CHM2046 - Lecture Nanoscience Part 3

CHM2046 - Lecture Nanoscience Part 3 - Nanoscience and...

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Nanoscience and Nanotechnology PART 3 – Alternative Ways to Get to the Nano World Photolithography – Is a “top-down” approach for making nano-sized objects. “Top-down” means we start with big machines (top) and we use them to make small objects (bottom). What about a “bottom-up” approach? “Bottom-up” for a chemist means we start with the small particles (atoms and molecules) and we assemble them into much bigger nanoparticles and nanostructures.
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The Cell: “the Machinery of life” The truest example of “bottom up” nanotechnology is nature. Nature continuously constructs complex, efficient self- organizing and self-regulating molecular machinery and systems for all processes in living organisms. Photosynthetic Apparatus Membrane of the cell
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Brus (1984) Cram Lehn Supramolecular Chemsitry -- A nano-manipulation tool Chemistry Nobel Prize 1986 Curl Kroto Smalley Chemistry Nobel Prize 1996 C 60 : A nano-building block Synthetic Nanocrystals Chemists’ Campaign: “bottom-up” Colloidal Nanocrystals Nano-wire Bawendi Alivisatos Lieber file:/ D:/course/research_files/synthesis_files/synthfig10a_s.jpg Martin Mirkin Weller Heath Ijima Nanotube
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We will Focus on a Bottom-Up Nanoparticle Preparation Method Called “Template Synthesis” A great way to make nanowires and nanotubes. Can make these nanostructures out of any material. Dimensions can be controlled at will. Template synthesis is practiced in labs everywhere in the world and has become a workhorse nanomaterials fabrication technology.
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Scanning Electron Micrographs of a Nanopore Alumina Template Membrane Prepared in the Martin Lab Surface Image Very high density of monodisperse pores. Cross-Sectional Image Pore diameter can be controlled at will (10 nm to 200 nm). Template Synthesis Begins with a Nanopore Membrane or Other Solid
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The Pores in Such Membranes Can be Used as Templates to Prepare Nanomaterials Monodisperse solid nanowires and hollow nanotubes have been prepared. A very versatile method - Nanostructures composed of metals, polymers, semiconductors, other inorganic materials, carbons, etc. have been prepared. Composite nanostructures - Concentric tubular nanostructures. Segmented nanowires. Template synthesis is now one of the workhorse nanomaterials synthetic strategies and is practiced in laboratories throughout the world.
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Nearly Any Synthetic Method Used to Prepare Bulk Materials Can be Used with the Template Method to Make Nanomaterials Electrochemical metal deposition. Electroless metal deposition. Electrochemical polymerization. Chemical polymerization. Chemical vapor deposition. Sol-gel methods. Hydro-thermal methods. Center for Research at the Bio/Nano Interface
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A Simple Example – Metal Nanowires can be Made by Electrochemical “Template Synthesis” Metal electrode attached to template membrane Template membrane Pore Pore Pore Pore Electrochemical Gold Deposition (Long Time) Electrochemical Gold Deposition (Short Time) Au nanoparticle Au nanoparticle
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Electron Micrograph of Gold Nanowires Protruding from a Plasma-Etched Polymeric Template Surface
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High surface area electrode materials for high-power batteries
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This note was uploaded on 09/25/2010 for the course CHM 2046 taught by Professor Veige/martin during the Spring '07 term at University of Florida.

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CHM2046 - Lecture Nanoscience Part 3 - Nanoscience and...

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