Synthesis and morphology of anatase and η-TiO2 nanoparticles

Nowadays, it is a great challenge to synthesize crystalline TiO2 nanostructures using low‐temperature methods without annealing stage. Such an approach allows to perform functional and structural modification in the formed crystalline phase by thermally unstable compounds, such as biomaterials, MOFs, dye sets in situ, which was previously considered impossible. In this work, we have developed and analyzed the effect of acidic peptization on formation of highly photoactive titania crystallites in an aqueous solution using titanium tetraisopropylate as a precursor. Acids with different dissociation degrees in water were used as peptizing mediators to determine the effect of protonation on sol formation. The dip‐coating films were obtained with consequent drying of the sols via evaporation of the solvent. The as‐prepared catalysts were characterized by X‐ray diffraction, AFM microscopy, UV–V is spectroscopy, Brunauer–Emmett–Teller surface area. The aggregate size of TiO2 in the colloidal suspension solution was measured by dynamic light scattering. Photocatalytic activity of films was studied by decomposition of Rhodamine B dye. It is found that the size of colloids in an aqueous solution is proportional to the protonation degree of the surface of particles and does not depend on the [Ti4+]/[H+] ratio, and peptization under weakly acidic conditions leads to anisotropic rod‐like nanoparticles. The highest photocatalytic activity was exhibited by the TiO2–HCl‐based coatings, ~3.5 times higher than that of the Acet.‐prepared sample.

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“…Obtaining titania by sulfate method leads to forming a mixture of crystalline Ti(SO 4 ) 2 and anatase, Fig. (d), sometimes called a η‐phase …”

Section: Resultsmentioning

confidence: 99%

Effect of Acidic Peptization on Formation of Highly Photoactive TiO₂ Films Prepared without Heat Treatment

Vinogradov¹,

Vinogradov²

2013

J. Am. Ceram. Soc.

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“…4a indicates the position of the η-phase peak at 2θ ~ 33° with d = 2.7 Å in the X-ray-diffraction profile, which is unique (does not coincide with anatase peaks) for this phase. Note that the analysis of the samples containing the η-TiO 2 phase but exhibiting a stronger reflection in diffraction patterns in the smallangle spectral range in comparison with sample 1 [7,31] revealed a characteristic reflection with d ~2.7 Å in the electron diffraction pattern, along with other reflections related to the η phase. This can be explained by the smaller amount of the η phase in sample 1 in comparison with the samples studied in [7,31] and its nonuniform distribution over the sample volume.…”

Section: Resultsmentioning

confidence: 99%

“…According to [2], one distinctive feature of η-TiO 2 is the existence of characteristic diffraction peaks at 2θ ~ 5° and ~33° (CuK α radiation). According to the data of [4][5][6][7], the structure of η modification is a superstructure with respect to the anatase structure with approximately doubled unit-cell parameter c. The η-TiO 2 polymorph is an anatase "precursor"; it is formed in the beginning of anatase synthesis during the hydrolysis of titanyl sulfate in a sulfuric acid medium (under nonequilibrium conditions); while hydrolysis continues in the absence of stabilizing ions, it is transformed into anatase. The high reactivity of the η-TiO 2 surface is likely to be caused by its higher (when compared with anatase) degree of hydration [2,3].…”

Section: Introductionmentioning

confidence: 99%

Effect of methylene blue modification on the structural, morphological, and photocatalytic properties of nanosized η-TiO2

et al. 2015

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The structural and morphological features of samples containing titanium dioxide, obtained by the sulfate method in the presence of methylene blue dye МеВ (sample with η-TiO 2 ) and in its absence (sample with anatase), have been determined using a complex of analytical methods. For the sample with η-TiO 2 , the sizes of titanium dioxide crystallites (5.0(2) nm) are smaller than the nanoparticle sizes (5.5-9.0 nm), which does not exclude their defect structure. This sample exhibited a higher tendency of nanoparticles to agglomeration (the presence of strong bonds between nanoparticles) and a low tendency to aggregation (the presence of weak bonds). It is shown that a МеВ-modified sample with η-TiO 2 has high photocatalytic activity in the visible spectral range in the model reaction of methyl orange dye decomposition.

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“…Currently, titanium dioxide is of significant interest, both as an object of fundamental research [1][2][3][4] and material for various practical applications [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Nanosized powders of titanium dioxide are used in metallurgy [5,6], electronics [7][8][9], polymer industry [10,11], photovoltaics [12][13][14][15], and biomedicine [16,17].…”

Section: Introductionmentioning

confidence: 99%

“…Another important area for nanocrystalline titanium dioxide is photocatalysis [13,[18][19][20][21][22][23]. Since the properties of TiO 2 nanoparticles strongly depend on phase composition, morphology and surface structure, many scientific papers focus on formation mechanism and design of various titanium oxide nanocrystals [1,[18][19][20][21][22][23][24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Effect of heterogeneous inclusions on the formation of TiO2 nanocrystals in hydrothermal conditions

Zlobin¹,

Krasilin²,

Almjasheva³

2019

Nanosystems: Phys. Chem. Math.

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The effects of heterogeneous impurities on the process of titanium dioxide nanoparticle formation during hydrothermal synthesis and photocatalytic properties of synthesized particles were studied. Pre-formed TiO 2 nanoparticles of anatase and rutile modifications were used as the heterogeneous impurity. It is shown that the heterogeneous impurities may be considered neither as geometric constraints precluding the crystallization, nor as crystallization centers.

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Synthesis and morphology of anatase and η-TiO2 nanoparticles

Cited by 19 publications

References 7 publications

Effect of Acidic Peptization on Formation of Highly Photoactive TiO₂ Films Prepared without Heat Treatment

Effect of Acidic Peptization on Formation of Highly Photoactive TiO₂ Films Prepared without Heat Treatment

Effect of methylene blue modification on the structural, morphological, and photocatalytic properties of nanosized η-TiO2

Effect of heterogeneous inclusions on the formation of TiO2 nanocrystals in hydrothermal conditions

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Synthesis and morphology of anatase and η-TiO2 nanoparticles

Cited by 19 publications

References 7 publications

Effect of Acidic Peptization on Formation of Highly Photoactive TiO2 Films Prepared without Heat Treatment

Effect of Acidic Peptization on Formation of Highly Photoactive TiO2 Films Prepared without Heat Treatment

Effect of methylene blue modification on the structural, morphological, and photocatalytic properties of nanosized η-TiO2

Effect of heterogeneous inclusions on the formation of TiO2 nanocrystals in hydrothermal conditions

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Product

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Effect of Acidic Peptization on Formation of Highly Photoactive TiO₂ Films Prepared without Heat Treatment

Effect of Acidic Peptization on Formation of Highly Photoactive TiO₂ Films Prepared without Heat Treatment