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Carbon NanotubesJ. A.

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Introduction “nano” sized – in nanometres 10-9

m, or nm Nanotube – rolled up net of

graphine – single sheet of graphite Peter Wiles and myself published

first accounts of finding nanotubes in 1978, first structure analysis 1979 (cf. Ijiima 1991 in Japan)

1978 TEM

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3After air operation After operation in nitrogen

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Carbon Nanotubes Properties, potential uses, methods of manufacture

General references:

Harris, P. J.F. Carbon nanotubes and related structures Cambridge Uni. Press 1999

Tomanek, D. Enbody, R.J.(eds) Science and application of nanotubes. Kluwer Acad. 2000

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Properties of nanotubes Geometry, size, direction of roll Multwall (MWNT) 5-50 nm dia, 10 μm

long single-wall (SWNT) 1-10 nm dia, 1 μm

long Pentagons or heptagons give defects –

caps at ends, and “junctions” Electrical: conduction or non-conduction Armchair – metallic, Zigzag, chiral - semiconductor

Armchair, zigzag, chiral

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Single nanotubes Pull-out and release of MWNT

– Van der Waals force World’s smallest balance

Weighing a 22 fg particleScience 283, 1513(1999)Applying hf voltage got frequency for resonance

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Single nanotubes Atomic force microscope tip –

resiliant and large aspect ratio –can sense deep into surface cavities

nanotubeon AFMcantilever(1999)

resulting image

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Uses of nanotubes? Electron emission Hydrogen adsorption Easy electrolyte contact Polymer strengthening Transistor components Drug or chemical storageLeading to: Computer, TV displays;

hydrogen for fuel cells, electrodes for Li ion battery, car parts

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Electron emission Minature “cathode ray tube” using

battery voltages 10’s of V Displays for computers, lamps

Samsung display 1999 Lamp 2000

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Hydrogen adsorption Hydrogen storage for mobile fuel

cells – need 6.5 %, 62 kg / m3, best near room temp, a few bar

Many nanotube samples give up to 2 %, some up to 6 % and a few 20 % or more; metal loading.

Understanding why – physisorb vs chemisorb – around 90 kJ /mole activation energy

tank

H2

P, T ?

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Battery/fuel cell electrodes

One electrode in a Li ion battery is porous carbon, where Li+ intercalates; a nanotube electrode is sought for ease of ion approach, reducing polarization

Fuel cell electrode for hydrogen oxidation

Canterbury nanotubeson carbon fibres 2002

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Polymer-nanotube composites Stronger than with carbon fibres?

Theory – small defects, so stronger Practice – stronger, but poor dispersion, smooth surface

Electrical conductivity with photo-luminescent polymer 108 times, also more robust because of nano heat fins

Membrane materials Bioimplant materials