MATTEO PASQUALIDepartment of Chemical & Biomolecular Engineering,
Department of Chemistry,Carbon Nanotechnology Laboratory,
The Smalley Institute for Nanoscale Science & TechnologyRice University, Houston, TX
QUANTUM WIRESFOR GRID APPLICATIONS
Advanced Electricity Infrastructure WorkshopGCEP, Stanford, CA, 1 November2007
OUTLINE
TeamEnergy challenge and power transmissionCarbon NanotubesArmchair Quantum Wire
Expected featuresProgress so far
Production of single-chirality nanotubes
Separation of nanotubesSpinning of nanotube fibers
Perspective
Rick Smalley
WadeAdams
TEAM
Team effortThough process initiated by Rick Smalley & Wade AdamsIdea of the AQW: Rick Smalley et al.
Multidisciplinary, integrated projectChemistry, Physics, Chem. Eng., Materials ScienceJim Tour, MP, Boris Yakobson, Andy Barron, Jun Kono,
Bob Hauge, Howard Schmidt, Wen-Fang Hwang, et al
Hauge
Tour
Schmidt
YakobsonHwang
Barron Kono
Humanity’s Top Ten Problemsfor next 50 years
1. ENERGY2. WATER3. FOOD4. ENVIRONMENT 5. POVERTY6. TERRORISM & WAR7. DISEASE8. EDUCATION9. DEMOCRACY10. POPULATION
2007 6.6 Billion People2050 9-11 Billion People
RICK SMALLEY’S LECTURE QUIZ
05
101520253035404550
Oil
Coal
GasFiss
ionBiom
ass
Hydroe
lectric
Solar, w
ind, g
eothe
rmal
0.5
2003
05
101520253035404550
Oil
Coal
GasFus
ion / F
ission
Biomas
sHyd
roelec
tric
Solar, w
ind, g
eothe
rmal
2050
Smalley’s Terawatt Challenge
14 Terawatts
210 M BOE/day30 -- 60 Terawatts450 – 900 MBOE/day
Energy:The Basis of Prosperity
20st Century = OIL21st Century = ??
THE ENERGY REVOLUTION
Source: International Energy Agency
SOLAR CELL LAND AREA REQUIREMENTS
Nate LewisCal Tech
Total average daily solar flux: 165,000 TW6 Boxes at 3.3 TW each = 20 TWBoxes are in deserts, far from population centers…
Sou
rce:
NR
EL
US RENEWABLE RESOURCES MAP
Biomass potential: negative energy balance?Harvesting of renewables far from population centers
GEO
BIO
SUN
WIND
Source: DOE & Nate Lewis, Caltech
Currently, power is generated close to population centers
US POWER PLANT MAP
Currently, power plants are near population centersReason: limitations on long-distance power transmissionNuclear is a potential alternative: undesirable near cities
GLOBAL ELECTRICAL ENERGY GRID
Idea of a global grid introduced by Buckminster Fuller (~1970)Will be made of Fullerenes?
Mic
hael
Strö
ck Chirality (n,m) identifiesthe species
(n,0) and (0,m): zig-zag(n,n): armchair(n,m): chiral
•Metallic: n = m (bandgap = 0 eV) •Semi-metallic: n – m is multiple of 3 (“mod 3 tubes,” bandgap ~1-10 meV)•Semiconducting: n – m is not a multiple of 3 (bandgap ~0.5 - 1.0 eV; HiPco 0.8-1.4 eV)
Current methods produce mixtures of metallic/semi-metallic (1/3rd) and semiconductors (2/3rd) Length is polydispersePhysical and chemical polydispersity
SWNTs AS A CLASS OF MATERIALS
SWNT PROPERTIESExceptional mechanical strength
Tensile strength > 37 GPa(Steel 2 GPa, PBO 5.7 GPa, Aluminum 0.3 GPa)Young modulus ~ 0.62 – 1.25 TPa(Steel 0.3 TPa, PBO 0.36 TPa, Aluminum 0.07 TPa)
Low density ~ 1.4 g/cm3(Steel ~8 g/cm3, PBO 1.6 g/cm3, Aluminum 2.7 g/cm3)
Electrical resistivity ~ 1 μΩ cm(Copper 1.7 μΩ cm, Silver 1.55 μΩ cm, Al 2.7 μΩ cm)
Thermal conductivity ~ 3000 W / m K(Diamond ~ 2000 W / m K)
The ultimate polymerThe ultimate carbon material
Review by Baughman et al., Science, 297, 787 (2002)
CONDUCTIVITY OF SWNTs
Measurements on individual metallic SWNT on Si wafers with patterned metal contactsSingle tubes can pass 20 uA for hoursEquivalent to roughly a billion amps per square centimeter!Conductivity measured twice that of copperBallistic conduction at low fields with mean free path of 1.4 micronsSimilar results reported by othersDespite chemical contaminants and asymmetric environment
Dekker, Smalley, Nature, 386, 474-477 (1997). McEuen, et al, Phys.Rev.Lett.84, 6082
RESONANT QUANTUM TUNNELING
Conductance in parallel end-to-end contact ~ single SWNTMisalignment reduces conductance (up to ~10 times)
Buldum and Lu, Phys. Rev. B 63, 161403 R (2001).
Cable of all-aligned armchair SWNTsExceptional potential current carrying capacity
Estimated >1 Billion Amps / cm2 (McEuen et al, IEEE Trans.
Nanotech., 1, 78, 2002)Current technology (steel reinforced aluminum) has1000-5000 Amps / cm2
Combination ofHigh electrical conductivity (~ twice copper at RT)High thermal conductivity (~ diamond)High stiffness: Young Modulus ~0.6-1 TPaSteel 0.3 TPa, Aluminum 0.07 TPa
Low density: 1.4 g/cm3
Steel 8 g/cm3, Aluminum 2.7 g/cm3
THE ARMCHAIR QUANTUM WIRE
Review by Baughman et al., Science, 297, 787 (2002)
ARMCHAIR QUANTUM WIRE PROJECTExpected Features1-10x Copper Conductivity6x Less MassStronger Than SteelZero Thermal Expansion30x Power Density vs. Cu/Al
Key Grid BenefitsReduced Power LossLow-to-No Sag Reduced MassHigher Power Density
SWNT Technology BenefitsType & Class SpecificHigher PurityLower CostPolymer Dispersible
EXPECTATIONS: AQW ON THE GRID
Key Benefits• Eliminate Thermal Failures• Reduce Wasted Power• Reduce Urban R.O.W. Costs• Enable Remote Generation
MAKING THE AQW
What needs to be done:Go from single SWNTto macroscopic material
All-armchair SWNTspreferably all same type
Large quantityAlign and transform into fiber
THREE WAYS OF GETTING IT DONE
Route #1:Sort large amount of armchair SWNTsProcess into fibers
Route #2:Sort minute amount of armchair SWNTsCloneProcess into fibers (maybe on the fly)
Route #3:Grow directly SWNTs of single-chirality by tuning catalyst (variant of cloning)
Process into fibers (maybe on the fly)
ARMCHAIR QUANTUM WIRE PROJECT
initialSWNTsupply
HiPcoCoMoCATLaser-oven
Carpets…
sorting&
separations
1 ng
1 g(enriched)
cutting&
cloning100 X
7 pass:100 kg
1%
99%
fiberspinning
modulusstrength
densityelectrical cond.
thermal cond.
property maps
y
x
applicationsprototype
applications
Selective elimination by electrical breakdown –Collins et al., Science 2001
Covalent functionalization – Strano et al., Science 2003Selective adsorption – Chattopadhryay et al., JACS 2003Ion exchange chromatography – Zheng et al., Science 2003Electrophoresis – Heller et al., JACS 2004Density gradient ultracentifugation –
Arnold et al., Nature Nanotech. 2006Dielectrophoresis – Krupke et al., Science 2003
Separation very difficultLow solubilityMinimal physicochemical differences (except DEP)
Some methods appear scalable, but not highly selectiveOther methods have high selectivity, poor scalability Modeling may help scale-up
SOA: SWNT TYPE SEPARATION METHODS
DENSITY GRADIENT ULTRACENTRIFUGATION
Sort by density SWNTs of different diameterhave (slightly) different density
Does not quite sort by typePossible when few SWNTs present(e.g., CoMoCAT)
Arnold et al, Nature Nanotech,1, 60 2006Hersam
SOA: SINGLE-CHIRALITY CATALYTIC GROWTH
Growth of single type from specific catalystCurrent opinion: SWNTs grow out of liquid metal droplets (catalyst)Droplet (particle) size controls SWNT sizeNarrowest distribution: CoMoCAT
Templated substrateSelectivity by diameter
How to go from diameter to type?
HiPco
CoMoCATResasco
SOA: SEEDED GROWTH/CLONING
Amplification of SWNTsDocking: reduce catalyst particle at endof SWNT with minimal etching,leaving activated catalyst in intimatecontact with SWNT
Growth: cause the seed to growin a CVD chamber. LongerSWNT should be identical to originalone (seed)
Smalley, Tour, Barron, et al, Rice U
Smalley et al, JACS 2006
Seed: 200nm long; amplified: 6.7 μm longSeed and amplified SWNT have same diameter (~0.7 nm)Same chirality not yet provenLow yield: few seeds regrow on surfaces; looking for alternatives
SOA: SEEDED GROWTH/CLONING
SOA: SPINNING OF SWNT FIBERSFour main methods
From water-surfactant suspension (Poulin et al, CNRS Bordeaux)General route; SWNT manufacturing unimportantSome surfactant/polymer may remain in fiber
From a carpet/forest (Baughman et al, UT Dallas)Will be great if cloning is done on carpetsWorks for long CNTs (~1 mm OK)Never demonstrated on SWNTs
From gas-phase reactor (Windle et al, Cambridge)Will be great if “magic” catalyst can be foundWill work for long SWNTs (~1 mm OK)
From LC solution (Rice U)General route; SWNT manufacturing unimportantWill work for medium-length SWNTs(~1 μm proven, maybe ~10 μm)
Baughman
Poulin
Windle
SPINNING FIBERS FROM WATER-SURFACTANTPoulin et al, CNRS Bordeaux
Vigolo et al, Science 290, 1331 (2000)
25 μm
hydrophobic(C-12 chain)
SWNT
charged group(sulfate)
SWNT-ACID LIQUID CRYSTAL
Acid protonate the SWNTs: stabilizationA liquid crystal forms at high SWNT
concentrationSimilarities with rodlike polymers (Kevlar)Liquid crystal morphology depends on
type of acid (sulfuric vs. chlorosulfonic)Stable for months; no chemical reactions
7% wt in ClHSO3, cross polars, 0 and 90°
20 μm
DILUTE SEMIDILUTE
ISOTROPICCONCENTRATED
LIQUIDCRYSTALLINE
Ramesh et al, J. Phys. Chem. B, 2004Davis et al, Macromolecules, 2004
600 ppm wt. 6% wt.
FIBERS FROM SWNT/ACID
Highly aligned fibers; diameter ~20-70 μmContinuous process
Ericson et al, Science, 2004
TYPICAL ACID-SPUN SWNT FIBER
Excellent macrostructurePoor mesostructure (bundles), will affect transport
Ø=37±3µm
Ø=50±2µm
ASSESS WAYS OF GETTING IT DONE
Route #1:Separate large amount of SWNTsProcess into fibers
Large scale separation for fiber spinningWe need a miracle (breakthrough)We know a few places where to look
Flow-dielectrophoresisSelective reactions
Fiber spinningWe have two routes: surfactant, acidEach needs scientific engineering
Flow-DEP
Route #2:Separate minute amount of SWNTsCloneProcess into fibers (maybe on the fly)
Small scale separationWe have a route: CoMoCAT
+ density gradient ultracentrifugationCloning
Concept ~ proven (on surfaces, chirality?)We need a miracle (breakthrough)We know where to look
Fiber spinningTwo routes: surfactant, acidMaybe carpet and/or direct
ASSESS WAYS OF GETTING IT DONE
Route #3:Grow directly SWNTs of single-chirality by tuning catalyst (variant of cloning)
Process into fibers (maybe on the fly)Most elegant route
Fundamental understanding of SWNT growth still evolving
Current understanding:liquid phase catalystdiameter selectivity possible
type selectivity unlikelyFiber spinning
Two routes: surfactant, acidMaybe carpet and/or direct
ASSESS WAYS OF GETTING IT DONE
liquid C
gas
SUMMARY ASSESSMENT
Direct single-chirality growthWe need a miracleWe don’t know where to look
CloningSort-of proven (surface, chirality?)We need a miracleWe know where to look
Fiber spinningWe have four routesNeed scientific engineering
NeedBright, enthusiastic peopleFunding
Humanity’s Top Ten Problems for next 50 years
1. ENERGY2. WATER3. FOOD4. ENVIRONMENT 5. POVERTY6. TERRORISM & WAR7. DISEASE8. EDUCATION9. DEMOCRACY10. POPULATION 2003 6.5 Billion People
2050 10-12 Billion People
RICK SMALLEY’S LECTURE QUIZ
POPULATION
POPULATION
For the first time in history, we now live in a small island
Fully connected, interdependent
Nowhere to go (for a long time)
Insular civilizations (Jared Diamond)
Expanded and overtaxed environment until they collapsed
Learned to control harvest rate and limited population
Technology only makes the problem worse
Creates transient “excess” of resources
Albert Bartlett, “The Essential Exponential”
If then kxdtdx
=0 ,)(lim >∀∞=
∞→ktx
t Bartlett
Diamond
POPULATION
Quick mnemonic: at k% growth rate, the doubling timeis Td = 100 ln2/k = 70/kAt 1% population growth rate:
At 2 kW/person, we run out of solar power in 1) 100 years (AD 2100)2) 1,000 years (AD 3000)3) 10,000 years (AD 12000)4) 100,000 years (AD 102,000)5) Ridiculous: we cannot possibly run out of solar power!
POPULATION
Quick mnemonic: at k% growth rate, the doubling timeis Td = 100 ln2/k = 70/kAt 1% population growth rate:
At 2 kW/person, we run out of solar power in 1) 100 years (AD 2100)2) 1,000 years (AD 3000)3) 10,000 years (AD 12000)4) 100,000 years (AD 102,000)5) Ridiculous: we cannot possibly run out of solar power!
At that time, we will have 2 m2/person of space!At 0.5% population growth rate, we run out of solarpower (and space) in AD 4000!
POPULATION
Current estimates predict that population growth will stopin about 70 years
Estimates of population growth are highly inaccurate beyond average life expectancy (currently ~ 65 yr)
Situation is better now than in the 1960s
We need to remain conscious of it
PREDICTED
CONTRIBUTORS
PhD Students: Virginia Davis, Lars Ericson, Hua Fan, Nick Parra-Vasquez, Richard Booker, Yuhuang Wang, Naty Behabtu
UG Students: J. Sulpizio, Valentin Prieto, Jason Longoria, Robby Pinnick, Jon AllisonPostdocs: Pradeep Rai, Haiquing Peng, S. Ramesh, Rajesh Saini, Micah GreenScientists: Carter Kittrell , Wen-Fang Hwang, Howard SchmidtRice Faculty: Boris Yakobson, Ed Billups, Wade Adams, Robert Hauge, Rick SmalleyU. Penn: Jack Fischer, Karen Winey, Wei Zhou, Juray Vavro, Cszaba Guthy
ACKNOWLEDGEMENTSFUNDING
Office of Naval Research / DURINTAir Force Office of Scientific ResearchAir Force Research LabNational Science FoundationNASA Welch FoundationTexas Advanced Technology Program
REFERENCES (email [email protected])Phase Behavior and Rheology:
Davis et al., Macromolecules, 37, p. 154 (2004)Zhou et al., Phys. Rev. B, 72, 045440 (2005)Pasquali et al., US Patent 6,962,092 (2005)Parra-Vasquez et al., Macromolecules, 40, p. 4043 (2007)
Solubility and Protonation:Ramesh et al., J. Phys. Chem B, 108, p. 8794 (2004)Rai et al., J. Am. Chem. Soc., 128, p. 591 (2006)
Fiber Spinning and PropertiesEricson et al., Science, 305, p. 1447 (2004)Wang et al., Chem. Mater., 17, p. 6361 (2005)Smalley et. al., US Patent 7,125,502 (2006)