Bionic Leaf

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A diagram of how the Bionic Leaf works

The Bionic Leaf is a system that uses solar energy to split water molecules and hydrogen-eating bacteria to produce liquid fuels. It is made of a thin sheet of semiconducting silicon with different catalytic materials bonded to its two sides. A layer of bacteria with a cobalt-based catalyst is bonded to the silicon, which splits water into oxygen and hydrogen. The bionic leaf's artificial photosynthesis is two times better than natural photosynthesis.[1]

The water-splitting electrodes produce hydrogen, which is consumed by the bacteria to synthesize biomass and fuels or chemical products.

History[edit]

The artificial leaf was a development from Daniel Nocera’s lab, where they developed an anode electrocatalyst for the oxidation of water, capable of splitting water into hydrogen and oxygen gases.[2] Catalysts cobalt phosphate and nickel-molybdenum-zinc were bonded to the silicon to spur the creation of oxygen and hydrogen, respectively.

The Silver Lab[3] of Harvard Medical School joined Nocera’s team to build the Bionic Leaf. It merged the artificial leaf with genetically engineered bacteria that feed on the hydrogen and convert CO2 in the air into alcohol fuels or chemicals. The first model that used the nickel-molybdenum-zinc alloy created a reactive oxygen species that destroyed the bacteria's DNA. Abnormally high voltages were used to prevent the microbes from dying, but it also resulted in reduced efficiency.[4]

An improved model removed the nickel-molybdenum-zinc alloy catalyst and allowed the team to reduce the voltage. The new catalyst improved the efficiency of producing alcohol fuels by nearly 10 percent.[5]

Applications[edit]

Agriculture[edit]

The soil bacterium Xanthobacter autotrophicus was used to consume hydrogen generated by the water-splitting reaction and take nitrogen from the atmosphere to produce ammonia and phosphorus.[6] These products can be used as fertilizers. In greenhouse experiments at the Arnold Arboretum, growing radishes with X. autorophicus resulted in an increase in size without added fertilizer. The bacteria can secrete ammonia directly, which can appeal to companies that convert atmospheric nitrogen into ammonia, which relies heavily on fossil fuels.[7]

Bioplastics[edit]

Researchers were able to expand the portfolio of the system able to produce isobutanol and isopentanol. Sinskey's lab at MIT[8] engineered a Ralstonia strain to use in the bionic leaf to generate polyhydroxybutyrate PHB, a bio-plastic precursor.[9]

Atmosphere[edit]

Carbon dioxide, a greenhouse gas, traps heat in the atmosphere. The bionic leaf can potentially be used to consume carbon dioxide. The bionic leaf can eliminate 180 grams of carbon dioxide out of 230,000 litres of air for each kilowatt hour of energy it consumes.[10][11]

Other applications[edit]

References[edit]

  1. ^ "Harvard Researchers Pioneer Photosynthetic Bionic Leaf | News | The Harvard Crimson". www.thecrimson.com. Retrieved 2019-04-13.
  2. ^ Nocera, Daniel G. (2012-05-15). "The Artificial Leaf". Accounts of Chemical Research. 45 (5): 767–776. doi:10.1021/ar2003013. ISSN 0001-4842. PMID 22475039.
  3. ^ "Pamela Silver Laboratory | Harvard Medical School Department of Systems Biology". Retrieved 2019-05-09.
  4. ^ Nangle, Shannon N; Sakimoto, Kelsey K; Silver, Pamela A; Nocera, Daniel G (December 2017). "Biological-inorganic hybrid systems as a generalized platform for chemical production". Current Opinion in Chemical Biology. 41: 107–113. doi:10.1016/j.cbpa.2017.10.023. PMID 29136557.
  5. ^ Burke, Ed. "Turning CO2 & Sunshine into Fuel: The Bionic Leaf". www.burkeoil.com. Retrieved 2019-04-13.
  6. ^ "Harvard's bionic leaf could help feed the world". Harvard Gazette. 2018-01-31. Retrieved 2019-04-13.
  7. ^ Liu, Chong; Sakimoto, Kelsey K.; Colón, Brendan C.; Silver, Pamela A.; Nocera, Daniel G. (2017-06-20). "Ambient nitrogen reduction cycle using a hybrid inorganic–biological system". Proceedings of the National Academy of Sciences. 114 (25): 6450–6455. doi:10.1073/pnas.1706371114. ISSN 0027-8424. PMC 5488957. PMID 28588143.
  8. ^ "Sinskey Lab Home | Sinskey Lab". sinskeylab.mit.edu. Retrieved 2019-05-09.
  9. ^ Grousseau, Estelle; Lu, Jingnan; Gorret, Nathalie; Guillouet, Stéphane E.; Sinskey, Anthony J. (2014-05-01). "Isopropanol production with engineered Cupriavidus necator as bioproduction platform" (PDF). Applied Microbiology and Biotechnology. 98 (9): 4277–4290. doi:10.1007/s00253-014-5591-0. ISSN 1432-0614. PMID 24604499.
  10. ^ Liu, Chong; Nangle, Shannon N.; Colón, Brendan C.; Silver, Pamela A.; Nocera, Daniel G. (2017). "13 C-Labeling the carbon-fixation pathway of a highly efficient artificial photosynthetic system". Faraday Discussions. 198: 529–537. Bibcode:2017FaDi..198..529L. doi:10.1039/C6FD00231E. ISSN 1359-6640. PMID 28294218.
  11. ^ "'Bionic Leaf' Could One Day Help Reduce CO2 In The Atmosphere". www.wbur.org. Retrieved 2019-04-13.