Harvard University uses bacteria to convert solar energy into liquid fuel

The collection of sunlight is the ability of the plant to master it more than one billion years ago. It uses solar energy to feed itself through the photosynthesis of the surrounding air and water. Scientists also figured out how to use solar power to generate hydrogen from photovoltaic cells to later used fuel cells. However, hydrogen has not been used as a kind of vehicle fuel that is practical in the world, or it can be used to generate electricity for liquid fuels.

According to reports recently organized by the Physicist Organization Network, the Harvard College of Art and Science, Harvard Medical School and the Weiss Bioengineering Institute were inspired by the leaves to create an “artificial leaf” system that uses bacteria to convert solar energy into liquid fuel. Using catalysts to make sunlight decompose water into hydrogen and oxygen, a bacteria was designed to convert hydrogen dioxide into liquid fuel isopropanol. The study was published in the "Journal of the National Academy of Sciences".

The paper's senior author, Pamela Hillway, Elliot T and Adams, of the Department of Biochemistry and Systems Biology at Harvard Medical School, called the system a bionic leaf, promising to invent this artificial leaf. The work of Harvard professor Patterson Wood and Daniel Nocera.

Two years ago, Nocera was engaged in research at the Department of Chemistry at the Massachusetts Institute of Technology. He once pointed out that the idea of ​​artificial leaves comes from the imagination of chemists in the early years, and one day they will find "the secrets that plants guard." Nosella said that the most important secret is the process by which water breaks down into hydrogen and oxygen. A solar collector is sandwiched between thin films of hydrogen and oxygen generated on both sides of artificial leaves. When artificial leaves are placed in water under sunlight, bubbles form around the artificial leaves, and the released hydrogen can be used to generate electricity for the fuel cell. These self-sufficient cheap energy supply units are attractive to remote areas and developing countries that need electricity, but the designs so far have relied on expensive metals such as platinum and high-cost manufacturing processes.

In order to make these devices more widely used, Nocera will replace the platinum catalyst used to produce hydrogen with nickel molybdenum-zinc alloys. On the other side of the leaf, there is a thin film of cobalt used to produce oxygen. Nocera pointed out that all these materials are very rich on the earth, unlike rare and expensive metal platinum, precious metal oxides and semiconductor materials that have been used by others. He said: “Solar-powered studies such as artificial leaves for poverty-stricken areas provide the most direct path to the future of global sustainable energy development.”

Shortly afterwards, Nocera came to Harvard from the Massachusetts Institute of Technology and began collaborating with Hillway. They agreed on the concept of “individualized energy” or the localization of manufacturing energy and believed that energy localization will be attractive in developing countries. This is relative to the current energy system, such as the way that oil needs to be produced centrally and then sent to the gas station.

Hillway said: "We do not want to create some super-complex systems, on the contrary, are looking for more simple and easy to use." And this artificial leaf is cheap, the catalyst is also very easy to obtain.

Heilway said: “The growth conditions of the catalysts and organisms such as bacteria produced are extremely suitable and matched.” In the new system, once the bionic leaves produce oxygen and hydrogen, hydrogen will be “fed” to a true oxygen. Alkali-producing bacteria. One enzyme in the bacteria reduces hydrogen into protons and electrons, and binds them to carbon dioxide to replicate more cells. Then, the researchers used new methods to make isopropanol. Based on an earlier discovery by Anthony Hinske, a professor of microbiology and health sciences and technology at MIT, the new method is the bacteria that produces isopropanol through a metabolic process.

Sylve, one of the core professors of the Wise Institute of Biological Engineering, said: “Now new research has proven a concept that you can have a way to collect solar energy and store it in the form of liquid fuels. A powerful catalyst has brought it to fruition. What we originally thought was to use several types of bacteria and collected solar energy to complete this task. Now it can be done with a single kind of bacteria. This is a perfect match."

“The advantage of inorganic catalysts and bio-interfaces is that you have an unprecedented platform. This is the paper from solar energy to chemical products,” said Brendan, a co-author of the paper and a biological system researcher at the Hillway Laboratory. At the heart of the matter, so far we have been using plants, but now we are developing unprecedented biological capabilities to make large quantities of compounds." Researchers believe that the same principles can be used to produce drugs such as small amounts of vitamins.

The top priority of this research team is to improve the ability of bionic blades to convert solar energy into biomass by optimizing catalysts and bacteria. Their goal is to achieve 5% efficiency compared to the photosynthesis efficiency that converts sunlight into biomass by 1%. (Reporter Hualing)