27 April 2015

Photosynthesis without plants

A system for artificial photosynthesis has been created

Marina Astvatsaturyan, Echo of MoscowThe hybrid system of artificial photosynthesis, which was developed by scientists from the Lawrence Berkeley National Laboratory and the University of California at Berkeley (University of California, Berkeley) under the auspices of the U.S. Department of Energy, combines semiconductor chemistry with biotechnology.

Consisting of semiconductor nanowires and bacteria, it, like plants in which the natural process of photosynthesis takes place, ensures the production of hydrocarbons due to solar energy.

Here and below are the drawings from the Berkeley Lab - VM press release.

An article about this (Nanowire-bacteria hybrids for unassisted solar carbon dioxide fixation to value-added chemicals – VM) was published in the journal Nano Letters by a group of authors led by a well-known nanotechnology chemist Peidong Yang from the Department of Materials Science at Berkeley Laboratory and Kavli Institute for Nanoscience in Energy (Kavli Energy NanoSciences Institute).

The combination of a set of biocompatible light-absorbing nanowires with a certain population of bacteria will make it possible to extract a double benefit for the environment, since it involves the chemical production of various compounds without the use of toxic substances, but with sunlight as an energy source, along with reducing carbon dioxide emissions into the atmosphere.

The system is based on the so-called "artificial forest" of nanowire heterostructures, which consist of silicon and titanium oxide. As Yan explains in a press release distributed by the Berkeley Laboratory (Major Advance in Artificial Photosynthesis Poses Win/Win for the Environment - VM), this "artificial forest" is similar to chloroplasts of green plants.

Under the influence of sunlight, electron-hole pairs arise in silicon and titanium oxide, absorbing in different parts of the light spectrum. Free electrons formed in silicon under the influence of photons of light pass to bacteria, where carbon dioxide is reduced, while holes – the so–called carriers of positive charge in semiconductors - formed in titanium oxide split water molecules to form free oxygen.

The forest of nanowires is seeded with bacteria that produce enzymes – catalysts for the reduction of carbon dioxide. The authors worked with the anaerobic bacterium Sporomusa ovata, which easily accepts electrons from the environment and uses them in carbon dioxide reduction reactions to acetic acid ether, which is an intermediate in the production of a variety of useful chemical compounds. After S.ovata has produced acetate, the genetically engineered E.coli bacterium begins to work in the system, synthesizing one or another target product from it, for example, butanol, which can serve as a substitute for gasoline.

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