Lecture 6 Synthesis - University Of Massachusetts Lowell

Self-assembly and Nanotechnology 10.524Lecture 6. Synthesis and Fabricationof NanomaterialsInstructor: Prof. Zhiyong Gu (Chemical Engineering& CHN/NCOE Nanomanufacturing Center)Self-assembly and Nanotechnology

Lecture 6: Synthesis and Fabrication of NanomaterialsTable of Contents Section I: Nanoparticlespsynthesisy(a) Some nanoparticle samples (Gold nanoparticles)(b) Case Study: Shaped Nanoparticles (nanocubes(nanocubes, etc) Section II: Carbon Nanotube synthesis Section III: Nanowires/nanorods(a) Nanoporous template: AAO membraneNanowire samples (Au(Au, NiNi, Cu)(b) Case study: Electrodeposition in nanoporous templatesSelf-assembly and Nanotechnology

Section I:S th i off NanoparticlesSynthesisNti lSelf-assembly and Nanotechnology

Growth of colloidal nanocrystals by reductionin the ppresence of surfactantsExample: Gold nanocrystalsGeneral Strategy¾ Metal precursor solution¾ Reducing Agent¾ Capping (stabilizing agent)¾ Solvent (heated)XX XXXXXXXX X Xtetrachloroauric acid (HAuCl4)boil withTrisodium citrateFrens, G. Controlled nucleation for the regulation of the particle size in monodisperse gold suspensions, Nature (1973),241(105), 20-2. J. Turkevich, et. al. Coagulation of Colloidal Gold. Discussions Faraday Soc. No. 11, 58 (1951).Self-assembly and Nanotechnology

Molecular surfactant templated growth of nanoparticlesSelf-assembly and Nanotechnology

Different solute interaction possibilities can occurNon-polar compoundPolar compoundAmphiphiliccompoundSelf-assembly and Nanotechnology

Synthesis of Nanoparticles Using Reverse MicellesAOT: Sodiumbis (2-ethylhexyl)suflosuccinate)Radius of micelle (nm) 0.15 [water] / [AOT]IsooctanewaterAOT moleculesMolar ratioShchukin, Dmitry G.; Sukhorukov, Gleb B. Nanoparticle synthesis in engineered organicnanoscale reactors. Advanced Materials (2004), 16(8), 671-682.Self-assembly and Nanotechnology

Nanoparticle Synthesis in Reverse MicellesTiO2 nanoparticle filmAOT: Reverse micelles (0.2 M AOT 0.4 M water in cyclohexane)Titanium isopropoxide Ti[OCH(CH3)2)]4 0.2 M added under vigorous stirringLangmuir, 13, 16, 1997Self-assembly and Nanotechnology

Nanoparticles StabilizationagainstgAggregationgg g((VDW force is high)g )Electrostatic(adsorption of ions)Coat particles withOrganic molecules / polymersCapping (stabilizing agent)e.g. Trioctylphosphine oxide (TOPO)Self-assembly and Nanotechnology

Nanoparticle Size Controlled by Ratio of Au(III) / citrateSize (nm)Reference: Chemical Physics Letters (2004), 395(4-6), 366-372Self-assembly and Nanotechnology

The diameter of gold nanoparticles determines the wavelengths of lightabsorbed.b b d ThThe colorsliin thithis didiagram illillustratet t thithis effect.ff tSelf-assembly and olor/9.html

Quantum DotsFluorescence induced by exposure to ultraviolet light in vials containing varioussized Cadmium selenide (CdSe) quantum dots.A quantum dot is a semiconductor nanostructure that confines the motion ofconduction band electrons, valence band holes, or excitons (pairs of conductionband electrons and valence band holes) in all three spatial directions.Self-assembly and Nanotechnology(Wiki)

Differentffsized quantum dot nanoparticles are shown above, firstfin ultravioletlight and then in ambient light. The length of the synthesis reaction determinesparticle size for CdSe, increasing from left to right. In colloidal suspension, thissemiconductor behaves in the same way as a metal.Self-assembly and olor/9.html

Shape Control over the Growth of Colloidal NanocrystalsA. Kinetic control: High energy facetsgrow faster than low energy facetsB. Kinetic shape control throughselective adhesionC. Intermediate energy facet eliminateshigh energy facet.D. Controlled branching of nanocrystalsY. Yin and A. P. Alivisatos, Nature, (2005) 664-670Self-assembly and Nanotechnology

Case Study I:ShShapedd NanoparticlesNti l - NanocubesNbSelf-assembly and Nanotechnology

Shaped NanoparticlesS h i l vs. shapedSphericalhd nanoparticlesti lNovel properties: size and shape dependentoptical, electrical, etc.Several examples Younan XiaXia’ss groupgroup, U WashingtonNanocubes: Science, 2002, 298, 2176-2179Ag nanocubes Catherine J. Murphy’s group, U South CarolinaNanorods: J. Phys. Chem. B 2005, 109, 13857-13870Au nanoparticles A Paul Alivisatos’s group, UC BerkeleyBranched nanocrystals: Nature 2005,2005 437,437 664-670664 670Tetrapod-shaped CdSeSelf-assembly and Nanotechnology

Shaped Nanoparticles – Polyol SynthesisSolution-phase synthesisIncluding: metal precursor, solvent, reducing agent, capping agent, etc.Capping agents: surfactants or polymers, modifying the kinetics of atomsassembly/growth to generate shapesP l l method:Polyolth d easy andd efficientffi i t methodth dSolvent: ethylene glycolAlso as a reducingg agentgwhen heatedCapping agents: polymers mostly usedPurposes: Self-assembly or directed assembly to create 1D, 2D, and 3D structures Self-assembly with polymers or block copolymers to obtain novel nanocompositesSelf-assembly and Nanotechnology

Shaped Nanoparticles – Some Preliminary ResultsSEM images of Ag nanoparticles using poly(vinyl pyrrolidone) (PVP)SEM imagesioff AgA nanoparticlesti l usingi BlBlockk copolymerslPluronic blockcopolymersPEO-PPO-PEOSelf-assembly and Nanotechnology

Shaped Nanoparticles – NanocubesSEM images of Ag nanoparticles using poly(allylamine hydrochloride) (PAH)SphericalZoom inSelf-assembly and NanotechnologyCubesZoom out

Section II:S th i off CarbonSynthesisC b NNanotubest bSelf-assembly and Nanotechnology

Carbon Nanotube: A Form of Carbon(metastable)Graphite (stable)Bucky ball(metastable)Nanotube rolled sheetof ggraphitepSmalley & Kroto, 1997 NobelHelical Microtubules of graphitic Carbon, Ijima, S, Nature, 354 (6348): 56-58 NOV 7 1991Cited: 4000 timesReview on Nanotubes:Accounts of Chemical Research (2002), 35(12). Entire issue is based on Nanotubes.Dai, Hongjie. Carbon nanotubes: opportunities and challenges.Self-assembly and NanotechnologySurface Science (2002), 500(1-3), 218-241.

Different Types of NanotubesZig-ZagArmchaira1 zig zag vectora2 reflection over armchair lineChiralSelf-assembly and Nanotechnology

Different Types of NanotubesThe (n,m) nanotube naming schemecan be thought of as a vector (Ch) in aninfinite graphene sheet that describeshow to 'roll up' to graphene sheet tomake the nanotube. T denotes the tubeaxis, and a1 and a2 are the unit vectorsof graphene in real space. It is basedupon similar diagrams found in theliterature (for instance, Odom et al.Topics Appl. Phys., 2001, 80, 173).Self-assembly and NanotechnologyarmchairZig-ZagChiralScience,, 297,, 2 Augg 2002TEM Chiral

Single Wall and Multi Wall NanotubesUp to cm longSWNT(singleWall nanotube)Diameter 1.4 nmMWNT(multiwall)Diameter 10-20 nmMust read Paper:Iijima, Sumio. Carbon nanotubes: past, present, and future. Physica B: Condensed Matter (2002), 323, 1-5.Self-assembly and Nanotechnology

Methods for Fabricating Nanotubes Arc Vaporization Laser Vaporization CVD FlameSelf-assembly and Nanotechnology

Arc Discharge 1mm spacedcarbon electrodesInertAtmosphere(0.6 atm)Metal doped electrodes (Fe(Fe, CoCo,Ni, Mo): SWNTPure Graphitic electrodes: MWNT(other fullerenes etc)DC ((20 V, 100 A))Generates an arcDuring this process, the carbon contained in the negative electrode sublimatesbecause of the high temperatures caused by the discharge. Because nanotubes wereinitially discovered using this technique, it has been the most widely used method ofnanotube synthesis.The yield for this method is up to 30 percent by weight and it produces both singleand multiwall nanotubes, however they are quite short (50 microns)Self-assembly and Nanotechnology

CVD: Metal CatalystsHiPco: COHiPCO, FFe(CO)(CO)5Commercial Process97% Pure, 450 mg /hr C based gas (acetylene, ethylene, methane) Catalyst (Fe,(Fe Co,Co Ni) Temperature 700-1000 CSelf-assembly and Nanotechnology

Laser Ablation, pulsed laser, 500 Torr Ar.M h iMechanismAblAblation,tiarc didischarge:hStill CControversialti l Atomize Carbon (Explode or Dissociate on Metal) Preclude initial recombination (metal-C bond, high energy) Confinement (Prevent over expansion, Background Pressure Key * Notedeposition is not in vacuum) Cooling (crucial for SWNT, MWNT) (In a metal Dissolution to form asupersaturated solution) sp2 hybridization, sheet bends to reduce dangling bonds (high energy)FoldingHighDanglingbondsIn the laser ablation process, a pulsed laser vaporizes a graphite target in a hightemperaturepreactor while an inert ggas is bled into the chamber. The nanotubesdevelop on the cooler surfaces of the reactor, as the vaporized carbon condenses. Awater-cooled surface may be included in the system to collect the nanotubes.Self-assembly and NanotechnologyJournal of Cluster Science (2003), 14(2), 135-185.

Role of Catalytic Particles in Nanotube GrowthExtrusion or Root GrowthCnHmTip GrowthCnHm C H2Explains Hollow TubeSelf-assembly and Nanotechnology

Purification to get carbon nanotubes of precise composition and size Oxidation: Damage to SWNT (closed structure less reactive) lessthan other carbon / metal compounds Acid treatment, Ultrasonication (Metal removal) Magnetic removal of catalysts Microfiltration (SNWT trapped),trapped) fullerenes solvated in CS2 Functionalization, Cutting using fluorination and pyrolysis Chromatography (HPLC-SEC)Self-assembly and Nanotechnology

Section III:S th i off NanowiresSynthesisNiSelf-assembly and Nanotechnology

Most commonly used methodsCVD (Chemical Vapor Deposition)Solution phase synthesisElectrodepositionpSelf-assembly and Nanotechnology

Vapor Liquid Solid (VLS) growth (in CVD)I : Metal catalyst reacts with vapor of Ge (from the decomposition of GeI2)II: Au and Ge form a liquid eutectic when temp above (361 C)III: Droplet becomes supersaturated in Ge, Ge starts to precipitate on liquid Au,at the solid liquid interface.R. S. Wagner, W. C. Ellis, Applied Physics Letters, 1964, 4, 89;Y. Xia et al, Advanced Matierals, 2003, 15, 353-387.Self-assembly and Nanotechnology

Example: Birth of a Ge Nanowire from an Au Catalyst ParticleAu catalyst GeI2 vapourSEM images of Ge nanowiresY. Wu, P. Yang, JACS 2001, 123, 3165Self-assembly and Nanotechnology

Case Study II:Electrodeposition of Nanowires/Nanorodsin Nanoporous TemplatesLab Session II (after spring break)Self-assembly and Nanotechnology

Promising Nano-Building Blocks – Nanowires (Nanorods)Nanoparticles(1-100nm)Kovtyukhova & Mallouk,Chem. European J.,2002, 8, 4354-4363Nanowires (nanorods)Anisotropic nanoparticlesSurface functionalizationAssembly/integrationIntegrated structures or devicesNNanoporousmembranesb((aluminal i or polycarbonate)lbt )Mn n e MMn An-ElectrolytesElectrodepositionlengthg 50 µmµReductiondiameter (d) 15-200nmTemplates commercially available,available and easy to makeVery large scale production (109-1010 wires/cm2)Relatively easy to fabricate and very good to pattern

Fabrication of Large-scale One- and Multi-component NanowiresEvaporateProcess flowElectroplateElectrolyticsolutions(Mn )AgDissolveEtchtemplateAgLayer 2Layer 1Free standing nanowiresNanowires with one- and multi-component segmentsGold-Nickel-gold(d 200nm)500nmOne-component nanowires(gold nanowires, d 50nm)Multi-component nanowiresGu, Ye, Gracias. Journal of Materials (JOM) 2005, 57, 60-64

Hybrid Nanowires with Controlled Size and FunctionalityNanowires with different diameters100nm100nmAu nanowire, d 15nmAu nanowire, d 50nmSymmetrical and asymmetrical nanowires100nm200nmInorganic-organic nanowire: metal-polymer nanowiresP lPolypyrrolel200nmAu-Polypyrrole nanowire, d 200nmNNanowiresiwithith ffunctionaltil segmentstNWith ferromagnetic segments (e.g., Nickel)N200nm200SWith sensor segmentsAnneal200nmTin (Sn)NSNidSL dLNNiSL dSn SnO2: excellent sensor materials

Summaryy and pperspectivep Section I: Nanoparticles synthesis Section II: Carbon Nanotube synthesis Section III: Nanowires/nanorods Molecular based nanomaterials(organic molecules, polymers, ) Bio-related nanomaterials and nanostructures(DNA, peptide, virus, etc) New nano-building blocks Self-assembly and Nanotechnology

Lecture 6: Synthesis and Fabrication of Nanomaterials Section I: Nanoparticles synthesis Table of Contents py (a) Some nanoparticle samples (Gold nanoparticles) (b) Case Study: Shaped Nanoparticles (nanocubes etc)(b) Case Study: Shaped Nanoparticles (nanocubes, etc) Section II: Carbon Nanotube synthesis Section III: Nanowires/nanorods