Nano Materials to Devices - K.R Koswatta

Atomic hydrogen adsorption behavior of boron nitride nanomaterial

Outline

1. Introduction

2. Sample preparation & Deuteration.

3. TOF

4. NEXAFS- Experiment & Calculation.

5. XPS-Experiment & Calculation.

6. PSID.

7. Why H/D prefers to adsorb on B site ?

Kaveenga Rasika Koswattage (PhD) Senior Lecture

Faculty of Applied Science,

Sabaragamuwa University

1

Transportation Fuel cell power technology Renewable

Sustainable

Light-duty vehicles

Light storage system

Introduction

CNT BNNT

US DOE on board hydrogen system has proposed to achieve 5 wt % hydrogen storage by

Introduction

C-H

Hydrogenation degree

= 0.370.05

A. Nikitin et al., Surf. Sci. 602,

2575 (2008).

C 1s XPS

Bending of C–H

bonds

H adsorbed on

neighbor carbon

Hydrogen adsorption on BN is site selective

H

B N

Wu et al., J. Chem. Phys.

121, 8481 (2003).

V.A Margulis et al.,

springer , 275 (2007).

Graphite

Hydrogenation on BNNT > CNT Ex: R. Ma et al., J. Am. Chem.

Soc. 124 , 7672 (2002).

H atom prefers

to adsorb on the

top site of the B

H atom prefers

to adsorb on the

top site of the N

Two hydrogen atoms adsorbed on-top sites

of adjacent B and N atoms Z. Zhou et al., J. Phys. Chem. B

110, 13363 (2002).

Hydrogenation was examined using thin film of h-BN 3

Ni(111)

substrate

·lattice constant

·atomic distance

lattice

matching

h-BN 2.51 Å

Ni(111) 2.49Å -0.4 %

Pd(111) 2.76Å 10 %

Pt(111) 2.89Å 15.2 %

Borazine

(B3N3H6)

N N B

B B

H

H H

H

H

H N

Ni(111) ~800 ℃

Precursor gas Nagashima et al., Phys.

Rev. B 51, 4606 (1995).

BN film on Ni(111) substrate

Chemical Vapor Deposition

Thin film of h-BN on a Ni(111) substrate was selected for the investigation

W. Auwarter et al., Surf. Sci.,

429, 229 (1999). h-BN on a Ni(111)

Well ordered Highly commensurate Perfect lattice match

C 1s VB

0 100 200 300 400 500

0

500

1000

1500

2000

Inte

nsi

ty /

cps

Binding Energy / eV

Ni 3s

Ni 3p

B 1s

N KLL Auger

N 1s

B KLL Auger

hν = 695 eV

Fig. XPS after formation of BN film on Ni(111)

Thickness of the BN film was estimated to be 6.6 Å 4

5

Photon Factory- High Energy Accelerator Research Organization (KEK), Japan

Experiment using Synchrotron Radiation

Beam line 11-A

F

BK EhE

X-ray Photoelectron spectroscopy (XPS)

(a). XPS spectra of clean HOPG

(b). H treated HOPG with H saturated coverage

A. Nikitin et al., Surf. Sci. 602, 2575 (2008).

(a)clean HOPG

(b).H treated

HOPG

6

180 188 196 204 212 220 228

Vacuum

*

Core level

σ*

Unoccupied

levels

Excitation

Energy

Photon Energy / eV

Ab

sorp

tion I

nte

nsi

ty

Synchrotron

Radiation

*

σ*

Photon Energy (eV)

Ab

sorp

tion

in

ten

sity

(ar

b. un

its.

)

NEXAFS

σ*

*

(a) (b)

Continuum States

Eπ*

Eσ*

IP

IP

FL

ValenceBand σ*

(b). A typical B – Kedge NEXAFS spectrum of

bulk h-BN which shows two features, π* and σ*.

(a). Schematic representation of the processes involved in NEXAFS for unsaturated

compounds with double or triple bonds.

Near-edge X-ray absorption fine structure (NEXAFS)

I. Shimoyama et al., J. Elec. Spec. Relat. Phenom.

137, 573 (2004).

7

Grazing incidence ： Enhancement of 1s *

Normal incidence ： Enhancement of 1s σ *

E

G razing

incidence

N ormal

incidence

N

G

* s *

O

O s

E

π orbital

σ orbital

E

sp2

θ=20º

θ=90º

Polarization dependence -NEXAFS

C K-edge NEXAFS spectra of single-crystal

graphite at various incident angles (θ )

R.A. Rosenberg et al., Phys.

Rev. B 33, 4034 (1986).

8

② NEXAFS

Au mesh

試 I(h)

①XPS

I0 (h)

Synchrotron

radiation ring

A

A

hν=700 eV

Hot filament system

X-ray gun

QMS

Analyzer

Ion gun

Hot

filament

system

Ultra high vacuum chamber

Base pressure of the UHV chamber was ~8×10-8 Pa

Experimental

I(h)

I0 (h)

All the experiments were

performed at the BL-11A beam

line of the Photon Factory. BN/Ni(111)

07.0 A

10.0 V 9

NEXAFS -Spectral change by atomic deuterium treatment

400 410 420 430 440In

ten

sity

(arb

. u

nit

)

N K-edge

Photon Energy / eV

Before

After

188 192 196 200 204

Inte

nsi

ty (

arb

. u

nit

)

B K-edge

Photon Energy / eV

π*B

π*A σ* Before

After

Experimental results-NEXAFS

Interaction change between

film and substrate by

deuterium adsorption

1.Formation of B-D bond or

2. Interaction change between film and

substrate by deuterium adsorption or

3.Resultant of these two phenomena. 10

Spectral change between π*A

and σ*showing similar

polarization dependence like

π*A & π*B .

185 190 195 200 205 210

Inte

nsit

y (

arb

. u

ni )

Photon Energy / eV

angle ( ) = 20

angle ( ) = 35

angle ( ) = 55

B

D

Out of plane orientation – B-D bonds are perpendicular to the surface

Out of plane orientation was used for DV-Xα calculation

Spectral change between π*A & σ*

Formation of B-D bond

E SR

Polarization dependence NEXAFS

Before

After

Before

After

Before

After

B K-edge

11

BN film- B27N27H18

Unoccupied

states

Vacuum

π*

σ* 0.5

0.5

One H on B site

One H on N site

Two H on adjacent B&N site

DV-Xα Calculation

Slater’s transition theory

☆Minimal basis set :

•2s & 2p for B&N

•1s for H

▲Model clusters :

optimization :

Win MOPAC / AM1

Model clusters Calculation method

B

N

H

( A molecular orbital calculation method)

12

1. One H attached to B site

DV-Xα Calculation- NEXAFS

B 1s to LUMO

π* σ*

B-Without H

B-With H

13

N-With H

N-Without H

2. One H attached to N site N 1s to LUMO

π* σ*

DV-Xα Calculation- NEXAFS

14

XPS-Spectral change by atomic deuterium treatment

188 190 192 1940

1

2

3

4

Inte

nsi

ty (

arb

. u

nit

)

Binding Energy / eV

Additional component appeared at low BE

Before

After

B 1s

396 398 400 4020

1

2

3

Inte

nsi

ty (

arb

. u

nit

)

Binding Energy / eV

Broadening to high BE

Before

After

N 1s

Experimental results-XPS

15

188 190 192 1940

1

2

3

4

Inte

nsi

ty (

arb

. u

nit

)

Binding Energy / eV

Before

After

B 1s

396 398 400 4020

1

2

3

Inte

nsi

ty (

arb

. u

nit

)

Binding Energy / eV

Before

After

N 1s

XPS calculation

XPS-Spectral change by atomic deuterium treatment

Cluster

Chemical shift ( eV)

Hydrogenated sites Neighboring sites

B 1s N 1s B 1s N 1s

B27N27H18+HB -0.7 N/A N/A -0.4

B27N27H18+HN N/A +2.2 -2.0 N/A

B27N27H18+2HBN -1.6 +2.2 N/A N/A

DV-Xα Calculation- XPS

B-D

16

187 188 189 190 191 192 193 194 195

Binding Energy / eV

Inte

nsit

y (

arb

. u

ni )

BD

A

A* Rtop

Degree of deuteration was estimated to be 29 % considering only B site.

NEXAFS and XPS results imply that atomic deuterium adsorption

occurred on B site more preferentially than on N site

,100 topD

D

RAB

B

Degree of deuteration (%) =

Degree of deuteration

17

Deuterium ion

X-ray

（N excitation）

X-ray

（B excitation）

Why PSID ?

NEXAFS and XPS spectroscopic methods are not considered to

be methods of directly detecting hydrogen from the surface

Photon stimulated ion desorption ( PSID)

PSID can be employed to study hydrogen adsorption sites on a BN film

Time of flight mass spectrometer

18

PSID yield () spectra for D+ ion

Clear increase at the B

K-edge

0

40

80

120

160

184 188 192 196

395 400 405 410

B

Photon Energy / eV

N

D+

des

orp

tio

n y

ield

(

arb

. u

nit

)

Electron excited to

* state

B-D anti bonding

state

does not show clear increase in the N K-edge

N sites adsorbed by deuterium was smaller than B 19

Why H/D prefers to adsorb on B site ??

Explanation is based on the frontier orbital theory

0.00

0.05

0.10

0.15

0.20

0.25

-20 -10 0 10 20

P

DO

S o

f B

Ground state

Energy / eV

B site

H

1st H atom

0.0

0.1

0.2

0.3 N 2s

N 2p

-20 -10 0 10 20

PD

OS

of

N

Energy / eV

N site

π* σ* π* σ* B site- without H N site- without H

Wu et el J. Chem. Phys.,

121 (17), 8481 (2003).

H atom chemisorbs

on the BN

The HOMO of H interacts

with the LUMO of the BN

20

H

2nd H atom

H attached to B –Neighboring B&N

Neighboring B site

Ground state

Neighboring N site

Neighboring N site

Neighboring B site

-20 -10 0 10 200.0

0.1

0.2

0.3

Energy / eV

N 2s

N 2p

N P

DO

S

0.0

0.1

0.2

0.3

B P

DO

S

B 2s

B 2p

Why H/D prefers to adsorb on B site ??

21

2H attached to adjacent B&N Zohu et al : Most stable

configuration

NEXAFS calculation : PDOS of B1s/N1s to LUMO transition

Clear spectral change in π* observed for B and N sites 22

The hydrogenation properties of a h-BN thin film were investigated

as a model material of BN nanomaterials for chemisorption-based

hydrogen adsorption.

The degree of the deuteration was estimated to be 29 % from the

spectral change of the B 1s XPS spectra.

The XPS and NEXAFS spectra of h-BN on Ni(111) were interpreted

using the DV-Xα method, considering the core-hole effect.

The results for the B and N sites implied that deuteration mainly

occurs on B sites. The PSID results support the idea that B sites of BN

are preferentially adsorbed by atomic deuterium

Finally, I concluded that atomic hydrogen is preferentially adsorbed

on B sites in a single hydrogen adsorption mechanism on BN material.

Summary

23

24

Selective adsorption of atomic hydrogen

on a h-BN thin film

Outline

1. Introduction

2. Sample preparation & Deuteration.

3. TOF

4. NEXAFS- Experiment & Calculation.

5. XPS-Experiment & Calculation.

6. PSID.

7. Why H/D prefers to adsorb on B site ?

Kaveenga Rasika Koswattage

the "forever fuel" that we can never run out of

HYDROGEN

It’s abundant, clean, efficient, and can be derived from diverse domestic resources.

Light-duty vehicles

Light storage system

Storing hydrogen in light storage system is required Materials at nano scale

Carbon nanotubes (CNTs) are allotropes of

carbon(同素异形体）(graphite 石墨，diamond钻石， Fullerene）with a cylindrical

nanostructure. Nanotubes have been

constructed with length-to-diameter ratio of

up to 28,000,000:1,which is significantly

larger than any other material.

Discovered in 1991 by the Japanese electron microscopist Sumio Iijima.

Carbon nanotubes

(a) (b)

Crystal structures: (a). Hexagonal boron nitride (h-BN) (b). Graphite.

Boron nitride (BN) nanomaterials

Transportation Fuel cell power technology Renewable

Sustainable

Light-duty vehicles

Light storage system

CNT

US DOE on board hydrogen system has proposed to achieve 5 wt % hydrogen storage by

Introduction

H2 H2

H2 H2 H2 H H

H H H

Quality of the sample problems

Contamination

Defects

Diameter dependence.

Single wall /Multi wall

1996 1998 2000 2002 2004 2006 2008

0.01

0.1

1

10

SW-CNT- Physisorption BNNT- Physisortption .

SW-CNT- Chemisorption

Hyd

rogen

up

tak

e /

wt%

Year

DOE target

Hydrogenation by ,

chemisorption >

physisorption

Nikitin et al. Nano

Letters, 8, 162 (2008).

Physisorption Chemisorption

Reported hydrogen uptakes …..

BNNT One of the

promising

candidates

Volumetric and gravimetric hydrogen density of some selected hydrides.

Hydrogenation by chemisorption > physisorption

A. Zuttel et al, Phil. Trans. R. Soc. A 368, 3329 (2010)

For graphite

Hydrogenation degree at saturation coverage of atomic hydrogen

adsorption and desorption of hydrogen as a function of temperature were

reported.

Formation of C-H bonds at the surface under atomic hydrogen treatment

employing X-ray photoelectron spectroscopy (XPS) was reported.

A. Nikitin et al, Ruffieux et al C-H

Hydrogenation

degree = 0.370.05

Saturation coverage of atomic hydrogen adsorption values estimated by

XPS and other techniques ( TDS) are coincides .

T. Zecho et al , A. Nikitin et al.

C-H

H adsorbed on neighbor carbon

bending of C–H bonds

2. Hydrogen adsorption on BN is site selective

BN nano-materials

This suggestion/coverage for hydrogen adsorption has not been

experimentally verified

1. Hydrogenation on BNNT > CNT Ex: R. Ma et al ,J. Am. Chem.

Soc. 124 (26) ,7672 (2002).

H

B N

Wu et al., J. Chem. Phys.

121, 8481 (2003).

V.A Margulis et al.,

springer , 275 (2007).

H atom prefers

to adsorb on the

top site of the B

H atom prefers

to adsorb on the

top site of the N

Two hydrogen atoms adsorbed on-top sites

of adjacent B and N atoms Z. Zhou et al., J. Phys. Chem. B

110, 13363 (2002).

Hydrogenation was examined using thin film of h-BN

Ni(111)

substrate

·lattice constant

·atomic distance

lattice

matching

h-BN 2.51 Å

Ni(111) 2.49Å -0.4 %

Pd(111) 2.76Å 10 %

Pt(111) 2.89Å 15.2 %

Borazine

(B3N3H6)

N N B

B B

H

H H

H

H

H N

Ni(111) ~800 ℃

Precursor gas

Well ordered

Highly commensurate

Perfect lattice match

BN film on Ni(111) substrate

Chemical Vapor Deposition

Thin film of h-BN on a Ni(111) substrate was selected for the investigation

h-BN on a Ni(111)

pressure of

1×10-4 Pa

W. Auwarter et al., Surf. Sci.,

429, 229 (1999).

Nagashima et al., Phys.

Rev. B 51, 4606 (1995).

F

BK EhE

X-ray Photoelectron spectroscopy (XPS)

XPS spectra of clean HOPG (a) and H treated

HOPG with H saturated coverage (b).

A. Nikitin et al., Surf. Sci. 602, 2575 (2008).

(a)clean HOPG

(b).H treated

HOPG

180 188 196 204 212 220 228

Vacuum

*

Core level

σ*

Unoccupied

levels

Excitation

Energy

Photon Energy / eV

Ab

sorp

tion I

nte

nsi

ty

Synchrotron

Radiation

*

σ*

Photon Energy (eV)

Ab

sorp

tion

in

ten

sity

(ar

b. un

its.

)

NEXAFS

σ*

*

(a) (b)

Continuum States

Eπ*

Eσ*

IP

IP

FL

ValenceBand σ*

(b). A typical B – Kedge NEXAFS spectrum of

bulk h-BN which shows two features, π* and σ*.

(a). Schematic representation of the processes involved in NEXAFS for unsaturated

compounds with double or triple bonds.

Near-edge X-ray absorption fine structure (NEXAFS)

I. Shimoyama et al., J. Elec. Spec. Relat. Phenom.

137, 573 (2004).

Grazing incidence ： Enhancement of 1s *

Normal incidence ： Enhancement of 1s σ *

E

G razing

incidence

N ormal

incidence

N

G

* s *

O

O s

E

π orbital

σ orbital

E

sp2

θ=20º

θ=90º

Polarization dependence -NEXAFS

C K-edge NEXAFS spectra of single-crystal

graphite at various incident angles (θ )

R.A. Rosenberg et al., Phys.

Rev. B 33, 4034 (1986).

X-ray gun

QMS

Analyzer

Ion gun

Hot filament

system

Ultra high vacuum chamber

Base pressure of the UHV chamber was ~8×10-8 Pa

Experimental

All the experiments were performed at the BL-11A beam line of the Photon Factory.

QMS

Ion gun

Hot filament system

XPS-

analyzer

Manipulator

SR

I0 Monitor

(Au mesh)

Experimental chamber set up for the experiment at the BL-11A

Bending magnet beamline

Energy range of 70 eV – 1900 eV

Max. photon flux of 1012 photons/sec

Resolving power 500 - 4000

Experimental

BL- 11A at KEK-PF

Ni(111)

STEP 1. Ar+ sputtering-

{Ni(111) substrate}

STEP 2. Heated Ni(111) substrate to ~800 ℃

STEP 3.

Introducing borazine

Borazine (B3N3H6)

N N B

B B

H

H H

H

H

H N

Sample preparation

Chemical Vapor Deposition

pressure of

1×10-4 Pa

Nagashima et al., Phys. Rev. B 51, 4606 (1995).

Hot filament system

BN/Ni(111)

07.0 A

10.0 V

2 3 4 5 6 7 8

800

1000

1200

1400

1600

1800

2000

T

emper

ature

/ C

Current / A

Degree of dissociation of a hot filament

system as a function of temperature Filament temperature as a function of current

C. Eibl et al, J. Vac. Sci. Technol. A 16, 2979 (1998).

2. NEXAFS

Au mesh

I(h)

1. XPS

I0 (h)

Synchrotron

radiation ring

A

A

hν=700 eV

I(h)

I0 (h)

Spectroscopic measurements…………..

Schematic diagram of the

experimental arrangement

for ion TOF measurements

CFD

MCA

Pre-AMP

TAC 1/312

Divider

RF cavity

( 500 MHz) AMP

STOP

START

3. TOF

Experimental

Thin film of BN on Ni(111)

Ni (111)

BN thin film

IN1s IB1s

INi3s

t

Composition ratio & Thickness

0

500

hv = 192.1 ,

H+

D +

0

D +

H+

Sample annealed

at 200 C Supposed to

be due to

water

hν =

192.1 eV

sN

sB

sB

sN

I

I

hν

hν

N

B

1

1

1s1B

1s1N

)(

)(

][

][

s

s

)/exp(

)/exp(1

)(

)(

BNin 3s Ni

BNin 1s B

Ni

B

Niin 3s Ni

BNin 1s B

3s Ni

1s B

3s Ni

1s B

s

s

t

t

n

n

hν

hν

I

I

XPS spectrum of as-deposited

BN film on Ni(111)

Equations for estimation of Composition ratio & Thickness

Thickness of the BN film was estimated to be 6.6 Å

[B]/[N] was estimated to be 0.98

C 1s

Sample annealed at 200 C

TOF spectrum after deuterium treatment

Supposed to be

due to water

hν = 192.1 eV

After deuterium treatment

K.R. Koswattage et al., J. Chem. Phys., 135, 014706 (2011).

NEXAFS -Spectral change by atomic deuterium treatment

400 410 420 430 440In

ten

sity

(arb

. u

nit

)

N K-edge

Photon Energy / eV

Before

After

188 192 196 200 204

Inte

nsi

ty (

arb

. u

nit

)

B K-edge

Photon Energy / eV

π*B

π*A σ* Before

After

Experimental results-NEXAFS

Interaction change between

film and substrate by

deuterium adsorption

1.Formation of B-D bond or

2. Interaction change between film and

substrate by deuterium adsorption or

3.Resultant of these two phenomena.

K.R. Koswattage et al., J. Chem. Phys., 135, 014706 (2011).

Spectral change between π*A

and σ*showing similar

polarization dependence like

π*A & π*B .

185 190 195 200 205 210

Inte

nsit

y (

arb

. u

ni )

Photon Energy / eV

angle ( ) = 20

angle ( ) = 35

angle ( ) = 55

B

D

out of plane orientation – B-D bonds are perpendicular to the surface

out of plane orientation was used for DV-Xαcalculation

Spectral change between π*A & σ*

Formation of B-D bond

E SR

Polarization dependence NEXAFS

BN film- B27N27H18

Unoccupied

states

Vacuum

π*

σ* 0.5

0.5

One H on B site

One H on N site

Two H on adjacent B&N site

DV-Xα Calculation

Slater’s transition theory

☆Minimal basis set :

•2s & 2p for B&N

•1s for H

▲Model clusters :

optimization :

Win MOPAC / AM1

Model clusters Calculation method

( A molecular orbital calculation method)

B

N

H

1. One H attached to B site

DV-Xα Calculation- NEXAFS

B 1s to LUMO

π* σ*

B-Without H

B-With H

N-With H

N-Without H

2. One H attached to N site N 1s to LUMO

π* σ*

DV-Xα Calculation- NEXAFS

3. One H attached to B site-Neighbouring B and N

Neighbouring B

Neighbouring N

DV-Xα Calculation- NEXAFS

4. One H attached to N site-Neighbouring B and N

Excitation Energy / eV

Excitation Energy / eV

188 192 196 200 204 208

400 404 408 412

Inte

nsi

ty (

arb

. u

nits

) B 2p

B 2s

N 2p

N 2s

Neighbouring B

Neighbouring N

DV-Xα Calculation- NEXAFS

Cluster dependence B

N

H

B48N48H24

B12N12H12

DV-Xα Calculation- NEXAFS

B48N48H24 B12N12H12

XPS-Spectral change by atomic deuterium treatment

188 190 192 1940

1

2

3

4

Inte

nsi

ty (

arb

. u

nit

)

Binding Energy / eV

Additional component appeared at low BE

Before

After

B 1s

396 398 400 4020

1

2

3

Inte

nsi

ty (

arb

. u

nit

)

Binding Energy / eV

Broadening to high BE

Before

After

N 1s

Experimental results-XPS

Cluster

Chemical shift ( eV)

Hydrogenated sites Neighboring sites

B 1s N 1s B 1s N 1s

B27N27H18+HB -0.7 N/A N/A -0.4

B27N27H18+HN N/A +2.2 -2.0 N/A

B27N27H18+2HBN -1.6 +2.2 N/A N/A

DV-Xα Calculation- XPS

188 190 192 1940

1

2

3

4

Inte

nsi

ty (

arb

. u

nit

)

Binding Energy / eV

Before

After

B 1s

396 398 400 4020

1

2

3

Inte

nsi

ty (

arb

. u

nit

)

Binding Energy / eV

Before

After

N 1s

XPS calculation

XPS-Spectral change by atomic deuterium treatment

B-D

NEXAFS and XPS results imply that atomic deuterium

adsorption occurred on B site more preferentially than on N site

187 188 189 190 191 192 193 194 195

Binding Energy / eV

Inte

ns

ity

( a

rb .

un

i )

BD

A

A* Rtop

Degree of deuteration was estimated to be 29 % considering only B site.

,100 topD

D

RAB

B

Degree of deuteration (%) =

Degree of deuteration

Deuterium ion

X-ray

（N excitation）

X-ray

（B excitation）

Why PSID ?

NEXAFS and XPS spectroscopic methods are not considered to

be methods of directly detecting hydrogen from the surface

Photon stimulated ion desorption ( PSID)

PSID can be employed to study hydrogen adsorption sites on a BN film

Time of flight mass spectrometer

Single bunch

SR

PF- Storage

ring

CFD

MCA

Pre-AMP

TAC 1/312

Divider

RF cavity

( 500 MHz)

AMP

STOP

START

TOF-MS measurement system

Schematic diagram of the experimental arrangement for ion TOF measurements

PSID yield () spectra for D+ ion

Clear increase at the B

K-edge

0

40

80

120

160

184 188 192 196

395 400 405 410

B

Photon Energy / eV

N

D+

des

orp

tio

n y

ield

(

arb

. u

nit

)

Electron excited to

* state

B-D anti bonding

state

does not show clear increase in the N K-edge

N sites adsorbed by deuterium was smaller than B

K.R. Koswattage et al., J. Appl. Surf. Sci., 258, 1561 (2011).

Why H/D prefers to adsorb on B site ??

Explanation is based on the frontier orbital theory

0.00

0.05

0.10

0.15

0.20

0.25

-20 -10 0 10 20

P

DO

S o

f B

Ground state

Energy / eV

B site

H

1st H atom

0.0

0.1

0.2

0.3 N 2s

N 2p

-20 -10 0 10 20

PD

OS

of

N

Energy / eV

N site

π* σ* π* σ* B site- without H N site- without H

Wu et el J. Chem. Phys.,

121 (17), 8481 (2003).

H atom chemisorbs

on the BN

The HOMO of H interacts

with the LUMO of the BN

H

2nd H atom

H attached to B –Neighboring B&N

Neighboring B site

Ground state

Neighboring N site

Neighboring N site

Neighboring B site

-20 -10 0 10 200.0

0.1

0.2

0.3

Energy / eV

N 2s

N 2p

N P

DO

S

0.0

0.1

0.2

0.3

B P

DO

S

B 2s

B 2p

Why H/D prefers to adsorb on B site ??

2H attached to adjacent B&N Zohu et al : Most stable

configuration

NEXAFS calculation : PDOS of B1s/N1s to LUMO transition

Clear spectral change in π* observed for B and N sites

The hydrogenation properties of a h-BN thin film were investigated

as a model material of BN nanomaterials for chemisorption-based

hydrogen adsorption.

The degree of the deuteration was estimated to be 29 % from the

spectral change of the B 1s XPS spectra.

The XPS and NEXAFS spectra of h-BN on Ni(111) were interpreted

using the DV-Xα method, considering the core-hole effect.

The results for the B and N sites implied that deuteration mainly

occurs on B sites. The PSID results support the idea that B sites of BN

are preferentially adsorbed by atomic deuterium

Finally, I concluded that atomic hydrogen is preferentially adsorbed

on B sites in a single hydrogen adsorption mechanism on BN material.

Summary

6th International conference of DV-Xα was held in Korea .

Awarded best research in poster and oral section.