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Hiremath, Vishwanath,Cho, Min,Seo, Jeong Gil The Royal Society of Chemistry 2018 NEW JOURNAL OF CHEMISTRY Vol.42 No.24
<P>A well defined carbon nanotube threaded trimanganese tetroxide (Mn3O4@CNT) nanocomposite has been fabricated through a facile hydrothermal route using acetylacetone as a chelating agent. The Mn3O4 nano-clusters are formed by the self-assembly of numerous Mn3O4 nanostructures and the CNTs are uniformly decorated on the body of Mn3O4 nano-clusters to improve the conductivity of the composite. The porous and well-designed architecture of the Mn3O4@CNT composite could be expected to offer more electroactive sites for pseudocapacitive reactions and shorten the transportation path for the electrolyte ions. Due to these properties as well as the synergistic effect of CNTs and Mn3O4 nano-clusters, the as-synthesized Mn3O4@CNT composite, which was primarily used as a pseudocapacitive material, showed a higher specific capacitance of 81.9 F g<SUP>−1</SUP> at a current density of 0.6 A g<SUP>−1</SUP> with good cycling stability. The delivered capacitance of the composite is comparatively higher than that of the pristine Mn3O4 (53.5 F g<SUP>−1</SUP>). The facile preparation approach to balance the higher electrochemical properties of the transition metal oxides with highly conductive carbon nanotubes provides the potential for the development of novel nanocomposites for energy storage devices.</P>
Hiremath, Vishwanath,Trivino, Monica L.T.,Shavi, Raghavendra,Gebresillase, Mahlet N.,Seo, Jeong Gil North-Holland 2018 Materials letters Vol.211 No.-
<P><B>Abstract</B></P> <P>MgO-Al<SUB>2</SUB>O<SUB>3</SUB>@C spheres were synthesized via a simple sacrificial templating method using resorcinol and formaldehyde. The SEM studies revealed the presence of interconnected nanosized particles within the nanoscale region. The improved CO<SUB>2</SUB> sorption performance is due to the unique Mg-Al-C network which provides a favorable surface structure for the generation of unsaturated O<SUP>2−</SUP>. Among the samples tested, MgAl@C-1:2 shows the highest MgO carbonation conversion corresponding to 60% at 40°C with improved cyclic stability for 10 cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Resorcinol and formaldehyde used as soft templates and C-sources. </LI> <LI> The developed MgAl@C spheres show improved CO<SUB>2</SUB> sorption. </LI> <LI> MgAl@C shows 60% carbonation conversion at 40°C. </LI> <LI> The sorbents possess high thermal stability for up to 10 cycles. </LI> </UL> </P>
Hiremath, Vishwanath,Jadhav, Arvind H.,Lee, Hanyeong,Kwon, Soonchul,Seo, Jeong Gil Elsevier 2016 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.287 No.-
<P><B>Abstract</B></P> <P>Amino acid functionalized 1-methyl-3-ethyl-imidazolium based ionic liquid (IL) supported on ordered mesoporous silica (OMS-IL (AA)) were prepared via grafting method and were applied as solid sorbent for CO<SUB>2</SUB> adsorption–desorption. Four different kinds of amino acids (AA), including lysine (Lys), glycine (Gly), alanine (Ala), and proline (Pro) were selected in order to prepare different OMS-IL (AA) adsorbents. The developed solid adsorbents were characterized by using <SUP>29</SUP>Si-NMR, FT-IR, TGA, BET, SEM, TEM, and elemental analysis. The CO<SUB>2</SUB> adsorption–desorption studies were carried out using the thermogravimetric method with temperature swing assistance of the adsorbed CO<SUB>2</SUB>. Evaluation of CO<SUB>2</SUB> adsorption nature revealed that the adsorbents show fast kinetics, moderate chemisorption and easy desorption. Among the synthesized OMS-IL (AA), OMS-IL (Lys) showed the best CO<SUB>2</SUB> adsorptive performance corresponding to 0.61mmol/g at 25°C. The energy requirements for activation, adsorption and desorption are estimated by using different methods to meet its energy criteria. Further, the approach has been made to discuss the activity of selected amino acids, their effective loading, kinetics, and adsorption capacities in detail. DFT studies reveals that the energy required for CO<SUB>2</SUB> adsorption on IL (Lys) is high enough for CO<SUB>2</SUB> uptake (=−0.98eV). According to experiment and DFT calculations, a worthy correlation is identified between CO<SUB>2</SUB> adsorption capacity, adsorption energy, and the orbital localization, which determines the basic role of ILs over support to adsorbed CO<SUB>2</SUB> efficiently.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Amino acid functionalized ionic liquids immobilized on silica were synthesized. </LI> <LI> Moderate binding energy facilitates fast and reversible CO<SUB>2</SUB> adsorption–desorption. </LI> <LI> CO<SUB>2</SUB> adsorption capacity increased with increasing adsorption energy of CO<SUB>2</SUB>. </LI> <LI> Lysine with highest degree of band gap exhibited the best CO<SUB>2</SUB> adsorption capacity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Shavi, Raghavendra,Hiremath, Vishwanath,Seo, Jeong Gil Elsevier 2018 Molecular catalysis Vol.445 No.-
<P>Oxidative conversion of methane gas into value-added chemicals such as methanol is of great interest due to high economic feasibility of liquid fuel molecules for storage and transportation purpose. Activation and conversion of methane occur at very high temperatures due to its strong C-H bonding and hence the process is highly energy intensive. Therefore, homolytic cleavage of methane to produce CH3 and H radicals and subsequent conversion to methanol could be an alternative way to catalyze the reaction through a less energy-intensive process. In this work, radical-based conversion of methane to methanol was conducted in water-diluted 1-butyl-3-methylimidazolium chloride ionic liquid (IL) using metallic iron and copper as catalysts. The acidic IL, besides producing the high oxidation potential radicals from K2S2O8, enhanced their longevity. ZV Cu was found to be highly active in the reaction catalyzing with steady rate at a lower activation energy (E-a = 31.5 kJ/mol) and retains its oxidation state even after the reaction. On the other hand, ZV Fe, catalyzed the reaction with slightly slow initial rate ultimately resulting in moderate activation energy (40.77 kJ/mol). However, it was observed that ZV Fe fails to retain its oxidation state after reaction. (C) 2017 Elsevier B.V. All rights reserved.</P>
Jadhav, Arvind H.,Chinnappan, Amutha,Hiremath, Vishwanath,Seo, Jeong Gil American Scientific Publishers 2015 Journal of Nanoscience and Nanotechnology Vol.15 No.10
<P>Aluminum trichloride (AlCl3) impregnated molybdenum oxide heterogeneous nano-catalyst was prepared by using simple impregnation method. The prepared heterogeneous catalyst was characterized by powder X-ray diffraction, FT-IR spectroscopy, solid-state NMR spectroscopy, SEM imaging, and EDX mapping. The catalytic activity of this protocol was evaluated as heterogeneous catalyst for the Friedel-Crafts acylation reaction at room temperature. The impregnated MoO4(AlCl2)(2) catalyst showed tremendous catalytic activity in Friedel-Crafts acylation reaction under solvent-free and mild reaction condition. As a result, 84.0% yield of acyl product with 100% consumption of reactants in 18 h reaction time at room temperature was achieved. The effects of different solvents system with MoO4(AlCl2)(2) catalyst in acylation reaction was also investigated. By using optimized reaction condition various acylated derivatives were prepared. In addition, the catalyst was separated by simple filtration process after the reaction and reused several times. Therefore, heterogeneous MoO4(AlCl2)(2) catalyst was found environmentally benign catalyst, very convenient, high yielding, and clean method for the Friedel-Crafts acylation reaction under solvent-free and ambient reaction</P>
Bang, Yongju,Han, Seung Ju,Kwon, Soonchul,Hiremath, Vishwanath,Song, In Kyu,Seo, Jeong Gil American Scientific Publishers 2014 Journal of Nanoscience and Nanotechnology Vol.14 No.11
<P>Nano-structured alkaline-earth metal oxide adsorbents (denoted as MgO-Al2O3 and CaO-Al2O3) were prepared by an epoxide-driven one-pot sol-gel method, and they were applied to the dynamic and static CO2 adsorption. For comparison, a nano-structured aluminum oxide adsorbent (denoted as Al2O3) was also prepared by a similar method. MgO-Al2O3 adsorbent exhibited a well-developed mesopore structure through the formation of MgAl2O4 spinel phase, whereas CaO-Al2O3 adsorbent was composed of nano-sized CaO and CaAl2O4, resulting in a pore plugging. It was revealed that total basicity increased in the order of Al2O3 (0.11 mmol-CO2/g) < MgO-Al2O3 (0.37 mmol-CO2/g) < CaO-Al2O3, (1.21 mmol-CO2/g), which is in concurrent with adsorption energy obtained from DFT calculations. However, it was found that both basicity and base strength of the adsorbents played an important role in determining the CO2 adsorptive performance at different operating temperature. Among the adsorbents tested, MgO-Al2O3, which mostly retained medium basic sites, exhibited a best CO2 adsorptive performance at 200 degrees C. Furthermore, the experimental results are well supported by theoretical estimation, suggesting a useful design method of adsorbents for facile and regenerative adsorption in the applications of CO2 capture.</P>