Metal nanoparticles and nanomaterials:

Radiolytic synthesis and applications

Hynd Remita

Laboratoire de Chimie Physique, CNRS-UMR 8000

Université Paris-Sud, Orsay

Radiolytic synthesis of metal clusters

H2O es-, H3O

+, H•, OH•, H2, H2O2

Selective reducing environment

• (CH3)2CH OH + H• (CH3)2C

•OH + H2

• (CH3)2CH OH + OH• (CH3)2C•OH + H2O

g, e-

Isolated atoms as precursors Homogeneous nucleation

J. Belloni, Rad. Res., 150, S9, (1998) J. Belloni et al., New J. Chem., 1239 (1998) J. Belloni, Cat.Today, 113, 141 (2007)

Cinétique de nucléation de clusters d’argent

Fast Kinetics Center Elyse

Reduction and nucleation processes studied by pulse radiolysis

e-aq + Ag+ Ag0

k = 4.8 x 1010 dm3 mol-1 s-1

Ag0 + Ag+ Ag2+

k = 8.5 x 109 dm3 mol-1 s-1

Ag2+ + Ag+ Ag3

2+ k = 2 x 109 dm3 mol-1 s-1

Ag32+ + Ag3

2+ Ag42+ + 2 Ag+

E. Janata et al., J. Phys. Chem., 98, 10888, (1994) E. Janata, J. Phys. Chem., 107, 7334, (2003)

pulse

Metal nanoparticles synthesized by radiolysis

Silver nanoparticles stabilized by PVA (polyvinyl alcohol)

Gold nanoparticles stabilized by PVA and deposited on mica

Radiolysis monodispersed particles size control

Stabilization of metal clusters by ligands or polymers

Ligands (CO, EDTA, calixarenes…)

M. Mostafavi et al., Rad. Phys. Chem., 41, 453, (1993)

Polymers (polyacrylate) *

I. Lampre et al. to be submitted. steric effect -

- -

-

- -

-

-

-

Ag n

m+

STM image of blue silver clusters

Ag73+ or Ag8

4+ (stable in air)

Ag NP stabilized by calix[8]arene

Functional group having affinity for metal NPs

Dose rate effect on size distribution of silver clusters

0 10 20 30 40 500

5

10

15

electron beam

C6+

ion beam

g rays

Percen

tage o

f p

arti

cle

s

Diameter (nm)

0

10

20

30

40

50

60

70

Percen

tage o

f p

arti

cle

s

0

5

10

15

20

25

30

Percen

tage o

f p

arti

cle

s

2200 Gy s-1

200 Gy s-1

1.75 Gy s-1

(Aqueous solution : 2 10-3 M AgClO4 , 0.1 M PVA, 0.2 M 2-propanol)

H. Remita et al., Radiat. Phys. Chem, 72, 575 (2005)

Dose rate effect on cluster size distribution

The final size depends on the dose rate At higher dose rate smaller particles are obtained

Silver particles

M. Mostafavi et al., Collaboration with CLAL,

since 1989

Nanometric Particles

(Conducting Pastes for electronics)

300-400 nm

Bimetallic nanoparticles

synthesized by radiolysis

At high dose rate,

alloyed clusters are

obtained

Dose rate effect on bimetallic cluster structure

At low dose rate, the less noble metal is coating the

core made of the more noble metal in a core-shell

structure

J. Belloni, H. Remita in Radiation Chemistry, EDP Sciences, p97-116, 2008.

Dose rate effect on bimetallic nanoparticle structure: Au-Ag system

([AuIII] = [AgI] = 5 x 10-4 M, [PVA] = 0,1 M, l = 0,2 cm) Low dose rate: 3,8 kGy.h-1

Aun/Agn core-shell

High dose rate: 35 kGy.h –1

Ag-Au Alloys

J. Phys. Chem.B, 102, 4310 (1998)

Bimetallic nanoparticles

M/N bi-layered M-N Alloy

Synthesis of nanoparticles of controlled stucture and composition

Catalytic convertors, NOX removing (Pt, Pt-Sn)

Selective hydrogenations (Pd, Pd-Au, Pd-Ag)

Fuel cells: Methanol oxidation (Pt-Ru, Pt-Au)

Ethanol oxidation (Pd-Au)

Oxygen reduction (Pt-Co, Au-Fe)

H+ reduction (Pt, Au-Fe)

Application in catalysis and fuel cells

Ksar et al. Chem. Mater., 2009, 21, 3677. R. Doherty, J. Catal. 2012, 287 , 102.

Shape control

Gold nanorods

50 nm

Gold nanorods

F. Kim et al., JACS, 2002, 124, 14316 C. J. Murphy et al., MRS Bulletin, 2005, 30, 349

Shift of the longitudinal plasmon band towards larger wavelengths with increasing the aspect ratio

PVA(H) + OH PVA + H2O

PVA(H) + H PVA + H2

2 PVA PVA-PVA (cross linking)

Formation of a hydrogel

Irradiation induces crosslinking of the polymer

Microtomie TEM montrant des NRs bien dispersés dans l’hydogel PVA

Au nanorods in PVA matrices

Polyvinyl Alcohol

Abidi, W. et al, J. Phys. Chem. C (2010) 114, 14794.

Formation of Nanofilms

X-ray radiation under grazing incidence (ESRF)

F. Muller et al., Langmuir, 20, 4791, 2004

X-ray

scattering

Incident

X-ray beam

nanofilm of Ag

x

monolayer of C 21H23-COOH (behenic acid) +

Adsorbed Ag+ ions

qin < qc 4,5 nm

slits

miror Langmuir

cuve

monochromator

Interaction of X-rays with the interface

Follow the evolution of the structure at the surface

Nanoparticles

(ligands, polymers)

Metal

Electrodes Micelles

Oxides, Carbon,

Semiconductors

Zeolites

Mesophases,

Mesoporous

Materials

Polymeric

Membranes

Carbon

Nanotubes

J. Belloni, H. Remita in Radiation Chemistry, EDP Sciences, p97-116, 2008.

Matériaux microporeux et nanoparticules métalliques:

Application aux domaines des Capteurs Chimiques

Zéolithe en Suspensions colloïdales et films minces Synthèse par voie radiolytique Etudes structurales par diffraction X aux petits angles Spectroscopies résolues en temps (photolyse et radiolyse)

a. b. c.

De la suspension colloïdale .... au film mince

Chemistry of Materials (2006), Sensors and Actuators (2007) Superlattices and Microstructures (2008) Research on Chemical Intermediate (2009)

22232 ,,,,, OHHOHHOHeOH aq

g

22222 HOHCHSCHHSHCHHOCH

OHOHCHSCHOHSHCHHOCH 22222

22222 )()(2 SCHHOCHOHCHSCH aq

HSOHCHCHeSHCHHOCH aq 2222

2

aqZn e Zn

2Zn HS ZnS H

Radiolytic Synthesis of ultra small ZnS nanoparticles

20 nm

2 nm a b

Very small ZnS nanoparticles compared to those prepared by chemical methods

A.H. Suici et al. Chem. Phys. Lett. 2006, 422, 25.

Metal nanoparticles

induced on supports

Ag-modified TiO2

20 nm

Diffuse reflectance spectra of pure and Ag-modified TiO2 (P25)

Ag+ solution + TiO2 AgNPs@TiO2

g

Surface modification of TiO2 : Decrease of electron-hole recombination

Ag NPs act electron scavengers Enhancement of the photocatalytic activity under solar light Antibacterial properties

Ag

Ag

Ag

Ag

Direct Methanol Fuel Cells: Platinum based electrocatalysts are the most efficient

Ethanol as a fuel: less toxic than methanol can be produced in large quantities from agricultural products

Pd:

very active for ethanol oxidation in basic medium much cheaper than Pt and 50 times more abundant

Direct Alcohol Fuel Cells

- Portable electronic devices

- fuel cells vehicules

Self-assembly of surfactants on carbon nanotubes (CNTs)

Mioskowski, C. et al Science 300, 775, 2003. N. Mackiewicz et al., J. Am. Chem. Soc., 130 , 8110, 2008.

Carbon Nanotube Functionalization

Collaboration with E. Doris and N. Mackiewicz, CEA, Saclay

N+

6Cl

Pd/CNTs: application in fuel cells

Curant Intensity : 25 times higher (3540 mA·cm−2· mg−1) than the best

intensities reported in the literature

N. Mackiewicz et al., J. Am. Chem. Soc., 130, 8110, 2008.

Electrocatalysts for ethanol oxidation

PdII Reduction by electron beams (dose rate: 2200 Gy s-1)

(111)

(200)

(220)

(311)

Metal nanostructures induced in hexagonal mesophases

Mesophases

Micellar cubic

Contineous cubic

Lamellar

Micelles

Micellar cubic

Hexagonal

Concentration in surfactant wt%

Temperature

Soft templates for nanomaterial synthesis 1D, 2D or 3D nanomaterials with new optical, electrical, magnetic, mechanical properties

5<D<35 nm

Cyclohexane

eau + sel métallique

- Radiolyse en milieu confiné - Mésophase : matrices molles Mieux contrôler la croissance des nano-objets (structure 1D, 2D, 3D) Synthèse en phase aqueuse ou en phase non-aqueuse

Synthèse de nano-objets en mésophase

Chem. Mater. 2009, 21, 1612-1617; Chem. Mater. 2009, 21, 5170. New J. Chem. 2012, 36, 2135. Adv. Funct. Mater. 2012, 22, 4900. Communication INC:, En direct des laboratoires de l’institut de chimie du CNRS (2012)

Pd Nanowires: Application in Ethanol Oxidation

Complete Oxidation Reaction of ethanol:

CH3CH2OH + 3 H2O → 2 CO2 + 12 H+ + 12 e-

Reactions in alcalin media:

CH3CH2OH + 3 OH- → CH3COads + 3 H2O + 3 e-

OH- → OHads + 1 e- CH3COads + OHads → CH3COOH CH3COOH + OH- → CH3COO- + H2O

Pd nanowires: very efficient in ethanol oxidation

Very stable with cycling Application in fuel cells

G. Surendran et al., J. Phys. Chem. C., 2008, 112, 10740

KOH 1M

-1000 -800 -600 -400 -200 0 200 400 600

-333

0

333

666

999

1332

1665

1998

2331

I / m

A c

m-2m

g-1

E / mV vs. Hg/HgO

1st cycle

200th

cycle

1 M EtOH, 1 M KOH, 50 mV s-1

Synthesis in CTAB-based hexagonal mesophases Irradiation by electron beams

Polymer nanostructures

Fibers: interactions byp-stacking Globular Structures H bonds interactions

HO. N3.

EDOT

50 nm

50 nm

Cryo-TEM Cryo-TEM

Control of the Morphology

EDOT PEDOT

g rays electrons

Conducting polymers :

Radio-polymerization in a position

Application as Sensors

J. Phys. Chem. B 2012, 116, 1467--81 Radiat. Phys. Chem. 2013, 82, 44-53

Polymerization in the hexagonal mesophase

The parameters of the hexagonal mesophase are not affected by the irradiation

Ghosh et al. Nature Materials (2015) 14, 505 – 511

Ar

Ar Ar

*

ArAr

Ar

Ar

*

Ar

n

1,4-diphenylbutadiyneAr = Phenyl group

Poly(diphenylbutadiyne)(PDPB)

h

polymerization

b

Extraction of the PDPB polymer nanostructures (addition of ethanol+H2O)

300 nm

g -polymerization

Polymer Nanowires of tunable diameters

Polymerization in hexagonal mesophases

Application in photocatalysis Ghosh et al. Nature Materials (2015) 14, 505 – 511

In bulk

Conclusion

• Radiolysis is a powerful method to synthesize metallic,

semiconductor, polymer nanostructure sand composite materials

• Radiolysis is a powerful method to synthesize bimetallic nanoparticles and nanostructured materials of controlled composition, structure, size and shape

• Soft templates can be used as nanoreactors to design (2D and 3D)

nanomaterials of different shapes • Application catalysis, photocatalysis, electrocatalysis (fuel cells),

sensors…

Thank you for your attention…

Acknowledgements

Mehran Mostafavi (LCP, Univ. Paris-Sud) Jean-Louis Marignier (LCP, Univ. Paris-Sud) Isabelle Lampre (LCP, Univ. Paris-Sud) Jacqueline Belloni (LCP, Univ. Paris-Sud) Samy Remita (LCP, Univ. Paris-Sud) Christophe Colbeau Justin (LCP, Univ. Paris-Sud)