Researchers succeed in new enzyme system for hydrogen conversion

In Germany, a research team from the Technical University of Munich, the RUB, the Center national de la recherche scientifique Marseille and the Max Planck Institute for Chemical Energy Conversion in Mülheim an der Ruhr succeeded in incorporating the sensitive enzymes into a protective polymer in such a way that they can also be used for technical hydrogen conversion.

“If you embed the sensitive hydrogenases in suitable polymers, they work for several weeks even in the presence of oxygen,” says Nicolas Plumeré, Professor of Electrobiotechnology at the Technical University of Munich, formerly at the Ruhr University in Bochum. “Without this protection, they lose their activity within minutes.”

However, embedding in so-called redox polymers, plastics, whose side groups can transfer electrons, has a decisive disadvantage: They offer high resistance to the flow of electrons. In order to overcome it, one has to invest energy, and this is lost in the form of heat. The embedded hydrogenases completely lost their ability to generate hydrogen.

By cleverly choosing the polymer side groups, the research team has now succeeded in adjusting the redox potential of the polymer in such a way that they only need a low overvoltage to overcome the resistance.

Upon closer examination, the researchers found that the potential of the side groups had shifted slightly towards positive values as a result of the incorporation into the polymer matrix. In a further attempt, they therefore used a side group with a correspondingly negative potential. This trick brought the breakthrough: The hydrogenase was now able to catalyze the reaction again in both directions without loss of energy.