Browsing by Author "Badekai Ramachandra, B."

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A catalytic process for the selective oxidation of alcohols by copper (II) complexes
(2011) Ramakrishna, D.; Badekai Ramachandra, B.
Novel copper (II)-N-(2-pyridyl)-N'-(5-R-salicylidene) hydrazine triphenylphosphine complexes have been synthesized and characterized. The complexes were effective in the catalytic oxidation of primary and secondary alcohols in presence of periodic acid (H5IO6) as oxidant. The oxidation reactions were carried out in acetonitrile. Electrochemical electron transfer study reveals CuII-CuI reduction in methanolic solutions. A mechanistic study of the above reactions has been proposed. © 2011 Elsevier B.V. All rights reserved.
All optical nonlinear and switching characteristics of a novel ruthenium complex
(Elsevier B.V., 2014) Manjunatha, K.B.; Dileep, R.; Umesh, G.; Satyanarayan, M.N.; Badekai Ramachandra, B.
Third-order nonlinear optical properties of a novel ruthenium complex (2-thioxo-1,3-dithiole-4,5-dithiolato) triphenylarsenic Ru(III), have been investigated by employing Z-scan and DFWM techniques. The compound shows self-defocusing effect. Its nonlinear refractive index, third-order nonlinear optical susceptibility and the second-order hyperpolarizability are seen to be of the order of 10-9, 10-10 and 10-30 esu respectively. The nonlinear absorption coefficient is of the order of 10 -9 m/W. This material exhibits good optical power limiting capability which is seen to occur due to reverse saturable absorption. Experiments on all-optical switching action indicate that the sample can function as an optical inverter or a NOT gate. © 2014 Elsevier B.V. All rights reserved.
Binder free MoO3/multiwalled carbon nanotube thin film electrode for high energy density supercapacitors
(2013) Aravinda, L.S.; Bhat, K.; Badekai Ramachandra, B.
MoO3/multiwalled carbon nanotube (MWCNT) composites were prepared by Magnetron sputtering in Ar/O2 atmosphere. This will provide a greener alternative for the fabrication of binder free composite electrode for supercapacitor applications. MWCNT provides good support for the growth of MoO3 thin films. This integrated composite electrode exhibited specific capacitance of 93 F g-1 and a corresponding energy density of 7.28 Wh kg-1 in non-aqueous electrolyte, which is almost fourfold increase compared to the bare MWCNT. Also the electrode maintains high power density of 4930 W kg-1 at high current rates, suggesting a potential energy storage material for portable and consumer electronics. © 2013 Elsevier Ltd. All rights reserved.
Catalytic oxidation of alcohols by nickel(II) Schiff base complexes containing triphenylphosphine in ionic liquid: An attempt towards green oxidation process
(2010) Ramakrishna, D.; Badekai Ramachandra, B.; Karvembu, R.
A series of square planar nickel(II) complexes containing N,O donor Schiff base ligand, i.e. N-(2-pyridyl)-N?-(5-substituted-salicylidene)hydrazine and triphenylphosphine, have been synthesized and characterized by analytical and spectral methods. Catalytic activities of all the complexes have been studied for the oxidation of alcohols in ionic liquid media using NaOCl as oxidant. © 2009 Elsevier B.V. All rights reserved.
Cobalt complexes in [EMIM]Cl - A catalyst for oxidation of alcohols to carbonyls
(2010) Ramakrishna, R.; Badekai Ramachandra, B.
A coordination complex system consisting of Cobalt (II)-Schiff bases with triphenylphosphine were synthesized and characterized. These catalysts were effective in the oxidation of primary and secondary alcohols. The oxidation reactions were carried out in ethyl-methyl-imidazolium ionic liquid in presence of NaOCl. Higher catalytic activity was observed for CoL1. © 2009 Elsevier B.V. All rights reserved.
Cobalt pincer complex catalyzed Suzuki-Miyaura cross coupling – A green approach
(Elsevier B.V., 2017) Kumar, L.M.; Badekai Ramachandra, B.
A series of cobalt complexes with tridentate pincer ligands were synthesized to study their catalytic activity in Suzuki-Miyaura coupling reactions. Cobalt complexes, C-1, C-2, C-3 bearing asymmetrical PNCOP pincer ligand [C6H4-1-(NHPPh2)-3-(OPPh2)] (L-1) and symmetrical PNCNP, PNNNP pincer ligands [C6H4-2,6-(NHPPh2)2] (L-2) and [C5H3N-2,6-(NHPPh2)2] (L-3) were synthesized by the reaction of diphenylchlorophosphine with m-aminophenol, m-phenylenediamine and 2,6-diaminopyridine respectively in a 1:2 ratio in the presence of triethylamine as a base and tetrahydrofuran as solvent media. The synthesized complexes were examined for their C-C coupling efficiency in cross-coupling between phenyl boronic acid and para substituted bromobenzenes. Effect of variation of the ligand on the catalytic activity of cobalt pincer complex was explored based on the coupling yields. It is observed that as the number of ‘N’ atoms increases in the side arm of the ligand, the donating ability of the ligand increases which leads to the increased catalytic activity of the complex. The symmetrical PNNNP pincer complex (C-3) was found to be more effective as a catalyst among the complexes synthesized and reported in the present study. © 2016 Elsevier B.V.
Comparison of structural health assessment capabilities in epoxy - Carbon black and epoxy - Carbon nanotube nanocomposites
(2014) Inam, F.; Badekai Ramachandra, B.; Luhyna, N.; Vo, T.
A novel method for comparing structural health of different types of brittle epoxy nanocomposites filled with carbon nanostructured fillers is presented. Epoxy - 0.2 vol% carbon black (CB) and epoxy - 0.2 vol% carbon nanotube (CNT) nanocomposite bars were prepared by calendering and thermal curing. Nanocomposite bars were subjected to Vickers diamond indentation to produce sub-surface damage. Electrical conductivities were analysed by 4-point method to estimate the structural damage caused by indentation. For comprehensive comparison, fracture toughness and percolation threshold were analysed as well. Because of the systematically induced indentation damage, a sharp decrease of 89% was observed in the electrical conductivity of epoxy - CNT nanocomposite as compared to 25% in the electrical conductivity of epoxy - CB nanocomposite. CNTs impart superior damage sensing capability in brittle nanocomposite structures, in comparison to CB, due to their high aspect ratio (fibrous nature) and high electrical conductivity. © BME-PT.
Effect of shot peening coverage on surface nanostructuring of 316L stainless steel and its influence on low temperature plasma-nitriding
(ASTM International, 2017) Jayalakshmi, M.; Badekai Ramachandra, B.; Bhat, K.U.
Air-blast shot peening (ABSP) is a cost effective and industrially viable technique to produce nanostructured surface layer on metallic materials. In the present study, 316L stainless steel samples were subjected to shot peening at different peening coverage, from conventional to severe peening. Nanocrystalline structure was observed on the sample surface after peening and mechanical twins; intersection of multidirectional twins producing rhombic blocks were observed in the subsurface layer. Peening process led to the formation of strain induced martensite (?'), and its fraction was found to increase with the coverage. Depth of nanostructured layer and surface microhardness also increased with the increase in coverage, whereas surface roughness followed an opposite trend. Both peened and un-peened samples were subjected to plasma nitriding at 400°C for 4 h. Uniform and appreciably high case depth of about 45 ?m was observed in severely pre-peened (1000 % coverage) sample after nitriding treatment. No precipitation of CrN was observed. This highlights the marked influence of severe shot peening as a pre-treatment for low temperature plasma nitriding of austenitic stainless steels. © © 2017 by ASTM International.
Effective oxidation of alcohols by Iron(III)-Schiff base-triphenylphosphine complexes
(2010) Rani, S.; Badekai Ramachandra, B.
Iron(III)-Schiff base-triphenylphosphine complexes catalyze the oxidation of alcohols to their corresponding carbonyl compounds in presence of hydrogen peroxide in good yields. © 2010 Elsevier Ltd. All rights reserved.
Effective oxidation of alcohols with H5IO6 catalyzed by nickel(II) schiff base complexes
(2010) Ramakrishna, D.; Badekai Ramachandra, B.
Nickel(II)-Schiff base-triphenylphosphine complexes catalyze oxidation of alcohols to carbonyls in presence of minimum amount of periodic acid. The catalytic oxidation was developed in mild conditions and showed good yields. The effects of temperature, time, and concentrations of catalyst and co-oxidant were studied. Higher catalytic activity has been observed for NiL1 compared to the other complexes.Copyright © Taylor & Francis Group, LLC.
Green approach to synthesize multi-walled carbon nanotubes by using metal formate as catalyst precursors
(2013) Rajarao, R.; Badekai Ramachandra, B.
The multi-walled nanotubes (MWNTs) have been synthesized in large scale by using metal formate as catalyst precursors. The calcium carbonate is used as catalyst support, it is chosen because of its non toxic and easily soluble nature. The synthesis was carried out by chemical vapor deposition method for 15 min under optimized conditions. The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD) method. The purity of the as grown products and purified products were determined by thermal analysis. The obtained yield of MWNTs was about 8300 wt% relative to the nickel catalyst. This synthesis route avoids the lengthy process of calcination and reduction for the preparation of catalysts hence this method is more economical. This economical and environmental friendly synthesis route can be used for synthesizing MWNTs in large scale. Copyright © 2013 American Scientific Publishers All rights reserved.
Green conversion of alcohols to carbonyls catalyzed by novel ruthenium-Schiff base-triphenylphosphine complexes
(2011) Ramakrishna, D.; Badekai Ramachandra, B.
A series of new RuII-Schiff base complexes of containing Ph 3P has been prepared and characterized. The complexes have been used as catalysts for the oxidation of alcohols in [EMIM]Cl ionic liquid-NaOCl system. Higher catalytic activity was found for RuL1. A plausible mechanism has been proposed. © 2010 Elsevier B.V. All rights reserved.
High power density and improved H2 evolution reaction on MoO3/Activated carbon composite
(Elsevier Ltd, 2020) Sangeetha, D.N.; Holla, R.S.; Badekai Ramachandra, B.; Muthu, M.
The formation of hexagonal MoO3 (h- MoO3) microrods was favoured at lower pH in the hydrothermal synthesis method. Symmetric and Hybrid supercapacitors were fabricated using h-MoO3/plastic bottle derived activated carbon (PAC) composite in 1 M Na2SO4 aqueous electrolyte. The operating voltage for the aqueous electrolyte was maximized to 1.6 V with this combination. The wide operating voltage led to a maximum specific capacitance of 211 Fg-1, power density of 287 W kg?1 and 79% efficiency even at 5000 charge-discharge cycles for the hybrid supercapacitor combination. The combined effect of PAC micropores along with the 1-D rod-shaped h-MoO3, helped in faster charge-transfer, hence increasing the efficiency of supercapacitors. Further, the composites of defective PAC (PDAC) together with the h-MoO3 when tested for hydrogen evolution reactions (HER), provided lesser onset potential and Tafel slope values of ?0.23 mV and ?93 mVdec?1. There was a change in the structural environment of carbon due to the heteroatom doping and dedoping producing defects in PAC, termed as PDAC. These defects together with the hexagonal microrods of MoO3 provided fast electron transfer towards hydrogen adsorption/desorption hence effectively producing H2. © 2019 Hydrogen Energy Publications LLC
High yield synthesis of carbon nanofibers in an environmental friendly route
(Springer Nature, 2011) Ravindra, R.; Badekai Ramachandra, B.
An environmental friendly route for the high yield synthesis of carbon nanofibers (CNFs) has been developed. CNFs have been synthesized using nickel formate as catalyst precursor at 680°C using chemical vapor deposition method. Upon pyrolysis this catalyst precursor yields metal catalyst nanoparticles directly. The sodium chloride and potassium chloride was used as catalyst support, it was chosen because of its non-toxic and water soluble nature. The problems such as detrimental effect, environment and even cost has been avoided by using water soluble supports. The structure of the products was characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and X-ray diffraction method. The purity of as grown products and purified products was determined by thermal analysis. Here, we report the 7,800 and 7,200 wt% yield of CNFs synthesized over NaCl and KCl support. This synthetic route can be used for the large scale synthesis in industries. © 2011, The Author(s).
Investigation of nonlinear optical and all-optical switching properties of novel ruthenium complex
(IEEE Computer Society help@computer.org, 2012) Manjunatha, K.B.; Shettigar, S.; Rajarao, R.; Umesh, G.; Badekai Ramachandra, B.
The nonlinear optical, optical limiting and all-optical switching properties of novel ruthenium complex doped PMMA film were investigated at 532 nm. The investigations show that the complex is a potential molecule for photonic applications. Â© 2012 OSA.
Investigation of Nonlinear Optical and All-Optical Switching Properties of Novel Ruthenium Complex
(Optica Publishing Group (formerly OSA), 2012) Manjunatha, K.B.; Shettigara, S.; Rajarao, R.; Umesh, G.; Badekai Ramachandra, B.
The nonlinear optical, optical limiting and all-optical switching properties of novel ruthenium complex doped PMMA film were investigated at 532 nm. The investigations show that the complex is a potential molecule for photonic applications. Â© 2012 OSA - The Optical Society. All rights reserved.
Large-scale synthesis of high purity carbon nanotubes by novel catalytic route
(2013) Rajarao, R.; Badekai Ramachandra, B.
Large-scale production of carbon nanotubes is achieved by using metal formates as catalyst precursors by chemical vapor deposition method. The calcium carbonate is used as catalyst support, it is chosen because of its nontoxic and easily soluble nature. The synthesis was carried out at 700°C in quartz reactor for 15 min. The obtained yield of carbon nanotubes was about 96 times relative to the Ni/Co catalyst. The lengthy process of calcination and reduction for the preparation of catalysts is avoided in this method. This economical synthesis route is more efficient and environmentally friendly. Copyright © Taylor & Francis Group, LLC.
Magnetron sputtered MoO3/carbon nanotube composite electrodes for electrochemical supercapacitor
(Elsevier B.V., 2013) Aravinda, L.S.; Nagaraja, K.K.; Bhat, K.; Badekai Ramachandra, B.
Molybdenum oxide (MoO3) has been deposited on multiwalled carbon nanotubes (MWCNTs) using DC reactive magnetron sputtering of molybdenum for supercapacitor applications. The deposits of MoO3 have been developed under different intervals of time. The structure and surface morphology of the deposits have been characterized by means of X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FESEM). X-ray diffraction peaks of the composite films reveal the formation of crystalline structure of MoO3. The electrochemical performance of the composite films was studied using cyclic voltammetry (CV), galvanostatic charge discharge and electrochemical impedance spectroscopy measurements. The composite film exhibits maximum specific capacitance of 70 F g-1 at a scan rate of 10 mV s-1 in 1 M Na2SO4 electrolyte. The nanocomposite electrode material shows specific capacitance which is almost four fold increase with respect to that of bare MWCNTs. The effect of coating duration on specific capacitance has been studied. The nanocomposite film is found to display good cycleability, even up to 1000 cycles. © 2013 Elsevier Inc. All rights reserved.
Methanol selective oxidation to formaldehyde over a modified Fe-Mo catalyst with two different stoichiometric (Mo/Fe atomic ratio = 1.5 and 3.0) was studied experimentally in a fixed bed reactor over a wide range of reaction conditions. The physicochemical characterization of the prepared catalysts provides evidence that Fe2(MoO4)3 is in fact the active phase of the catalyst. The experimental results of conversion of methanol and selectivity towards formaldehyde for various residence times were studied. The results showed that as the residence time increases the yield of formaldehyde decreases. Selectivity of formaldehyde decreases with increase in residence time. This result is attributable to subsequent oxidation of formaldehyde to carbon monoxide due to longer residence time.
(Selective oxidation of methanol to formaldehyde using modified iron-molybdate catalysts) Kim, T.-H.; Badekai Ramachandra, B.; Choi, J.-S.; Saidutta, M.B.; Choo, K.-Y.; Song, S.-D.; Rhee, Y.-W.
2004
Molybdenum based mixed oxide containing Mo0.65V 0.25W0.10 was investigated for the partial oxidation of methanol. The structural property and catalytic activity of the mixed oxide catalyst was studied by surface area (BET), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD). The thermal activation of the catalyst resulted increase in the conversion of methanol and the selectivity to formaldehyde. The thermal activation of the MoVW mixed oxide in nitrogen atmospheres induces partial crystallization of a Mo5O14-type oxide at 813 K. The SEM images of the thermally activated catalyst show needle like particles. These particles were agglomerates of platelet-like crystallites of a few hundreds of nanometers in size. SEM and EDX techniques show that the mixed oxide is characterized by an inhomogeneous elemental distribution on the length scale of a few microns. XRD of the thermally activated catalyst showed a nanocrystalline material identified as a mixture of Mo5O 14, MoO3 and MoO2-type MoVW oxides. The catalytic activity of the MoVW mixed oxide show a good conversion of methanol and selectivity to formaldehyde. © 2005 Springer Science+Business Media, Inc.
(Partial oxidation of methanol to formaldehyde on molybdenum based mixed oxide catalyst) Badekai Ramachandra, B.; Choi, J.-S.; Choo, K.-Y.; Sung, J.-S.; Song, S.-D.; Kim, T.-H.
2005