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Device Uses Solar Energy to Convert Carbon Dioxide into Fuel
Sherry Seethaler, April 17, 2007 (UCSD Newscenter)

WHO
Chemists at the University of California, San Diego: Clifford Kubiak, professor of chemistry and biochemistry, graduate student Aaron Sathrum

WHAT
A prototype device using a semiconductor and two thin catalyst layers: Photons of sunlight are captured by the semiconductor, which converts them for solar energy into electrical energy. The electrified catalysts convert carbon dioxide into carbon monoxide on one side and oxygen on the other.

WHEN
Paper presented last month to the American Chemical Society. Prototype operational; practical applications still too far off to predict.

WHERE
UCSD at La Jolla, California.

WHY
- The researchers have created a special, three-atom nickel molecule to perform the special catalytic function. Bands of energy on a semiconductor have different energies. The sunlight causes the electrons to leap from one band to the next, releasing energy. Silicon was the first semiconductor used but the more advanced prototype uses a gallium-phosphide semiconductor with twice the band gap.
- Carbon monoxide is a valuable industrial substance, used in the manufacture of plastics and detergents, and can be converted into a liquid fuel.
- One small glitch: Right now the device requires more energy to work than it produces.

QUOTES
Kubiak: “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…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.”
Kubiak: “The technology to convert carbon monoxide into liquid fuel… was invented in Germany in the 1920s. The U.S. was very interested in the technology during the 1970s energy crisis…Now things have come full circle because rising fuel prices make it economically competitive…”