ORCID Profile
0000-0003-2307-1920
Current Organisation
Indian Institute of Chemical Technology
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Publisher: Elsevier BV
Date: 09-2008
Publisher: Trans Tech Publications Ltd.
Date: 15-01-2007
Publisher: American Scientific Publishers
Date: 09-2007
DOI: 10.1166/JNN.2007.919
Abstract: Carbon nanocage, a three dimensional cage type mesoporous carbon with very high surface area and pore volume, has been functionalized with carboxyl groups for the first time via a simple oxidation using ammonium persulfate solution (APS). The carboxyl groups functionalized carbon nanocage materials have been unambiguously characterized by various sophisticated instruments such as FT-IR, HRSEM-EDX, XRD, nitrogen adsorption, and HRTEM. The degree of carboxyl group functionalization has been controlled by the simple adjustment of the oxidation parameters such as oxidation time, APS concentration and oxidation temperature. FT-IR spectroscopy combined with the HRSEM-EDX has been used to provide a quantitative analysis of the carboxyl groups on the surface of the carbon nanocage materials before and after the APS treatment. In addition, the effect of the oxidation parameters on the structural order and the textural parameters of the carbon nanocage materials has been studied. It has been found that the role of oxidation parameters is highly critical to obtain carbon nanocage materials with a high density of carboxyl groups without affecting the structural order and the pore parameters. Thus, the reaction parameters have been carefully optimized and the best condition for the preparation of carboxyl group functionalized carbon nanocage with well-ordered structure has been proposed.
Publisher: Elsevier BV
Date: 03-2007
Publisher: Elsevier BV
Date: 06-2013
Publisher: American Scientific Publishers
Date: 2009
Abstract: Nanocrystalline HoCrO4 powder was synthesized by a combustion technique using glycine and citric acid as the fuels in different oxidant-to-fuel ratios. Fuel-deficient glycine-nitrate combustion reaction resulted in zircon type HoCrO4 free from HoCrO3 phase. The crystallite size for the phase pure product after calcination at 575 degrees C in oxygen atmosphere was found to be 34 nm by X-ray line broadening. The TEM observations showed highly porous structure. Magnetic measurements reveal the ferromagnetic nature of HoCrO4 nano particles with Tc = 18 K. The compound shows high remanence of 30.4 emu x g(-1) and low coercivity of -0.0343 T.
Publisher: Elsevier BV
Date: 02-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC12378E
Abstract: We report a new synthetic route for preparation of nanoporous carbon nitride fibers with graphitic carbon nitride polymers, by calcination of Al-based porous coordination polymers (Al-PCPs) with dicyandiamide (DCDA) under a nitrogen atmosphere.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CP03216K
Abstract: Ordered mesoporous ferrosilicate materials with highly dispersed iron oxide nanoparticles are directly synthesized through a hydrothermal approach under acidic conditions.
Publisher: The Chemical Society of Japan
Date: 05-10-2008
DOI: 10.1246/CL.2008.1016
Publisher: Elsevier BV
Date: 03-2008
Publisher: American Scientific Publishers
Date: 08-2009
Abstract: A facile, fast, and economic method of doping TiO2, synthesized by conventional precipitation route with N has been developed. By this method, stable N doped TiO2 can be prepared within a short duration of time. The method adopted was to treat the TiO2 powder synthesized by simple precipitation with trioctyl amine (TOA) at 320 degrees C for 2 hours followed by calcination at 400 degrees C for 2 hours to obtain the N-doped TiO2. The s le along with NiO as co-catalyst showed significant photocatalytic activity for hydrogen generation from aqueous methanol solution under sunlight type irradiation. This synthesis method opens up a fast and easy route for doping the existing TiO2 or other wide band gap oxide semiconductors with nitrogen so that they can exhibit enhanced photocatalytic activity under solar irradiation.
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B613899C
Publisher: American Chemical Society (ACS)
Date: 03-04-2008
DOI: 10.1021/JP800576Y
Publisher: American Scientific Publishers
Date: 02-05-2009
DOI: 10.1166/JNN.2009.026
Abstract: Eu3+ and Dy3+ doped YPO4 nanoparticles dispersible in methanol/water were prepared by the reaction of Y3+ and Eu3+/Dy3+ ions with ammonium dihydrogen phosphate in ethylene glycol medium at 160 degrees C. Nature and extent of strain associated with lattice has been found to change with incorporation of Eu3+/Dy3+ ion in the nanoparticles as well as the heat treatment temperature. Based on the TEM studies, it has been established that particles are highly crystalline with an average particle size of around 5 nm. Co-doping YPO4:Eu nanoparticles with Dy3+ ions followed by annealing them at high temperature (900 degrees C) lead to reduction in both Eu3+ and Dy3+ luminescence intensities from the s le and this has been attributed to the clustering effect of the lanthanide ions.
Publisher: American Scientific Publishers
Date: 08-2007
DOI: 10.1166/JNN.2007.631
Abstract: Novel flower like microporous carbons with very high surface area have been synthesized for the first time using MCM-22 zeolite as a template and sucrose as a carbon source. The textural parameters of the materials can easily be tuned by the simple adjustment of the sucrose to MCM-22 weight ratio. It has been also found that the specific surface area of the microporous carbon materials is much higher as compared with that of its parent zeolite template.
Publisher: Wiley
Date: 12-10-2009
Publisher: Trans Tech Publications, Ltd.
Date: 2007
DOI: 10.4028/WWW.SCIENTIFIC.NET/SSP.119.291
Abstract: Mesoporous carbon nitride materials have been synthesized using SBA-15 by pore filling technique whereas mesoporous boron nitride and boron carbon nitride have been prepared by elemental substitution technique using mesoporous carbon as template. The obtained materials have been unambiguously characterized by sophisticated techniques such as XRD, HRTEM, EELS, XPS, FT-IR and N2 adsorption. The textural parameters of the materials are quite higher as compared to the respective nonporous nitrides. These materials could offer great potential for the applications, such as catalytic supports, gas storage, biomolecule adsorption and drug delivery.
Publisher: Elsevier BV
Date: 10-2008
Publisher: Wiley
Date: 05-02-2015
Publisher: Elsevier BV
Date: 09-2012
Publisher: Wiley
Date: 18-03-2008
Abstract: The preparation of SBA-15/TiO(2) nanocomposites with different loadings of Keggin-type 12-tungstophosphoric acid (TPA) nanocrystals in their mesochannels through a simple and effective vacuum impregnation method is reported for the first time. The catalysts have been characterised by various sophisticated techniques, including XRD, HRSEM, and TEM. It has been found that the acidity and the textural parameters of the nanocomposites can be controlled by simply changing the loadings of TPA and TiO(2) or the calcination temperature. TPA and TiO(2) loadings of 15 and 22.4 wt %, respectively, and a calcination temperature of 1123 K have proved to be optimal for obtaining mesoporous nanocomposite materials with the highest acidity. Moreover, the activities of these catalysts in promoting hydroamination as well as Mannich and Claisen rearrangement reactions have been extensively investigated. The results show that the amount of TPA has a great influence on the activity of the nanocomposites in all of the reactions studied. The effects of other reaction parameters, such as temperature and reaction time, on the conversion and product selectivity have also been studied in detail. A kinetic analysis of the formation of the products under various reaction conditions is presented. It has been found that the activity of the nanocomposite composed of 15 wt % TPA deposited on 22.4 wt of TiO(2) on SBA-15 in promoting the studied reaction is remarkably higher than the catalytic activities shown by pure TPA, TiO(2)-loaded SBA-15, or TPA-loaded SBA-15. The results obtained have indicated that the acidity and the structural control of the nanocomposite materials are highly critical for obtaining excellent catalytic activity, and the presented highly acidic nanocomposites are considered to show great potential for use as catalysts in promoting many acid-catalysed organic transformations.
Publisher: American Chemical Society (ACS)
Date: 02-2012
DOI: 10.1021/JA208940U
Abstract: Nanoporous carbon (NPC) is prepared by direct carbonization of Al-based porous coordination polymers (Al-PCP). By applying the appropriate carbonization temperature, both high surface area and large pore volume are realized for the first time. Our NPC shows much higher porosity than other carbon materials (such as activated carbons and mesoporous carbons). This new type of carbon material exhibits superior sensing capabilities toward toxic aromatic substances.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 1983
Publisher: Elsevier BV
Date: 03-2007
Publisher: Elsevier BV
Date: 05-2009
Publisher: Elsevier BV
Date: 04-2008
Publisher: American Chemical Society (ACS)
Date: 03-06-2008
DOI: 10.1021/JP800292A
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM33498D
Publisher: American Chemical Society (ACS)
Date: 25-05-2006
DOI: 10.1021/JP061523H
Abstract: Iron substituted cubic cage type mesoporous molecular sieves (FeSBA-1) were synthesized for the first time in a highly acidic media using cetyltriethylammonium bromide as a template. The amount of Fe incorporation in SBA-1 can easily be controlled by the simple adjustment of the molar hydrochloric acid-to-silicon ratio. All the materials were unambiguously characterized by AAS, XRD, N2 adsorption, UV-Vis DRS, XPS, and ESR spectroscopy. The results from AAS, XRD, and N2 adsorption reveal that the iron atom can be incorporated in the framework of SBA-1 matrix without altering the structural order and the textural parameters. The nature and the coordination of iron atoms were extensively studied by XPS spectroscopy, and the results revealed that most of the iron atoms in FeSBA-1 are in +3 coordination state. UV-Vis DRS and ESR studies confirmed that the majority of the Fe atoms in FeSBA-1 exist in a tetrahedral coordination environment (most probably occupying framework positions). tert-Butylation of phenol employing tert-butanol as the alkylation agent was carried out over FeSBA-1 catalysts with different iron content and the results are compared with one-dimensional mesoporous catalysts. The influence of various reaction parameters such as reaction temperature, reactant feed ratio, weight hourly space velocity, and time-on-stream affecting the activity and selectivity of FeSBA-1 were also studied. Under the optimized reaction conditions, the FeSBA-1(36) catalyst showed superior catalytic performance for the tert-butylation of phenol as compared to the uni-dimensional mesoporous catalysts.
Publisher: American Chemical Society (ACS)
Date: 16-12-2005
DOI: 10.1021/JP055851D
Abstract: Highly ordered TiSBA-15 mesoporous molecular sieves with different nSi/nTi ratios and tunable pore diameters have been prepared through direct synthesis under various hydrochloric acid concentrations and synthetic temperatures. The structure and the textural parameters of the materials were investigated by powder X-ray diffraction and nitrogen adsorption/desorption measurements. Decrease of the acid concentration and nSi/nTi ratio in the synthetic gel enhanced the amount of Ti incorporation in SBA-15 materials without affecting their structural order and textural parameters. Highly ordered mesoporous TiSBA-15 with a very high Ti content up to a nSi/nTi ratio of 1.9 was prepared for the first time under the optimized synthesis conditions. Control of synthetic temperature resulted in tuning of pore geometries without structural deterioration and Ti content. Ultralarge-pore TiSBA-15 with a pore size of 12.6 nm and a pore volume of 1.3 cm3 g-1 was also synthesized. The nature and the coordination of the Ti atoms in SBA-15 prepared under various synthesis conditions were investigated by UV-vis spectroscopy. It has been found that the Ti atoms are well-dispersed and mostly occupy the tetrahedral coordination under the optimized synthesis conditions. Catalytic performance of the obtained TiSBA-15 materials was also investigated through oxidation of styrene by hydrogen peroxide and tert-butylhydroperoxide as oxidants.
Publisher: American Scientific Publishers
Date: 2010
Abstract: Here we demonstrate for the first time the fabrication hexagonally ordered mesoporous carbon materials with different morphology and pore diameters using NbSBA-15 mesoporous silica template with different niobium content. The materials were characterized by several characterization techniques such as XRD, HRSEM, HRTEM, elemental mapping, ICP-AES, and EDS analysis. We also demonstrate that the morphology of the materials can be controlled by simply tuning the morphology of the parent NbSBA-15 template, whose morphology can be tuned by adjusting the loading of niobium in the framework wall structure of SBA-15. Nitrogen adsorption results reveal that the textural parameters of the mesoporous carbon materials prepared from NbSBA-15 are much better than those prepared with pristine SBA-15 template, and vary with the amount niobium present in the template. It was also found that the pore diameter of the NbMC-X increases with decreasing the amount of niobium in the framework wall structure of the template. The morphology and the topology of the materials were observed by HRSEM and HRTEM, respectively. The materials with rod and semi-spherical or winding road like morphology can be obtained using NbSBA-15 materials with different Nb content. It was found that the usage of NbSBA-15 as templates for the fabrication of mesoporous carbon materials can also allow us to decorate the pore channels of the materials with either niobium oxide or niobium silicate nanoparticles which are expected to show high performance when used in redox catalysis, and the biomolecule adsorption as the niobium has the strong tendency to adsorb the protein molecules.
Publisher: American Chemical Society (ACS)
Date: 16-12-2014
DOI: 10.1021/IE503576D
Publisher: Elsevier BV
Date: 04-2008
Publisher: Elsevier BV
Date: 02-2013
Publisher: Elsevier BV
Date: 12-2008
Publisher: American Chemical Society (ACS)
Date: 28-07-2007
DOI: 10.1021/CM070657K
Publisher: Elsevier BV
Date: 09-2007
Publisher: Wiley
Date: 22-02-2008
Publisher: American Chemical Society (ACS)
Date: 07-07-2015
Publisher: The Chemical Society of Japan
Date: 05-06-2007
DOI: 10.1246/CL.2007.770
Publisher: Wiley
Date: 09-04-2008
Abstract: Three-dimensional, mesoporous-cage-type, GaSBA-1 materials with different n(Si)/n(Ga) ratios have been successfully prepared for the first time by using a low hydrochloric acid to silicon (n(HCl)/n(Si)) molar ratio in the synthesis gel by templating with cetyltriethylammonium bromide as the structure-directing agent in a highly acidic medium. The obtained materials have been unambiguously characterized in detail by several sophisticated techniques including X-ray diffraction (XRD), N(2) adsorption, high-resolution transmission electron microscopy, high-resolution scanning electron microscopy, energy dispersive spectroscopy, elemental mapping, and (29)Si magic-angle-spinning NMR spectroscopy. XRD and nitrogen adsorption results reveal that the structures of the GaSBA-1 materials resemble that of SBA-1, which possesses a cubic, three-dimensional, cage-type structure with open windows. In addition, the specific surface area and the specific pore volume of the GaSBA-1 materials are much higher than those of the SBA-1 silica, which are very important for the catalytic applications. The amount of Ga cation in the SBA-1 silica framework has been found to play a critical role in controlling the morphology and the pore diameter of the materials. Finally, the catalytic activity in the tert-butylation of phenol with tert-butanol as the alkylating agent has been investigated and the results are compared with those of other mesoporous catalysts such as AlMCM-41, FeMCM-41, FeAl-MCM-41, and FeSBA-1. Moreover, the effect of various reaction parameters such as the reaction temperature, reactant feed ratio, and time-on-stream on the phenol conversion in the tert-butylation of phenol over GaSBA-1 catalysts has been demonstrated. Among the catalysts examined, GaSBA-1(17), in which the number in the parenthesis denotes the n(Si)/n(Ga) ratio, showed remarkable activity with a high conversion of phenol and selectivity to 4-tert-butylphenol it was found to be superior over other mesoporous catalysts used in the study.
Publisher: Elsevier BV
Date: 10-2007
Publisher: Elsevier BV
Date: 04-2007
No related grants have been discovered for SRINIVASU PAVULURI.