02925nas a2200229   4500008004100000022001400041245014300055210006900198260007300267300001000340490000800350520203500358653001702393653001802410653002702428653001702455653002702472100002502499700002602524700001602550856012902566       2010                        eng d  a1381-116900aProbing lewis acidity and reactivity of Sn- and Ti-beta zeolite using industrially important moieties: a periodic density functional study0 aProbing lewis acidity and reactivity of Sn and Tibeta zeolite us  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG  a36-430 v3293 a<p>The Lewis acidic nature and reactivity of two industrially important catalysts, viz.. Sn and Ti substituted beta zeolite (T-BEA) are analyzed using a unique combination of structural parameters, energetics and reactivity descriptors. To achieve this purpose, we adsorb the industrially important moieties (L) namely NH(3), H(2)O, CH(3)OH, CH(3)CN on the active sites of T-BEA. The calculations were performed using a periodic density functional method where the valence electrons are described using a plane wave basis set in conjunction with pseudo-potentials for the core electrons. The analysis of the structural properties of these complexes reveals that TO(4) shows typical characteristic splitting 120 degrees/90 degrees, close to bipyramidal geometry as compared to tetrahedral symmetry observed in the bare T-BEA. This is associated with small variations in the framework bond lengths (&gt;= 0.08 angstrom) and a substantially large variation of bond angles (&lt;= 10 degrees) in all the ligand-zeolite complexes. Further in both cases of Sn and Ti substituted beta zeolite, ligand interacts at optimum inter-atomic bond distance. Our interaction energies show that adsorption of all ligand moieties is stronger at Sn center than that of Ti. In general, the order of stability of the different T-BEA adducts is NH(3) &gt; H(2)O &gt; CH(3)OH &gt; CH(3)CN. The ligand interaction is associated with the corresponding bond elongation and bond reduction of the adsorbed molecules on catalyst active site, which can be taken as measure of red or blue shifted frequencies. Finally, the global descriptors of reactivity justify the fact that soft acid, Sn-BEA, interacts strongly with soft bases following the Pearson's HSAB principle. However, hard acid, Ti-BEA interacts with soft bases to form a stable Lewis adduct. Furthermore, the HOMO-LUMO gap of all Sn-BEA-L adducts is lower than that of Ti-BEA-L adducts indicating to its higher Lewis acidic nature compared to Ti-BEA. (C) 2010 Elsevier B.V. All rights reserved.</p>10aBeta zeolite10aLewis acidity10aLigand-zeolite complex10aPeriodic-DFT10aReactivity descriptors1 aKulkarni, Bhakti, S.1 aKrishnamurty, Sailaja1 aPal, Sourav  uhttp://library.ncl.res.in/content/probing-lewis-acidity-and-reactivity-sn-and-ti-beta-zeolite-using-industrially-important-002276nas a2200253   4500008004100000022001400041245010300055210006900158260000900227300001100236490000900247520140000256653002301656653001601679653001901695653001601714653004201730653002101772100002901793700001701822700002701839700002601866856013001892       2019                        eng d  a2210-271X00aProbing the catalytic activity of pristine and doped Pd and Ni metal clusters towards H2O molecule0 aProbing the catalytic activity of pristine and doped Pd and Ni m  cDEC   a1126240 v11703 a<p>Electrolysis of H2O to produce molecular hydrogen, the most environment friendly and energy efficient fuel, using cost effective catalysts is one of the major global research challenges. To date, Pt remains the best suitable and yet highly expensive electro-catalyst for hydrogen evolution reaction. Design of an alternative cost-effective catalyst requires a fundamental molecular level understanding of the water molecule adsorption and its activation. In that context, we examine the adsorption and activation of water molecule on model alternative catalysts namely, Ni-6 and Pd-6 clusters using density functional theory based methodology. Ni-6 and Pd-6 clusters and their singly doped counterparts are used for this study. Mo, W, Fe, Co and Cu are used as doping elements. To quantify the influence of medium (neutral and alkaline) on the activation of the water molecule, Ni based clusters are considered in neutral and anionic states, respectively. The activity of these clusters towards H2O molecule is evaluated in terms of the adsorption energy, charge transfer, bandgap, red shift in O-H stretching frequency and dissociation barriers for H2O. The studies demonstrate that doping with Co in all the studied clusters (Pd-6, Ni-6 and anionic Ni-6) increases their activity. Best activity is noted for Fe doped neutral Ni b clusters with a dissociation barrier of 5.76 kcal/mol.</p>
10aActivation barrier10aNi clusters10aO-H activation10aPd clusters10aRed shift of O-H stretching frequency10aWater adsorption1 aSamal, Pragnya, Paramita1 aJoshi, Krati1 aKaliaperumal, Selvaraj1 aKrishnamurty, Sailaja  uhttp://library.ncl.res.in/content/probing-catalytic-activity-pristine-and-doped-pd-and-ni-metal-clusters-towards-h2o-molecule00846nas a2200241   4500008004100000022001400041245010800055210006900163260000900232300001400241490000700255653002100262653001800283653001400301653001900315100002500334700002700359700002600386700001700412700002300429700003000452856012200482       2024                        eng d  a2044-475300aPolyvalent interaction and confinement to suppress polysulfide dissolution and improve electrocatalysis0 aPolyvalent interaction and confinement to suppress polysulfide d  cJUN   a3416-34230 v1410acathode material10aHIGH-CAPACITY10aParticles10aSULFUR CATHODE1 aBharathkumar, H., J.1 aShivankar, Bhavana, R.1 aKrishnamurty, Sailaja1 aChen, Dehong1 aCaruso, Rachel, A.1 aKrishnamoorthy, Kothandam  uhttp://library.ncl.res.in/content/polyvalent-interaction-and-confinement-suppress-polysulfide-dissolution-and-improve