FOCUS TOPIC: From MIT to Wannsee

The aim of Marcel Risch’s current project at HZB is to investigate the mechanism by which oxygen forms when water is split catalytically. © HZB/M. Setzpfandt

Newly set up: In the laboratory in BWannsee, Marcel Risch (r.) and his doctoral student carry out measurements of electrocatalysts.

For Marcel Risch, it feels like a homecoming: as a student, he had previously run experiments at the Berlin particle accelerator BESSY II. After working for several years at Massachusetts Institute of Technology (MIT) and then in Göttingen, he is now establishing his own group at HZB – supported by funding from the European Research Council.

Marcel Risch remembers his first visit to the Berlin particle accelerator vividly: “We had to drive a whole truckload of material through Berlin for it,” he says with a chuckle. That was in 2008. He was just finishing his doctorate at Freie Universität Berlin, and the first sample he studied at BESSY II was cobalt oxide. “We prepared the experiment painstakingly and of course, even as a newbie, I spent days helping to set it up before we could start with the measurements.” More than a decade since these laborious beginnings, the experiment has now grown into a highly regarded research project: Risch has received one of the prestigious Starting Grants from the European Research Council (ERC) – and is now using the approximately 1.5 million euros in funding to establish his own group at HZB.

Marcel Risch’s research project falls into the field of renewable energies, a matter that is dear to his heart. “I find the topic doubly interesting: for society and, of course, from a scientific perspective,” he says. He currently commutes between the two HZB locations. In Adlershof, he uses the synchrotron source BESSY II, and in Wannsee, he is currently setting up a laboratory for experiments in electrocatalysis. “Of my two desks, however, this is the one I sit at the most,” Risch says, showing us around his office in Wannsee. It is full of books and a few pot plants (“I’m away so often, I have artificial ones that don’t need watering”), and by the time he gets here each morning, he has already completed the first part of his exercise regime: every day, he rides his bike from Potsdam, where he has settled with his partner and newly born son. “I take the nicest route, not the fastest,” he says cheerfully. “It might take half an hour, but it takes me past Cecilienhof Palace and over the Glienicke Bridge.”

It didn’t take long for Marcel Risch to feel at home in Berlin – indeed partly because he had already worked here for some years during his doctorate. Back then, Berlin was a stopover on his way to the most prestigious research institutes and universities, one of these being the Massachusetts Institute of Technology (MIT). “I had already decided at school that I wanted to study physics,” recalls Risch, who grew up in Darmstadt. Physics and chemistry were his favourite subjects, and he was lucky with his teachers. They inspired his curiosity, by using a CD to split light into all its spectral colours, for example, or – when the students were older – by precisely measuring the decay curve for the foam on various brands of beer. As an exchange student, he attended Darmstadt’s partner university in Saskatchewan, Canada, to brush up on his English. He was also fortunate enough to meet the right people during his later studies: in answering a call for applications on “natural photosynthesis”, he encountered his future doctoral supervisor. Then, a few years later, he saw an announcement for a conference on solar fuels to be held at MIT, and attended the conference with a DAAD scholarship. He made full use of that opportunity: “I went straight to the offices of the professors who were working on my topic, just to make contact,” he says. His door-to-door knocking paid off. From 2012 to 2015, he worked as a postdoc at MIT with varying duties. After that, back in Germany, he established a workgroup at Georg-August-Universität Göttingen, where he still works concurrently to his activities at HZB.

The aim of Marcel Risch’s current project at HZB is to investigate the mechanism by which oxygen forms when water is split catalytically. The project is called “ME4OER – Mechanism Engineering of the Oxygen Evolution Reaction” and it addresses an issue that could be pivotal in the energy transition: rather than convert solar energy directly into electricity and feed it into the grid, many researchers place their hopes in producing hydrogen from solar power instead. Hydrogen can be kept locally where it is needed, making it an especially efficient energy store. Whether converting to electricity or not, the bottleneck is the electrocatalysts that are used to split water into hydrogen and oxygen. So far, they are typically made from materials such as ruthenium or iridium, which are very expensive. Can they be replaced by cheaper alternatives? In his search, Risch is concentrating on oxides of relatively common transition metals such as manganese. These are inexpensive, but not very efficient in the oxygen evolution reaction. “The oxygen just kind of refuses to be produced,” Risch adds – and he is trying to change that: by analysing the reaction processes taking place on the material surfaces at the molecular level, he hopes to find a way to improve their properties. “I like to compare it with a map of a hiking trail: imagine you want to hike from point A to point B and want to minimize how much you have to travel up and down hill. So, you study the contour lines to find the flattest path,” Risch explains. This is, in essence, the same question he poses now: how can a reaction be influenced so that it avoids all obstacles and takes the most efficient pathway possible?

For this work, Marcel Risch wants to concentrate on only a few materials – specifically cobalt and manganese oxides – in order to elucidate their differences as thoroughly as possible. His first step will be to systematically investigate how chemical composition and major structural changes affect the reaction so that, in the next step, he can use this knowledge to make targeted improvements to the reaction.

Over the course of time, Marcel Risch has continually honed and refined his research question. In fact, he started doing so long before he successfully applied for the ERC Starting Grant: while at MIT, he applied for an Emmy-Noether scholarship, after which he applied to participate in the Young Investigator Programme of the Helmholtz Association. Nothing came of either application – but the discussions with the jury and feedback from the experienced researchers, Risch says, were so fruitful that he continued to develop his idea to increasing depth. The ERC finally awarded the grant for his project, which he can now tackle under optimum conditions thanks to this funding. Once the current start-up phase is completed, Marcel Risch’s team will consist of three doctoral students, who are currently being supported by two postdocs at HZB.

(Kilian Kirchgessner)