Prize-worthy research on efficient energy conversion

31 October 2013 by Beatrix Dumsky, posted in Electrochemistry

Prize winner Dr. Karl Mayrhofer, Max-Planck-Institut für Eisenforschung, Düsseldorf. Foto: BASF

The international Science Award Electrochemistry from BASF and Volkswagen goes in 2013 to Dr. Karl Mayrhofer, Max-Planck-Institut für Eisenforschung, Düsseldorf. Mayrhofer, born 1977 in Villach, Austria, received the prize connected with €50.000 for the outstanding results of his research on electrocatalysts, which are crucial for the life expectancy of fuel cells. Mayrhofer who also leads the Electrocatalysis Group at the MPI in Düsseldorf gave us insight into the world of electrocatalysis and what part it plays in energy conversion.

Dr. Mayrhofer congratulations to the Science Award Electrochemistry 2013. The jury selected you for your work on highly active and stabile electrocatalysts for efficient electrochemical energy converters. What are electrocatalysts and what exactly was your contribution?

Electrocatalysts increase the speed of electrochemical reactions and make a significant contribution to improving the energy balance in fuel cells, new promising battery systems or in water splitting. Electrocatalysis is part of the field heterogeneous catalysis.

We have a holoistic approach: By developing innovative methods, we have extended the fundamental understanding of electrocatalysis and based on that we worked on a higher catalytic activity, new more effective structural designs and material concepts. I deliberately say “we” because not I alone have received the prize, it is much more my whole team consisting of eight doctoral candidates, five postdocs and a technician, as such work can only be achieved together.

What role do electrocatalysts play in fuel cells?

The noble metal catalysts are responsible for the reduction of oxygen in fuel cells. Without a catalyst this chemical reaction is kinetically inhibited. That means the reaction doesn’t work well or not at all. Up to now we need a large amount of noble metals, which naturally increases the cost. The goal is to reduce the amount of necessary noble metals and ideally, cope entirely without.

Saving noble metals and still ensuring high activity – how is that supposed to work?

A multitude of phenomena in the cell restrains the activity and reduces the stability. We need to understand the processes before we can develop solutions.

And you now know what happens in the cell?

Our new experimental and analytical methods enabled the direct visual investigation of the electrochemical degradation of different catalysts. Using electron microscopy, we succeeded for the first time in investigating the identical nanometer-size catalyst particle before and after the electrochemical cell had been in operation. With this method we could virtually see the structural transformations such as particle dissolving or melting together and corrosion of carrier material and dissolution from the carrier material.

You conduct true basic research. What practical use does your research already yield today?

With our unique method of coupling a high resolution element analysis to a high throughput electrochemical flow cell, we are able to investigate model catalysts and determine their activity, stability and selectivity simultaneously. And with this comprehensive information we can identify the optimum composition.

Hollow graphitic spheres (HGS) mit platinum nanoparticles

The newly developed very stable Pt@HGS fuel cell catalyst: green porous hollow graphitic spheres (HGS) with red platinum nanoparticles inside. (Source: MPIE & MPI-KOFO)

This method is universal and not only interesting for current topics around alternative energy conversion such as electrolytic water splitting, CO2-reduction and fuel cells, but also for corrosion protection.

The understanding and knowledge we have achieved with our new methods, has already lead to the design of new, more stable electrocatalysts. When the materials used are more stable, less material is needed which again leads to a reduction in cost. Together with Ferdi Schüth and Carolina Galeano, Max-Planck-Institut für Kohlenforschung in Mülheim, we developed mesoporous cage-like graphitic spheres (hollow graphitic spheres) with a very high specific surface in which the platin alloy catalysator is trapped in. So the catalysator can not undergo dissolution so easily and the high surface area of the porous material enables a large amount of operating catalysator in a very limited area. (Link to publication: Toward Highly Stable Electrocatalysts via Nanoparticle Pore Confinement).

Are you already also working together with companies?

Yes, precisely on the field anti-corrosion coatings we are collaborating with Arcelor Mittal and Thyssen Krupp Steel. For them our knowledge about dissolution processes is especially valuable. And for Umicore we are optimizing catalysts.

Where does the track lead to? What are the greatest challenges in the near future?

To further develop the in-situ diagnostics. The present method is very elaborate and takes two days to complete: First we have to locate the particle on the nanometer-scale, take a picture, then measure it and subsequently pinpoint the particle for measuring again. Electronic microscopy generally operates using vacuum. But researchers have recently shown that it’s possible to generate microscopic images through thin liquid layers. With such an in-situ electron microscopy we could directly watch the processes as they are happening. That would be exciting and would spare us a huge amount of time.

What would you be, if you weren’t an electrochemicist?

I’ld most probably be an atmospheric researcher. During my studies I had thought about going in that direction. The whole complex of energy and environmental issues is definitely the driving force behind my research.

Interview conducted by Beatrix Dumsky

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