Disk-shaped tungsten(VI) oxide (D-WO3) particles were synthesized according to a previously reported method consisting of pyrolysis, precipitation, and calcination, and the calcination temperature was changed (200–600 °C). The samples were characterized by field-emission
scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, the Brunauer– Emmett–Teller single-point method, and diffuse reflectance spectroscopy. In addition, to evaluate the photocatalytic activities of the samples, the mineralization of acetic acid
to carbon dioxide (CO2) was measured by loading Pt particles onto the surface of the samples by photodeposition and irradiating them in an aqueous suspension with a blue light-emitting diode. Increasing the calcination temperature was associated with several changes: the crystallites
grew larger, increasing the crystallinity; the specific surface area decreased, decreasing the adsorption capacity; and the rate of the photocatalytic CO2 evolution reaction increased. Pt-loaded (0.1 wt%) D-WO3 calcined at 600 °C showed the highest activity with a
CO2 evolution rate of 5.9 μmol h−1. These results indicated that improving the crystallinity of the D-WO3 samples was effective in increasing their photocatalytic activities.
Nickel-nanoparticle-containing polyimide composite films were prepared by liquid-phase reduction of Ni2+ ions with potassium borohydride (KBH4). This preparation method could be repeated to increase the number of the nanoparticles in the films.
The electrorheological (ER) properties of composite materials consisting of a nematic liquid crystal (LC) and gold nanoparticles (GNPs) coated with bistolane-based mesogenic groups were studied. The GNPs were coated by normal alkyl chains and the fluorescent LC compounds, of which the molecular structure was similar to that of the LC matrix. The dispersity of the GNPs in the nematic LC was investigated by polarizing optical microscopy (POM). In order to improve the ER effect of the composite, a simple strategy was investigated from the viewpoint of a material design in surface-modified GNPs by lateral substitution of the mesogenic groups. The presence of the GNPs in the nematic LC led to a slightly enhanced ER effect compared to that observed for only the nematic LC. This study demonstrates the potential of a hybrid system consisting of LCs and GNPs to yield a larger ER effect.
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