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22-P-08-Formation of carbon nanotubes on various molecular sieves supported metal oxides
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22 - A d v a n c e d Materials (Thursday) 22-P-06 - Tailored generation of titanium oxide species within porous Si-MCM-41 P. Prochnow (a), G. Schulz-Ekloff (a), M. Wark (a,b), J.K. Thomas (b), A. Zukal (c) and J. Rathousky (c) a Institute of Applied and Physical Chemistry, University of Bremen, Germany, [email protected]; b Department of Chemistry and Biochemistry, Notre Dame University, USA; c J. Heyrovsky Institute of Physical Chemistry, Prague, Czech Republic It is elaborated, that the generation of titanium oxide species of tailored and uniform size into Si-MCM-41 as host material does not only depend on the amount of titanium compounds added in one step, but also on the repeated addition and hydrolysis of the titanium compound in consecutive steps. Anatase nanoparticles of a well-defined size of up to 3 nm, Ti(IV) oxide oligomers and mononuclear Ti(IV) oxide species, respectively, were generated without a substantial enrichment of titanium oxide particles on the extemal surface of the Si-MCM-41 host. Depending on the size and content of the Ti(IV) oxide species, the fluorescence of co-impregnated dye molecules was statically quenched to varying extent.
22-P-07 - Optical switching with photochromic dye molecules encapsulated in the pores of molecular sieves by in-situ synthesis C. Schomburg (a), D. W~hrle (a), G. Schulz-Ekloff (b) and M. Wark (b) a Institute of Organic and Macromolecular Chemistry, University of Bremen, Germany ; b Institute of Applied and Physical Chemistry, University of Bremen, Germany, mwark@chemie, uni-bremen,de Spiropyran or its configurational isomers (merocyanines), respectively, are incorporated in the supercages of faujasite (NAY, HY and DAY) by in-situ synthesis. Luminescence spectra of the colored isomers indicate the non-aggregated incorporation of merocyanine forms. Photochromism experiments exhibit high quantum yields for the photoinduced switching between the different configurational isomers. The strong retardation of the thermal relaxation rate from the cis isomer to the trans isomer in the faujasite hosts is attributed to an increase of the rotation barriers by the imposed spatial restrictions. A strongly increased stability towards photobleaching is found with respect to spiropyrans stabilized in organic polymers or SiO2 based MCM-41 matrices.
22-P-08 - F o r m a t i o n of carbon nanotubes on various molecular sieves supported metal oxides A.M. Zhang, Q.H. Xu, J.J. Zhao and J.M. Cao Department of Chemistry, Nanjing University, Nanjing, 210093, P. R. China The carbon nanotubes were formed on metal oxide-supported zeolite by the decomposition of acetylene hydrocarbon at 700~ The optimum reaction conditions of growth of nanotubes on various molecular sieve catalysts, including Y, A, MOR, ZSM-5 and MCM-41, were studied. Fe/Co-supported Y zeolite catalyst may be the best catalyst for growth of nanotubes in them. Masses of carbon nanotubes with uniform diameter of about 30 nm were obtained over pretreated Y zeolite. The states of iron in Fe-supported Y catalyst measured by M6ssbauer spectrum during three stages of original, hydrogen reduced and catalytic synthetic nanotubes indicated that the hydrogen generated during the reaction is enough to reduce the Fe(III) to sub-valence active state. The nanotubes of larger diameter may be as the template of GaN growth.
22 - A d v a n c e d Materials (Thursday) 22-P-06 - Tailored generation of titanium oxide species within porous Si-MCM-41 P. Prochnow (a), G. Schulz-Ekloff (a), M. Wark (a,b), J.K. Thomas (b), A. Zukal (c) and J. Rathousky (c) a Institute of Applied and Physical Chemistry, University of Bremen, Germany, [email protected]; b Department of Chemistry and Biochemistry, Notre Dame University, USA; c J. Heyrovsky Institute of Physical Chemistry, Prague, Czech Republic It is elaborated, that the generation of titanium oxide species of tailored and uniform size into Si-MCM-41 as host material does not only depend on the amount of titanium compounds added in one step, but also on the repeated addition and hydrolysis of the titanium compound in consecutive steps. Anatase nanoparticles of a well-defined size of up to 3 nm, Ti(IV) oxide oligomers and mononuclear Ti(IV) oxide species, respectively, were generated without a substantial enrichment of titanium oxide particles on the extemal surface of the Si-MCM-41 host. Depending on the size and content of the Ti(IV) oxide species, the fluorescence of co-impregnated dye molecules was statically quenched to varying extent.
22-P-07 - Optical switching with photochromic dye molecules encapsulated in the pores of molecular sieves by in-situ synthesis C. Schomburg (a), D. W~hrle (a), G. Schulz-Ekloff (b) and M. Wark (b) a Institute of Organic and Macromolecular Chemistry, University of Bremen, Germany ; b Institute of Applied and Physical Chemistry, University of Bremen, Germany, mwark@chemie, uni-bremen,de Spiropyran or its configurational isomers (merocyanines), respectively, are incorporated in the supercages of faujasite (NAY, HY and DAY) by in-situ synthesis. Luminescence spectra of the colored isomers indicate the non-aggregated incorporation of merocyanine forms. Photochromism experiments exhibit high quantum yields for the photoinduced switching between the different configurational isomers. The strong retardation of the thermal relaxation rate from the cis isomer to the trans isomer in the faujasite hosts is attributed to an increase of the rotation barriers by the imposed spatial restrictions. A strongly increased stability towards photobleaching is found with respect to spiropyrans stabilized in organic polymers or SiO2 based MCM-41 matrices.
22-P-08 - F o r m a t i o n of carbon nanotubes on various molecular sieves supported metal oxides A.M. Zhang, Q.H. Xu, J.J. Zhao and J.M. Cao Department of Chemistry, Nanjing University, Nanjing, 210093, P. R. China The carbon nanotubes were formed on metal oxide-supported zeolite by the decomposition of acetylene hydrocarbon at 700~ The optimum reaction conditions of growth of nanotubes on various molecular sieve catalysts, including Y, A, MOR, ZSM-5 and MCM-41, were studied. Fe/Co-supported Y zeolite catalyst may be the best catalyst for growth of nanotubes in them. Masses of carbon nanotubes with uniform diameter of about 30 nm were obtained over pretreated Y zeolite. The states of iron in Fe-supported Y catalyst measured by M6ssbauer spectrum during three stages of original, hydrogen reduced and catalytic synthetic nanotubes indicated that the hydrogen generated during the reaction is enough to reduce the Fe(III) to sub-valence active state. The nanotubes of larger diameter may be as the template of GaN growth.