Temperature dependence of the titanium oxide sols precipitation kinetics in the sol–gel process

Rivallin, Matthieu; Benmami, Mohamed; Gaunand, Alain; Kanaev, Andreï

doi:10.1016/j.cplett.2004.09.046

Cited by 22 publications

(46 citation statements)

References 9 publications

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“…It has been shown earlier experimentally 31 and theoretically 32 that the regime of Diffusion Limited Aggregation (DLA) results in the fractal growth with D f = 1.8 while Reaction Limited Aggregation (RLA) results in a slightly higher value of D f = 2.1. 33 The values obtained in our experiments correspond to the RLA aggregation regime and are markedly different from those characteristic of the induction period of pure TiO 2 (we note that in the latter case low-dimension structures of D f E 1.4 are observed in our experimental conditions 26 ). The observed fractal dimension about 2 may also result from a Brownian-walk aggregation process.…”

mentioning

confidence: 80%

“…Reproducible reaction kinetics and particle sizes were obtained in the sol-gel reactor [25][26][27] with temperature and humidity control. Two thermostatic stock solutions of equal volumes (50 mL) containing TTIP/2-propanol (A) and water/ 2-propanol (B) are injected into the static T-mixer at velocity varying from 2 to 12 m s À1 by applying an external pressure of dry nitrogen gas.…”

Section: Methodsmentioning

confidence: 99%

“…An explanation of (11) was proposed by Rivallin et al, 26 who has shown that the condensation reaction…”

Section: F Reaction Kinetics Involving Hyumentioning

confidence: 99%

“…Recently, we have proposed an improved sol-gel approach to the fabrication of chemically active TiO 2 clusters and nanoparticles based on the turbulent micromixing of reactive fluids containing titanium precursor and water. [25][26][27] Using a sol-gel reactor quasi-monodispersed titanium-oxo-alkoxy Ti x O y (O i Pr) z clusters and nanoparticles can be produced in macroscopic quantities. 28 By doping of these units we expect to attain a high homogeneity of the resultant bulk solids down to the scale as small as their size.…”

Section: Introductionmentioning

confidence: 99%

“…29 The induction kinetics exhibits weak temperature dependence and influences the morphology of the growing particles. 26 In the experimental conditions and temperature of 20 1C, the nuclei aggregate into quasi-linear chains of a low fractal dimension D f = 1.4.…”

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confidence: 99%

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TiO2 doping by hydroxyurea at the nucleation stage: towards a new photocatalyst in the visible spectral range

Azouani¹,

Tieng²,

Chhor³

et al. 2010

Phys. Chem. Chem. Phys.

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We report an original method of preparation of OCN-doped TiO 2 for photocatalysis in the visible spectral range. The preparation is achieved by a sol-gel route using titanium tetraisopropoxide precursor. Special attention was paid to fluid micromixing, which enables homogeneous reaction conditions in the reactor bulk and monodispersity of the produced clusters/nanoparticles. The dopant hydroxyurea (HyU, CH 4 N 2 O 2 ) is injected into the reactive fluid at the nucleation stage, which lasts tens of milliseconds. The doping results in a strong yellow coloration of the nanocolloids due to the absorption band in the spectral range 380-550 nm and accelerates the aggregation kinetics of both nuclei at the induction stage and sub-nuclei units (clusters) at the nucleation stage. FTIR, Raman and UV-visible absorption analyses show the formation of a stable HyU-TiO 2 complex. EXAFS spectra indicate no appreciable changes of the first-shell Ti atom environment. The doping agent takes available surface sites of TiO 2 clusters/ nanoparticles attaining B10% molar loading. The reaction kinetics then accelerates due to a longer collisional lifetime between nanoparticles induced by the formation of a weak QOÁ Á ÁTi bond. The OCN-group bonding to titanium atoms produces a weakening of the CQO double bond and a strengthening of the C-N and N-O bonds.

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mentioning

confidence: 80%

Section: Methodsmentioning

confidence: 99%

“…An explanation of (11) was proposed by Rivallin et al, 26 who has shown that the condensation reaction…”

Section: F Reaction Kinetics Involving Hyumentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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TiO2 doping by hydroxyurea at the nucleation stage: towards a new photocatalyst in the visible spectral range

Azouani¹,

Tieng²,

Chhor³

et al. 2010

Phys. Chem. Chem. Phys.

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Water‐Dispersible, Ligand‐Free, and Extra‐Small (<10 nm) Titania Nanoparticles: Control Over Primary, Secondary, and Tertiary Agglomeration Through a Modified “Non‐Aqueous” Route

Cadman

Pucci

Cellesi

et al. 2013

Adv Funct Materials

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Non‐aqueous routes to inorganic nanoparticles are supposedly based on the absence of water; here, this view is partially challenged, showing that the presence of water (or moisture) is probably necessary, and is surely useful to achieve a precise control over the growth/aggregation phenomena leading to titanium dioxide nanoparticles. This study is focused on the preparation of size‐controlled and ligand‐free titania (anatase) nanoparticles in water dispersion. This is achieved through a three‐step process: 1) production of primary (3–4 nm) nanoparticles from titanium alkoxides (Ti(OnPr)4, Ti(OnBu)4 or Ti(OiPr)4) in benzyl alcohol through the controlled addition of water; 2) thermal growth phase, where the aggregation of primary nanoparticles at 80 °C leads to secondary nanoparticles with a typical fractal dimension of 2.2–2.4; the primary particles are still identifiable as the individual crystallites composing the secondary nanoparticles; 3) precipitation/re‐dispersion in water, where secondary nanoparticles further agglomerate to yield tertiary nanoparticles. The size of the latter and their photocatalytic efficiency is primarily controlled by the nature of residual alkoxide chains; in particular, isopropoxide groups allow to produce anatase nanoparticles with an average size of 7–8 nm in water dispersion and in the absence of any stabilizing ligand, which is an unprecedented result.

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Nanostructuring of Titania Thin Films by a Combination of Microfluidics and Block‐Copolymer‐Based Sol–Gel Templating

Rawolle

Ruderer

Prams

et al. 2011

Small

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Sol-gel templating of titania thin films with the amphiphilic diblock copolymer poly(dimethyl siloxane)-block-methyl methacrylate poly(ethylene oxide) is combined with microfluidic technology to control the structure formation. Due to the laminar flow conditions in the microfluidic cell, a better control of the local composition of the reactive fluid is achieved. The resulting titania films exhibit mesopores and macropores, as determined with scanning electron microscopy, X-ray reflectivity, and grazing incidence small angle X-ray scattering. The titania morphology has three features that are beneficial for application in photovoltaics: 1) a large surface-to-volume ratio important for charge generation with disordered hexagonally arranged mesopores of 25 nm size and a film porosity of up to 0.79, 2) enhanced light scattering that enables the absorption of more light, and 3) a dense titania layer with a thickness of about 6 nm at the substrate (bottom electrode) to prevent short circuits. An optical characterization complements the structural investigation.

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Temperature dependence of the titanium oxide sols precipitation kinetics in the sol–gel process

Cited by 22 publications

References 9 publications

TiO2 doping by hydroxyurea at the nucleation stage: towards a new photocatalyst in the visible spectral range

TiO2 doping by hydroxyurea at the nucleation stage: towards a new photocatalyst in the visible spectral range

Water‐Dispersible, Ligand‐Free, and Extra‐Small (<10 nm) Titania Nanoparticles: Control Over Primary, Secondary, and Tertiary Agglomeration Through a Modified “Non‐Aqueous” Route

Nanostructuring of Titania Thin Films by a Combination of Microfluidics and Block‐Copolymer‐Based Sol–Gel Templating

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