Chemical Modification (化学修飾 )of Graphene

Tobe Lab. M1

Kosuke Hada

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Contents

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• Graphene

• Self-assembly of Molecules

• My Work

• Graphene

• Self-assembly of Molecules

• My Work

Graphene

3

Graphene Graphite

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

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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

・ Changing double bonding of graphene to single bonding

double bonding : strong bondingsingle bonding : weak bonding

Carbon having double bonding : conductiveCarbon having no double bonding : non-conductive

We can control strength and conductivity of graphene

・ Adding molecule having useful properties to grapheneR

or R = molecule

H R

We can add useful property to graphene

Graphene Oxide酸化グラフェン R = Cl, NO2, OCH3, Br

1. N2H4 ・ H2O, pH 1080 ゜ C, 24 h

2. , rt, 1 hR N2+ BF4

-

Example of Chemical Modification of Graphene

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Tour, J. M. et al. J. Am. Chem. Soc. 2008, 130, 16201-16206.

←Photographs of supernatant N,N′-dimethylformamide　 (DMF)　 solutions (上澄み ) obtained from dispersions of (a) graphene and (b) R = Br, (c) R = Cl, (d) R = NO2, and (e) R = OCH3 after centrifugation (遠心分離 ) for 15 min at 3200 rpm

Graphene modified can be dispersed (溶ける ) in polar solvent such as N,N′-dimethylformamide (DMF)

Functionalization With Diazirine of Graphene

R R'

N N hv

-N2

R R'R''

R R'

R''

Diazirine

CarbeneAddition

High Reactivity

TEM Image of Functionalized Graphene

Workentin, M. S. et al. Langmuir 2011, 27, 13261–13268.8

Carbene Addition

(付加反応 )

(高反応性 )

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Problem of Chemical Modification of Graphene

Non-regular modification

We can’t precisely control the property

Regular modification is needed to control precisely the property

Contents

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• Graphene

• Self-assembly of Molecules

• My Work

Construction of Nano Structure on Surfaces

= molecules

= substrate

= photoresist

= substrate

light

Top-down approach (photolithography)

Bottom-up approach (molecular self-assembly)

Self-assembly

About 100 nm scale 1~10 nm scale11

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Tunneling current

Mechanism of Scanning Tunneling Microscopy (STM)

STM

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Tip

Sample

electron

Tunneling current

Tip

Sample Small 　 change

d (distance)

Ji (tunneling current)

Large 　 change

Ji = Aexp(-Bd)

Ji : tunneling currentA, B : constantd : distance

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O OH

OHO

O OH

Lackinger, M.; Griessl, S.; Heckl, W. M.; Hietschold, M.;Flynn, G. W.; Langmuir, 2005, 21, 4984.

Example of 2D Molecular Self-assembly

STM Image of 2D Molecular Self-assemblyat Alkanoic Acids/Graphite Interface

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

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

C12H25O OC12H25

OC12H25

OC12H25C12H25O

C12H25O

=

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Van der Waals Forcebetween the Molecules

Van der Waals Forcebetween the Molecules and the Solid

DBA

Self-Assembly at the Liquid/Solid Interface

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

C12H25O OC12H25

OC12H25

OC12H25C12H25O

C12H25O

=

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STM Image of DBA on Single-Layer Graphene on Cu

DBA

Characters of DBA

R

R R

R

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

R

R

DBA

=

• We can change the size of DBA and holes

• Holes catch the another molecules

Sensor18

Contents

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• Graphene

• Self-assembly of Molecules

• My Work

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• Labeling of biomolecules• Adding to graphene

Carbene

Purpose of My Work

=

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Diazirine

Graphene

Self-Assembly

C14H29O OR

OC14H29

ORC14H29O

RO

R = (CH2)10OCF3

NN

DBA 1

Graphene

OF3C

Purpose of My Work

hv

OF3C

N N

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Purpose of My Work

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Regular modification

We can precisely control the property

STM Image of DBA at the Phenyl Octane/Graphite Interface

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7.2 × 10-7 mol/LSTM Image of DBA 1

on Graphite

Solvent : phenyloctane

C14H29O OR

OC14H29

ORC14H29O

RO

R = (CH2)10OCF3

NN

DBA 1

Summary

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• Graphene is considered as a prospective material because of its unique properties.

• Chemical modification is used to control the properties of graphene and functionalize it

• Self-assembly by non-covalent interactions is used to construct the ordered structures at the solid surface.

• A purpose of my work is to establish an unique approach which makes periodic functionalization of graphene possible based on self-assemblies of molecules at the liquid/graphene interface and following the addition to the graphene.