Synthesis of titanium dioxide particles in supercritical CO2

Tadros, M. E.; Adkins, C.L.J.; Russick, Edward Mark; Youngman, Michael P.

doi:10.1016/s0896-8446(96)90029-7

Cited by 38 publications

(30 citation statements)

References 11 publications

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“…CVD, on the other hand, requires the use of highly volatile source materials. Also, a singre supercritical fluid can be made to simultaneously deposit a multi-component In addition to metals, other materials of interest to the microelectronics industry have been synthesized in supercritical fluids, including Si02 films in supercritical alcohol, [21] nitrides and sulfides in supercritical ammonia, [22,23,24] sulfides in supercritical amines, [25,26] transition metal oxides in supercritical water, [27] in SCCO2, [28] and in supercritical alcoho1, [29,30] and rare-earth-based phosphors in SCCO2. [3 13.…”

Section: Supercritical C02 As a Surface-cleaning Solventmentioning

confidence: 99%

CO{sub 2}-based supercritical fluids as environmentally-friendly processing solvents

Rubin¹,

Davenhall²,

Taylor³

et al. 1999

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Section: Supercritical C02 As a Surface-cleaning Solventmentioning

confidence: 99%

CO{sub 2}-based supercritical fluids as environmentally-friendly processing solvents

Rubin¹,

Davenhall²,

Taylor³

et al. 1999

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“…Studies have also been performed on the SAS preparation of TiO 2 in both batch and semi-continuous modes using acetylacetonate and alkoxide precursors [33][34][35][36]. These studies include the use of supercritical CO 2 to induce hydrolysis of alkoxides [33] and also to facilitate the polymerisation of alkoxides with acetic acid, akin to a sol-gel process [36]. Calcination of these precursors has resulted in various TiO 2 morphologies and significantly different anatase/rutile compositions.…”

Section: Introductionmentioning

confidence: 99%

Supercritical antisolvent precipitation of TiO2 with tailored anatase/rutile composition for applications in redox catalysis and photocatalysis

Marín

Ishikawa

Bahruji

et al. 2015

Applied Catalysis A: General

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Keywords:TiO2 Supercritical CO2 Photocatalysis Direct synthesis of hydrogen peroxide Alcohol oxidation a b s t r a c t TiO 2 with tailored anatase/rutile composition has been prepared from the supercritical antisolvent (SAS) precipitation of a range of titanium alkoxides. The calcination of the SAS TiO 2 was monitored by in situ powder X-ray diffraction to determine the optimal calcination conditions for the formation of a mixed anatse/rutile phase TiO 2 . The SAS precipitated material calcined at 450 • C produced a predominantly anatase support while calcination at 750 • C resulted in a 90 wt% anatase and 10 wt% rutile TiO 2 . 5 wt% AuPd was added to the SAS TiO 2 using an impregnation technique, with exceptional dispersion of the metals being observed by transmission electron microscopy. Mean metal particle sizes were determined to be below 1 nm for both anatase and anatase/rutile SAS TiO 2 materials. These catalysts were found to be highly active for the selective oxidation of benzyl alcohol and the direct synthesis of hydrogen peroxide. In addition the anatase/rutile SAS TiO 2 was found to have comparable activity to commercial anatase/rutile mixed phase TiO 2 for the photocatalytic splitting of water for hydrogen production.

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“…1 As a result, scCO 2 has been widely used for chemical processes, e.g., extraction and separation, chemical reactions, and material processing. [2][3][4][5][6][7] Recently, direct sol-gel reactions in scCO 2 have attracted much attention for synthesizing oxide nanomaterials. As examples, SiO 2 monolithic aerogels and nanoparticles have been synthesized by the reaction of silicon alkoxides with formic/acetic acid; 8-10 TiO 2 and ZrO 2 nanofibers, nanospheres, and mesoporous monoliths have been produced by polycondensation of metal alkoxides with either acetic acid or water droplets with the aid of surfactants.…”

Section: Introductionmentioning

confidence: 99%

Infrared and Computational Studies on Interactions of Carbon Dioxide and Titania Nanoparticles with Acetate Groups

Sui

Charpentier

2009

J. Phys. Chem. C

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Understanding the nature of the interactions between growing colloidal nanoparticles and CO 2 molecules is of importance for designing and synthesizing well-defined oxide nanoarchitectures during sol-gel processing in supercritical CO 2 (scCO 2 ). In this research, attenuated total reflective Fourier transform infrared (ATR-FTIR) spectrometry was used for studying the interactions between CO 2 molecules and metal acetate bidentate groups. Freshly synthesized aerogels formed using Ti and Zr alkoxides were treated with CO 2 and subsequently depressurized to remove the strong infrared absorbance of bulk CO 2 . The IR spectra from the depressurized TiO 2 and ZrO 2 samples were compared to the IR spectra from the respective calcined samples showing that the ν 2 bending peak of the CO 2 split due to Lewis acid and base interactions. Further verification of the spectral assignments and the bonding analysis were obtained by theoretical calculations using the density functional theory (DFT) method and TiO 2 nanocluster models. This research demonstrates that the metal acetate group on the Ti and Zr polycondensates is CO 2 -philic, and therefore these colloidal particles can be stabilized in scCO 2 .

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Synthesis of titanium dioxide particles in supercritical CO2

Cited by 38 publications

References 11 publications

CO{sub 2}-based supercritical fluids as environmentally-friendly processing solvents

CO{sub 2}-based supercritical fluids as environmentally-friendly processing solvents

Supercritical antisolvent precipitation of TiO2 with tailored anatase/rutile composition for applications in redox catalysis and photocatalysis

Infrared and Computational Studies on Interactions of Carbon Dioxide and Titania Nanoparticles with Acetate Groups

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