Microwave-assisted hydrothermal synthesis of monoclinic nitrogen-doped titania photocatalyst and its DeNO<Subscript>x</Subscript> ability under visible LED light irradiation

Nitrogen-doped titania (TiO_2−xN_y) nanoparticles with monoclinic phase were successfully prepared by a microwave-assisted hydrothermal process. The obtained TiO_2−xN_y powders showed high specific surface area, fine particle size, and excellent photocatalytic ability for the oxidative destruction of nitrogen monoxide under irradiation of monochromatic LED light with various wavelengths.     

Synthesis of TiO<Subscript>2</Subscript> nanotubes using different alkaline media and their applications in photocatalysis and DSSCs

TiO₂ nanotubes (TNTs) were successfully synthesized from different alkaline media (i.e., NaOH and KOH) by using a microwave hydrothermal process. The effects of different alkaline media on the formation of TiO₂ nanotubes and their physicochemical properties were investigated. The phases of different TiO₂ nanostructures were studied by using X-ray diffraction patterns. Morphologies of the nanostructures were observed with a transmission electron microscope. The optical properties of the nanostructures were evaluated through the absorption behavior using UV–Vis diffuse reflectance spectroscopy. The photocatalytic activities of the TiO₂ nanostructures were evaluated by the degradation of methylene blue aqueous dye solution under the simulated solar light irradiation. Similarly, the photovoltaic efficiencies of the prepared samples were investigated by making photo-anode layers in the Dye Sensitized Solar Cells (DSSCs). The results revealed that in comparison to the single layered TiO₂ nanostructures in the DSSC, creation of a double layer structure significantly enhanced the efficiency of DSSC.     

The β-decay of 91Sr

Both the continuous β-mray spectrum and the internal conversion electron spectrum of ⁹¹Sr have been studied with a π√2 magnetic spectrometer. The measurements yield an intensity of 30.8% for the first-forbidden unique β-decay to the ground state and a Q-value of 2.684 ± 0.004 MeV. The measured internal conversion coefficient of the 555.6 keV isomeric transition in ⁹¹Y is in excellent agreement with the theoretical value for an M4 transition. Seven less intense internally converted transitions were also studied. The results verify the J^π assignments of earlier studies and also provide new information for the transitions from which level structure configurations can be proposed.     

A system with non-aqueous birefringent microemulsions

Non-aqueous birefringent microemulsions were found in a system ofp-xylene, glycerol, triethanolammonium oleate and oleic acid. The microemulsions showed long term stability once formed, but failed to form spontaneously when the components were contacted. After partial separation by centrifugation, no signs of spontaneous reformation were found.     

Nb and N co-doped TiO2 for a high-performance deNO x photocatalyst under visible LED light irradiation

By a facile and rapid microwave-assisted hydrothermal reaction at 190 °C for 30 min, niobium and nitrogen co-doping TiO₂ nanoparticles were prepared. The obtained samples were characterized by XRD, UV–Vis spectroscopy, EDX analysis, and BET measurements. To evaluate the photocatalytic activity, destruction of NO _x gas under the irradiation of several LED lamps with various wavelengths were carried out. Although co-doping of Nb with N into TiO₂ resulted in the decrement of the specific surface area, it was useful to improve the photocatalytic activity for the oxidative destruction of NO, probably due to the effective reduction of the anion vacancy in the lattice which acts as the recombination center of the photo-induced electrons and holes.     

Water oxidation reaction promoted by MIL-101(Fe) photoanode under visible light irradiation

This work spotlights the recently discovered photoelectrocatalytic properties of iron-based metal–organic frameworks (MOFs) for water oxidation reaction (WOR) under visible light irradiation. The low efficiency of WOR is one of the biggest difficulties faced by photoelectrochemical solar energy conversion; the development of new photoanodes for WOR is greatly desired. In view of the fact that a higher efficiency for WOR was forecast thanks to the peculiar properties of MOFs, such as a highly ordered framework and homogenous porous structure, the photoelectrodes based on MIL-101(Fe) containing photo-active iron(III) clusters have been fabricated by using a drop-casting method and applied to photoelectrochemical water oxidation as photoanodes. XRD measurements revealed the successful formation of MIL-101(Fe) electrodes while retaining their framework structures. From the results of photoelectrochemical measurements, the optimal thickness of the MIL-101(Fe) electrodes was determined to be ca. 60 μm, and the optimized MIL-101(Fe) electrode was found to promote photoelectrochemical WOR under visible light irradiation more efficiently than conventional α-Fe₂O₃ electrodes. Moreover, electrochemical impedance spectroscopy measurements demonstrated a lower resistance of charge transfer at the interface between the MOF surface and the electrolyte, resulting in better photoelectrochemical performance of the MIL-101(Fe) electrode.