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Self-arrangement of nanoparticles toward crystalline metal oxides with high surface areas and tunable 3D mesopores.

Lee HI, Lee YY, Kang DU, Lee K, Kwon YU, Kim JM - Sci Rep (2016)

Bottom Line: We demonstrate a new design concept where the interaction between silica nanoparticles (about 1.5 nm in diameter) with titania nanoparticles (anatase, about 4 nm or 6 nm in diameter) guides a successful formation of mesoporous titania with crystalline walls and controllable porosity.At an appropriate solution pH (~1.5, depending on the deprotonation tendencies of two types of nanoparticles), the smaller silica nanoparticles, which attach to the surface of the larger titania nanoparticles and provide a portion of inactive surface and reactive surface of titania nanoparticles, dictate the direction and the degree of condensation of the titania nanoparticles, resulting in a porous 3D framework.Further crystallization by a hydrothermal treatment and subsequent removal of silica nanoparticles result in a mesoporous titania with highly crystalline walls and tunable mesopore sizes.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Sungkyunkwan University, Suwon, 440-746, Republic of Korea.

ABSTRACT
We demonstrate a new design concept where the interaction between silica nanoparticles (about 1.5 nm in diameter) with titania nanoparticles (anatase, about 4 nm or 6 nm in diameter) guides a successful formation of mesoporous titania with crystalline walls and controllable porosity. At an appropriate solution pH (~1.5, depending on the deprotonation tendencies of two types of nanoparticles), the smaller silica nanoparticles, which attach to the surface of the larger titania nanoparticles and provide a portion of inactive surface and reactive surface of titania nanoparticles, dictate the direction and the degree of condensation of the titania nanoparticles, resulting in a porous 3D framework. Further crystallization by a hydrothermal treatment and subsequent removal of silica nanoparticles result in a mesoporous titania with highly crystalline walls and tunable mesopore sizes. A simple control of the Si/Ti ratio verified the versatility of the present method through the successful control of mean pore diameter in the range of 2-35 nm and specific surface area in the ranges of 180-250 m(2) g(-1). The present synthesis method is successfully extended to other metal oxides, their mixed oxides and analogues with different particle sizes, regarding as a general method for mesoporous metal (or mixed metal) oxides.

No MeSH data available.


Related in: MedlinePlus

X-ray diffraction patterns (A) and Raman spectra (B): MT-0 (a), MT-25 (b), MT-50 (c), MT-75 (d), MT-100 (e), and MT-200 (f).
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f3: X-ray diffraction patterns (A) and Raman spectra (B): MT-0 (a), MT-25 (b), MT-50 (c), MT-75 (d), MT-100 (e), and MT-200 (f).

Mentions: Transmission electron micrographs (TEM) in Fig. 2 reveal the mesostructural evolution of MT-x materials as a function of Si/Ti molar ratio (x). Urchin-like particles composed of about 10 nm-thick nanorods were obtained in the absence of SNP (MT-0), as shown in Fig. 2(a). To the sharp contrast, the other samples prepared in the presence of SNPs reveal 3D porous networks. The apparent pore size is varied with the x-value. The morphological changes from the urchin-like particles to the porous particles are also confirmed by scanning electron micrographs (SEM) (Figure S1). The lattice fringes in the insets of Fig. 2 indicate that all the titania materials exhibit highly crystalline natures of frameworks. The lattice fringe of MT-0 material can be identified as the [101] view of rutile and those of MT-x (x = 25–200) materials correspond to the [110] views of anatase. The wide angle X-ray diffraction (XRD) patterns and the Raman spectra (Fig. 3) confirmed the phase identification by TEM data of Fig. 2. However, MT-25 and MT-50 materials show rutile phases as a minor component in their XRD patterns. Estimated by the Scherrer’s equation from the half widths of the diffraction peaks, the crystallite sizes are about 9 nm for MT-0 material and about 5 nm for MT-x (x = 25–200) materials. The blue-shifted Eg bands (bulk: 146 cm−1 → MT-x: 150 cm−1) and their peak widths of the Raman spectra of MT-x (x = 25–200) materials also indicate nanocrystalline anatase frameworks54555657.


Self-arrangement of nanoparticles toward crystalline metal oxides with high surface areas and tunable 3D mesopores.

Lee HI, Lee YY, Kang DU, Lee K, Kwon YU, Kim JM - Sci Rep (2016)

X-ray diffraction patterns (A) and Raman spectra (B): MT-0 (a), MT-25 (b), MT-50 (c), MT-75 (d), MT-100 (e), and MT-200 (f).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4759599&req=5

f3: X-ray diffraction patterns (A) and Raman spectra (B): MT-0 (a), MT-25 (b), MT-50 (c), MT-75 (d), MT-100 (e), and MT-200 (f).
Mentions: Transmission electron micrographs (TEM) in Fig. 2 reveal the mesostructural evolution of MT-x materials as a function of Si/Ti molar ratio (x). Urchin-like particles composed of about 10 nm-thick nanorods were obtained in the absence of SNP (MT-0), as shown in Fig. 2(a). To the sharp contrast, the other samples prepared in the presence of SNPs reveal 3D porous networks. The apparent pore size is varied with the x-value. The morphological changes from the urchin-like particles to the porous particles are also confirmed by scanning electron micrographs (SEM) (Figure S1). The lattice fringes in the insets of Fig. 2 indicate that all the titania materials exhibit highly crystalline natures of frameworks. The lattice fringe of MT-0 material can be identified as the [101] view of rutile and those of MT-x (x = 25–200) materials correspond to the [110] views of anatase. The wide angle X-ray diffraction (XRD) patterns and the Raman spectra (Fig. 3) confirmed the phase identification by TEM data of Fig. 2. However, MT-25 and MT-50 materials show rutile phases as a minor component in their XRD patterns. Estimated by the Scherrer’s equation from the half widths of the diffraction peaks, the crystallite sizes are about 9 nm for MT-0 material and about 5 nm for MT-x (x = 25–200) materials. The blue-shifted Eg bands (bulk: 146 cm−1 → MT-x: 150 cm−1) and their peak widths of the Raman spectra of MT-x (x = 25–200) materials also indicate nanocrystalline anatase frameworks54555657.

Bottom Line: We demonstrate a new design concept where the interaction between silica nanoparticles (about 1.5 nm in diameter) with titania nanoparticles (anatase, about 4 nm or 6 nm in diameter) guides a successful formation of mesoporous titania with crystalline walls and controllable porosity.At an appropriate solution pH (~1.5, depending on the deprotonation tendencies of two types of nanoparticles), the smaller silica nanoparticles, which attach to the surface of the larger titania nanoparticles and provide a portion of inactive surface and reactive surface of titania nanoparticles, dictate the direction and the degree of condensation of the titania nanoparticles, resulting in a porous 3D framework.Further crystallization by a hydrothermal treatment and subsequent removal of silica nanoparticles result in a mesoporous titania with highly crystalline walls and tunable mesopore sizes.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Sungkyunkwan University, Suwon, 440-746, Republic of Korea.

ABSTRACT
We demonstrate a new design concept where the interaction between silica nanoparticles (about 1.5 nm in diameter) with titania nanoparticles (anatase, about 4 nm or 6 nm in diameter) guides a successful formation of mesoporous titania with crystalline walls and controllable porosity. At an appropriate solution pH (~1.5, depending on the deprotonation tendencies of two types of nanoparticles), the smaller silica nanoparticles, which attach to the surface of the larger titania nanoparticles and provide a portion of inactive surface and reactive surface of titania nanoparticles, dictate the direction and the degree of condensation of the titania nanoparticles, resulting in a porous 3D framework. Further crystallization by a hydrothermal treatment and subsequent removal of silica nanoparticles result in a mesoporous titania with highly crystalline walls and tunable mesopore sizes. A simple control of the Si/Ti ratio verified the versatility of the present method through the successful control of mean pore diameter in the range of 2-35 nm and specific surface area in the ranges of 180-250 m(2) g(-1). The present synthesis method is successfully extended to other metal oxides, their mixed oxides and analogues with different particle sizes, regarding as a general method for mesoporous metal (or mixed metal) oxides.

No MeSH data available.


Related in: MedlinePlus