Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Device Uses Solar Energy to Convert Carbon Dioxide into Fuel

20.04.2007
Chemists at the University of California, San Diego have demonstrated the feasibility of exploiting sunlight to transform a greenhouse gas into a useful product.

Many Earth Week activities will draw attention to the increasing concentration of carbon dioxide in the atmosphere and the resulting impact on global climate. Now Clifford Kubiak, professor of chemistry and biochemistry, and his graduate student Aaron Sathrum have developed a prototype device that can capture energy from the sun, convert it to electrical energy and “split” carbon dioxide into carbon monoxide (CO) and oxygen.

Because their device is not yet optimized, they still need to input additional energy for the process to work. However, they hope that their results, which they presented at last month’s meeting of the American Chemical Society, will draw attention to the promise of the approach.

“For every mention of CO2 splitting, there are more than 100 articles on splitting water to produce hydrogen, yet CO2 splitting uses up more of what you want to put a dent into,” explained Kubiak. “It also produces CO, an important industrial chemical, which is normally produced from natural gas. So with CO2 splitting you can save fuel, produce a useful chemical and reduce a greenhouse gas.”

Although carbon monoxide is poisonous, it is highly sought after. Millions of pounds of it are used each year to manufacture chemicals including detergents and plastics. It can also be converted into liquid fuel.

“The technology to convert carbon monoxide into liquid fuel has been around a long time,” said Kubiak. “It was invented in Germany in the 1920s. The U.S. was very interested in the technology during the 1970s energy crisis, but when the energy crisis ended people lost interest. Now things have come full circle because rising fuel prices make it economically competitive to convert CO into fuel.”

The device designed by Kubiak and Sathrum to split carbon dioxide utilizes a semiconductor and two thin layers of catalysts. It splits carbon dioxide to generate carbon monoxide and oxygen in a three-step process. The first step is the capture of solar energy photons by the semiconductor. The second step is the conversion of optical energy into electrical energy by the semiconductor. The third step is the deployment of electrical energy to the catalysts. The catalysts convert carbon dioxide to carbon monoxide on one side of the device and to oxygen on the other side.

Because electrons are passed around in these reactions, a special type of catalyst that can convert electrical energy to chemical energy is required Researchers in Kubiak’s laboratory have created a large molecule with three nickel atoms at its heart that has proven to be an effective catalyst for this process.

Choosing the right semiconductor is also critical to making carbon dioxide splitting practical say the researchers. Semiconductors have bands of energy to which electrons are confined. Sunlight causes the electrons to leap from one band to the next creating an electrical energy potential The energy difference between the bands—the band gap—determines how much solar energy will be absorbed and how much electrical energy is generated.

Kubiak and Sathrum initially used a silicon semiconductor to test the merits of their device because silicon is well-studied. However, silicon absorbs in the infrared range and the researchers say it is “too wimpy” to supply enough energy. The conversion of sunlight by silicon supplied about half of the energy needed to split carbon dioxide, and the reaction worked if the researchers supplied the other half of the energy needed.

They are now building the device using a gallium-phosphide semiconductor. It has twice the band gap of silicon and absorbs more energetic visible light. Therefore, they predict that it will absorb the optimal amount of energy from the sun to drive the catalytic splitting of carbon dioxide.

“This project brings together many scientific puzzle pieces,” said Sathrum. “Quite a bit of work has been done on each piece, but it takes more science to mesh them all together. Bringing all the pieces together is the part of the problem we are focused on.”

The research is supported by the Department of Energy.

Sherry Seethaler | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Power and Electrical Engineering:

nachricht Fraunhofer ISE Supports Market Development of Solar Thermal Power Plants in the MENA Region
21.02.2018 | Fraunhofer-Institut für Solare Energiesysteme ISE

nachricht New tech for commercial Lithium-ion batteries finds they can be charged 5 times fast
20.02.2018 | University of Warwick

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>