr) nanocomposites. ...Fourier transformation infrared (FTIR) and X-ray diffraction (XRD) studies confirmed the formation of PVK as well its graphene nanocomposites. Scanning electron micrograph (SEM) and transmission electron microscopy (TEM) revealed the graphene platelets are dispersed in the matrix of spherical PVK. X-ray photoelectron spectroscopy (XPS) also revealed formation of PVK and presence of interaction between PVK and graphene. Thermograivmetric analysis (TGA) have shown that the thermal stability of PVK/graphene (0.5 wt%) is maximum improved by -76 degrees C compared to neat PVK, when 20 wt% weight loss is taken as a point of comparison. Ultraviolet (UV) and photoluminescence (PL) studies established the charge transfer from polymer chains to the graphene platelets. Dielectric measurements have shown the maximum improvement (87%) in dielectric constant (ε) with 1 wt% graphene loading. The variation of ac conductivity (σ) with frequency (ψ) confirmed the insulating behavior of PVK/graphene nanocomposites possessing high dielectric constant.
Nanorods of Sb2S3 have been synthesized by a surfactant assisted hydrothermal method. The formation of nanorods through flowerlike morphology with an intermediate straw tide like structure has been ...depicted by scanning electron microscopy (SEM) study. This type of observation is the first of its kind for this material, and it has been explained on the basis of a two step heterogeneous nucleation−growth mechanism followed by crystal splitting. Raman spectroscopy of the nanorods has been carried out to provide an idea about their purity. An increase in the band gap is observed for Sb2S3 with nanorod-type morphology. Photoluminescence (PL) shows no sign of quantum confinement effect, though a large increase in intensity for nanorods has been observed compared to the flowerlike morphology.
The present work reports on the fabrication of a lightweight microwave absorber comprising MnCo
O
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 MnCo
O
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/MnCo
O
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.
Dyes are considered as recalcitrant compounds and are not easily removed through conventional water treatment processes. The present study demonstrated the fabrication of polyaniline hollow ...microsphere (PNHM)/MnO2/Fe3O4 composites by in situ deposition of MnO2 and Fe3O4 nanoparticles on the surface of PNHM. The physicochemical characteristics and adsorption behavior of the prepared PNHM/MnO2/Fe3O4 composites towards the removal of toxic methyl green (MG) and Congo red (CR) dyes have been investigated. The characterization study revealed the successful synthesis of the prepared PNHM/MnO2/Fe3O4 adsorbent with a high Brunauer–Emmett–Teller (BET) surface area of 191.79 m2/g. The batch adsorption study showed about 88 and 98% adsorption efficiencies for MG and CR dyes, respectively, at an optimum dose of 1 g/L of PNHM/MnO2/Fe3O4 at pH ∼6.75 at room temperature (303 ± 3 K). The adsorption phenomena of MG and CR dyes were well described by the Elovich and pseudo-second-order kinetics, respectively, and Freundlich isotherm model. The thermodynamics study shows that the adsorption reactions were endothermic and spontaneous in nature. The maximum adsorption capacity (Q max) for MG and CR dyes was observed as 1142.13 and 599.49 mg/g, respectively. The responsible adsorption mechanisms involved in dye removal were electrostatic interaction, ion exchange, and the formation of the covalent bonds. The coexisting ion study revealed that the presence of phosphate co-ion considerably reduced the CR dye removal efficiency. However, the desorption–regeneration study demonstrated the successful reuse of the spent PNHM/MnO2/Fe3O4 material for the adsorption of MG and CR dyes for several cycles. Given the aforementioned findings, the PNHM/MnO2/Fe3O4 nanocomposites could be considered as a promising adsorbent for the remediation of dye-contaminated water.
The present work is focused on room-temperature reduction by subjecting reduction of an aqueous KMnO4 and KMnO4/graphene oxide (GO) dispersion by Fehling solution B in one step to form δ-MnO2, ...exhibiting hierarchical nanoflowers and their nanocomposites (δ-MnO2/reduced graphene oxide). This was followed by their characterization by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), surface area measurements, and DC conductivity. The effect of the concentration of a reducing agent on the morphological evolution of δ-MnO2 has also been proposed. Further, these materials were also investigated for their performance in electromagnetic interference (EMI) shielding efficiency (SE) in the frequency range of 2–8 GHz. These findings showed the highest total shielding efficiency (∼39 dB) of the δ-MnO2/reduced graphene oxide (RGO)-1.0 nanocomposite consisting of 5.5 wt % RGO following reflection as a dominant mechanism. Such excellent performance was attributed to the poor impedance matching between MnO2/RGO, the formation of an interconnected conducting network, and interfacial polarization. It is anticipated that δ-MnO2/RGO nanocomposites synthesized by a simple room-temperature reaction in one step could be promising candidates as lightweight and high-performance EMI shielding materials for multifaceted applications.
The pharmaceuticals industry has played an important role in developing medicines for improving health and quality of life in treating humans and animals around the world. But it is also considered ...to be one of the sources of pollutants entering deliberately or accidentally into global water bodies causing toxicity that eventually threatens human health, aquatic organisms and environments even at low concentrations. These contaminants are non-biodegradable and cannot be completely removed from various water matrices following conventional treatment methods. In this regard, photodegradation techniques involving modified/unmodified semiconducting materials have attracted a lot of attention as a promising solution in achieving complete antibiotic degradation with the generation of non-toxic by-products. In view of this, the present review article summarizes current research progress in the removal of several emerging contaminants, such as acetaminophen, amoxicillin, sulfamethoxazole, norfloxacin, ibuprofen, ciprofloxacin, tetracycline, diclofenac and atenolol in water. Considerable emphasis has been placed on metal oxides and carbon-based photocatalysts following their modification through doping with metals and non-metals, metal loading, the formation of composites, immobilization and heterostructure/heterojunction approaches. Finally, the review ends with future prospects for nanomaterial-based heterogeneous photocatalysts in the removal of pharmaceutical contaminants from water.
The pharmaceuticals industry has played an important role in developing medicines for improving health and quality of life in treating humans and animals around the world.
The present work is focused on the synthesis of bismuth sulfide (Bi 2 S 3 ) nanorod/reduced graphene oxide (RGO) composites via a one-step hydrothermal method using GO and bismuth nitrate in 5 : 1, 3 ...: 1 and 2 : 1 weight ratios and their characterization. The morphological studies revealed the formation of homogeneously dispersed Bi 2 S 3 nanorods on RGO sheets along with occasional wrapping in the Bi 2 S 3 nanorod/RGO (3 : 1) composite. XRD, FTIR, Raman and XPS studies suggested the incorporation of Bi 2 S 3 in RGO sheets. The galvanostatic charge–discharge measurements showed that the Bi 2 S 3 nanorod/RGO (3 : 1) composite exhibited the highest specific capacitance (1932 F g −1 ) at 1 A g −1 in the presence of 2 M aqueous KOH in a three-electrode cell. This is ascribed to the enhanced contact area between metal sulfide nanoparticles and RGO, increased conductivity and synergistic effect of Bi 2 S 3 and RGO. The optimized Bi 2 S 3 nanorod/RGO (3 : 1) composite also maintained an excellent cycling stability with ∼100% capacitance retention after 700 cycles. It is noted that the supercapacitor performance of the Bi 2 S 3 nanorod/RGO (3 : 1) composite was better than group V and VI metal chalcogenides and their nanocomposites reported in several previous studies.
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