V. ArteroY. OudartA. FihriS. CanaguierA. Legoff

Hydrogen: Water, Sun and Catalysts

Marc FontecaveLaboratoire de Chimie et Biologie des Métaux, Université Joseph Fourier, CNRS, CEA/DSV/iRTSV

CEA-Grenoble 17 rue des martyrs 38054 Grenoble cedex 9, Francemfontecave@cea.fr; Phone: (0033)438789103 ; Fax: (0033)438789124

Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05

Doubling of the energetic supply in 40-50 years-World population increase(2050 from 6 to 9 billions)-economical growth

Limitation of the emission of green-house effect CO 2.

Limitation of the fossil sources of energy (petrol, gas, coal) coal: 200 years; gas: 100 years; oil: 50 years. Uranium: < 100 years, (surgenerators 300 years).

Need for new fuels from renewable sources

Energy global consumption(Total 13.5 TW)

Gas Hydro Renew

4.52

2.7 2.96

0.286

1.21

0.2860.828

0

1

2

3

4

5

TW

oil coal Biomass Nuclear

(U.S. 2004)

1-4¢ 2.3-5.0¢ 6-8¢ 5-7¢

Production cost of energy

6-7¢

25-50¢C

ost,

¢ /kW

-hr

0

5

10

15

20

25

coal Gas oil wind Nuclear Solar

Courtesy of Nate Lewis, Caltech

Storage

Potential of renewable energy sources

Hydro Tides &currents

wind Geotherm solar CurrentConsumption

0.1

1

10

100

1000

10000

100000

1000000

TW

SUN: The energy solution ! But how to store it ?

Solar energy:3x1024 joules/year

= 10000 x world populationsupply

(available for billions of years ) !!

Powering the planet with solar fuels

Water electrolysis

SUN: The energy solution ! But how to store it ?

H2

Electricity(batteries)

Water(bio)

photolysis

Solar energy:3x1024 joules/year

= 10000 x world populationsupply

(available for billions of years ) !!

Cracking

(Photo)fermentation

Photobioproduction

Biomass

Powering the planet with solar fuels

Electricity(storage:batteries)

>100000 TW/yr

13 TW/yr20 TW/yr (2030)25 TW/yr (2050) ?

Photovoltaics(reduce the cost 10-fold)

~160,000 km2 of photovoltaic panels can satisfy the énergetic demand in the US (3.3 TW)

SUN: The energy solution ! But how to store it ?

Powering the planet with solar fuels

Solar energy:3x1024 joules/year

= 10000 x world populationsupply

(available for billions of years ) !!

Photobioproduction

Biomass

>100000 TW/yr

100 TW/an

Biofuels

Solar energy:3x1024 joules/year

= 10000 x world populationsupply

(available for billions of years ) !!

13 TW/yr20 TW/yr (2030)25 TW/yr (2050) ?

THE IDEAL CYCLE

FUEL CELLS:Conversion of chemical energy

in electrical energy

2 H2 + O2 2 H2O∆∆∆∆H = - 570 kJ.mol -1

H2 2H+ + 2e-O2 + 4H+ + 4e- 2H2O

H2: 119930 kJ/kg; 33,3 kWh/kg(2.7 fold more than oil; 2.4 fold more than natural gas;5 fold more than coal).

Hydrogen: why ?

hydrogen

airwater

air

CH4 + H2O CO + 3 H2

∆∆∆∆H = + 165 kJ.mol -1

CO + H2O CO2 + H2

CH4 + 2 H2O CO2 + 4 H2800°C, 20 bars

Cata: Ni

Production of hydrogen : reforming

Production NH 3 (50%)

Chemicals (MeOH, H 2O2,..) (13%)

Refinery (37%)

Reforming factory (Air Liquide)

H2H2O

ELECTROLYSIS

HEAT

Renewable Energies(photovoltaics, wind,

hydraulic,…)

Biomass

THERMOCHEMICALTRANSFORMATION

GAZEIFICATION

PHOTOLYSIS

Biohydrogen: cyanobacteria, microalgea, hydrogenases, bioinspired catalysts

sun

Nuclear

soleil

Pt : an unsustainable metal500 millions of vehicles (av 75 kW) 0.4 g Pt/kW (2010); recycling 50%

Pt: stocks consumedwithin 15 years

Pt: an expensive metal

Pt: the best catalyst

Rh

Pt

Gordon et al. PNAS 2006Nature, 2007, 450,334

H2 production:The question of catalysis

Fd

PQ

PcH2O

Cytb6/f

H2ase

H+H2

NADPH

PS II PS I

FNRQA

O2

Rubisco

CO2

Amidon

Photosyntheticmicroorganisms

microalgaecyanobacteria

The catalysis solution ?« Biological » H2 photoproductionBioinspired

chemical systems

Mn

Ni, Fe

Production of H2: from sun and water ?

The « tough » part

- ∆G >>0- removal of 4 H+ and four e- from water- formation of an O-O bond- light collection and conversion

The « easy » part(somewhat tough)

- ∆G <0- combining 2 H+ and 2 e-

- formation of an H-H bondFrom W. Lubitz, En. Env. Sci. 2008

Biomimetic production of H2

Catalysts:

-Pt, Rh,…-Hydrogénases

- bioinspiredcomplexes

Source of electrons-Electricity (electrolysis)-Sacrificial reductant + hνννν

NiFe-[H2]ase from Allochromatium vinosumadsorbed on graphite shows a Nernstian behavior

as reversible as colloïdal platinumEisos = -400 mV/ENH

(30°C; pH 7; 0,1 bar H2)

Volbeda, A. et al., Nature (1995),373, 580-587.Volbeda, A. et al., J. Am. Chem. Soc. (1996), 118, 12989-12996.

Ni-Fe Hydrogenases and model compounds

2 H+ + 2 e- H2E = -400 mV vs SHE

(30°C; pH 7; 0,1 bar H 2)1500-9000 TON/s

Model compoundsStructural vs Functional

NiFe-[H2]ase adsorbed on graphite shows a Nernstian behavior

as reversible as colloïdal platinum

Darensbourg (1996) Pohl

Tatsumi (2005)

Bouwman*

Schröder

Sellmann

Darensbourg

Evans Schröder Schröder

Schröder Schröder

Canaguier et al., Dalton Trans., 2008

The biomimetic approach

No activity reported for dinuclear biomimetic nickel-i ron complexes

Towards Ni-Ru(CO) complexes….Why Ru?

Ru2+ accomodates both hard and soft ligands (H-, H2). Affinity for ππππ-acid ligands and H2

Ru2+ complexes activate H2(Noyori, Watanabe, Ogo, Rauchfuss,…)

Ligands: diimines, diphosphines,…

Electron-donorNiN2S2 or NiS4 ligands comparable to bipy (Darensbourg 2005)

Easy synthesis

SigolèneCanaguier

Towards Ni-Ru complexes ….

V. Artero, M. Fontecave et al Inorg. Chem. 2006, 45, 4334Eur. J. Inorg. Chem. 2007

[Ni(xbsms)]

[Ni(emi)]2-

H2emi: N,N’-ethylenebis(2-mercaptoisobutyramide)

H2xbsms: 1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene

Oudart et al. Inorg. Chem. 2006, Eur. J. Inorg. Chem. 2007S. Canaguier et al. Submitted 2009

Towards Ni-Ru complexes ….

24 turnovers in 4h at -1,6V vs Ag/AgCl

Electrocatalytic behavior:Cyclic Voltammetry (CV)

E /V vs Ag/AgCl-2 -1,5 -1 -0,5 0 0,5 1

Et3NH+

20 µA

DMF; 100 mV.s-1

Glassy carbon

Eher= - 1,44 V vs Ag/AgCl

H+H2

Electrocatalytic proton reduction

S. Canaguier, V. Artero, M. Fontecave, unpublished

Hg; DMF; 50 eq Et3NH+

100 % yieldStable after several runs

Bulk electrolysis: H2 productionControlled Potential Coulommetry (CPC

« HER potential » and « HER overvoltage »

Felton et al., Inorg. Chem., 2006, 45, 9181.

« HER overvoltage »

Biomimetic catalystsDMF

Increasing electrondensity decreases HER(CO force constant vs Eher)

0 -2-1

-0,78 (Pt:-0.95)Standard Potential

-1,60 -1,65

Eher(Et3NH+/H2)(V vs Ag/AgCl)

2 H+ + 2 e- H2E = -400 mV vs SHE (30°C; pH 7; 0,1 bar H 2)1500-9000 TON/s

H2O

- 1,44

E her /V vs Ag/AgCl

k CO

/ mdy

nes.

Å–1

15

15,5

16

16,5

17

-2,5 -2 -1,5 -1 -0,5

[NiFe] H2ase from D. gigas

E her /V vs Ag/AgCl

k CO

/ mdy

nes.

Å–1

15

15,5

16

16,5

17

-2,5 -2 -1,5 -1 -0,5

[NiFe] H2ase from D. gigas

Y. Oudart, V. Artero, J. Pécaut, C. Lebrun, M. Font ecave, Eur. J. Inorg. Chem., 2007

Ni-Ru complexes as functional modelsfor [Ni-Fe]hydrogenases

-Easy to synthesize

-Stable in solution

-High yields and high turnover numbersduring proton reduction to hydrogen

-High overvoltages (0.5-0.8 V)

Conclusion…

Abundance (ppm)

terrestrial crust oceans Price (€/g)

Pt 0,01 / 93 Ni 105 0,0005 0,194 Ru 0,01 / 15,7 Mn 1400 0,002 0,088 Fe 70 700 0,01 0,053

More biomimetic…Less expensive…

Unpublished results

230.009

20.0003

0.000058

Oudart et al. Inorg. Chem. 2006Eur. J. Inorg. Chem. 2007

Towards Ni-M complexes ….

Photo-productionof hydrogen

M. FONTECAVELaboratoire Chimie et Biologie des Métaux

UMR 5249-CEA/CNRS/UJFGrenoble - France

P.A. JacquesA. Fihri V. Artero

CO2

Pc

P680

Qa

P700

PSIIcytb6

NADPH

O2 + 4 H+

2 H2O

FNR

NADP+

cytf

Cycle de Calvin

[CHO]n

PSILHCLHC LHCLHCPQ(H)2

FdHydrogénase

2 H+H2

RuBP

Calvin cycle

hν

Sacrificial reducing agentOx

e-

M

H+

s

Catalyst

Photosensitizer

H2

Covalent bond

∆rG°= 476 kJ.mol -1

4 photons × 1.23 eV4 electrons involved

∆rG°= 140 kJ.mol -1

1 photon × 1.45 eV 2 electrons involved

1.56 eV ( 800 mn) < Visible radiation < 3.12 eV (400 nm)

Photobiohydrogen and model reaction

N

N

N

N

N

N

Ru

2+

Me-

e-

½ H2

Find the good catalystM

Find the good photosensitizer

Make a multi-functional (supramolecular) system

N

N

N

NN

NRu M

Linker: tunes the electronic communicationbetween the two components

CatalystLight-harvesting

center

Make this reaction useful (sacrificial electron donor: H2O)

H+

NP

PN NiP

P

N

Cy

CyCy

Cy

N

bz

bz bz

bz

Dubois et al. J. Am. Chem. Soc., 2006.

Eher = -0.4V vs Ag/AgCl

Cobaloximes as functional models for hydrogenases. 2. Proton electroreduction catalyzed by difluoroboryl-bis(dimethylglyoximato)-cobalt(II) complexes in organic mediaC. Baffert, V. Artero, M. FontecaveInorg. Chem.. 2007, 46, 1817-1824

Eher = - 0.4 V vs Ag/AgCl in CH3CN92 TON.h-1 (- 0.5 V)pKa= 7,6

NC NH3+NC NH3+

CF3SO3HpKa= 2.6

One of the rare catalyst for H2 oxidationE =-0.27 vs Ag/AgCl

H2/Et3N

Best catalysts:overvoltage, TOF,..

+Acetone

3h, T.A

CoIICoI

DMF 0.1M n-Bu4NBF4 assupporting electrolyte glassy carbon electrode, v = 100 mV.s-1

5µA

-2 -1.5 -1 -0.5 0 0.5 1

E /V vs Ag/AgCl

N

N

N

NN

NRu M A Ru-Co complex

0

10

20

30

40

50

60

0 1 2 3 4irradiation time /h

TO

N

0

10

20

30

40

50

60

DM

F

CH

3CN

CH

3OH

Acetone

1,2

-dic

hlo

roét

han

e

H2 : GC analysis

acetone

CH3CN

H+

½ H2

Et3N

Et3N•+

H2 Photoproduction

Fihri, A.; Artero, V.; Razavet, M.; Baffert, C.; Leibl, W.; Fontecave, M., Cobaloxime-Based Photocatalytic devices for Hydrogen Production.Angewandte Chemie, International Edition 2008

Hg lamp (> 350 nm)AcetoneEt3N : 100 equiv.Et3NHBF4 : 100 equiv

0

20

40

60

80

100

120

140 TON

E°(Co II/CoI) = -0.9 V vs Ag/AgCl

E°(Co II/CoI) = -0.41 V vs Ag/AgCl

A tunable supramolecular system:1. the coordination sphere

E°(CoII/CoI) = -0.23 V vs Ag/AgCl

+ exces dmgH2 17 TON

+

2 TON

56 TON 120 TON

Fihri, Artero, Leibl, Fontecave, Angew. Chem. 2008

A tunable supramolecular complex2. the linker

210 2739

> 380 nmFihri, Artero, Fontecave, Dalton Trans 2008

Turnovers

A tunable supramolecular complex3. the photosensitizer

Sakai et al.J. Am. Chem. Soc.

2006.

Aqueous acetate bufferEDTA pH 5TON = 4.8

Vos et al.Angew. Chem. Int. Ed.

2006.

CH3CNEt3NTON = 56

CH3CN/H2ODimethylanilineTON = 60

Brewer et al.J Am. Chem. Soc.

2007

acetoneEt3NTON = 120

Artero, Fontecave et al.Angew. Chem. Int. Ed.

2008.

Aqueous bufferascorbateTON = 20

M’

[Ru(µµµµ-OAc)(bpp)(terpy)2]Angew chem 2008, 47, 5830

TN: 250Llobet

The « Graal » : H2O as the source of electrons

2760Bernhard

JACS 2007100-600

ThummelInorg. Chem. 2008

500Bonchio, HillAngew. 2008

1000Dismukes

Angew. 2008

Ce(IV)électrode

Co(PO4)Nocera

Science 2008

Project GRAFTHYDRO

Bio-inspired nanomaterials for Hydrogen evolution: towards alternatives to platinum nanoparticles

Laboratoire de Chimie et Biologie des métauxUMR 5249 CEA/CNRS Université Jospeh Fourier

Laboratoire de Chimie des Surfaces et InterfacesCEA Saclay

H2

Marc FontecaveVincent Artero

Alan Legoff

Serge PalacinBruno Jousselme

e-

Photoelectrochemical cell: water photoelectrolysis

H+

H+

H2

O2

H2O

H+

Photoanode

SC-n : Fe2O3/WO3

Cathode

or

Photocathode

H+

O2 H2

2H2O = O2 + 2H2

NP

PN NiP

P

N

Cy

CyCy

Cy

N

bz

bz bz

bz

Dubois et al. J. Am. Chem. Soc., 2006.

Eher = -0.4V vs Ag/AgCl

Cobaloximes as functional models for hydrogenases. 2. Proton electroreduction catalyzed by difluoroboryl-bis(dimethylglyoximato)-cobalt(II) complexes in organic mediaC. Baffert, V. Artero, M. FontecaveInorg. Chem.. 2007, 46, 1817-1824

Eher = - 0.4 V vs Ag/AgCl in CH3CN92 TON.h-1 (- 0.5 V)pKa= 7,6

NC NH3+NC NH3+

CF3SO3HpKa= 2.6

One of the rare catalysts for H2 oxidationE =-0.27 vs Ag/AgCl

H2/Et3N

Best catalysts:overvoltage, TOF,..

Hydrogenases

Bio-inspired catalystsElectrocatalytic activity demonstrated in solution

What about the electrocatalytic activity of the complexes grafted on the electrodes ???

Bio-inspired nanomaterials for Hydrogen evolution

European patent application EP-08 290 988.8 NOVEL MATERIALS AND THEIR USE FOR THE ELECTROCATALYTIC EVOLUTION OR UPTAKE OF H2

Dubois et al., J. Am. Chem. Soc. 2007,128, 358

N 1s

395400405

Binding energy (eV)

200 Counts/s

RNH2399.9

RNH3+

401.6

MWNTs

ITO

MWNTs electrode functionalizationwith metal catalysts

850860870880890

Binding Energy (eV)

500 Counts/s

2p1/2873.9

2p3/2

856.0Ni

850860870880890

Binding Energy (eV)

500 Counts/s

2p1/2873.9

2p3/2

856.0

850860870880890

Binding Energy (eV)

500 Counts/s

2p1/2873.9

2p3/2

856.0Ni

2p132.2

P

130135

X-ray Photoelectron Spectroscopy (XPS)

- 0.2 V

(Eher= -0.3 V vs Ag/AgCl)

n = 1.5 10-9 mol.cm-2 Scanning Electron Microscopy (SEM)

e-

H+

H2[D

MF

-H]+

-0,8 -0,6 -0,4 -0,2 0,0 0,2

E /V vs Ag/AgCl

2OOµA

European patent application EP-08 290 988.8

CH3CN

Electrocatalytic properties of the modified electrodes

>20.000 turnovers within 1h !! (6 s -1)94% faradaic yieldNo evidence for loss of activity over hours

Controlled potential coulometry(-0.5 V vs Ag/AgCl)CH3CN /[DMFH](OTf) 60 mMGC analysis of H2

n = 1.5 10-9 mol.cm-2

Ni-ITO-MWCNT

DMFH+: pKa=6.1 in CH3CNE°= - 0.1 V vs Ag/AgCl

-0.3 V(overvoltage: 0.2V)

Activity in water !! (N. Guillet, LITEN, CEA)

Ring (Pt)- Disk(vitreous C + Nafion + Ni-NTC) configurationH2SO4 0.1 MRotating-disk electrode measurements

H2 evolution with 18 mV overvoltage

Membrane (Nafion)- Gas Diffusion Layer (Ni-NTC) half-cellH2SO4 0.1 M

A material compatiblewith PEM technology(Nafion membrane,Acidic conditions)

V. ArteroY. OudartA. FihriS. CanaguierA. Legoff

Hydrogen: Water, Sun and CatalystsMarc Fontecave

Laboratoire de Chimie et Biologie des Métaux, Université Joseph Fourier, CNRS, CEA/DSV/iRTSVCEA-Grenoble 17 rue des martyrs 38054 Grenoble cedex 9, France

mfontecave@cea.fr; Phone: (0033)438789103 ; Fax: (0033)438789124

Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05