Tel Aviv University researchers have achieved a groundbreaking milestone by successfully producing highly efficient and low-cost green H₂. By harnessing the power of green electricity and utilizing a highly efficient biocatalyst, this innovative process generates H₂ without any air pollution.

H₂ plays a vital role as raw material in both agriculture and industry. However, most of the H₂ produced globally, approximately 95%, falls in the black or gray category. These types of H₂ are derived from coal or natural gas, emitting a significant 9 t–12 t of CO₂ for every ton of H₂ produced.

The new method was developed by doctoral student Itzhak Grinberg and Dr. Oren Ben-Zvi, under the guidance of Prof. Iftach Yacoby of the School of Plant Sciences and Food Security at the Faculty of Life Sciences and Prof. Lihi Adler-Abramovich of the School of Dental Medicine and the Center for Nanoscience and Nanotechnology. The promising research results were published in the prominent journal Carbon Energy, focusing on advanced materials and technology for clean energy and CO₂ emission reduction.

“H₂ is very rare in the atmosphere,” explained Itzhak 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, that is, 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 (a water-based gel) to attach the enzyme to the electrode and were able to produce green H₂ using a biocatalyst, and with over 90% efficiency; that is, over 90% of the electrons introduced into the system were deposited in the H₂ without any secondary processes.

“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 H₂ in industry, agriculture, and as a clean energy source,” said Dr. Oren Ben-Zvi

Prof. Iftach Yacoby said, “The material of the gel itself is known, but our innovation is to use it to produce H₂. We soaked the electrode in the gel, which contained an enzyme for producing H₂, called H2ase. The gel holds the enzyme for a long time, even under the electric voltage, and makes it possible to produce H₂ with great efficiency and at environmental conditions favorable to the enzyme — for example, in salt water, in contrast to electrolysis, which requires distilled water.

Prof. Lihi Adler-Abramovich said, “Another advantage is that the gel assembles itself—you put the material in water, and it settles into nanometric fibers that form the gel. 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 H2ase, and proved that it was able to attach different enzymes to the electrode.”

“Today, green H₂ is produced primarily through electrolysis, which requires precious and rare metals such as platinum along with water distillation, which makes the green H₂ up to 15 times more expensive than the polluting gray one,” said Dr. Oren Ben-Zvi. “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 H₂ in industry, agriculture, and as a clean energy source.”