Markus Niederberger Laboratory for Multifunctional …...Markus Niederberger Laboratory for...

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Markus Niederberger Laboratory for Multifunctional Materials Department of Materials ETH Zürich [email protected]

Transcript of Markus Niederberger Laboratory for Multifunctional …...Markus Niederberger Laboratory for...

Page 1: Markus Niederberger Laboratory for Multifunctional …...Markus Niederberger Laboratory for Multifunctional Materials Department of Materials ETH Zürich Markus.Niederberger@mat.ethz.ch

Markus Niederberger

Laboratory for Multifunctional Materials

Department of Materials

ETH Zü[email protected]

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(Co(Co--))PrecipitationPrecipitation

SolSol--GelGelChemistryChemistry MicroMicro--

emulsionsemulsions

HydroHydro-- & & SolvothermalSolvothermalProcessingProcessing

BiomimeticBiomimeticSynthesisSynthesis

TemplateTemplateSynthesisSynthesis

OverviewOverview

MicrowaveMicrowaveSynthesisSynthesis

LiquidLiquid--Phase Phase RoutesRoutes to to InorganicInorganic

NanopowdersNanopowders

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AdvancesAdvances inin……

HotHot--InjectionInjection MethodMethod

Times Cited: 26151) Injection of a „cold“ precursor solution to a hot (molten) surfactant or surfactant/solvent

mixture

2) Nucleation and growth

3) Surfactant controls size, shape, and surface properties

4) Precipitation by addition of a „nonsolvent“

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„„ConsequencesConsequences““ of of thethe HotHot--InjectionInjection MethodMethod::

SurfactantSurfactant--DirectedDirected NonhydrolyticNonhydrolytic RoutesRoutes

AdvancesAdvances inin……

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SynthesisSynthesis

Metal Salts: Chlorides MCln, Acetates M(OOCCH3)n, Nitrates M(NO3)n,…

Metal Organic Compounds: Metal Alkoxides M(OR)n,..

Organometallic Compounds: Metal Carbonyls M(CO)n,…

„Molecular“ Precursor(s) +Molten Surfactant(s)

Surfactant(s)/High Boiling Solvent(s)

T = 100 – 350 °C

Inorganic Nanoparticles

Diphenyl ether (C6H5)2O

Boiling Point: 259 °C

Trioctylphosphine oxide (TOPO)

Melting point: 201 °C

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ShapeShape ControlControl

ButBut:: No No PredictionPrediction possiblepossible!!

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SizeSize ControlControl

Fe(CO)5 + dioctylether + oleic acid at 100 °C: Formation of Fe nanoparticle seeds (4 or 8 nm)

Addition of Fe(CO)5 solutionto the preformed seeds

Oxidation in air: γ-Fe2O3 (maghemite)

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SizeSize ControlControl

6 nm

11 nm10 nm

9 nm8 nm7 nm

13 nm12 nm

Hyeon et al., Angew. Chem. Int. Ed. 2005, 44, 2872

PredictionPrediction possiblepossible!!

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„„MolecularMolecular““PrecursorPrecursor

OrganicOrganicSolventSolvent

TemperatureTemperatureTreatmentTreatment

Metal Oxide Metal Oxide NanoparticlesNanoparticles

Without Surfactants!!!

OurOur ResearchResearch

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„„MolecularMolecular““PrecursorPrecursor

OrganicOrganicSolventSolvent

TemperatureTemperatureTreatmentTreatment

Metal Oxide Metal Oxide NanoparticlesNanoparticles

Without Surfactants!!!

OurOur ResearchResearch

+ Low amount of organic impurities

Nontoxic solvent vs. toxicity of surfactants

Simple, robust, and generally applicable synthesis protocol

Small number of initial components: Study of the mechanisms!

Good accessibility of the nanoparticle surface

- Less control over size and shape

Broader size distribution

Formation of agglomerates, limited redispersibility

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BENZYL ALCOHOLBENZYL ALCOHOL

Metal Chlorides:Metal Chlorides:TiO2, VO1.52(OH)0.77,

WO3·H2O, SnO2, HfO2, Ta2O5, Nb2O5

Metal Metal AcetylacetonatesAcetylacetonates::Fe3O4, Mn3O4, ZnO, Co-doped ZnO

Metal Metal AcetatesAcetates::CoO, Fe3O4, MnO, ZnO

Alkoxides + Alkoxides + AcetylacetonatesAcetylacetonates::Indium Tin Oxide (ITO), Mn-doped ZrO2,

Co/Fe-doped TiO2

AcetatesAcetates + + AcetylacetonatesAcetylacetonates::MnFe2O4, CoFe2O4, NiFe2O4

Metal Alkoxides:Metal Alkoxides:TiO2, V2O3, W18O49, SnO2, HfO2, In2O3, Ln2O3, CeO2, ZrO2, ZnO,

Ta2O5, Nb2O5, NaNbO3, NaTaO3, BaTiO3, SrTiO3, (Ba,Sr)TiO3,

LiNbO3, BaZrO3

AcetylacetonatesAcetylacetonates + Chlorides:+ Chlorides:InNbO4, MnNb2O6, YNbO4

OurOur ResearchResearch

AcetatesAcetates + + Alkoxides:Alkoxides:

CdIn2O4

Angew. Chem. Int. Ed. 2008, 47, 5292

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BinaryBinary Metal Oxide Metal Oxide NanoparticlesNanoparticles

Metal ChloridesMetal ChloridesT = 60-220 °C

Metal AlkoxidesMetal AlkoxidesT = 200-250 °C

BENZYL ALCOHOLBENZYL ALCOHOL Metal Metal AcetylacetonatesAcetylacetonates

T = 80-200 °C

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TernaryTernary Metal Oxide Metal Oxide NanoparticlesNanoparticles

M(acac)M(acac)33 and and NbClNbCl55 BENZYL ALCOHOLBENZYL ALCOHOL Alkoxides and Alkoxides and

AcetylacetonatesAcetylacetonates

Indium Tin Oxide 10 wt% SnO2

Metal AlkoxidesMetal AlkoxidesT = 200-250 °C

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Chemical Formation Chemical Formation MechanismsMechanisms

ExampleExample::Formation Formation MechanismMechanism of BaTiOof BaTiO33

No No waterwater TwoTwo mainmain questionsquestions::

1) Where does the oxygen come from?

2) How is it transferred from the source to themetal center?

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Chemical Formation Chemical Formation MechanismsMechanisms

? =

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Chemical Formation Chemical Formation MechanismsMechanisms

O-TiOH

C-C Bond Formation!

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Chemical Formation Chemical Formation MechanismsMechanisms

The oxygen isprovided by the „OH“

group of benzylalcohol!

J. Am. Chem. Soc. 2004, 126, 9120

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Chemical Formation Chemical Formation MechanismsMechanisms

Chem. Eur. J. 2006, 12, 7282

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Chemical Formation Chemical Formation MechanismsMechanisms

To understand nanoparticle formation on a molecular level (i.e., crystallization and size- and shape-determining parameters), all the organic species (initially present as

well as formed in-situ) have to beconsidered!

J. Mater. Chem. 2008, 18, 1171

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AssemblyAssembly

NanoparticlesNanoparticles as Building Blocks (as Building Blocks (LegoLego BricksBricks))

Shevchenko, Talapin, Murray, O’Brien: J. Am. Chem. Soc. 2006, 128, 3620

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AssemblyAssembly

NanoparticlesNanoparticles as Building Blocks (as Building Blocks (LegoLego BricksBricks))

Nature, 439, 55-59 (2006)

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AssemblyAssembly

NanoparticlesNanoparticles as Building Blocks (as Building Blocks (LegoLego BricksBricks))

Chaudret et al. Science 2004, 303, 821

500 nm 10 nm

New Properties?

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ApplicationsApplications

Metal Oxide Metal Oxide NanoparticlesNanoparticles forfor Gas Gas SensingSensing

3 mm 3 mm

6 m

m

Front sidegold electrodes

Back sideplatinum contacts

Cross section

0.38

mm

Alumina substrate

Sensing layer

50 μm

In2O3

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ApplicationsApplications

Metal Oxide Metal Oxide NanoparticlesNanoparticles forfor Gas Gas SensingSensing

100 150 200 250 300

10

100

I Air/I NO

2

Temperature (°C)

2 ppm NO2

a)

2 4 6 810-9

10-7

10-5

10-3

T= 250°C

Cur

rent

(A)

T ime (h)

b)

0

10

20

30

40

50

60

[NO

2] (pp

m)

1 1010

100

slope= (0.49±0.06) ppm -1

lower detection limit ~ 1 ppb

T= 250°C

I Air/I NO

2

[NO2] (ppm)

c)

(a) Response to 2 ppm of NO2 versus operating temperature of the In2O3 sensor: Maximum sensitivity around 200°C

(b) Dynamic response at 250°C to different and successive concentration pulses of NO2 (2-20 ppm): Fast response time (less than 60 s)

(c) Calibration curve at 250°C: Detection limit of about 1 ppb for NO2 in air

Cross-sensitivity tests with CO and CH4 show no response (T = 100-400°C)

Angew. Chem. Int. Ed. 2004, 43, 4345

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ConclusionsConclusions -- OutlookOutlook

Metal Oxides Metal Oxides NanoparticlesNanoparticles

Synthesis in Benzyl Alcohol:

General (> 30 Compositions)

Large Variety of Crystal Sizesand Shapes: Wires, Rods,

Platelets, Cubes, Spheres,…

SynthesisSynthesis

AssemblyAssembly

But: Doping, Multi Metal Oxides, Heteronanostructures!

But: No Prediction! No Rational Synthesis Planning!

1, 2 and 3D Architectures in Selected Cases

But: Dispersions of Nanoparticles on

Primary Particle Level!

But: Nanoparticles as Artificial Atoms

(Directed Bonding)

Nanocomposites / Organic-Inorganic Hybrid Structures

But: Study of Collective Properties

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MultifunctionalMultifunctional MaterialsMaterials

2007