All this talk about solar power and the weird thing is, plants have been doing it since the beginning of, well, plants. For years now, scientists have been trying to duplicate and improve upon the process of photosynthesis (even Jimmy Stewart tried it once.) And now a research group led by Osamu Ishitani has created a new catalyst that could turn CO2 into fuel efficiently, with only the power of the sun.
The new catalyst uses ruthenium and rhenium, two elements not found in your average leaf. But they do allow for the same first step (CO2 to CO) that plants use. In fact, it's considerably more efficient and simpler than the way plants do things.
CO is far more reactive than CO2, and so it's fairly simple to do a little bit of old-school organic chemistry to turn CO into burnable hydrocarbons like ethanol.
The trick was using the Ru catalyst to absorb the light, which it does very efficiently in the visual light spectrum, but then using the Re catalyst to actually take the electron produced and knock one of the oxygens off of the CO2. The Re complex has a quantum efficiency of 0.62, which means it actually uses 62% of the electrons it gets from the Ru catalyst to reduce the CO2. This number is extremely high.
The Ru-Re combination also excels at selecting CO2 over H2O. One big problem with artificial photosynthesis in the past is that these photocatalysts would often reduce water to OH just as easily as they reduced CO2 to CO. That waste of energy forced people to look into ways of scrubbing the CO2 of water (not a simple task.) But with this new catalyst, water isn't a problem.
Now, the only problem is to make sure the catalyst is stable and doesn't degrade over time. If they can do that, then there won't be much between this research and a CO2 to fuel manufacturing plant.
written by Carol, January 15, 2009
written by Carbon Bob, May 22, 2009
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