Max Planck Research Group - Electrochemistry for Energy Conversion

The Electrochemistry for Energy Conversion group primarily aims to utilize electrochemical methods coupled with surface science and other instrumental analysis techniques to investigate the links between surface and electrolyte properties and electrocatalytic activity. The focus is on reactions that are of interest for energy conversion, storage and utilization. Applications and inquiries from highly motivated master students are welcome. Generation of fuels from electricity One of the proposed ways of addressing the challenges of the intermittency of renewable energy sources is the development of the so-called “Hydrogen Economy”. In this concept electricity from renewables at peak production would be used to produce hydrogen by water electrolysis. Such hydrogen could later be used in fuel cells to generate electrical energy, thus allowing energy storage from renewable energy sources.

The reactions taking place in an electrolyzer are the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), while in a fuel cell they are the oxygen reduction reaction (ORR) and the hydrogen oxidation reaction (HOR). In both cases the oxygen-reactions (OER and ORR) have slower kinetics and are the bottleneck to making these devices more efficient. Additionally, the catalysis of these reactions often requires costly noble metal catalysts (such as Pt), so there is considerable interest in finding more economical alternatives.

The Electrochemistry for Energy Conversion group investigates the influence of bi-, tri- and multicomponent alloys, surface and near-surface alloys, as well as surface structure and electrolyte composition on the electrocatalytic properties towards these key reactions. The group seeks to further the prospects of rational catalyst design by linking the activity, selectivity and stability of these catalysts to assessable physical properties.

Using electricity to produce wide-use chemical products

Another route for the utilization of electric power is the direct synthesis of wide-use chemicals. For instance, ORR can go through two different pathways, the so-called 4-electron one, which is desirable in fuel cells, and the 2-electron one which is not desirable in that case, but results in the generation of hydrogen peroxide, which is a widely used chemical an oxidant and a disinfectant. Therefore, a good control of the selectivity of ORR is of high interest for different applications.

Ammonia is the second most produced chemical in the world, and it is produced in the well-known and highly optimized Haber-Bosch process. Nonetheless, since the Haber-Bosch process requires high temperatures and pressures, it requires large centralized facilities. Therefore, there is certain interest in developing processes that could use renewable electricity and function in a more decentralized manner. Electrochemical ammonia synthesis in that sense would be an interesting option. While electrochemical ammonia synthesis has been investigated for decades, it suffers from very different challenges compared to, e.g., hydrogen peroxide production, which is already commercially applied to some extent. The lack of standards, protocols and general understanding of the challenges of the reaction have led to a general state of confusion regarding the viability of the process. Only recently have these issues been seriously addressed (see e.g. [2]) and the main challenge in this field is the proper, standardized, and reliable testing of catalytic systems. This should enable the creation of a much clearer picture about the potential, or lack thereof, of such systems.