Synthesis of submicrometer-sized titania spherical particles with a sol–gel method and their application to colloidal photonic crystals

Mine, Eiichi; Hirose, Mitsuaki; Nagao, Daisuke; Kobayashi, Yoshio; Konno, Mikio

doi:10.1016/j.jcis.2005.04.077

Cited by 93 publications

(60 citation statements)

References 15 publications

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“…[23][24][25] Monodispersed spherical TiO 2 structures can be successfully obtained by this procedure, but their low surface area and poor pore structure limit their application to DSCs. In this work, a specially designed solvothermal treatment was applied instead of the conventional calcination process to obtain the crystallized nanoporous TiO 2 spheres with ultrahigh surface area and well-developed nanopore structure.…”

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confidence: 99%

Formation of Highly Efficient Dye‐Sensitized Solar Cells by Hierarchical Pore Generation with Nanoporous TiO₂ Spheres

et al. 2009

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Recently, dye-sensitized solar cells (DSC) have attracted much attention with their low production costs of electricity and relatively high energy-conversion efficiencies. [1][2][3][4] One of the key elements in DSC is the nanoporous TiO 2 electrode, which transfers the electrons from the dye molecules to the transparent conductive-oxide (TCO) electrode and concurrently allows the electrolytes to diffuse to the anchored dyes. Typically, nanoparticles are utilized for the fabrication of the nanoporous TiO 2 layers on the TCO to obtain high surface areas and generate nanopored structures. [1,5,6] In this TiO 2 layer derived from nanoparticles, however, the electrons produced from the dye molecules have to pass through numerous grain boundaries in order to reach the TCO, and the transport of the electrolytes is not efficient due to the irregularity of the pores generated. To this point, the tailoring of TiO 2 nanostructures is a crucial aspect of increasing the current photovoltaic-conversion efficiency of DSC. [7][8][9][10][11][12][13][14][15][16][17][18][19] For the formation of an efficient DSC, a high surface area is prime and essential for the TiO 2 layer to load large amounts of dye molecules that will generate electrons by absorbing sun light. Second, the pores formed in the TiO 2 layer must be sufficiently large in size with excellent mutual connectivity for the efficient diffusion of electrolytes. Third, the defect level and the number of grain boundaries must be minimized to suppress the loss of electrons by recombination or back reaction. In general, however, these factors are not compatible with one another. For example, upon decreasing the size of the TiO 2 nanoparticles, the surface area of the fabricated nanoporous TiO 2 film is increased, and thus more dye molecules can be adsorbed. However, the average pore size is decreased simultaneously, and more defect sites and grain boundaries can be generated in the fabricated TiO 2 film. Therefore, it has been reported that the optimum particle size of TiO 2 has to be in the range of 12-20 nm. [5,6,[20][21][22] In this work, we designed a novel hierarchical pore structure that provides high surface area and large pore size at the same time. That is, nanoporous TiO 2 spheres with high surface area were synthesized and utilized to form the nanoporous TiO 2 electrode. As a result, two kinds of pores were successfully formed in the TiO 2 layer. Tiny internal pores were formed inside the TiO 2 sphere, while large external pores were generated by formation of the interstitial voids among the spherical structures. The large external pores can be used as a ''highway'' for electrolyte diffusion, as shown in Scheme 1. Therefore, it is expected that this porous spherical structure can provide both great adsorption of the dye molecules and efficient electrolyte diffusion at the same time.Sub-micrometer-sized TiO 2 spheres have often been prepared by sol-gel methods controlling the hydrolysis and condensation reactions, and their crystallized structures were formed by su...

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Formation of Highly Efficient Dye‐Sensitized Solar Cells by Hierarchical Pore Generation with Nanoporous TiO₂ Spheres

et al. 2009

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“…The monodisperse TiO 2 spheres were synthesized according to the reported procedures with some modifications [32]. In a typical procedure, 6.0 mmol TTIP stabilized in 10 mL anhydrous ethanol was dropwise added into a premixed solution of 50 mL ethanol and 40 mL acetonitrile containing 1.2 mmol MA and 24 mmol H 2 O.…”

Section: Preparation Of Tio 2 Tio 2 /Ag and Tio 2 @Ag Compositesmentioning

confidence: 99%

Modified photodeposition of uniform Ag nanoparticles on TiO2 with superior catalytic and antibacterial activities

Guo

et al. 2015

J Sol-Gel Sci Technol

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Photocatalytic reduction is a facile and effective route to deposit Ag nanoparticles (NPs) on TiO 2 . Nevertheless, it is difficult to produce Ag NPs that have small particle size and uniform distribution on TiO 2 to form core-shell structure TiO 2 @Ag composites by straightforward photodeposition. In this study, monodisperse TiO 2 spheres composed of anatase nanocrystals were directly employed as templates to deposit small and homogeneously dispersed Ag NPs by modified photodeposition procedure. To prove the feasibility of the innovative method, we evaluated the catalytic performance and bactericidal efficacy of the as-prepared samples based on the characterizations, since there is strong dependence between size and dispersion of Ag NPs and catalytic performance and inhibition of bacterial growth, where smaller and more highly dispersed Ag NPs displayed better antimicrobial and catalytic properties. The results indicate that the modified photodeposition route can effectively prevent TiO 2 spheres themselves from aggregating and Ag NPs from rapid overgrowing on the TiO 2 surface in the deposition process. The superior bactericidal and catalytic properties of the TiO 2 @Ag composites are largely attributed to the small and highly dispersed Ag NPs on TiO 2 spheres. Graphical Abstract

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“…(Bullough, 1996). In the fields of colloid and interface science and magnetic materials, applications are high-density recording materials (Harrell et al, 2005;Verdes et al, 2006), optical units (Iwayama, 2003;Reese, 2000;Mine, 2005;Furumi and Sakka, 2006a;Furumi and Sakka, 2006b), and surface modifying technology (Satoh and Sakuda, 2010). In other fields, there is a magnetically targeted drug delivery in the bioengineering field (Häfeli et al, 1997;Kuznetsov et al, 1999;Weingart et al, 2013), and a recovering technology for specific substances such as hazardous heavy metal molecules (environmental waste and pollutants) or valuable noble metal molecules from water (sea, lake, etc.)…”

Section: Introductionmentioning

confidence: 99%

Control of the orientational characteristics of disk-like hematite particles by a simple shear flow

Satoh

2016

Mechanical Engineering Letters

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We discuss the behavior of oblate spheroidal hematite particles in a simple shear flow. Magneto-rheological properties are strongly dependent on the magnetic field direction. For instance, a rod-like hematite particle suspension exhibits negative viscosity characteristics in a certain direction of an applied magnetic field. From this background, we here consider the case of an external magnetic field applied in the direction of the angular velocity vector of a simple shear flow. If the magnetic field is much more dominant than the thermal motion, the particle can almost freely rotate about the direction of the angular velocity vector. This characteristic rotational motion is suppressed or controlled by the shear flow more significantly with increasing shear rate.

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Synthesis of submicrometer-sized titania spherical particles with a sol–gel method and their application to colloidal photonic crystals

Cited by 93 publications

References 15 publications

Formation of Highly Efficient Dye‐Sensitized Solar Cells by Hierarchical Pore Generation with Nanoporous TiO₂ Spheres

Formation of Highly Efficient Dye‐Sensitized Solar Cells by Hierarchical Pore Generation with Nanoporous TiO₂ Spheres

Modified photodeposition of uniform Ag nanoparticles on TiO2 with superior catalytic and antibacterial activities

Control of the orientational characteristics of disk-like hematite particles by a simple shear flow

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Synthesis of submicrometer-sized titania spherical particles with a sol–gel method and their application to colloidal photonic crystals

Cited by 93 publications

References 15 publications

Formation of Highly Efficient Dye‐Sensitized Solar Cells by Hierarchical Pore Generation with Nanoporous TiO2 Spheres

Formation of Highly Efficient Dye‐Sensitized Solar Cells by Hierarchical Pore Generation with Nanoporous TiO2 Spheres

Modified photodeposition of uniform Ag nanoparticles on TiO2 with superior catalytic and antibacterial activities

Control of the orientational characteristics of disk-like hematite particles by a simple shear flow

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Formation of Highly Efficient Dye‐Sensitized Solar Cells by Hierarchical Pore Generation with Nanoporous TiO₂ Spheres

Formation of Highly Efficient Dye‐Sensitized Solar Cells by Hierarchical Pore Generation with Nanoporous TiO₂ Spheres