http://www.ANSERCenter.org

New Fuels: Artificial Photosynthesis

Future Transportation Fuels StudyNational Petroleum Council

Victoria L. Gunderson and Michael R. WasielewskiApril 20, 2011

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

Office of Science, U. S. DOE Basic Research Needs for Solar Energy Utilization. Report from Basic Energy Sciences Workshop on Solar Energy Utilization; 2005.

THE ENERGY SOURCES:• Petroleum• Natural Gas• Hydroelectric• Geothermal

• Wind• Nuclear• Solar

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 Fuels

Solar Cells Biomass, Artificial Systems

1.2 x 105 TW on Earth’s surface36,000 TW on land (world)

2,200 TW on land (US)

Photosynthesis

6CO2 + 6H2O C6H12O6 + 6O2

“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.”

Light Reactions

H2O

O2ATP NADPH, H+

ADPNADP+

Pi

CO2

Sugar

Calvin Cycle

Blankenship, Molecular Mechanics of Photosynthesis: 2002

Light Reactions

Chlorophylls

Reaction Center

Electron Transport Chain

Energy transfer

Electron transfer

Catalysis

Light harvesting

In a perfect world, photosynthesis would be perfect.Otto Warburg

Artificial Photosynthesis

Blankenship, Molecular Mechanics of Photosynthesis: 2002

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

Basics Artificial Photosynthetic Steps

Light Harvesting

Energy Transfer

Electron Transfer

Catalysis

Photovoltaics

Photovoltaics

Co

st ($$$)

www.nrel.gov

Basics Artificial Photosynthetic Steps

Light Harvesting

Energy Transfer

Electron Transfer

Catalysis

Water Oxidation Carbon Dioxide Reduction

H2 CH3OH, COFischer-TropschProcess

Photovoltaics

Catalysis

2H2O ↔ 2H2 + O2

2H2O ↔ O2 + 4H+ + 4e-

2H+ + 2e- ↔ H2

Water Splitting (Oxygen Evolution)

Proton Reduction (Hydrogen Evolution)

E° = 1.23 V vs NHE

Water Oxidation

Carbon Dioxide Reduction

CO2 + 2H+ + 2e- ↔ CO + H2O

CO2 + 6H+ + 6e- ↔ CH3OH + H2O

E° = -0.53 V vs. NHE

E° = -0.38 V vs. NHE

Current Technological Maturity

Sunlight Solar Cell Water Electrolyzer

Sunlight Fully Integrated System Fuel Output

Hambourger et al., Chem. Soc. Rev. 2009, 38, 25-35.

State-of-the-Art

Future Direction

(expensive and/or hazardous, < 13% efficient )

Fuel OutputCurrent

Players & Research: Centers

August 2008NFS Funds “Powering the

Plant: A Chemical Center for Innovation”

(13 Universities, BP Solar, Brookhaven, Southern California Edison)

August 2009DOE Funds 46 Frontier Energy

Research Centers (EFRCs)(27 EFRCs with some solar research, 7 largely

focused on solar research)

July 2010DOE establishes the Joint Center for

Artificial Photosynthesis (JCAP)(California Institute of Technology & Lawrence Berkeley

National Laboratory)

Including the Argonne-Northwestern Solar Energy Research (ANSER) Center

Players & Research: PIs

MaterialsPaul 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)

Theory/ModelingJames Muckerman (BNL)Jens Norskov (Stanford)

Mark Ratner (Northwestern)Gregory Voth (Univ. of Chicago)

ArchitecturesJon Birge (Univ. of Chicago)

Phil Krein (Illinois)Eric McFarland (UCSB)

** Not a comprehensive list

Players & Research: PIs

PhotovoltaicsJames 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)

Photodriven CatalysisHarry Gray (CalTech)

Devens Gust (Arizona State)Leif Hammarström (Uppsala)

Nate Lewis (CalTech)Michael Wasielewski (Northwestern)

PhotosynthesisJames Barber (Imperial)

Stenbjorn Styring (Uppsala)

PhotocatalysisBruce Brunschwig (Yale)Kazunari Domen (Tokyo)

Tom Meyer (UNC)Bruce Parkinson (Wyoming)

** Not a comprehensive list

Players & Research: PIs

Water SplittingAndrew Bocarsly (Princeton)

Gray Brudvig (Yale)G. Charles Dismukes (Rutgers)

Craig Hill (Emory)Daniel Nocera (MIT)

Proton ReductionFraser Armstrong (Oxford)

Mark Fontecave (CEA Grenoble)Vincent Artero (CEA Grenoble)

Marcetta Darensbourg (Texas A&M)

Catalysis (general)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)

CO2 ReductionDaniel DuBois (PNNL)

Etsuko Fujita (BNL)Clifford Kubiak (UCSD)

Peter Stair (Northwestern)

** 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

High Throughput Approach to Catalyst Screening

Woodhouse, M.; Parkinson, B. A., Chem. Soc. Rev. 2009, 38, 197-210. Jaramillo, T. F. et al, J. Combinatorial Chem. 2004, 7, 264-271.

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

PIs: Bruce Parkinson (Wyoming),Eric McFarland (UCSB), & Tom Jaramillo (Cal Tech)

Key Findings: #2

Self-healing, Self-assembling Oxygen-Evolving Catalyst

Kanan, M. W.; Surendranath, Y.; Nocera, D. G., Chem. Soc. Rev. 2009, 38, 109-114.

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

PI: Daniel Nocera (MIT)

Key Findings: #3

Molecular Level Understanding of Accumulative Electron Transfer

Magnuson, A. et al.., Acc. Chem. Res. 2009, 42, 1899-1909.

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

PI: Leif Hammarström (Uppsala)

Key Finding: #4

NN

O

O

O

O

N

C8H17

C8H17

NNH33C1

6

H33C16 O

O N

C8H17

C8H17

N NC16H33

C16H33

Self-Assembly of Photoactive Charge Conduits for Integrated Solar Fuels Systems

Wasielewski, M. R., Acc. Chem. Res. 2009, 42, 1910-1921.

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

PI: Michael Wasielewski (Northwestern)

Key Findings: #5

DuBois, M. R.; DuBois, D. L., Chem. Soc. Rev. 2009, 38, 62-72.

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

PI: Daniel DuBois (PNNL)

Key Findings: #6

Singlet Fission for Enhanced Charge Generation

Smith, M. B.; Michl, J., Chem. Rev. 2010, 110, 6891-6936.

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

PI: Josef Michl (Colorado-Boulder)

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.