Interface Opens the Way to Efficient Catalysts

Enzymes are essential for nearly all metabolic processes in cells that require catalysis. They can serve as the blueprint for the development of new, highly efficient synthetic catalysts inspired by nature. The physicists in Prof. Cinchetti’s group at TU Dortmund University are primarily interested in the novel properties that emerge at interfaces formed by organic molecules placed in contact with a transition metal surface. One example of organic molecules studied in the research group are the porphyrin complexes. Porphyrins are molecules. Porphyrins represent the most prominent example of tetrapyrrolic compounds and are engaged in essential processes that take part in vital processes such as photosynthesis or oxygen transport in the human circulatory system just to mention a couple of examples.

The research group has now succeeded in creating one such metal-organic interface through vapor deposition of nickel porphyrins on a copper surface. In the process, the nickel ions in the center of the molecule form a well-ordered lattice structure. Such a 2D network presents two essential advantages. Firstly, the nickel ions are full-fledged single-atom catalysts, thus promising particularly good performance. Secondly, the Ni ions arranged in the 2D array have identical chemical and physical properties leading to an evenly distribution of the catalytic properties across the surface.

Interface enables decomposition of nitric oxide

The researchers then tested the performance of the interface they had developed by exposing it to nitric oxide (NO). Nitric oxide is a toxic and polluting gas that is emitted by cars, trucks, and other vehicles. The data indicate that this interface enables, through a chemical reaction called the disproportionation reaction, the decomposition of three nitric oxide molecules into one nitrous oxide (N2O) and one nitrogen dioxide (NO2) molecule. The first of these is non-toxic and has applications in medicine as an anesthetic and pain reliever, and the latter is used predominantly in the production of fertilizer. In addition, the researchers were able to show that the nitrogen dioxide molecules initially remain anchored to the nickel network but can be removed by subsequent heating of the system.

„The system we developed represents an example of biomimetic interfaces with which natural processes can be modeled and better understood, so that further classes of two-dimensional catalysts with high efficiency and selectivity can be developed in the future“ says Dr. Giovanni Zamborlini, a scientific staff member in Prof. Mirko Cinchetti’s research group. These novel catalysts could find application in many different areas, since they are ubiquitous within the chemical industry.

This work is the result of an international cooperation between TU Dortmund University, the Jülich Research Center, the University of Trieste, the University of Erlangen-Nuremberg, and the University of Graz.

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