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Multiwalled carbon nanotubes (MWCNTs) have been successfully synthesized by using a relatively simple method, known as modified Wolff-Kishner reduction process. Transmission electron microscopy (TEM) has shown the as-prepared MWCNTs possess straight morphologies with average inner and outer diameters, between 2 to 7 nm and 5 to 15 nm, respectively. Ultraviolet-visible (UV-Vis) absorption measurement has been conducted for the first time. The correlation between energy of the π plasmon absorbance (Eπ) and nanotube diameter (dCNT) for the as-prepared MWCNTs shows contradiction to the empirical relationship as Eπ = 4.8 + 0.7 / (dCNT)2. Other optical characteristics like transmittance, reflectance and refraction index also have been studied. This work explores the optical property of the as-prepared MWCNTs and thus provides better understanding about the feasibility of this synthesis technique.

Titania nanotubes (TNTs) have been successfully synthesized by hydrothermal treatment of anatase TiO2 powder in NaOH solution at 110°C for 90 hours and then annealed at the temperature of 400°C. The morphology and crystalline structure of the nanotubes were characterized by using transmission electron microscopy (TEM) and X-ray diffraction (XRD). The average specific surface area of the particle was probed using gas adsorption-desorption measurements, and average particle size was calculated from the specific surface area. Based on the microscopic observations on the transformation process, it indicated that the formation of nanotubular products remained in their shape after the annealing process. While XRD results confirmed the nanotubes were composed of pure anatase TiO2 nanoparticles.