Yoshitake Masuda

National Institute of Advanced Industrial Science and Technology · Inorganic Functional Materials Research Institute

Aroma essential oils contain ingredients that are beneficial to the human body. A gas sensor array is required to monitor the concentration of these essential oil components to regulate their concentration by air conditioning systems. Therefore, we investigated the discrimination ability and concentration measurement accuracy of 14 effective compon...

The sensitivity of the metal–oxide–semiconductor‐type gas sensors has been improved typically using novel metal catalysts, such as Pt, Ru, and Pd. However, the sensing performance could be enhanced by only controlling the nanostructure. Herein, we introduce fabrication methods for ZnO nanobelt by changing the supply rate of hydroxide ions. Hexameth...

CeO2 nanocubes with metastable {100} facets and CeO2 nanooctahedrons with the most stable {111} facets are herein fabricated by controlling the morphology and facets of CeO2 nanoparticles. SnO2 nanosheet-based assembled films coated with these CeO2 nanocubes or CeO2 nanooctahedrons yield {100} CeO2 nanocubes/SnO2 nanosheets and {111} CeO2 nanooctah...

Atomic defects can enhance catalytic efficiency by providing coordinatively unsaturated sites in the crystal structure of metal oxides. It allows facile chemical reactions because the sites can react with other molecules with relatively lower energy. Therefore, atomic defect engineering can be a cost‐effective strategy to replace novel metal cataly...

Highly Sensitive and Selective Gas Sensors In article number 2202442, Chunyan Li, Pil Gyu Choi, and Yoshitake Masuda introduce an in‐situ fabrication of Ni(OH)2 nanosheets on gas sensor chips via a facile solvothermal process combined with post‐synthetic MnO2 on its surface for modification. The NiO/MnO2@NiO gas sensors have excellent sensitivity a...

Mental stress management has become significantly important because excessive and sustained mental stress can damage human health. In recent years, various biomarkers associated with mental stress have been identified. One such biomarker is allyl mercaptan. A nanosheet-type tin oxide exhibited high gas selectivity for allyl mercaptan; thus, in this...

Control of nanomaterial morphology has been investigated to utilize for the desired application. 1D nanomaterials are ideal for various applications because of their excellent carrier transportability and huge specific surface area. Due to their advantages, various methods have been developed to grow in a specific direction. Herein, we introduced a...

NiO nanosheets are synthesized in situ on gas sensor chips using a facile solvothermal method. These NiO nanosheets are then used as gas sensors to analyze allyl mercaptan (AM) gas, an exhaled biomarker of psychological stress. Additionally, MnO2 nanosheets are synthesized onto the surfaces of the NiO nanosheets to enhance the gas‐sensing performan...

This paper discusses the direct fabrication of ultrathin Ni(OH)2 nanosheets on substrates via a facile solvothermal process, which is free from the use of additional, surfactants. The precursor is converted into porous NiO nanosheets via heat treatment., The thickness and morphology of the nanosheets is controlled by manipulating the, ethanol conte...

This study analyzed temporal variation of the composition of volatile organic compounds (VOCs) at different diffusion time of gaseous phase of aroma compounds of four essential oils, lavender, tea tree, eucalyptus, and melissa. GC/MS methodology with the trace gas sampling by a thermal desorption tube is used to quantitatively determine the concent...

Atomic defects, such as steps and kinks, can promote the efficiency of chemical reactions. These defects provide coordinatively unsaturated sites (CUS) in metal oxides and the CUS reacts with other...

Gas sensors are advantageous as they can be applied in various fields. The metal-oxide semiconductor gas sensor is the most widely used gas sensor. In this study, the gas-sensing properties of high-purity semiconducting single-walled carbon nanotubes (SWCNTs), which behave as p-type semiconductors, are analyzed at temperatures of 50, 100, and 200 °...

The development of a gas sensor for ppb‐level detection has been required for the industrial and medical fields. Exposed facet control is an effective way to improve gas sensing performance without novel metal catalysts. Herein, we investigated the change in gas sensitivity of ZnO nanostructures depending on the exposed surface. ZnO‐rod and ZnO‐whi...

The morphology of ZnO nanostructures was controlled by the type of electrodes used, without chemical additives in the solution plasma process. Nanorod and nanosheet-type ZnO were synthesized using Zn and W electrodes, respectively. In the solution plasma process, the ZnO nanostructure can be fabricated because of the unique reaction between ions an...

ZnO nano-bullets were synthesized using solution plasma from only Zn electrode in water without any chemical agents. In this sustainable synthesis system, the rapid quenching reaction at the interface between the plasma/liquid phases facilitates the fast formation of nano-sized materials. The coil-to-pin type electrode geometry, which overcomes the...

Herein, the authors successfully synthesize diamond- and square-type Cu-metal–organic frameworks (MOFs) and then convert them to highly porous CuO nanostructures with maintaining their morphology. Both the CuO-diamond (CuO-D) and CuO-square (CuO-S) gas sensors can detect a tiny concentration of acetone gas up to 50 ppb. However, the gas sensitivity...

We investigate selective detection of target volatile organic compounds (VOCs) as unpleasant odor substances in the presence of interference VOCs from car interiors. We selected four unpleasant odor substances as target gases, such as age-related body odors and fungi, and two interference VOC substances, such as the main olfactory components from c...

Resistive-type semiconductor-based gas sensors were fabricated for the detection of methyl mercaptan and hydrogen sulfide. To fabricate these sensors, V2O5/WO3/TiO2 (VWT) particles were deposited on interdigitated Pt electrodes. The vanadium oxide content of the utilized VWT was 1.5, 3, or 10 wt.%. The structural properties of the VWT particles wer...

The development of a facile gas sensor for the ppb-level detection of acetone is required for realizing health diagnosis systems that utilize human breath. Controlling the crystal facet of a nanomaterial is an effective strategy to fabricate a high-response gas sensor without a novel metal catalyst. Herein, we successfully synthesized a SnO2 nanosh...

The Na0.5Co0.9Cu0.1O2 thick film with the same thermoelectric performance as a Na0.5CoO2 bulk was formed on an alumina substrate by the screen-printing process. The power factor exceeded 0.3 mW/K2m, with the resistivity of 3.8 mΩcm and the thermopower of 108 μV/K. The thick film without any cracks strongly adhered to the substrate. The high-quality...

We investigated the selective detection of target volatile organic compounds (VOCs) which are age-related body odors (namely, 2-nonenal, pelargonic acid, and diacetyl) and a fungal odor (namely, acetic acid) in the presence of interference VOCs from car interiors (namely, n-decane, and butyl acetate). We used eight semiconductive gas sensors as a s...

We reported the successful formation of nanopores within core-shell type metal oxide particles using the shell layer as a template. Using the polyol method, core-shell type metal oxide particles such as cerium oxide, zinc oxide, and cobalt oxide with primary particles of ~10 nm and secondary particle sizes between 20 and 300 nm were prepared, where...

We investigate selective detection of target volatile organic compounds (VOCs) as unpleasant odor substances in the presence of interference VOCs from car interiors. We selected four unpleasant odor substances as target gases, such as age-related body odors and fungi, and two interference VOC substances, such as the main olfactory components from c...

Driven by the emergence of colloidal semiconductor quantum dots (QDs) of tunable emission wavelengths, characteristic of exciton absorption peaks, outstanding photostability, and solution processability in device fabrication has become a key tool in the development of nanomedicine and optoelectronics. Diamond cubic crystalline silicon (Si) QDs, of...

Nanopores were successfully formed in cobalt oxide particles by carrying out sintering to remove the shell of core-shell type cobalt oxide particles comprised of a cobalt oxide core and a polyvinylpyrrolidone (PVP) shell. During synthesis of the cobalt oxide partices, PVP-covered Pt or Pd particles were added to achieve metal loading on the nanopor...

A family of mixed LiNixCo(1-x)VO4 (x = 0.2, 0.8) cathode materials has been synthesized using the sol–gel method. The thermal behavior of the materials has been examined by thermogravimetric (TG) analysis. The Rietveld refinement of powder X-ray diffraction showed the structure with \( Fd\overline{3}m \) (227) space group. Surface analysis was perf...

The proposed work reports that ZnO nanoflowers were grown on fluorine-doped tin oxide (FTO) substrates via a solution process at low temperature. The high purity and well-crystalline behavior of ZnO nanoflowers were established by X-ray diffraction. The morphological characteristics of ZnO nanoflowers were clearly revealed that the grown flower str...

In this work, Vertically oriented WO3 nanoflakes array films was synthesised via the template free facile electrodeposition method at room temperature. WO3 nanoflakes arrays was adopted as an effective cathode electrode material in the electrochemical devices structure. The WO3 material exhibits superior electrochromic performance shows a larger op...

This paper reports a facile low-temperature hydrothermal process to grow highly porous ZnO nanosheets, self-assembled in rosette like morphology, over the transparent indium tin oxide (ITO) glass substrate for dye-sensitized solar cell application. The prepared porous nanosheets were examined in detail using several techniques to understand the mor...

The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163 •. Silver is further dep...

A sensor has been developed for detecting 1-nonanal gas present in the breath of lung cancer patients by combining SnO2 nanosheets with SnO2 nanoparticles and noble metal catalysts. A significant change in the electrical resistance of this sensor was observed with increasing 1-nonanal gas concentration; the resistance decreased by a factor of 1.12...

A notably high-capacity antibody adsorbent was demonstrated using dispersed gold nanoparticles immobilised on a mesoporous silica sheet. The mesoporous silica sheet (MPS sheet) was prepared via a dual-templating method using tetraethoxysilane and 3-aminopropyltriethoxysilane as the silica framework materials. Gold nanoparticles were loaded on the a...

Many biosensors have been developed and used in recent years, and to enhance the sensitivity and stability of enzyme biosensors, immobilization of the enzymes on material surfaces is a necessary and important step. Therefore, there has been considerable interest in understanding how material interfaces affect enzyme adsorption. In this study, the i...

A novel design of white light emitting diodes (WLEDs) emerges to meet the growing global demand for resource sustainability while preserving health and environment. To achieve this goal, a facile method is developed for the chemical synthesis of a luminescent silicon nanocrystal (ncSi) with a large Stokes shift between absorption and emission. The...

Dense tin oxide films were successfully fabricated in an aqueous solution. The pH of the solutions was controlled to pH 1.3 by addition of HCl. Precise control of solution condition and crystal growth allowed us to obtain dense tin oxide films. Concave-convex surface of fluorine-doped tin oxide (PTO) substrates was entirely-covered with the continu...

SnO2 nanosheet–assembled graded continuous films were successfully fabricated in aqueous solutions containing SnF2 of 250 mM at 90°C. Thickness reached 1200 nm after immersion for 24 h. The nanosheets were 100–500 nm in in-plane sheet size and 5–20 nm in thickness. The graded structures were caused by gradual change in supersaturation degree of the...

Anatase TiO2 nanocrystals of 10 nm were formed in aqueous solutions at 90 degrees C for 1 day. The solutions contained ammonium hexafluorotitanate (5 mM) and boric acid (15 mM). The nanocrystals connected each other to form particles of about 100-500 nm. X-ray diffraction, Raman and FT-IR analysis revealed characteristics of the nanocrystals. They...

Crystals of TiO2 grew on substrates in aqueous solutions at 50 degrees C for 180 day. Long term synthesis brought us nano-structured films and information of crystal growth. The films showed 101 diffraction peak of anatase phase. Morphology of the crystals well developed to needle shapes. They stood perpendicular to the substrates. The films had na...

Halogen- and acid-free aqueous solutions were developed to synthesize TiO2 nanocrystal coatings and high surface area TiO2 nanocrystal-assembled particles. Fluorine doped tin oxide substrates were covered with TiO2 nanocrystal coatings in the solutions containing titanium(IV) potassium oxalate, 2-hydrate (K2[TiO(C2O4)2] x 2H2O) at 90 degrees C for...

Tin oxide nanostructures were fabricated using a water bath technique. The structures were modified with dye-labeled DNAs for a molecular sensor. Sensing mechanism of the sensor was based on a photoelectric conversion effect. Photoluminescence intensities from the tin oxide nanostructures reached to 16 times larger than that from SnO2:F films. High...

We present the case of a 64-year-old male with painful swelling of the bilateral testes and epididymides, high fever, leukocytosis, and an elevated C-reactive protein (CRP) level. This is the first case report of testicular diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS) immunostained for multiple cytokines and their receptors,...

α-Fe2O3 nanostructures with well-defined morphology: Nanostructured dendrites, nanorods, nanospindles, and nanocubes were successfully synthesized by forced hydrolysis/reflex condensation and hydrothermal methods. The specific surface area and pore size distribution analysis of the different nanostructures prepared in this study confirms that these...

Microporous and mesoporous ZnO nanosheets were successfully synthesized by a low-temperature chemical bath deposition and subsequently thermal decomposition at 250 degrees C without any templates. Nanosheet-shaped zinc hydroxide nitrate (Zn-3(OH)(4)(NO3)(2)) was formed as the precursors at 90 degrees C for 6 days by chemical bath deposition in a cl...

A recently developed "GRAPE(®) technology" provides titanium or titanium alloy implants with spontaneous apatite-forming ability in vitro, which requires properly designed gaps and optimum heat treatment in air. In this study, titanium alloy and commercially pure (cp) titanium substrates were thermally oxidized in air before aligning pairs of speci...

SnO2 films were fabricated on fluorine-doped tin oxide (FTO) substrates in aqueous solutions. The films of about 800 nm in thickness grew in the solutions containing SnF2 of 25 mM at 90 °C for 24 h. They consisted of nanosheets of about 5-10 nm in thickness and about 100-1600 nm in plane size. The films had gradient structure of nanosheets. Smaller...

We have investigated the effect of Fe doping on the structural and electrical properties of the double perovskite oxide Sr2Mg1−xFexMoO6−δ (x = 0, 0.2, 0.5). The structure of the Fe doped compounds is tetragonal, unlike the triclinic undoped compound. The Fe doping favors the reduction of Mo6+ to Mo5+, which plays a vital role in determining the ele...

The main purpose of this article is to examine the surface free cerium oxide (CeO2) nanostructures prepared by different methods. CeO2 nanoparticles and nanorods were prepared by two different methods including precipitation and hydrothermal process. In precipitation process the nanoparticles were prepared at room temperature, while in hydrothermal...

Criteria from the World Health Organization (WHO) are commonly used to diagnose plasma cell myeloma (PCM), but they are complex and require several laboratory parameters. To differentiate reactive plasmacytosis from clonal plasma cell neoplasms, such as PCM, it is important to accurately determine the expression of the cytoplasmic immunoglobulin (c...

X-ray crystallographic analysis revealed that the palladium-catalyzed β-allylation of yohimbine proceeded in a (7S)-selective manner. The crystal structure had an indolenine unit that was generally unstable in air. A stereoselective outcome was obtained when the palladium π-allyl complex approached yohimbine from the less-hindered pro-S side. Howev...

Calcium doped lanthanum cobaltite (La1 − xCaxCoO3) (x = 0, 0.2, 0.4, 0.6, 0.8) with different concentrations has been prepared by modified Pechini type polymerizable method. The X-ray diffraction pattern of the calcium doped samples shows the formation of perovskite material in cubic structure. Scanning electron and transmission electron microscopi...

The lithium cobalt vanadate (LiCoVO4) cathode material has been synthesized by sol–gel method. Rietveld refinement analysis of powder X-ray diffraction pattern confirmed that the prepared LiCoVO4 crystalline sample had a cubic structure and showed no evidence of secondary phase peaks. FESEM and TEM images of LiCoVO4 identified that the particle ran...

Anticorrosive molybdate films composed mainly of Mg(OH)2, MoO2, MoO3, and MgF2 were formed on magnesium alloy AZ31 by chemical conversion. The film had relatively compact surfaces and a thickness of approximately 800 nm. The XPS studies revealed that the film contained Mg, Al, Mo, O, P, S, and F elements. The corrosion resistant performances of the...

The optical properties of self-twin ZnO nanoarrays assemblies giving a large fraction of polar planes were investigated by the photoluminescence (PL) and a UV-visible spectroscopy. Self-twin ZnO nanoarrays assemblies exhibited strong green–yellow band emission in wavelength of 510–580 nm and a bandgap energy of 3.15 eV. The intensity ratio of ultra...

Hydroxyapatite (HAp) nanocrystals with different levels of fluorine substitution (P/F = 0, 6, 4 and 2) on the OH sites were produced via hydrothermal method. The fluorine substitution was found to alter the morphology of crystals appreciably. The aspect ratio and the crystallinity of HAp crystals increased with increasing fluorine substitution. The...

α-Fe2O3 nanostructures with well-defined morphology: nanostructured dendrites, nanorods, nanospindles, and nanocubes were successfully synthesized by forced hydrolysis/reflex condensation and hydrothermal methods. The specific surface area and pore size distribution analysis of the different nanostructures prepared in this study confirms that these...

In this paper, CeO2 and cobalt-doped CeO2 nanorods synthesized by surfactant free co-precipitation method. The microstructures of the synthesized products were characterized by XRD, FESEM and TEM. The structural properties of the grown nanorods have been investigated using electron diffraction and X-ray diffraction. High resolution transmission ele...

It is revealed that rigorous control of the size and surface of germanium nanoparticles allows fine color tuning of efficient fluorescence emission in the visible region. The spectral line widths of each emission were very narrow (<500 meV). Furthermore, the absolute fluorescence quantum yields of each emission were estimated to be 4-15%, which are...

Characteristic tin oxide films were formed on transparent conductive substrates in aqueous solutions. Surface of the films consisted of ellipse‐shaped particles. Particle size in longer or shorter direction was about 300–400 or 200 nm, respectively. In contrast, middle and bottom area of the films were dense structures. Thickness was about 1150 nm....

Nucleation and crystal growth of tin oxide were realized in aqueous solutions. Nano-sheet structures grew in the solutions containing SnF2 at 90 °C to develop in-plane size and thickness gradually. Their color, size, morphology, crystal structure and N2 adsorption property varied with progress of crystal growth. Color of powder changed from white t...

SnO2 nano-sheet assemblies were prepared in aqueous solutions containing SnF2 at 90 °C for 30 min. A transmission electron microscope and a field emission scanning electron microscope observation revealed that they were assembly of nano-sheets of about 50-100nm in size and 5-10nm thickness. Electron diffraction patterns from the nano-sheets were as...

The lithium nickel vanadate (LiNiVO4) cathode material has been synthesized by using sol-gel method. The thermal behavior of the material has been examined by thermogravimetric and differential thermal analysis (TG/DTA). The structure of LiNiVO4 compound has been studied by the Rietveld refined x-ray diffraction (XRD) technique. The Brunauer–Emmett...

Nanocrystal assembled SnO2 particles were synthesized in aqueous solutions. The particles showed high BET surface area of 276 m2/g. It was much higher than that of our previous studies. BJH analyses indicated that the particles had pores of about 2–5 nm. The particles included two kinds of morphologies. The first particles were about 300–1000 nm in...

The article deals with the effect of sonication on ionic conductivity of cerium fluoride. Cerium fluoride nanoparticles have been prepared by simple precipitation method from aqueous solution with sonication assistance. The structural and morphology of the nanoparticles prepared have been studied using X-ray Diffraction (XRD) and Field Emission Sca...

Indium oxide cubic crystals were prepared by using hexamethylenetetramine and indium chloride without the addition of any structure directing agents. The chemical route followed in the present work was a modified hydrothermal synthesis. The average crystallite size of the prepared cubes was found to be 40 nm. A blue emission at 418 nm was observed...

Tin oxide nanosheets were crystallized on transparent conductive oxide substrates of fluorine-doped tin oxide in aqueous solutions. The nanosheets had chemical ratio of Sn:O:F = 1:1.85:0.076, suggesting fluorine doping into SnO(2). They were hydrophobic surfaces with contact angle of 140°. They were converted to hydrophilic surfaces with contact an...

Liquid phase morphology control of ZnO crystals was realized with simple aqueous solution system. ZnO nanowires were successfully fabricated at 50∘C. They were over 50 μm in length and about 100 nm in width. Aspect ratio was estimated to be over 500. They had no branches and were obtained without aggregations. Curved nano-wires clearly indicated hi...

The lithium manganese vanadate (LiMnVO4) cathode material was synthesized by using sol–gel method. The thermal behavior of the material has been examined by thermogravimetric and differential thermal analysis. The structure of LiMnVO4 compound was studied by the Rietveld refined X-ray diffraction technique. Raman spectra showed that the local envir...

CeO2 thin films with hexagonal-shaped pores were successfully prepared by a facile electrodeposition at room temperature combined with an etching process. By using electrodeposited ZnO nanorods as a soft template, the morphology, and microstructure of the CeO2 could be controlled. TEM observation indicated that as-prepared CeO2 film is composed of...

Bunch-shaped ZnO nanowires film was successfully fabricated by the forced-hydrolysis-initiated-nucleation of anhydrous zinc acetate in an aqueous solution of zinc acetate and sodium hydroxide at low temperature. X-ray diffraction and a field emission scanning electron microscope clarified their formation mechanism and morphology development. The mo...

In this study, undoped and yttrium (Y) doped nanocrystalline hydroxyapatite crystals were synthesized by the hydrothermal method at 180°C for 24h. Highly ordered and oriented hydroxyapatite (HAp) nanorods were prepared by yttrium doping and their nanostructure and physical properties were compared with those of undoped HAp rods. FESEM images showed...

Using three primary alcohols (methanol, ethanol and propanaol) as solvent Indium oxide nanoparticles were prepared. Interestingly, the nanoparticles prepared using the three alcoholic solvents showed different morphologies. Even though the formed particles showed a cube-like structure, different sizes in the morphology have been observed in room te...

An asymmetric silica membrane supported on a porous alumina tube substrate was prepared by dip-coating and then surface modification multistage assembly synthesis. The mesoporous silica membrane was repeatedly modified with hexamethyldisilazane after dip-coating in silica sol solution. The separation layer of the silica membrane had an average thic...