Our Energy Future. Science and Technology Challenges of the 21st Century
Solar Fuels and Next Generation Photovoltaics:
The UNC-CH Energy Frontier gyResearch Center
(UNC (UNC 10-4-05)UNC Energy Frontier UNC
((UNC 10-4-05)U C e gy o t eResearch Center
TJ Meyer
11/15/2010 - 1
Duke-CTMS-11-12-10
Fossil Fuels: plentiful now and dominate as an energy source (peak oil- 2008-2025?)
Where will the energy come
11/15/2010 - 2
Cicerone- NAS- April, 28, 2008
from?
Environmental Impacts. The greenhouse gas effect.g g
Solar radiation passes through the atmosphere
Earth radiates energy back into space. Atmospheric greenhouse gases the atmosphere
and heats the earth.
Atmospheric greenhouse gases trap some outgoing energy, retaining heat.
UN Inter-
Greenhouse Gas EffectGreenhouse Gas Effect
UN Inter-governmental Panel on Climate Change (10-
Increased concentrations Increased concentrations of greenhouse gases of greenhouse gases ––carbon dioxide, carbon dioxide,
Increased concentrations Increased concentrations of greenhouse gases of greenhouse gases ––carbon dioxide, carbon dioxide,
Greenhouse Gas EffectGreenhouse Gas Effectg (2007), NAS (9-2010)-”Global warming is ,,
sulfur dioxide, sulfur dioxide, nitrous oxide, nitrous oxide, methane, mercurymethane, mercury ––enhance the earth’s heatenhance the earth’s heat--
,,sulfur dioxide, sulfur dioxide, nitrous oxide, nitrous oxide, methane, mercurymethane, mercury ––enhance the earth’s heatenhance the earth’s heat--
warming is unequivocal”
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trapping ability impacting trapping ability impacting global warming.global warming.trapping ability impacting trapping ability impacting global warming.global warming.At what cost?
Sea Level Rise
Sea level rise could be between 2.5 and 6.2 ft by the end of th t (P di f th N ti l A d fthe century (Proceedings of the National Academy of Sciences, 12/9)
ManhattanManhattan
Coastal North Carolina
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Energy and Environment: Strategy For a New Energy Future
• Utilize all energy options:– Clean coal
Shale and tar sands
•Our Energy Future:- increased
– Shale and tar sands– Coupled with CO2 capture
and storage (sequestration)N l
efficiency - minimize impact- sustainability.
– Nuclear – Hydrogen and fuel cells– Renewable energy
solar
•Transition from petroleum for transportation(wind, solar, biomass,
geothermal)Energy use and infrastructure:
E t
transportation.
•Large scale, viable energy options:– Energy storage
– Efficiency and conservation – Energy and environmental
d li
energy options:Solar, nuclear, and hydrocarbons with sequestration.
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modeling– Water for energy
q
Solar Energy: ~10,000 Times Current Energy Use but Requires Energy Storage
•Solar Energy isDiffuse: ~60,000 ,sq miles to meet current US power demands (3 TW)*
3 TW
demands (3 TW) Intermittent: 6 hours of useful
20 TWsunlight per day
RequiresRequires Energy Storage
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Storage
*at 10% efficiency, NREL. $60 Trillion at $400/m2.
Solar Energy. PhotovoltaicsCurrent Use US: 1/8%; 30¢/KWHCurrent Use US: 1/8%; 30¢/KWH
Solar Panels
Dow Solar ShinglesOPVOrganic Photovoltaics (OPV)
90% of US homes use asphaltshingles. Solar shingles could provide 40 80% of home
Organic Photovoltaics (OPV)
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provide 40-80% of home electricity consumption.
Energy Storage with Solar Fuels
Hydrogen, CO, natural gas, liquid hydrocarbons and oxygenatesand oxygenates
2 H2O + 4 hν 2H2 + O2(∆Go = 4 92 eV n = 4)(∆Go = 4.92 eV, n = 4)
2 H O + CO + 8 hν CH + 2O2 H2O + CO2 + 8 hν CH4 + 2O2(∆Go = 10.3 eV, n = 8)
• Spin-Offs: load leveling; energy storage• Uses: existing energy infrastructure.
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Natural Gas Power Plants.A Closed Cycle with Solar Fuels
CH4 + O2
CO2 + H2O11/15/2010 - 92 H2O + CO2 + 8 hν CH4 + 2O2
Photosynthesis. Chloroplast Structure
5
(~5 μ; 1-1000/cell)
Solar driven water reduction of COSolar driven water reduction of CO2 occurs in the
666 2612622 OOHCCOOH +→+
Solar driven water reduction of CO2.thylakoid membrane of chloroplasts.
11/15/2010 - 10
Voet and Voet 24-1
)/675;/2820(1.29 molkcalmolkjouleseVGo =Δ
UNC EFRCUNC EFRC
DOE: DOE: Solar Fuels & Next Generation Solar Fuels & Next Generation Photovoltaics: $17.5 M/5 yrsPhotovoltaics: $17.5 M/5 yrsPhotovoltaics: $17.5 M/5 yrsPhotovoltaics: $17.5 M/5 yrs
“Integrating skills and talents of multiple investigators to “Integrating skills and talents of multiple investigators to enable fundamental research at a level of scope and complexity enable fundamental research at a level of scope and complexity not possible with individual or small group research projects”not possible with individual or small group research projects”
PeoplePeople 26 faculty, 7 scientific staff13 postdocs, 20 grad students, 15 affiliates
p g p p jp g p p j
CollaborationsCollaborations Duke, NCSU, NCCU, U. Florida, RTI
PartnershipsPartnerships Research Triangle Institute, Research T i l E C ti (RTEC) Triangle Energy Consortium (RTEC), Research Triangle Solar Fuels Institute (RTSFI), National Instruments, DuPont
User Facilities User Facilities Spectroscopy, Fabrication & Photolysis
OrganizationOrganization
EFRC DirectorMeyer
Deputy DirectorPapanikolas
Executive CommitteeMeyer 1 Papanikolas
Meyer, Papanikolas, Schauer, Schanze 2, Lin,
Beratan 2, Pinschmidt
LinSchanze 2
Research CouncilMeyer, Papanikolas,
Schanze 2, Lin, Lopez,Brookhart, Forbes, Murray SamulskiMurray 1 Brookhart 1 Forbes Samulski LopezBeratan 2
Solar Fuels Materials Next Generation Photovoltaics
Catalysis Interfacial Structure & Dynamics
Murray, SamulskiMurray Brookhart Forbes Samulski LopezBeratan
1. Member National Academy of Sciences2. Collaborating Partner Institution
(Lin/Lopez/Samulski) (Papanikolas/Schanze 2 )(Brookhart/Meyer/Murray) (Forbes/Papanikolas)
EFRC RESEARCHEFRC RESEARCH
Solar Fuels Materials
Next Generation Photovoltaics
Catalysis Interfacial Structure & Dynamics
Water Oxidation
(Lin/Lopez/Samulski) (Papanikolas/Schanze*)(Brookhart/Meyer/Murray)y
(Forbes/Papanikolas)
CO2 Reduction
InterfaceDynamics
Interfacial Structure
Framework Materials
Semi-conductors
Polymers Peptides OPVTheory DSSC/DS-PEC Devices
Solar Fuels OPV
Chemical Approaches to Artificial Photosynthesis. Modular Approach
• Light absorption, sensitization • Electron transfer quenchingq g• Vectorial electron/proton transfer, redox splitting
• Catalysis of water oxidation and reduction• Catalysis of water oxidation and reduction
Photosystem II4 h Li ht
2 H O 2 H4 e-
4 hν Light HarvestingAntenna
4 e-O-O bondformation
Alstrum-Acevedo, Brennaman, Meyer, Inorg. Chem. 2005,
Meyer, Accounts of Chemical Research1989, 22, 163.
2 H2O
O2
4 H+
2 H2
CatOx D CatRedA
4 e4 e
PCETPCET
4 H++
formation
Multi e-
catalysis ET interfaceMulti e-
catalysis
C
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g ,44, 6802.
Proton Transfer
cata ys s ET interface cata ys s
Meyer, et. al. Inorg. Chem. 2005, 6802; Accounts Chem Res 1989, 163.
Dye Sensitized Photoelectrosynthesis Cells (DSPEC)
CO2 + e‐ e‐e‐ e‐
e‐
PEM1/2 H2O 1/2 H2
TiO2 hν
hνe-
1/2 H2O
4H2O
2O2 + 8H+
8H+e ee e
hνCH4
+ 2H2O
*C CatOxD CatRed
e-
1/4 O2 + H+
e- e-
H+
TiO2
1/4O2 + H+
Modular: Assemble Critical Elements:
e- e-
- molecular/nano light absorption- electron transfer, catalyst activation- water oxidation; water/H+/CO2 reduction
CT
RO
DE
Design-Translational Issues:- materials, materials properties, synthesis, scale up- device design and evaluation- engineering and scale up
ELE
C
- engineering and scale up
Catalysis. Catalysis. Water Water OxidationOxidation
Catalysis
(Brookhart/Meyer/Murray)- Rates
P th R t2 H2O - 4 e- - 4 H+ → O2
Water Oxidation
CO2 Reduction
- Pathways. Rate enhancements of > 104of > 10- Characterizationof Intermediates
Yang, et al
CatalysisCatalysis
Catalysis
(Brookhart/Meyer/Murray)Retention of reactivity on oxide electrodes and semiconductors
Water Oxidation
CO2 Reduction Nano ITO
Pd(0) Morphology: Controlled by Electrodeposition Scan Rate
Bakir, M.; Sullivan, B. P.; MacKay, S.; Linton, R. W.; Meyer, T. J. Chem. Mater. 1996, 8, 2461-2467.
CO Reduction: CO + 8 e- + 8 H+→ CH + 2 H O10 mV/s 500 mV/s
( ) p gy y p
[FeII(vbpy)3][PF6]2
reductive cyclingbetween -0.45 Vand -1.45 V
poly-[FeII(vbpy)3][PF6]2(electrode-supported)
0.1 M [NEt4][CN] poly-[FeII(vbpy)2(CN)2],poly-(vbpy)
(electrode-supported)CH3CN PdIICl2(PhCN)2[NB ][PF ]
reductive cyclingbetween -0.45 Vand -1.45 V
poly-[FeII(vbpy)3][PF6]2 / Pd0
(electrode-supported)
CO2 Reduction: CO2 + 8 e + 8 H → CH4 + 2 H2O
• High surface area polymer stabilized M(0) electrodes
• Metal complexes in
[NBu4][PF6]CH3CN
5.0 μm 3.0 μm
solution and on surfaces
• Pyridine catalysis
Interfacial Structure Interfacial Structure and Dynanicsand Dynanics
Interfacial Structure & Dynamics
(Forbes/Papanikolas)Catalyst
hvET
InterfaceDynamics
Interfacial Structure DSSC/DS-
PEC Devices
CatalystET
H O
O2 +H+
Chromophore H2O
Integrated molecular assemblies and- Integrated molecular assemblies and nano-structures
- Surface binding and stability- Rates and Efficiencies: Injection and backRates and Efficiencies: Injection and back
electron transfer in chromophore-catalyst assemblies on TiO2 and new oxide semiconductors (e.g. Nb2O5).W ki d i- Working devices: or assemblies under device conditions.
Interfacial Structure Interfacial Structure and Dynanicsand Dynanics
Chromophore-Catalyst assemblies • Maximize solar absorption
Interfacial Structure & Dynamics
(Forbes/Papanikolas)• Maximize device dynamics Concentrate, store, and use multiple photons/redox equivalents
• Rapid rates, robust performance• Surface stable
(Forbes/Papanikolas)
InterfaceDynamics
Interfacial Structure DSSC/DS-
PEC
PO
HOHO
4+
POHO
HO
4+
• Surface stable• Process engineering• Large scale arrays
Devices
RuN
NN
NN
N
POH
O
PO
OH
O
HOOH
RuN
NN
NN
N
P
POH
O
PO
OHHOOH
NN
N N
N
PO
OHHON
N
PO
OHHO
NRu
NN
OH2Ru
NN
N OH2
NN
Interfacial Structure Interfacial Structure and Dynanicsand Dynanics
Interfacial Structure & Dynamics
(Forbes/Papanikolas)1MLCTCB Injection
O +H+
InterfaceDynamics
Interfacial Structure DSSC/DS-
PEC Devices
3MLCT
hv
TransportET
Catalyst
H O
O2 +H+
GS
BETH2O
Catalysis
Challenge: Wide Range of Time Scales
VBBET
ET
Transport
semiconductor
10-15 10-12 10-9 10-6 10-3 100
Injection
Time (s)
Interfacial Structure Interfacial Structure and Dynanicsand Dynanics
Transient Grating MoranInterfacial Structure
& Dynamics(Forbes/Papanikolas)
Transient AbsorptionVis Pump / Vis-NIR Probe
Femtosecond Stimulated Raman ScatteringFSRS Papanikolas/Moran
PapanikolasInterfaceDynamics
Interfacial Structure DSSC/DS-
PEC Devices
Transient AbsorptionVis Pump / Vis-NIR Probe Papanikolas
Transient EmissionTCSPC or Streak Camera Papanikolas
Transient AbsorptionLow light/Ultrasensitive DetectionBrennaman/Meyer
Transient AbsorptionGated CCD DetectionBrennaman/Meyer
Low-light/Ultrasensitive Detection
Transient Near-IRStep-Scan Detection
Transient Photocurrent/Photovoltage
Brennaman/Meyer
Brennaman/Meyer
Brennaman/Meyer
10-15 10-12 10-9 10-6 10-3 100
Time (s)
y
Dye Sensitized Dye Sensitized PhotoelectrosynthesisPhotoelectrosynthesisCells (DSPEC)Cells (DSPEC)
I. DYE SENSITIZED PHOTOELECTROSYNTHESIS CELLS FOR SOLAR FUELS PRODUCTIONCatalyst Development Molecular Catalysts for Water Oxidation - Photostable, high turnover
Catalytic Materials for Water Oxidation - In solution & at interfacesCatalysts for CO Reduction to useful fuelsCatalysts for CO2 Reduction - to useful fuels
Materials Development New Metal Oxide Electrode Materials Assembly Development Chromophore-Redox Mediator-Catalyst Assemblies Integration & Device Development Solar Fuels Devices - Dye Sensitized Photoelectrochemical Cells (DS PEC)
Fundamental Studies Interfacial dynamics
Interfacial Structure & Dynamics
(Forbes/Papanikolas)
4H2OCO2 + 8H+e‐ e‐e‐ ‐
e‐
PEMInterfaceDynamics
Interfacial Structure DSSC/DS-
PEC Devices2 8H+e ee e‐
*
C CatOxD CatRed
CB
2O2 + 8H+hν CH4 + 2H2OVB
Dye Sensitized Dye Sensitized PhotoelectrosynthesisPhotoelectrosynthesisCells (DSPEC)Cells (DSPEC)
• Maximize solar absorption - to ~900 nm (1.38 eV) for single photon absorption; 40% efficiencies
• Maximize device dynamics - control of structure and energetics • Concentrate, store, and use multiple photons/redox
equivalents - for water oxidation; water/H+/CO2 reduction• Rates - exceed rates of solar insolation, ~10 mA/cm2
• Robust performance >2x1010 cycles/annum• Process engineering – product separation & scale up• Large scale arrays
Interfacial Structure & Dynamics
(Forbes/Papanikolas)
InterfaceDynamics
Interfacial Structure DSSC/DS-
PECPEC Devices
Dye Sensitized Solar Cells Dye Sensitized Solar Cells (DSSC)(DSSC)
GOALS•Increase V with Nb2O5 otherIncrease Voc with Nb2O5 other
semiconductors•Ditto with new dyes and
redox carriers•Tandem cells with
photoanodesand cathodes
Interfacial Structure
Gratzel- Accounts Chemical Research 2009
& Dynamics(Forbes/Papanikolas)
InterfaceDynamics
Interfacial Structure DSSC/DSDynamicsStructure DSSC/DS-
PEC Devices
Framework Materials• Synthetic tunability of framework
Wave Wang, to be submitted to JACS
Synthetic tunability of frameworkmaterials at the molecular level allows optimization of individual catalysts for proton/CO2reduction and water oxidation.reduction and water oxidation.
•The photon collection efficiency of light-harvesting framework materials can be similarly
ti i dCaleb Kent, JACS, ASAP
optimized.
• Integration of light antenna and catalysts into framework materials should enable photocatalytic total water splitting without relying on sacrificial reagents.
Solar Fuels Materials
(Lin/Lopez/Samulski)
Framework Materials
Semi-conductors
SemiconductorsSemiconductors
GOALSA) Oxide semiconductors with desirable band energy properties for photoanodes and photocathodes in solar fuel applications: e g COphotoanodes and photocathodes in solar fuel applications: e.g., CO2
reduction with Nb2O5, SrTiO3.
B) Delineate transport properties and tailor them to achieve good injection ) e eate t a spo t p ope t es a d ta o t e to ac e e good ject ocharacteristics and large surface areas minimizing optical and electronic loses.
Traditional sintered nanoparticles
UNC improved structure
Solar Fuels Materials
(Lin/Lopez/Samulski)
Framework Materials
Semi-conductors
Next Generation Next Generation PhovoltaicsPhovoltaics
II. NEXT GENERATION PHOTOVOLTAICSComponent Development Light-Harvesting Systems – High stability, efficient energy transport
Nanostructured Electrodes for Photovoltaic ApplicationsNanostructured Electrodes for Photovoltaic ApplicationsIntegrated Systems Integrated Assemblies – derivatized polymer & polypeptide scaffolds with multiple
chromophores & electron transfer donors & acceptorSurface Attachment – to semiconductor oxides
Device Development Next Generation Photovoltaic Devices
Nano-structured Photonic Electrode
hνNext Generation
PhotovoltaicsLight Harvesting
Antenna
Hole Transport
Photovoltaics (Papanikolas/Schanze*)
Polymers Peptides OPVHole Transport
Channel
PolymersPolymers
Specific Properties:---Energy + Charge transport---Surface active for attachment to metal-oxide surface Next Generation---Surface active for attachment to metal-oxide surface---Self-assembly
Next Generation Photovoltaics
(Papanikolas/Schanze*)
Polymers Peptides OPVPolymers Peptides OPV
OligopeptidesOligopeptides
- Controlled structures: Stepwise synthesis
- Molecular Modeling: calculated structures
- Inter- and intra-coil: energy, ET d idynamics
- Binding to oxide semi-conductor: TiO2, ZnO.
- Single molecule microscopy- Single molecule microscopyon surfaces
- Injection back ET: Ultrafast emission and absorption:emission and absorption:
Next Generation Photovoltaics
(Papanikolas/Schanze*)
Polymers Peptides OPV
Bulk Heterojunction Polymer Solar Cells
Next Generation Photovoltaics
(Papanikolas/Schanze*)
Polymers Peptides OPV
• New architecturesN d
Durrant, J. MRS Bulletin 2008, 33, 670• New donors• Carbon nanotubes
11/15/2010 - 30
30
TheoryTheory
• Reaction pathways, barriers, MM, QM: water oxidation, CO2 reductionEl t t f h i i i id• Electron-energy transfer mechanisms in rigid media
• Interfacial structure and dynamicshν Energy
transfer
• Modeling and simulation • Device performance
•Beratan- mechanism(s) of triplet triplet excitationof triplet-triplet excitation energy transfer in metal-organic frameworks and relatedmaterials.materials.
Theory. Theory. CurrentCurrent
•Models for multi-pathway Dexter mechanism: excitation transfer for MOFs and peptides.•Predict and estimate pKa values for transition metal hydrides.p a y•Energy migration in multi-chromophore coiled-coil peptides. •Calculation of pKas and redox potentials.•Calculate pathways for catalytic CO2 reduction.•Simulations for the complete catalytic water oxidation cycle by single-site ruthenium catalysts.
D* A*
B*
* *
B*Energy
D
D
A
A
D
D*
A
A*
B B
Dexter energy transfer pathways.
From Photons to FuelsFrom Photons to Fuels
Catalyst Design & DevelopmentCatalyst Design & Development•• Water Oxidation CatalystsWater Oxidation Catalysts
SCIENCESCIENCE
•• Water Oxidation CatalystsWater Oxidation Catalysts•• COCO2 2 Reduction CatalystsReduction Catalysts
Component Design & DevelopmentComponent Design & Development•• LightLight--Harvesting SystemsHarvesting Systems•• Metal Oxide ElectrodesMetal Oxide Electrodes
IntegrationIntegrationTranslational Translational
ResearchResearch gg•• Light Harvesting/Catalyst IntegrationLight Harvesting/Catalyst Integration•• Surface AttachmentSurface Attachment
DevicesDevicesDevicesDevices•• Photoelectrochemical CellPhotoelectrochemical Cell
Design & DevelopmentDesign & Development
DEVICESDEVICESDEVICESDEVICESRTI, RTSFI, Venture Capital, Industrial Partners
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