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Kotaro Shimasaki

Bio: Kotaro Shimasaki is an academic researcher from Fukuoka Institute of Technology. The author has contributed to research in topics: Mesoporous material & Mesoporous silica. The author has an hindex of 5, co-authored 6 publications receiving 84 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, photoactive titania (titanium dioxide) nanoparticles are successfully hybridized with an optimized amount of mesoporous silica (silicon dioxide) to realize drastic improvement of photocatalitic activity of the titania nanoparticles.
Abstract: Here we demonstrate that photoactive titania (titanium dioxide) nanoparticles are successfully hybridized with an optimized amount of mesoporous silica (silicon dioxide) nanoparticles to realize drastic improvement of photocatalitic activity of the titania nanoparticles. Various types of mesoporous silica/titania composites are prepared by changing the amounts of doped mesoporous silica. Low-angle XRD patterns and N2 adsorption-desorption isotherms reveal that the original mesostructures and pore sizes of mesoporous silica nanoparticles are well maintained even after hybridization with the titania nanoparticles. From SEM and TEM observation, it is confirmed that both the nanoparticles are homogeneously dispersed in the composite matrix. The obtained mesoporous silica/titania composites show excellent photocatalytic activity in the decomposition of methylene blue (MB), in comparison with titania nanoparticles without mesoporous silica. By hybridization with mesoporous silica, the photogenerated radicals from titania surfaces can efficiently react with many MB molecules captured inside the mesopores.

32 citations

Journal ArticleDOI
TL;DR: It is reported that colloidal nanosheets of a Dion–Jacobson type layered perovskites, Ca2Nb3O10, adopt a LC phase with a mesoscale structure by condensation after the conventional preparation of the nanosheet colloid.
Abstract: Three nanosheets to the wind: A liquid‐crystal phase in the condensed colloids of semiconductor nanosheets of a layered perovskite Ca2Nb3O10− was synthesized and characterized. Their properties and functionalities are tunable for further fundamental studies and potential applications as smart soft materials.

19 citations

Journal ArticleDOI
TL;DR: It is demonstrated that mesoporous silicas (MPSs) can be used as effective "topological crosslinkers" for poly(N-isopropylacrylamide) (PNIPA) hydrogels to improve the mechanical property.
Abstract: Here it is demonstrated that mesoporous silicas (MPSs) can be used as effective topological crosslinkers for poly(N-isopropylacrylamide) (PNIPA) hydrogels to improve the mechanical property. Three-dimensional bicontinuous mesporous silica is found to effectively reinforce the PNIPA hydrogels, as compared to nonporous silica and two-dimensional hexagonally ordered mesoporous silica.

15 citations

Journal ArticleDOI
TL;DR: In this paper, the authors synthesize various kinds of mesoporous Nb2O5 samples by changing surfactants (P123 and Brij 56), followed by calcination (from 400 to 500 and 600 degrees C).
Abstract: We synthesize various kinds of mesoporous Nb2O5 samples by changing surfactants (P123 and Brij 56), followed by calcination (from 400 to 500 and 600 degrees C). The effect of these parameters helps to produce a well-defined mesoporous framework with crystallinity. The mesoporous Nb2O5 samples are well characterized by using small-angle X-ray scattering (SAXS) measurements, N2 adsorption-desorption isotherms, and wide-angle XRD measurements. In a P123 system, the frameworks are well crystallized to the TT-phase (pseudo-hexagonal) by calcination at 500 degrees C with retention of the mesoporous structures. In the Brij 56 system, after calcination at 500 degrees C, the framework is well retained in an amorphous state. It is proved that the thick walls prepared with P123 are easily crystallized in comparison to thin walls prepared with Brij 56. Furthermore, we investigate the photocatalytic activity by using several types of mesoporous Nb2O5 prepared with P123. All these mesoporous Nb2O5 samples show photocatalytic activity with their decomposition reaction of methylene blue (MB) molecules. It is concluded that the reaction rates depend on their crystallinities in the frameworks, surface areas, and average mesopore sizes.

12 citations

Journal ArticleDOI
TL;DR: Rational design of future hybrid photocatalyst with precisely controlled nanostructure will be possible by optimization of the synthetic procedure and careful study of the adsorption and photocatalytic properties.
Abstract: Nanoporous silica/titania nanoparticles composites with relatively large TiO2 content are successfully synthesized by aerosol-assisted co-assembly. By the hybridization of titania with nanoporous silica having high surface area, both the adsorption capability and the reaction rates for the photocatalytic decomposition of methylene blue (MB) are dramatically improved in comparison with unmodified titania nanoparticles without nanoporous silica. Through the quantitative evaluation of the amount of adsorbed and photo-decomposed organic molecule throughout the reaction process, the role of nanoporous silica layers on titania surface is clarified. Rational design of future hybrid photocatalyst with precisely controlled nanostructure will be possible by optimization of our synthetic procedure and careful study of the adsorption and photocatalytic properties.

9 citations


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Journal ArticleDOI
26 Mar 2013-ACS Nano
TL;DR: The properties and advantages of single-, few-, and many-layer 2D materials in field-effect transistors, spin- and valley-tronics, thermoelectrics, and topological insulators, among many other applications are highlighted.
Abstract: Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...

4,123 citations

Journal ArticleDOI
21 Jun 2013-Science
TL;DR: A number of methods have been developed to exfoliate layered materials in order to produce monolayer nanosheets, which are ideal for applications that require surface activity.
Abstract: Background Since at least 400 C.E., when the Mayans first used layered clays to make dyes, people have been harnessing the properties of layered materials. This gradually developed into scientific research, leading to the elucidation of the laminar structure of layered materials, detailed understanding of their properties, and eventually experiments to exfoliate or delaminate them into individual, atomically thin nanosheets. This culminated in the discovery of graphene, resulting in a new explosion of interest in two-dimensional materials. Layered materials consist of two-dimensional platelets weakly stacked to form three-dimensional structures. The archetypal example is graphite, which consists of stacked graphene monolayers. However, there are many others: from MoS 2 and layered clays to more exotic examples such as MoO 3 , GaTe, and Bi 2 Se 3 . These materials display a wide range of electronic, optical, mechanical, and electrochemical properties. Over the past decade, a number of methods have been developed to exfoliate layered materials in order to produce monolayer nanosheets. Such exfoliation creates extremely high-aspect-ratio nanosheets with enormous surface area, which are ideal for applications that require surface activity. More importantly, however, the two-dimensional confinement of electrons upon exfoliation leads to unprecedented optical and electrical properties. Liquid exfoliation of layered crystals allows the production of suspensions of two-dimensional nanosheets, which can be formed into a range of structures. (A) MoS 2 powder. (B) WS 2 dispersed in surfactant solution. (C) An exfoliated MoS 2 nanosheet. (D) A hybrid material consisting of WS 2 nanosheets embedded in a network of carbon nanotubes. Advances An important advance has been the discovery that layered crystals can be exfoliated in liquids. There are a number of methods to do this that involve oxidation, ion intercalation/exchange, or surface passivation by solvents. However, all result in liquid dispersions containing large quantities of nanosheets. This brings considerable advantages: Liquid exfoliation allows the formation of thin films and composites, is potentially scaleable, and may facilitate processing by using standard technologies such as reel-to-reel manufacturing. Although much work has focused on liquid exfoliation of graphene, such processes have also been demonstrated for a host of other materials, including MoS 2 and related structures, layered oxides, and clays. The resultant liquid dispersions have been formed into films, hybrids, and composites for a range of applications. Outlook There is little doubt that the main advances are in the future. Multifunctional composites based on metal and polymer matrices will be developed that will result in enhanced mechanical, electrical, and barrier properties. Applications in energy generation and storage will abound, with layered materials appearing as electrodes or active elements in devices such as displays, solar cells, and batteries. Particularly important will be the use of MoS 2 for water splitting and metal oxides as hydrogen evolution catalysts. In addition, two-dimensional materials will find important roles in printed electronics as dielectrics, optoelectronic devices, and transistors. To achieve this, much needs to be done. Production rates need to be increased dramatically, the degree of exfoliation improved, and methods to control nanosheet properties developed. The range of layered materials that can be exfoliated must be expanded, even as methods for chemical modification must be developed. Success in these areas will lead to a family of materials that will dominate nanomaterials science in the 21st century.

3,127 citations

Journal ArticleDOI
TL;DR: In this review, the general principles of templated synthesis using various types of templer techniques to produce nanoporous materials are summarized.
Abstract: Nowadays a wide variety of synthesis techniques are utilized to produce nanoporous materials. In this review, we summarize the general principles of templated synthesis using various types of templ...

494 citations

Journal ArticleDOI
TL;DR: The synergy between catalytic propulsion and mesoporous silica nanoparticles (MSNPs) for the design of Janus nanomotors as active cargo delivery systems with sizes <100 nm (40, 65, and 90 nm) is reported.
Abstract: We report on the synergy between catalytic propulsion and mesoporous silica nanoparticles (MSNPs) for the design of Janus nanomotors as active cargo delivery systems with sizes <100 nm (40, 65, and 90 nm). The Janus asymmetry of the nanomotors is given by electron beam (e-beam) deposition of a very thin platinum (2 nm) layer on MSNPs. The chemically powered Janus nanomotors present active diffusion at low H2O2 fuel concentration (i.e., <3 wt %). Their apparent diffusion coefficient is enhanced up to 100% compared to their Brownian motion. Due to their mesoporous architecture and small dimensions, they can load cargo molecules in large quantity and serve as active nanocarriers for directed cargo delivery on a chip.

327 citations

Journal ArticleDOI
Fuli Zhao1, Dan Yao1, Ruiwei Guo1, Liandong Deng1, Anjie Dong1, Jianhua Zhang1 
TL;DR: This review comprehensively summarized recent advances in the design, synthesis, functionalization and application of nanocomposite hydrogels with enhanced mechanical, biological and physicochemical properties.
Abstract: Due to their unique structures and properties, three-dimensional hydrogels and nanostructured particles have been widely studied and shown a very high potential for medical, therapeutic and diagnostic applications. However, hydrogels and nanoparticulate systems have respective disadvantages that limit their widespread applications. Recently, the incorporation of nanostructured fillers into hydrogels has been developed as an innovative means for the creation of novel materials with diverse functionality in order to meet new challenges. In this review, the fundamentals of hydrogels and nanoparticles (NPs) were briefly discussed, and then we comprehensively summarized recent advances in the design, synthesis, functionalization and application of nanocomposite hydrogels with enhanced mechanical, biological and physicochemical properties. Moreover, the current challenges and future opportunities for the use of these promising materials in the biomedical sector, especially the nanocomposite hydrogels produced from hydrogels and polymeric NPs, are discussed.

272 citations