Nav: Home

Harvesting clean hydrogen fuel through artificial photosynthesis

May 03, 2018

ANN ARBOR--A new, stable artificial photosynthesis device doubles the efficiency of harnessing sunlight to break apart both fresh and salt water, generating hydrogen that can then be used in fuel cells.

The device could also be reconfigured to turn carbon dioxide back into fuel.

Hydrogen is the cleanest-burning fuel, with water as its only emission. But hydrogen production is not always environmentally friendly. Conventional methods require natural gas or electrical power. The method advanced by the new device, called direct solar water splitting, only uses water and light from the sun.

"If we can directly store solar energy as a chemical fuel, like what nature does with photosynthesis, we could solve a fundamental challenge of renewable energy," said Zetian Mi, a professor of electrical and computer engineering at the University of Michigan who led the research while at McGill University in Montreal.

Faqrul Alam Chowdhury, a doctoral student in electrical and computer engineering at McGill, said the problem with solar cells is that they cannot store electricity without batteries, which have a high overall cost and limited life.

The device is made from the same widely used materials as solar cells and other electronics, including silicon and gallium nitride (often found in LEDs). With an industry-ready design that operates with just sunlight and seawater, the device paves the way for large-scale production of clean hydrogen fuel.

Previous direct solar water splitters have achieved a little more than 1 percent stable solar-to-hydrogen efficiency in fresh or saltwater. Other approaches suffer from the use of costly, inefficient or unstable materials, such as titanium dioxide, that also might involve adding highly acidic solutions to reach higher efficiencies.

Mi and his team, however, achieved more than 3 percent solar-to-hydrogen efficiency. To reach this stable efficiency, the team built a nano-sized cityscape of gallium nitride towers that generated an electric field. The gallium nitride turns light, or photons, into mobile electrons and positively charged vacancies called holes. These free charges split water molecules into hydrogen and oxygen.

"When this specially engineered wafer is hit by photons, the electric field helps separate photogenerated electrons and holes to drive the production of hydrogen and oxygen molecules efficiently," Chowdhury said.

At present, the silicon backing of the chip does not contribute to its function, but it could be doing more. The next step may be to use the silicon to help capture light and funnel charge carriers to the gallium nitride towers.

"Although the 3 percent efficiency might seem low, when put in the context of the 40 years of research on this process, it's actually a big breakthrough," Mi said. "Natural photosynthesis, depending how you calculate it, has an efficiency of about 0.6 percent."

He adds that 5 percent efficiency is the threshold for commercialization, but his team is aiming for 20 or 30 percent efficiency.

Mi conducts similar research to strip carbon dioxide of its oxygen to turn the resulting carbon into hydrocarbons, such as methanol and syngas. This research path could potentially remove carbon dioxide from the atmosphere, like plants do.

"That's the truly exciting part," Mi said.

The device is documented in the study, "A photochemical diode artificial photosynthesis system for unassisted high efficiency overall pure water splitting," published in Nature Communications. Along with Mi and Chowdhury, co-authors include Michel Trudeau of the Center of Excellence in Transportation Electrification and Energy Storage, Hydro-Québec, and Hong Guo of McGill University.
-end-
The work was supported by the Fuel Cell Technologies Office of the U.S. Department of Energy and Emissions Reduction Alberta.

University of Michigan

Related Solar Cells Articles:

Solar cells more efficient thanks to new material standing on edge
Researchers from Lund University in Sweden and from Fudan University in China have successfully designed a new structural organization using the promising solar cell material perovskite.
Printable solar cells just got a little closer
A University of Toronto Engineering innovation could make printing solar cells as easy and inexpensive as printing a newspaper.
A big nano boost for solar cells
Solar cells convert light into electricity. While the sun is one source of light, the burning of natural resources like oil and natural gas can also be harnessed.
Game changer for organic solar cells
Researchers develop a simple processing technique that could cut the cost of organic photovoltaics and wearable electronics.
Physics, photosynthesis and solar cells
A University of California, Riverside assistant professor has combined photosynthesis and physics to make a key discovery that could help make solar cells more efficient.
Throwing new light on printed organic solar cells
Researchers at the University of Surrey have achieved record power conversion efficiencies for large area organic solar cells.
A new way to image solar cells in 3-D
Berkeley Lab scientists have developed a way to use optical microscopy to map thin-film solar cells in 3-D as they absorb photons.
Toward 'greener,' inexpensive solar cells
Solar panels are proliferating across the globe to help reduce the world's dependency on fossil fuels.
A new technique opens up advanced solar cells
Using a novel spectroscopic technique, EPFL scientists have made a much-needed breakthrough in cutting-edge photovoltaics.
OU physicists developing new systems for next generation solar cells
University of Oklahoma physicists are developing novel technologies with the potential to impact utility-scale energy generation, increase global energy capacity and reduce dependence on fossil fuels by producing a new generation of high efficiency solar cells.

Related Solar Cells Reading:

PHYSICS OF SOLAR CELLS, THE (Properties of Semiconductor Materials)
by Jenny Nelson (Author)

Practical Photovoltaics: Electricity from Solar Cells, 3rd Edition
by Richard J. Komp (Author), John Perlin (Foreword)

Solar Cell Materials: Developing Technologies (Wiley Series in Materials for Electronic & Optoelectronic Applications)
by Arthur Willoughby (Author), Gavin J. Conibeer (Editor)

Build A Solar Hydrogen Fuel Cell System
by Phillip Hurley (Author)

Large-Scale PV Module Manufacturing Using Ultra-Thin Polycrystalline Silicon Solar Cells
by National Renewable Energy Laboratory (NR (Creator)

A Basic Research on The Dye-Sensitized Solar Cells (DSSC)
by Arini Nuran Binti Zulkifili (Author), Akira Fujiki (Author)

Physics of Solar Cells: From Basic Principles to Advanced Concepts (No Longer Used)
by Peter Würfel (Author), Uli Würfel (Author)

Flexible Solar Cells
by Mario Pagliaro (Author), Giovanni Palmisano (Author), Rosaria Ciriminna (Author)

The Physics of Solar Cells: Perovskites, Organics, and Photovoltaic Fundamentals
by Juan Bisquert (Author)

Principles of Solar Cells, LEDs and Related Devices: The Role of the PN Junction
by Adrian Kitai (Author)

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Approaching With Kindness
We often forget to say the words "thank you." But can those two words change how you — and those around you — look at the world? This hour, TED speakers on the power of gratitude and appreciation. Guests include author AJ Jacobs, author and former baseball player Mike Robbins, Dr. Laura Trice, Professor of Management Christine Porath, and former Danish politician Özlem Cekic.
Now Playing: Science for the People

#509 Anisogamy: The Beginning of Male and Female
This week we discuss how the sperm and egg came to be, and how a difference of reproductive interest has led to sexual conflict in bed bugs. We'll be speaking with Dr. Geoff Parker, an evolutionary biologist credited with developing a theory to explain the evolution of two sexes, about anisogamy, sexual reproduction through the fusion of two different gametes: the egg and the sperm. Then we'll speak with Dr. Roberto Pereira, research scientist in urban entomology at the University of Florida, about traumatic insemination in bed bugs.