New Fuels:
Artificial Photosynthesis
Future Transportation Fuels Study
National Petroleum Council
Victoria L. Gunderson and Michael R. Wasielewski
April 20, 2011
http://www.ANSERCenter.org
White Paper Outline

Motivation

What is Artificial Photosynthesis?

Current Technological Maturity

Players & Research

Challenges

Key Findings

Future Outlook
Global Energy: The Need
THE ENERGY NEED:
• 13 TW in 2004
• 30 TW in 2050
• 45 TW in 2100
THE ENERGY SOURCES:
• Petroleum
• Wind
• Natural Gas
• Nuclear
• Hydroelectric • Solar
• Geothermal
Office of Science, U. S. DOE Basic Research Needs for Solar Energy Utilization.
Report from Basic Energy Sciences Workshop on Solar Energy Utilization; 2005.
Global Energy: The Solution
In one hour enough energy
from sunlight strikes the
earth to meet the current
energy need of the planet
for an entire year
Electricity
Solar Cells
1.2 x 105 TW on Earth’s surface
36,000 TW on land (world)
2,200 TW on land (US)
Fuels
Biomass, Artificial Systems
Photosynthesis
“Photosynthesis is a process in which light
energy is captured and stored by an
organism, and then stored energy is used
to drive cellular processes.”
6CO2 + 6H2O  C6H12O6 + 6O2
H2O
Light Reactions
Light Reactions
O2
ATP NADPH, H+
Light harvesting
Chlorophylls
Pi
ADP
+
NADP
CO2
Energy transfer
Reaction Center
Catalysis
Calvin Cycle
Electron transfer
Electron Transport Chain
Sugar
Blankenship, Molecular Mechanics of Photosynthesis: 2002
Artificial Photosynthesis
In a perfect world, photosynthesis would be perfect.
Otto Warburg
Natural Photosynthesis is only about
1% efficient overall
Need to develop modified natural and
artificial photosynthetic systems
that are >10% efficient for carbon
neutral formation of
H2, CH4, CH3OH and C2H5OH
Blankenship, Molecular Mechanics of Photosynthesis: 2002
Basics Artificial Photosynthetic Steps
Light Harvesting
Energy Transfer
Photovoltaics
Electron Transfer
Catalysis
Photovoltaics
 Cost ($$$)
www.nrel.gov
Basics Artificial Photosynthetic Steps
Light Harvesting
Energy Transfer
Photovoltaics
Electron Transfer
Catalysis
Water Oxidation
H2
Carbon Dioxide Reduction
Fischer-Tropsch
Process
CH3OH, CO
Catalysis
Water Oxidation
2H2O ↔ 2H2 + O2
2H2O ↔ O2 + 4H+ + 4e2H+ + 2e- ↔ H2
E° = 1.23 V vs NHE
Water Splitting (Oxygen Evolution)
Proton Reduction (Hydrogen Evolution)
Carbon Dioxide Reduction
CO2 + 2H+ + 2e- ↔ CO + H2O
E° = -0.53 V vs. NHE
CO2 + 6H+ + 6e- ↔ CH3OH + H2O
E° = -0.38 V vs. NHE
Current Technological Maturity
State-of-the-Art
Sunlight
(expensive and/or hazardous, < 13% efficient )
Solar Cell
Current
Water Electrolyzer
Fuel Output
Future Direction
Sunlight
Fully Integrated System
Fuel Output
Hambourger et al., Chem. Soc. Rev. 2009, 38, 25-35.
Players & Research: Centers
August 2008
NFS Funds “Powering the
Plant: A Chemical Center for
Innovation”
(13 Universities, BP Solar, Brookhaven,
Southern California Edison)
July 2010
DOE establishes the Joint Center for
Artificial Photosynthesis (JCAP)
(California Institute of Technology & Lawrence Berkeley
National Laboratory)
August 2009
DOE Funds 46 Frontier Energy
Research Centers (EFRCs)
(27 EFRCs with some solar research, 7 largely
focused on solar research)
Including the ArgonneNorthwestern Solar
Energy Research
(ANSER) Center
Players & Research: PIs
Theory/Modeling
James Muckerman (BNL)
Jens Norskov (Stanford)
Mark Ratner (Northwestern)
Gregory Voth (Univ. of Chicago)
Architectures
Jon Birge (Univ. of Chicago)
Phil Krein (Illinois)
Eric McFarland (UCSB)
Materials
Paul Alivisatos (LBL)
Harry Atwater (CalTech)
Thomas Mallouk (Penn State)
Anna Moore (Arizona State)
Tom Moore (Arizona State)
Klaus Müllen (Max Planck)
Michael Pellin (Argonne)
John Rogers (Illinois)
Frank Würthner (Würzburg)
Peidong Yang (Berkeley)
Luping Yu (Univ. of Chicago)
** Not a comprehensive list
Players & Research: PIs
Photocatalysis
Photovoltaics
James Durrant (Imperial)
Stephen Forrest (Michigan)
Michael Grätzel (Lausanne)
Joseph Hupp (Northwestern)
Ghassen Jabbour (KAUST)
Rene Janssen (Eindhoven)
Michio Kondo (AIST)
Tobin Marks (Northwestern)
Michael McGehee (Stanford)
Art Nozik (NREL)
Ralph Nuzzo (Illinois)
Garry Rumbles (NREL)
John Turner (NREL)
Peng Wang (CIAC)
Bruce Brunschwig (Yale)
Kazunari Domen (Tokyo)
Tom Meyer (UNC)
Bruce Parkinson (Wyoming)
Photodriven Catalysis
Harry Gray (CalTech)
Devens Gust (Arizona State)
Leif Hammarström (Uppsala)
Nate Lewis (CalTech)
Michael Wasielewski (Northwestern)
Photosynthesis
James Barber (Imperial)
Stenbjorn Styring (Uppsala)
** Not a comprehensive list
Players & Research: PIs
Water Splitting
Andrew Bocarsly (Princeton)
Gray Brudvig (Yale)
G. Charles Dismukes (Rutgers)
Craig Hill (Emory)
Daniel Nocera (MIT)
Proton Reduction
Fraser Armstrong (Oxford)
Mark Fontecave (CEA Grenoble)
Vincent Artero (CEA Grenoble)
Marcetta Darensbourg (Texas A&M)
Catalysis (general)
CO2 Reduction
Daniel DuBois (PNNL)
Etsuko Fujita (BNL)
Clifford Kubiak (UCSD)
Peter Stair (Northwestern)
Lin Chen (ANL/Northwestern)
Allen Bard (Texas)
Jeffrey Long (Berkeley)
Wolfgang Lubitz (Max Planck)
David Milstein (Weizmann)
Jonas Peters (Cal Tech)
Notker Roesch (Munich)
T. Don Tilley (Berkeley)
Junko Yano (LBL)
** Not a comprehensive list
Challenges
- Development of high performance, cost-effective light absorbing
materials for use in photovoltaics
- Discovery and development of cost-effective catalysts that have
long-term stability and can be linked to photovoltaic technologies
- Design and discovery of interconnected membrane networks that
provide a physical support network for the overall process
- Design of interfacial materials that link light absorbers to catalysts
to allow for efficient control of the integrated system
- Development and design of architectures that allow for scaling-up
from the nanoscale to the macroscale
Key Findings: #1
PIs: Bruce Parkinson (Wyoming),
Eric McFarland (UCSB), & Tom Jaramillo (Cal Tech)
High Throughput Approach to Catalyst Screening
Objective: Find stable, robust,
earth-abundant photoanodes
for water oxidation
Method: Catalyst screening
with an automated
electrochemical deposition of
metal oxides
Results: A critical innovation for
rapid identification of water
oxidation catalysts
Woodhouse, M.; Parkinson, B. A., Chem. Soc. Rev. 2009, 38, 197-210.
Jaramillo, T. F. et al, J. Combinatorial Chem. 2004, 7, 264-271.
Key Findings: #2
PI: Daniel Nocera (MIT)
Self-healing, Self-assembling Oxygen-Evolving Catalyst
Objective: Find stable, robust,
earth-abundant catalyst for
water oxidation
Method: Synthesize catalysts
and study their catalytic
properties using
electrochemistry
Results: Cobalt-phosphate
catalyst self-assembles and
oxidizes water over a wide pH
range with self-healing
properties
Kanan, M. W.; Surendranath, Y.; Nocera, D. G., Chem. Soc. Rev. 2009, 38, 109-114.
Key Findings: #3
PI: Leif Hammarström (Uppsala)
Molecular Level Understanding of Accumulative
Electron Transfer
Objective: Understand the
basic photophysics of
photodriven molecular catalysis
Method: Synthesized PSII
molecular mimics and used
ultrafast laser spectroscopy to
quantify photophysics
Results: Observed multi-step
electron transfer to PSII mimic,
demonstrates inherent
complexity of photodriven
catalysis
Magnuson, A. et al.., Acc. Chem. Res. 2009, 42, 1899-1909.
Key Finding: #4PI: Michael Wasielewski (Northwestern)
Self-Assembly of Photoactive Charge Conduits for
Integrated Solar Fuels Systems
Objective: Generate functional
self-assembling molecular
conduits
Method: Synthesize molecular
systems and use ultrafast laser
spectroscopy to determine
photophysics
Results: Self-assembling
donor-acceptor systems show
efficient light harvesting and
electron transfer
C 8H 17
H 33C1
6
N
H 33C1
N
O
N
O
O
N
N
C 8H17
6
C 8H17
O
O
C 16H 33
O
N
N
N
C 16H 33
C8H 17
Wasielewski, M. R., Acc. Chem. Res. 2009, 42, 1910-1921.
Key Findings: #5
PI: Daniel DuBois (PNNL)
Pendant Base Incorporation in Molecular Catalysts
for Hydrogen Production
Objective: Find stable, robust,
earth-abundant catalyst for
hydrogen evolution
Method: Mechanistic studies of
nickel/cobalt catalysts
Results: Pendant base
incorporation facilitates
proton/hydride interactions and
help tune electronic/steric
properties
DuBois, M. R.; DuBois, D. L., Chem. Soc. Rev. 2009, 38, 62-72.
Key Findings: #6
PI: Josef Michl (Colorado-Boulder)
Singlet Fission for Enhanced Charge Generation
Objective: Improve overall
power conversion efficiencies of
organic PVs
Method: Identify molecules that
yield higher energy conversion
rates
Results: Molecules that
undergo singlet fission increase
theoretical power efficiencies
and a few molecules have been
shown to undergo this process
Smith, M. B.; Michl, J., Chem. Rev. 2010, 110, 6891-6936.
Future Outlook
Promising emergent technology to impact future
transportation fuels
The technology is not currently economically viable.
R&D efforts are extensive, which presents a positive
future outlook for a large solar fuels impact.
Technology output qualitative timeline:
1. Hydrogen generation and conversion to hydrocarbon fuels as the initial
first technology established through wired PV-Electrolyzer device.
2. CO2 reduction poses a more difficult scientific challenge, but offers the
potential for the largest future impact (to provide a fuel source & mitigate
climate change).
3. Fully integrated artificial photosynthetic system is ideal, but will take
significant chemical consideration & engineering effort.
Sunrise or Sunset?
Acknowledgement
This work was supported as part of the ANSER Center,
an Energy Frontier Research Center funded by the U.S.
Department of Energy, Office of Science, Office of Basic
Energy Sciences, under Award Number DE-SC0001059.