New research at the University of Illinois brings working artificial photosynthesis a step closer to reality.
The team has successfully produced fuel from water, carbon dioxide and visible light through artificial photosynthesis. Their method effectively converts carbon dioxide into longer, more complex molecules, such as propane. When fully developed, artificial photosynthesis of this kind can be used to store solar energy in chemical bonds (i.e., fuel) for peak load times.
"The goal here is to produce complex, liquefiable hydrocarbons from excess CO2 and other sustainable sources such as sunlight," said Prashant Jain, professor of chemistry and co-author of the study.
"Liquid fuels are ideal because they are easier, safer and more economical to transport than gas, and because they are made from molecules with long chains, they contain more stitches – which means that they pack energy closer."
Plants use photosynthesis to capture energy from sunlight in the form of glucose. Glucose is a relatively energy-rich compound (it is a sugar), so plants can use it effectively as a kind of chemical energy that they compile from (relatively low-energy) CO2. Researchers have long sought to recreate this process in the lab, with varying degrees of success, as it holds great promise for clean energy applications.
The new study reports on probably the most successful attempt at simulating photosynthesis to date. The artificial process that the team has developed is based on the same green light that stimulates photosynthesis in plants. It mixes CO2 and water in fuel with a little help from golden nanoparticles that serve as a catalyst. The electron-rich gold particles absorb green light and process the transfer of protons and electrons between water and CO2 – broadlyplay same role as the chlorophyll pigment in natural photosynthesis.
Golden nanoparticles work particularly well in this role, says Jain, because their surfaces interact with CO2 molecules in the right way. They are also quite efficient at absorbing light and do not break down or break down like other metals do.
While the resulting fuel can easily be burned to recover all that energy, it would not be the best approach, the team writes. By simply burning it, all the CO2 is released back into the atmosphere, what is countingin the first place a counterproductive effect on the harvesting and storage of solar energy, says Jain.
"There are other, more unconventional, potential uses of the hydrocarbons that have emerged from this process," he says.
"They can be used to power fuel cells to produce electrical power and voltage. There are laboratories around the world trying to figure out how to convert hydrocarbons to electricity efficiently."
As exciting as the development is, the team recognizes that their artificial photosynthesis process is not nearly as efficient as in plants.
"We need to learn how to adjust the catalyst to increase the efficiency of chemical reactions," he said.
"Then we can start with the hard work to determine how we can scale up the process. And like any unconventional energy technology, many economic feasibility questions will also be answered."
The paper "Plasmonic photosynthesis of C1-C3 hydrocarbons from carbon dioxide assisted by an ionic liquid" has been published in the journal Nature communication.