N. Aldea 1, S. Pintea 1, V. Rednic 1, P. Marginean 1, R. Turcu 1, S. Gergely 1, M. Neumann 2, Y. Xie 3, F. Matei 4 1 National Institute for R&D of Isotopic

N. Aldea1, S. Pintea1, V. Rednic1, P. Marginean1, R. Turcu1, S. Gergely1, M. Neumann2, Y. Xie3, F. Matei4

1 National Institute for R&D of Isotopic and Molecular Technologies, Cluj - Napoca, Romania

2 University of Osnabrück, Fachberiech Physik, Osnabruck, Germany

3 Beijing Synchrotron Radiation Facilities of Beijing, National Laboratory, P. R. China

4 University of Agriculture Sciences and Veterinary Medicine, Math. Department, Cluj-Napoca, Romania

LOCAL, GLOBAL AND ELECTRONIC STRUCTURE OF NANOSTRUCTURED

SYSTEMS

National Institute for R&D of Isotopic and Molecular Technologies, Cluj-Napoca, Romania

The 14-th National Conference “Progresses in Cryogenics and Isotopes Separation”, 29-31 October 2008, Calimanesti-Caciulata, Valcea, Romania

Outlook


A. Some physical and chemical properties of nanostructured materials (supported Au and Ni catalysts, Fe3O4 polypyrrole core-shell composites)

B. Theoretical background of EXAFS, XRD and XPS methods

C. Experimental, data analysis, results and discussion

D. Conclusions

A. Physical and chemical properties


Supported metal catalysts (SMC) are special materials used in complete or partial oxidation, reduction or hydrogenation reactions that change the reaction speed without changing the chemical equilibrium.

Fe3O4 nanocomposites based on polypyrrole and magnetites are biocompatible and offer great promise applications in biotechnology.

A1.A1. Why are we interested to determine crystalline and electronic Why are we interested to determine crystalline and electronic nanostructure ?nanostructure ?

A2.A2. Crystallite size (global structure) determination methods: Crystallite size (global structure) determination methods:

Chemisorption of the hydrogenTEMMagnetic measurements method - based on Longevin’s theory

Powder X-ray diffraction - a new package program: XRSIZE

strong correlationCatalytic activity

the global (XRD), local (XAS) and electronic structure (XPS)



P. Marginean and A. Olaru, Appl. Catalysis A: General 140 (1996) 59

Crystallite domain

Adsorbed hydrogen atoms

Grainsize

A3.A3. Grain size

chemosorption of the hydrogen HRTEM micrograph of Au/TiO2

Masatake Haruta, "Catalyst of gold nanoparticles deposited on metal oxides" Cattech 6 (2002) 102



A4.A4. The activity of supported gold catalysts The activity of supported gold catalysts

R. Grisel, Kees-Jan Weststrate, Andrea Gluhoi, B.E. Nieuwenhuys, "Catalysis by Gold Nanoparticles", Gold Bulletin 35/2 (2002) 45

b) CO oxidation 2CO + O2 → 2CO2a) conversion of propene 2C3H6 + 9O2 → 6CO2 + 6H2O

Synergistic and particle size effects for reactions:

c) Temperature needed for 95% CO conversion versus the average gold particle size of Au/Al2O3 calcined at 300 °C (▲), Au/Al2O3 calcined at 600 °C (■ ), Au/Al2O3 calcined at 900 °C

(♦)and Au/MOx/Al2O3 (●) catalysts. The three Au/Al2O3 catalysts have been calcined at 300, 400 and 600 °C in order to change the average Au particle size

B. Theoretical background


B1. Theoretical outline of local structure of the metal particle nanosize Theoretical outline of local structure of the metal particle nanosize based on EXAFS method based on EXAFS method

B 1.1 The EXAFS function χ(k) is defined in terms of the atomic absorption coefficient )(

)()()(

0

0

k

kkx

B 1.2 The theoretical EXAFS signal is defined by the relation

jjjj kkrkAk )](2sin[)()(

Total amplitude function: )2exp()](/2exp[),,()( 22

2 jj

j

jj kkrrkF

kr

NkA

B 1.3 The single shell contribution may be isolated by Fourier transform technique

max

min

)()2exp()()2/1()( 2/1k

k

n dkkWFikrkkr

B 1.4 The inverse Fourier transform of the radial structure function is obtained for any coordination shell with:

.)2exp()()()/1()/2()(2

1

2/1 drikrrkWFkkj

j

R

R

nn

j



B2.B2. Particle size determination from X-ray diffraction method Particle size determination from X-ray diffraction method

By X-ray line diffraction profile (XRLP) analysis one can obtain crystallite size, microstrain and stacking fault probability.

Methods

Diffraction line broadening analysis - Scherrer method;

For non-overlapped lines

Fourier transform or analysis using Generalized Fermi Function (GFF) for X-ray Line Profiles (XRLP) approximation

•N. Aldea, Andreea Gluhoi, P. Marginean, C. Cosma, Xie Yaning, Extended X-ray absorption fine structure and X-ray diffraction studies on supported nickel catalysts, Spectrochimica Acta B 55, 997 (2000).

• N. Aldea, Andreea Gluhoi, P. Marginean, C. Cosma, Xie Yaning, Hu Tiandou, Whongua Wu and Baozhong Dong, Investigation of supported nickel catalysts by X-ray absorbtion spectrometry and X-ray diffraction using synchrotron radiation, Spectrochimica Acta B 57, 1453 (2002).

•N. Aldea, B. Barz, S. Pintea, F. Matei,Theoretical approach regarding nanometrology of the metal nanoclusters used in heterogeneous catalysis by powderX-ray diffraction method, J. Optoelectron. Adv. Mat 9(10) (2007) 3293.



B3.B3. Theoretical outline of metal particle nanosize based on single x- Theoretical outline of metal particle nanosize based on single x-ray line profile analysisray line profile analysis

Fourier transform method LFLGLH

h(s) – experimental spectrum

g(s) - instrumental function

f(s) - true sample spectrumFredholm integral equation of the first kindIll-posed problem.

dssfssgsh

Convolution equation:

F s - depends on particle size and

stacking faults probability

F ε - depends on microstrainsTwo simultaneous events.

hklD

L

s effeLF

2

220

222

a

Lhhkl

L

eLF

F(L)=Fs(L)F(L)

B3.1 General aspects based on convolution equation:

B3.2 General relation of the true sample function

,sin

2

2Imcos

2

2Re

4

2exp

22

sis

erfcsis

erfcs

0sinsin

2seffD

γ1

erfc(x)=1-erf(x).

dLeesf isLLL 22

2

20

222

a

hL

LLeLF 2

C. Experimental, data analysis, results and discussions


C1. C1. Investigated systems. Investigated systems. Preparation methods Preparation methods

Supported gold catalysts were prepared by homogeneous deposition-precipitation with urea on support of MOx/Al2O3 (M: Cu, Ce, Mg, Li in different combinations).

The gold precursor was HAuCl4·3H2O, Aldrich, 99.999% purity. The theoretical gold content for the catalysts was 5 wt %.The catalysts were calcined at 3000 C before the measurements

C1.1 Supported gold catalysts

0 - Au foil0 - Au foil

1 - Au/LaO1 - Au/LaOxx/Al/Al22OO33

2 - Au/ZnO/MgO/Al2 - Au/ZnO/MgO/Al22OO33

3 - Au/CuO/Al3 - Au/CuO/Al22OO33

4 - Au/CeO4 - Au/CeOxx/Al/Al22OO33

5 - Au/ZnO/Al5 - Au/ZnO/Al22OO33

6 - Au/TiO6 - Au/TiO22

7 - Au/MnO7 - Au/MnOxx/Al/Al22OO33

8 - Au/Al8 - Au/Al22OO33

9 - Au/CeO9 - Au/CeOxx/ ZrO/ ZrOxx/ Al/ Al22OO33

10 - Au/Li10 - Au/Li22O/CeOO/CeOxx/Al/Al22OO33

11 - Au/Rb11 - Au/Rb22O/CeOO/CeOxx/Al/Al22OO33



C1.2 Supported nickel catalysts

The Ni/Cr2O3 and Ni/Al2O3 catalysts were prepared by coprecipitation of the mixture of nickel nitrate and chromium nitrate, respectively, aluminum nitrate with a solution of sodium carbonate/hydroxide.

After precipitation we obtained: NiCO3.2Ni(OH)2.4H2O, Al hydroxide and Cr hydroxide, respectively

In order to eliminate the sodium ions the precipitate was thoroughly washed with double distilled

water. Then the precipitate was dried at 105°C in stove and calcined in nitrogen flow at 340°C and

reduced in flowing hydrogen.

The thermal treatments of the catalysts have been done in hydrogen flow at different temperatures

for 3 hours. Ni/Cr2O3Ni/Al2O3

Ni85Cr15 at %Termal treatement at: 1 - 3500C2 - 4200C3 - 6500C4 - 8500C5 - 9500C

Ni70Cr30 at %Termal treatement at: 6 - 3500C 7 - 6500C 8 - 7500C 9 - 9000C10- 9500C

Ni85Al15 at %Termal treatement at: 11 - 3500C12 - 5500C13 - 7500C14 - 8500C15 - 10500C

Ni70Al30 at %Termal treatement at: 16 - 9500CNi60Al40 at %Termal treatement at: 17 - 10500C


C1.3 Fe3O4 polypyrrole core-shell composites


Ferrofluid SampleMF/Py(v/v)

Polymerizationtime (h)

Fe3O4 : AL+DBS F10 20 6

Fe3O4 : AM+DBS F12 20 20

Fe3O4 : AL+DBS F14* 2 10

o o

o

o o

o

N

N N

N

N

N

N

N

N

o

o

o

o

o

o

o o

o

o

o

o

H

H

H

H

H

H

H

H

H

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o o

o

o o

o

N

N N

N

N

N

N

N

N

o

o

o

o

o

o

o o

o

o

o

o

H

H

H

H

H

H

H

H

H

o o

o

o o

o

N

N N

N

N

N

N

N

N

o

o

o

o

o

o

o o

o

o

o

o

H

H

H

H

H

H

H

H

H

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o



C2.1C2.1 XAS set up on synchrotron radiation for transmission measurementsXAS set up on synchrotron radiation for transmission measurements

drivers

Steppedmotors

encoder

counter

interface

computer

slitIC0

ion chamber

IC1

t

slitslit

monochromater

sample

I0 I

dataacquisition

SRBEAMLINE

GPIB busI=I0e-t

Block diagram of the monochromator control and XAS data acquisition

Bkhkl EEEhEc

d ,,,sin2

C2.C2. XAS measurements XAS measurements



XAS spectroscopy LIII gold edge, fluorescence technique, X-ray energy of incident flux between 11582 - 12806 eV

BSRF - Beijing Synchrotron Radiation Facilities 4W1B beamlines, 30-50 mA, 2.2 GeV, room temperature, ΔE=1-2 eV at E=10 KeV

0 - Au foil1 - Au/LaOx/Al2O3

2 - Au/ZnO/MgO/Al2O3

3 - Au/CuO/Al2O3

4 - Au/CeOx/Al2O3

5 - Au/ZnO/Al2O3

6 - Au/TiO2

7 - Au/MnOx/Al2O3

8 - Au/Al2O3

9 - Au/CeOx/ ZrOx/ Al2O3

10 - Au/Li2O/CeOx/Al2O3

11 - Au/Rb2O/CeOx/Al2O3

── Au(OH)30 200 400 600 800 1000

5

1

0

2

4

3

EX

AF

S F

unct

ions

Energy [ev]0 100 200 300 400 500 600 700 800 900

11

10

9

8

6

7

EX

FA

S F

unct

ions

Energy [eV]

EXAFS signalsEXAFS signals

C2.2.1C2.2.1 SupportedSupported Gold catalystsGold catalystsC2.2C2.2 Results and discussionsResults and discussions



4 6 8 10 12 14-0.0020

-0.0015

-0.0010

-0.0005

0.0000

0.0005

0.0010

0.0015

0.0020(11) Experimental

Calculated

Y A

xis

Titl

e

Wave vector [1/A]

N1 = 12 atoms, R1 = 0.287 nm

N2 = 6 atoms, R2 = 0.407 nm

N3 = 24 atoms, R3 = 0.498 nm

N4 = 12 atoms, R4 = 0.575 nm

The local structural parameters of the investigated samples for the first coordination

shell

Sample Number of atoms

Shell radius [nm]

Au Foil 12 0.287

Au/LaOx/Al2O3 2.82 0.282

Au/CuO/Al2O3 4.61 0.287

Au/ZnO/Al2O3 5.69 0.284

Au/MnOx/Al2O3 2.90 0.284

Au/CeOx/ZrOx/Al2O3 3.44 0.287

Au/Li2O/CeOx/Al2O3 2.93 0.280

Au/Rb2O/CeOx/Al2O3 2.20 0.284

Standard sample:

Numerical resultsNumerical results



•N. Aldea, C. Tiusan, A. Chezan, "Full multiple scattering approximation to K-XANES of supported metal catalysts", Physica B, 208 & 209 (1995) 691.

•K edge for Ni, Cu, Fe;•K edge for Cl (NaCl), F (NaF), K (KCl), K (KF), Ti (TiO), Ti (TiC).

Z = 79, Au:

Discrete transitions

6s

LIII 2p3/2 → 6d3/2

6d5/2

2/32/3

2/52/3

2/3

2/3

62

62

62

2

)(

dp

dp

sp

continuump

stransitionE

XANES AnalysisXANES Analysis



ℒ , ℒ(E)dE = 1, FWHM = Γ, -life time

22

22

)(

EE

E

AB

~1

-2-1

01

23

45

67

89

1011

12 -20-10

010

2030

4050

6070

8090

100

XANES signalsXANES signals

FE

FEEdE

EE

E

2

arctan1

2

1

22

)(0

02

020

0

Transitions probabilityTransitions probability



0

0.2

0.4

0.6

0.8

1

1.2

-20 -10 0 10 20 30 40 50 60 70 80

Norm

alized a

bsorb

ance

E-E0 [eV]

miu(E-E0)-calculatedmiu(E-E0)-experimental

2p3/2 - continuum2p3/2 - 6s

2p3/2 - 6d3/22p3/2 - 6d5/2

2/32/3

2/52/3

2/3

2/3

62

62

62

2

)(

dp

dp

sp

continuump

stransitionE

)()()()()( 321 ECauchyECauchyECauchyEArctgEf



Nb. Sample E0[eV] Γ0 [eV] E1-E0 [eV] Γ1 [eV] E2-E0 [eV] Γ2 [eV] E3-E0 [eV] Γ3 [eV]0 Au foil 11918.0 5.93 14.52 18.84 26.86 8.17 49.50 21.051 Au/LaOx/Al2O3 11913.7 7.39 16.17 - 28.51 10.6 51.54 16.122 Au/ZnO/MgO/Al2O3 12709.7 4.30 14.72 4.139 28.70 14.8 50.73 16.473 Au/CuO/Al2O3 11914.4 4.63 16.17 12 28.29 9.07 51.54 17.874 Au/CeOx/Al2O3 11909.2 7.50 16.17 - 29.74 3.16 52.58 8.035 Au/ZnO/Al2O3 11915.0 4.97 14.91 8.45 27.48 9.27 50.31 17.86 Au/TiO2 11908.6 4.84 15.75 10.45 29.74 14.3 52.80 26.877 Au/MnOx/Al2O3 11913.7 - 15.75 - 28.51 - 51.96 -8 Au/Al2O3 11909.7 6.14 15.94 - 29.54 6.84 51.96 18.879 Au/CeOx/ZrOx/Al2O3 11909.1 4.98 17.40 12.13 29.93 9.99 53.41 25.55

10 Au/Li2O/CeOx/Al2O3 11908.0 5.86 18.01 8.61 30.15 9.16 53.41 20.2011 Au/Rb2O/CeOx/Al2O3 11907.6 7.13 18.62 - 31.38 7.51 53.41 12.97

Transition probability parameters (LTransition probability parameters (LIIIIII edge) edge)

N. Aldea, V. Rednic, S. Pintea, P. Marginean, B. Barz, A. Gluhoi, B. E. Nieuwenhuys, M. Neuman, X. Yaning, F. MateiLocal, global and electronic structure of supported gold nanoclustersdetermined by EXAFS, XRD and XPS sent for publication Superlattices and Microstructures, Ref: SM08-141, 2008

M. LAZAR, V. ALMASAN, S.PINTEA, B. BARZ, C. DUCU, V. MALINOVSCHI, X. YANING, N. ALDEAPreparation and structural characterization by XRD and XAS of the supported gold catalystsJOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 10 (9), 2244 (2008)



C2.2.2C2.2.2 Supported Ni catalysts Supported Ni catalysts

8000 8200 8400 8600 8800 9000 9200 9400

Ab

sorp

tion

co

effi

cie

nts

Energy [eV]

Ni standard

1

2

3

4

5

XAS signalsXAS signals

8000 8200 8400 8600 8800 9000 9200 9400

Ab

sorp

tion

co

effi

cie

nts

Energy [eV]

6

7

8

9

10

8000 8200 8400 8600 8800 9000 9200 9400

Ab

sorp

tion

co

effi

cie

nts

Energy [eV]

11

12

13

14

15

8000 8200 8400 8600 8800 9000 9200 9400

Ab

sorp

tion

co

effi

cie

nts

Energy [eV]

16

17

SampleCoordination number

N1±ΔN1

Shell radius R1±ΔR1[Å]

Shift energyE0±ΔE0[eV]

Ni standard 12 2.49 8333.915Ni85 Cr15 350 0C 10.32±0.11 2.497±0.003 8334.252±0.0054

420 0C 10.18±0.09 2.485±0.003 8334.064±0.0196650 0C 10.85±0.04 2.480±0.001 8334.115±0.0503850 0C 11.19±0.043 2.490±0.001 8334.371±0.0046950 0C 11.52±0.05 2.504±0.001 8334.029±0.0075

Ni70 Cr 30 350 0C 8.89±0.083 2.511±0.003 8334.334±0.0211650 0C 10.17±0.068 2.497±0.002 8333.986±0.0001750 0C 10.44±0.052 2.501±0.002 8333.772± 0.0110900 0C 11.07±0.046 2.489±0.001 8334.069±0.0033950 0C 11.09±0.058 2.499±0.002 8333.983±0.0003

Ni85 Al 15 350 0C 6.237±0.060 2.476±0.004 8334.164±0.1456550 0C 6.671±0.121 2.541±0.006 8333.973±0.1691750 0C 8.682±0.160 2.552+0.005 8334.380+0.3152850 0C 9.635±0.082 2.514±0.003 8334.004±0.0633

1050 0C 10.802±0.056 2.492±0.066 8334.272±0.0324Ni70 Al 30 950 0C 8.241±0.088 2.518 ±0.004 8334.003±0.0857Ni60 Al 40 10500C 9.862±0.059 2.504±0.002 8333.972±0.0356



S. Pintea, V. Rednic, P. Marginean, X. Yaning, H. Tiandou, Z. Wu, M. Neumann and N. AldeaCrystalline and electronic structure investigated by XRD, XAS and XPS methods of Ni nanoclusters supported on Al2O3 and Cr2O3

sent for publication Superlattices and Microstructures, Ref: SM 08-136, 2008

The first coordination shell parametersThe first coordination shell parameters



C2.2.3.C2.2.3. Fe3O4 polypyrrole core-shell composites

(A) quadrupole transition 1s-3d, l=o, ±1, ±2

(B) dipole transition 3d-4d mixing Fe electrons, l=o, ±1

(C) d-p mixing Fe and O electrons

(D) clusters size of metal oxide

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

7100 7110 7120 7130 7140 7150 7160 7170

miu

x(e

ne

rgy

)

X-ray energy [eV]

The first and second derivatives of Fe3O4 XANES signal

the first derivativethe second derivative

Fe3O4 standard sample

Threshold energy EB- maximum value of the first derivative

Full multiple scattering theory applied to transition metals and AB compounds

N. Aldea, C. Tiusan, A. Chezan, Physica B, 208-209 (1995),691

Fe K edge XANESFe K edge XANES



-0.05

-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06

4 6 8 10 12 14 16

Chi(k)

wave vector [1/A]

Fe3O4 Chi signal of standard sample

Chi EXAFS signalFe3O4 χ signal of standard sample

0

0.2

0.4

0.6

0.8

1

6800 7000 7200 7400 7600 7800 8000 8200

miu

x(e

nerg

y)

X-ray energy [eV]

Fe3O4 - Normalized EXAFS & XANES

normalized EXAFS

Fe3O4 Normalized XANES & EXAFS

0

0.2

0.4

0.6

0.8

1

6800 7000 7200 7400 7600 7800 8000 8200

miu

x(en

ergy

)

X-ray energy [eV]

Fe3O4 - Normalized EXAFS & XANES, Miux-0, Miux

Normalized EXAFS signal Fe3O4 XANES

Fe3O4 miux Fe3O4 miux-zero

Fe3O4, µ0, µ signals

-2.4-2.2

-2-1.8-1.6-1.4-1.2

-1-0.8-0.6-0.4-0.2

6800 7000 7200 7400 7600 7800 8000 8200

miu

x(en

ergy

)

X-ray energy [eV]

"fe3o4s.dat"background

Fe3O4 as standard sample

XAS signalsXAS signals



0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 1 2 3 4 5

F

ourier

Tra

nsfo

rm M

odule

k**

n*c

hi(k)*

wf(

k)

Interatomic distances [A]

CDXAS

A. San-Miguel, Physica B 208 & 209,177 (1995) (LURE, ESRF)

CDXAS computer package programs

Radial structure function (RSF).)2(exp)()()( dkrikkWFkkr n

Inverse Fourier transform of the RSF j

j

R

R

nj drrkirkWFkk

2

1

)2exp()()(/1)(

.

Where are the first & second coordination shells?

They are overlapped k r

Modified Filon algorithm M. Abramowich and A. Stegun, Handbook Math. Func., EXAFS 51-65 (1996)

What we have to do?

Good bye FFT !!!

EXAFS resultsEXAFS results

N. Aldea, E. Indrea, Comput. Phys. Commun. 60 (1990) 155. N. Aldea, R. Zapotinschi, PC 94 Lugano, Switzerland, (1994)



0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1 2 3 4 5

F

ourier

Tra

nsfo

rm M

odule

k**

n*c

hi(k)*

wf(

k)

Interatomic distances [A]

Fe3+ tetrahedral structure Fe-O R1=1.89 Å, N1=4

Fe2+/ Fe3+ octahedral structure Fe-O R2=2.09 Å, N2=6

R = R2-R1= 0.2 ÅR[H] = 0.52147 Å

N. Aldea, R. Turcu, A. Nan, I. Craciunescu, O. Pana, X. Yaning, Z. Wu, D. Bica, L. Vekas, F. MateiInvestigation of nanostructured Fe3O4 polypyrrole core-shell composites by X-ray absorbtion spectroscopy and X-ray diffraction using synchrotron radiationaccepted for publication Journal of Nanoparticle Research, DOI: 10.1007/s11051-008-9536-3

N. Aldea, S. Pintea, V. Rednic, F. Matei and X. YaningComparative study of EXAFS spectra for closed-shell systemssent for publication JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS

2HRR



Radial distribution functionRadial distribution function



Sample

The first shell The second shellE0± E0

Shiftenergy (eV)

N1 ± N1

Atoms numbers

R1 ± R1

Shell radius (nm)

N2 ± N2

Atoms numbers

R2 ± R2

Shell radius (nm)

Fe3O4 4 0.189 6 0.209 7123.75±0.15

F10 2.46±0.03 0.189±0.001 5.93±0.03 0.210±0.001 7116.27±0.46

F12 3.11±0.009 0.188±0.001 5.15±0.01 0.209±0.001 7118.35±0.43

F14 3.16±0.03 0.190±0.001 5.25±0.01 0.209±0.002 7114.10±0.51

Local structure parametersLocal structure parameters

C3.C3. XRD measurements XRD measurements


CONTROLLER

SMC

Time gen.

COUNTER

DISPLAY

GATED CLOCK

I/O REGISTER

V/F

COUNTER

HV for LC

HV for Na I

SCA

Ampl.

RATEMETER

DRIVER FORTAB (6)

DRIVER FOR MONO (1)

I/V Ampl.

SMC

DRIVER FOR DIF (6)

INTERFACECOMPUTER

PDP11/53

TERMINAL

PRINTER

IC AL window

BE window

SLI

DETECTOR

SAMPLE

SLIT

MOTION TABLE

6 - CIRCLESDIFRACTOMETE

R

MONOCHROMATORMIRROR

SR BEAMLINE

CAMAC CRATE

BEPC


C3.1C3.1 XRD setupXRD setupSCHEMATIC DIFFRACTION STATION AT BSRL-2 montage, ionic chamber before sample



C3.2.1C3.2.1 Supported Gold catalysts Supported Gold catalystsC3.2C3.2 Results and discussionsResults and discussions

Au Space Group 225,a=b=c= 0.40720 nmInstrumental correction: Au - foil

3 5 4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0 8 5

( 3 1 1 )( 2 2 0 )

( 2 0 0 )

( 1 1 1 )

Re

lati

ve

In

ten

sit

ies

3

4

6

5

2

( 2 o)

3 5 4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0 8 5

( 3 1 1 )( 2 2 0 )

( 2 0 0 )( 1 1 1 )

8

9

1 0

1 1

7

Re

lati

ve

In

ten

sit

ies

( 2 o)

35 40 45 50 55 60 65 70 75 80 85

Standard sample Au foil

(111)

(200)

(311)(220)

Rel

ativ

e In

tens

ity

(2 o)

RIGAKU setup with rotating anode

λ = 0.15406 nm



Data analysis and Fourier Transform for XRLP by Data analysis and Fourier Transform for XRLP by Generalised Fermi Function (GFF) distributionGeneralised Fermi Function (GFF) distribution

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 50 100 150 200 250 300 350 400

Fou

rier

Tra

nsfo

rm o

f tr

ue s

ampl

e

L[Å]

Sample Au/SiO2 (1.1), Line (111)

ExperimentalGeneral approximation

Cubic App.Parabolic App.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 20 40 60 80 100 120 140

Fou

rier

Tra

nsfo

rm o

f tr

ue s

ampl

e

L[Å]

Sample Au/SiO2 IMP 3, Line (220)

Experimental

Parabolic App.

General approximationCubic App.

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 10 20 30 40 50 60

Fou

rier

Tra

nsfo

rm o

f tru

e sa

mpl

e

L[Å]

Sample Au/Al2O3 (3.1), Line (311)

Experimental

Parabolic App.

General approximationCubic App.

Background correction by polynomial approximation

0

500

1000

1500

2000

2500

3000

0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.752*sin()/ λ

f(x)experimental

fondgff1(x)gff2(x)gff3(x)

Rel

ativ

e In

tens

ity



Global structural parameters of the investigates samplesGlobal structural parameters of the investigates samples

Sample LineGeneral relation

Deff

[nm]<ε2> x104

0 1 2 3

Au/ZnO/MgO/Al2O3 (111) 1.6 2.06

Au/CuO/Al2O3 (311) 5.8 0.67

Au/CeOx/Al2O3 (311) 4.0 0.71

Au/ZnO/Al2O3 (311) 2.8 0.98

Au/TiO2 (311) 3.5 0.87

Au/MnOx/Al2O3 (311) 4.3 1.18

Au/Al2O3 (311) 6.3 0.68

Au/CeOx/ZrOx/Al2O3 (111) 2.1 1.96

Au/Li2O/CeOx/Al2O3 (311) 6.0 0.69

Au/Rb2O/CeOx/Al2O3 (111) 2.0 1.99



C3.2.2C3.2.2 Supported Ni catalystsSupported Ni catalysts

40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80

Re

lativ

e in

ten

sity

Diffraction angle (2 theta)

(111)x

(200)x

(220)x

(024)# (116)

#(214)

#(214)#

Ni85 Cr15 at % 350

420

650

850

950

42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80

Re

lativ

e in

ten

sity


(111)x

(200)x

(220)x

(024)#

(116)#

(214)#

(300)#

Ni70 Cr30 at % 350

650

750

900

950

42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80

Re

lativ

e in

ten

sity


(111)x

(200)x

(220)x

Ni85 Al15 at % 350

550

750

850

1050

42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80

Re

lativ

e in

ten

sity


(111)x

(200)x

(220)x

(113)#

(116)#

(214)#

(300)#

Ni70 Al30 at % 950

Ni60 Al40 at % 1050

XRD Paterns measured on syncrotron radiation



Grhkl 2Grhkl 2 Grhkl 2


Sample

(111) (200) (220)

DGr[Å]×104

DSch[Å] DGr[Å]×104

DSch[Å] DGr[Å] ×104

DSch[Å]

Ni85Cr15 at% 3500C 105 0.3863 114 89 0.4817 89 93 0.2089 93

4200C 105 0.3863 114 89 0.4814 89 88 0.2355 89

6500C 364 0.0158 571 281 0.0326 308 305 0.0046 571

8500C 406 0.0082 571 385 0.0104 571 419 0.0012 800

9500C 461 0.0056 800 409 0.0084 571 430 0.0011 800

Ni70Cr30 at% 3500C 131 0.2706 138 169 0.1214 174 132 0.0892 148

6500C 279 0.0491 308 213 0.0639 235 205 0.0210 267

7500C 362 0.0162 571 299 0.0258 364 251 0.0057 444

9000C 397 0.0097 571 361 0.0131 444 345 0.0018 800

9500C 420 0.0071 800 402 0.0087 571 433 0.0010 800

Ni85Al15 at% 3500C 67 0.7188 82 80 0.4989 89 57 0.5145 62

5500C 86 0.6814 85 77 0.5937 82 67 0.3972 70

7500C 188 0.1132 211 145 0.1674 148 152 0.0589 174

8500C 254 0.0485 308 201 0.0804 211 207 0.0215 267

10500C 383 0.0108 571 338 0.0174 444 350 0.0023 800

Ni70Al30 at% 9500C 225 0.0699 267 202 0.0782 211 179 0.0367 211

Ni60Al40 at%10500C 313 0.0220 444 298 0.0260 364 269 0.0072 444



C3.2.3C3.2.3 Fe3O4 polypyrrole core-shell composites

Nanoparticles Fe3O4 polypyrrole core-shell composites

Silicon powder for instrumental correction




Sample

(hkl)h

(nm-1)

f

(nm-1)

Deff

(nm)< ε2>hkl10-3 DSch

(nm)

F10

220 0.29265 0.28281 3.8 0.60412 7.1

311 0.24391 0.24124 4.9 0.32241 8.3

400 0.19837 0.19706 6.1 0.14891 10.1

511 0.23592 0.23522 5.1 0.12552 8.5

440 0.23454 0.23228 5.1 0.10411 8.6

F12

220 0.28657 0.28299 4.1 0.61115 7.1

311 0.21685 0.21492 5.5 0.25617 9.3

400 0.25166 0.24716 4.6 0.23244 8.1

511 0.18403 0.18182 6.4 0.07421 11

440 0.27229 0.22705 3.2 0.08862 8.8

F14

220 0.15342 0.15079 7.7 0.16925 13.3

311 0.12811 0.12269 8.7 0.07882 16.3

400 0.11459 0.11424 10.3 0.04793 17.5

511 0.15418 0.15387 7.8 0.05282 13

440 0.12575 0.11126 7.7 0.02281 18



C4.C4. XPS measurements XPS measurements

C4.1C4.1 Supported Ni catalystsSupported Ni catalysts

Background correction for XPS profiles was done by Shirley-Tougaard approximation

XPS profiles were approximated by Doniach-Sunjic distribution: 2

122

arctan)1(2

cos

),,:(

exf

f

ex

efxDS

Ni 2p core level lines O 1s core level lines

Ni 2p3/2 metalNi 2p3/2 oxideNi 2p1/2 oxide

satellitesNi metal is missing Contribution from

Cr2O3 and Al2O3



C4.2C4.2 SupportedSupported Gold catalystsGold catalysts

Au(Au2O3)/Li2O/CeO2/Al2O3

Ce

3d

O 1s

Survey

Au 4f

Evidence of Au2O3 on the

surface!



Au/ CeO2/Al2O3

O 1sSurvey

Au 4f

metallic

state

D. Conclusions


The investigated catalysts have crystallite average sizes between 1.6 - 6.3 nm for supported Au catalysts, 6.7 – 43.3 nm for supported Ni catalysts and 3.2 – 10.3 nm in case of Fe3O4 polypyrrole core-shell composites; 1.6 nm is the smallest value of crystallite size determined by XRD method;

The small coordination obtained from EXAFS can explain the strong metal-support interaction (SMSI) as well as the active sites occurrence;

By analyzing the Au LIII edge (XANES) we have shown the existence of the electronic transitions without determining or discriminating the percentage between Au+, Au0;

The different values of the FWHM, obtained for each electronic transition, are an evident prove for the SMSI.

The microstrains of lattice can also be correlated with the effective crystallite size in the following ways: the value of the effective crystallite size increases when the microstrain value decreases, and reverse;

D. Conclusions


Until now in literature we did not find the 1st and 2nd coordination shells evidenced by XAS for Fe3O4 nanoparticles;

The Ni oxide of the precursors is totally reduced, as we can see in XRD patterns only on the surface there is a thin layer of Ni oxide, evidenced from XPS measurements.

Shapes and shift of XANES spectra and diminution of number of atoms from 1st (25 %) and 2nd (10%) from coordination shells of Fe atoms pointed out the existence of electronic interaction between magnetite nanoparticle and surrounding polypyrrole;

The XPS method provided us additional information related to electronic structure and the possible existence of the gold oxide on the surface of the gold nanocrystallites.

Research Team and collaborators


Dr. Nicolae Aldea

Dr. Petru Marginean

PhD Student Bogdan Barz

PhD Student Stelian Pintea

PhD Student Vasile Rednic

Prof. Dr. Manfred Neumann

Dr. Rodica Turcu

Dr. Florica Matei

Thank you for your attention !


Documents

N. Aldea 1, S. Pintea 1, V. Rednic 1, P. Marginean 1, R. Turcu 1, S. Gergely 1, M. Neumann 2, Y. Xie 3, F. Matei 4 1 National Institute for R&D of Isotopic