Biomedical subjects
Publications and source records attributed to Masato Machida.
Selective electrocatalytic hydrogenation of NO3- to N2 in water has successfully been achieved at room temperature using a membrane-electrode assembly (MEA) consisting of an H+ -conducting solid polymer electrolyte (Nafion-117) and a surface-modified Pt cathode.
The Dion-Jacobson series of triple-layered perovskite tantalates (MCa2Ta3O10, M = Cs, Na, H, and C6H13NH3) were synthesized to evaluate their photocatalytic activity for overall water splitting to evolve H2/O2 under UV irradiation. The photocatalytic activity was susceptible to the hydration of interlayer space. The hydrous Na phase exhibited much higher activity (H2: 308 micromol.h(-1)) compared to the anhydrous Cs phase (24 micromol.h(-1)) and the hydrous H phase (22 micromol.h(-1)) in the presence of 0.5 wt % Ni impregnated. H2O/D2O isotopic experiment suggested that the hydrated interlayer plays as an active site for water splitting, where the high mobility of water molecule in the interlayer should correlate with the total photocatalytic activity. The FLAPW electronic structure calculation demonstrated that the terminating oxygen site, O4, which faces to the interlayer space, contributes largely to the top of the valence band. Judging from comparison with the double-layered tantalates, MLaTa2O7, in our previous study, the contribution of terminating oxygen site to the band structure is supposed to depend on the number of perovskite layers.
A sulfur redox cycle between La(2)O(2)SO(4)(S(6+)) and La(2)O(2)S(S(2-)) phases was found for the first time to achieve the oxygen storage of 2 mol O(2) mol(-1), which is eight times larger than that of the conventional CeO(2)-ZrO(2) system.
Platinum intercalated into a hydrotalcite-like solid, Mg0.74Al0.26(OH)2(NO3)0.26, was found to catalytically reduce interlayer nitrate (NO3-) to N2/N2O so as to give rise to a large surface area micro/mesoporous structure at lower temperature of ca. 300 degrees C, compared to 500 degrees C required for the decomposition of the pristine hydrotalcite phase.
The layered and hexagonal yttrium-based surfactant mesophases templated by anionic surfactant (C(n)()H(2)(n)()(+1)OSO(3)(-) and C(n)()H(2)(n)()(+1)SO(3)(-)) assemblies were synthesized by the homogeneous precipitation method using urea. The layered mesophase is formed of a layered but curving or bending microstructure and transformed into a hexagonal mesostructure with complex and attractive morphologies such as plate-, dish-, and crown-like shapes. The specific surface area of the mesostructured solid increases from 53 m(2) g(-)(1) for the layered form to 251-322 m(2) g(-)(1) for the hexagonal form, due to the formation of hexagonally arranged cylindrical micropores loosely occupied by surfactant molecules. The anion-exchange of the hexagonal mesophase with acetate species results in a mesoporous material with a specific surface area of as large as 545 m(2) g(-)(1).