Chemical Modification of Graphene

Tobe lab

M1

Kosuke HADA1

• Introduction• Representative previous work about

chemical modification of graphene• My work• Summary

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Outline

Graphene

3

GraphiteGraphene

Graphene

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Graphene

Graphene was isolated by using adhesive tape.

Novoselov and Geim won the Nobel Prize in 2010.

Novoselov, K. S. et al. Science 2004, 306, 666-669.

Graphene

5

Zboril, R. et al. Chem. Rev. 2012, 112, 6156−6214.

Properties of Graphene　・ Strength

　・ Zero band gap

　・ Ultrahigh carrier mobility

New MaterialTouch screensSensorSolar cell

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Chemical Modification ( 化学修飾 ) of Graphene

sp2 carbon : conductivesp3 carbon : non-conductive

Changing of sp2 Carbons to sp3 Carbons by Addition of Organic Molecules

Graphene

or R = moleculeCC CC

RCC

RH

R

• Controlling conductivity of graphene• Functionalizing property of graphene

Representative Previous Work onChemical Modification of Graphene

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Covalent chemistry for graphene electronics

Niyogi, S.; Bekyarova, E.; Hong, J.; Khizroev, S.; Berger, C.; Heer, W.; Haddon, R. C. J. Phys. Chem. Lett. 2011, 2, 2487–2498.

Nitrophenyl Radical

Representative Previous Work onChemical Modification of Graphene

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Nitrophenyl Radical

Epitaxial Graphene (EG)

SicSiC

Sic

Graphene1100 ℃Si

CSi

CSi

CSi

CSi

CSi

CSi

CSi

CSi

CSi

CSi

SiC

SiC

SiC

SiC

SiC

Si

C

SiC

SiC

SiC

SiC

SiC

Si

SiC

SiC

SiC

SiC

SiC

Si

C

SiC

SiC

SiC

SiC

SiC

Si

Si

CSi

CSi

C

Si

CSi

CSi

SiC

SiC

SiC

SiC

SiC

SiC

Si

CC

C

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

C

C

C

CC

CC

CC

CC

CC

C

CC

CC

CC

CC

CC

C

C

C

CC

CC

CC

CC

CC

C

C

CC

CC

C

C

CC

C

CC

CC

CC

CC

CC

CC

CC

C

C

Method of Chemical Modification

Raman Spectrum

Mechanism

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Raman Spectrum

vibration of lattice of graphene

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vibration of defects

Functionalized by NitrophenylEpitaxial Graphene

One or Two Layered Graphene

Scanning Tunneling Microscopy (STM)Mechanism

1111

Tunneling current

Fast Fourier Transform (FFT)

1212

higher-order filteredlower-order filtered

Mechanism

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STM

Nitrophenyl Functionalized Epitaxial Graphene

removing graphene latticehigher-order filteredEpitaxial Graphene

STM

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superimpose( 重ね合わせ )

superimpose( 重ね合わせ )

Epitaxial Graphene

Nitrophenyl Functionalized Epitaxial Graphene

STM

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superimpose( 重ね合わせ )

Moire pattern ( モアレ模様 )

Sic

Graphene

Epitaxial Graphene

STM

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superimpose( 重ね合わせ )

Nitrophenyl Functionalized Epitaxial Graphene

Resistance

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0.4 kΩ at r.t. 3.2 kΩ at r.t.

Epitaxial Graphene Nitrophenyl Functionalized Epitaxial Graphene

• Raman Spector• STM• Resistance

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Summary of the Work

・ Chemical modification change the conductivity of graphene・ Reaction positions and rate weren’t controlled

My purpose is to control reaction positions and rate

= molecules

= substrate

= photoresist

= substrate

light

Top-down approach (photolithography)

Bottom-up approach (molecular self-assembly)

Self-assembly

About 100 nm scale 1~10 nm scale19

Construction of Nano Structure on Surfaces

STM Image of DBA on Graphite

Honeycomb Structure of Dehydrobenzo[12]annulene (DBA) at the Liquid/Graphite Interface

O O

O

OO

O

=

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DBA

Self-Assembly at the Liquid/Solid Interface

Characters of DBA

R

R R

R

DBAOC10: R = OC10H21DBAOC12: R = OC12H25DBAOC14: R = OC24H29DBAOC16: R = OC16H33DBAOC18: R = OC18H37DBAOC20: R = OC20H41

R

R

DBA

=

You can change the size of DBA and holes

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Purpose of My Work

• Chemical stability of diazirine• Precursor of carbene• Photo-reaction under long wavelength

Diazirine

C14H29O OR

OC14H29

ORC14H29O

RO

R = (CH2)10OCF3

NN

DBA 1

C14H29O OR

OC14H29

ORC14H29O

RO

R = (CH2)10OCF3

DBA 1

hv

350 nmDiazirine Carbene

R R'

Y H

R''

R R'

R R'

Y H

R''

• High reactivity• Adding to graphene

Carbene

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Purpose of My Work

=

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Diazirine

Graphene

Self-Assembly

C14H29O OR

OC14H29

ORC14H29O

RO

R = (CH2)10OCF3

NN

DBA 1

Graphene

Purpose of My Work

hv

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OF3C

N N

OF3C

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Purpose of My Work

Graphene and DBA 1 before chemical modification

OF3C

N N

Purpose of My Work

26Graphene after chemical modification

OF3C

Purpose of My Work

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C12H25O OR

OC12H25

ORC12H25O

RO

R = (CH2)8OCF3

NNC14H25O OR

OC14H25

ORC14H25O

RO

R = (CH2)10OCF3

NNC10H21O OR

OC10H21

ORC10H21O

RO

R = (CH2)6OCF3

NN

14 carbons 12 carbons 10 carbons

Graphene and DBA before chemical modification

Purpose of My Work

28Graphene after chemical modification

C12H25O OR

OC12H25

ORC12H25O

RO

R = (CH2)8OCF3

NNC14H25O OR

OC14H25

ORC14H25O

RO

R = (CH2)10OCF3

NNC10H21O OR

OC10H21

ORC10H21O

RO

R = (CH2)6OCF3

NN

28 units 36 units 46 units

14 carbons 12 carbons 10 carbons

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Purpose of My Work

TBSO OMOM

OTBS

OMOMTBSO

MOMO

C14H29O OMOM

OC14H29

OMOMC14H29O

MOMO

CsF, C14H29Br

DMF

10

CBr4

iPrOH

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81% 84%

C14H29O OH

OC14H29

OHC14H29O

HO

K2CO3, 9

acetone

12

19%

OC14H29 OR

OC14H29

OROC14H29

RO

R = (CH2)10OCF3

NN

DBA 1

BrMeO MeOCF3

O

THF

MeOCF3

NOHNH2OH・HCl

EtOH

MeOCF3

NHHN

MeOCF3

NOTs

TsCl, NEt3DMAP

liquid NH3 BBr3

5

6

7 8

Ag2O

Et2O3 4

acetone

CH2Cl2

CH2Cl2 CH2Cl2

BrC10H20Br, K2CO3

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2 79% 89% 94%

93%

84%

67% 46%

N(CH2CH3)2COCF3

n-BuLi

CF3

NN

MeO CF3

NN

HO CF3

NN

BrC10H20O

Protection from Light

STM Image of DBA at the 1,2,4-trichlorobenzene/Graphite Interface

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Cl

Cl

Cl

2.9 × 10-6 mol/LSTM Image of DBA 1

on Graphite

Solvent1,2,4-trichlorobenzene

C14H29O OR

OC14H29

ORC14H29O

RO

R = (CH2)10OCF3

NN

DBA 1

STM Image of DBA at the 1,2,4-trichlorobenzene/Graphene Interface

Cl

Cl

Cl

2.9 × 10-6 mol/L

Solvent1,2,4-trichlorobenzene

C14H29O OR

OC14H29

ORC14H29O

RO

R = (CH2)10OCF3

NN

DBA 1

STM Image of DBA 1 on Graphene

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UV Spector after Photo Irradiation

250 300 350 400 450 5000

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C4H9O OC4H9

OC4H9

OC4H9C4H9O

C4H9O

H3COCF3

NN

250 300 350 400 450 5000

50000

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150000

200000

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300s

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10s

0s

OC14H29 OR

OC14H29

OROC14H29

RO

R = (CH2)10OCF3

NN

DBA 1

photo irradiation of 350~400 nm

stable under photo irradiation photo irradiation generated carbene

photo irradiation generated carbene

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Summary

• Chemical modification changes the properties of graphene.

• I designed DBA 1 and synthesized it.• DBA 1 formed honeycomb structures at

solvent/graphite and solvent/graphene interfaces.

• DBA 1 generates carbene by photo irradiation of about 350 nm.