Scientific American – The notion of an artificial leaf makes so much sense. Leaves, of course, harness energy from the sun to turn carbon dioxide into the carbohydrates that power a plant’s cellular activities. For decades, scientists have been working to devise a process similar to photosynthesis to generate a fuel that could be stored for later. This could solve a major challenge of solar and wind power—providing a way to stow the energy when the sun is not shining and the air is still.
Many, many investigators have contributed over the years to the development of a form of artificial photosynthesis in which sunlight-activated catalysts split water molecules to yield oxygen and hydrogen—the latter being a valuable chemical for a wide range of sustainable technologies. A step closer to actual photosynthesis would be to employ this hydrogen in a reduction reaction that converts CO2 into hydrocarbons. Like a real leaf, this system would use only CO2, water and sunlight to produce fuels. The achievement could be revolutionary, enabling creation of a closed system in which carbon dioxide emitted by combustion was transformed back into fuel instead of adding to the greenhouse gases in the atmosphere.
Several researchers are pursuing this goal. Recently, one group has demonstrated that it is possible to combine water splitting and CO2 conversion into fuels in one system with high efficiency. In a June 2016 issue of Science, Daniel G. Nocera and Pamela A. Silver, both at Harvard University, and their colleagues reported on an approach to making liquid fuel (specifically fusel alcohols) that far exceeds a natural leaf’s conversion of carbon dioxide to carbohydrates. A plant uses just 1 percent of the energy it receives from the sun to make glucose, whereas the artificial system achieved roughly 10 percent efficiency in converting carbon dioxide to fuel, the equivalent of pulling 180 grams of carbon dioxide from the air per kilowatt-hour of electricity generated.
Read more at Scientific American.