Papers by Keyword: Nanoporous

Abstract: Thin-film titania templates were fabricated under different processing conditions. The dependencies of pore morphology and pore formation rate on process parameters were evaluated. It was found that under optimized electrolyte condition and anodizing voltage, a self-organized nanostructure consisting of porous TiO2 was obtained. 1 M Na2SO4 solution with the addition of 0.35 wt.% NaF and voltage potential of 30V were used. SEM images of templates showed very thin layer of ~70 nm thickness with worm-like pores. Pore diameter and average pore spacing of center to center on the surface were ~10 nm and 20 nm, respectively. The nanoporous TiO2 thin film will be very useful gas sensing and photocatalytic materials due to their large surface areas and high reactivities.

Abstract: Nanoporous SiC membrane was developed on the porous alumina plate for the hydrogen separation using preceramic polymers such as polyphenylcarbosilane. The prepared preceramic polymers were characterized with FT-IR, TGA, GPC and XRD. Nanoporous SiC membrane was derived from the preceramic polymer using a spin coating method. The SiC membrane spin coated using 20 wt.% of polyphenylcarbosilane solution in cyclohexane does not show any cracks on the surface after heat treatment at 800oC. The average thickness of the SiC membrane is about 1µm. SiC coated porous alumina possesses asymmetric pore size distribution. There are micropores that originated from porous alumina substrate, and nanopores that derived from amorphous state of SiC membranes. The pore size distribution measurement showed that the sample contains 1-3 nm sized nano pores.

Abstract: The precursor solutions containing TiO2 sol for nanoporous films were prepared by hydrolyzing titanium(IV) isopropoxide and adding trehalose dihydrate. The porous and thick TiO2 film was prepared by dip-coating technique on glass substrate and heating at 500 °C. The film was composed of nano sized particles (10-20 nm) and pores (7 nm). The specific surface area of the film was 163 m2/g. The film had humidity-sensitive electrical resistance at room temperature.

Abstract: The characteristic of nanoporous SiO2 thin film prepared by sol-gel method with catalyst HF was studied by scanning electron microscopy, Fourier transform infrared, HP analyzer series and ellipsometry. Results showed the incorporation of HF effectively adjusted the pore size and distribution, and lowered the leakage current density and dielectric constant. This might be related to the weak acidity of HF, which properly controlled the velocity of chemical reaction in solution, and to the introduction of strong Si-F bonds, which had the lower electronegative and the larger volume.