TEXT-BOOK EXAMPLES! Overview of carbon nanoforms!

Transcription

1 Nanomaths 2012 TEXT-BOOK EXAMPLES! Overview of carbon nanoforms! (PART I) Irene Suarez-Martinez! Nanochemistry Research Institute, Curtin University, Perth, Western Australia!

2 every element says something to someone (something different to each) [ ] one must perhaps make an exception for carbon, because it says everything to everyone. Primo Levi in The periodic table

3 Carbon chemistry! - 1s 2, 2s 2, 2p 2 : 4 valence electrons for bonding - Possible hybridisation of s and p orbitals : sp n, n = 1, 2, 3 C C sp 3 hybridisation: tetrahedral with angle C=C sp! hybridisation: trigonal with angle 120 C!C sp hybridisation: linear with angle 180 Bond Hybridation Coordination Length (A) Energy (KJ/mol)

4 Allotropes of Carbon (bulk

5 Allotropes of Carbon! Carbon Nanoforms

6 nano 6 Carbon Nanotubes Fullerenes Graphene

7 nano 6 Carbon Nanotubes Fullerenes Graphene

8 Fullerenes! DEFINITION: Family of closed cage molecules exclusively made of carbon atoms. Fullerenes were discovered in 1985 and their discover was awarded the Nobel prize in Chemistry to Robert Curl, Harry Kroto and Richard Smalley in 1996 Fullerenes are considered as the launch of the revolution in carbon nanomaterials and the birth of a whole new area of chemistry.

9 Fullerenes! DEFINITION: Family of closed cage molecules exclusively made of carbon atoms. C 60 is the Buckminsterfullerene IUPAC name: (C 60 -I h ) [5,6] fullerene Richard Buckminster Fuller

10 R. Buckminster Fuller s patent for the geodesic dome.

11 R. Buckminster Fuller s patent for the geodesic dome.

12 The Eden Project, Cornwall, UK

13 Buckminster Fuller On the cover of Time magazine..look at his head

14 Fullerenes! DEFINITION: Family of closed cage molecules exclusively made of carbon atoms. C 60 is the Buckminsterfullerene IUPAC name: (C 60 -I h ) [5,6] fullerene 12 pentagons + variable number hexagons Leonhard Euler's theorem on the relation between the numbers of faces, vertices and edges in polyhedra. V-E+F=2 (condition for closed cage) V = vertices E = edges F = faces If only all pentagons and hexagons: 12 pentagons C60 = 12 pentagons + 20 hexagons C70 = 12 pentagons + 25 hexagons Isolated pentagon rule

15 Fullerenes! DEFINITION: Family of closed cage molecules exclusively made of carbon atoms. C 60 is the Buckminsterfullerene IUPAC name: (C 60 -I h ) [5,6] fullerene All atoms are equivalent (quasi-sp 2 ) Two types of bonds: 1) pentagon-hexagon: single-character (1.458 A) 2) hexagon-hexagon: double-character (1.401 A) Schlegel representation

16 Fullerenes! DEFINITION: Family of closed cage molecules exclusively made of carbon atoms. C 60 is the Buckminsterfullerene IUPAC name: (C 60 -I h ) [5,6] fullerene All atoms are equivalent (quasi-sp 2 ) Two types of bonds: 1) pentagon-hexagon: single-character (1.458 A) 2) hexagon-hexagon: double-character (1.401 A) Schlegel representation

17 Fullerenes! DEFINITION: Family of closed cage molecules exclusively made of carbon atoms. C 60 is the Buckminsterfullerene IUPAC name: (C 60 -I h ) [5,6] fullerene All atoms are equivalent (quasi-sp 2 ) Two types of bonds: 1) pentagon-hexagon: single-character (1.458 A) 2) hexagon-hexagon: double-character (1.401 A)

18 Fullerene Synthesis!! Arc-electric (two graphite rods, sharpened, electric spark between tips)!! Laser ablation of a graphite powder target under flowing Ar gas!! Direct formation from graphene!

19 Cuvilin et al. Nature Chemistry vol 2, Pages: (2010)

20 Applications of fullerene! Organic solar cells D. Guldi, Pure Appl. Chem. 75, 1069 (2003) Skin creams The company claims that Fullerene C-60 is 100 times more effective than Vitamin E in the same concentration for neutralizing free radicals

21 Some genuine medical ʻproʼs!! Water soluble fullerenes (functionalised) have shown promise as:!! Anti-cancer agents!! Anti-HIV agents!! Protective agents against free-radical induced liver damage!! They are good free radical scavangers and antioxidants! The exponential increase in patent filing and publications [in medicine / pharmaceuticals] indicate growing industrial interest that parallels academic interest. The discovery of fullerenes has been compared to the discovery of benzene by many researchers. T. Seema, R. Mehta, Ind. J. Pharm. Sciences, 68 (1), 13 (2006).

22 .. But, excited states! T. Seema, R. Mehta, Ind. J. Pharm. Sciences, 68 (1), 13 (2006). Bethany Halford, Chem. Eng. News 84, 13, p.47 Oct (2006)

23 Medical Summary!! Seem to have great potential in medicine!! Exposed to light or not!! Anti-oxidants in general!! Generate radicals via triplet state on light exposure!! Water soluble or not!! Tissue take-up!! Absorption in lipid bi-layers (can cause cell death, e.g. anti-bacterial)!! Clustering behaviour!! Medical use toxic or not?!! Need very specific testing for the exposure conditions.!

24 Filled Fullerenes! Filled fullerenes for MRI (magnetic resonance imaging) Sc 3 C 80 Robert Lenk, Luna nanoworks Also with scandium, yttrium, and lanthanum more effective contrast agent in MRI currently inject Gd Gd toxic, so wrapped in an organic compound toxicity not completely removed, limits dose 40x better contrast than agents currently on the market Stay in body ~1 hour Yet to go through drug trials Similar idea for X-ray contrast agents (Ho 3+ ) and Radiopharmaceuticals (Ho 3+ and Tm 2+ ) Filled fullerenes for quantum computing C 60 The electron spin in 14 N@C60 can be used as a resource for the nuclear spin qubit.

25 Fullerene based solids : Fullerites! Polymerised fullerenes give fullerites, new ultra-hard materials. Ultrahard fullerite has hardness of 310 GPa, greater than diamond (167GPa) - Fullerite tip scratch on the (111) diamond surface plastic deformation of the diamond Bulk modulus K ~ GPa measured, cf GPa for diamond Synthesis difficult HPHT (15GPa, K) Berber et al, PRB70, (2004)

26 nano 6 Carbon Nanotubes Fullerenes Graphene

27 Graphene! DEFINITION: One atom thick hexagonal layer made exclusively of carbon atoms. Graphene was first produced in 2004 and Andre Geim and Konstantin Novoselov were awarded the Nobel prize in Physics for their experiments in Graphene is the ultimate twodimensional material, it has open a new venues in physics.

28 Graphene The suffix -ene = related to fused polycyclic aromatic hydrocarbons. Graphene may be considered as the final member of this series, the largest member with quasi-infinite size. Benzene Naphthalene Anthracene Phenanthrene Graphene Graphene is an aromatic system (resonant bonds) «Ideal» graphene is not very chemically reactive F-Graphene* B.E.=0.81 ev/f DFT/LDA, 4x4x1 unitcell F2-Graphene * Single Au atom on Graphene ** B.E. = 1.10 ev/f B.E =0.66 ev *C.Bittencourt, G.Van Lier, X.Ke, I.Suarez-Martinez, A.Felten, et al ChemPhysChem 2009, 10, ** I. Suarez-Martinez, C Bittencourt, X Ke, A. Felten et al. Carbon 47 (2009)

29 Two-dimensional solid! Infinite layer of graphene: supercell 128C (8x8x1)

30 Two-dimensional solid! Infinite layer of graphene: supercell 128C (8x8x1)

31 Graphene K A. K. Geim, A. H. MacDonald, Physics Today 60 (8), 35 (2007)

32 Andrea Ferrari (2011)

33 Micromechanical Cleavage (scotch tape)! Andre Geim (2011)

34 Liquid Phase Exfoliation : Graphene Oxide (GO)!! Acid treat (e.g. HNO 3 ) graphite and sonicate!! Graphene layers become oxygen functionalised and peel off the graphite!! Good cheap way to produce graphene solutions!! Graphene Oxide (GO) is NOT graphene (e.g. non-conductive, water soluble))!! Good for composites and chemical functionalisation! Rod Ruoff (2011)

35 Graphene Oxide (GO) /Reduced Graphene Oxide (RGO)! Hydrazine Treatment RGO is NOT graphene! Functionalised graphene produced in tonne quantities Vorbeck.com M. Segal, Nature Nanotechnology 4, (2009) doi: /nnano

36 Graphene DEFINITION: One atom thick hexagonal layer made exclusively of carbon atoms. PROPERTIES! Thinnest imagineable material! Largest surface area (~2700m 2 / g)! Strongest material (Modulus ~1100 GPa, Fracture strength ~130GPa)! Low density ~2g/cm 3 (light)! Stiffest material (stiffer than diamond)! Most stretchable (up to 20% elasticity) K A. K. Geim, A. H. MacDonald, Physics Today 60 (8), 35 (2007)! Record thermal conductivity (beats diamond) ~3000W/m-K in plane, ~2 W/m-K out of plane! Highest current density at room T (10 6 x Cu)! Gas impermeable (blocks all gases when defect free)! Highest intrinsic mobility (100x Si)! Lightest charge carriers (zero rest mass!)! Longest mean free path at room T (micron range)

37 Potential applications! Watches / calendars Touch screens, Microelectronics Thin flexible light panel Composite materials Mobile phones Tablet computers Electronic payment Solar cells Royal Swedish Academy of Sciences

38 SungKyunKwan University / Samsung! S. Bae et al, Nature Nanotechnology 5, (2010)

39 Replacement for ITO?! Transparent conducting electrode Cheaper, more available source Stronger, flexible S. Bae et al, Nature Nanotechnology 5, (2010)

40 Gas Barrier!

41 Graphene related forms! Carbon Nanowalls: vertically oriented graphenes on a substrate Multiple stacked graphenes Similar growth method as for multi-walled carbon nanotube (MWCNT) growth. The walls are typically less than 10 nm and typically a micron long. This material is expected to be of interest for field emission.

42 Graphene related forms! Carbon Nanoribbons: Armchair, zigzag and (chiral) SYNTHESIS OF NANORIBBONS!! Lithography of graphenes!! Bottom-up synthesis!! Klaus Müllen and colleagues!! Possibility also for 3D structures!! Plasma opening nanotubes!

43 «Unzipping» carbon nanotubes! Materials science: Nanotubes unzipped M.Terrones, Nature 458, 845 (2009) doi: /458845a

44 C. Soldano, A. Mahmood, E. Dujardin

45 Vol July 2010 doi: /nature09211

46 Graphene nanoribbons!!"!" Ph. Wagner et al, PRB, submitted (2011)

47 Graphene nanoribbons! M. Baldoni, A. Sgamellotti, F. Mercuri, Chem. Phys. Lett. (2008), 464, 202

48 nano 6 Carbon Nanotubes Fullerenes Graphene

49 Carbon Nanotubes! DEFINITION: Tubular hollow-core sp2 bonded carbon nanostructure with no axially oriented edges, where the tube walls are approximately parallel to the tube axis at all times. Iijima first identified carbon nanotubes as a by-product ofa fullerene experiment. Transmission Electron microscopy image of a single-wall carbon nanotube They are often defined as wrapped graphene but they are not made that way! Sumio Iijima, Japan, 1991

50 Single Walled carbon nanotubes! They are often defined as wrapped graphene but they are not made that way! Hoewer, this definition helps to undestand their nomenclature CHIRAL VECTOR: Hamada indices (n,m) define the diameter and electrical properties of single-wall nanotubes!"#$%!"#$%"#$%#&%"!"#&%')*$'&+"!"&#$%!"#"%"&'()*&$'"

51 Electronic properties of SWNT When n-m is a multiple of 3 the tube is metallic Modelling capping not always easy! METALLIC Semiconducting or METALLIC

52

53 Nanotube Synthesis!! Arc-electric : two graphite rods, sharpened, electric spark between tips!! Metal catalyst for single-walled nanotube!! Laser ablation of a graphite powder target!! Chemical Vapor Deposition :from an organic molecule!

54 Nanotube Forests!

55 Bundling! SWNT are generally in bundles - size of bundles : typically 10 to 200 nanotubes - orthorhombic-like structure - inter-tube distance d vdw ~ 3.15 Å Bundle of SWNT (TEM - ONERA) Bundle of SWNT (GDPC - Montpellier) 2 Chiral SWNT (STM image - U. Illinois, Urbana, USA)

56 c) d),"-(","-("

57 «Dogbone» tubes! '()*%+),-%./0%*-12(3-45%

58 Unique properties for many potential applications - high aspect ratio length/diameter, small diameters, metallic NTC => field emission, composites with conductive behavior - very high current density (the higher! 10 9 A/cm!) => vias (interconnexion between 2 levels of transistor in a chip) field emission - balistic electronic transport => Field-effect-transistor (FET) - elastic (Young) modulus (the higher! 1 Tpa : Pa) => composites with mechanical behavior - thermal conductivity (the higher! 4000 W/m.K) => composites, components - very high surface/volume ratio, broad potential range of electrodes => sensors, supercapacity, biologic applications

59 (b) Field-emission properties and applications

60 Benefits from CNT for field-emission - High aspect ratio => smaller voltages to emit electrons - high current values (0,1-0,2 ma) => more light - stable light emission Bonard et al., Appl. Phys. A 69, 245, 1999

61 Fibres made with lots of nanotubes: ultra-strong, ultra-resistant

62 How to purify water?! VIDEO

63 nano 6 Carbon Nanotubes Fullerenes COMING UP MORE EXOTIC FORMS Graphene