@article { ISI:000267381100014, title = {Synthesis of catalytically active porous platinum nanoparticles by transmetallation reaction and proposition of the mechanism}, journal = {Small}, volume = {5}, number = {12}, year = {2009}, month = {JUN}, pages = {1467-1473}, publisher = {WILEY-V C H VERLAG GMBH}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

A facile method for the synthesis of porous platinum nanoparticles by transmetallation reactions between sacrificial nickel nanoparticles and chloroplatinic acid (H(2)PtCl(6)) in solution, as well as at the constrained environment of the air water interface, using a Langmuir-Blodgett instrumental setup is presented. To carry out the transmetallation at the air-water interface hydrophobized nickel nanoparticles are assembled as a monolayer on the sub phase containing platinum ions. The porous Pt nanoparticles obtained as a result of the reaction are found to act as extremely good catalysts for hydrogenation reaction. The products are well characterized by TEM, HRTEM, EDAX, and STEM. Attempts are made to postulate the plausible mechanism of this reaction to generate this kind of nanoparticle with controllable geometric shape and structure. This simple strategy has the potential to synthesize other nanomaterials of interest too.

}, keywords = {Catalysts, Interfaces, Nickel nanoparticles, porous platinum, Transmetallation}, issn = {1613-6810}, doi = {10.1002/smll.200801863}, author = {Pasricha, Renu and Bala, Tanushree and Biradar, Ankush V. and Shubhangi B. Umbarkar and Sastry, Murali} } @article { ISI:000288529500015, title = {Role of lattice defects and crystallite morphology in the UV and visible-light-induced photo-catalytic properties of combustion-prepared TiO2}, journal = {Materials Chemistry and Physics}, volume = {126}, number = {3}, year = {2011}, month = {APR}, pages = {546-554}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The physico-chemical, photo-physical and micro-structural properties responsible for the strikingly different photocatalytic behavior of combustion-prepared TiO2 (c.TiO2) and Degussa P25 (d.TiO2) samples are elucidated in this study. Electron microscopy and selected area electron diffraction micrographs revealed that the two samples exhibited different morphologies. The grains of c.TiO2 were spherical and comprised of 5-6 nm size primary particle. On the other hand, d.TiO2 consisted of large (0.5-3.0 mu m) size and irregular shape aggregates having primary particles of 15-40 nm cross-sectional diameter. The ESR study revealed that the presence of certain defect states in c.TiO2 helped in stabilization of O-. and Ti3+-OH type species during room-temperature UV-irradiation. No such paramagnetic species were however formed over d.TiO2 under similar conditions. C1s and Ti 2p XPS spectra provide evidence for the presence of some lattice vacancies in c.TiO2 and also for the bulk Ti4+ -\> Ti3+ conversion during its UV-irradiation. Compared to d.TiO2, c.TiO2 displayed considerably higher activity for discoloration of methyl orange but very poor activity for splitting of water, both under UV and visible light radiations. This is attributed to enhanced surface adsorption of dye molecules over c.TiO2, because of its textural features and also the presence of photo-active ion-radicals. On the other hand, the poor activity of c.TiO2 for water splitting is related to certain defect-induced inter-band charge trapping states in the close vicinity of valence and conduction bands of c.TiO2, as revealed by thermoluminescence spectroscopy. Further, the dispersion of nanosize gold particles gave rise to augmented activity of both the catalysts, particularly for water splitting. This is explained by the promotional role of Au-0 or Au-0/TiO2 interfacial sites in the adsorption and charge-adsorbate interaction processes. (C) 2011 Elsevier B.V. All rights reserved.

}, keywords = {Band-structure, Interfaces, Microstructure, Nanostructures, Semiconductors}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2011.01.029}, author = {Deshpande, Aparna and Madras, Giridhar and Gupta, N. M.} } @article { ISI:000303485400020, title = {Effects of grain morphology, microstructure and dispersed metal cocatalyst on the photoreduction of water over impurity-doped LaInO3}, journal = {Materials Research Bulletin}, volume = {47}, number = {5}, year = {2012}, month = {MAY}, pages = {1217-1228}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

The single phase lanthanum indates doped with Ga (for La) and N (for O), i.e. La1-xGaxInO3 (0 \<= x \<= 0.2) and LaInO1-yNy (y similar to 0.6), exhibit significant activity for photoreduction of water; the yield of H-2 produced depending on dopant, excitation source, and addition of a sacrificial reagent. The two-step H-2 evolution observed for this reaction corresponds with the two distinct absorbance regimes displayed by these materials, one in UV-region due to bandgap excitation and the other in visible region arising from the transitions involving sub-bandgap donor or acceptor energy states. The photocatalytic activity of these d(10) metal oxides increases on coating with a metal/metal oxide co-catalyst, gold exhibiting superior activity to Pt and NiO, irrespective of excitation source and sample composition. The preparation-controlled particle morphology, doping-induced lattice imperfections, and metal/semiconductor hetero-junctions are envisaged to play a key role in the absorption characteristics and photocatalytic water reduction activity of metal/LaInO3 nanocomposites. (C) 2012 Elsevier Ltd. All rights reserved.

}, keywords = {Catalytic properties, Chemical synthesis, Electron microscopy, Interfaces, Semiconductors}, issn = {0025-5408}, doi = {10.1016/j.materresbull.2012.01.031}, author = {Dhanasekaran, P. and Gupta, N. M.} } @article { ISI:000381182700004, title = {Spectacular rate enhancement of the diels-alder reaction at the ionic liquid/n-hexane interface}, journal = {Chemphyschem}, volume = {17}, number = {13}, year = {2016}, month = {JUL}, pages = {1969-1972}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

The use of the ionic liquid/n-hexane interface as a new class of reaction medium for the Diels-Alder reaction gives large rate enhancements of the order of 10(6) to 10(8) times and high stereoselectivity, as compared to homogeneous media. The rate enhancement is attributed to the H-bonding abilities and polarities of the ionic liquids, whereas the hydrophobicity of ionic liquids was considered to be the factor in controlling stereoselectivity.

}, keywords = {Diels-Alder reaction, Interfaces, ionic liquids, kinetics, stereoselectivity}, issn = {1439-4235}, doi = {10.1002/cphc.201600006}, author = {Beniwal, Vijay and Manna, Arpan and Kumar, Anil} }