小島 隆

Strontium titanate (SrTiO3) particles are expected to be applied to various catalysts, and many kinds of synthesis procedures of SrTiO3 particles with a high specific surface area have been proposed. This study investigates a synthesis procedure of preparing SrTiO3 particles with a high specific surface area by minimizing the crystallization temperature to the least possible value. The SrTiO3 particles are prepared by maintaining spherical hydrous titania particles with smooth or porous surfaces in highly concentrated strontium hydroxide solutions at <= 120 degrees C. When porous hydrous titania particles are used as the raw material and the Sr/Ti ratio in the reaction solution is set at 10, spherical protrusions of SrTiO3 develop on the surface of the original hydrous titania, even at a low temperature (25 degrees C). Single-phase SrTiO3 particles with spherical protrusions composed of very fine crystallites are obtained by treatment at 40 degrees C for 24 h. These particles have a high BET specific surface area of 237m(2) g(-1). The process developed herein is eco-friendly and effective for fabricating various perovskite-type compounds with a high specific surface area. (C) 2021 The Ceramic Society of Japan. All rights reserved.

Calcia-stabilized zirconia (CSZ) samples were prepared under hydrothermal (HT) conditions for an efficient catalyst in the vapor-phase dehydration of 1,4-butanediol (1,4-BDO). Preparative aspects of CSZ for the efficient catalyst were discussed. Ammonia aqueous media in the HT aging were effective for high crystallinity of tetragonal/cubic CSZ with high specific surface area, which resulted in high catalytic performance in the dehydration of 1,4-BDO while not all Ca in the solution was included in ZrO2 precipitates in the ammonia media. Although almost all Ca was included in ZrO2 in the strong basic KOH/NaOH aqueous solution, the CSZ samples aged in the strong basic media, which were composed of mainly CaZrO3 crystallite, were readily sintered resulting in poor catalytic activity. Sr cations as well as Ca cations were included in ZrO2 to stabilize cubic ZrO2, while small amounts of Mg and Ba cations were included in ZrO2 not to stabilize the cubic ZrO2 structure. Among the alkaline earth cations, Ca was the most effective in enhancement of catalytic activity in the dehydration of 1,4-BDO. CSZ with a Ca content of 9.4 mol% calcined at 900 °C exhibited the highest 3-buten-1-ol selectivity of 89.2 % at a 1,4-BDO conversion of 54.7 % at 325 °C.

An inverse opal structure was created using artificial melanin particles composed of a polystyrene core and a polydopamine shell as the template. The melanin-mimicking polydopamine that remained inside the inverse opal structure effectively absorbed multiple scattered light, producing bright structural color that was reversibly changed by solvent penetration.

Melanin influences light reflection and absorption and is known to be one of the elements producing structural color, such as that in the feathers of birds. In this study, we used polydopamine (PDA), an artificial melanin, as a light-absorbing material and examined in detail the effect of its composite method on the structural color. The following two composite methods were investigated using cerium(IV) oxide (CeO2) particles as a core particle: binary coassembly of CeO2 and PDA particles and unary assembly of CeO2@PDA core-shell particles. While both methods dramatically improved the visibility of the structural color by suppressing the scattered light due to the light absorption capability of the PDA, there was a difference in the particle arrangement, angle dependence of the structural color, and color tone change. By selecting the PDA composite method, the guidelines for providing high visibility and the desired structural color were presented.

© 2020 International Solar Energy Society A high-voltage type solar cell consisting of a TiO2 photocatalyst on the anode, an Ag–TiO2 photocatalyst on the cathode, and the water/O2 redox system is enabled and optimized by controlling the Ag size (~4 nm) and core–shell structure at the proximity of the indium tin oxide cathode, the photocatalyst film thickness (3.1 ± 0.3 μm), and the configuration of photoelectrodes in the solar cell (SC). The active sites for O2 photoreduction were Ag0 in situ formed on cathode irradiated by UV–visible light as evidenced by Ag K-edge extended X-ray absorption fine structure. Ag–Ag coordination number increased from 1.6 under aqueous HCl electrolyte to 9.6–11 under the conditions of SC tests, suggesting homogeneous Ag size distribution and maximized Ag0 active sites. The effective Ag0 shell was present only under the irradiation of UV–visible light; Ag0 sites were transformed into Ag2O sites when the light was turned off. By the optimization of Ag content and Ag–TiO2 film thickness on photocathode and light irradiation configuration from photocatalyst/electrode side on anode/cathode, an open-circuit voltage of 1.55 V exceeding most of the SC reported so far. Furthermore, cell power of 18.7 µW cm−2 was also achieved.

© 2019 Elsevier B.V. Supported MnOx nanocluster was prepared by PVP-stabilized Mn colloid as a precursor. Obtained catalysts were applied for 1-phenylethanol oxidation to produce acetophenone. Consequently, prepared catalysts were active for the oxidation of 1-phenylethanol using molecular oxygen without any additives such as base reagents. XAFS and TEM measurements revealed that the valence of manganese oxide and cluster size of manganese oxide on prepared catalysts can be controlled. In addition, the chemical state of Mn species varied with the loading amount of Mn.

© 2019 Elsevier Ltd and Techna Group S.r.l. Uniform, micron-sized SrTiO3 particles do not tend to aggregate, and the low surface area of larger particles can be improved by incorporating porous structures, thus offering superior performance for a range of applications. In this study, submicron-to micron-sized SrTiO3 particles were prepared using hot water or hydrothermal conversion of spherical hydrous titania (TiO2·nH2O) and porous hydrous titania. When spherical hydrous titania particles were employed as the starting material, spherical SrTiO3 particles of hydrous titania were obtained via treatment at 120 °C for 24 h. Similarly, the use of porous hydrous titania particles treated at 90 °C for 48 h resulted in spherical porous SrTiO3 particles with macropores of porous hydrous titania. These porous SrTiO3 particles have a specific surface area of ~115 m2/g, which is one of the largest among micron-sized SrTiO3 particles, thereby making them suitable for use as catalysts or photocatalysts.

Copyright © 2018 American Chemical Society. Pd-perovskite (Pd-STO, STO = SrTiO 3 ) was synthesized by a relatively low-temperature (373 K) hydrothermal method without calcination. The morphology of the Pd-STO could be controlled by adjusting the H 2 O/NH 3 ratio during the fabrication of the amorphous titania. The Pd-STO catalyst showed better durability for Suzuki couplings than did Pd-impregnated catalysts on conventional supports.

We successfully prepared Pd-containing perovskite strontium titanate (Pd-STO) by a relatively low-temperature hydrothermal method (i.e., 373 K) without posterior calcination. The particle size and porosity of the STO perovskite could be tuned by changing the molar ratio of H2O/NH3 (e.g., 5.0, 12.5 and 25.0) during the preparation of the amorphous titania sources. The mesoporous contained Pd-STO(12.5) showed superior catalytic performance compared to that of the other Pd-STO(x) (x = H2O/NH3) perovskites for alcohol oxidation with molecular oxygen. Both the refluxing of the non-polar solvents and addition of molecular sieves enhanced the reaction yield significantly. The Pd-incorporated perovskite (Pd-STO) showed better recyclability compared with that of the impregnated perovskite (imp-Pd/STO).

Sol of layered titanate particles was obtained by stirring mixed solution of ethylene glycol and TiCl3 aq. at room temperature for 24 h and gel was obtained by dialysis of the obtained sol. According to XRD measurement, the obtained gel consisted of anatase TiO2 nanoparticles. Synthesis of Nb-doped anatase TiO2 gel was also examined. Stirring the mixture of ethylene glycol, TiCl3 aq., and ethanol solution of NbCl5 also formed the layered titanate sol and Nb-doped anatase TiO2 gel was obtained by dialysis of the sol. Furthermore, heat treatment of the obtained gel was carried out by soaking it in H2O at 368 K for 24 h. This procedure greatly improved degree of crystallization of the anatase gel. In order to examine the effect of Nb doping on electrical property of the obtained anatase TiO2 gel, UV-VIS-NIR reflectance spectra of the obtained Nb-doped TiO2 particles were measured. When the doped amount of Nb ions increased, the decrease of reflectance of the powders occurred in NIR wavelength range. This result indicated that conduction electron density occurred by Nb doping. Accordingly, dialysis process of the sol obtained by stirring metal chloride solution in air at room temperature enabled to obtain Nb-doped anatase TiO2 gel.

海水中でのストロンチウム（Sr）の吸着容量を高めるために，ペルオキソチタン錯体アニオンをジメチルアミノプロピルアクリルアミド（DMAPAA）グラフト重合繊維に吸着固定した．その後，オルトケイ酸ナトリウムとの反応によってチタンケイ酸ナトリウムに転化・析出させた．得られた繊維を，液繊維比100 mL/gで人工海水に浸漬したとき，Sr除去率およびCaに対するSrの選択係数は，それぞれ83 ％および4.3であった．これらの除去率および選択係数の値はチタン酸ナトリウム担持繊維のそれに比較して，それぞれ1.1および2倍であった．

<p>ストロンチウム（Sr）吸着材を構成するチタン酸ナトリウム（ST）の前駆体であるペルオキソチタン錯体（POTC）アニオンをジメチルアミノエチルメタクリレート重合繊維へ繰り返して吸着固定し，これをNaOHと反応させSTに転化・析出することによって，Srイオンを海水中で，高容量で捕集するSr吸着繊維を作製した。10回の繰り返し吸着固定後にNaOHとの反応によって得られる吸着繊維のST担持率は1回の担持によるST担持率18％の1.6倍（29％）に増加した。10回の担持で，人工海水中でのSr飽和吸着容量も1.5倍（2.9 mg-Sr/g）に増えた。</p>

Abstract: Gluconate modified layered titanate particles and their sol were prepared using titanium tetraisopropoxide (TIP) and gluconic acid aqueous solution. A mixture of ethylene glycol solution of TIP and gluconic acid aqueous solution was heated at 368 K for 24 h to obtain sol. The particles, which had a layered structure, were dispersed stably in the sol. Furthermore, dialysis of the sol with H2O formed sol with stable dispersion of the layered titanate particles in H2O. Fourier -Transform Infrared Spectroscopy (FT-IR) and Raman spectra of the obtained particles indicated that they were layered titanate particles with gluconic acid on the surface, that is, the particles were gluconate modified layered titanate. Drying the sol spontaneously formed plate morphology. The aggregated structure of the layered titanate particles swelled with H2O and formed gel. The addition of H2O to the aggregated structure finally lead to a stable dispersion of the layered titanate particles in H2O, when the weight ratio of H2O to the layered titanate was higher than 15. According to SEM observation of the freeze dried gels, the layered titanate particles had also plate morphology with a high aspect ratio and lamellar structure. Furthermore, when glycerol was dissolved into the sol of the layered titanate particles and the sol was heated to evaporate H2O, alternately integrated layered structures were obtained and they showed structural color, which depended on the weight ratio of the layered titanate particles and glycerol. Graphical abstract: UV–VIS transmittance spectra and photographs of the complex gel plate between the gluconate modified layered titanate particles and glycerol. The structural color depends on the weight ratio of (layered titanate sol/glycerol).

The reaction pressure in the photocatalytic conversion of CO2 into fuels is optimized between 0 and 0.80 MPa under CO2 and moisture. The higher reactivity of water than H-2 was observed at higher pressure and the reason was clarified using several similar to 10 mu m-thick semiconductor-based photocatalysts. The best Pd/TiO2 photocatalyst produces methane with a reaction order of 0.39. The sum of independent total formation rates of C-containing compounds under UV and visible light does not account for that under UV-visible light, demonstrating synergetic reaction mechanism on Pd for CO2 reduction by excited electrons via surface plasmon resonance and on TiO2 for water oxidation. Active metallic Pd and 0 vacancy sites due to O-2 formation from H2O are confirmed by in situ monitoring of EXAFS [N(Pd-Pd) = 5.9-6.2; N (Ti-0)= 5.2-3.5] and the decrease of the H-bound and bi/tri-coordinated OH peaks in FTIR. Effective redox-site separation explains the higher reactivity of water than H-2. (C) 2017 Elsevier Inc. All rights reserved.

Ni-Fe alloy catalysts prepared by a simple hydrothermal method and subsequent H-2 treatment exhibited the greatest activity and selectivity for the hydrogenation of biomass-derived furfural to furfuryl alcohol among the examined second metals, such as Al, Ga, In, Co, and Ti. This work reveals that the alloying of Ni and Fe is a key factor in achieving highly selective hydrogenation of the C=O moiety in unsaturated carbonyl substrates. We found that decreasing the temperature of H-2 treatment (i.e. decreasing the crystallite size), e.g. Ni-Fe(2)HT-573 K (TOF = 952 h(-1)), increased the activity compared to that over Ni-Fe(2)HT-673 (TOF = 375 h(-1)) for furfural hydrogenation. This result suggests that a low-coordinated Ni-Fe alloy was imperative for the catalytic cycle. Moreover, the effect of the metal/support interface was critical; despite the high catalytic performance of Ni-Fe/TiO2, Ni-Fe/Al2O3, and Ni-Fe/CeO2, Ni-Fe supported on SiO2, taeniolite, and hydrotalcite catalysts were ineffective. Vibrational studies using FT-IR measurement confirmed that furfural was physically adsorbed on the surface of the Ni-Fe alloy catalyst via an. eta(1)(O) configuration. The synthetic scope of the Ni-Fe catalytic system was very broad; various types of unsaturated carbonyls, such as unsaturated aromatics, unconjugated aliphatics, and a large substituent, were selectively converted into the corresponding unsaturated alcohols.

The addition of Y2O3 into Ni formed a composite catalyst that selectively produced 1,5-pentanediol rather than 1,2-pentanediol in the hydrogenolysis of furfuryl alcohol at 2.0 MPa H-2 and 423 K. Clearly, 1,5-pentanediol was produced over the Ni-0-Y2O3 boundary. This report highlights the properties of Ni-Y2O3, catalytic performance, and reaction route in the synthesis of 1,5-pentanediol from furfuryl alcohol.

Photocatalytic conversion of CO2 into fuels could mitigate global warming and energy shortage simultaneously. In this study, the reaction pressure was optimized for CO2 reduction by H-2. The major products were methane, CO, and methanol, and the observed catalytic activity order was Cu or Pd on TiO2 &gt;&gt; Ag/ZrO2 similar to g-C3N4 &gt; Ag/Zn3Ga-layered double hydroxide similar to BiOCl. Hot/excited electrons due to surface plasmon resonance could be transferred to CO2-derived species and the remaining positive charge could combine with excited electrons in the semiconductor. As the levels of hot/excited electrons became more negative, the catalysts became more active, except for Ag/ZrO2 and Ag/Zn3Ga-LDH, probably due to lower charge separation efficiency for intrinsic semiconductors or hydroxides. The reaction order was controlled by the partial pressure of H-2, demonstrating preferable adsorption of H on Pd. The photoconversion of CO2 into methane was optimum at P-H2 = 0.28 MPa and P-CO2 = 0.12 MPa, but the rates gradually dropped at higher partial pressures due to adsorption of CO2 being hindered by H. (C) 2016 Elsevier Inc. All rights reserved.

Fuel cells (FCs) and solar cells (SCs) are indispensable devices for a hydrogen energy society. The voltages obtained are less than 1 V per cell for most FCs and SCs. Herein, we use a recently developed SC comprising two photocatalysts. In principle, both TiO2 and BiOCl are photo-excited, and the energy difference between the conduction band (CB) minimum of TiO2 for excited electrons (-0.11 V) and the valence band (VB) maximum of BiOCl for holes (2.64 V) can provide a theoretical electromotive force of 2.75 V. This SC converts light energy into an electromotive force corresponding to the level difference of the two photocatalysts permanently mediated by the redox of water/O-2. The diffusion overpotential of electrons in the photocatalysts (0.23-0.41 V) and the leakage current (0.38 V) are experimentally evaluated. The contact between the TiO2 film and ITO layer is improved by the better dispersion of the TiO2 suspension at a lower pH than that of the isoelectric point. Cyclic voltammetry data suggest the formation of O/Cl vacancy sites during the SC tests and the superiority of the rear orientation of the BiOCl photocatalyst on the cathode and effective photo-oxidation of water over TiO2, whereas impedance measurements suggest a smaller impedance for the tight and uniform TiO2 film in comparison to the porous BiOCl film. Thus, in the optimized configuration of the electrodes (irradiation from the other side of the photocatalyst), the leakage current and the diffusion overpotential in the catalyst layers are effectively suppressed to realize an open-circuit voltage of 1.91 V and cell output of 55.8 mu W per 1.3 cm(2).

Carbon nanomaterials assembled into micrometer-scale configurations are highly useful because of their unique molecular transport and adsorption properties, improved operability, and versatility in industrial/research applications. Here we propose a facile approach to assemble carbon nanotubes (CNTs) into monodisperse microparticles through rapid condensation and accumulation of CNTs in aqueous droplets in a non-equilibrium state. The droplets were generated by means of a microfluidic process or membrane emulsification, using a water-soluble polar organic solvent as the continuous phase. Because water molecules in the droplets were rapidly dissolved into the continuous phase, the CNTs were dramatically condensed and stable microparticles were finally formed. We prepared microparticles using both multi-walled and single-walled CNTs, and the size was controllable in the range of 10-40 mm simply by changing the initial CNT concentration. Interestingly, the morphologies of the particles were not spherical in many cases, and they were controllable by changing the type of the organic solvent and/or using additives in the dispersed phase. Physicochemical characterization suggested good compatibility of the CNT microparticles when used as supports for catalysts, adsorbents, and electrodes.

&lt;p&gt;タンパク質を高容量に吸着するカチオン交換繊維をグラフト重合によって作製するために，モノマー液に溶液とエマルションを使う2種類のグラフト重合法，すなわち放射線前照射溶液および乳化グラフト重合法（以後，溶液および乳化グラフト重合法）を採用し，比較した．市販の6-ナイロン製繊維へグリシジルメタクリレート（GMA）をグラフト重合後，亜硫酸ナトリウムとの反応によってポリGMA鎖のエポキシ基をスルホン酸基へ転化し，カチオン交換繊維を作製した．得られた2種類のカチオン交換繊維を充填したカラムに，リゾチーム溶液（pH 9.0）を空間速度60 h&lt;sup&gt;−1&lt;/sup&gt;で流通させた．GMAグラフト率が81–87%のとき，乳化グラフト重合法によって作製した繊維のカラム体積あたりの10%動的吸着容量は，溶液グラフト重合法によって作製したそれよりも4倍高い値を示した．乳化グラフト重合法によって作製した繊維の周縁部に形成されたグラフト鎖が，タンパク質の高速吸着に寄与すると推察される．&lt;/p&gt;

Porous titania particles were prepared by partial dissolution of hydrous titania and subsequent heat treatment. Uniform and spherical particles of hydrous titania were prepared by hydrolysis of titanium alkoxide at different hydrolysis conditions. The asprepared hydrous titania particles were soaked in ethanol to dissolve the weakly polycondensed part of the particles. As a result, meso-and macroporous structures were formed on the surface of the hydrous titania particles that were prepared by mild hydrolysis. The porous structure was retained even after heat treatment at 400 degrees C while the particles crystallized into the anatase phase. The specific surface area of the porous titania particles prepared by heat treatment of hydrous titania at 400 degrees C for 15 min was 121 m(2)/g. (C) 2016 The Ceramic Society of Japan. All rights reserved.

A layered titanate sol was prepared at room temperature (298 K) using dialysis of a mixed solution of ethylene glycol solution of TiCl3, ammonium carbonate aqueous solution, and hydrogen peroxide. A sol with dispersion of plate-shaped layered titanate nanoparticles was obtained. A stable sol with dispersion of spindle-shaped anatase TiO2 nanoparticles was obtained by heating the sol with dispersion of layered titanate at 368K for 24 h in a closed vessel. The optical transmittance spectrum of the TiO2 thin film obtained by coating the sol with dispersion of anatase nanoparticles and firing at 773 K for 1 h showed no interference of an incident light beam into the TiO2 thin film. Optical characteristics on interference originated from pores among TiO2 primary nanoparticles in the thin film, which caused incoherent scattering of incident light into the thin film. When the sols containing both of the plate-shaped layered titanate nanoparticles and the spindle-shaped anatase nanoparticles were used as the coating solution, the interparticle pore volume was controlled by the volume ratio of the anatase sol in the coating solution. The effects of interference on the optical transmittance spectra of the thin films depended on the interparticle pore volume. (C) 2016 The Ceramic Society of Japan. All rights reserved.

At Tokyo Electric Power Company (TEPCO) Fukushima Daiichi nuclear power plant (NPP), water contaminated with radionuclides such as Cs-137 and Sr-90 has been stored in tanks and seawater-intake area. We have prepared cobalt-ferrocyanide-impregnated fibers via four steps: the grafting of an epoxy-group-containing monomer, the conversion of the epoxy group into positively charged groups, the binding of ferrocyanide ions ([Fe(CN)(6)](4-)), and the precipitation of cobalt ferrocyanide (Co-2[Fe(CN)(6)]) by contact with cobalt ions. However, the impregnation structure of cobalt ferrocyanide microparticles onto the fiber remains unclear. Here, we describe the impregnation structure from the results of rebinding [Fe(CN)(6)](4-) to the cobalt-ferrocyanide-impregnated fiber. The amount of [Fe(CN)(6)](4-) re-bound onto the fiber was found to decrease with increasing amount of Co-2[Fe(CN)(6)] initially impregnated. This suggests that the microparticles of cobalt ferrocyanide become entangled with the grafted polymer chains via multipoint electrostatic interactions.

Optically transparent and stable sols of copper ion doped zinc sulfide (ZnS:Cu) nanoparticles were obtained by heating a mixture of ethylene glycol aqueous solution and sulfide precipitate at 348K for 24 h. The sulfide precipitates containing zinc ions, copper ions and citrate ions were peptized in an aqueous solution of ethylene glycol having a 0.5 molar fraction of [Ethylene glycol]/([H2O]+[Ethylene glycol]). Photoluminescence characteristics and stability of the sols depended on the amount of citrate ions in the aqueous solution which was used for preparing sulfide precipitates. The citrate ions strongly affected the characteristics of the obtained sols with dispersion of the copper ion doped-ZnS nanoparticles. According to TG-DTA curves and N-2 adsorption isotherms of the precipitated sulfides, the citrate ions in the aqueous solution containing zinc ions, copper ions coprecipitated in the sulfide precipitates formed by adding the sodium sulfide aq. The citrate ions played an important role for the peptization and the formation of stable sols. (C) 2015 The Ceramic Society of Japan. All rights reserved.

海水からのストロンチウムの除去のために，放射線グラフト重合とそれに続く化学修飾によって，チタン酸ナトリウム担持繊維を作製した．まず，6-ナイロン繊維にアニオン交換基をもつビニルモノマーであるジメチルアミノプロピルアクリルアミドをグラフト重合し，アニオン交換繊維を作製した．そして，チタンイオン種としてペルオキソチタン錯体アニオンをアニオン交換基に吸着させた後，アルカリ処理することによって，結晶性の高いチタン酸ナトリウムを繊維表面に析出させた．海水中でのストロンチウムに対するチタン酸ナトリウム担持繊維の平衡吸着容量はLangmuir型吸着等温線から1.7 mg/gと算出された．

The facile preparation of nonspherical raspberry-like particles composed of a polystyrene (PSt) core and polydopamine (PDA) nodules was described. Various polymerization parameters influencing the PDA nodules were investigated in detail. It was found that raspberry-like particles were obtained in a 1:1 water/methanol solution in the presence of compounds with carboxylic acid groups, e.g., caffeic acid (CF). The raspberry-like particles obtained were characterized in terms of their size, morphology, and chemical composition using scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared (IR) spectroscopy, elemental analysis, and solid-state nuclear magnetic resonance (NMR) measurements. Finally, the formation mechanism was discussed. Because PDA may be used to cover a variety of particle surfaces, the present method has great potential for fabricating many types of raspberry-like particles. (C) 2014 Elsevier B.V. All rights reserved.