Publications by authors named "Suresh Babu Kalidindi"

25 Publications

  • Page 1 of 1

Hybrids of Pd Nanoparticles and Metal-Organic Frameworks for Enhanced Magnetism.

J Phys Chem Lett 2021 May 13;12(19):4742-4748. Epub 2021 May 13.

Max Planck Institute for Intelligent Systems, Stuttgart D-70569, Germany.

Nonmagnetic Pd exhibits ferromagnetism in the nanosize regime. Various stabilization agents, including surfactants, metal oxide supports, polymers, and porous materials (e.g., metal-organic frameworks (MOFs)), have been employed to prevent the agglomeration of metal nanoparticles. However, magnetic properties are greatly affected by the structural and electronic changes imposed by these stabilizing agents. In particular, metal-MOF hybrids ([email protected]) have reduced magnetic properties, as reported by several authors. Herein, we report the enhancement in magnetic properties resulting from the combination of magnetic Pd NPs with UiO-66(Hf), which exhibits ferromagnetism, and the corresponding modifications in the hybridized structures. These hybridized structures are found to be strongly ferromagnetic, showing high magnetization and coercivity. We observed that the magnetic property is enhanced by 2 to 3 times upon including the Pd NPs on the surface of a UiO-66(Hf) shell support. For a fundamental understanding, the magnetization (- data) of the hybridized structure is analyzed with a modified Langevin function.
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http://dx.doi.org/10.1021/acs.jpclett.1c01108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8279731PMC
May 2021

Nanocomposite Hydrogel of [email protected] and Laponite : Size-Selective Hydrogenation Catalyst under Mild Conditions.

Chemistry 2021 Feb 18;27(10):3268-3272. Epub 2021 Jan 18.

Molecular Materials Laboratory, Chemistry and Physics of Materials Unit, School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, India.

The composite hydrogel of a nanoscale metal-organic framework (NMOF) and nanoclay has emerged as a new soft-material with advanced properties and applications. Herein, we report a facile synthesis of a hydrogel nanocomposite by charge-assisted self-assembly of [email protected] nanoparticles with Laponite nanoclay which coat the surface of [email protected] nanoparticles. Such surface coating significantly enhanced the thermal stability of the ZIF-8 compared to the pristine framework. Further, the [email protected]+LP hydrogel nanocomposite shows better size-selective catalytic hydrogenation of olefins than [email protected] nanoparticles based on selective diffusion of the substrate.
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http://dx.doi.org/10.1002/chem.202004345DOI Listing
February 2021

Transfer hydrogenation of alkynes into alkenes by ammonia borane over Pd-MOF catalysts.

Dalton Trans 2020 Apr;49(16):5024-5028

Materials Science Division, Poornaprajna Institute of Scientific Research, Devanahalli, Bangalore Rural-562164, India.

Ammonia borane with both hydridic and protic hydrogens in its structure acted as an efficient transfer hydrogenation agent for selective transformation of alkynes into alkenes in non-protic solvents. Catalytic synergy between the μ3-OH groups of the UiO-66(Hf) MOF and Pd active sites in Pd/UiO-66(Hf) furnished an elusive >98% styrene selectivity and full phenylacetylene conversion at room temperature. Such performance is not achievable by a Pd + UiO-66(Hf) physical mixture or by a commercial Pd/C catalyst.
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http://dx.doi.org/10.1039/d0dt00472cDOI Listing
April 2020

Cooperative catalysis at the metal-MOF interface: hydrodeoxygenation of vanillin over Pd nanoparticles covered with a UiO-66(Hf) MOF.

Dalton Trans 2019 Jun 3;48(24):8573-8577. Epub 2019 Jun 3.

Materials Science Division, Poornaprajna Institute of Scientific Research, Devanahalli, Bangalore Rural-562164, India.

Cooperative catalysis has been demonstrated over metal-MOF hybrids for the conversion of vanillin (biomass based platform molecules) into value-added 2-methoxy-4-methylphenol. Over a [email protected](Hf) core-shell catalyst, cooperativity between Brønsted acidic μ-OH groups and Pd active sites present at the interface has rendered a catalytic performance of >99% vanillin conversion and >99% 2-methoxy-4-methylphenol selectivity at 90 °C under 3 bar H in water. An enhanced cooperative effect has been observed over a core-shell catalyst compared to a support catalyst.
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http://dx.doi.org/10.1039/c9dt01371gDOI Listing
June 2019

Metal-Organic Frameworks for Hydrogen Energy Applications: Advances and Challenges.

Chemphyschem 2019 05 24;20(10):1177-1215. Epub 2019 Apr 24.

Materials science division, Poornaprajna Institute of Scientific Research Devanahalli, Bangalore Rural, 576164, India.

Hydrogen is in limelight as an environmental benign alternative to fossil fuels from few decades. To bring the concept of hydrogen economy from academic labs to real world certain challenges need to be addressed in the areas of hydrogen production, storage, and its use in fuel cells. Crystalline metal-organic frameworks (MOFs) with unprecedented surface areas are considered as potential materials for addressing the challenges in each of these three areas. MOFs combine the diverse chemistry of molecular linkers with their ability to coordinate to metal ions and clusters. The unabated flurry of research using MOFs in the context of hydrogen energy related activities in the past decade demonstrates the versatility of this class of materials. In the present review, we discuss major strategical advances that have taken place in the field of "hydrogen economy and MOFs" and point out issues requiring further attention.
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http://dx.doi.org/10.1002/cphc.201801147DOI Listing
May 2019

Exploring the Brønsted acidity of UiO-66 (Zr, Ce, Hf) metal-organic frameworks for efficient solketal synthesis from glycerol acetalization.

Dalton Trans 2019 Jan;48(3):843-847

Materials Science Division, Poornaprajna Institute of Scientific Research, Devanahalli, Bangalore Rural- 562164, India.

Zr, Ce, Hf-based isostructural UIO-66 MOFs exhibited varying degree of Brønsted acidity (UiO-66(Hf) > UiO-66(Ce) > UiO-66(Zr)) on their secondary building units owing to the differences in their oxophilicities. UIO-66(Hf) showed remarkable catalytic activity for solketal synthesis with a turnover frequency as high as 13 886 h-1, which is 90 times higher than that of UiO-66(Zr) and several orders of magnitude higher than that of H2SO4 or Zeolites.
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http://dx.doi.org/10.1039/c8dt03512aDOI Listing
January 2019

An amine functionalized zirconium metal-organic framework as an effective chemiresistive sensor for acidic gases.

Chem Commun (Camb) 2019 Jan;55(3):349-352

Materials Science Division, Poornaprajna Institute of Scientific Research, Bidalur post, Devanahalli, Bengaluru, 562 164, India.

Pore surface functionalization of a metal-organic framework (MOF) with an amine moiety has turned an innocent MOF into a chemiresistive sensor for acidic gases. The Zr-NH2-benzenedicarboxylate MOF (NH2-UiO-66) proved to perform as an efficient and stable chemiresistive sensor for SO2, NO2 and CO2 at low concentrations and an operating temperature of 150 °C.
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http://dx.doi.org/10.1039/c8cc06875eDOI Listing
January 2019

Hybridization of Pd Nanoparticles with UiO-66(Hf) Metal-Organic Framework and the Effect of Nanostructure on the Catalytic Properties.

Chemistry 2018 Oct 5;24(60):15978-15982. Epub 2018 Oct 5.

Materials Science Division, Poornaprajna Institute of Scientific Research, Devanahalli, Bangalore Rural-, 562164, India.

Metal-organic frameworks (MOFs) have emerged as a new class of supports for metal nanoparticles(NPs) in heterogeneous catalysis because of possible synergetic effects between the two components. In addition, MOFs also can be coated over metal NPs to influence the entire nanoparticle's surface. Herein, NPs were hybridized with UiO-66(Hf) MOF possessing Brønsted acidic sites (on secondary building units) and fabricated [email protected] (Hf) core-shell and Pd/UiO-66(Hf) supported catalysts. These hybrid materials exhibited enhanced catalytic properties (TOF increased up to 2.5 times) compared to individual counterparts or their physical mixture for dehydrogenation of ammonia borane(AB) in non-aqueous medium(1,4-dioxane). Further, nanostructure of the hybrid material had pronounced influence on the catalytic properties. The core-shell catalyst exhibited highest activity towards H generation from AB owing to greater contact interface between Pd and MOF. Further, phenylacetylene semi-hydrogenation with AB over [email protected] (Hf) furnished styrene selectivity as high as 93.2 % at ∼100 % conversion mostly due to the regulated phenylacetylene diffusion through UiO-66(Hf) shell.
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http://dx.doi.org/10.1002/chem.201803200DOI Listing
October 2018

Assembly of ZIF-67 Metal-Organic Framework over Tin Oxide Nanoparticles for Synergistic Chemiresistive CO Gas Sensing.

Chemistry 2018 Jul 6;24(37):9220-9223. Epub 2018 Jun 6.

Materials Science Division, Poornaprajna Institute of Scientific Research, Bidalur post, Devanahalli, Bengaluru, India)- 562164.

Metal-organic frameworks (MOFs) are widely known for their record storage capacities of small gas molecules (H , CO , and CH ). Assembly of such porous materials onto well-known chemiresistive gas sensing elements such as SnO could be an attractive prospect to achieve novel sensing properties as this affects the surface chemistry of SnO . Cobalt-imidazole based ZIF-67 MOF was grown onto preformed SnO nanoparticles to realize core-shell like architecture and explored for greenhouse gas CO sensing. CO sensing over SnO is a challenge because its interaction with SnO surface is minimal. The ZIF-67 coating over SnO improved the response of SnO up to 12-fold (for 50 % CO ). The SnO @ZIF-67 also showed a response of 16.5±2.1 % for 5000 ppm CO (threshold limit value (TLV)) at 205 °C, one of the best values reported for a SnO -based sensor. The observed novel CO sensing characteristics are assigned to electronic structure changes at the interface of ZIF-67 and SnO .
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http://dx.doi.org/10.1002/chem.201800847DOI Listing
July 2018

Synergistic Hydrogenation over Palladium through the Assembly of MIL-101(Fe) MOF over Palladium Nanocubes.

Chemistry 2017 Nov 30;23(65):16456-16459. Epub 2017 Oct 30.

Materials science division, Poornaprajna Institute of Scientific Research, Bidalur post, Devanahalli, Bengaluru, 562164, India.

Enhancing catalytic performance of metal nanoparticles is highly sought for many industrial catalytic processes. In this regard, assembly of crystalline porous super-tunable metal-organic frameworks (MOFs) around preformed metal nanoparticles is an attractive prospect as this strongly influences the activity of the entire nanoparticle surface. Herein, we assembled a MlL-101(Fe) MOF onto the Pd nanocubes and evaluated the catalytic properties of the hybrid material for the hydrogenation of the α,β-unsaturated carbonyl compounds cinnamaldehyde, crotonaldehyde, and β-ionone. Owing to the synergestic effects originating from the Lewis acid sites present on MOF and Pd active sites, striking improvements in the activities and selectivities were observed for the Pd⊂MIL-101(Fe) hybrid material. The turnover frequency (TOF) values increased up to roughly 20 fold and in all three studied substrates, C=C was preferentially hydrogenated compared to C=O. Furthermore, the Pd⊂MIL-101(Fe) catalyst was readily reusable and highly stable.
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http://dx.doi.org/10.1002/chem.201704119DOI Listing
November 2017

A cryogenically flexible covalent organic framework for efficient hydrogen isotope separation by quantum sieving.

Angew Chem Int Ed Engl 2013 Dec 11;52(50):13219-22. Epub 2013 Nov 11.

Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany).

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http://dx.doi.org/10.1002/anie.201307443DOI Listing
December 2013

Lewis base mediated efficient synthesis and solvation-like host-guest chemistry of covalent organic framework-1.

Chem Commun (Camb) 2013 Jan;49(5):463-5

Inorganic Chemistry II-Organometallics & Materials Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44780 Bochum, Germany.

N-Lewis base mediated room temperature synthesis of covalent organic frameworks (COFs) starting from a solution of building blocks instead of partially soluble building blocks was developed. This protocol shifts COF synthetic chemistry from sealed tubes to open beakers. Non-conventional inclusion compounds of COF-1 were obtained by vapor phase infiltration of ferrocene and azobenzene, and solvation like effects were established.
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http://dx.doi.org/10.1039/c2cc37183aDOI Listing
January 2013

[email protected]: covalent organic frameworks as templates for Pd nanoparticles and hydrogen storage properties of [email protected] hybrid material.

Chemistry 2012 Aug 8;18(35):10848-56. Epub 2012 Aug 8.

Inorganic Chemistry II-Organometallics & Materials, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany.

Three-dimensional covalent organic frameworks (COFs) have been demonstrated as a new class of templates for nanoparticles. Photodecomposition of the [Pd(η(3)-C(3) H(5))(η(5)-C(5)H(5))]@COF-102 inclusion compound (synthesized by a gas-phase infiltration method) led to the formation of the [email protected] hybrid material. Advanced electron microscopy techniques (including high-angle annular dark-field scanning transmission electron microscopy and electron tomography) along with other conventional characterization techniques unambiguously showed that highly monodisperse Pd nanoparticles ((2.4±0.5) nm) were evenly distributed inside the COF-102 framework. The [email protected] hybrid material is a rare example of a metal-nanoparticle-loaded porous crystalline material with a very narrow size distribution without any larger agglomerates even at high loadings (30 wt %). Two samples with moderate Pd content (3.5 and 9.5 wt %) were used to study the hydrogen storage properties of the metal-decorated COF surface. The uptakes at room temperature from these samples were higher than those of similar systems such as [email protected] frameworks (MOFs). The studies show that the H(2) capacities were enhanced by a factor of 2-3 through Pd impregnation on COF-102 at room temperature and 20 bar. This remarkable enhancement is not just due to Pd hydride formation and can be mainly ascribed to hydrogenation of residual organic compounds, such as bicyclopentadiene. The significantly higher reversible hydrogen storage capacity that comes from decomposed products of the employed organometallic Pd precursor suggests that this discovery may be relevant to the discussion of the spillover phenomenon in metal/MOFs and related systems.
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http://dx.doi.org/10.1002/chem.201201340DOI Listing
August 2012

Preparation, microstructure characterization and catalytic performance of Cu/ZnO and ZnO/Cu composite nanoparticles for liquid phase methanol synthesis.

Phys Chem Chem Phys 2012 Jun 1;14(22):8170-8. Epub 2012 May 1.

Lehrstuhl für Anorganische Chemie II, Ruhr Universität Bochum, Universitätstrasse 150, 44780 Bochum, Germany.

[email protected]/ZnO nanocomposite particles with molar ratios of ZnO ∶ Cu = 2 and 5 are synthesized by reduction of the metal-organic Cu precursor [Cu{(OCH(CH(3))CH(2)N(CH(3))(2))}(2)] in the presence of [email protected] nanoparticles. In the case of ZnO ∶ Cu = 5, high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) combined with electron-energy-loss-spectroscopy (EELS) as well as attenuated total reflection Fourier transform infrared (ATR-IR) spectroscopy are used to localize the small amount of Cu deposited on the surface of 3-5 nm sized [email protected] particles. For ZnO ∶ Cu = 2, the microstructure of the nanocomposites after catalytic activity testing is characterized by HAADF-STEM techniques. This reveals the construction of large Cu nanoparticles (20-50 nm) decorated by small ZnO nanoparticles (3-5 nm). The catalytic activity of both composites for the synthesis of methanol from syn gas is evaluated.
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http://dx.doi.org/10.1039/c2cp40482fDOI Listing
June 2012

Nanocatalysis and prospects of green chemistry.

ChemSusChem 2012 Jan 20;5(1):65-75. Epub 2011 Dec 20.

Department of Inorganic and Physical Chemistry, Indian Institute of Science (IISc), Bangalore, India.

Designing and developing ideal catalyst paves the way to green chemistry. The fields of catalysis and nanoscience have been inextricably linked to each other for a long time. Thanks to the recent advances in characterization techniques, the old technology has been revisited with a new scope. The last decade has witnessed a flood of research activity in the field of nanocatalysis, with most of the studies focusing on the effect of size on catalytic properties. This led to the development of much greener catalysts with higher activity, selectivity and greater ease of separation from the reaction medium. This Minireview describes the emerging trends in the field of nanocatalysis with implications towards green chemistry and sustainability.
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http://dx.doi.org/10.1002/cssc.201100377DOI Listing
January 2012

[email protected]: selective formation of gallium nitride quantum dots inside a zinc methylimidazolate framework.

J Am Chem Soc 2011 Oct 26;133(41):16370-3. Epub 2011 Sep 26.

Department of Inorganic Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany.

The microporous zeolitic imidazolate framework [Zn(MeIM)(2); ZIF-8; MeIM = imidazolate-2-methyl] was quantitatively loaded with trimethylamine gallane [(CH(3))(3)NGaH(3)]. The obtained inclusion compound [(CH(3))(3)NGaH(3)]@ZIF-8 reveals three precursor molecules per host cavity. Treatment with ammonia selectively yields the caged cyclotrigallazane intermediate (H(2)GaNH(2))(3)@ZIF-8, and further annealing gives [email protected] This new composite material was characterized with FT-IR spectroscopy, solid-state NMR spectroscopy, powder X-ray diffraction, elemental analysis, (scanning) transmission electron microscopy combined with electron energy-loss spectroscopy, photoluminescence (PL) spectroscopy, and N(2) sorption measurements. The data give evidence for the presence of GaN nanoparticles (1-3 nm) embedded in the cavities of ZIF-8, including a blue-shift of the PL emission band caused by the quantum size effect.
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http://dx.doi.org/10.1021/ja207077uDOI Listing
October 2011

B-N [email protected]: dehydrocoupling of dimethylamine borane at room temperature by size-confinement effects.

Chemistry 2011 Jun 26;17(24):6594-7. Epub 2011 Apr 26.

Inorganic Chemistry II, Ruhr University, Bochum, Germany.

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http://dx.doi.org/10.1002/chem.201100518DOI Listing
June 2011

[email protected]: organometallic host-guest chemistry of porous crystalline organic frameworks.

Chem Commun (Camb) 2011 Aug 18;47(30):8506-8. Epub 2011 Apr 18.

Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstrasse 150, 44801 Bochum, Germany.

The organometallic host-guest chemistry of porous covalent organic frameworks is explored by vapour phase infiltration of volatile organometallic precursors; namely, [Fe(η(5)-C(5)H(5))(2)], [Co(η(5)-C(5)H(5))(2)], and [Ru(cod)(cot)]. The unique arrangement of ferrocene molecules inside COF-102 is driven by π-π (host-guest) interactions and replicates the framework symmetry.
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http://dx.doi.org/10.1039/c1cc11450fDOI Listing
August 2011

Chemical synthesis of metal nanoparticles using amine-boranes.

ChemSusChem 2011 Mar 18;4(3):317-24. Epub 2011 Jan 18.

Department of Inorganic & Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India.

The development of new synthetic strategies to obtain monodisperse metal nanoparticles on large scales is an attractive prospect in the context of sustainability. Recently, amine-boranes, the classical Lewis acid-base adducts, have been employed as reducing agents for the synthesis of metal nanoparticles. They offer several advantages over the traditional reducing agents like the borohydrides; for example, a much better control of the rate of reduction and, hence, the particle size distribution of metal nanoparticles; diversity in their reducing abilities by varying the substituents on the nitrogen atom; and solubility in various protic and aprotic solvents. Amine-boranes have not only been used successfully as reducing agents in solution but also in solventless conditions, in which along with the reduction of the metal precursor, they undergo in situ transformation to afford the stabilizing agent for the generated metal nanoparticles, thereby bringing about atom economy as well. The use of amine boranes for the synthesis of metal nanoparticles has experienced an explosive growth in a very short period of time. In this Minireview, recent progress on the use of amine boranes for the synthesis of metal nanoparticles, with a focus towards the development of pathways for sustainability, is discussed.
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http://dx.doi.org/10.1002/cssc.201000318DOI Listing
March 2011

Metal nanoparticles via the atom-economy green approach.

Inorg Chem 2010 May;49(9):3965-7

Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

Metal nanoparticles (NPs) of Cu (air-stable), Ag, and Au have been prepared using an atom-economy green approach. Simple mechanical stirring of solid mixtures (no solvent) of a metal salt and ammonia borane at 60 degrees C resulted in the formation of metal NPs. In this reaction, ammonia borane is transformed into a BNH(x) polymer, which protects the NPs formed and halts their growth. This results in the formation of the BNH(x) polymer protected monodisperse NPs. Thus, ammonia borane used in these reactions plays a dual role (reducing agent and precursor for the stabilizing agent).
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http://dx.doi.org/10.1021/ic100431kDOI Listing
May 2010

Highly monodisperse colloidal magnesium nanoparticles by room temperature digestive ripening.

Inorg Chem 2009 May;48(10):4524-9

Department of Inorganic & Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

Nanoclusters of 25 nm sized Mg-THF have been prepared by the solvated metal atom dispersion method. Room-temperature digestive ripening of these nanoclusters in the presence of hexadecylamine (HDA) resulted in highly monodisperse colloidal Mg-HDA nanoparticles of 2.8 +/- 0.2 nm. An insight into the room-temperature digestive ripening process was obtained by studying the disintegration of clusters for various Mg:HDA ratios. The Mg colloids are quite stable with respect to precipitation of particles under Ar atmosphere. Using this procedure, pure Mg(0) nanopowders were obtained in gram scale quantities. The Mg powder precipitated from the colloid was fully hydrided at 33 bar and 118 degrees C. Initial desorption of H(2) from samples of MgH(2) was achieved at a remarkably low temperature, 115 degrees C compared to >350 degrees C in bulk Mg, demonstrating the importance of the size on the desorption temperatures.
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http://dx.doi.org/10.1021/ic9003577DOI Listing
May 2009

Magnesium/copper nanocomposite through digestive ripening.

Chem Asian J 2009 Jun;4(6):835-8

Department of Inorganic & Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

Composing nanocomposites: Co-digestive ripening of as-prepared Mg and Cu colloids prepared by the solvated metal atom dispersion method results in a highly monodisperse colloid of Mg/Cu nanocomposite with an average particle size of 3.0+/-0.5 nm. Annealing of these samples at 300 degrees C gives the Cu/MgO nanocomposite.
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http://dx.doi.org/10.1002/asia.200800447DOI Listing
June 2009

Co-Co2B, Ni-Ni3B and Co-Ni-B nanocomposites catalyzed ammonia-borane methanolysis for hydrogen generation.

Phys Chem Chem Phys 2009 Feb 28;11(5):770-5. Epub 2008 Nov 28.

Department of Inorganic & Physical Chemistry, Indian Institute of Science, Bangalore, 560 012, India.

Co-Co(2)B and Ni-Ni(3)B nanocomposites were synthesized by the reduction of Co(2+) and Ni(2+) ions using ammonia-borane in methanol. The Co-Ni-B nanocomposite was synthesized by the co-reduction of Co(2+) and Ni(2+) ions. The catalytic activities of these metal nanocomposites were studied for the dehydrogenation of ammonia-borane in methanol. Three moles of H(2) were liberated in 2.5 min and 4.2 min in case of Co-Co(2)B and Ni-Ni(3)B nanocomposites, respectively (catalyst/AB = 0.2). The Co-Ni-B nanocomposite showed greater activity compared to individual metal-metal boride nanocomposites: 3 moles of H(2) were liberated in 1.5 min (catalyst/AB = 0.2). The catalysts were highly recyclable and the activities remained almost unchanged even after several cycles.
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http://dx.doi.org/10.1039/b814216eDOI Listing
February 2009

Nanostructured Cu and [email protected](2)O core shell catalysts for hydrogen generation from ammonia-borane.

Phys Chem Chem Phys 2008 Oct 11;10(38):5870-4. Epub 2008 Aug 11.

Department of Inorganic & Physical Chemistry, Indian Institute of Science, Bangalore, India.

Copper nanoparticles have been prepared by the solvated metal atom dispersion (SMAD) method. Oxidation of the SMAD prepared copper colloids resulted in [email protected](2)O core shell structures (7.7 +/- 1.8 nm) or Cu(2)O nanoparticles depending on the reaction conditions. The nano Cu, [email protected](2)O core shell, and Cu(2)O particles were found to be catalytically active for the generation of hydrogen from ammonia-borane either via hydrolysis or methanolysis reaction.
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http://dx.doi.org/10.1039/b805726eDOI Listing
October 2008

First row transition metal ion-assisted ammonia-borane hydrolysis for hydrogen generation.

Inorg Chem 2008 Aug 23;47(16):7424-9. Epub 2008 Jul 23.

Department of Inorganic & Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

Ammonia-borane (AB) hydrolysis for the generation of hydrogen has been studied using first row transition metal ions, such as Co (2+), Ni (2+), and Cu (2+). In the cases of cobalt- and nickel-assisted AB hydrolysis, amorphous powders are formed that are highly catalytically active for hydrogen generation. Annealing of these amorphous powders followed by powder X-ray diffraction measurements revealed the presence of Co(0) and Co 2B and Ni(0) and Ni 3B, respectively. On the other hand, copper-assisted AB hydrolysis was catalyzed by in situ generated H (+) and Cu(0) nanoparticles. The reduction ability of AB for the realization of coinage metal nanoparticles from the respective metal salts has also been studied. These reduction reactions were found to be facile, affording colloids of pure metal nanoparticles. Nanoparticles prepared in this manner were characterized by UV-visible spectroscopy and high-resolution electron microscopy.
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http://dx.doi.org/10.1021/ic800805rDOI Listing
August 2008
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