Catalytic etching of {100}-oriented diamond coating with Fe, Co, Ni, and Pt nanoparticles under hydrogen

Etching of a highly {100}-oriented diamond coating, {100}HODC, with hydrogen gas using Fe, Co, Ni, and Pt nanoparticles as a catalyst was examined at high temperatures over 700 degrees C by high-resolution scanning electron microscopy and Raman spectroscopy. The metal atoms vacuum-evaporated onto the {100}HODC formed nanopartides themselves when heated at high temperatures; e.g. 700 degrees C, in a flowing gas mixture of H(2) (10%) + N(2) (90%). At 800 degrees C. short nano-channels and etch pits holding metal nanoparticles were formed by Fe. Co. and Ni. The shapes of the Co and Ni nanoparticles in the etch pits were affected by the shape of the etch pits; reversed pyramidal shape. On the other hand, the top view of the Fe nanoparticles embedded in the etch pits showed a distorted round shape, probably due to the formation of something such as iron carbide, while the carbon content was unknown. Apparently, etching of the {100}HODC by Pt nanoparticles was observed after the treatment at 1000 degrees C. The difference in the catalytic etching behavior among these metal particles, the potential etching mechanism of diamonds with hydrogen by metal nanoparticles, probably as melted metal nanoparticles, and the formation mechanism of vacant etch pits were discussed.ArticleDIAMOND AND RELATED MATERIALSjournal articl

Catalytic etching of synthetic diamond crystallites by iron

For the expansion of the functionality of diamond crystallites by modification of surface morphology, catalytic etching of synthetic diamond crystallites at 1173 K by iron, which were loaded by the impregnation method using an aqueous solution of iron nitrate; in a streaming mixed gas (pH(2) = 0.1 MPa, pN(2) = 0.9 MPa), has been investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The dependence of the crystal planes {111} and {100}, of the diamond crystallites and the loading amount of iron on the diamond on the etching behavior by iron particles, the morphology of the etch pits, and potential formation of iron carbide through the catalytic etching, were discussed.ArticleAPPLIED SURFACE SCIENCEjournal articl

Structural analyses of RuO(2)-TiO(2)/Ti and IrO(2)-RuO(2)-TiO(2)/Ti anodes used in industrial chlor-alkali membrane processes

The morphology and composition of RuO(2)-TiO(2)/Ti and IrO(2)-RuO(2)-TiO(2)/Ti anodes, which have been used for the production of chlorine for more than 10 years, were analyzed by various methods; such as high-resolution scanning electron microscopy, high-resolution Auger electron spectroscopy, electron probe X-ray emission microanalysis and X-ray diffraction analysis. Drastic changes in the surface morphology, including partial exfoliation of a small amount of the oxide layer and a reduction in the content of ruthenium species through dissolution, were observed for the RuO(2)-TiO(2)/Ti anode. For the IrO(2)-RuO(2)-TiO(2)/Ti anode, on the other hand, there were moderate changes in the surface morphology and moderate dissolution of iridium and ruthenium species.ArticleJOURNAL OF APPLIED ELECTROCHEMISTRYjournal articl

Steam activation of boron doped diamond electrodes

Boron doped diamond (BDD) electrodes were activated in steam at various temperatures, resulting in high quality BDD electrodes with a porous microstructure. Distinct columnar structures were observed by scanning electron microscopy. The electrochemically active surface area of the steam-activated BDD was up to 20 times larger than the pristine BDD electrode owing to the porous texture. In addition, a widening of the potential window was observed after steam activation, suggesting that the quality of BDD was enhanced due to oxidative removal of graphitic impurities during the activation process.ArticleELECTROCHIMICA ACTA. 56(16):5599-5604 (2011)journal articl

Oxygen reduction characteristics of several valve metal oxide electrodes in HClO(4) solution

In the search for active cathode catalysts for polymer electrolyte fuel cells (PEFCs) using inexpensive materials several valve metal oxide electrodes TiO(x) ZrO(x), and TaO(x) with corresponding binary oxide electrodes were selected for the evaluation of catalytic activity for oxygen reduction reaction (ORR) by means of cyclic voltammetry in 0 1 M HClO(4) at 60 C These oxide electrodes were prepared mainly by the dip-coating method on a titanium plate substrate at a temperature between 400 degrees C and 500 degrees C and were characterized by scanning electron microscopy (SEM) X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS) Among the oxide-coated electrodes investigated Ti(0) (7)Zr(0) (3)O(x)/Ti provided the highest ORR specific activity with an onset potential E(ORR) of 0 86V vs RHE during the cathodic potential sweep Fine TaO(x) particles prepared as an extension of the dip-coating method showed very high catalytic activity determined by means of hydrodynamic voltammetry in 0 1 M HClO(4) at 30 degrees C with an E(ORR) of 0 90 V vs RHEArticleELECTROCHIMICA ACTAjournal articl

Enhanced activity and stability of Pt/C fuel cell anodes by the modification with ruthenium-oxide nanosheets

Ruthenium-oxide nanosheet (RuO(2)ns) crystallites with thickness less than 1 nm were prepared via chemical exfoliation of a layered potassium ruthenate and deposited onto carbon supported platinum (Pt/C) as a potential co-catalyst for fuel cell anode catalysts. The electrocatalytic activity towards carbon monoxide and methanol oxidation was studied at various temperatures for different RuO(2)ns loadings. An increase in electrocatalytic activity was evidenced at temperatures above 40 degrees C, while little enhancement in activity was observed at room temperature. The RuO(2)ns modified Pt/C catalyst with composition of RuO2:Pt=0.5:1 (molar ratio) exhibited the highest methanol oxidation activity. CO-stripping-voltammetry revealed that RuO(2)ns promotes oxidation of adsorbed CO on Pt. In addition to the enhanced initial activity, the RuO(2)ns modified Pt/C catalyst exhibited improved stability compared to pristine Pt/C against consecutive potential cycling tests.ArticleELECTROCHIMICA ACTA. 55(3):857-864 (2010)journal articl

Activity and Durability of Ternary PtRuIr/C for Methanol Electro-oxidation

Carbon supported Pt(1)Ru(1)Ir(x) (0 <= x <= 2) nanoparticles were prepared by it compare nation reductive pyrolysis method and their electrocatalytic activity toward methanol electro-oxidation at 25, 40, and 60 degrees C was investigated. The mass activity (current normalized by the mass of Pt) for methanol electro-oxidation increased as it function of Ir coefficient and cell temperature. Despite the increase in methanol electro-oxidation activity, the addition of Ir does not affect the CO tolerance of the ternary electrocatalyst. The addition of Ir also enhances the durability of the catalyst. The enhancement in activity and durability is discussion based on CO stripping measurements and X-ray photoelectron spectroscopy analysis of the catalysts. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3060111] All rights reserved.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY. 156(3):B397-B402 (2009)journal articl

A gas-diffusion cathode coated with oxide-catalyst for polymer electrolyte fuel cells using neither platinum catalyst nor carbon catalyst-support

To overcome the fundamental disadvantages of conventional cathodes for polymer electrolyte fuel cells (PEFCs), such as dissolution and migration of platinum-based catalysts and consumption of the carbon catalyst-support, a substantially novel gas-diffusion cathode has been proposed. The electrode was made of a porous oxide catalyst, which was coated on the inner and outer surfaces of a macro-porous titanium sheet substrate, using neither a platinum catalyst nor carbon catalyst-support. The suitability of this cathode for PEFCs, tested using a highly porous iridium oxide strongly coated on the macro-porous titanium sheet substrate, was confirmed by successful power generation. The gas-diffusion electrode functioned not only as the cathode but also as an anode of a PEFC.ArticleELECTROCHIMICA ACTA. 105:224-229 (2013)journal articl

Rice transposable elements are characterized by various methylation environments in the genome

<p>Abstract</p> <p>Background</p> <p>Recent studies using high-throughput methods have revealed that transposable elements (TEs) are a comprehensive target for DNA methylation. However, the relationship between TEs and their genomic environment regarding methylation still remains unclear. The rice genome contains representatives of all known TE families with different characteristics of chromosomal distribution, structure, transposition, size, and copy number. Here we studied the DNA methylation state around 12 TEs in nine genomic DNAs from cultivated rice strains and their closely related wild strains.</p> <p>Results</p> <p>We employed a transposon display (TD) method to analyze the methylation environments in the genomes. The 12 TE families, consisting of four class I elements, seven class II elements, and one element of a different class, were differentially distributed in the rice chromosomes: some elements were concentrated in the centromeric or pericentromeric regions, but others were located in euchromatic regions. The TD analyses revealed that the TE families were embedded in flanking sequences with different methylation degrees. Each TE had flanking sequences with similar degrees of methylation among the nine rice strains. The class I elements tended to be present in highly methylated regions, while those of the class II elements showed widely varying degrees of methylation. In some TE families, the degrees of methylation were markedly lower than the average methylation state of the genome. In two families, dramatic changes of the methylation state occurred depending on the distance from the TE.</p> <p>Conclusion</p> <p>Our results demonstrate that the TE families in the rice genomes can be characterized by the methylation states of their surroundings. The copy number and degree of conservation of the TE family are not likely to be correlated with the degree of methylation. We discuss possible relationships between the methylation state of TEs and their surroundings. This is the first report demonstrating that TEs in the genome are associated with a particular methylation environment that is a feature of a given TE.</p

Synthesis of ordered mesoporous ruthenium by lyotropic liquid crystals and its electrochemical conversion to mesoporous ruthenium oxide with high surface area

In ordered to prepare high capacitance pseudo-capacitive oxides, it is important to design nanostructures with appreciable mesopores. Supramolecular templating has become a popular method to synthesize ordered mesoporous metals; however, the application of the same technique to synthesis of high surface area oxides is more demanding. We present here, the synthesis of ordered mesoporous ruthenium metal by lyotropic liquid crystal templating and its electrochemical conversion to ordered mesoporous ruthenium oxide by a simple, room temperature procedure. The bulk, unsupported metallic ordered mesoporous ruthenium exhibits high surface area of 110 m(2) g(-1), which is comparable to typical supported Ru nanoparticles. The oxide analogue gives a high specific capacitance of 376 Fg(-1), owing to the porous structure. These results demonstrate a possible facile and generic process to synthesize oxides with ordered nanostructures by utilization of the various phases that can be obtained with lyotropic liquid crystalline templates such as cubic, hexagonal, lamellar, etc.ArticleJOURNAL OF POWER SOURCES. 204:244-248 (2012)journal articl