Yoji Kobayashi

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Iridium oxide nanoparticles stabilized by a heteroleptic ruthenium tris(bipyridyl) dye were used as sensitizers in photoelectrochemical cells consisting of a nanocrystalline anatase anode and a Pt cathode. The dye coordinated the IrO(2) x nH(2)O nanoparticles through a malonate group and the porous TiO(2) electrode through phosphonate groups. Under visible(More)
The relationship between crystal quality and the properties of indium phosphide nanowires grown on silicon (111) has been studied by transmission electron microscopy, photoluminescence spectroscopy, and photoelectrochemistry. Wires with no defects and with {111} twin boundaries parallel and perpendicular to the growth direction were obtained by metalorganic(More)
Cation-exchangeable d(0) layered perovskites are amenable to intercalation, exfoliation, and a variety of topochemical reactions, but they lack the interesting electronic and magnetic functionalities of mixed-valent perovskites. Conversely, electronically and magnetically interesting layered perovskites lack scope in terms of interlayer chemistry. To bridge(More)
Rechargeable magnesium batteries are poised to be viable candidates for large-scale energy storage devices in smart grid communities and electric vehicles. However, the energy density of previously proposed rechargeable magnesium batteries is low, limited mainly by the cathode materials. Here, we present new design approaches for the cathode in order to(More)
We report the synthesis of a wide range of single-crystal spinel platelets with exposed (111) faces, lateral dimensions in the micrometer range, and thicknesses of 20–50 nm, prepared by soft chemical dehydration of well crystallized layered precursors. This method enables the synthesis of the metastable composition NiCoAlO 4 , which cannot be prepared by(More)
Gold nanoparticles have attracted widespread interest in both materials chemistry and biomedical science because of their special electronic, magnetic, catalytic, and optical properties 1,2 For these applications, it is important to be able to control the size, shape, and dispersion of the nanoparticles on a chemically diverse range of supports. Oxides are(More)
The nanoscroll-to-nanotube thermal transformation was studied for H 4 Nb 6 O 17 ‚4.4H 2 O scrolls, prepared by exfoliation of K 4 Nb 6 O 17. Thermal dehydration of the scrolls produces Nb 2 O 5 nanotubes at 400−450 °C. The nontopochemical transformation results in polycrystalline nanotubes; however, significant texturing with respect to the tube axis is(More)
Well-dispersed Rh(OH)3 nanoparticles were deposited in the interlayer galleries of a Dion-Jacobson type layered perovskite (ACa2Nb3O10: A=H or K). X-ray photoelectron spectra and zeta potential measurements suggest covalent bonding (Rh-O-Nb) between the nanoparticles and the niobate sheets. After calcination of Rh(OH)3/KCa2Nb3O10 at 350 degrees C in air,(More)
The intercalation of poly(allylamine) (PAA) into a synthetic fluoromica (Na-TSM) was studied in order to understand the subsquent process of gold nanoparticle intercalation into the interlayer galleries. The composition and structure of the PAA intercalation compound (PAA/Na-TSM) was strongly influenced by the pH of its synthesis. At pH 3.0, the fully(More)
The layered Dion-Jacobson phase perovskites HLaTa 2 O 7 ‚xH 2 O, HLaNb 2 O 7 ‚0.5H 2 O and structural variants of HLaNb 2 O 7 ‚0.5H 2 O were prepared and their AC and DC conductivities were measured as a function of temperature and atmosphere. The layered structure in HLaNb 2 O 7 ‚0.5H 2 O was modified by pillaring, exfoliation-restacking, and further(More)