Carbon Engineering Nanocarbon Structures

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1 Carbon Engineering Nanocarbon Structures Diamond Fullerenes Carbon nanotubes (CNT) multiwalled (MNT) Diamond Like Carbon (DLC) Graphene Nanospheres

Allotropes of Carbon Crystalline Diamond Graphite Carbon Amorphous Coal Charcoal Lamp Black Coke Gas Carbon Plant Animal Wood Charcoal Sugar Charcoal None Charcoal Blood Charcoal Carbon Compounds and

2 Allotropes of Carbon Crystalline Diamond Graphite Carbon Amorphous Coal Charcoal Lamp Black Coke Gas Carbon Plant Animal Wood Charcoal Sugar Charcoal None Charcoal Blood Charcoal Carbon Compounds and Materials The C atom: Atomic number Atomic mass Ground state electron configuration Ionization potential First excited state GS term - First excited state term s 2 2s 2 2p ev 4.18 ev 3 P 1s 2 2s2p 35 S

easily from first excited state 2s2p 3 Bond energy is about 4 ev per bond Different hybridisation - different bonds Bonding in carbon One of the reasons why

3 Carbon Compounds and Materials Forms what type of bonds? Valence electrons - Forms strong, directional covalent bonds Valence electrons - 2s 2 2p 2 Energy difference between 2s and 2p orbital is about 4 ev Bonds more easily from first excited state 2s2p 3 Bond energy is about 4 ev per bond Different hybridisation - different bonds Bonding in carbon One of the reasons why carbon is so interesting as an element and as an engineering material is that it has three rather different ways in which it can form bonds. The resulting properties vary widely. Shells & Orbitals Carbon has 6 electrons, so we would expect this electronic configuration

Hybridisation sp 3 fullerine Diamond like Carbon CNT sp sp 2

dimensional solid Polymer of sp hybridised C chains Not very

Carbon fibres 2-D solid Macroscopic analog of nanotubes

of hydrocarbons in gas phase in presence of transition metal

4 Hybridisation sp 3 fullerine Diamond like Carbon CNT sp sp 2 graphite carbynes Carbon Compounds and Materials Carbynes 1 dimensional solid Polymer of sp hybridised C chains Not very stable (high T and P) Reported for rapidly quenched carbons Carbon fibres 2-D solid Macroscopic analog of nanotubes Graphite related material Grown from thermal decomposition of hydrocarbons in gas phase in presence of transition metal catalyst particle Layered structure, but not a perfect structure

Carbon Compounds and Materials Diamond 3 dimensional

5C bond angle Solid at room temperature High melting

Graphite Sheets of sp 2 hybridised C atoms 120 bond

orbitals Hexagonal crystal Lattice parameters a = 0.

5 Carbon Compounds and Materials Diamond 3 dimensional solid Covalent network of sp 3 hybridised C atoms 109.5C bond angle Solid at room temperature High melting point Hard Clear Carbon Compounds and Materials Graphite Sheets of sp 2 hybridised C atoms 120 bond angle 2 dimensional solid Sheets weakly bonded by p orbitals Hexagonal crystal Lattice parameters a = nm, c = Density = 2.26 g/cm 3 C-C bond length nm Semi-metal Wide band gap semiconductor Bandgap = 5.47 ev Graphite

Graphene image : Wikipedia Graphene Possible

(non-linear optical property) sensors for gas molecules

6 Graphene image : Wikipedia Graphene Possible applications: spintronics ultrafast photonic devices (non-linear optical property) sensors for gas molecules (surface area, effect on resistance argument) ribbons of graphene as interconnects? ballistic transistors (low on-off ratio and gain though <40) Feb.2010 IBM researchers switch graphene transistor at 100 GHz!!! transparent conducting electrodes/coatings ultra-capacitor electrodes lithium ion cell anodes

Graphene Graphene only one atom thick, optically transparent, chemically inert, and an excellent conductor.

Transparency Elastic Thermal conductivity Impermeable Strongest material found Wonderful candidate for photovoltaics Absorb phonons at

copper) at RT highest intrinsic mobility (100 times more than in silicon) conducts electricity in the limit of no electrons Only absorbs

7 Graphene Graphene only one atom thick, optically transparent, chemically inert, and an excellent conductor. Some facts Strength No band gap Ballistic conduction Best at electricity? Transparency Elastic Thermal conductivity Impermeable Strongest material found Wonderful candidate for photovoltaics Absorb phonons at all frequencies Unimpeded flow of electrons at RT Similar to superconductivity but at RT the highest current density (10^6 that of copper) at RT highest intrinsic mobility (100 times more than in silicon) conducts electricity in the limit of no electrons Only absorbs 2.3% Good for solar cells and touch screens 20% elongation Beats diamond Best conductor known most impermeable material ever discovered Even helium atoms cannot squeeze through great material for building highly sensitive gas detectors

Where does all this lead? Perfect graphenes consist exclusively of hexagonal cells; pentagonal and heptagonal cells constitute defects.

Likewise, insertion of an isolated heptagon causes the sheet to become saddle-shaped.

Single-walled carbon nanotubes may be considered to be graphene cylinders; some have a hemispherical graphene cap (that includes 6

Researchers obtained relatively large graphene sheets (eventually, up to 100 micrometers in size and visible through a magnifying

8 Where does all this lead? Perfect graphenes consist exclusively of hexagonal cells; pentagonal and heptagonal cells constitute defects. If an isolated pentagonal cell is present, then the plane warps into a cone shape; insertion of 12 pentagons would create a fullerene. Likewise, insertion of an isolated heptagon causes the sheet to become saddle-shaped. Controlled addition of pentagons and heptagons would allow a wide variety of complex shapes to be made, for instance carbon NanoBuds. Single-walled carbon nanotubes may be considered to be graphene cylinders; some have a hemispherical graphene cap (that includes 6 pentagons) at each end. Graphene production Graphene sheets in solid form (e.g. density > 1g/cc) is presently one of the most expensive materials on Earth. Researchers obtained relatively large graphene sheets (eventually, up to 100 micrometers in size and visible through a magnifying glass) by mechanical exfoliation (repeated peeling) of 3D graphite crystals. Another method is to heat silicon carbide to high temperatures (1100 C) to reduce it to graphene.

Properties of Graphene The resistivity of the graphene sheet is 10^6 cm, less than the resistivity of silver, the lowest resistivity substance known

These intrinsic properties could lead to the possibility of utilizing Graphene for NEM systems applications such as pressure sensors, and resonators.

the material with a sharp probe made of diamond. Electrons move through graphene with almost no resistance, generating little heat.

Graphene and Applications By oxidizing graphene flakes, and then floating them in water, the graphene flakes form a single sheet and bond very

9 Properties of Graphene The resistivity of the graphene sheet is 10^6 cm, less than the resistivity of silver, the lowest resistivity substance known at room temperature. Graphene is the strongest substance known to man. Its Young's modulus is 0.5 TPa, which differs from bulk graphite. These intrinsic properties could lead to the possibility of utilizing Graphene for NEM systems applications such as pressure sensors, and resonators. Properties of Graphene Engineering professors at Columbia University tested graphene's strength at an atomic level by indenting a perfect sample of the material with a sharp probe made of diamond. Electrons move through graphene with almost no resistance, generating little heat. What's more, graphene is itself a good thermal conductor, allowing heat to dissipate quickly. Graphene and Applications By oxidizing graphene flakes, and then floating them in water, the graphene flakes form a single sheet and bond very powerfully called Graphene oxide paper. Applications: Membranes with controlled permeability Supercapacitors for energy applications. Graphene electronics could be useful for communications and imaging technologies that require ultrafast transistors.

How to grow graphene Two ways CVD Growth from a solid C source Typically from methane C 2 H 2 gas growth automatically stops after a single

across the catalyst The fast and the flexible: Graphene foam batteries charge quickly Capacity on par with existing lithium batteries, but

com/science/2012/10/the-fast-and-the-flexiblegraphene-foam-batteries-charge-quickly/ A graphene FET, or fieldeffect transistor consists of

10 How to grow graphene Two ways CVD Growth from a solid C source Typically from methane C 2 H 2 gas growth automatically stops after a single layer of graphene has formed at low P depositing a source of carbon on a metal catalyst substrate using an 800 furnace to grow the graphene across the catalyst The fast and the flexible: Graphene foam batteries charge quickly Capacity on par with existing lithium batteries, but charges in 15 minutes. A graphene FET, or fieldeffect transistor consists of a single ribbon of graphene with one side laid down on a positive electrode, the other laid down on a negative one. A third electrode, or gate, can then modulate the flow of electrons through the ribbon, turning the device into a switch

GRAPHENE GOODNESS might include: a flexible video display incorporated into a shower curtain, camouflage clothing, and a virtual-reality theatre in the round.

This discovery may lead to smaller yet faster computers in the future. Image Credit: Y.

11 GRAPHENE GOODNESS might include: a flexible video display incorporated into a shower curtain, camouflage clothing, and a virtual-reality theatre in the round. Illustration: James Provost Defects? An artist's conception of a row of intentional molecular defects in a sheet of graphene. The defects effectively create a metal wire in the sheet. This discovery may lead to smaller yet faster computers in the future. Image Credit: Y. Lin, USF Synthetic Diamonds cannot reach actual conditions HPHT technique vs CVD use a catalyst, Ni Co or Fe very high pressure pressure current production, 5 to 10 GPa, usually < 1 carat (200 mg) brown due to nitrogen contamination can be removed using eg Al but growth is slower 6 weeks to grow a 25 carat diamond (5 g)

diamond-like coatings decompose a gas, eg CH 4 on a substrate secret projects in USA and Soviet Union in 1950s first

onwards 27 KPa, 500-800 C decompose feedgas methane + hydrogen stream energise with microwave, laser, electric arc,

Fullerenes somewhat accidental discovery, found in soot!

12 diamond-like coatings decompose a gas, eg CH 4 on a substrate secret projects in USA and Soviet Union in 1950s first reports in 1960 s (on diamond substrates) success on Si and other substrates 1970s explosion of interest in 1980s and onwards 27 KPa, C decompose feedgas methane + hydrogen stream energise with microwave, laser, electric arc, electron beam etc hydrogen etches away any non-diamond carbon not much industrial impact, mostly people in universities! Fullerenes somewhat accidental discovery, found in soot! buckminsterfullerene C60, made in 1985 by Robert Curl, Harold Kroto and Richard Smalley buckyballs any molecule composed entirely of carbon, in form of hollow sphere, ellipsoid or tube image : Wikipedia

Buckyballs Buckminsterfullerene, is composed entirely of carbon atoms.

A total of 60 carbon atoms are present forming a sphere consisting of five-carbon and six-carbon atom

As well as C 60, other sized balls have been created.

C 60 is pink and C 70 is red in solution. What are fullerenes?

13 Buckyballs Buckminsterfullerene, is composed entirely of carbon atoms. Each carbon atom on the cage surface is bonded to three carbon neighbors therefore is sp 2 hybridized. A total of 60 carbon atoms are present forming a sphere consisting of five-carbon and six-carbon atom rings arranged in the same pattern as a modern soccer ball. It is just less than a nanometer in size. As well as C 60, other sized balls have been created. Unlike other forms of carbon, fullerenes may be soluble, as shown in the photograph below. C 60 is pink and C 70 is red in solution. What are fullerenes? 38 Other relatively common clusters are C 70, C 72, C 74, C 76, C 80, C 82 and C 84 (plenty of others, higher or lower than C 60, exist too but less abundant in the experimentally produced mixture fullerene soot). What are fullerenes? (continued ) 39 C 60 C 70

$+ - extract in toluene filter to remove impurities HPLC to purify fractions e - He image :$ Wikipedia Fullerenes applications?

nanotubes) anti-oxidants, radical scavengers, L Oreal has many patents!

14 Fullerenes how are they made? + - extract in toluene filter to remove impurities HPLC to purify fractions e - He image : Wikipedia Fullerenes applications? Michalitsch 2008 initial hype has died down 2% of all nanotech patent (vs 10% for carbon nanotubes) anti-oxidants, radical scavengers, L Oreal has many patents! but most patents point to use as ingredient on organic electronic devices e.g. photovoltaics, photodiodes absorb visible and UV light strongly drug delivery thermally stable lubricants fuel cell electrodes printable conductive inks electrically conducting polymers Fullerene Properties Symmetric shape lubricant Large surface area catalyst High temperature (~500 o C) High pressure Hollow caging particles Ferromagnet? - polymerized C 60 - up to 220 o C

Uses They have many chemical synthetic and pharmaceutical applications. Fascinating electrical and magnetic behaviour including superconductivity and ferromagnetismc 60 is an optical limiter.

15 Uses They have many chemical synthetic and pharmaceutical applications. Fascinating electrical and magnetic behaviour including superconductivity and ferromagnetismc 60 is an optical limiter. When light is shone on it, a solution of fullerene-60 turns darker instantly and the more intense the light, the darker it gets, so the intensity of transmitted light is limited to a maximum value. design of safety goggles in intense light situations e.g. people working with laser beams. Fullerenes may used in certain medical applications - nanomedicine The idea is to use the very small fullerene molecules to easily deliver drugs directly into cells in a highly controlled manner. The extremely small diameter of the nanoparticle fullerenes (which act like a cage to hold the drug) allows them to readily pass through cell membranes. Fullerenes are being developed that have excellent lubricating properties (maybe superior to lubrication oils) from reducing friction in moving metal parts of machines from cog wheels to ball bearings and maybe artificial joints after orthopedic operations on hips and knees! Nanocar Shirai, Y. et al. (2005). Nano Lett. 5: 2330 Don t forget poor old graphite!!!!!!

References Graphene http://en.wikipedia.org/wiki/grapheneaccessed on March, 29 2009 Graphene Confirmed the World s Stronged Known Material http://gizmodo.

nanowerk.com/spotlight/spotid=2340.php accessed on March 29, 2009 TR10: Graphene Transistors http://www.technologyreview.com/read_article.aspx?

16 References Graphene on March, Graphene Confirmed the World s Stronged Known Material accessed on March, Nanotechnology Reserchers go Ballistic Over Graphene accessed on March 29, 2009 TR10: Graphene Transistors alsections&sc=emerging08&id=20242 accessed on March 29, 2009 Graphene: Charged Up accessed on March 29, 2009 Carbon

Carbon 1 of 19 Boardworks Ltd 2016

Carbon 1 of 19 Boardworks Ltd 2016 Carbon 2 of 19 Boardworks Ltd 2016 The carbon atom 3 of 19 Boardworks Ltd 2016 Carbon is a non-metallic element found in group 4 of the periodic table. It has 6 electrons,