Publications by authors named "Dai Mochizuki"

Magnéli-phase TiO, known for its high electrical conductivity and corrosion resistance, is typically prepared by hydrogen reduction at high temperatures (∼1000 °C), leading to large particles. Nanosized TiO have been explored for application toward high specific surface area electrode materials and electrocatalyst supports; nonetheless, the particle size of TiO is still insufficient for utilization as a support. In this study, we have pursued a novel synthetic approach for nanosized TiO platelets with a length of 10-80 nm and thickness of 3-10 nm even under high-temperature conditions.

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Microwave irradiation has great potential to control chemical reactions remotely, particularly reactions that involve electron transfer. In this study, we found that the reduction reaction of bipyridine derivatives on metal nickel particles was accelerated or decelerated by 2.45 GHz microwaves without an alteration of the reaction temperature.

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To imitate the precisely ordered structure of the photoantennas and electron mediators in the natural photosynthesis system, we have constructed the Ru(bpy)-intercalated alternate-layered structure of titanate nanosheets and tungstate nanosheets via thiol-ene click reaction. Before nanosheet stacking, Pt(terpy) was immobilized at the edge of the titanate nanosheets. The visible-light-induced vectorial Z-scheme electron transfer reaction from the valence band of tungstate to the conduction band of titanate via the photoexcited Ru(bpy) was demonstrated by the following two evidences: (1) From the results of the fluorescence decay of Ru(bpy), the rate of the forward electron transfer from the photoexcited Ru(bpy) to the conduction band of titanate was estimated as 1.

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In low dimensional cesium silicate LDS-1 (monoclinic phase of CsHSi2O5), anomalous infrared absorption bands observed at 93, 155, 1210, and 1220 cm(-1) are assigned to the vibrational mode of protons, which contribute to the strong hydrogen bonding between terminal oxygen atoms of silicate chain (O-O distance = 2.45 Å). The integrated absorbance (oscillator strength) for those modes is drastically enhanced at low temperatures.

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Article Synopsis
  • The efficiency of photoenergy conversion systems relies on the rate of electron transfer, which can be influenced by energy gaps, geometries, or environmental factors.
  • A novel approach demonstrates that applying a microwave field can increase the electron transfer rate without altering the system's geometries or materials.
  • The study shows that microwave irradiation shortens the emission lifetimes of CdS quantum dots in bipyridinium solutions, indicating enhanced electron transfer and paving the way for improved photocatalytic reactions.
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Visible-light-induced electron transfer from a tungstate to a titanate layer was demonstrated to be mediated by excited rhodamine B (RhB) intercalated by ion exchange between the two layers. The distance of only 1 nm between the layers provides a large contact area that enables the efficient mediation of electron transfer by RhB.

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Microwave irradiation efficiently heats up the microwave-inert materials in the range of applied frequencies when two microwave-inert materials are brought into contact in the layered configuration. This heating is applied for annealing TiO2 nanoporous films for dye-sensitized solar cells achieving a one order of magnitude more rapid annealing process for comparable performances.

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The accurate and high-resolution measurement of surface pressure is achieved by a pressure/ temperature-sensitive composite paint (bi-PSP), whereas the pressure-sensitive dye photodegraded the temperature sensitive dye in close arrangement of both dyes. In the present study, an attempt was made to synthesize a homogeneous bi-PSP membrane without light-induced degradation of the dye using mesoporous silica. Mesoporous silica as a molecular sieve was the separation of pressure- and temperature-sensitive dyes.

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Air-stable bimetallic Cu-Ag nanoparticles in the range of 12-30 nm have been synthesized at gram scale by a facile alcohol reduction in the absence of surfactants with the assistance of microwave irradiation. The synthesized nanoparticles were analyzed by x-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning TEM, ultraviolet-visible spectroscopy, x-ray photoelectron spectroscopy and thermogravimetry (TG). The stability of the bimetallic nanoparticles against oxidation was examined by TG and in situ temperature-programmed XRD analyses in the atmosphere.

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Mesoporous silica with squared one-dimensional channels (KSW-2-type mesoporous silica), possessing a molecularly ordered framework arising from a starting layered polysilicate kanemite, was obtained through silylation of a surfactant (hexadecyltrimethylammonium, C16TMA)-containing mesostructured precursor with octoxytrichlorosilane (C8H17OSiCl3) and octylmethyldichlorosilane (C8H17(CH3)SiCl2). The presence of the molecular ordering in the silicate framework was confirmed by XRD and TEM. Octoxy groups grafted on KSW-2 can be eliminated by subsequent hydrolysis under very mild condition, and pure mesoporous silica was obtained with the retention of the kanemite-based framework.

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Poly(oxyethylene) alkyl ether (CnEOm) is intercalated into the interlayer space of a layered silicate kanemite by using layered hexadecyltrimethylammonium (C16TMA) intercalated kanemite (C16TMA-kanemite) as the intermediate. C16TMA-kanemite was treated with an aqueous solution of C16EO10, and the intercalation of C16EO10 was confirmed by the slight increase in the basal spacing (from 2.92 to 3.

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A novel methodology for constructing molecularly ordered silica nanostructures with two-dimensional (2-D) and three-dimensional (3-D) networks has been developed by using a stepwise process involving silylation of a layered silicate octosilicate with alkoxytrichlorosilanes [ROSiCl(3), R = alkyl] and subsequent reaction within the interlayer spaces. Alkoxytrichlorosilanes react almost completely with octosilicate, bridging two closest Si-OH (or -O(-)) sites on the silicate layers, to form new five-membered rings. The unreacted functional groups, Si-Cl and Si-OR, are readily hydrolyzed by the posttreatment with a water/dimethyl sulfoxide (DMSO) or water/acetone mixture, leading to the formation of two types of silicate structures.

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Dialkoxydichlorosilanes ((RO)2SiCl2, R = alkyl) react almost completely with interlayer silanol groups in a layered silicate octosilicate to create a new crystalline silicate structure consisting of new five-membered rings arranged regularly on both sides of the silicate layers. The introduction of dialkoxysilyl groups to the interlamellar region of layered silicates with regular reaction sites provides a new methodology for the design and construction of novel crystalline silicate frameworks by a soft chemical route.

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