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3439 Nanochemistry Willkommen Welcome Bienvenue 3439 Nanochemistry Introduction Andreas Borgschulte (andreas.borgschulte@empa.ch) CHE729.1 Mi. 10:15-12:00 Contents of this lecture Introduction: We are assembled nano-machines! Nanotechnology History, Definition Visualization of nanostructures Size dependent properties Preparation of nano structures Bottom-up approach top-down approach theory Some applications colloids Hydrogen storage catalysis membranes cell biology Nanotoxicity What is NOT Nanochemistry? What are the scientific questions to be addressed? Definition / History Nanotechnology is the manipulation of matter on an atomic and molecular scale. Generally, nanotechnology works with materials, devices, and other structures with at least one dimension sized from 1 to 100 nanometres. The scanning tunneling microscope, an instrument for imaging surfaces at the atomic level, was developed in 1981 by Gerd Binnig and Heinrich Rohrer at IBM Zurich Research Laboratory K. Eric Drexler developed and popularized the concept of nanotechnology and founded the field of molecular nanotechnology. In 1979, Drexler encountered Richard Feynman's 1959 talk There's Plenty of Room at the Bottom. Ref. wikipedia Liquids/gases Pyrite FeS2 1023 Perovskite CaTiO3 3-mm diamond in eclogite graphene Diamond Graphite Fullerene Carbon nanotubes • Allotrope of carbon • Graphite sheet rolled into a tube • 50,000x smaller than human hair • Members of fullerene family (including buckyballs) www.ewels.info/img/science/nano.html Single-walled nanotubes • Capped or uncapped • All covalent sp2 bonding • Metallic conductors or semiconductors • Bundles • Defects – points for reaction Multi-walled nanotubes • 63GPa tensile strength (steel 1.2GPa) • Inner tubes slide without friction http://www.msm.cam.ac.uk/polymer/research/nanointroCNT.html Graphene – the new Wonder material Strength of graphene Graphene has a breaking strength of 42N/m, which is more than 100 times stronger than steel Electrical conductivity of graphene The sheet conductivity of a 2D material is given by . The mobility is theoretically limited to μ=200,000 cm2V−1s−1 by acoustic phonons at a carrier density of n=1012 cm−2. The 2D sheet resistivity, also called the resistance per square, is then 31 Ω. Our fictional hammock measuring 1m2 would thus have a resistance of 31 Ω. σ=enμ Using the layer thickness we get a bulk conductivity of 0.96x106 Ω-1cm-1 for graphene. This is somewhat higher than the conductivity of copper which is 0.60x106 Ω-1cm-1. Thermal conductivity The thermal conductivity of graphene is dominated by phonons and has been measured to be approximately 5000 Wm−1K−1. Copper at room temperature has a thermal conductivity of 401 Wm−1K−1. Background information Noble price in Physics 2010 https://www.nobelprize.org/nobel_prizes/physics/laureates/2010/advanc ed-physicsprize2010.pdf Picture credit: Alexander Aius, Wikipedia https://www.youtube.com/watch?v=O1WpE5ntqbQ Massless Dirac quasiparticles in graphene The intrinsic resistivity of graphene sheets would be 10−6 Ω⋅cm. This is less than the resistivity of silver. Electrons behave like a wave… 1 ∗ ⋯ 2 Akin Akturk and Neil Goldsman, J. Appl. Phys. 103, 053702 (2008); A. H. Castro Neto et al., Rev. Mod. Phys., Vol. 81, 109 (2009) Theory 2 M. D. Hanwell V R r (r) (r), 2m Schrödinger equation solvable for limited number of atoms N < 103 Nanomaterials 102 … 105 atoms Band structure in crystalline solids: Bloch functions N ~ 1023 (r R) (r) 0 exp2i / a k = 0 E(k) k = 0 E0 k = /a Oleg Shpy k = 0 k = /a Nanoribbons for graphene transistors Baringhaus, J.; Ruan, M.; Edler, F.; Tejeda, A.; Sicot, M.; Taleb-Ibrahimi, A.; Li, A. P.; Jiang, Z.; Conrad, E. H.; Berger, C.; Tegenkamp, C.; De Heer, W. A. Nature 506, 349–354 (2014) J. Cai, P. Ruffieux, R. Jaafar, M. Bieri, T. Braun, S. Blankenburg, M. Muoth, A.P. Seitsonen, M. Saleh, X. Feng, K. Müllen, R. Fasel, Nature, 466, 470-473 (2010) Memory Chip Catalysis of hydrogen combustion H combustion needs 600°C without, H 2 M 2H *M 2 proceeds at RT with Pt catalyst H + H (E = 2.4 eV) 2H 2 O2 4H *2O* 2H 2O Surface Reaction Pt-nano particles on a ceramics Catalytic hydrogen burner (Empa 2009) Döbereiner Cigar lighter (1823) Hydrogen dissociation on d-metals Solid–liquid interface: Electrochemical Double layer with ze kBT distance x exp x Debye length potential 1 0 r kBT 0.34 D 2 nm 2N Ae I Imol/l + water + - The mystery of electrochemistry + - + 0 0 + solid - - - + + T. Cosgrove, Colloid Science, Principles, methods, and applications, Wiley 2010; The hydrogen electrode: Butler‐Volmer equation H2 EU U / kT j k0 ' e Pt-electrode EU / kT j k0 1 e U U chemical potential H H O-H+ 2 E e- e- + H + H2O H2O-H H+ H3O+ + H H2O-H reaction coordinate H2 H H O-H+ 2 log j log j0 b()U Marcus‐Theory of the charge transfer metal metal sphere GG sphere free energy free energy reaction ecoordinate R.A. Marcus Nobel price 1992 1 1 1 1 2 G f (e) e electrostatic r R opt stat contribution 0 2 G + chemical G 0 Ion 4 contribution G Transition-state Theory 2 G0 k(T ) exp 4k T B Experimental confirmation of Marcus theory G reactant / Product I/II/III Variation of G0 at constant 0 GI 0 0 GII 0 GIII q=e 2 G0 k(T ) exp 4k T B R. Marcus, Angew. Chem. lnt. Ed. Engl. 1993, 32. 1111 Electron transfer between molecules ~ Electrodes ∆ ln ∝ ln ∝ ln 1E13 4∙ 100 2 1E12 ∆ ) ) ∝ 2 -1 10 inverted region 2 1E11 k (s j (mA/cm 1 1E10 1E9 0.1 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.5 0.4 0.3 0.2 0.1 0.0 -0.1 G (eV) U = G (eV) B - + + S. Murphy, et al., J. Org. Chem., 60, 2411, 1995; M. H. Miles, et al. J. Electrochem. Soc., Bd. 123, p. 332, 1976. Reorganization energy The inner part corresponds to the energy v s cost due to geometry modifications to go from a neutral to a charged geometry and vice versa. 2 G0 k(T ) exp The outer part corresponds to the energy 4k T B cost from the solvent response. 2.2 2.0 1.8 1.6 voltage (V) 1.4 0 50 100 150 200 -2 of the first electron transfer only ~0.25 eV current density (mA cm ) out of an overall excitation energy of 1.38 eV R. Marcus, Angew. Chem. lnt. Ed. Engl. 1993, 32. 1111 Mitochondria_360p Kopie.mov Biology takes place in nano-structures membrane thickness ~10 nm mitochondrium Simplified spatial scheme of photosynthesis stroma NADPH ADP + NADP +P H + H+ ATP HEC P680/ PQ cytochrome P700 Q /Q OEC PC ATP synthase 3H+ 2 H2 O + lumen 4H + O2 Alkaline water electrolyzers: electrolyte/membrane + O2 H2 - gas separation by membranes l = 1mm Lurgi, Zdansky-Lonza pressure electrolysis: (a) Bipolar electrodes, dimple plate cell partition; (b) Pre-electrodes in the form of nets on both sides of asbestos diaphragms ; (c) Asbestos diaphragms; (d) Cell frame; (Häussinger P., et al., 2006) Silicates: crystal structure O Main unit for all silicates : Si Quartz SiO2 SiO4 SiO4 BO SiO4 SiO4 SiO4 SiO4 SiO4 SiO4 Olivine, (Mg,Fe) SiO ) Mg1 Mg1 2 4 Mg1 Mg1 Mg1 Mg1 Mg1 Mg1 Mg1 Mg1 SiO4 SiO4 SiO4 SiO4 Mg2 Mg2 Mg2 Mg2 Mg2 Mg2 NBO Mg2 Mg2 Mg2 Mg2 Top: SEM image SiO4 SiO4 SiO4 SiO4 Mg1 Mg1Mg1Mg1Mg1 Mg1 Mg1Mg1Mg1Mg1 Mg1 of a chrysotile, SiO4 SiO4 SiO4 SiO4 Mg Si O (OH) , Mg2 Mg2 3 2 5 4 one of the Pyroxene, (Fe, Ca,Mg) Si O asbestos 2 2 6 minerals) fiber Chrysotile bundle. Bottom: (Asbestos):Mg3Si2O5(OH)4 through the fiber bundle (Ref: Grobety et al.,) http://webmineral.com/ Betechtin, Mineralogy, 1951 Nano-structured membranes have superior properties However, the physical shape of material can seriously affect its toxicity Asbestos Serpentine – flat sheets of atoms, harmless Chrysotile – nano-scale tubes One should treat these new nano-materials with caution http://whatisasbestosis.com/risks-of-asbestos-exposure/ Nanotoxicity ‘frustrated’ phagocytosis of carbon nanotubes by peritoneal macrophages. Asbestos nano fibres cause lung cancer C. A. Poland et al. nature nanotechnology 3, 423 (2008) Empa Nanosafety Research: Human macrophage exposed to Hematite-Nano band-aid coated with Ag particles (70 nm). SEM nano particles (Empa) Nanotoxicity of Au-particles All nanoparticles within the 2–100 nm size range were found to alter signalling processes essential for basic cell functions (including cell death), 40- and 50-nm nanoparticles demonstrated the greatest effect. W. Jiang et al. nature nanotechnology 3, 145 (2008) 10-2m 10mm 10-3m 1mm Red blood cells (~2-5μm) 10-4m 0.1mm Virus Hair (~60-120μm) (10-300nm) 10-5m 0.01mm 10-6m Infrared0.001mm, Microwave 1μm (1000nm) Bio-nano machines (<10 nm) Ag-nanoparticles 10-7m 0.1μm (100nm) (1-100 nm) 10-8m Ultraviolet 0.01μm (10nm) 10-9m 1nm Buckyball X-ray Gold atom DNA (~1nm) 10-10m 0.1nm Courtesy Zoe (135pm) (~2nm diameter) Schnepp Colloids colloids, (micro-) emulsion phase diagrams, stability Ostwald ripening, coalescence electrochemical double layer, zeta-potential rheology Aerosols Tyndall effect pics_: Wikipedia Wave length of visible light: 400 – 800 nm Can we see nano structures? JEOL 2200FS TEM/STEM High-resolution and analytical STEM/TEM Tomography Point resolution TEM 0.23 nm Resolution STEM 0.16 nm Ernst Karl Abbe optics: d ~ 200 nm electron microscope d < 1 nm d 2NA resolution limit of the microscope Nano-structure of a Hydrogen combustion catalyst A. Fernández et al., Appl. Catal. B (2016) Scanning Probe Microscopy Measuring physical interaction (z) Use it as a control parameter to map the surface Force (AFM) Tunneling current (STM) Capacity (SCAM) Light (SNOM) Thermal properties Tunneling current in STM I - + U - - surface tip + + R s vacuum metal metal E d F 1st images of Si (111): Binnig and Rohrer Atomic resolution of 1982 ||2 (no atoms!) Atoms at the surface of a carbon nanotube Size dependent properties Size and surface area effects 1 nm – 100 nm Fundamental materials properties remain the same but size, shape and surface area alter some behaviors such as work function, solubility, chemical potential, contaminate sorption Critical Size and Characteristic Length Scale Interesting or unusual properties because the size of the system approaches some critical length (includes quantum effects).
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