Researchers from Tel Aviv University (TAU) have succeeded in producing “green” hydrogen through the use of green electricity. The resulting hydrogen is produced without air pollution and with a high level of efficiency.

The new method was developed by doctoral student Itzhak Grinberg and Dr. Oren Ben-Zvi under the guidance of Professor Iftach Yacoby of the School of Plant Sciences and Food Security at TAU’s Faculty of Life Sciences and Professor Lihi Adler-Abramovich of TAU’s School of Dental Medicine and Center for Nanoscience and Nanotechnology. The research results were published on July 11, 2023, in the journal Carbon Energy.

Hydrogen is a necessary raw material for both agriculture and industry, but 95 percent of the hydrogen produced in the world today is “black” or “gray,” produced from coal or natural gas and emitting 9-12 tons of carbon dioxide for every ton of hydrogen.

“Hydrogen is very rare in the atmosphere,” explains Grinberg, “although it is produced by enzymes in microscopic organisms, which receive the energy for this from photosynthesis processes. In the lab, we ‘electrify’ those enzymes — an electrode provides the energy instead of the sun. The result is a particularly efficient process, with no demand for extreme conditions, that can utilize electricity from renewable sources such as solar panels or wind turbine. However, the enzyme ‘runs away’ from the electric charge, so it needs to be held in place through chemical treatment. We found a simple and efficient way to attach the enzyme to the electrode and utilize it.”

The researchers used a hydrogel to attach the enzyme to the electrode and were able to produce green hydrogen using a biocatalyst and with over 90 percent efficiency. Over 90 percent of the electrons introduced into the system were deposited in the hydrogen without any secondary processes.

“The material of the gel itself is known, but our innovation is to use it to produce hydrogen,” Professor Yacoby explains. “We soaked the electrode in the gel which contained hydrogenase, an enzyme for producing hydrogen. The gel holds the enzyme for a long time, even under the electric voltage, and makes it possible to produce hydrogen with great efficiency and at environmental conditions favorable to the enzyme  for example, in salt water — in contrast to electrolysis, which requires distilled water.”

“Another advantage is that the gel assembles itself — you put the material in water, and it settles into nanometric fibers that form the gel,” Professor Adler-Abramovich adds. “We demonstrated that these fibers are also able to stick the enzyme to the electrode. We tested the gel with two other enzymes in addition to the hydrogenase, and proved that it was able to attach different enzymes to the electrode.”

“Today, ‘green’ hydrogen is produced primarily through electrolysis, which requires precious and rare metals such as platinum along with water distillation, which makes the green hydrogen up to 15 times more expensive than the polluting ‘grey’ one,” Dr. Ben-Zvi concludes. “We hope that in the future it will be possible to employ our method commercially, to lower the costs, and to make the switch towards using green hydrogen in industry, agriculture, and as a clean energy source.”