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Hydrogen: Water, Sun and Catalysts Marc Fontecave Laboratoire de Chimie et Biologie des Métaux, Université Joseph Fourier, CNRS, CEA/DSV/iRTSV CEA-Grenoble 17 rue des martyrs 38054 Grenoble cedex 9, France [email protected]; Phone: (0033)438789103 ; Fax: (0033)438789124 Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05 V. Artero Y. Oudart A. Fihri S. Canaguier A. Legoff Need for new fuels from renewable sources 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 CO2. 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). Energy global consumption (Total 13.5 TW) 5 4.52 4 2.7 3 2.96 TW 2 1.21 0.828 1 0.286 0.286 0 oil Gas coal Hydro Biomass Renew Nuclear Production cost of energy (U.S. 2004) 25-50¢ Cost, ¢/kW-hr 25 20 Storage 15 10 1-4¢ 2.3-5.0¢ 6-8¢ 5-7¢ 6-7¢ 5 0 coal Gas Courtesy of Nate Lewis, Caltech oil wind Nuclear Solar Potential of renewable energy sources TW 1000000 100000 10000 1000 100 10 1 0.1 Hydro Tides & currents wind Geotherm solar Current Consumption Powering the planet with solar fuels SUN: The energy solution ! But how to store it ? Solar energy: 3x1024 joules/year = 10000 x world population supply (available for billions of years ) !! Powering the planet with solar fuels SUN: The energy solution ! But how to store it ? Electricity (batteries) Solar energy: 3x1024 joules/year Photo bioproduction Water (bio) photolysis Water electrolysis Cracking Biomass (Photo) fermentation H2 = 10000 x world population supply (available for billions of years ) !! Powering the planet with solar fuels SUN: The energy solution ! But how to store it ? Photovoltaics >100000 TW/yr (reduce the cost 10-fold) Electricity (storage: batteries) Solar energy: 3x1024 joules/year = 10000 x world population supply (available for billions of years ) !! 13 TW/yr 20 TW/yr (2030) 25 TW/yr (2050) ? ~160,000 km2 of photovoltaic panels can satisfy the énergetic demand in the US (3.3 TW) >100000 TW/yr Solar energy: 3x1024 joules/year = 10000 x world population supply (available for billions of years ) !! Photo bioproduction Biofuels Biomass 100 TW/an 13 TW/yr 20 TW/yr (2030) 25 TW/yr (2050) ? THE IDEAL CYCLE Hydrogen: why ? hydrogen air FUEL CELLS: Conversion of chemical energy in electrical energy H2 air water 2H+ + 2e- 2 H2 + O2 O2 + 4H+ + 4e- 2 H2O ∆H = - 570 kJ.mol-1 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). 2H2O Production of hydrogen : reforming CH4 + H2O CO + 3 H2 CO + H2O CO2 + H2 CH4 + 2 H2O CO2 + 4 H2 800°C, 20 bars Cata: Ni ∆H = + 165 kJ.mol-1 Production NH3 (50%) Reforming factory (Air Liquide) Chemicals (MeOH, H2O2,..) (13%) Refinery (37%) Renewable Energies soleil (photovoltaics, wind, hydraulic,…) ELECTROLYSIS Biomass Nuclear H2 H2O THERMOCHEMICAL TRANSFORMATION GAZEIFICATION HEAT PHOTOLYSIS sun Biohydrogen: cyanobacteria, microalgea, hydrogenases, bioinspired catalysts H2 production: The question of catalysis Pt: the best catalyst Pt: an expensive metal Pt : an unsustainable metal Rh 500 millions of vehicles (av 75 kW) 0.4 g Pt/kW (2010); recycling 50% Pt: stocks consumed within 15 years Gordon et al. PNAS 2006 Nature, 2007, 450,334 Pt Bioinspired chemical systems The catalysis solution ? « Biological » H2 photoproduction Photosynthetic microorganisms CO2 microalgae cyanobacteria Rubisco H+ H 2 H2ase Amidon NADPH FNR QA PQ PS II H2O Mn Fd Cyt b6/f Pc O2 Ni, Fe PS I Production of H2: from sun and water ? The « tough » part The « easy » part (somewhat tough) - ∆G >>0 - removal of 4 H+ and four e- from water - ∆G <0 - formation of an O-O bond - combining 2 H+ and 2 e- light collection and conversion - formation of an H-H bond From W. Lubitz, En. Env. Sci. 2008 Source of electrons -Electricity (electrolysis) -Sacrificial reductant + hν ν Biomimetic production of H2 Catalysts: -Pt, Rh,… -Hydrogénases NiFe-[H2]ase from Allochromatium vinosum adsorbed on graphite shows a Nernstian behavior as reversible as colloïdal platinum Eisos = -400 mV/ENH (30°C; pH 7; 0,1 bar H2) - bioinspired complexes Ni-Fe Hydrogenases and model compounds NiFe-[H2]ase adsorbed on graphite shows a Nernstian behavior as reversible as colloïdal platinum Volbeda, A. et al., Nature (1995), 373, 580-587. Volbeda, A. et al., J. Am. Chem. Soc. (1996), 118, 12989-12996. Model compounds Structural vs Functional 2 H+ +2 e- H2 E = -400 mV vs SHE (30°C; pH 7; 0,1 bar H 2) 1500-9000 TON/s The biomimetic approach Canaguier et al., Dalton Trans., 2008 Darensbourg (1996) Pohl Darensbourg Evans Schröder Schröder Schröder Sellmann Tatsumi (2005) Schröder Schröder Bouwman* No activity reported for dinuclear biomimetic nickel-iron complexes Towards Ni-Ru(CO) complexes…. Why Ru? Sigolène Canaguier Ru2+ accomodates both hard and soft ligands (H-, H2). Affinity for π-acid ligands and H2 Ru2+ complexes activate H2 (Noyori, Watanabe, Ogo, Rauchfuss,…) Ligands: diimines, diphosphines,… Electron-donor NiN2S2 or NiS4 ligands comparable to bipy (Darensbourg 2005) Easy synthesis Towards Ni-Ru complexes …. [Ni(emi)]2- H2emi: N,N’-ethylenebis (2-mercaptoisobutyramide) [Ni(xbsms)] H2xbsms: 1,2-bis(4-mercapto-3,3dimethyl-2-thiabutyl)benzene V. Artero, M. Fontecave et al Inorg. Chem. 2006, 45, 4334 Eur. J. Inorg. Chem. 2007 Towards Ni-Ru complexes …. Oudart et al. Inorg. Chem. 2006, Eur. J. Inorg. Chem. 2007 S. Canaguier et al. Submitted 2009 Electrocatalytic proton reduction Electrocatalytic behavior: Cyclic Voltammetry (CV) E /V vs Ag/AgCl -2 -1,5 -1 Et3NH+ -0,5 0 0,5 1 Bulk electrolysis: H2 production Controlled Potential Coulommetry (CPC 20 µA DMF; 100 mV.s-1 Glassy carbon H2 H+ Eher= - 1,44 V vs Ag/AgCl 24 turnovers in 4h at -1,6V vs Ag/AgCl S. Canaguier, V. Artero, M. Fontecave, unpublished Hg; DMF; 50 eq Et3NH+ 100 % yield Stable after several runs « HER potential » and « HER overvoltage » E = -400 mV vs SHE (30°C; pH 7; 0,1 bar H 2) 1500-9000 TON/s H2 2 H+ + 2 e - H2O DMF Standard Potential -0,78 (Pt:-0.95) Eher(Et3NH+/H2) (V vs Ag/AgCl) 0 Biomimetic catalysts - 1,44 -1,60 -1,65 -2 -1 « HER overvoltage » 17 (CO force constant vs Eher) 16,5 kCO / mdynes.Å–1 Increasing electron density decreases HER 16 15,5 Felton et al., Inorg. Chem., 2006, 45, 9181. Y. Oudart, V. Artero, J. Pécaut, C. Lebrun, M. Fontecave, Eur. J. Inorg. Chem., 2007 [NiFe] H2ase from D. gigas 15 -2,5 -2 -1,5 E her /V vs Ag/AgCl -1 -0,5 Conclusion… Ni-Ru complexes as functional models for [Ni-Fe]hydrogenases -Easy to synthesize -Stable in solution -High yields and high turnover numbers during proton reduction to hydrogen -High overvoltages (0.5-0.8 V) More biomimetic…Less expensive… Unpublished results Abundance (ppm) Pt Ni Ru Mn Fe terrestrial crust oceans 0,01 105 0,01 1400 70 700 / 0,0005 / 0,002 0,01 Price (€/g) 93 23 0,194 0.009 15,7 2 0.0003 0,088 0.000058 0,053 Towards Ni-M complexes …. Oudart et al. Inorg. Chem. 2006 Eur. J. Inorg. Chem. 2007 Photo-production of hydrogen M. FONTECAVE Laboratoire Chimie et Biologie des Métaux UMR 5249-CEA/CNRS/UJF Grenoble - France P.A. Jacques V. Artero A. Fihri Photobiohydrogen and model reaction RuBP H2 CO2 H+ [CHO]n Cycle decycle Calvin Calvin H2 2 H+ + Hydrogénase NADP NADPH Fd FNR Qa LHC 2 H2O PSII P680 PQ(H)2 O2 + 4 cytb6 Catalyst M hν e- Covalent bond s Photosensitizer PSI LHC P700 cytf Pc Sacrificial reducing agent H+ ∆rG°= 476 kJ.mol -1 4 photons × 1.23 eV 4 electrons involved Ox ∆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) 2+ N N N Ru e- N N e½ H2 N M H+ Find the good catalyst M Find the good photosensitizer Make a multi-functional (supramolecular) system Make this reaction useful (sacrificial electron donor: H2O) Light-harvesting center N N N Ru N N M Catalyst N Linker: tunes the electronic communication between the two components Best catalysts: overvoltage, TOF,.. NH3+ NC pKa= 7,6 Eher = - 0.4 V vs Ag/AgCl in CH3CN 92 TON.h-1 (- 0.5 V) Cobaloximes as functional models for hydrogenases. 2. Proton electroreduction catalyzed by difluoroboryl-bis(dimethylglyoximato)-cobalt(II) complexes in organic media C. Baffert, V. Artero, M. Fontecave Inorg. Chem.. 2007, 46, 1817-1824 bz N Cy P bz N P Cy Cy P Ni P Cy bz N N CF3SO3H pKa= 2.6 bz H2/Et3N Eher = -0.4V vs Ag/AgCl Dubois et al. J. Am. Chem. Soc., 2006. One of the rare catalyst for H2 oxidation E =-0.27 vs Ag/AgCl N N N Ru A Ru-Co complex M N N N Acetone + 3h, T.A E /V vs Ag/AgCl -2 -1.5 -1 -0.5 CoI 0 0.5 1 CoII DMF 0.1M n-Bu4NBF4 as supporting electrolyte glassy carbon electrode, v = 100 mV.s-1 5µA H2 Photoproduction 60 acetone 50 TON 40 30 20 CH3CN 10 0 0 1 Hg lamp (> 350 nm) Acetone Et3N : 100 equiv. Et3NHBF4 : 100 equiv H2 : GC analysis 2 3 4 irradiation time /h Fihri, A.; Artero, V.; Razavet, M.; Baffert, C.; Leibl, W.; Fontecave, M., Cobaloxime-Based Photocatalytic devices for Hydrogen Production. Angewandte Chemie, International Edition 2008 ½ H2 Acetone 60 Et3N•+ 20 10 0 Et3N CH3OH H+ CH3CN 30 DMF 40 1,2-dichloroéthane 50 A tunable supramolecular system: 1. the coordination sphere 140 120 100 E°(Co II/CoI) = -0.9 V vs Ag/AgCl E°(Co II/CoI) = -0.41 V vs Ag/AgCl E°(CoII/CoI) = -0.23 V vs Ag/AgCl 80 60 40 20 0 TO N A tunable supramolecular complex 2. the linker + 2 TON 56 TON + exces dmgH2 17 TON 120 TON Fihri, Artero, Leibl, Fontecave, Angew. Chem. 2008 A tunable supramolecular complex 3. the photosensitizer Turnovers 9 > 380 nm 210 273 Fihri, Artero, Fontecave, Dalton Trans 2008 CH3CN Et3N TON = 56 Aqueous acetate buffer EDTA pH 5 TON = 4.8 Vos et al. Angew. Chem. Int. Ed. 2006. Sakai et al. J. Am. Chem. Soc. 2006. acetone Et3N TON = 120 CH3CN/H2O Dimethylaniline TON = 60 Brewer et al. J Am. Chem. Soc. 2007 Artero, Fontecave et al. Angew. Chem. Int. Ed. 2008. Aqueous buffer ascorbate TON = 20 The « Graal » : H2O as the source of electrons 2760 Bernhard JACS 2007 100-600 Thummel Inorg. Chem. 2008 TN: 250 Llobet [Ru(µ µ-OAc)(bpp)(terpy)2] Angew chem 2008, 47, 5830 Ce(IV) électrode M’ 500 Bonchio, Hill Angew. 2008 Co(PO4) Nocera Science 2008 1000 Dismukes Angew. 2008 Project GRAFTHYDRO Bio-inspired nanomaterials for Hydrogen evolution: towards alternatives to platinum nanoparticles H2 Laboratoire de Chimie et Biologie des métaux UMR 5249 CEA/CNRS Université Jospeh Fourier Marc Fontecave Vincent Artero Alan Legoff Laboratoire de Chimie des Surfaces et Interfaces CEA Saclay Serge Palacin Bruno Jousselme Photoelectrochemical cell: water photoelectrolysis 2H2O = O2 + 2H2 e- Cathode H+ H+ Photocathode H2O H+ O2 H2 Photoanode SC-n : Fe2O3/WO3 O2 or H2 Best catalysts: overvoltage, TOF,.. NH3+ NC pKa= 7,6 Eher = - 0.4 V vs Ag/AgCl in CH3CN 92 TON.h-1 (- 0.5 V) Cobaloximes as functional models for hydrogenases. 2. Proton electroreduction catalyzed by difluoroboryl-bis(dimethylglyoximato)-cobalt(II) complexes in organic media C. Baffert, V. Artero, M. Fontecave Inorg. Chem.. 2007, 46, 1817-1824 bz N Cy P bz N P Cy Cy P Ni P Cy bz N N CF3SO3H pKa= 2.6 bz H2/Et3N Dubois et al. J. Am. Chem. Soc., 2006. Eher = -0.4V vs Ag/AgCl One of the rare catalysts for H2 oxidation E =-0.27 vs Ag/AgCl Bio-inspired nanomaterials for Hydrogen evolution Hydrogenases Bio-inspired catalysts Electrocatalytic activity demonstrated in solution Dubois et al., J. Am. Chem. Soc. 2007,128, 358 European patent application EP-08 290 988.8 NOVEL MATERIALS AND THEIR USE FOR THE ELECTROCATALYTIC EVOLUTION OR UPTAKE OF H2 What about the electrocatalytic activity of the complexes grafted on the electrodes ??? MWNTs electrode functionalization with metal catalysts (Eher= -0.3 V vs Ag/AgCl) - 0.2 V RNH2 399.9 N 1s RNH3+ 401.6 Ni 200 Counts/s 2p3/2 856.0 2p1/2 873.9 P 2p 132.2 ITO 500 Counts/s 405 MWNTs 400 395 Binding energy (eV) 890 135 n = 1.5 10-9 mol.cm-2 880 130 X-ray Photoelectron Spectroscopy (XPS) Scanning Electron Microscopy (SEM) 870 860 Binding Energy (eV) 850 Electrocatalytic properties of the modified electrodes E /V vs Ag/AgCl H+ H2 -0,8 -0,6 -0,4 -0,2 0,0 0,2 [DMF-H]+ CH3CN e2OOµA -0.3 V (overvoltage: 0.2V) DMFH+: pKa=6.1 in CH3CN E°= - 0.1 V vs Ag/AgCl Controlled potential coulometry (-0.5 V vs Ag/AgCl) CH3CN /[DMFH](OTf) 60 mM GC analysis of H2 European patent application EP-08 290 988.8 Ni-ITO-MWCNT n = 1.5 10-9 mol.cm-2 >20.000 turnovers within 1h !! (6 s-1) 94% faradaic yield No evidence for loss of activity over hours Activity in water !! (N. Guillet, LITEN, CEA) Ring (Pt)- Disk(vitreous C + Nafion + Ni-NTC) configuration H2SO4 0.1 M Rotating-disk electrode measurements H2 evolution with 18 mV overvoltage Membrane (Nafion)- Gas Diffusion Layer (Ni-NTC) half-cell H2SO4 0.1 M A material compatible with PEM technology (Nafion membrane, Acidic conditions) Hydrogen: Water, Sun and Catalysts Marc Fontecave Laboratoire de Chimie et Biologie des Métaux, Université Joseph Fourier, CNRS, CEA/DSV/iRTSV CEA-Grenoble 17 rue des martyrs 38054 Grenoble cedex 9, France [email protected]; Phone: (0033)438789103 ; Fax: (0033)438789124 Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05 V. Artero Y. Oudart A. Fihri S. Canaguier A. Legoff