1. MFNP & Optical methods
- in situ UV-vis growth monitoring
- global approach to separation and
analysis
- applied NP - ligand strategies
Eco/Life sciences:
- surface chemistry,
- plasmon, luminescence
Inorganic nanoparticulate materials:
Characterization and applications
L. Spanhel
3. ICT sector
(Information and communication technology)
- Transparent conductors
- electrochromy/electroluminescence
- planar wave guides and web amplifiers
4. Fractal approach to analysis
- introduction to fractals
- concept of fractal dimension
- examples of Df determination
2. Solar sector
- NP-thermodynamics/kinetics
- Photocatalysis
- Solar cells
L. Spanhel
Ch 1. Optical monitoring, total analysis and tailoring
multifunctional nanoparticles MFNP (sizes << 100 nm)
Absorption
Scattering
(Rayleigh, Hyper-Rayleigh), Raman
nD
l
Fluorescence
Lasing
Transmission
new excitation
Incident wave
SPR: surface plasmon
(metals or doped oxides)
“exciton”e
e
e
e e
Multi-electron
emission
e+
l/2 phonons
L. Spanhel
CdSe
Eg
+
+
hn
Bande
de valence
Bande
de conduction
nano
macro
Nanostructures semi-conductrices :
Le gap optique varie avec la taille des particules!!
1.7 nm
4 nm
macro
l [nm]
300 400 500 600 700
0.0
0.5
1.0
1.5
2.0
nano
E(eV) ~ 1240/ l (nm)
L. Spanhel
Optical absorption in ZnO et TiO2 ZnO
size ~ 5 nm
turbidité
singles
Aggregation
TiO2
size ~ 5 nm
L. Spanhel
Size dependent spectral shift for R(particle) < R (exciton)
“Gap-Size” correlation function
E = gap energy (eV)
µeff = effective exciton mass
er= dielectric constant
e0 = vacuum permittivity = 8,854 10-12 Fm-1
Dp, Rp = particle diameter , radius) (m)
e = elementary charge = 1,602 10-19 As
h = Planck constant = 6,626 10-34 J s
   
prpeff
bulk
gnano
R
e
R
h
eVEeVE
0
2
2
4
8.1
8 ee

 
DD
eVE
ZnO
pp
nano 2
47.835.1
37,3
:

Now even more general
L. Brus
1983
L. Spanhel
 
D
C
D
B
AeVE
ZnO
pp
nano 2
:

A,B,C: coefficients to be determined
via linear regression
 
)(
1240
nm
eVEnano
l

Optical absorption
spectrum
XRD/HRTEM
Meulenkamp’s finding, JPC B, 1998
 
DD
eVE
ZnO
pp
nano 2
29409.1
3.3
:

1.37 8.47
L. Spanhel
P = property
N = atomic number in cluster
a, b = empirical coefficients
Joshua Jortner, 1991:
Pnano(N) = Pmakro +
- b
a N
Power law relationship
1
3
3
4 
 mAp
p
Arp
a VNV
NMR
N


Number of molecules per particle
Vp =particle volume
NA = Avogadro number
Vm = molar volume
L. Spanhel
225
205
276
l (nm)
Densitéoptique
Nucleation chaos
2 nm
200 300 350l (nm)
Densitéoptique
Growth period
l [nm]
200 300 400 500 600
opt.Absorption
M4
M10 M34
Q-CdSe
Q-ZnO 2 nm 4 nm
L. Spanhel
-logDE
log N
0 1 2 3 4 5 6
logDE
-1,4
-1,0
-0,6
-0,2
0,2
0,6
ZnO
CdSe
b
aD 
 NE
a, b = ?
Physical meaning of a,b remains
to be searched !!
M4
M10
M34
Chemical elemental analysis, MS,
etc..needed to identify the clusters
L. Spanhel
Absorption laws
IT / I0 = T = e - ax
Photophysics Photochemistry
a [cm-1] = absorption coefficient
x = mean light path
a = 2,3 e / Vm
I0 IT
film
I0 IT
sol
IT / I0 = T = 10 – D.O.
Vm = molar volume
x
solvent
e [Lmol-1cm-1] = molar extinction
c [molL-1] = molarity
d = cell thickness
Recall:
L. Spanhel
200 300 350l (nm)
Densitéoptique
1 nm 2 nm 5 nm
Nucleation Growth
Eg (eV) = 1240 / l(nm) ~ f(R-2, R-1, R-b)
Optical monitoring of the particle size distribution (PDS)
0 2 4 6 8 10
0.5
1
1.5
2
particle size [nm]
vol.distr./nm-1
L. Spanhel
Structural/optical monitoring of NP’s Up-scaling processes
Precursors
in Y-shaped
micromixer
Surface modifiers
or precursors
Microfluidics
SAXS: small angle X-ray scattering (gyration size, aggregate structures)
Raman analysis of phonons (lattice and superficial molecular vibrations,
fs-Laser induced non-linear optical signals
Precursors
in T-shaped
micromixer
Linear optical signals: UV-vis/NIR absorption,
back-reflection, transmission, fluorescence
NP’s
Collection of
shape-tuned
bioactive NP’s
Laminar flow of NP’s
L. Spanhel
Spinning disc processor SDP: a way to nano-ZnO Up-scaling
Zn-precursor
LiOH, NaOH or KOH
Continuous
flow reactor
Hartlieb et al, Chem. Mater. 2007
SDPSDP
Fiber optical spectrometer
Increasing rpm
accelerates nucleation ra
Temperature increase
L. Spanhel
Reactant 2
Moving position of the
flow cell
UV/Vis detector
HRS detector
Pump 2
Ti:Sa laser
IR Filter
Nd:YVO4
λ=800 nm, 80 MHz,
80 fs per pulse, 15nJ/pulse
Pump 1
Reactant 1
NP’s
Coupled linear UV-vis and non-linear optical (HRS) nanocolloid growth monitoring
Schürer, Segets, Peukert, 2010
University of Erlangen, Germany
Laser, ω
800 nm
SHG, 2ω
400 nm
Fiber optics
Hyper Rayleigh Scattering
L. Spanhel
P [C/m2] = Polarisation
χ(1) = F(n, er)
Input intensity
Output
χ(1)
χ(2)
χ(3)
linear optics
non-linear
optics
Linearity Non-linearity
n, e = cte
n, e ≠ cte
P = e0 (χ(1)Elin + χ(2)E2 + χ(3)E3 + …….)
fs - Laser :
E ~ 109 V/cm
(Sun: ~ 10 V/cm)
+
ind = a E
_ Ligands
permanent or
induced
oscillating dipoles
Essentials of non-linear optics
= el. susceptibility
n = refractive index
er= dielectric coefficient
L. Spanhel
In our case:
ZnO
ω 2ω
LiOH + Zn-precursor
UV
HRS
L. Spanhel
Isolation and total chemical analysis of monodispersed NP’s
Goal: quantification of atoms and molecules inside and in shells
ligand exchange and addition processes
tailoring for biomedicine (theranostics) and standardizations
T. Hyeon et al in
Nano Today 2014
L. Spanhel
sample nA (ns/nA)
100 [%]
A = 3/Rp
[m2/g]
Vm= M/
cm3/moL
SiO2 92 R3 82 1132 60,08 / 2,648
TiO2 99 R3 81,7 750 101,96 / 4,00
Al2O3 126 R3 78 709 79,86 / 4,23
ZnO 174 R3 74 535 81,4 / 5,6
Ag 245 R3 68 285 107,86 / 10,49
Pt 277 R3 67 139 195,08 / 21,45
Rp = 1 nm
Rp = radius
Mr = molar mass
p = density
A = spec. surface area
Vm = molar volume
“agglomeration number”
molecules per particle
p
Lrp
A
NMR
n


3
4 3

  3
2
As nn 
Characteristic parameters of spherical nanoparticles
Number of surface molecules
L. Spanhel
FFF Forced Field Fractionation
ppb-range!
L. Spanhel
FFF-ICP-MS
in comparison with
HRTEM and DLS
Note!:
FFF-ICP-MS : ~ µg/L
HRTEM-DLS : ~ mg/L
Ag
L. Spanhel
L. Spanhel
Inorganic nanostructures and Solartech
Introduction to renewable energy resources
Theory and applications of nanoscaled photocatalysts
Classical photovoltaics and future solar cells on the nanoscale
Chapter 2 solar sector
L. Spanhel
+
hn
Red
Ox
Heterogeneous
Photocatalysis
Photovoltaics
Electrochemistry
Analytics
Photochemistry
Photonics
Inorganic
chemistry
Materials
science
Catalysis Spin-offs
L. Spanhel
Energy resources of 21 century
decentralized
energy
CO2/H2 storage
CH4/CH3OH storage
Slunce
Nuclear power
light
heat
transport
Eolien
Soleil
Green synthetic chemistry
UV protection
Detox of ecosystems
Photovoltaics
Photocatalysis
Bio
Geothermie
Cosmic
neutrino field
L. Spanhel
History of solar technology
environmental
applications
Fujishima & Honda
1972
1980 20101839
A. Becquerel
Photoelectric
effect
membranes
preparative
org. synthesis
TiO2, ZnO, Fe2O3, CdS, ZnS, …
Chapin, Fuller, Pearson
PV 1. generation
mono-Si
nanotechnology
PV 2. generation
a-Si, CdTe,
CuInSe2
PV 3. generation
nanostructures
metamaterials
1954
H2O
H2 + O2
TiO2
O2
H2O2
ZnO
Veselovskii & Shub
1952
L. Spanhel
Semiconductor (SC) nanoelectrodes in solar sector
Photocatalysis
Open circuit
Solar cells
Closed circuit
+
Ox
Red
Red*
Ox*
+
Red*
Ox*
Charge
lumière lumière
L. Spanhel
Sun spectrum
E = hc/l
Space
Terre
Emission spectrum of our sun
L. Spanhel
Ox
Red
Ox
Red
2
16 







D

 p
R
e
kT
+
< 20 nm
Energy
VB
CB
+
0,1 - 1 µm
Ox
Red
2
12 







D


B
e
kT
B
D
Band bending
Space charge
SC - Electrochemistry: from micro to nano scale
L. Spanhel
+
Ox
light
Thermodynamics and kinetics of
semiconductor photocatalysis
1. Driving force of interfacial red ox processes
ECB,VB, E° (red ox)
2. Elementary processes in photoexcited nanoparticles:
diffusion, recombination, transfer, reaction
Red
L. Spanhel
E°SHE [ V ]
0
+1
+2
-2
-1
+3
-3
-4
0
1
2
3
4
E [ eV ]
Vacuum level, efree
Electrochemical
scale
Physics
scale
ZnS
3,7 eV CdS
2,4 eV
VB
CB
TiO2
3,2 eV
eA
Photoreduction:
EBC < E°(A/A-) !Eu2+/3+
Photooxidation:
EBV > E°(D/D+) !Co2+/3+
Note:
EBC = E° + 0,059 pHei
Quantum effects
Nanosize related shift
L. Spanhel
Kinetics and photocatalysis
h,e
p
D
D
R

 2
2


De,h ~ 10-5 m2/s:
Energy
BV
BC
+
A
<x2> = 2 D t
10 nm
D10nm = 10-9 m2/s
DA = 10-7 m2/s
1 fs
1 ps
1 ns
1 s
Recombination/Relaxation
of charge carriers
10
100
fluorescence
Brownian motion
log t
Life time of physical processes
governing the photocatalytical
performance
L. Spanhel
light
+
D = ?
Rp
he
p
D
D
R
,
2
2




D ~ 10-5 m2/s:
Rp: 5 nm D : 250 fs
20 nm 4 ps
énergie
BV
BC
+
trap
trap
r
t
r,t
t ~ D ~ nr
r,t > r > nr
Aad
A
L. Spanhel
Nanophotocatalyst optimization strategies
►spectral profile
visible light active nano’s are needed (400 – 600 nm)
►longe distance charge separation
heterostructures, dopings and surface modifications
► morphology of immobilized nanostructures
particle shapes, aggregate architectures and mesoporosity
►integration into photoreactor prototypes on various scales
nanocolloids, powders, thin coatings, photoreactor design
L. Spanhel
Note:
Avoid photo-corrosions
CdS, ZnS, Fe2O3
Photocatalysts of choice
L. Spanhel
Doping delivers better charge separation
relevant oxides: TiO2, ZnO, ZnTiO3
Energie
VB
CB
„charge transfer“
S0
S1
W6+, Fe3+,…
S2-, N3-
L
Cn+
An-
3 eV
2 eV
Ru, Rh, Pt-
complexes
L. Spanhel
Rapid separation of electron-hole pairs blocks
their thermal deactivation (nr, e-h recombination)
Energie
TiO2
+
VB
CB
+
Pd, Pt,..
TiO2
Anatas
Brookit
+ +
TiO2
CdS
L. Spanhel
Photocatalysis applications
1. Organic preparative synthesis
2. Environmental detoxification
3. Self-cleaning windows
4. Solar water splitting (solar fuels, hydrogen technology)
5. Carbon dioxide transformations
6. Biosystems in photocatalysis
ZnO/Fe3+
TiO2
ZnO
coatings
L. Spanhel
O2
O2
.-
OH-
H2O
.OH
+2.3 V
H+
+2H+
H2O2
+1.35 V
O.+2.7
V
Ti3+
-0.4 V
+
UV
TiO2
pH = 7
CxHyClz +
y - z
4
x + O2
hn
TiO2
xCO2 + zHCl +
y - z
4
H2O
Photomineralisation of organic pollutants
L. Spanhel
Solar decontamination of industrial waters in the VW
company in Taubate (Brasil) since 1999
Total surface: 50 m2
Turnover : 1 m3/jour
CATA: Hombikat-TiO2 (Anatase)
L. Spanhel
Florence Benoit, Toulouse
L. Spanhel
Super-Hydrophilicity
via photocatalysis
TiO2
Asahi
Pilkington
St. Gobain
PPG
L. Spanhel
UV
O2Ti
TiTi O2-
O2-
OH
Ti
O2-
OH
Ti
OH
Ti
O2-O2-O2Ti
TiTi
O2-
OH
Ti
O2-
OH
Ti
OH
Ti
O2-O2-O2-
Cavities
hydrophilichydrophobic
2O2- + 4h+ O2
Ti4+ + e- Ti3+
+H2O
- H+
Ti TiTi
O2-
OH
Ti
O2-
OH
Ti
OH
Ti
O2-O2-O2-
OHOHOH
super-hydrophilic
dark
Mechanistic view
of the formation of
Super-Hydrophilicity
L. Spanhel
Super-Hydrophilicity in the
car industry
Super-Hydrophilicity
in building constructions
Bacteria killing
Self-cleaning and sterilisation
of textiles
L. Spanhel
ZnxTiyOz Spinel-Nanostructures
Zn2TiO4 = Zn8
T(Zn8 Ti8)OO32
ZnTiO3 = Zn8
T(Zn8/3 Ti32/3 3)OO32
Zn2Ti3O8 = Zn8
T(Ti12 4)OO32
Fd3m
a = 840 - 844 pm
Ilmenite
h-ZnTiO3
ZnO6 TiO6
R3
a = 549 pm
Cubic inverse spinels
ZnO4
ZnO6
TiO6
Recall normal spinel:
AB2O4 = A8
TB16
OO32
L. Spanhel
Zn(Ac)2 2H2O
Ti(OBut)4
Synthesis of 2 M “polymeric” ZnxTiyOz Sols
EtOH
100°C
4 Zn(Ac)2·2(H2O) + [Zn4O](Ac)62 HAc + 7 H2O
Hydrolysis
Condensation
„Ti-O-Ti“
„Ti-O-Zn-O-Zn“
Z. Phys. Chem. 2007
G. Starukh et al.
Adv. Mater. 2006
F. Grasset et al.
Complexation
Esterification
L. Spanhel
20 30 40 50 60
XRD-intensity(a.u.)
2q (deg)
c- Zn2TiO4
c- ZnTiO3
h- ZnTiO3R-TiO2
Zn/Ti = 2
Zn/Ti = 2/3, 3/5
Zn/Ti = 1
Thermal growth of ZnxTiyOz nanocrystals
> 350°C
L. Spanhel
0
20
40
0,04
0,08
0,12
0,16
3000 2960 2920 2880 2840
Wave number (cm-1)
FTIRIntensity
h-ZnTiO3/r-TiO2 films in Photocatalysis
Photodegradation of Fetty Acids, Xe-lamp, air, rel. humidity: 80%
Norm.Integ.FTIR
Irrad. time, min
0 20 40 60 80 100 120
0
1
C22
C18
C10
C18
Phys. Chem. Chem. Phys. 2010
Krylova et al.
L. Spanhel
l (nm)
400 500 600 700
0,0
0,5
1,0
O.D.
„ZnTiON“
0’
80’
Methylene Blue photodegradation on “ZnTiON”-Spinel layers
(lex > 430 nm, Xe – Lamp, humid air)
Rel.ReflectanceIntensity
1600 1400 1200 1000
Wave number (cm-1)
Si - wafer
0 min
170 min
terminal
amines
conjugated
double bonds
„ZnTiON“ +MM
L. Spanhel
« Nanotechnology for hydrogen industries »
L. Spanhel
light
+
Hydrogen evolution
Oxygen evolution
nanophotocatalysts
Required photocatalytic efficiency: 10%
storage
H2
L. Spanhel
Hydrogen storage
In the car industry:
5-13 kg, ~ 500 km
1. Metal hydrides (chemisorption)
Mg + H2 (g) MgH2 DadH < 0
Capacity: 0,076 kg/kg (0,101 kg/L)
with nano-Pd
T , p
2. Physisorption on MOF
metal organic frameworks
[M4O](OOCR)6 M: Mg, Zn, Be
Capacity: 5-10 % w.
L. Spanhel
K. Maeda et al, Nature 2006
Best result on solar water splitting so far (f ~ 5%)
L. Spanhel
Other Photoreduction processes on combined SC-M hereterojunctions
MV2+
MV+.
alcohol
TiO2
CdS
Vis-light
M(OH)2
ketone
L. Spanhel
TiO2
AuCB
VB
CO2 photo-transformations
via surface plasmons
D. Astruc, Univ. Bordeaux
RSC-Chem. Soc. Rev. 2014, 43, 7188
540 nm LED
CO2
CH4
H2O
O2
L. Spanhel
D. Astruc, Univ. Bordeaux
RSC-Chem. Soc. Rev. 2014, 43, 7188
In most cases:
Yield > 50%
Selectivity > 90%
TiO2
AuCB
VB
540 nm LED
Pt,Pd
Cr6+
O2
CO2
H2O
●OH
Theory of Solar Cells of the 1. and 2. generation
Diode
hn
n p
anode cathode
n-Si/p-Si
n-GaAs/p-GaAs (InP)
n-CdS/p-CdTe
n-CdS/p-CuInSe2
el. contacts
Glass
Transparent conducting
electrode
Al@ZnO, F@SnO2
n-SC
p-SC
Graphite, Au, Mo, …
+
L. Spanhel
Pin = 1 kW / m2
η = conversion efficiency (0 - 1)
FF = fill factor
VOC = open circuit voltage (V)
ISC = short circuit current (A/m2)
Pin = solar input power (W/m2)
in
maxmax
in
scoc
P
IV
P
IV
FF 
Vmax
Imax
L. Spanhel
Polycrystalline Thin Film Cells
Cell Type
η (%)
Area
cm2
VOC
mV
JSC
mA/cm2
FF
%
Lab /
Company
Date
CdTe (cell) 3.5 mm
CSS
16 1.0 840 26.1 73.1 Matsushita 1997
CIGS submodule 14.2 51.7 6808 3.1 68.3 Showa Shell 1996
GaInP/GaAs
monolithic
30.3 4.0 2488 14.22 85.6 Japan Energy 1996
Si (large thin film) 16 95.8 589 35.6 76.3
Mitsubishi
(77µm on SiO2)
1997
a-Si (submodule)
non stabilised
12 100 1250 1.3 73.5 Sanyo 1992
in
maxmax
in
scoc
P
IV
P
IV
FF 
L. Spanhel
Origin of losses in
solar cells 1. Dissipation de la lumière limitée
2. Relaxation thermique
3. Perte lors de la séparation de charges
4. Contacts électriques non-idéales
5. Désactivation thermique (recombinaison)
losses
L. Spanhel
Cellules à base de Si
Mono-Si poly-Si amorphe Si
12-16% 11-13% 6-10%
L. Spanhel
soda lime
borosilicate
SnO2:FZnO:Al
80-300 nm, Eg=2,4 eV
1-8 m, Eg=1,5 eV
Au, Ti, Ag-graphite
CdTe module
Conversion efficiency > 21%
p-CdTe/n-CdS heterojunction
L. Spanhel
Solar Cells of the 3. generation
L. Spanhel
substrate
TCO- electrode Electron transfer region
Hole transfer region
catode
+
Nanostructured solar cells – 3. generation cells
e-
+
-
hn
solar nano-antenna design
Oxides, M-Chal., fulerenes, dyes
org. polymers
PPV, PEDOT-PSS
nano-
composites
anode
L. Spanhel
Same approach to nanostructured solar cell and photocatalysts
„Man-made“ micro-électrodes selon le principe de la nature
M
+
SC
+
SC1
SC2
+
SC
N
N
Ru
L. Spanhel
2. SC-polymère org.
4. Cellule de Grätzel
3. SC-SC1. Jonction SC-métal
Adopted from P. Kamat et al
ND National Lab, USA
L. Spanhel
1. Jonction SC-métal
eRendement
: 1 - 4%
Kamat et al,
Notre Dame National Lab
L. Spanhel
CdSe CdTe
Nanocomposites based on Q-CdSe, CdTe (antenna)
and organic Poly(3-hexylthiophene) (hole conductor)
eη
~ 5%
Alivisatos et al, Berkeley
L. Spanhel
3. SC-SC Rendement ~ 8 %
L. Spanhel
TiO2
Cellule de Grätzel (1988)
η ~ 10-12 %
L. Spanhel
Why and how actually is Grätzel cell functioning?
Organic dye antennas
Macrocrystal
TiO2
or
ZnO
Sol-gel derived membrane
10 microns thick
Nanocrystals: TiO2 or ZnO
O.A.%
< 1%
≈ 100%
!
1. Morphology !
L. Spanhel
10 m
300 nm
ZnO
TiO2
nanotubes
L. Spanhel
2. Antenna !
L. Spanhel
3. Cell kinetics ! 1 ps
1 ns
1 s
1 ms
10
100
réaction du chromophore
avec les ions d’iodure
transfert d’électrons
vers TiO2
recombinaison
interfaciale
Ligand
Ru2+/Ru3+
transfert d’électrons
à travers des agrégats de TiO2
I3
-
3I-
1
2
3
4
1
2
3
4
L. Spanhel
Construction d’une cellule d’après Grätzel
Degussa P 25 TiO2
Verre avec FTO Dye infiltration
Carbone electrode
Infiltration du KI3
Mesure
photoélectrique
L. Spanhel
L. Spanhel
L. Spanhel
L. Spanhel
L. Spanhel
E
L
LL
L
10:00 – 11:45, 14:00 – 16:00H