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The DOE Science News Source is a Newswise initiative to promote research news from the Office of Science of the DOE to the public and news media.
  • 2017-08-30 09:00:33
  • Article ID: 680275

Two for the Price of One: Exceeding 100 Percent Efficiency in Solar Fuel Production

Scientists capture excess light energy to produce fuel, essentially storing sunlight's energy for a rainy day.

  • Credit: Image courtesy of Yan et al., Nature Energy 2, 17052 (2017)

    When lead sulfide (PbS) quantum dots (QDs) absorb high-energy photons (right), two electron-hole pairs can be produced. Both electron-hole pairs can participate in chemical reactions (left) to produce hydrogen fuel.

The Science

In conventional systems for converting sunlight to chemical fuels, a single photon, no matter how energetic, leads to a single electron-hole pair and thus a single electron-hole pair’s worth of chemical work. The one-to-one situation limits devices that use sunlight to create chemical fuels. Scientists have overcome this limit. They demonstrated for the first time that two electron-hole pairs, and two electron-hole pair’s worth of chemical work, can be produced from a single photon.

The Impact

This research could make the conversion of sunlight into chemical fuels more efficient by harvesting more energy from highly energetic photons. Conventional systems discard this excess energy as heat. Higher efficiency, in turn, means lower cost. Why? It lets the device produce more fuel per unit area of the solar cell and of the land supporting the cell.

Summary

In conventional semiconductor-based energy harvesting of photons from the sun, excess photon energy above the semiconductor bandgap is wasted. Recently, scientists showed that semiconductor quantum dots could enable harvesting of the excess photon energy through multiple exciton generation: greater than 100 percent external quantum efficiency, a signature of multiple exciton generation, for producing electricity from light was demonstrated in a solar photovoltaic cell. In this work, scientists demonstrated greater than 100 percent external quantum efficiency in a solar photoelectrochemical cell, the first example of enhanced yield of a chemical reaction by multiple exciton generation. The photoelectrochemical cell consisted of a lead sulfide (PbS) quantum dot photoelectrode deposited from solution using a layer-by-layer approach on top of a patterned sol-gel TiO2/FTO (F-doped SnO2) coated glass slide. The team demonstrated hydrogen evolution from aqueous Na2S solutions with external quantum efficiencies greater than 100 percent for quantum dot photoelectrodes with band gap energies of 0.85, 0.92 and 1.08 eV, and for incident photon energies greater than 2.7 times the bandgap energy.

Funding

Funding for this work was provided by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences. Y.Y, R.W.C., B.D.C, G.F.P., A.R.M, and M.C.B acknowledge support from the Center for Advanced Solar Photophysics (CASP), an Energy Frontier Research Center, and J.G. and J.A.T. acknowledge support from the Solar Photochemistry program within the Division of Chemical Sciences, Geosciences, and Biosciences. Work at the National Renewable Energy Laboratory is supported by DOE through contract DE-AC36-08GO28308.

Publications

Y. Yan, R.W. Crisp, J. Gu, B.D. Chernomodik, G.F. Pach, A.R. Marshall, J.A. Turner, and M.C. Beard, “Multiple exciton generation for photoelectrochemical hydrogen evolution reactions with quantum yields exceeding 100%External link.” Nature Energy 2, 17052 (2017). [DOI: 10.1038/nenergy.2017.52]

O.E. Semonin, J.M. Luther, S. Choi, H.Y. Chen, J. Gao, A.J. Nozik, and M.C. Beard, “Peak external photocurrent quantum efficiency exceeding 100% via MEG in a quantum dot solar cellExternal link.” Science 334, 1530 (2011). [DOI: 10.1126/science.1209845]

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Large Outdoor Study Shows Biodiversity Improves Stability of Algal Biofuel Systems

A diverse mix of species improves the stability and fuel-oil yield of algal biofuel systems, as well as their resistance to invasion by outsiders, according to the findings of a federally funded outdoor study by University of Michigan researchers.

SLAC, Stanford Scientists Discover How a Hardy Microbe's Crystalline Shell Helps it Reel in Food

SLAC and Stanford scientists have discovered how some archaea thrive where other organisms would starve: Their crystalline shells not only protect them from the environment, but they also draw in nutrients through nanosized pores. Those nutrients concentrate in the space between the shell and the microbial cell, so what looks like a famine turns into a feast.

Critical plant gene takes unexpected detour that could boost biofuel yields

For decades, biologists have believed a key enzyme in plants had one function--produce amino acids, which are vital to plant survival and also essential to human diets. But for Wellington Muchero, Meng Xie and their colleagues, this enzyme does more than advertised. They had run a series of experiments on poplar plants that consistently revealed mutations in a structure of the life-sustaining enzyme that was not previously known to exist.

How Microgrids Could Boost Resilience in New Orleans

In a year-long project, researchers at Sandia and Los Alamos national laboratories teamed up with the City of New Orleans to analyze ways to increase community resilience and improve the availability of critical lifeline services during and after severe weather. The team used historical hurricane scenarios to model how storms cause localized flooding, disrupt the electrical system and cut off parts of the community from lifeline services. Sandia researchers then developed a tool to analyze and identify existing clusters of businesses and community resources in areas less prone to inundation -- such as gas stations, grocery stores and pharmacies that could be outfitted with microgrids to boost resilience.

NIF Experiments Blast Previous Record and Double Fusion Yield

An experimental campaign conducted at the National Ignition Facility (NIF) - the world's largest and most energetic laser - has achieved a total fusion neutron yield of 1.9e16 (1.9x1016) and 54 KJ of fusion energy output - double the previous record. The experiments utilized a diamond capsule - a layer of ultra-thin high-density carbon containing the deuterium-tritium (DT) fusion fuel. In addition to increased yield, the experiments achieved unprecedented pressures, exceeding those found at the center of the Sun.

PNNL Technology Clears Way for Ethanol-Derived Jet Fuel

News Release RICHLAND, Wash. -- ASTM International recently revised ASTM D7566 Annex A5 -- the Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons -- to add ethanol as an approved feedstock for producing alcohol-to-jet synthetic paraffinic kerosene (ATJ-SPK). The revision of ASTM D7566 Annex A5 clears the way for increased adoption of sustainable aviation fuels because ethanol feedstocks can be made from so many different low-cost sources.

Experiments at Berkeley Lab Help Trace Interstellar Dust Back to Solar System's Formation

Experiments conducted at the Department of Energy's Lawrence Berkeley National Laboratory helped to confirm that samples of interplanetary particles - collected from Earth's upper atmosphere and believed to originate from comets - contain dust leftover from the initial formation of the solar system.

Designing a better superconductor with geometric frustration

Notre Dame study shows a magnet-controlled "switch" in superconductor configuration provides unprecedented flexibility in managing the location of vortex filaments, altering the properties of the superconductor.

Robust MOF Material Exhibits Selective, Fully Reversible and Repeatable Capture of Toxic Atmospheric Gas

Scientists have developed a metal-organic framework material offering selective, reversible and repeatable capture of nitrogen dioxide from ambient air. This could lead to cost-effective capture of greenhouse gases, to facilitate sequestration and help mitigate air pollution and global warming.

Diamond Dust Shimmering Around Distant Stars

Some of the tiniest diamonds in the universe - bits of crystalline carbon hundreds of thousands of times smaller than a grain of sand - have been detected swirling around three infant star systems in the Milky Way. These microscopic gemstones are neither rare nor precious; they are, however, exciting for astronomers who identified them as the source of a mysterious cosmic microwave "glow" emanating from several protoplanetary disks in our galaxy.


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Professor Emily Liu Receives $1.8 Million DoE Award for Solar Power Systems Research

Li (Emily) Liu, associate professor of nuclear engineering and engineering physics in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer Polytechnic Institute, has been selected by the U.S. Department of Energy Solar Energy Technologies Office (SETO) to receive a $1.8 million award to study high-temperature molten-salt properties and corrosion mechanisms.

Vasilis Fthenakis Receives IEEE's William R. Cherry Award

UPTON, NY; Vasilis Fthenakis, a Senior Scientist Emeritus at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and Founder and Director of the Center for Life Cycle Analysis at Columbia University, will receive the 2018 William R. Cherry Award from the Institute of Electrical & Electronics Engineers (IEEE).

New PPPL director Steve Cowley is honored with knighthood by Queen Elizabeth II

Steven Cowley, newly named director of the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) effective July 1, has received a knighthood from Queen Elizabeth "for services to science and the development of nuclear fusion."

UVA Darden Releases Policy Playbook Identifying Six Actions to Catalyze Clean-Tech Innovation

Moving the needle on climate change will require substantive and disruptive innovation across multiple industry sectors. Public and private investment focused on a few key areas could have a significant impact, according to a new policy playbook released by the Batten Institute for Entrepreneurship and Innovation on 8 June.

Work Begins on New SLAC Facility for Revolutionary Accelerator Science

The Department of Energy's SLAC National Accelerator Laboratory has started to assemble a new facility for revolutionary accelerator technologies that could make future accelerators 100 to 1,000 times smaller and boost their capabilities.

Oak Ridge National Laboratory Launches America's New Top Supercomputer for Science

The U.S. Department of Energy's Oak Ridge National Laboratory unveiled Summit as the world's most powerful and smartest scientific supercomputer.

Takeuchi Receives European Inventor Award 2018 in the Non-EPO Countries Category

Prolific patent-holder won for inventing battery that increases the lifespan of implantable defibrillators fivefold, greatly reducing need for reoccurring surgery

Steve Kevan Named Next Director of Berkeley Lab's Advanced Light Source

After an international search, Stephen D. "Steve" Kevan has been named the new director of the Advanced Light Source (ALS) at the U.S. Department of Energy's Lawrence Berkeley National Laboratory.

International corrosion society elects first Sandia fellow

Sandia National Laboratories materials scientist David Enos has been elected a fellow of NACE International, the chief professional society for corrosion engineering. He is the first Sandia employee to receive the honor.

Power to the People

The University of Utah College of Engineering has received a $2 million grant to create a laboratory and develop new technology for communities with backup power sources, known as microgrids, so they can quickly and more securely operate in the event of a massive power outage due to a natural disaster or cyberattack.


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Simulations of Magnetically Confined Plasmas Reveal a Self-Regulating Stabilizing Mechanism

A mysterious mechanism that prevents instabilities may be similar to the process that maintains the Earth's magnetic field.

Seeing All the Colors of the Plasma Wind

2-D velocity imaging helps fusion researchers understand the role of ion winds (aka flows) in the boundary of tokamak plasmas.

Renewable Solvents Derived From Lignin Lowers Waste in Biofuel Production

New class of solvents breaks down plant biomass into sugars for biofuels and bioproducts in a closed-loop biorefinery concept.

Scientists Studying Nuclear Spin Make a Surprising Discovery

The size of a nucleus appears to influence the direction of certain particles emitted from collisions with spinning protons.

Simulating Turbulent Bubbly Flows in Nuclear Reactors

With a better understanding of bubbly flows, researchers can improve the safety and operation of our nuclear reactors.

Solving a Magnesium Mystery in Rechargeable Battery Performance

Study reveals surprising, bad chemical reactivity in battery components previously considered compatible.

Changing the Surroundings Improves Catalysis

Water changes how cobalt-based molecule turns carbon dioxide into chemical feedstock.

How to Draw a Line Narrower Than a Cold Virus

Scientists use ion beams to write high-purity metal structures, enabling nanofabrication opportunities.

Powering Up With a Smart Window

Window material repeatedly switches from being see-through to blocking the heat and converting sunlight into electricity.

Remnant Superconductivity From Invisible Stripes

Scientists used an intense light to unveil hidden rivers that transport electricity with no loss.


Spotlight

Friday June 15, 2018, 10:00 AM

Professor Emily Liu Receives $1.8 Million DoE Award for Solar Power Systems Research

Rensselaer Polytechnic Institute (RPI)

Thursday June 07, 2018, 03:05 PM

Celebrating 40 years of empowerment in science

Argonne National Laboratory

Monday May 07, 2018, 10:30 AM

Introducing Graduate Students Across the Globe to Photon Science

Brookhaven National Laboratory

Wednesday May 02, 2018, 04:05 PM

Students from Massachusetts and Washington Win DOE's 28th National Science Bowl(r)

Department of Energy, Office of Science

Thursday April 12, 2018, 07:05 PM

The Race for Young Scientific Minds

Argonne National Laboratory

Wednesday March 14, 2018, 02:05 PM

Q&A: Al Ashley Reflects on His Efforts to Diversify SLAC and Beyond

SLAC National Accelerator Laboratory

Thursday February 15, 2018, 12:05 PM

Insights on Innovation in Energy, Humanitarian Aid Highlight UVA Darden's Net Impact Week

University of Virginia Darden School of Business

Friday February 09, 2018, 11:05 AM

Ivy League Graduate, Writer and Activist with Dyslexia Visits CSUCI to Reframe the Concept of Learning Disabilities

California State University, Channel Islands

Wednesday January 17, 2018, 12:05 PM

Photographer Adam Nadel Selected as Fermilab's New Artist-in-Residence for 2018

Fermi National Accelerator Laboratory (Fermilab)

Wednesday January 17, 2018, 12:05 PM

Fermilab Computing Partners with Argonne, Local Schools for Hour of Code

Fermi National Accelerator Laboratory (Fermilab)

Wednesday December 20, 2017, 01:05 PM

Q&A: Sam Webb Teaches X-Ray Science from a Remote Classroom

SLAC National Accelerator Laboratory

Monday December 18, 2017, 01:05 PM

The Future of Today's Electric Power Systems

Rensselaer Polytechnic Institute (RPI)

Monday December 18, 2017, 12:05 PM

Supporting the Development of Offshore Wind Power Plants

Rensselaer Polytechnic Institute (RPI)

Tuesday October 03, 2017, 01:05 PM

Stairway to Science

Argonne National Laboratory

Thursday September 28, 2017, 12:05 PM

After-School Energy Rush

Argonne National Laboratory

Thursday September 28, 2017, 10:05 AM

Bringing Diversity Into Computational Science Through Student Outreach

Brookhaven National Laboratory

Thursday September 21, 2017, 03:05 PM

From Science to Finance: SLAC Summer Interns Forge New Paths in STEM

SLAC National Accelerator Laboratory

Thursday September 07, 2017, 02:05 PM

Students Discuss 'Cosmic Opportunities' at 45th Annual SLAC Summer Institute

SLAC National Accelerator Laboratory

Thursday August 31, 2017, 05:05 PM

Binghamton University Opens $70 Million Smart Energy Building

Binghamton University, State University of New York

Wednesday August 23, 2017, 05:05 PM

Widening Horizons for High Schoolers with Code

Argonne National Laboratory

Saturday May 20, 2017, 12:05 PM

Rensselaer Polytechnic Institute Graduates Urged to Embrace Change at 211th Commencement

Rensselaer Polytechnic Institute (RPI)

Monday May 15, 2017, 01:05 PM

ORNL, University of Tennessee Launch New Doctoral Program in Data Science

Oak Ridge National Laboratory

Friday April 07, 2017, 11:05 AM

Champions in Science: Profile of Jonathan Kirzner

Department of Energy, Office of Science

Wednesday April 05, 2017, 12:05 PM

High-Schooler Solves College-Level Security Puzzle From Argonne, Sparks Interest in Career

Argonne National Laboratory

Tuesday March 28, 2017, 12:05 PM

Champions in Science: Profile of Jenica Jacobi

Department of Energy, Office of Science

Friday March 24, 2017, 10:40 AM

Great Neck South High School Wins Regional Science Bowl at Brookhaven Lab

Brookhaven National Laboratory

Wednesday February 15, 2017, 04:05 PM

Middle Schoolers Test Their Knowledge at Science Bowl Competition

Argonne National Laboratory

Friday January 27, 2017, 04:00 PM

Haslam Visits ORNL to Highlight State's Role in Discovering Tennessine

Oak Ridge National Laboratory

Tuesday November 08, 2016, 12:05 PM

Internship Program Helps Foster Development of Future Nuclear Scientists

Oak Ridge National Laboratory

Friday May 13, 2016, 04:05 PM

More Than 12,000 Explore Jefferson Lab During April 30 Open House

Thomas Jefferson National Accelerator Facility

Monday April 25, 2016, 05:05 PM

Giving Back to National Science Bowl

Ames Laboratory

Friday March 25, 2016, 12:05 PM

NMSU Undergrad Tackles 3D Particle Scattering Animations After Receiving JSA Research Assistantship

Thomas Jefferson National Accelerator Facility

Tuesday February 02, 2016, 10:05 AM

Shannon Greco: A Self-Described "STEM Education Zealot"

Princeton Plasma Physics Laboratory

Monday November 16, 2015, 04:05 PM

Rare Earths for Life: An 85th Birthday Visit with Mr. Rare Earth

Ames Laboratory

Tuesday October 20, 2015, 01:05 PM

Meet Robert Palomino: 'Give Everything a Shot!'

Brookhaven National Laboratory

Tuesday April 22, 2014, 11:30 AM

University of Utah Makes Solar Accessible

University of Utah

Wednesday March 06, 2013, 03:40 PM

Student Innovator at Rensselaer Polytechnic Institute Seeks Brighter, Smarter, and More Efficient LEDs

Rensselaer Polytechnic Institute (RPI)

Friday November 16, 2012, 10:00 AM

Texas Tech Energy Commerce Students, Community Light up Tent City

Texas Tech University

Wednesday November 23, 2011, 10:45 AM

Don't Get 'Frosted' Over Heating Your Home This Winter

Temple University

Wednesday July 06, 2011, 06:00 PM

New Research Center To Tackle Critical Challenges Related to Aircraft Design, Wind Energy, Smart Buildings

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Friday April 22, 2011, 09:00 AM

First Polymer Solar-Thermal Device Heats Home, Saves Money

Wake Forest University

Friday April 15, 2011, 12:25 PM

Like Superman, American University Will Get Its Energy from the Sun

American University

Thursday February 10, 2011, 05:00 PM

ARRA Grant to Help Fund Seminary Building Green Roof

University of Chicago

Tuesday December 07, 2010, 05:00 PM

UC San Diego Installing 2.8 Megawatt Fuel Cell to Anchor Energy Innovation Park

University of California San Diego

Monday November 01, 2010, 12:50 PM

Rensselaer Smart Lighting Engineering Research Center Announces First Deployment of New Technology on Campus

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Friday September 10, 2010, 12:40 PM

Ithaca College Will Host Regional Clean Energy Summit

Ithaca College

Tuesday July 27, 2010, 10:30 AM

Texas Governor Announces $8.4 Million Award to Create Renewable Energy Institute

Texas Tech University

Friday May 07, 2010, 04:20 PM

Creighton University to Offer New Alternative Energy Program

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