Generating green hydrogen by mimicking nature
Transregional Collaborative Research Centre investigating solar energy conversion receives funding extension

Ulm University

Everyone knows the importance of solar radiation as a climate-friendly energy source. But long before major initiatives such as Europe’s Green Deal or Germany’s National Hydrogen Strategy, the Transregional Collaborative Research Centre (TRR) ‘CataLight’ had begun developing molecular systems that can function as solar radiation converters. For the researchers at the Universities of Ulm and Jena – the lead institutions in the CataLight consortium – the most important model for solar energy conversion is, of course, natural photosynthesis. Following four successful years working towards the decentralised generation of green hydrogen, funding has now been secured that will enable the CataLight research teams to continue with their important research. The German Research Foundation (DFG) has agreed to continue funding the Transregional Collaborative Research Centre (TRR 234) ‘Light-driven Molecular Catalysts in Hierarchically Structured Materials – Synthesis and Mechanistic Studies’ (or ‘CataLight’ for short). The CataLight TRR will receive a further €12 million in funds until 2026.

The Universities of Jena and Ulm are celebrating a major success. Over the next four years, an interdisciplinary team of researchers in the Transregional Collaborative Research Centre (TRR) ‘CataLight’ will be working to further optimise the process of photocatalytic water splitting in which carefully designed photocatalysts are able to use solar energy to split water into hydrogen and oxygen. A key component of this process is the optimisation of catalytic materials and methods involved. Earlier systems that were used to convert sunlight into chemical energy tended to be rather unstable. Progress towards solving the stability issue was made during the first funding phase of the CataLight TRR, when the chemists, physicists and materials scientists in the consortium were able to stabilise and control the process by embedding photoactive catalytic materials into soft matter matrices.
The main objective of the next phase of the Collaborative Research Centre is to establish a basis for the efficient decentralised production of carbon-neutral hydrogen. The number of potential applications is large, ranging from mobile solar-powered hydrogen fuelling stations to the climate friendly supply of electricity and heat to residential properties.

First funding period: solar fuel production in the dark and novel repair mechanisms

During the first funding phase of the CataLight TRR, the research teams made substantial progress towards the environmentally sustainable production of solar fuels. ‘The research groups at the Universities of Ulm and Jena complement each other perfectly. By working together we have been able to develop, test and link the molecular building blocks for solar energy conversion. Our work has yielded fundamental insights into the structure of light-driven catalysts, which has enabled us to improve the efficiency of the energy conversion process,’ explained Professor Sven Rau, Spokesperson of the CataLight TRR in the first funding period and Head of the Institute of Inorganic Chemistry I at Ulm University.
A number of key results from the first funding period include the development of a compact, single-molecule catalyst that, thanks to its ability to store light energy, is able to produce solar fuels in the dark, and the discovery of a novel molecular-level repair mechanism for photocatalysts. Inspired by the processes in natural photosynthesis, light-driven hydrogen formation can occur multiple times with the same molecule, which significantly extends the life of the system. One area of particular merit highlighted during the scientific evaluation of the CataLight TRR by the German Research Foundation (DFG) was the CataLight school project in which CataLight researchers developed and compiled teaching materials on the subject of artificial photosynthesis and made them available for use in chemistry lessons at the upper secondary level.

More sustainable photocatalysts

The focus in the second phase of funding, which begins in July 2022, will be on making photocatalysts that are more sustainable. At present, rare and expensive materials such as ruthenium, platinum or rhodium are still being used in the catalysts or in the reaction centres of the photo systems. The aim is to substitute these environmentally problematic components by more readily available alternatives. Organic dyes of the type studied in Jena may be able to provide a solution to this problem. While the instability of these organic molecules is a still an issue, it may be possible to solve it by using the repair mechanisms developed during the earlier phase of the CataLight TRR. ‘Another key objective in the second funding phase is to optimise the linkage of molecular light-driven catalytic units. The goal is to achieve a light-driven process with coupled oxidation and reduction. We will also be working on further improvements to the physicochemical analytical methods employed,’ explained Professor Benjamin Dietzek-Ivanšić from the University of Jena, who will be taking over as spokesperson during the second funding phase. The long-term goal of the Transregional Collaborative Research Centre (TRR) is to synthesise artificial chloroplasts that can mimic their natural counterparts, i.e. those plant cell components that are responsible for photosynthesis.

New partnerships strengthen the Transregional Collaborative Research Centre CataLight

In addition to the lead institutions, Ulm University and the University of Jena, the CataLight consortium also includes the University of Vienna, the University of Mainz, the Max Planck Institute for Polymer Research in Mainz and the Leibniz Institute for Photonic Technology in Jena. The consortium also plans to expand into a cooperative partnership with the Center for Solar Energy and Hydrogen Research (ZSW) in Ulm. TRR team member Professor Carsten Streb has taken up a professorship at the University of Mainz where he will continue to conduct research within CataLight. A number of researchers from the USA will also be joining the TRR as Mercator Fellows. CataLight is also a founding member of the CataLysis network of DFG-funded research initiatives in the field of catalysis.
The previous groundwork and the new partnerships are together paving the way for a successful second funding phase that will help facilitate the hugely important transition to zero-carbon energy sources.

Text and Press contact: Annika Bingmann
Translation: Dr. Andrew Symonds

Prof. Sven Rau
Prof. Sven Rau, Spokesperson of the CataLight TRR and Head of the Institute of Inorganic Chemistry I at Ulm University (photograph: Elvira Eberhardt/Uni Ulm)
Research work
Research work being carried out at Ulm University as part of the Transregional Collaborative Research Centre ‘CataLight’ (photograph: Elvira Eberhardt)
Catalyst solutions
Catalyst solutions containing luminescent ruthenium-based dyes under exposure to visible light radiation in the ‘Azula’ reactor (photograph: Elvira Eberhardt)