@article { ISI:000227196900007, title = {Characterization of nanocrystalline anatase titania: an in situ HTXRD study}, journal = {Thermochimica Acta}, volume = {427}, number = {1-2}, year = {2005}, month = {MAR}, pages = {37-41}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Nanocrystalline titania was synthesized by the hydrolysis of titanium iso-propoxide using ultrasonication. The powder XRD patterns of the sample were recorded in static air and vacuum using a Philips X-pert Pro diffractometer equipped with a high-temperature attachment (HTK16) from room temperature (298 K) to 1173 K and were analyzed by the Rietveld refinement technique. The anatase to rutile phase transformation was observed at 1173 K for the data collected in static air. Only 3\% of anatase titania transformed to rutile when the experiments were carried out at H 73 K in vacuum. The phase transformation from anatase to rutile is accompanied by a continuous increase in the crystallite size of the anatase phase from 9 nm at room temperature to 28 nm at 873 K and then to 50 nm at 1173 K in air while the process of crystallite growth was suppressed in vacuum. A linear increase in the unit cell parameters {\textquoteleft}a{\textquoteright} and {\textquoteleft}c{\textquoteright}, and thus, an overall linear increase in the unit cell volume was observed as a function of temperature in static air as well as vacuum. The lattice and volume thermal expansion coefficients (TEC), alpha(a), alpha(c), and alpha(v) at 873 K are 8.57 x 10(-6), 8.71 x 10(-6) and 25.91 x 10(-6) K-1 in air and 18.01 x 10(-6), 14.95 x 10(-6) and 51.13 x 10(-6) K-1 in vacuum, respectively. (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {Anatase, HTXRD, Rietveld refinement, rutile, thermal expansion coefficient, titania}, issn = {0040-6031}, doi = {10.1016/j.tca.2004.08.011}, author = {Jagtap, Neelam and Bhagwat, Mahesh and Awati, Preeti and Ramaswamy, Veda} } @article { ISI:000240365800049, title = {Heteropoly acid supported on titania as solid acid catalyst in alkylation of p-cresol with tert-butanol}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {256}, number = {1-2}, year = {2006}, month = {AUG}, pages = {324-334}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Butylation of p-cresol with tert-butanol was investigated on titania modified with 12-tungstophosphoric acid (TPA/TiO2) catalyst under vapor phase conditions. Catalysts with different TPA loadings (10-25 wt.\%) and calcination temperatures (650-750 degrees C) were prepared by suspending titanium hydroxide in methanol solution of TPA followed by drying and calcination. These catalysts were characterized by surface area, XRD, P-31 MAS NMR, XPS, NH3-TPD, and FTIR pyridine adsorption. XRD results indicated that the presence of TPA retarded the crystallization of titania and stabilized TiO2 in anatase phase. P-31 MAS NMR indicated the presence of TPA in various forms (dispersed, highly fragmented and Keggin intact). These catalysts showed both Bronsted and Lewis acidity, and 20\% TPA on TiO2 calcined at 700 degrees C (from here after words 20\% TT 700) had the highest Bronsted as well as total acidity. Further, the catalytic activities were examined in tert-butylation of p-cresol with tent-butanol. The catalytic activity depended on TPA coverage, and the highest activity corresponded to the monolayer of TPA on titania. The most active catalyst 20\% TT-700 gave 82\% conversion of p-cresol and 89.5\% selectivity towards 2-tert-butyl cresol (TBC), 2,6-di-tert-butyl cresol (DTBC) 7.5\% and cresol-tert-butyl ether (CTBE) 3\% under optimized conditions. The activity was always higher than that of WO3/ZrO2, sulfated zirconia (SZ), USY, H-beta zeolites and montmorillonite K-10 (K-10mont) under similar conditions. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {2, 2-tert-butyl-p-cresol, 6-di-tert-butyl-p-cresol, Alkylation, heteropoly acid, p-Cresol, tert-butanol, titania}, issn = {1381-1169}, doi = {10.1016/j.molcata.2006.05.024}, author = {Kumbar, Suresh M. and Shanbhag, G. V. and Lefebvre, F. and Halligudi, Shivaraj B.} } @article { ISI:000236922600002, title = {Room temperature synthesis of mesoporous aggregates of anatase TiO2 nanoparticles}, journal = {Materials Chemistry and Physics}, volume = {97}, number = {2-3}, year = {2006}, month = {JUN}, pages = {207-212}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The controlled hydrolysis reaction of titanium tetrabutoxide in presence of acetic acid in isopropanol, i.e. in non-aqueous media was adopted in the present work for the synthesis of nanocrystalline titania followed by aging at ambient conditions for longer duration. The powder XRD shows that the as-dried precursor (without any aging) is non-crystalline in nature. However, room temperature aging for longer duration \> 120 days not only helped to develop crystallinity in TiO2 nanoparticles but also led to the formation of their self-assembly towards mesoporous aggregates creating sponge like TiO2 nano-structure having high surface area similar to 250m (2) g(-1)and narrow pore size distribution of 4-5 nm. TEM observations revealed the generation of spherical TiO2 nanoparticles (4-5 nm) assembled to form stable spongy scaffold having porous network structure with pore size 5-6 nm. Also, presence of a pronounced hysteresis loop in BET isotherm is indicative of a 3D-intersection network of the pores of size 4-5 nm. Further heat-treatment to the aged precursor at 400 degrees C/2 h in air modify pore network structure due to sintering of TiO2 particles as is observed in TEM studies and lowering thereby the surface area to 125 m(2) g(-1) (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Microstructure, porous materials, sol-gel processing, titania}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2005.02.014}, author = {Deshpande, S. B. and Potdar, H. S. and Khollam, Y. B. and Patil, K. R. and Pasricha, R. and Jacob, Nalini E.} } @article { ISI:000248795100038, title = {Titania nanoparticles synthesis in mesoporous molecular sieve MCM-41}, journal = {Journal of Colloid and Interface Science}, volume = {314}, number = {1}, year = {2007}, month = {OCT}, pages = {310-316}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, type = {Article}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

Nanocrystalline titanium oxide (TiO2) is one of the most useful oxide material, because of its widespread applications in photocatalysis, solar energy conversion, sensors and optoelectronics. The control of particle size and monodispersity of TiO2 nanoparticles is a challenging task. The use of MCM-41, an inorganic template of uniform pore size (2-10 nm), can overcome this difficulty and produce stable nanoparticles of uniform size and shape. Here, we demonstrate the synthesis of titania nanoparticles inside the pores of silica based MCM-41 forming a TiO2/Si-MCM composite. Composites are formed in the alcoholic medium by incipient wetness impregnation method. Titania particles of average 3 nm size are obtained. Effect of silica and titania precursors on the quality of nanoparticles has been investigated. The characterization of titania-MCM-41 composites has been carried out using a variety of techniques like UV-vis absorption spectroscopy, X-ray diffraction, FT-IR spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and photoluminescence spectroscopy. It has been found that the titania particles are co-ordinated with Si-MCM by Si-O-Ti covalent bond. (C) 2007 Elsevier Inc. All rights reserved.

}, keywords = {incipient wetness impregnation, Mesoporous material, template, titania}, issn = {0021-9797}, doi = {10.1016/j.jcis.2007.05.069}, author = {Lihitkar, N. B. and Abyaneh, Majid Kazemian and Samuel, V. and Pasricha, R. and Gosavi, S. W. and Kulkarni, S. K.} } @article { ISI:000245961800012, title = {Tungstophosphoric acid supported on titania: a solid acid catalyst in benzylation of phenol with benzylalcohol}, journal = {Catalysis Communictions}, volume = {8}, number = {5}, year = {2007}, month = {MAY}, pages = {800-806}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

{Benzylation of phenol with benzylalcohol was carried out in liquid phase over tungstophosphoric acid (TPA) supported on titania. The catalysts were prepared with different TPA (10-25\%) loading by wet impregnation method, were calcined at 700 degrees C and characterized by XRD, surface area, FTIR and acidity of the catalysts was measured by temperature programmed desorption of NH(3)-TPD, FTIR pyridine adsorption. The catalysts have been represented by a general formula as xPTiO(2)-Y (where x = wt\%

}, keywords = {benzyl ether, benzyl phenol, benzylalcohol, Heteropolyacid, phenyl benzyl ether, titania, tungstophosphoric acid}, issn = {1566-7367}, doi = {10.1016/j.catcom.2006.08.027}, author = {Kumbar, Suresh M. and Halligudi, Shivaraj B.} } @article { ISI:000253450900068, title = {Alkene epoxidation catalyzed by vanadomolybdophosphoric acids supported on hydrated titania}, journal = {Catalysis Communications}, volume = {9}, number = {5}, year = {2008}, month = {MAR}, pages = {931-938}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Vanadomolybdophosphoric acids wet-impregnated oil hydrated titania (TiO(2) - xH(2)O), make ail efficient catalytic system for the epoxidation of a variety of alkenes with organic solvent extracted TBHP as the oxidant. By,in appropriate choice of solvent, the catalyst call be reused at least three times without much loss in the activity for subsequent runs. XRD shows that the heteropoly acid is uniformly dispersed over the support and up to 15 wt\% loading of the heteropoly acid, no additional peak of the same call be seen in the XRD pattern of the catalyst. The reactivity varied with the nature of alkene but the major product was always the corresponding epoxide. The catalytic system is free of high temperature calcination steps and tedious multi-step procedures, normally encountered in the heter-ogenization of heteropoly acids. (c) 2007 Elsevier B.V. All rights reserved.

}, keywords = {alkenes, epoxidation, heteropoly acids, TBHP, titania, vanadomolybdophosphoric acids}, issn = {1566-7367}, doi = {10.1016/j.catcom.2007.09.022}, author = {Ingle, Rohit H. and Vinu, A. and Halligudi, Shivaraj B.} } @article { ISI:000257016800018, title = {Titania supported silicotungstic acid: an efficient solid acid catalyst for veratrole acylation}, journal = {Catalysis Communications}, volume = {9}, number = {10}, year = {2008}, month = {JUN}, pages = {2026-2029}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Titania supported silicotungstic acid (STA) with different STA loading (10-25 wt\%) and calcination temperature (650-750 degrees C) were prepared by wet impregnation method. The catalysts have been represented by a general formula xSTiO(2)y (where x denotes wt\%, S denotes STA and y denotes calcination temperature in degrees C). These catalysts were characterized by techniques such as X-ray diffraction, surface analysis, FTIR-pyridine and TPD-NH(3) and were used as heterogeneous solid acid catalysts in the liquid phase acylation of veratrole with acetic anhydride (Ac(2)O). It was found that 20STiO(2)700 gave the highest activity in acylation reaction due to its highest acidity. (C) 2008 Elsevier B.V. All rights reserved.

}, keywords = {acetic anhydride, Acylation, Silicotungstic acid, titania, veratrole}, issn = {1566-7367}, doi = {10.1016/j.catcom.2008.03.043}, author = {Waghmare, Nilesh G. and Kasinathan, Palraj and Amrute, Amol P. and Lucas, Nishita and Halligudi, Shivaraj B.} } @article { ISI:000263070700020, title = {Enhanced solar-radiation induced photocatalytic activity of surface-modified nanocrystalline anatase-titania}, journal = {Catalysis Letters}, volume = {128}, number = {1-2}, year = {2009}, month = {MAR}, pages = {137-143}, publisher = {SPRINGER}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Sol-gel derived pure nanocrystalline (similar to 20-30 nm) anatase-titania has been surface-modified by depositing silver(I) oxide and silver (predominantly the former) via UV-reduction process. The pure and surface-modified nanocrystalline anatase-titania have been characterized using different analytical techniques for determining the average nanocrystallite size, phase-contents, surface-chemistry, as well as the absorption and photoluminescence characteristics. It is demonstrated that, the latter exhibits an enhanced solar-radiation induced photocatalytic activity as compared to that of the former as a result of the absorption in the visible-region and enhanced photo-induced e(-)/h(+) life-time, both caused by the surface-deposition of silver(I) oxide and silver.

}, keywords = {Nanocrystalline, Photocatalysis, Silver, sol-gel, titania, UV-reduction}, issn = {1011-372X}, doi = {10.1007/s10562-008-9704-1}, author = {Priya, R. and Baiju, K. V. and Shukla, S. and Biju, S. and Reddy, M. L. P. and Patil, K. R. and Warrier, K. G. K.} } @article { ISI:000264925400047, title = {Novel electroless process for copper coating of flyash using titania/ultraviolet-radiation/metal catalyst-system}, journal = {Applied Surface Science}, volume = {255}, number = {13-14}, year = {2009}, month = {APR}, pages = {6696-6704}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A novel electroless process has been demonstrated in this investigation to coat the surface of flyash particles with a conducting metal such as copper. The conventional electroless process has been modified for this purpose by replacing the tin-palladium catalyst-system with the titania/ultraviolet-radiation/metal catalyst-system, where the metal is either copper or silver as demonstrated here. The mechanism of copper coating of flyash particles in an electroless bath, using the novel methods of surface-sensitization and surface-activation, has been systematically studied by monitoring changes in the surface-morphology, surface-chemistry, and surface-structure of flyash particles using the scanning electron microscope, energy dispersive analysis of X-rays, X-ray photoelectron spectroscope, and X-ray diffraction. It has been revealed that the novel electroless method involves coating the flyash particles with titania photocatalyst via sol-gel, which acts as a surface-sensitizer under the ultraviolet-radiation exposure for the subsequent surface-activation with the copper- or silver-clusters. The latter in turn acts as surface-catalyst for the subsequent Cu-coating in an electroless bath. The proposed mechanism of surface-sensitization and surface-activation of flyash particles using the novel catalyst-system has been compared with that using the conventional catalyst-system. (C) 2009 Elsevier B. V. All rights reserved.

}, keywords = {Copper, Electroless, Flyash, Photocatalysis, sol-gel, titania}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2009.02.066}, author = {Shijitha, T. and Baiju, K. V. and Shukla, S. and Patil, K. and Warrier, K. G. K.} } @article { ISI:000263073800048, title = {Template free synthesis of mesoporous TiO2 with high wall thickness and nanocrystalline framework}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {9}, number = {1, SI}, year = {2009}, month = {JAN}, pages = {371-377}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {

A simple procedure to prepare nanocrystalline mesoporous titania (meso-TiO2) is reported without any templating agent and it possesses a high BET surface area and a large pore wall thickness (11.3 nm) than that of meso-TiO2 prepared by other methods. Nanocrystalline meso-TiO2 also has been synthesized with hexadecylamine template for comparison through known procedure. The meso-TiO2 materials were characterized by X-ray diffraction, FT-IR, UV-Vis absorbance spectra, thermal analysis, SEM, HRTEM and textural properties through N-2 adsorption-desorption isotherms. Spherical shape particles in a range of few hundred nanometers are obtained in the template free method. Above systematic characterization provides direct indications toward the mechanism of formation of meso-TiO2 in the template free method. A comparison of the physical and textural properties indicates a possibility of coarse-tuning of the textural characteristics of mesoporous TiO2 by adopting different preparation methods.

}, keywords = {Mesopore, Mesopore Formation, Template-Free, Thick Wall, titania}, issn = {1533-4880}, doi = {10.1166/jnn.2009.J019}, author = {Kulkarni, Dhanashree G. and Murugan, A. Vadivel and Viswanath, Annamraju Kasi and Gopinath, Chinnakonda S.} } @article { ISI:000341405600003, title = {Ambient oxidation of benzene to phenol by photocatalysis on Au/Ti0.98V0.02O2: role of holes}, journal = {ACS Catalysis}, volume = {4}, number = {9}, year = {2014}, month = {SEP}, pages = {2844-2853}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A potential photocatalyst with 2 atom \% vanadium incorporated into the 1 lattice of disordered mesoporous titania, Ti0.98V0.02O2, (TV2) was synthesized. Au was deposited on TV2 (Au/TV2) through a photodeposition method. Structural, microscopy, and spectroscopy techniques support the incorporation of vanadium into the TiO2 lattice, and Au was deposited on the surfaces of TV2. Photocatalytic oxidation of benzene was conducted at ambient temperature under UV and/or visible light to demonstrate the catalytic activity of the Au/TV2 catalyst. The TV2 lattice exhibits a quantum jump in benzene to phenol oxidation compared to that of TiO2, highlighting the importance of V for oxidation. Introduction of Au onto TV2 further increases the benzene to phenol oxidation and phenol yield by a factor of 2 under UV light compared to those of bare TV2. No significant phenol production was observed in visible light with or without gold, indicating the role of gold is indirect toward charge separation and electron storage. Nano gold clusters on TV2 selectively store photoexcited electrons and in turn maximize holes utilization on TiO2. The high photocatalytic activity of Au/TV2 is mainly attributed to the presence of Schottky junctions, disordered mesoporosity, and short diffusion lengths for charge carriers.

}, keywords = {nano gold, phenol, Photocatalysis, Schottky junction, titania, Vanadium}, issn = {2155-5435}, doi = {10.1021/cs500724z}, author = {Devaraji, Perumal and Sathu, Naveen K. and Gopinath, Chinnakonda S.} } @article {46392, title = {Porous porphyrin organic polymer for visible light triggered hydrogen production}, journal = {Acta Crystallographica A-Foundation and Advances}, volume = {70}, year = {2014}, month = {MAY}, pages = {C1145}, type = {Meeting Abstract}, keywords = {Photocatalysis, Porous Porphyrin Organic Polymer (PPOP), titania}, issn = {2053-2733}, author = {Mukherjee, Gargi} } @article {44194, title = {Marginally hydrogenated triphasic titania nanotubes for effective visible-light photocatalytic hydrogen generation}, journal = {Energy Technology}, volume = {6}, year = {2018}, month = {FEB}, pages = {280-288}, type = {Article}, abstract = {

We report the first demonstration of hydrogen-annealed triphase TiO nanotubes (anatase-rutile-brookite) (T-ARB) as a visible-light-active photocatalyst for water splitting with high quantum efficiency. As-synthesized T-ARB was annealed under hydrogen atmosphere at 250 and 4508 degrees C for 2 h. We found that the tubular structures were retained in the hydrogenated TiO2 samples. It was observed that the concentrations of Ti3+ and the oxygen vacancies and their distribution significantly increased with respect to the hydrogen annealing temperature. Such changes in defects were found to be critical in enhancing the photocatalytic activity of the hydrogen-annealed triphase TiO2 nanotubes. The triphase TiO2 nanotubes hydrogen annealed at 450 degrees C were 16 times more efficient than pristine TiO2. Such an increase in the photocatalytic activity was explained by a triphase band diagram with defect states below the conduction band of each phase, which facilitated visible-light activity and easy transfer of charge carriers from one phase to another. Our study showed that the well-designed multiphase construction with oxygen vacancies enhanced the photocatalytic activity tremendously owing to the presence of a higher number of phase junctions.

}, keywords = {charge transfer, Defects, Hydrogenation, titania, water splitting}, issn = {2194-4288}, doi = {10.1002/ente.201700406}, author = {Preethi, Laguduva K. and Mathews, Tom and Walczak, Lukasz and Gopinath, Chinnakonda S.} }