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A comparative study of TiO 2 powders prepared by precipitation and sol-gel methods was conducted. Titanium tetrachloride and titanium tetraisopropoxide were used as the starting materials for the precipitation and sol-gel processes, respectively. The effects of the two different drying methods, freeze drying and normal drying at 100°C, of the precipitates on the properties of the prepared TiO 2 powders were also investigated. The effects of the synthesis methods on phase, surface area, crystallite size, and photodegradation of methylene blue were studied by XRD, SEM, TEM, BET, and UV/ Vis techniques. It was found that the major phase of the synthesized TiO 2 was anatase, but small amounts of the brookite phase (Ͻ10 %) were found in some samples. The synthesized anatase TiO 2 with no pretreatment was found to be stable up to 600°C for the samples prepared by the precipitation

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Bambusa multiplex (Lour.) Raeusch that is bamboo native to southern Asia and naturalized in other areas of Asia and America has a straight culm of a height of 5~8 m and a diameter of 0.03~0.05 m with small lumens between internodes of a length of 0.2~0.3 m. The culm is thick and heavy. It has been used as wood pulp and is expected to be the useful material for cellulose nanofibers. Its charcoal would be the promising carbon material for new fabricated devices. Therefore, we studied the structures of the green culm and the charcoal of Bambusa multiplex, mainly by X-ray diffraction (XRD) and fluorescent element analysis (XRF), analytical scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). Culms of Bambusa multiplex were sampled and seasoned in Thailand. Some of culms, cut off their branches and leaves, were carbonized around 700 o C for 3 h in a conventional charcoal kiln. SEM energy dispersive X-ray spectroscopy (EDS) mapping was performed using large depth of focus (LDF) mode with a JSM-7200F operated at 15 kV. For TEM/STEM, two aberration corrected microscopes, JEM-ARM 200F and JEM-3100F R05 were used and operated at 200 kV and 80 kV, respectively with a cold field emission gun. Both were configured with a Gatan US-1000 camera and a GIF Quantum ER energy filter for image recording and electron energy loss spectroscopy (EELS). Fig. 1 shows a light microscopy image of a transverse section of a green culm of Bambusa multiplex. Bambusa multiplex has a typical anatomical structure of bamboo [1] and resembles Phragmites australis (common reed) [2] and Arundo donax (giant reed) [3], which also belong to Poaceae Family, although it is different from those reeds in scale of outer shape and size of cells. Fig. 2(a) and Fig. 3 show the XRD and XRF results for different points a and b of a green culm and points A-E of a charcoal tube, as shown in Fig. 2(c). The culm and the charcoal tube are indicated in Fig. 2(b). XRD revealed that the green culm comprises amorphous cellulose and natural crystalline cellulose. XRF revealed that it contains Si atoms in and near its skin. With these results, we concluded that neither carbonization nor graphitization was completed for the charcoal at the present low carbonized temperature. The outside of the charcoal tube B still contained a large amount of Si like the green bamboo skin, which was confirmed by SEM EDS mapping in Fig. 4. Fig. 5(a) shows TEM image of a flake of the charcoal powder. The EELS fine structure of C-K edge obtained from the area enclosed by the circle is shown in Fig. 5(b). The excitation peaks π* and σ* related with the π and σ bonds appear in the amorphous charcoal. The charcoal powder is composed of carbon nanotubes or nanofibers disorderly distributed and graphite crystallites in very small areas, as seen in Fig. 6.

Nitrogen-doped titanium dioxide (N-doped TiO2) nanopowder was successfully prepared by the hydrothermal method. Titanium isopropoxide and urea were used as the starting precursors. The hydrothermal reaction was controlled at 200 °C for 2, 4 and 6 h. The white powder was obtained and dried for 24h. The crystal structure was identified by X-ray diffraction (XRD). A single phase of anatase structure was obtained without calcination steps. The morphology was investigated by field emission scanning electron microscopy (FESEM). The particles were irregular in shape and highly agglomerated. The chemical composition was determined by energy dispersive X-ray spectrometry (EDXS). The characteristic X-ray energy of titanium (Kα = 4.51 keV and Kβ = 4.93 keV), oxygen (Kα = 0.52 keV) and nitrogen (Kα = 0.39 keV) were observed. The functional group was identified by Fourier transform infrared spectrophotometry (FTIR). The wavenumbers in the range 668 to 1389 cm-1 corresponded to vibrations of Ti–O–Ti bond. The wavenumber in the range of 1442 to 1500 cm-1 could be attributed to the nitrogen species in the TiO2 network.