Akira Kira

In-situ spectrocyclic voltammetry investigations of the formation of a water oxidation catalyst [(bpy)2(H2O)RuORu(H2O)(bpy)2]4+ at a Nafion®-coated electrode

Abstract The monomeric ruthenium complex cis -[Ru(bpy) 2 (H 2 O) 2 ] 2+ was adsorbed into a Nafion® film coated onto an indium tin oxide (ITO) electrode. In-situ spectrocyclic voltammetric investigations under different pH conditions showed that the monomeric complex in the Nafion film dimerizes upon oxidation, with obvious spectral changes, to yield the corresponding oxo-bridged complex [(bpy) 2 (H 2 O)Ruue5f8Oue5f8Ru(H 2 O)(bpy) 2 ] 4+ which is a water oxidation catalyst. The reversible formation of the dimer and monomer during oxidation and reduction of the corresponding complexes at appropriate potentials was established by in-situ spectrocyclic voltammetry at a Nafion-film-coated ITO electrode.

Oxygen evolution by water oxidation with polynuclear ruthenium complexes

The electrochemical studies of a trinuclear ruthenium complex (Ruthenium red) have been carried out. Di- and tri-nuclear ruthenium complexes were adsorbed onto clay and ion-exchange resin and were then used as homogeneous and heterogeneous (clay-and resin-adsorbed) catalysts for water oxidation to evolve oxygen. The gas-chromatographic and mass-spectral data clearly show that oxygen evolved by water oxidation is catalysed by the polynuclear ruthenium complexes in the presence of CeIV oxidant. The turnover numbers and stabilities of the catalysts were evaluated under various conditions. The observed data show that the trinuclear ruthenium complexes are more efficient towards water oxidation than the dinuclear ruthenium complexes. Based on these results, the four-electron water oxidation process is discussed.

Complex formation between amphiphilic organic ligands and transition metal ions in monolayers and LB multilayers

The amphiphilic organic ligand (5-octadecyloxy-2-(2-pyridylazo)phenol, PARC18) formed various colored metal complexes with transition metal ions such as Fe(II), Co(II), Ni(II), Cu(II), Zn(II), VO(II), Ag(I), Cd(II), Hg(II) in monolayers, which were confirmed by the π–A isotherms and in situ absorption spectra of the monolayers. Well-defined LB films of the metal complexes can be fabricated by immersing the LB film of PARC18 ligand into aqueous solutions containing metal ions as verified from absorption spectra. Photoillumination can accelerate the metal complex formation process. The LB films fabricated by such methods are oriented with their functional groups inclined to the surface of the films as verified by the polarized absorption spectra measurement. Colored patterns can be written on the LB films by utilizing the photo-accelerated complex formations of the PARC18 LB film and metal ions. Different colors can be realized using a common PARC18 ligand by changing metal ions.

Monoculear ruthenium–ammine complexes as catalysts for water oxidation

Mononuclear ruthenium complexes catalyse water oxidation with evolution of oxygen under homogeneous as well as heterogeneous conditions.

Attempts in detection of neutrons on So-called cold nuclear fusion

Neutron emissions from electrolysis of D 2 O with palladium and palladium-titanium electrodes as well as from pressurized D 2 gas with titanium alloys have been measured. The neutron detector system was so designed to have very low background condition. Neutron-γ separation technique using liquid scintillator was applied to obtain essentially no γ ray background condition for neutron counting. Special care was taken to stabilize the detection system using event-by-event data recording. No significant signal of neutron emission was observed. Upper limits of emission probability of neutron have been determined to be 6×10 -3 s -1 , 1×10 -2 s -1 , and 2.3×10 -2 s -1 for Pd electrode, Pd-Ti electrode, and pressurized gas systems. These values are orders of magnitude lower than that presented by Jones paper (0.4 s -1 ).

Characteristics of phosphor used for beam monitoring: Intensity growth of scintillation and long-lived residual emission observed on steady state γ-radiolysis

Abstract The visible scintillation around 690 nm from Desmarquest AF995R, which is used for real-time beam monitoring, was investigated on steady state γ-radiolysis at room and low temperatures. The temperature dependence of the scintillation intensity indicates the existence of more than two processes with different activation energies. The newly found growth of the scintillation which continues for over several hours on continuous irradiation shows saturating behavior. Weak residual emissions remaining for over a day after stopping the irradiation were also observed.

Aqueous scintillator based on chemiluminescence of luminol

Abstract A chemiluminescence scintillator was proposed as a possible scintillator in an aqueous solution where the usual scintillators do not function. The new scintillator is based on chemiluminescence in which an active chemical species induced by irradiation of water is involved. An alkaline luminol solution containing H2O2 was examined from this viewpoint.

Electrochemical reduction of carbon dioxide on titanium diboride

The electrochemical reduction of carbon dioxide has been studied on metal or surface-modified metal cathodes and semiconductor photocathodes [l-7]. The reaction pathway and the efficiency strongly depend on the electrode material [2,4]. The reduction of carbon dioxide results from the addition of hydrogen followed by the subtraction of the oxygen atom. The electrode surface must be hydrogen-rich to function as a hydrogen source, and parly oxidizable to function as an oxygen sink and to allow the adsorption of carbon dioxide molecules. Titanium, platinum and nickel electrodes show a strong affinity for hydrogen atoms [Sl. However, previous studies on the electrochemical reduction of carbon dioxide on these electrodes in aqueous media have revealed that the major product is hydrogen and the efficiency of the carbon dioxide reduction is low [2,4]. This low efficiency results from either poor adsorption of carbon dioxide or an adsorption state unfavorable for succeeding steps. Inclusion of a second element in the electrode material may improve surface properties. Boron is a promising candidate for the second element; it can form B-O and B-C bonds [9] that serve to accumulate carbon dioxide on the surface, and metal borides provide a variety in stoichiometry [9] that increases the chance for the partial oxidation by carbon dioxide for the oxygen subtraction. This preliminary note is concerned with the properties of a titanium diboride (TiB,) cathode in the electrochemical reduction of carbon dioxide. Titanium diboride is an electroconductive ceramic and an atomically homogeneous mixture of titanium and boron.