Jyri-Pekka Mikkola

Nitrogen-Doped Anatase Nanofibers Decorated with Noble Metal Nanoparticles for Photocatalytic Production of Hydrogen

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.

CHAPTER 1:The Biorefinery and Green Chemistry

If the living standards of western societies are to be maintained while those of the developing world change at their current tempo, then, because of the depletion of fossil resources and concerns about the environment, the concept of biorefining, following the principles of green chemistry as well as sustainability, will surely become more and more important in the future. This chapter introduces the concept of what biorefineries are and discusses their sustainability, taking into account green chemistry and engineering aspects. As well as a brief history, todays situation in the biorefining industry is covered with several examples. Also, the directions for the future biorefineries are considered.