Naohiro Shimoda

Physical mixing of TiO2 with sponge nickel creates new active sites for selective CO methanation

Ni–α-Al2O3, Ni–SiO2, Ni–γ-Al2O3, Ni–TiO2, and Ni–ZrO2 were prepared by physical mixing of metal oxides with sponge Ni, and the effect of physical contact of the metal oxides with sponge Ni on selective CO methanation was examined. The prepared Ni–TiO2 catalyst removed CO more deeply and suppressed CO2 methanation better relative to the other catalysts. The metal oxide nature of the prepared Ni catalysts affected the CO2 methanation activity, as well as the reverse water gas shift activity. Moreover, the catalytic performance for the five catalysts was not related to contact time. These results predicted the appearance of new active sites between sponge Ni and the metal oxides.

Blue and orange oxygen responsive emissions in the solid state based on copper(I) complexes bearing dodecafluorinated diphosphine and 1,10-phenanthroline derivative ligands

Reversible oxygen sensing abilities based on blue and orange photoluminescence in the solid state are achieved by using newly synthesized copper(I) complexes bearing diimine and dodecafluorinated diphosphine ligands. We found that the blue emission of [Cu(dmp)(dfppe)]PF6 (dmp = 2,9-dimethyl-1,10-phenanthroline, dfppe = 1,2-bis[bis(pentafluorophenyl)phosphino]ethane) in the solid state is very strong under argon, while it is nearly invisible under air. Single crystal X-ray structural analysis reveals that the complex has significant columnar void spaces. [Cu(dmp)(dfppe)]PF6 shows an extremely long lifetime of the emission in the solid state under an argon atmosphere (τ1 = 160 μs (88%), τ2 = 22 μs (12%)), which is one of the largest values for all copper(I) complexes bearing diimine ligands, and it is drastically decreased under air (τ1 = 2.4 μs (85%), τ2 = 0.5 μs (15%)). The employment of the dfppe ligand markedly increases the contribution of ligand centred transition, leading to the long-lived excited state. The orange oxygen responsive emission of [Cu(47dmp)(dfppe)]PF6 (47dmp = 4,7-dimethyl-1,10-phenanthroline) is also examined with the help of an investigation of the photophysics of five new compounds of the copper(I) complexes.

Synthesis of tetragonal zirconia in mesoporous silica and its catalytic properties for methanol oxidative decomposition

The synthesis of zirconia with large specific surface area by the hard template method has been conducted using KIT-6 mesoporous silica. Composite materials of tetragonal zirconia and silica were successfully synthesized by the decomposition of zirconia sources in the mesoporous space of KIT-6, while zirconia in the monoclinic and tetragonal phases was synthesized by the conventional pyrolysis method from the same zirconium sources. The formation behavior of tetragonal zirconia depends on the zirconium source, the pore size of mesoporous silica, the amount of the introduced zirconia source, and the calcination temperature. We conclude that the crystallization of zirconia in the mesoporous space results in the formation of fine zirconia particles (crystallite size effect), leading to the formation of a pure tetragonal zirconia crystal. Furthermore, the nanosized tetragonal zirconia possessing large BET specific surface area was synthesized by removing the silica component in the zirconia–silica composite with alkaline treatment. Additionally, we have evaluated the catalytic performance of tetragonal zirconia materials for methanol oxidative decomposition. Among the zirconia samples synthesized in the present study, the sample prepared by the hard template method and calcined at 800 °C exhibited the highest activity for methanol oxidation. We deduce that crystallinity of zirconia and high BET specific surface area are necessary to achieve high catalytic activity.