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gened.emc.maricopa/bio/BIO181/BIOBK/BioBookCELL2.html

Science Imitates Life. Liver Cell (TEM x9,400). Lily Parenchyma Cell (cross-section) (TEM x7,210). http://gened.emc.maricopa.edu/bio/BIO181/BIOBK/BioBookCELL2.html. Quantum Dots. http://web.mit.edu/chemistry/nanocluster/home.html. Nanotechnology: Nano-gears. http://nanozine.com/nanogear.htm.

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gened.emc.maricopa/bio/BIO181/BIOBK/BioBookCELL2.html

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  1. Science Imitates Life Liver Cell (TEM x9,400) Lily Parenchyma Cell (cross-section) (TEM x7,210) http://gened.emc.maricopa.edu/bio/BIO181/BIOBK/BioBookCELL2.html

  2. Quantum Dots http://web.mit.edu/chemistry/nanocluster/home.html

  3. Nanotechnology: Nano-gears http://nanozine.com/nanogear.htm

  4. solid state molecular Nanoscale Metallic Particles • Chemical and Physical Properties • intermediate between the bulk metal and molecular clusters • properties effected by large fraction of surface atoms • morphology • electronic structure (quantum confinement) Scheme adapted from Schmid, G. In Clusters and Colloids; Schmid, G., Ed.; VCH, Weinheim,1994.

  5. 8 N = 4096 n = 1352 N = 4096 n = 2368 8 N = 4096 n = 3584 N = total atoms; n = surface atoms Surface Area Scheme adapted from Schmid, G. In Clusters and Colloids; Schmid, G., Ed.; VCH, Weinheim,1994.

  6. CH2=CH2 CH3-CH2=CH2 +CH2 +CH2 -CH2 -CH2 -Hydrogen Elimination CH2 -H -H CH2 CH2 (CH2)2 Migratory Insertion -Hydrogen Elimination ... +CH3 -CH3 CH3 H CH2 +H +H +H H + CH + C -H CH4 H2 O CO -Hydrogen Elimination Heterogeneous Catalysis • High surface area supports • Maximize metal surface area • Bimetallic: improve selectivity and activity • Electronic and structural modifiers Scheme adapted from: http://www.chem.northwestern.edu/brochure/stair.html

  7. Supported Metal Nanoparticles • Direct Methanol Fuel Cell (DMFC) • methanol electroxidation • rapid degradation of anode catalyst • performance • current state-of-the-art catalyst: • supported Pt, Pt-alloys (Pt-Ru) http://www.methanol.org/images/schema_fuel.jpg

  8. a b Cyclic Voltammetry Sample cyclic voltammograms of a Pt electrode (3 mm): a) 0.5 M H2SO4; b) 0.5 M H2SO4 + 4 M CH3OH.

  9. n ‘Small’ ‘Large’  c(n) Specific effects 5.5 Smooth size effects 5.0 4.5 IP (ev) n-b 4.0 Bulk value c() 3.5 3.0 0 10 5 15 20 25 n Size Effects in Nanoscale Materials Ionization Potential as a function of particle size. Adapted from: Jena, P; Khanna, S.N.; Rao, B.K. Physics and Chemistry of Finite Systems: From Clusters to Crystals (NATO-ASI Series). 1992 (Deventer: Kluwer). Woltersdorf, J.; Nepijko, A.S.; Pippel, E. Surf. Sci.1968, 12, 134.

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