2269-9

Workshop on New Materials for Renewable Energy

Paolo FORNASIERO

17 - 21 October 2011

Dept. of Chemcial Sciences University of Trieste

Italy

Photocatalytic H2 and added-value byproducts: The role of metal oxide systems in their synthesis from liquid oxygenates

Photocatalytic H2 and added-value byproducts: the role of metal oxide systems in their synthesis from liquid oxygenates

Workshop on New Materials for Renewable EnergyTrieste 17-10-2011

Paolo Fornasiero

University of Trieste

(a)

(b)

100 nm

100 nm Si(100)

100 nm

Si(100)

1 μm

(a)

(b)

(a)

(b)

100 nm100 nm100 nm

100 nm100 nm Si(100)Si(100)

100 nm100 nm

Si(100)Si(100)

1 μm

OutlineOutline

1. Introduction: motivation and context

2. Nanostructured powder materials

- CuOx@TiO2

- CuOx or Pd on B,N co-doped TiO2

- Pt, Au and Pt-Au on TiO2

3. Supported nanoarchitectures

- CuO and Cu2O

- Bare and Au doped CuOx/TiO2

- Bare and F- doped Co3O4

- Ag/ZnO

4. Perspectives

85%

4% 4% 7%

50%37%

8% 5%

Current world production ~ 500 billion Nm3/yr

MotivationMotivation ofof HH22 production production

Currently, most of the CO2 associated with H2

production is released toatmosphere

PRODUCTIONPRODUCTION

CONSUMPTIONCONSUMPTION

Photoinduced reaction Photon energy conversion reactionDegradation

ΔG<0 (down hill)

Organic compounds+ O2

CO2 + H2O + etc

Water splitting

Pot

entia

l

ΔG>0 (up-hill)

H2 + O2

H2OPot

entia

l

Hydrogen production strategies and photoHydrogen production strategies and photo--catalysiscatalysisSteam reforming (methane, oxygenates ….)

Partial oxidation reaction (methane, oxygenates …)Auto-thermal reforming (methane, oxygenates …)

Aqueous phase reforming (oxygenates,…)Electrolysis by renewable energyGasification (biomass….)Bacteria (biomass…)Thermo-chemical water splittingPhoto-catalytic reforming of oxygenatePhoto-catalytic water splitting

Sustainability

PhotocatalyticPhotocatalytic HH22 production production

Fujishima A, Honda K (1972) Nature 238:37Renewable and Sustainable Energy Reviews 11 (2007) 401-425Topics in Catalysis 49 (2008) 4-17

PhotocatalyticPhotocatalytic HH22 production production

Fujishima A, Honda K (1972) Nature 238:37Renewable and Sustainable Energy Reviews 11 (2007) 401-425Topics in Catalysis 49 (2008) 4-17

PhotoreformingPhotoreforming

Photon energy conversion reaction

Photoreforming

ΔG>0 (up-hill)

(2x + y/2 – z) H2+ x CO2

CxHyOz + (2x-z) H2O

Pot

entia

l

Photon energy conversion reaction

Photoreforming

ΔG>0 (up-hill)

(2x + y/2 – z) H2+ x CO2

CxHyOz + (2x-z) H2O

CxHyOz + (2x - z) H2O → x CO2 + (2x + y/2 – z) H2

OutlineOutline

1. Introduction: motivation and context

2. Nanostructured powder materials

- CuOx@TiO2

- CuOx or Pd on B,N co-doped TiO2

- Pt, Au and Pt-Au on TiO2

3. Supported nanoarchitectures

- CuO and Cu2O

- Bare and Au doped CuOx/TiO2

- Bare and F- doped Co3O4

- Ag/ZnO

4. Perspectives

Fundamental conditions: largely available, low cost, non toxic,…

i) M act as electron collector

ii) Photodeposition of M

The Fermi level of the metal is lower thanthat of TiO2

Redox potential of Mn+/M > energy edgeof the conduction band

Selection of the metalSelection of the metal

Encapsulation of preformed metal nanoparticles into porous MOx throughdifferent methodologies.

P. Fornasiero et al., ChemSusChem 3 (2010), 24-42

PhotoreformingPhotoreforming: the CuO: the CuOxx@TiO@TiO2 systemsystem

P. Fornasiero et al., The Journal of Physical Chemistry C 113 (2009), 18069-18074

1. Nanoparticles formation:

Microemulsion Metal nanoparticle

Surfactant

Triton X-100

Cu(NO3)2

hydrazineColloidal Cu dispersion

Synthesis: embedding approachSynthesis: embedding approach

P. Fornasiero et al. Nanoscience and Nanotechnology Letters 1 (2009), 128-133

2. Precipitation of Ti(OH)4

The colloidal Cu dispersion was added to Ti(i-PrO)4 in cyclohexane

Aging, filtration and washing

3. Drying and calcination

Copper oxide nanoparticle

TiO2 matrix

Cu(x%)@TiO2

Calcination 450 °C

1. Microemulsion method

Ti(i-PrO)4Triton X-100in cyclohexane

H2O / hydrazine

Precipitationand

Aging r.t.

RecoveryWashing

DryingCalcination 450°C

TiO2

SynthesisSynthesis: : CuOCuOxx ––TiOTiO22

2. Impregnation method

TiO2 + Cu(NO3)2 in EtOH

Stirred 2 h in the dark, dried and calcined 1 h at 450 °C

IMP Cu(x%)/TiO2

P. Fornasiero et al., Nanoscience and Nanotechnology Letters 1 (2009), 128-133

BasicBasic characterizationcharacterization ofof CuOCuOxx@TiO@TiO2 system vs system vs CuOCuOx ––TiOTiO2 system

P. Fornasiero et al., Nanoscience and Nanotechnology Letters 1 (2009), 128-133

Composition (%)

BET Surface area (m2g)

Anatase Rutile Brookite

IMP Cu(2.5%)/TiO2 64 92 3 5

Cu(2.5)@TiO2 69 91 6 3

Sample Shell N R (nm) DM (nm)

Cu(2.5%)@TiO2fresh

Cu-OCu-Cu

3.8-

0.1962- -

Cu(2.5%)@TiO2irradiated

Cu-OCu-Cu

4.02.2

0.19750.2572 0.8

Sample Shell N R (nm) DM (nm)

Cu(2.5%)/TiO2Fresh

Cu-OCu-Cu

3.5-

0.1989- -

Cu(2.5%)/TiO2Irradiated

Cu-OCu-Cu

3.1-

0.1959- -

Cu@TiO2

Cu/TiO2

• Cu(II) in the fresh samples

• Partial reduction of Cu after irradiation

• Very small Cu particles

• Very small amount of reduced Cu after irradiation.

XAFS XAFS CharacterizationCharacterization

P. Fornasiero et al., J. Phys. Chem. A, 2010, 114 (11) 3916–3925

HAADFHAADF--STEM STEM CharacterizationCharacterization

5 nm

Particle Size (nm)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Perc

enta

ge o

f Au

Part

icle

s

0

5

10

15

20

25

30

35%

ofC

u Pa

rticl

es

Cu@TiO2

Cu@TiO2

Cu/TiO2

P. Fornasiero et al., J. Phys. Chem. A, 2010, 114 (11) 3916–3925

Cu/TiO2

PhotocatalyticPhotocatalytic hydrogen productionhydrogen productionPHOTOCATALYTIC ACTIVITY 2.5% CuPHOTOCATALYTIC ACTIVITY 2.5% Cu--TiOTiO22 traditionaltraditional vsvs advancedadvanced

Traditional

P. Fornasiero et al., The Journal of Physical Chemistry A 114 (2010), 3916-3925

0

200

400

600

800

1000

1200

0 1 2 3 4 5 6

ethanol

0

200

400

600

800

1000

1200

0 1 2 3 4 5 6

methanol

0

200

400

600

800

1000

1200

0 1 2 3 4 5 6

glycerol

H2

evol

utio

nra

te /

μ mol

ih-1

Irradiation time / h

Advanced

CATALYTIC ACTIVITY: HCATALYTIC ACTIVITY: H22 PRODUCTION FROM PRODUCTION FROM ETHANOLETHANOL

Possible pathway

Acetaldehyde diethoxy acetalaccumulates in solution

P. Fornasiero et al., ChemCatChem 3 (2011), 574-577

CATALYTIC ACTIVITY: HCATALYTIC ACTIVITY: H22 PRODUCTION FROM PRODUCTION FROM GLYCEROLGLYCEROL

Possible pathway Accumulatedin solution

P. Fornasiero et al., ChemCatChem 3 (2011), 574-577

1,3-dihydroxypropanone

hydroxyacetaldehyde

IsopropanolIsopropanol and and glucoseglucose photoreformingphotoreforming

P. Fornasiero et al., European Journal of Inorganic Chemistry 2011 (2011), 4309-4323

0.368 mM glycerol

D. I. Kondarides, V. M. Daskalaki, A. Patsoura, X. E. Verykios, Catalysis Letters 2008, 122, 26-32

PtPt--TiOTiO22 photophoto--catalystscatalysts : : stabilitystability under under glycerolglycerolphotoreformingphotoreforming

0

200

400

600

800

1000

0 200 400 600 800

time / min

H2

evol

utio

n ra

te /

μm

oli m

in-1

50% water – 50% ethanol

PhotocatalyticPhotocatalytic stabilitystability: 2.5% CuO: 2.5% CuOxx@TiO@TiO22

CH3CH2OH + 3H2O 6H2 + 2CO2hν, cat

LEACHING CuLEACHING Cu

P. Fornasiero et al., The Journal of Physical Chemistry A 114 (2010), 3916-3925

0

5

10

15

20

25

30

0 10 20 30 40 50Time / h

% le

achi

ng C

u

under UV vis irradiation

Cu@TiO2

Cu/TiO2

VisibleVisible light light drivendriven photocatalystphotocatalyst: Pd or : Pd or CuOCuOxx on on

B, N B, N coco--dopeddoped TiOTiO22

0.0

0.2

0.4

0.6

0.8

1.0

0 60 120 180 240Irradiation time (min)

C/C 0

TiO2

TiO2-B9

TiO2-N5

TiO2-B9-N5

P25 Degussa

0.0

0.2

0.4

0.6

0.8

1.0

0 60 120 180 240Irradiation time (min)

C/C 0

TiO2

TiO2-B9

TiO2-N5

TiO2-B9-N5

P25 Degussa

Dyes Degradation

P. Fornasiero, Chem. Phys. 339 (2007) 111-123.

SynthesisSynthesis ofof the the catalystcatalyst

Metal photodepositionPd(0.5%)/TiO2

Pd(0.5%)/TiO2-B,NCu(1.0%)/TiO2

Cu(1.0%)/TiO2-B,N

Support +metal nitrate

50% water- 50% methanol

UV-vis irradiation

Cu(1.0%)/TiO2

HAADF-STEM

Highly dispersed metal nanoparticles

Deposition as M0 (XANES-EXAFS)

Texture and phase compositionare not affected

P. Fornasiero, ChemCatChem 3 (2011), 574-577

CATALYTIC ACTIVITY: ORIGIN OF Vis ACTIVITYCATALYTIC ACTIVITY: ORIGIN OF Vis ACTIVITY

UV irradiation

Vis irradiation

As proposed for Au/TiO2A. Primo, A. Corma and H. Garcia, Phys. Chem. Chem. Phys. 13 (2011), 886-910.

EnhanchedEnhanched photocatalyticphotocatalytic activityactivity ofof hydrogenatedhydrogenated blackblackTiOTiO22

Xiaobo Chen, et al., Science 331, 746 (2011)

OutlineOutline

1. Introduction: motivation and context

2. Nanostructure powder materials

- CuOx@TiO2

- CuOx or Pd on B,N co-doped TiO2

- Pt, Au and Pt-Au on TiO2

3. Supported nanoarchitectures

- CuO and Cu2O

- Bare and Au doped CuOx/TiO2

- Bare and F- doped Co3O4

- Ag/ZnO

4. Perspectives

DevelopmentDevelopment ofof supportedsupported CuOCuOxx photophoto--catalystscatalysts

P. Fornasiero et al., ChemSusChem 2 (2009), 230-233.

Cu nanustructure and H2 photo-production from methanol water solution

100 nm (a) (b)1 μm

Si(100)Si(100)

100 nm (a) (b)1 μm

Si(100)Si(100)

CuOCu2O

Cu2O

CuO

Bare and Au Bare and Au dopeddoped CuOCuOxx/TiO/TiO22 photophoto--catalystscatalysts

P. Fornasiero et al. ,Advanced Functional Materials 21 (2011), 2611-2623

VIS UV

Activity vs stability

Oxygen assisted HOxygen assisted H22 production over Coproduction over Co3OO4photocatalystsphotocatalysts

Oxygen free Oxygen assisted

P. Fornasiero et al., Chem. Vap. Deposition 2010, 16, 296

Ag/Ag/ZnOZnO nanocompositenanocomposite photocatalystsphotocatalysts

(c)

(a)

(b)

(d)

(e)

(f)

(g)

P. Fornasiero et al., International Journal of Hydrogen Energy (2011), in press, doi:10.1016/j.ijhydene.2011.09.045

(b)

0 4 8 12 16 20 24 280

1

2

3

4

5

30 min90 min

Time (h)

H2

evol

utio

n(μ

mol

×h-1×c

m-2

)

HH2O/CHO/CH3OH solutionsOH solutions

PerspectivesPerspectives

Photocatalytic reforming of renewable oxygenates to produce hydrogen is an attractive research topic.

In order to transform it into a technological process, we must:

- Increase photocatalytic efficiency- Increase activity under visible light irradiation- Increase stability- Explore its potential use in water-water treatments- Explore simultaneous hydrogen production and

valorisation of the partially oxidized byproducts

ACKNOWLEDGEMENTSACKNOWLEDGEMENTS

Prof. Mauro Graziani, Prof. Paolo Fornasiero, Dr. Valentina Gombac, Dr. Matteo Cargnello, Dr. Nicolàs M. BerteroOur web site: www.dsch.units.it/~fornasiero/index.htm

Prof. Mauro Graziani, Prof. Paolo Fornasiero, Dr. Valentina Gombac, Dr. Matteo Cargnello, Dr. Nicolàs M. BerteroOur web site: www.dsch.units.it/~fornasiero/index.htm

• University of Trieste• INSTM Consortium• ICCOM-CNR• Fondazione CRTrieste• Fondo Regione FVG

ThankThank youyou forfor youryour attentionattention

Dr. D. Barreca, Dr. A. Gasparotto, Prof. E. Tondello University of Padova and CNRDr. V. Dal Santo, Dr. R. Psaro, CNR - Milano