Nano-sized blue spectral shift in sol–gel derived mesoporous titania films

ABSTRACTMesoporous titania films are prepared via the polymer-template assisted sol-gel synthesis at low temperatures, using the titania precursor ethylene glycol-modified titanate (EGMT) and the diblock copolymer polystyrene-block-polyethyleneoxide (PS-b-PEO). UV-irradiation is chosen as a low temperature technique to remove the polymer template and thereby to obtain titania sponge-like nanostructures at processing temperatures below 100 °C. After different UV irradiation times, ranging for 0 h to 24 h, the surface and inner morphologies of the titania films are studied with scanning electron microscopy (SEM) and grazing incidence small-angle x-ray scattering (GISAXS), respectively. The evolution of the band gap energies is investigated using ultraviolet/visible (UV/Vis) spectroscopy. The findings reveal that 12 h UV-treatment is sufficient to remove the polymer template from the titania/PS-b-PEO composite films with a thickness of 80 nm, and the determined bad gap energies indicate an incomplete crystallization of the titania nanostructures.

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Thermal Conductivity of Highly Ordered Amorphous and Crystalline Mesoporous Titania Thin Films

2010 14th International Heat Transfer Conference, Volume 6 ◽

10.1115/ihtc14-23161 ◽

2010 ◽

Author(s):

Thomas Coquil ◽

Laurent Pilon ◽

Christian Reitz ◽

Torsten Brezesinski ◽

Joseph E. Nemanick ◽

...

Keyword(s):

Thin Films ◽

Thermal Conductivity ◽

Film Thickness ◽

Pore Size ◽

Wall Thickness ◽

Sol Gel ◽

Atomic Scale ◽

Mesoporous Titania ◽

Titania Films ◽

The Cross

This paper reports the cross-plane thermal conductivity of amorphous and crystalline templated mesoporous titania thin films synthesized by evaporation-induced self-assembly. Both sol-gel and nanocrystal-based films were considered, with respective average porosities of 30% and 35%. The pore diameter ranged from 7 to 25 nm and film thickness from 60 to 370 nm while the average wall thickness varied from 3 to 25 nm. Nanocrystals in crystalline mesoporous films featured diameters between 9 and 13 nm. The thermal conductivity was measured at room temperature using the 3ω method. The experimental setup and the associated analysis were validated by comparing the thermal conductivity measurements with data reported in the literature for dense titania films with thickness ranging from 95 to 1000 nm. The cross-plane thermal conductivity of the amorphous mesoporous titania thin films did not show strong dependence on pore size, wall thickness, or film thickness. This can be attributed to the high atomic scale disorder of amorphous materials. Heat is thus mainly carried by localized non-propagating vibrational modes. The average thermal conductivity of the amorphous mesoporous titania films was identical to that of the nanocrystal-based films and equal to 0.37 W/m.K. Thermal conductivity of sol-gel crystalline mesoporous titania thin films was significantly larger than that of their amorphous counterparts. It also depended on the organic template used to make the films. The results indicated that the pore size was not an important factor. Instead thermal conductivity depended only on porosity, crystallinity, nanocrystal size and connectivity.

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Thermal Conductivity of Ordered Mesoporous Titania Films Made from Nanocrystalline Building Blocks and Sol−Gel Reagents

The Journal of Physical Chemistry C ◽

10.1021/jp103251t ◽

2010 ◽

Vol 114 (29) ◽

pp. 12451-12458 ◽

Cited By ~ 35

Author(s):

Thomas Coquil ◽

Christian Reitz ◽

Torsten Brezesinski ◽

E. Joseph Nemanick ◽

Sarah H. Tolbert ◽

...

Keyword(s):

Thermal Conductivity ◽

Sol Gel ◽

Building Blocks ◽

Mesoporous Titania ◽

Ordered Mesoporous ◽

Titania Films

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Tailoring Mesoporous Titania Features by Ultrasound-Assisted Sol-Gel Technique: Effect of Surfactant/Titania Precursor Weight Ratio

Nanomaterials ◽

10.3390/nano11051263 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1263

Author(s):

Elvira Mahu ◽

Cristina Giorgiana Coromelci ◽

Doina Lutic ◽

Iuliean Vasile Asaftei ◽

Liviu Sacarescu ◽

...

Keyword(s):

Photocatalytic Activity ◽

Sol Gel ◽

Weight Ratio ◽

Soft Template ◽

Synthesis Process ◽

Mesoporous Titania ◽

Cavitation Effect ◽

Titania Precursor ◽

Gel Technique ◽

Ultrasound Assisted

A mesoporous titania structure has been prepared using the ultrasound-assisted sol-gel technique in order to find out a way to tailor its structure. The TiO2 obtained was compared to the same version of titania but synthesized by a conventional sol-gel method with the objective of understanding the effect of ultrasound in the synthesis process. All synthesis experiments were focused on the preparation of a titania photocatalyst. Thus, the anatase photocatalytic active phase of titania was proven by X-ray diffraction. Additionally, the ultrasonation treatment proved to increase the crystallinity of titania samples, being one of the requirements to having good photocatalytic activity for titania. The influence of surfactant/titania precursor weight ratio on the structural (XRD), textural (N2-sorption measurements), morphological (TEM), surface chemistry (FTIR) and optical properties (UVDR) was investigated. It was observed that the crystallite size, specific surface area, band gap energy and even photocatalytic activity was affected by the synergism occurring between cavitation effect and the surfactant/titania precursor weight ratio. The study yielded interesting great results that could be considered for further application of ultrasound to tailor mesoporous titania features via sol-gel soft template synthesis, against conventional sol-gel process.

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Assembly of thin mesoporous titania films and their effects on the voltammetry of weakly adsorbing redox systems

Journal of Electroanalytical Chemistry ◽

10.1016/j.jelechem.2005.02.017 ◽

2005 ◽

Vol 579 (2) ◽

pp. 267-275 ◽

Cited By ~ 13

Author(s):

Katy J. McKenzie ◽

Pauline M. King ◽

Frank Marken ◽

Catherine E. Gardner ◽

Julie V. Macpherson

Keyword(s):

Mesoporous Titania ◽

Redox Systems ◽

Titania Films

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Induced Crystallization In CW Laser-Irradiated Sol-Gel Deposited Titania Films

MRS Proceedings ◽

10.1557/proc-321-393 ◽

1993 ◽

Vol 321 ◽

Cited By ~ 3

Author(s):

Gregory J. Exarhos ◽

Nancy J. Hess

Keyword(s):

Laser Fluence ◽

Sol Gel ◽

Film Stress ◽

Amorphous Films ◽

Time Resolved ◽

Cw Laser ◽

Residual Film ◽

Titania Films ◽

Induced Crystallization ◽

Nanograin Size

AbstractIsothermal annealing of amorphous TiO2 films deposited from acidic sol-gel precursor solutions results in film densification and concomitant increase in refractive index. Subsequent heating above 300°C leads to irreversible transformation to an anatase crystalline phase. Similar phenomena occur when such amorphous films are subjected to focused cw laser irradiation. Controlled variations in laser fluence are used to density or crystallize selected regions of the film. Low fluence conditioning leads to the evolution of a subtle nanograin-size morphology, evident in AFM images, which appears to retard subsequent film crystallization when such regions are subjected to higher laser fluence. Time-resolved Raman spectroscopy has been used to characterize irradiated regions in order to follow the crystallization kinetics, assess phase homogeneity, and evaluate accompanying changes in residual film stress.

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Choline chloride–zinc chloride ionic liquid as a green template for the sol–gel synthesis of mesoporous titania

RSC Advances ◽

10.1039/c6ra28478g ◽

2017 ◽

Vol 7 (17) ◽

pp. 10081-10091 ◽

Cited By ~ 7

Author(s):

T. Preethi ◽

M. P. Padmapriya ◽

B. Abarna ◽

G. R. Rajarajeswari

Keyword(s):

Ionic Liquid ◽

Zinc Chloride ◽

Choline Chloride ◽

Sol Gel ◽

Mesoporous Titania ◽

Anatase Titania ◽

Sol Gel Synthesis

Choline chloride–zinc chloride ionic liquid has been used as a green template to synthesis highly crystalline mesoporou anatase titania.

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SYNTHESIS OF MESOPOROUS TITANIA BY POTATO STARCH TEMPLATED SOL-GEL REACTIONS AND ITS CHARACTERIZATION

Indonesian Journal of Chemistry ◽

10.22146/ijc.21476 ◽

2010 ◽

Vol 10 (1) ◽

pp. 26-31 ◽

Cited By ~ 3

Author(s):

Canggih Setya Budi ◽

Indriana Kartini ◽

Bambang Rusdiarso

Keyword(s):

Water Solution ◽

Potato Starch ◽

Sol Gel ◽

Building Blocks ◽

Mesoporous Tio2 ◽

Mesoporous Titania ◽

Tio2 Powder ◽

Nanocrystalline Tio2 ◽

Template Removal ◽

Starch Gel

Mesoporous titania powders with high-order crystalline building blocks had been synthesized through the sol-gel process using potato starch gel template. Internal spongelike pore structure of starch gel template was generated by heating the starch granules at 95 °C in water solution and freezing the starch gel at -15 °C. The synthesis routes were performed by immersing the starch gel template for 4 days into the white colloidal solution of TiO2 nanoparticles, which were prepared by hydrolyzing titanium (IV) tetraisopropoxide (TTIP) in ethanol at pH 1. Mesoporous TiO2 powders were obtained by two different ways of template removal, performed by calcination of the TiO2-starch composites at 600 °C for 4 h or combination of extraction with ethanol-HCl (2:1) at 80 °C and calcination at 500 °C for 4 h. Fourier Transform Infra Red (FT-IR) spectra shows both of template removal methods result in decreasing of characteristic vibrational band of the starch hydrocarbon on the resulted TiO2 powders. The X-Ray Diffraction (XRD) pattern imply that the concentrations of starch gel template influence the anatase crystallite peaks intensity of the synthesized TiO2 powders. TiO2 templated by 20% of starch sponges gel has highest intensity of anatase crystallite. Scherrer calculation inidicated that anatase particle size has nanoscale dimmension up to 12.96 nm. The nano-architecture feature of mesoporous TiO2 scaffolds was also evaluated by the Scanning Electron Microscope (SEM). It is shown that mesoporous TiO2 framework consist of nanocrystalline TiO2 particles as buiding blocks. The N2 adsorption-desorption isotherm curves assign that TiO2 powder resulted from extraction-calcination route has higher mesoporosity than that of only calcinated. The synthesized mesoporous TiO2 powder exhibits high Brunauer-Emmet-Teller (BET) specific surface area up to 65.65 m2/g. Keywords: mesoporous TiO2, potato starch, template

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