state-of-the-art flame synthesis of nanoparticles · state-of-the-art flame synthesis of...

State-of-the-art Flame Synthesis of Nanoparticles

Dr. Frank Ernst

ernst@ptl.mavt.ethz.ch

Particle Technology Laboratory,

Department of Mechanical and Process Engineering

ETH Zurich, www.ptl.ethz.ch 200 nm

Verbrennung und chemisch reaktive Prozesse in der Energie- und Materialtechnik

2

1 - 100 nm (at least into two dimensions)

The thickness (diameter) of a

human hair is 50,000 - 100,000 nm!

Nanoparticles

3

4

Melt

ing

Po

int,

K

Particle diameter, Å

Au

Buffat and Borel, Phys. Rev. A 13, 2287 (1976)

The Melting Point Decreases

with Decreasing Nanoparticle Size

5

Large surface area per gram

(adsorbents, membranes)

Stepped surface at the atomic level (catalysts)

Easily mix in gases and liquids (reinforcers)

Superfine particle chains (recording media)

Easily carried in an organism

(new medicines)

Cosmetics that last way into the night ...

Some people believe that nanoparticles are

a new state of matter!

10 mm

10 nm

SSA = 0.2 m2/g

SSA = 200 m2/g

Applications of Nanoparticles

6

How are they made?

Many processes & synthesis conditions…

Plasma-arc

Laser ablation

Chemical Vapor Deposition

Wet-phase chemistry

etc.

Need synthesis technique that is:

Rapid, continuous & scaleable

Flame synthesis…

carbon black

TiO2

SiO2

C60/C70

Scale-up

limitations

106 t/year

103 t/year

7

TiCl4

TiCl4

TiCl4 H2

H2 H2 O2

O2 O2

TiO2

TiO2

TiO2 TiO2

H2O

H2O H2O

HCl

HCl

Particle formation & growth – flames

Chemical reaction

Nucleation

Aggregation

Coagulation

25

00

20

00

15

00

10

00

50

0

T (K)

8

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fw Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Ac

La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Vapor flames

Can make many interesting materials:

Fillers for composites, catalysts etc.

However, limited compositions

C, TiO2, SiO2, Al2O3

9

TiCl4

TiCl4

TiCl4 H2

H2 H2 O2

O2 O2

TiO2

TiO2

TiO2 TiO2

H2O

H2O H2O

HCl

HCl

Vapor flames

Chemical reaction

Nucleation

Aggregation

Coagulation

25

00

20

00

15

00

10

00

50

0

T (K)

Reactants in vapor phase

10

Spray flames

Reactants in LIQUID phase

Keep aerosol processes

Dispersed

Product-

Molecules

& Cluster

Droplets contain:

- Organic solvent (comb. energy)

- Reactant precursor compound

11

Spray flames

12

Flame synthesis

Dispersed

Product-

Molecules

& Cluster

30

mm

300 nm

Vapor Flame Spray Flame

200 nm

Mädler, L., Kammler, H.K., Mueller, R., and Pratsinis, S.E., J. Aerosol Sci. 33 (2) 369-389 (2002).

13

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fw Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Ac

La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Spray Flame Pyrolysis (FSP)

Liquid enables composition flexibility

Opens up many possibilities…

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fw Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Ac

La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Spray flames

14

Single-phase particles & aggregates

Mixed-phase & composition

Embedded, surface clusters & shells

Surface functionalization

Formulations

Immobilization, films & 2D coatings

Devices

15

Tailor-made particle structures

(size, morphology, crystallinity etc.)

with a large variety chemical compositions

16

Flame Spray Pyrolysis

17

Au on TiO2

15 nm

Mädler, L., Stark, W.J., Pratsinis. S.E., J. Mater. Res., 18 (1), 115-120 (2003).

In-situ deposition of noble metals

For applications in

catalysts

sensors

optical devices, etc.

18

Au wt%

4.02.01.0

Aver

age

cryst

al s

ize,

nm

0

5

10

15

20

Au / TiO2 (~ 100 m2/g)

Concentration vs. crystallite size

Mädler, L., Stark, W.J., Pratsinis. S.E., J. Mater. Res., 18 (1), 115-120 (2003).

Doubling gold concentration

doubles Au crystallite size

leaves support unchanged

19

Au wt%

4.02.01.0

Aver

age

cryst

al s

ize,

nm

0

5

10

15

20

Au / TiO2 (~ 100 m2/g)

Au / SiO2 (~ 320 m2/g)

Concentration vs. crystallite size

Doubling gold concentration

doubles Au crystallite size

leaves support unchanged

Gold particle size is independent of ceramic supporting surface area

Mädler, L., Stark, W.J., Pratsinis. S.E., J. Mater. Res., 18 (1), 115-120 (2003).

20

Flame Spray Pyrolysis

21

Glucose sensor Proton Exchange

Membrane

Fuel Cell

detection of

• hydrogen peroxide

• biomolecules (glucose,

choline, ...)

• hydrogenation

• oxidation

• reforming

• electrodes for fuel cells

www.minimed.com www.gavial.com

Ernst et al., J. Mat.Chem., 20 (6), 2117-2123 (2008).

22

time (min)

0 20 40 60 80 100

Cyclo

hexene c

onvers

ion (

%)

0

20

40

60

80supported(12 wt% Pt)

reference(5 wt% Pt)

supported(10 wt% Pt)

embedded(2.6 wt-%)

Hydrogenation of cyclohexene

Ernst et al., J. Mat.Chem., 20 (6), 2117-2123 (2008).

23

Single-phase particles & aggregates

Mixed-phase & composition

Embedded, surface clusters & shells

Surface functionalization

Formulations

Immobilization, films & 2D coatings

Devices

24

120°C

500°C Oxygen

Methane

Oxygen

Oxygen

Precursor liquid

Syringe pump

MFCs

Exhaust ventFilter housing

Spray flame

Support flame

Shield gas

PIPI

Water inWater out

Deposition

substrate

sensing area: 7 x 3.5 mm2

Mädler et al., European patent, Dec. 9th 2004.

Direct deposition on sensor substrate

25

500 mm

SnO2

Deposition time: 180 s

Layer morphology – top view

26

500 mm

SnO2

5 mm

Deposition time: 180 s

Layer morphology – top view

27

Al2O3 5 mm

SnO2

Deposition time: 180 s

Layer morphology – cross section

28

Single-phase particles & aggregates

Mixed-phase & composition

Embedded, surface clusters & shells

Surface functionalization

Formulations

Immobilization, films & 2D coatings

Devices

29

Examples for FSP materials

50 nm

5 nm

Mädler, et al., J. Appl. Phys (2002).

Stark, W. J. et al., A., Chem. Commun. (2003).

Strobel, R. et al., J. Catal. (2003).

Metal oxides

SiO2, TiO2, Al2O3,

Bi2O3, CeO2, ZnO

Mixed metal oxides

SiO2/TiO2 ,V2O5/TiO2,

ZnO/SiO2, Zn2SiO4,

BaTiO3, CexZr(1-x)Oy

Noble metals

on oxides

Au, Pt, Pd on

TiO2, SiO2, Al2O3

200 nm Versatile Process

TiO2

Bi2O3

hollow

CexZr(1-x)Oy

ZnO/SiO2

Pt on

Al2O2

30

Mueller et al., Chem. Eng. Sci., 58 (10), 1969 - 1976 (2003).

Scale-up

40 cm

HMDSO/EtOH spray flame

producing 300 g/h of silica.

31

70

50

30

10

BE

T-e

qu

iva

len

t d

iam

ete

r, n

m

12009006003000

Production rate, g/h

1.26 M

3.0 M

4.7 M

Vapor Flames*

Oxygen12.5 l/min 50 l/min

SiO2 -

Scale-up

40 cm

HMDSO/EtOH spray flame

producing 300 g/h of silica. Mueller et al., Chem. Eng. Sci., 58 (10), 1969 - 1976 (2003).

32

Nanoparticles for Materials

Flame Spray Pyrolysis & metal-oxide materials Vapor Spray flame: extend range of accessible

compositions

Flame Spry Pyrolysis (FSP)

Metal-oxide nanomaterials for many applications

Metal on metal-oxides

Sensors and emerging areas…

Nanoparticle Technology is a frontier for scientific

advances and business opportunities

Lecture summary