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The significance of graphene and its two-dimensional (2D) analogous inorganic layered materials especially as hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS 2 ) for “clean energy” applications became apparent over the last few years due to their extraordinary properties. In this review article we study the current progress and selected challenges in the syntheses of graphene, h-BN and MoS 2 including energy storage applications as supercapacitors and batteries. Various substrates/catalysts (metals/insulator/semiconducting) have been used to obtain graphene, h-BN and MoS 2 using different kinds of precursors. The most widespread methods for synthesis of graphene, h-BN and MoS 2 layers are chemical vapor deposition (CVD), plasma-enhanced CVD, hydro/solvothermal methods, liquid phase exfoliation, physical methods etc. Current research has shown that graphene, h-BN and MoS 2 layered materials modified with metal oxide can have an insightful influence on the performance of energy storage devices as supercapacitors and batteries. This review article also contains the discussion on the opportunities and perspectives of these materials (graphene, h-BN and MoS 2 ) in the energy storage fields. We expect that this written review article including recent research on energy storage will help in generating new insights for further development and practical applications of graphene, h-BN and MoS 2 layers based materials.

Nanofluids have become of interest in recent years thanks to their improved thermal properties, which make them especially interesting for microchannel heat sink applications. In this study, we prepared two aqueous nanofluids based on reduced graphene oxide (rGO) decorated with manganese dioxide (MnO2) at a concentration of 0.1 wt.%. The difference between the two nanofluids was in the preparation of the reduced graphene oxide decorated with MnO2. In the first case, the manganese salt was mixed with ascorbic acid before GO reduction with NaOH, and in the second case, the GO reduction with NaOH occurred under ascorbic acid. Ascorbic acid not only plays the role of a non-toxic and ecofriendly reducing agent but also acts as an important parameter to control the reaction kinetics. The structural, microstructural and spectral characterizations of the MnO2/rGO nanocomposite were conducted via X-ray diffractometry (XRD), Raman spectroscopy, FT-IR, TEM, SEM and EDS analyses. Moreover, the synthesized MnO2/rGO nanocomposites were utilized as nanofluids and their stability, thermal conductivity and rheological behaviors were studied. The thermal conductivity of the MnO2/rGO and MnO2AsA/rGO nanofluids was 17% and 14.8% higher than that of water for the average temperature range, respectively, but their viscosity remained statistically equal to that of water. Moreover, both nanofluids presented Newtonian behavior in the analyzed shear rate range. Therefore, both MnO2/rGO and MnO2AsA/rGO nanofluids are promising alternatives for use in applications with micro- and millichannel heat sinks.

Metal–organic frameworks (MOFs) are hybrid materials that are being explored as active electrode materials in energy storage devices, such as rechargeable batteries and supercapacitors (SCs), due to their high surface area, controllable chemical composition, and periodic ordering. However, the facile and controlled synthesis of a pure MOF phase without impurities or without going through a complicated purification process (that also reduces the yield) are challenges that must be resolved for their potential industrial applications. Moreover, various oxide formations of the Ni during Ni-MOF synthesis also represent an issue that affects the purity and performance. To resolve these issues, we report the controlled synthesis of nickel-based metal–organic frameworks (NiMOFs) by optimizing different growth parameters during hydrothermal synthesis and by utilizing nickel chloride as metal salt and H2bdt as the organic ligand, in a ratio of 1:1 at 150 °C. Furthermore, the synthesis was optimized by introducing a magnetic stirring stage, and the reaction temperature varied across 100, 150, and 200 °C to achieve the optimized growth of the NiMOFs crystal. The rarely used H2bdt ligand for Ni-MOF synthesis and the introduction of the ultrasonication stage before putting it in the furnace led to the formation of a pure phase without impurities and oxide formation. The synthesized materials were further characterized by powder X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), and UV–vis spectroscopy. The SEM images exhibited the formation of nano NiMOFs having a rectangular prism shape. The average size was 126.25 nm, 176.0 nm, and 268.4 nm for the samples (1:1)s synthesized at 100 °C, 150 °C, and 200 °C, respectively. The electrochemical performances were examined in a three-electrode configuration, in a wide potential window from −0.4 V to 0.55 V, and an electrolyte concentration of 2M KOH was maintained for each measurement. The charge–discharge galvanostatic measurement results in specific capacitances of 606.62 F/g, 307.33 F/g, and 287.42 F/g at a current density of 1 A/g for the synthesized materials at 100 °C, 150 °C, and 200 °C, respectively.

We report the observations made on the synthesis and characterization of C–N nanotube blocks and Y-junctions in bamboo-like C–N nanotubes. The C–N nanotube Blocks have been synthesized by pyrolyzing the mixture of silver nitrate acetonitrile solution and ferrocene benzene solution. The structural/microstructural characterization of the as-synthesized material has been done using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopic (XPS) analysis has been carried out to confirm the presence of nitrogen in nanotubes. These investigations reveal the formation of blocks of bamboo-like nanotubes having the dimension 300 × 200 × 30 μm and the diameter is 20–50 nm. We also observe the formation of Y-junctions in bamboo-like nanotubes as we spray the acetonitrile ferrocene and AgNO 3 mixture. The length of the synthesized Y-junction nanotube bundles is ~2 μm. Some more complex Ψ-shaped junctions are also found to be present. The diameters of the Y-junction nanotubes is ~80 nm at the junction and 25–50 nm at the branches.

Determining the electron field emission (FE) turn-on field of the silicon nanowires(SiNWs) array can better adapt to the application of field-assisted photocathode. Here, we report the observations of FE from SiNWs grown on n-type Si(100) by utilizing silver induce chemical etching (SICE) approach. The growth of SiNWs is confirmed by XPS and XRD spectra and the optical band gaps, studied from the Kubelka-Munk function reveals the red shifting behavior. The grown SiNWs show an excellent FE property. The new proposed analytical framework enables one to understand the FE properties in better sense as compared to the conventional utilized framework, named as Fowler-Nordhiem (F-N) approach. It improves the analysis by introducing a new parameter i.e. boost-factor to take care of the FE data in totality unlike the traditional framework, where only currents were considered for higher electric fields. Moreover, it also addresses the ambiguity present in the previously used approach. A quantum mechanical model is adopted to explain the improved FE properties from these NWs by using the concept of tunneling probability. These results can enrich our knowledge on the FE of SiNWs and are highly related to the development of the next-generation of Si nano-electronic devices.

In the present work, halloysite nanotubes modified with gold nanoparticles (AuNPs-HNT) are successfully prepared by wet chemical method for the catalytic degradation of phenothiazine dyes (azure B (AZB) and toluidine blue O (TBO)) and also cleaner reduction of 4-(4-nitrophenyl)morpholine (4NM) in the sodium borohydride (NaBH 4 ) media. The catalyst is formulated by modifying the HNT support with a 0.964% metal loading using the HNT supports modified with 3-aminopropyl-trimethoxysilane (APTMS) coupling agent to facilitate the anchoring sites to trap the AuNPs and to prevent their agglomeration/aggregation. The AuNPs-HNT catalyst is investigated for structural and morphological characterization to get insights about the formation of the catalyst for the effective catalytic reduction of dyes and 4NM. The microscopic studies demonstrate that AuNPs (2.75 nm) are decorated on the outer surface of HNT. The as-prepared AuNPs-HNT catalyst demonstrates AZB and TBO dye degradation efficiency up to 96% in 10 and 11 min, respectively, and catalytic reduction of 4NM to 4-morpholinoaniline (MAN) is achieved up to 97% in 11 min, in the presence of NaBH 4 without the formation of any by-products. The pseudo-first-order rate constant ( K 1 ) value of the AuNPs-HNT catalyst for AZB, TBO, and 4NM were calculated to be 0.0078, 0.0055, and 0.0066 s −1 , respectively. Moreover, the synthesized catalyst shows an excellent reusability with stable catalytic reduction for 7 successive cycles for both the dyes and 4NM. A plausible mechanism for the catalytic dye degradation and reduction of 4NM by AuNPs-HNT catalyst is proposed as well. The obtained results clearly indicate the potential of AuNPs-HNT as an efficient catalyst for the removal of dye contaminants from the aquatic environments and cleaner reduction of 4NM to MAN, insinuating future pharmaceutical applications.

Nanofluids have become of interest in recent years thanks to their improved thermal properties, which make them especially interesting for microchannel heat sink applications. In this study, we prepared two aqueous nanofluids based on reduced graphene oxide (rGO) decorated with manganese dioxide (MnO[sub.2] ) at a concentration of 0.1 wt.%. The difference between the two nanofluids was in the preparation of the reduced graphene oxide decorated with MnO[sub.2] . In the first case, the manganese salt was mixed with ascorbic acid before GO reduction with NaOH, and in the second case, the GO reduction with NaOH occurred under ascorbic acid. Ascorbic acid not only plays the role of a non-toxic and ecofriendly reducing agent but also acts as an important parameter to control the reaction kinetics. The structural, microstructural and spectral characterizations of the MnO[sub.2] /rGO nanocomposite were conducted via X-ray diffractometry (XRD), Raman spectroscopy, FT-IR, TEM, SEM and EDS analyses. Moreover, the synthesized MnO[sub.2] /rGO nanocomposites were utilized as nanofluids and their stability, thermal conductivity and rheological behaviors were studied. The thermal conductivity of the MnO[sub.2] /rGO and MnO[sub.2] AsA/rGO nanofluids was 17% and 14.8% higher than that of water for the average temperature range, respectively, but their viscosity remained statistically equal to that of water. Moreover, both nanofluids presented Newtonian behavior in the analyzed shear rate range. Therefore, both MnO[sub.2] /rGO and MnO[sub.2] AsA/rGO nanofluids are promising alternatives for use in applications with micro- and millichannel heat sinks.

Three kinds of carbon nanostructures, i.e., graphene nanoflakes (GNFs), multi walled carbon nanotubes (MWCNTs), and spherical carbon nanoparticles (SCNPs) were comparatively investigated in one run experiment. These carbon nanostructures are located at specific location inside the direct current plasma-assisted arc discharge chamber. These carbon nanomaterials have been successfully synthesized using graphite as arcing electrodes at 400 torr in helium (He) atmosphere. The SCNPs were found in the deposits formed on the cathode holder, in which highly curled graphitic structure are found in majority. The diameter varies from 20 to 60 nm and it also appears that these particles are self-assembled to each other. The MWCNTs with the diameter of 10–30 nm were obtained which were present inside the swelling portion of cathode deposited. These MWCNTs have 14–18 graphitic layers with 3.59 Å interlayer spacing. The GNFs have average lateral sizes of 1–5 μm and few of them are stacked layers and shows crumpled like structure. The GNFs are more stable at low temperature (low mass loss) but SCNPs have low mass loss at high temperature.

हिन्दी साहित्य में प्रेमाख्यानक परम्परा के आरम्भ से ही जन साधारण के लोकगीतों और लोक वार्ताओं के रूप में शुद्ध प्रेमाख्यानों का निर्माण होता रहा है। जिसमें हिन्दुओं और मुसलमानों का समान रूप से योगदान रहा है। हिन्दी साहित्य के कुछ विद्वान इतिहासकारों ने प्रमाख्यानों की परम्परा को सूफी मुसलमानों तक ही संबन्धित माना परन्तु यह तथ्य भ्रान्तिकारी रहा क्योंकि सूफी असूफी का वर्गीकरण कदापि वैज्ञानिक प्रतीत नहीं होता । यह तथ्य साम्प्रदायिकता की संकीर्ण भावना को जन्म देती है जो भारतीय संस्कृति के सन्दर्भ में प्रेमाख्यानों के विशाल महत्व में कहीं दिखाई नहीं पड़ता । उपरोक्त संकीर्णता से मुक्त होकर ही मध्यकालीन हिन्दी प्रेमाख्यानों के कथानकों का सफल शास्त्रीय अध्ययन संभव है और इसी के माध्यम से प्रेमाख्यानों की आत्मा की सहजता प्रकट की जा सकती है। हिन्दी साहित्य में एकाध को छोड़कर समस्त प्रेमाख्यान लौकिक प्रेम को लेकर ही चलते है जिनके मुख्य आधार लोक मानस