Researchers at the University of California, Berkeley, say that by combining nanoscale materials with bacteria, they have opened the door to a new way of designing systems that could efficiently turn carbon dioxide, water, and sunlight into useful organic compounds—similar to what plants do through photosynthesis. Down the road, they say, the system could become a commercially viable way to produce high-value chemicals like drug precursors used by the pharmaceutical industry, or to store renewable energy in the form of liquid fuels.
The goal of highly efficient artificial photosynthesis is a long-standing one, and there are many approaches to the problem, all of which face scientific hurdles (See “Sun + Water = Fuel” and “A Greener ‘Artificial Leaf’”). One general approach is to rely on microörganisms called electrotrophs, which can be coaxed, through the application of electricity, to make certain chemical building blocks.
The new system is the first one in which semiconductors, which are capable of both capturing solar energy and transmitting electricity to the microbes, have been directly combined with bacteria, says Peidong Yang, a professor of chemistry and materials science at the University of California, Berkeley, and an inventor of the system. Previous similar systems have relied on bulky solar panels to provide renewable electricity (see “Making Diesel from CO2 and Sunlight”). In this case, semiconducting nanowires capture energy from sunlight and pass electrons to electrotrophic bacteria, which are nestled within the wires. The electrotrophs use the electrons to turn carbon dioxide and water into useful chemical building blocks. Those are then passed to genetically engineered E. coli, which in turn make a wide range of products.
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