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We report the synthesis of N-doped TiO(2) nanofibers and high photocatalytic efficiency in generating hydrogen from ethanol-water mixtures under UV-A and UV-B irradiation. Titanate nanofibers synthesized by hydrothermal method are annealed in air and/or ammonia to achieve N-doped anatase fibers. Depending on the synthesis route, either interstitial N atoms or new N-Ti bonds appear in the lattice, resulting in slight lattice expansion as shown by XPS and HR-TEM analysis, respectively. These nanofibers were then used as support for Pd and Pt nanoparticles deposited with wet impregnation followed by calcination and reduction. In the hydrogen generation tests, the N-doped samples were clearly outperforming their undoped counterparts, showing remarkable efficiency not only under UV-B but also with UV-A illumination. When 100 mg of catalyst (N-doped TiO(2) nanofiber decorated with Pt nanoparticles) was applied to 1 L of water-ethanol mixture, the H(2) evolution rates were as high as 700 μmol/h (UV-A) and 2250 μmol/h (UV-B) corresponding to photo energy conversion percentages of ∼3.6 and ∼12.3%, respectively.

TiO 2 nanofibers decorated with Pt and Pd nanoparticles have been synthesized and studied in various photocatalytic processes. Excellent photocatalytic behavior in the decomposition of organic dyes in water, degradation of organic stains on the surface of flexible freestanding cellulose/catalyst composite films and in generation of hydrogen from ethanol using both suspended and immobilized catalysts are demonstrated. The performance of the nanofiber-based TiO 2 materials is competitive with-and in some cases outperforms-their conventional nanoparticle-based counterparts. In all cases, Pd-decorated TiO 2 nanoparticles and nanofibers proved to be more efficient than their Pt-based counterparts, which could be explained on the basis of the formation of nano-sized Schottky interfaces at the contacts between TiO 2 and metal nanoparticles. The feasibility of forming cellulose/catalyst composites provides a novel way of utilizing photocatalyst materials in large-area coatings and freestanding films.

Activated carbons were obtained from cocoa pod husk using two different initial particle sizes (ranges 0.25-0.50mm and 0.50-1.00mm), three chemical activation agents (K 2 CO 3 , KOH and ZnCl 2) and carbonization under nitrogen atmosphere during two hours at three different temperatures (500°C, 650°C and 800°C). The prepared activated carbons were characterized using Brunauer-Emmett-Teller (BET) and Langmuir surface areas, pore volume, average pore size, bulk density, moisture, ash content, and yield. The five best activated carbons were selected for further experiments according to the chemical activation agent used, high BET surface area, high pore volume and low ash content. Additionally, content of impurities, carbon content and FE-SEM micrographs were determined for these five best activated carbons. As adsorption tests were also carried out with these samples. Results of the experiments show that cocoa pod husk is a material that can be used to produce activated carbon by chemical activation and ZnCl 2 showed to be the best chemical activation agent based on the highest BET surface area (780 m 2 /g in the best case) and pore volume (0.58 m 3 /g in the best case), the lowest ash content (6.14% in the best case), and the highest carbon content (86.1% in the best case), compared with others chemicals. Carbons activated by ZnCl 2 are capable to adsorb As(V), getting As(V) removal levels up to 80% in less than 1 hour in the experimental conditions applied (initial pH 6-7, activated carbon concentration 0.1 g/l and 0.5 g/l, initial As concentration 100 ppb).

Three-dimensional carbon nanotube scaffolds created using micromachined Si/SiO2 templates are used as nanoparticulate filters and support membranes for gas-phase heterogeneous catalysis. The filtering efficiency of better than 99% is shown for the scaffolds in filtering submicrometer particles from air. In the hydrogenation of propene to propane reaction low activation energy of E(a) approximately 27.8 +/- 0.6 kJ x mol(-1), a considerably high turnover rate of approximately 1.1 molecules x Pd site(-1) x s(-1) and durable activity for the reaction are observed with Pd decorated membranes. It is demonstrated that appropriate engineering of macroscopic-ordered nanotube architectures can lead to multifunctional applications.