Joachim Rode

He Focuses on a Small Cell of Great Importance

Tuesday 21 Sep 21
by Marianne Vang Ryde


Søren Bredmose Simonsen
Senior Researcher
DTU Energy
+45 20 12 06 11

What is an electrolytic cell?

An electrolytic cell uses electricity to split water molecules (H2O) into hydrogen (H2) and oxygen (O2), for example. This converts the electrical energy into chemical energy bound in the hydrogen molecules.

The cell consists of three layers: an anode and a cathode separated by an electrolyte. The electrolyte consists of a substance that does not allow gas molecules to pass, but only very specific ions (i.e. atoms with a surplus or deficit of electrons). A Solid Oxide Electrolysis Cell (SOEC) operates at high temperature (700-1,000 °C) and thus has very high efficiency. The two electrolysis products hydrogen and oxygen are formed on each side of the cell.

The hydrogen can be stored and then be reconverted into electricity in a fuel cell when needed. But you can also electrolyse carbon dioxide (CO2) into carbon monoxide (CO) using an SOEC cell. If you do it together with water, you get a mixture of hydrogen and CO as a product. This mixture is called synthesis gas, and it forms the base for a large number of syntheses of hydrocarbons that can be refined into liquid transport fuels.

Read more about soap bubbles on the website, which has been constructed by a small association of soap bubble enthusiasts, of which Søren Bredmose Simonsen is a member.

Søren Bredmose Simonsen took a Bachelor’s degree in philosophy before immersing himself in physics studies. This led him to work with catalysis, and he is now developing a new method for studying electrolytic cells closely. Cells that play an important role in the green transition. In addition, he knows everything about soap bubbles.

Around the world, researchers are working flat out to get electrolysis to function on a large scale. With electrolytic cells, you can make sustainable fuels using electricity from wind turbines or solar cells; so-called Power-to-X. Senior Researcher Søren Bredmose Simonsen goes the other way by focusing on the smallest conceivable scale to study what happens inside an electrolytic cell while it is running. For—like everything else—the cells wear out during use; they degrade. However, the question is how this happens and whether it may be possible to get them to last longer by changing the conditions or the way they run.

"I’ve always thought it interesting to examine whether we can have qualified views. All views are equally welcome, but are they also equally correct? "
Søren Bredmose Simonsen, Senior Researcher, DTU Energi

So far, the process has been studied by taking small pieces of degraded cells, studying them closely in an electron microscope, and then analysing what went wrong. But Søren Bredmose Simonsen will take one step further and study the cells while they are operating. And one year ago, he received an ERC Starting Grant of EUR 1.5 million from the European Research Council to develop his idea.

Handmade nanocells

You cannot simply put an electrolytic cell under an electron microscope, switch it on, and see what happens. The cell must first and foremost be incredibly small and thin for the electrons from the microscope to penetrate it. Normal cells are half a millimetre thick, but here they must not have a thickness of more than 100 nanometres, that is one thousandth of a hair’s breadth.

Søren and his team are themselves constructing the incredibly small cells in a clean and dust-free vacuum chamber. Using a laser, they shoot atoms onto a substrate, giving the cell the necessary three layers: an electrolyte—through which only ions can be passed—surrounded by two electrodes for handling hydrogen and oxygen, respectively. The cell is attached to a small chip with a heating element that can heat it up to 800 degrees—and, finally, it is provided with electrodes so that electricity can be passed through it.

Great demands are made on the cells. Just as importantly, however, is having access to a so-called Environmental Transmission Electron Microscope (E-TEM), which makes it possible to examine materials right down to the atomic level, while there is a reactive gas present, for example the water vapour that the electrolytic cell is to split into hydrogen and oxygen.

The advanced equipment is available in DTU Nanolab, and Søren is an expert in using it.

Physicist with philosophical ulterior motives

This was not on the cards based on his academic background. In fact, he started somewhere else completely—studying philosophy—one reason being that he was concerned with whether there is an objective truth.

“I’ve always thought it interesting to examine whether we can have qualified views. All views are equally welcome, but are they also equally correct? Are there good arguments or just arguments? These were among the questions to which I would try to find answers,” says Søren.

After taking his Bachelor’s degree, he continued his studies with physics, a discipline in which the truth may be easier to see. At any rate, one can usually agree on what an objective measurement is. His choice of studying precisely the truth about the effect of electrolytic cells must be said to depend on a coincidence.

As he approached the time at which he was to write his MSc thesis in physics, he wanted to work with something that could be used outside the university. He wrote to several companies asking whether they had a project he could immerse himself in, and Haldor Topsøe, which works with catalysis and process technology, including electrolysis, had.

“They wanted me to do a project on electron microscopy. I didn’t know anything about that at all, but they didn’t expect me to either,” says Søren somewhat surprisingly.

He also learnt quickly and ended up becoming so interested in the work that he continued with an industrial PhD with the same company. The way was thus paved for a researcher position instead of the career as an upper secondary school teacher that he had originally envisaged.

Soap bubbles with physics, geometry, and mathematics

However, he has not completely shelved the dissemination of knowledge. As a DTU researcher, he obviously teaches, but he can also be booked to give a lecture on soap bubbles. He is, in fact, an expert on them, and he has written a book about soap bubbles for Experimentarium. He knows many spectacular tricks, but he prefers above all to tell stories about the bubbles and their shapes, colours, and physics.

“For example, I did a presentation on soap bubbles and architecture at a meeting at the Danish Architecture Centre. There are actually a number of buildings that are inspired by the shapes of soap bubbles, including the Arch of Triumph by Spreckelsen in Paris. Fold a cube in steel wire and dip it in soapy water one and a half times, and you have the shape,” he says.

Most people have probably experienced soap bubbles as something very fragile. Søren can also disclose that their films are so thin that it takes 100 on top of each other before they have the same thickness as a piece of paper. This is roughly equal to the size of the nano-electrolytic cells he works with on a daily basis. However, the cells can never be included in a show; as they cannot be seen or handled outside the laboratory. But both parts can be described with physical and mathematical concepts, and that is exactly what Søren likes to do.

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