The chemical reactions of photosynthesis require more energy than can be imparted by visible light to single electrons. Chinese scientists have developed a nanotech solution to harvest energy from multiple electrons—something alternative approaches to artificial photosynthesis have not yet managed to do. From Colin Barras at NewScientist.com news service “Nanotubes bring artificial photosynthesis a step nearer“:
Carbon nanotubes are the crucial chemical ingredient that could make artificial photosynthesis possible, say a team of Chinese researchers. The team has found that nanotubes mimic an important step in photosynthesis that chemists have been unable to copy until now.
Artificial photosynthesis has the potential to efficiently produce hydrogen that could be used as a clean fuel for vehicles. It could also be used to mop up carbon dioxide from the atmosphere.
Photosynthetic organisms use the energy from light to break down water into oxygen and hydrogen. The hydrogen then reacts with carbon dioxide to help synthesise carbohydrates, the molecules organisms use to store energy.
Chemists have long tried in vain to reproduce the process, but one key step in particular has proven impossible to copy.
Visible photons can only contribute a limited amount of energy towards a chemical reaction. This energy is absorbed by electrons involved in the reaction.
Reactions that require more energy, such as the synthesis of carbohydrates, can only proceed when several energised electrons are available to contribute. For that reason, chemists say the photosynthesis falls into a class of reactions known as multiple electron systems.
But nobody has succeeded in making artificial multiple electron systems that could provide the necessary energy for artificial photosynthesis.
…Now, a team led by Xian-Fu Zhang at the Hebei Normal University of Science and Technology in Qinhuangdao, China, has found that single-walled carbon nanotubes could act as the chemical heart of a multiple electron system.
The research was published in the journal ChemPhysChem (citation).
—Jim
