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Item The direct conversion of benzene to phenol by hydroxylation with hydrogen peroxide was carried out over various transition metals impregnated on MCM-41 and activated carbon. Copper-, iron-, and vanadium-impregnated on activated carbon gave better yields of phenol when compared to the corresponding reactions using cobalt-, nickel-, manganese-, and titanium-impregnated catalysts. Comparison of the MCM-41 and activated carbon-supported catalysts showed that activated carbon-supported catalysts gave a higher yield of phenol than did the MCM-41-supported catalysts. The activity of the transition metals supported on activated carbon in the production of phenol was V > Fe > Cu; the corresponding activity of the transition metals supported on MCM-41 was Cu > Fe > V. In addition to the role of transition metals in catalyzing the hydroxylation reaction, the hydrophobic nature of the activated carbon surface seems to enhance the performance of these catalysts relative to the MCM-41-supported catalysts.(Benzene hydroxylation to phenol catalyzed by transition metals supported on MCM-41 and activated carbon) Choi, J.-S.; Kim, T.-H.; Saidutta, M.B.; Sung, J.-S.; Kim, K.-I.; Jasra, R.V.; Song, S.-D.; Rhee, Y.-W.2004Item Novel Co-Ni-graphene composite electrodes for hydrogen production(Royal Society of Chemistry, 2015) Subramanya, B.; Ullal, Y.; Shenoy, S.U.; Bhat, D.; Hegde, A.C.Active, stable and cost-effective electrocatalysts are key to water splitting for hydrogen production through electrolysis. Herein, we report the facile preparation of highly porous Co-Ni-graphene (Co-Ni-G) composite electrodes by electrodeposition for electrocatalytic applications. The incorporation of graphene into the Co-Ni matrix enhances the catalyst's activity for the hydrogen evolution reaction (HER) in an alkaline solution. The best coating exhibits a maximum current density of -850 mA cm-2 at -1.6 V, which is approximately 4 times better than that of the binary Co-Ni alloy indicating higher activity for hydrogen production. The addition of graphene to an electrolyte bath results in a porous encapsulated bundle of alloy nano-particles within the graphene network which effectively increases the electrochemically active surface area. As indicated by XPS analysis results, on addition of graphene the Co(0) and Ni(0) content in the deposit increases and as a result both cobalt/cobalt oxide and nickel/nickel oxide sites are evenly distributed on the Co-Ni-G electrode surface which is responsible for increased HER activity. The Tafel slope analysis showed that the HER follows a Volmer-Tafel mechanism. The structure-property relationship of the Co-Ni-G composite coating has been discussed by interpreting field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis results. © The Royal Society of Chemistry 2015.Item Multi-wall carbon nanotube-NiO nanoparticle composite as enzyme-free electrochemical glucose sensor(Elsevier, 2015) Prasad, R.; Badekai Ramachandra, B.R.We report a simple, solvent-free method to decorate multi-walled carbon nanotubes (MWCNTs) with nickel oxide nanoparticles (NiO-NPs). The as prepared NiO-MWCNT composite were characterised by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The enzyme-free modified carbon paste electrode (CPE) was fabricated using as-synthesised composite material and investigated for glucose sensing. The 10% NiO-MWCNTs composites sensor showed excellent electro-catalytic activity towards direct glucose oxidation. The sensitivity of this sensor is found to be 1696 ?A mM-1 cm-2 and 122.1 ?A mM-1 cm-2 and the limit of detection (LOD) was found to be 11.04 nM and 31 ?M for the linear response over glucose concentration ranging from 1-200 ?M to 0.5-9.0 mM, respectively. Furthermore, the 10% NiO-MWCNTs sensor also showed excellent anti-interference ability, high stability and good reproducibility. Hence, due to simple method of material preparation, easy sensor fabrication and excellent electro catalytic activity towards glucose oxidation, the 10% NiO-MWCNT/CPE is a potential material for the development of enzyme-free sensor for reliable glucose determination. © 2015 Elsevier B.V. All rights reserved.Item Immobilized magnetic nano catalyst for oxidation of alcohol(Elsevier, 2015) Bhat, P.B.; Rajarao, R.; Sahajwalla, V.; Badekai Ramachandra, B.R.Covalent attachment of Schiff base on magnetic nanoparticles yielded good selectivity for oxidation of alcohols. The ferromagnetic interaction in the complex added comprehensive advantage in enhancing the catalytic activity of the nanocatalyst. A greener approach for alcohol oxidation was achieved in solventless method with good yield (>78%). Leaching experiments confirmed a strong interaction between magnetic support and complex. The catalyst showed significant conversion even after 5 catalytic runs. © 2015 Elsevier B.V. All rights reserved.Item Electrolytic Synthesis and Characterization of Electrocatalytic Ni-W Alloy(Springer New York LLC barbara.b.bertram@gsk.com, 2015) Elias, L.; Scott, K.; Hegde, A.Inspired by the more positive (about 0.38 V nobler) discharge potential of hydrogen on Ni-W alloy compared to that on both Ni and W, a Ni-W alloy has been developed electrolytically as an efficient electrode material for water electrolysis. The deposition conditions, for peak performance of the electrodeposits for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH medium have been optimized. Electrocatalytic activity of the coatings, deposited at different current densities (c.d.’s) for water splitting reactions of HER and OER was tested by cyclic voltammetry and chronopotentiometry. It was found that Ni-W alloys deposited, at 4.0 A/dm2 (having about 12.49 wt.% W) and 1.0 A/dm2 (having about 0.95 wt.% W) are good electrode materials as cathode (for HER) and anode (for OER), respectively. A dependency of the electrocatalytic activity for HER and OER with relative amount of Ni and W, in the deposit was found. The variation of electrocatalytic activity with W content showed the existence of a synergism between high-catalytic property of W (due to low hydrogen overvoltage) and Ni (having increased adsorption of OH? ions), for hydrogen (as cathode) and oxygen (as anode) evolution, respectively. Electrocatalytic activities of the coatings, developed at different c.d.’s were explained in the light of their phase structure, surface morphology, and chemical composition, confirmed by XRD, FESEM, and EDX analysis. The effect of c.d. on thickness, hardness, composition, HER, and OER was analyzed, and results were discussed with possible mechanisms. © 2015, ASM International.Item Modification of Ni-P alloy coatings for better hydrogen production by electrochemical dissolution and TiO2 nanoparticles(Royal Society of Chemistry, 2016) Elias, L.; Hegde, A.This work reports the modification of Ni-P alloy coatings for better hydrogen production by electrochemical dissolution and TiO2 nanoparticle incorporation. The first part is devoted to optimization of a new citrate bath for the development of an efficient electroactive Ni-P electrode material by electrodeposition, using glycerol as an additive. The Ni-P alloys developed at 4.0 A dm-2 and 2.0 A dm-2 were found to be good for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively as demonstrated by cyclic voltammetry (CV) and chronopotentiometry (CP) methods. The Ni-P alloy showing good catalytic activity for HER is found to be less active for OER and vice versa. The unique electrocatalytic property of the coatings was attributed to its structure, morphology and composition, confirmed by XRD, SEM and EDS analyses. In the second part, the electrocatalytic activity of Ni-P alloy coatings for HER has been improved further by anodic dissolution and TiO2 nanoparticle incorporation. Drastic improvement in the electrocatalytic activity for HER was found in both anodically treated and Ni-P-TiO2 composite coatings, compared to as-coated Ni-P alloys. The highest electrocatalytic character of the Ni-P-TiO2 composite coating was attributed to a greater number of electroactive centres, affected by TiO2 nanoparticle incorporation, and experimental results are discussed. © The Royal Society of Chemistry 2016.Item Novel RGO-ZnWO4-Fe3O4 nanocomposite as high performance visible light photocatalyst(Royal Society of Chemistry, 2016) Mohamed, M.M.J.; Shenoy, U.S.; Bhat, D.K.A novel RGO-ZnWO4-Fe3O4 nanocomposite is synthesized by a microwave irradiation method and its catalytic activity for the photo degradation of Methylene Blue (MB) is investigated. The prepared nanocomposites are characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Raman spectroscopy, photoluminescence spectroscopy (PL) and UV-visible spectroscopy. The visible light photocatalytic activities of the prepared nanocomposites are investigated using a MB dye solution. It is noteworthy that RGO-ZnWO4-Fe3O4 nanocomposites exhibited relatively high photocatalytic activity compared to ZnWO4-RGO and pure ZnWO4 on MB in aqueous solution. This enhanced rate is due to the ability of the graphene in the RGO-ZnWO4-Fe3O4 composite to support carrier exploitation efficiently by tolerating the photo excited electron-hole pairs and thus encouraging oxidative degradation of the pollutants. This work could be extended to other organic pollutants as well and could provide new insights into ternary nanocomposites as high performance photocatalysts and their application in waste water treatment. © 2016 The Royal Society of Chemistry.Item Partial purification and characterization of L-asparaginase from an endophytic Talaromyces pinophilus isolated from the rhizomes of Curcuma amada(Elsevier, 2016) Krishnapura, P.R.; Belur, P.D.l-Asparaginase is a commercially significant enzyme. There exists a demand for a broad variety of microbial l-asparaginases with characteristics compatible with its different applications. Endophytic microorganisms, in particular are emerging as potential sources of l-asparaginases. The current work involves partial purification and characterization of l-asparaginase from Talaromyces pinophilus, an endophytic fungus isolated from the rhizomes of Curcuma amada. Maximum enzyme activity could be achieved at pH 8.0 and with temperature 28 °C. The enzyme Exhibits 95 % and 98% of its total activity at physiological pH and temperature, respectively. The enzyme activity is largely unhindered in the presence of metal ions such as Ca2+, Cu2+, Fe2+, Mg2+, Mn2+, Zn2+. Increase in the enzyme activity in the presence of thiol groups and reduction in the same upon addition of thiol blockers indicates the involvement of cysteine in the enzyme's catalytic activity. The enzyme is a heterodimer of 62 kDa and 39 kDa. The enzyme has a Km of 6.4 mM, its turnover number towards l-asparagine is 286.3 s-1. The enzyme has 16% glutaminase activity; its Km towards glutamine is 13.3 mM and turnover number is 54.6 s-1. Our results highlight that l-asparaginase from endophytic Talaromyces pinophilus could be considered as potential candidate for clinical and industrial trials, owing to its efficiency and biochemical properties. To the best of our knowledge, this is the first report on partial purification and characterization of L-asparaginase from an endophyte. © 2015 Elsevier B.V. All rights reserved.Item Fabrication, characterization and catalytic activity of ?-MnO2 nanowires for dye degradation of reactive black 5(Elsevier B.V., 2016) Ramesh, M.; Nagaraja, H.S.; Rao, M.P.; Anandan, S.; Huang, N.M.?-MnO2 nanowires (NWs) prepared by hydrothermal method are characterized using XRD and FT-IR. The crystallite size, surface area of NWs increases, whereas dislocation density and band gap decreases with an increase in oxidizer molarity. The band gap decreases from 2.55 to 1.27 eV. The above observations correlate well with the enhanced catalytic activity of MnO2 NWs for degradation of azo dye reactive black 5 (RB5). About 70% of the dye were successfully removed in 60 min using 20 mg of MnO2 NWs in the presence of 6 mL of H2O2. MnO2 NWs show a good reusability, suggesting it as an effective and recyclable catalyst. © 2016 Elsevier B.V. All rights reserved.Item 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.