The system produced by University of Rochester scientists mimics photosynthesis, utilizing semiconductor nanocrystals for light absorbers and catalysts and germs to contribute electrons to the system. Bacteria (the large rods) engage with nanoparticle drivers (the small orange dots) to make hydrogen gas (H2, the bubbles).
Researchers at the University of Rochester are harnessing the power of germs and nanomaterials to mimic the process of photosynthesis and produce clean-burning hydrogen fuel.
As the global requirement for tidy, sustainable energy magnifies, researchers are drawing inspiration from the procedure of photosynthesis. Intending to design ingenious, environmentally friendly approaches for creating tidy hydrogen fuel, a research study team at the University of Rochester is starting a revolutionary task to mimic photosynthesis synthetically, using bacteria to send electrons to a nanocrystal semiconductor photocatalyst.
In a study recently published in the Proceedings of the National Academy of Sciences, Kara Bren, the Richard S. Eisenberg Professor in Chemistry at Rochester, and Todd Krauss, a professor of chemistry, reveal that the germs Shewanella oneidensis can act as a effective and economical source of electrons for their artificial photosynthesis system.
By leveraging the unique homes of these bacteria together with nanomaterials, the system has the possible to change present techniques that derive hydrogen from nonrenewable fuel sources, transforming the way hydrogen fuel is produced and opening an effective source of renewable resource.
” Hydrogen is certainly a fuel of high interest for the DOE today,” Bren states. “If we can figure out a method to effectively draw out hydrogen from water, this could lead to an extraordinary quantity of growth in tidy energy.”
A perfect fuel
Hydrogen is “a perfect fuel,” Bren says, “since its eco-friendly and a carbon-free alternative to fossil fuels.”
Unlike fossil fuels, which produce greenhouse gases and other pollutants, when hydrogen is burned, the only by-product is water vapor. Hydrogen fuel likewise has a high energy density, which indicates it consists of a lot of energy per unit of weight.
The challenges of utilizing hydrogen
In spite of hydrogens abundance, there is practically no pure hydrogen in the world; it is generally bound to other aspects, such as carbon or oxygen, in substances like hydrocarbons and water. To use hydrogen as a fuel source, it needs to be extracted from these compounds.
Researchers have traditionally drawn out hydrogen either from fossil fuels, or, more just recently, from water. To achieve the latter, there is a significant push to utilize synthetic photosynthesis.
During natural photosynthesis, plants absorb sunlight, which they utilize to power chain reaction to transform co2 and water into glucose and oxygen. In essence, light energy is converted into chemical energy that fuels the organism.
Synthetic photosynthesis is a procedure of transforming a plentiful feedstock and sunshine into a chemical fuel. Systems that simulate photosynthesis need three parts: a light absorber, a catalyst to make the fuel, and a source of electrons. These systems are typically submerged in water, and a light source supplies energy to the light absorber. The energy allows the catalyst to combine the provided electrons together with protons from the surrounding water to produce hydrogen gas.
The majority of the current systems, however, rely on fossil fuels during the production process or do not have an efficient way to transfer electrons.
” The method hydrogen fuel is produced now efficiently makes it a nonrenewable fuel source,” Bren states. “We wish to get hydrogen from water in a light-driven response so we have a really tidy fuel– and do so in such a way that we do not use nonrenewable fuel sources while doing so.”
Rochesters unique system
Krausss group and Brens group have been working for about a years to develop an efficient system that employs artificial photosynthesis and makes use of semiconductor nanocrystals for light absorbers and drivers.
One obstacle the scientists faced was finding out a source of electrons and effectively transferring the electrons from the electron donor to the nanocrystals. Other systems have used ascorbic acid, typically referred to as vitamin C, to provide electrons back to the system. While vitamin C might appear affordable, “you need a source of electrons that is practically totally free or the system becomes too pricey,” Krauss says.
In their paper, Krauss and Bren report on an unlikely electron donor: germs. They discovered that Shewanella oneidensis, germs very first collected from Lake Oneida in upstate New York, provides a successfully free, yet effective, way to supply electrons to their system.
While other laboratories have integrated bacteria and nanostructures, “all of those efforts are taking electrons from the nanocrystals and putting them into the germs, then utilizing the bacterial equipment to prepare fuels,” Bren states. “As far as we know, ours is the first case to go the opposite way and use the bacteria as an electron source to a nanocrystal catalyst.”
When germs grow under anaerobic conditions– conditions without oxygen– they respire cellular compounds as fuel, releasing electrons in the process. Shewanella oneidensis can take electrons produced by its own internal metabolism and donate them to the external driver.
A fuel of the future
Bren envisions that, in the future, individual homes might potentially have vats and underground tanks to harness the power of the sun to produce and keep small batches of hydrogen, allowing people to power their homes and cars with low-cost, clean-burning fuel. Bren keeps in mind there are presently buses, cars and trucks, and trains powered by hydrogen fuel cells however almost all the hydrogen that is available to power these systems comes from fossil fuels.
” The innovations out there,” she states, “but till the hydrogens coming from water in a light-driven response– without utilizing nonrenewable fuel sources– it isnt really assisting the environment.”
Reference: “Shewanella oneidensis MR-1 respires CdSe quantum dots for photocatalytic hydrogen evolution” by Emily H. Edwards, Jana Jelušić, Ryan M. Kosko, Kevin P. McClelland, Soraya S. Ngarnim, Wesley Chiang, Sanela Lampa-Pastirk, Todd D. Krauss and Kara L. Bren, 17 April 2023, Proceedings of the National Academy of Sciences.DOI: 10.1073/ pnas.2206975120.
The study was moneyed by the United States Department of Energy.
Unlike fossil fuels, which produce greenhouse gases and other pollutants, when hydrogen is burned, the only by-product is water vapor. Hydrogen fuel also has a high energy density, which indicates it consists of a lot of energy per unit of weight. It can be utilized in a variety of applications, including fuel cells, and can be made on both big and little scales, making it possible for whatever from home usage to commercial production.
Artificial photosynthesis is a procedure of converting an abundant feedstock and sunlight into a chemical fuel. Systems that mimic photosynthesis need three components: a light absorber, a catalyst to make the fuel, and a source of electrons.
