Wednesday, April 18, 2007

Carbon Dioxide Conversion Idea

via ScienceDaily. I was going to wait until tomorrow to post this, but decided to close out the day with something a bit more positive.

Two researchers at the U of Cal-San Diego have developed a solar powered device that splits carbon dioxide into carbon monoxide and oxygen. CO is used in several industrial processes and could be an alternative energy source itself, being capable of being converted into a liquid fuel source. While the device currently needs additional energy inputs to complete the process, the technique show a great deal of promise.

"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. "

The crimp in the current process researched is the use of silicon as the semiconductive material. Silicon, which absorbs infrared light, has been used in the past experiments due to the substance's properties being well understood, but the energy provided by the electrons jumping to higher energy bands in the second step of the process isn't enough right now to complete the molecule splitting process, but only around half that needed. It is thought that the use of another semiconductive material, gallium-phosphide, might turn the trick. It has twice the electron band energy potential of silicon and is able to absorb light from the more energetic visible light spectrum, which the researchers believe could solve the dilemna.

What will they think of next?

No comments: