Sakamoto, Tomokazu
Masuda, Teruyuki
Yoshimoto, Koji
Kishi, Hirofumi
Yamaguchi, Susumu
Matsumura, Daiju
Tamura, Kazuhisa
Hori, Akihiro
Horiuchi, Yousuke
Serov, Alexey
Artyushkova, Kateryna
Atanassov, Plamen
Tanaka, Hirohisa
NiO/Nb2O5/C (8:1), (4:1), (2:1), NiO/C, and Ni/C catalysts for hydrazine electrooxidation were synthesized by an evaporation drying method followed by thermal annealing. Prepared catalysts were characterized by X-ray diffraction (XRD), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectrometry (EDS), and X-ray absorption fine structure (XAFS). Catalytic activity, durability, and selectivity in the reaction of hydrazine electrooxidation were evaluated in alkalinemedia. The highest catalytic activity in mentioned above reactionwas found forNi/C, followed by:NiO/Nb2O5/C (8:1), NiO/Nb2O5/C (4:1). NiO/Nb2O5/C (2:1) whiles NiO/C has almost no activity for hydrazine oxidation. NiO/Nb2O5/C (8:1) and (4:1) had a highest stability during electrooxidation of hydrazine at 60 degrees C. It was explained by oxygen defect of NiO in NiO/Nb2O5/C from XAFS analysis. The selectivity hydrazine electrooxidation as measured by ammonia production resulted in observation that metallic Ni surface facilitates N-N bond breaking of hydrazine, which was confirmed by density functional theory (DFT) calculations. (C) The Author(s) 2017. Published by ECS. All rights reserved.
The electrochemical behaviour of TiO2 under X-ray irradiation was studied. Under X-ray irradiation a current, a negative shift in the rest potential, and electrochemical oxidation and decomposition of [Fe-II(CN)(6)](4-) were clearly observed. The incident photon-current conversion efficiency and energy conversion efficiency was 400-2000% and 0.2-2%, respectively, depending on sample conditions. These results show that the photoelectrochemical reactions were promoted by X-rays with a high incident photon-current conversion efficiency. The photocurrent and photopotential were observed above 4.965 keV, which corresponds to the Ti-K edge, indicating that electron-hole pairs are formed during the relaxation process of the excited Ti atoms. (c) 2007 Elsevier Ltd. All rights reserved.
In a rotating apparatus, a ring gear with which a rotating pinion provided on an upper rotation body meshes is provided on the inner periphery of an inner ring on the lower traveling body side. A grease bath is formed in the inner side of the inner ring. A center joint is installed in an opening formed at the position of rotation center of the upper rotation body. The center joint is connected to a connection wall extended from a bath forming wall of the grease bath. A sealing member for sealing the grease bath is provided at a position between the upper face of the connection wall and the lower face of a frame of the upper rotation body, and the position is more toward the outer periphery side than the installation portion of the center joint. The sealing member is a circular elastic member and has a height dimension larger than the space between the connection wall and the frame. The sealing member is removably fixed to one contact portion on either the frame or the connection wall with which portion the sealing member is in contact. The other contact portion is made to be a circular sliding portion, which is projected toward the radially inside.
A gas producer capable of filling a sufficient amount of a gas-producing agent in a combustion chamber with a housing maintained in high safety and capable of uniformly and efficiently combusting the gas-producing agent in the combustion chamber. A gas producer (A) has a housing with an initiator shell (1) and a closure shell (2), a combustion chamber (5) in which a gas-producing agent (4) is placed, and igniting means (7) for igniting and combusting the gas-producing agent (4). The initiator shell (1) and the closure shell (2) have semispherical end plate sections (10, 14). The ratio (H/D) between the outer diameter (D) of hollow-cylindrical sections (9, 13) continuously formed from the end plate sections (10, 14) and the length (H) of a housing is set to a range of 0.4 - 1.3. The igniting means (7) has an inner hollow-cylindrical body (16) with fire transmission holes (15) and a fire transmitter agent (17) placed in the inner hollow-cylindrical body (16). The ratio (d/D) between the outer diameter (d) of the inner hollow-cylindrical body (16) and the outer diameter (D) of the end plate sections (10, 14) is set to a range of 0.1 - 0.5.
Platinum group metal-free (PGM-free) catalysts based on transition metal-nitrogen-carbon nanomaterials have been studied by a combination of ex situ and in situ synchrotron X-ray spectroscopy techniques; high-resolution Transmission Electron Microscope (TEM); Mossbauer spectroscopy combined with electrochemical methods and Density Functional Theory (DFT) modeling/theoretical approaches. The main objective of this study was to correlate the HO2- generation with the chemical nature and surface availability of active sites in iron-nitrogen-carbon (Fe-N-C) catalysts derived by sacrificial support method (SSM). These nanomaterials present a carbonaceous matrix with nitrogen-doped sites and atomically dispersed and; in some cases; iron and nanoparticles embedded in the carbonaceous matrix. Fe-N-C oxygen reduction reaction electrocatalysts were synthesized by varying several synthetic parameters to obtain nanomaterials with different composition and morphology. Combining spectroscopy, microscopy and electrochemical reactivity allowed the building of structure-to-properties correlations which demonstrate the contributions of these moieties to the catalyst activity, and mechanistically assign the active sites to individual reaction steps. Associated with Fe-N-x motive and the presence of Fe metallic particles in the electrocatalysts showed the clear differences in the variation of composition; processing and treatment conditions of SSM. From the results of material characterization; catalytic activity and theoretical studies; Fe metallic particles (coated with carbon) are main contributors into the HO2- generation.
Taminato, Sou
Hirayama, Masaaki
Suzuki, Kota
Tamura, Kazuhisa
Minato, Taketoshi
Arai, Hajime
Uchimoto, Yoshiharu
Ogumi, Zempachi
Kanno, Ryoji
An epitaxial-film model electrode of LiCoO2(104) was fabricated on SrRuO3(100)/Nb:SrTiO3(100) using pulsed laser deposition. The 50 nm thick LiCoO2(104) film exhibited lithium (de-)intercalation activity with a first discharge capacity of 119 mAh g(-1) between 3.0 and 4.4 V, followed by a gradual capacity fading with subsequent charge-discharge cycles. In contrast, a 3.2 nm thick Li3PO4-coated film exhibited a higher intercalation capacity of 148 mAh g(-1) with superior cycle retention than the uncoated film. In situ surface X-ray diffraction measurements revealed a small lattice change at the coated surface during the (de-)intercalation processes compared to the uncoated surface. The surface modification of LiCoO2 by the Li3PO4 coating could lead to improvement of the structural stability at the surface region during lithium (de-)intercalation at high voltage. (C) 2016 Elsevier B.V. All rights reserved.
Confinement of hydrogen molecules at graphene-substrate interface has presented significant importance from the viewpoints of development of fundamental understanding of two-dimensional material interface and energy storage system. In this study, we investigate H-2 confinement at a graphene-Au interface by combining selective proton permeability of graphene and the electrochemical hydrogen evolution reaction (electrochemical HER) method. After HER on a graphene/Au electrode in protonic acidic solution, scanning tunneling microscopy finds that H-2 nanobubble structures can be produced between graphene and the Au surface. Defect dependence of the bubble formation suggests that intrinsic defects in graphene, which have high hydrogen permeation barrier but are permeable for protons, are involved in the fundamental mechanism of bubble formation. Strain analysis by Raman spectroscopy also shows that atomic size roughness on the graphene/Au surface originating from the HER-induced strain relaxation of graphene plays significant role in formation of the nucleation site and H-2 storage capacity. The result presented herein would provide further understanding of molecular confinement at graphene-based interface and development of novel energy material.
The structure of the perfluorosulfonated ionomer (PFSI)/Pt(111) interface in a membrane electrode assembly (MEA)-like configuration of a polymer electrolyte membrane (PEM) fuel cell, that is, a vacuum evaporated Pt layer/PEM(Nafion membrane)/PFSI(adhesion Nafion layer)/Pt(111) single crystal, and its bias-induced change were investigated by surface X-ray scattering measurement at an atomic level. Crystal truncation rod measurement shows that PFSI adsorbed on the Pt(111)-(1 x 1) surface without bias. When the Pt(111) electrode was positively biased to form Pt oxide, the PFSI layer was detached from the Pt surface and oxygen atoms penetrated into the Pt lattice.
Gaining a thorough understanding of the reactions on the electrode surfaces of lithium batteries is critical for designing new electrode materials suitable for high-power, long-life operation. A technique for directly observing surface structural changes has been developed that employs an epitaxial LiMn(2)O(4) thin-film model electrode and surface X-ray diffraction (SXRD). Epitaxial LiMn(2)O(4) thin films with restricted lattice planes (111) and (110) are grown on SrTiO(3) substrates by pulsed laser deposition. In situ SXRD studies have revealed dynamic structural changes that reduce the atomic symmetry at the electrode surface during the initial electrochemical reaction. The surface structural changes commence with the formation of an electric double layer, which is followed by surface reconstruction when a voltage is applied in the first charge process. Transmission electron microscopy images after 10 cycles confirm the formation of a solid electrolyte interface (SEI) layer on both the (111) and (110) surfaces and Mn dissolution from the (110) surface. The (111) surface is more stable than the (110) surface. The electrode stability of LiMn(2)O(4) depends on the reaction rate of SEI formation and the stability of the reconstructed surface structure.
The behavior of halide ions on the Au(111) electrode surface in two ionic liquids (ILs), 1-buthyl-1-methylpyrrolidiniun bis(trifluoromethylsulfonyl)amide ([BMP]TFSA) and 1-buthyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([BMIM]TFSA), was investigated by monitoring the structure of the electrode surface. The potential dependences of the X-ray diffraction intensity, which originate from the Au(111)-(1 X 1) structure and the surface normal structure, were measured simultaneously with cyclic voltammograms. We considered the effects of both ion concentration and ion species. The results revealed that halide ions are coadsorbed with IL molecules on the electrode surface and increase the mobility of surface atoms. By contrast, the Au(111) surface does not reconstruct to the (p X root 3) structure, even in the IL containing 200 mM Br-. This suggests that the interaction between halide ions and surface Au atoms is weaker than that between IL molecules and surface Au atoms; that is, the surface properties are mainly governed by adsorbed IL molecules. Furthermore, a comparison of the two ILs revealed that the effect of halide ions on the structure of the Au(111) electrode surface depends on the strength of the interaction between IL molecules and surface Au atoms.
Structure changes of LiNi0.5Mn0.5O2 were detected at the electrode/electrolyte interface of lithium cell using synchrotron X-ray scattering and two-dimensional model electrodes. The electrodes were constructed by an epitaxial film of LiNi0.5Mn0.5O2 synthesized by pulsed laser deposition (PLD) method. The orientation of the film depends on the substrate plane; the 2D layer of LiNi0.5Mn0.5O2 is parallel to the SrTiO3(1 1 0) substrate ((1 1 0) LiNi0.5Mn0.5O2H(1 1 0) SrTiO3), while the 2D layer is perpendicular to the SrTiO3(1 1 1) substrate ((0 0 3) LiNi0.5Mn0.5O2//(1 1 1) SrTiO3). The in situ X-ray diffraction of LiNi0.5Mn0.5O2(0 0 3) confirmed three-dimensional lithium diffusion through the two-dimensional transition meal layers. The intercalation reaction of LiNi0.5Mn0.5O2 will be discussed. (C) 2007 Elsevier B.V. All rights reserved.
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