Today, we have the pleasure of introducing Ariana Serban, a doctoral researcher at the École Polytechnique Fédérale de Lausanne (EPFL), in Switzerland. Serban works in the Laboratory of Inorganic Synthesis and Catalysis, led by Professor Xile Hu, where she develops non-PGM catalysts for our ANEMEL electrolysers.
Serban’s journey into electrochemistry, however, began in something unrelated to water splitting. She started her research in this field by developing 3D biocompatible platforms for electrochemical sensors, and then switched to electrochemical gas sensors. “In a hospital, it’s vital to measure the levels of oxygen and carbon dioxide in your blood. So, I was involved in Hoffmann-La Roche’s R&D project towards the launch of those sensors,” she explains.
For over a year now, she has immersed herself in the world of green hydrogen, aiming to develop solutions that will enable the transition from fossil fuels to renewable energy. ‘I thought it would be nice to make a difference here. I want my research to extend beyond the lab and have a real-world impact. I don’t know if I’m being naive,’ Serban reflects.
She isn’t. Serban is already making her contribution in this field. An electrolyser involves two chemical reactions: one produces oxygen, while the other produces hydrogen, each requiring a different catalyst. In her PhD at EPFL, she is primarily developing new electrocatalysts for the hydrogen evolution reaction, specifically with non-platinum group metals (PGMs). The current state-of-the-art catalysts are based on expensive materials, such as platinum or palladium.
She came up with an idea to tackle this issue. Serban had noticed that most research in this field tests catalysts at low current densities, around 100 milliamperes. This substantially increases the cost of hydrogen obtained through the process. ‘I thought that if we want to move towards the industrial sector and real-world applications, we should focus on higher current densities to pack more performance into a smaller size. By that, I mean something more significant, like one ampere or even higher,’ she says. However, those high currents lead to rapid catalyst degradation.
After thoroughly researching the topic, she decided to use self-supported catalysts to tackle the challenge ahead. This means growing the catalyst on a support, known as a gas diffusion layer (GDL), which allows gases to diffuse while providing a conductive pathway. The layer can be made of various materials such as nickel foam, nickel felt, or carbon paper. Serban employs a method called electrodeposition (or electroplating) to achieve this. It’s a widely used technique, for instance, in applications such as watches or boats, wherever a metal coating is needed.
It works through electrolysis – like our electrolysers –, a process that uses to drive a chemical reaction. This takes place in an electrodeposition cell, which consists of two electrodes: a working electrode, where the GDL is located, and a counter electrode. She typically uses a piece of carbon as the counter electrode. These electrodes are immersed in a solution that conducts electricity, known as the electrolyte. By applying a current between them two, the ions in the electrolyte migrate towards the working electrode. In her case, these species are reduced and combine to form an alloy on its surface. In summary, the current drives the reaction and deposits the desired material onto the working electrode, which is the GDL.
All of this may sound quite straightforward. However, our researcher has gone through a lot of trials and errors in the lab. Luckily, hard work paid off. Serban has developed some interesting catalysts, which she has been able to share with other ANEMEL partners for further tests and trials. In particular, she sent samples to our colleagues at Technische Universität Berlin, in Germany, and the University of Galway, in Ireland.
Serban has also started engineering her own electrolysers. She has optimised the materials used in the electrolysers, which allows her to better control parameters such as temperature, electrolyte feed, flow rates, and current distribution. Currently, she is using a concentrated potassium hydroxide solution with pH of 14, which is quite corrosive and significantly affects many of the materials. Therefore, it is crucial to choose appropriate materials to ensure a resilient and robust system. Serban is also concentrating on the interface between the catalyst and the GDL, as well as the electrodeposition protocols, to guarantee optimal performance.
Last year, Serban co-authored a paper in ACS Energy Letters, and this year, she was part of another publication in Angewandte Chemie, which demonstrated the durability of an AEM electrolyser for over 800 hours. There is also a third paper in preparation, in which Serban will be the first author, likely coming out later this year. Congratulations!
