A robust catalyst

The energy transition is at risk of becoming a failure if hydrogen cannot be produced in a sustainable manner. Catalysts that are put under extreme conditions are required to produce this hydrogen. In conjunction with three other researchers, Karl Mayrhofer is therefore searching for robust and cost-effective accelerators for such reactions.

Electricity from wind power, solar cells, and other sustainable sources either has to be used immediately or stored. Effective batteries are available for smaller applications, electric vehicles or for the home. Hydrogen produced from water using electricity will become increasingly important for larger applications such as in the steel industry or for railways on tracks that are not electrified. Karl Mayrhofer, Chair of Electrocatalysis at FAU and director of both the Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN) and the Institute of Energy Technologies (IET) at Forschungszentrum Jülich, carries out research on catalysts for this reaction.

Mayrhofer had already focused on climate change, a process that is being accelerated by modern civilization, and potential countermeasures as early as 1996 when he started his degree: “As a chemist, I can hopefully contribute to solving these problems and look for technical solutions,” he thought at the time. After completing his studies in his native Austria at TU Wien (Vienna), he decided to complete his Master’s thesis in industry. “This is where I conducted research on fuel cells that were powered by hydrogen.”
This was followed by a doctoral thesis completed at TU Wien and during a stay at the Lawrence Berkeley National Laboratory in California, USA, which involved more research into the chemical reactions required for producing hydrogen. This is where he met Matthias Arenz, whom he later joined at TU München, in order to continue research into catalysts for water electrolysis and extracting hydrogen from water. Arenz is now head of the Department of Chemistry at the University of Bern, while Karl Mayrhofer came to FAU via the Max-Planck-Institut für Eisenforschung in Düsseldorf, and the close collaboration between these two researchers continues to be very important for the success of both groups.

Electrolysis even makes platinum age

The reason for this research is obvious: “Sustainably-produced hydrogen not only stores energy, but can also be produced in regions with large amounts of solar power such as Australia, the Middle East or North Africa,” explains Karl Mayrhofer. “For example, if it is stored in liquid organic hydrogen carriers, which are also being researched at FAU and HI ERN, it can be transported relatively easily to central Europe in tankers.” In addition to solar power, of which there is a plentiful supply, the production of cost-effective hydrogen also needs another ingredient: A good catalyst.

It has been available in the lab for a long time, where the costly precious metal platinum is often used. This has been working extremely well for several decades, but it has one major drawback for the large-scale production required for the energy transition: “The reaction operates at high voltages and in extremely acidic or extremely alkaline solutions that place huge strain even on catalysts made of precious metals and therefore make them age very quickly,” explains Karl Mayrhofer. In business terms, this means the life of such electrolysis plants is limited, which makes hydrogen production quite expensive. “This would be very bad news for the energy transition,” says Mayrhofer.

Finding the perfect material

To solve this problem, he has been examining the aging process of fuel cells and catalysts for water electrolysis since his doctoral thesis. He is attempting to understand the processes that make important components more durable and thus make hydrogen production more cost-effective. The aim is to produce catalysts with an operating life of more than ten years. Due to the fact that it’s impossible to test suitable materials for such a long period of time, FAU researcher Mayrhofer is developing high-throughput processes that put the materials under extreme strain, thus recreating years of wear in a much shorter time in the lab. “These methods enable us to examine the aging process more quickly and more precisely in order to develop processes that at least slow down the deterioration,” explains Karl Mayrhofer.

“Our processes enable us to investigate in a short time what such catalysts will look like after ten or more years of operation.”

Prof. Dr. Karl Mayrhofer

These high-throughput processes at FAU form one of four pillars on which the Synergy Grant called “Directed Evolution of Metastable Electrocatalyst Interfaces for Energy Conversion” (“DEMI” for short) from the European Research Council (ERC) is based. The groundwork is supplied by a team from the University of Copenhagen, which is calculating how four or five components must be combined and what the surface structure should look like to enable the reaction to take place as efficiently as possible. A group from Ruhr-Universität Bochum uses these components to create model material libraries with varying concentrations, which Matthias Arenz and his team subsequently use to synthesize the combinations analyzed theoretically and in models in their labs as nanoparticles with highly active surfaces. “Our high-throughput process enables us to investigate in a short time what such catalysts will look like after ten or more years of operation,” says Mayrhofer about the fourth stage of the process towards producing a cost-effective and powerful catalyst for the high hopes being placed on hydrogen as a driver of the energy transition.

Author: Roland Knauer

This article is part of the FAU magazine

Innovation, diversity and passion: Those are the three guiding principles of our FAU, as stated in our mission statement. At FAU, we live these guiding principles every day in all that we do – in research, in teaching and when it comes to sharing the knowledge created at our university with society.

This, the second issue of our FAU magazine, underlines all of the above: It shows researchers who tirelessly keep pushing the boundaries of what has been believed to be possible. It introduces students who work together to achieve outstanding results for their FAU, talks about teaching staff who pass on their knowledge with infectious enthusiasm and creativity. And it reports back on members of staff with foresight and a talent for getting to the crux of the matter who are dedicated to improving the (research) infrastructure at FAU as well as people in key positions who are there for their university and are committed to its research location.