Hydrogen could play a central role in the energy transition. However, to produce it in an environmentally friendly way from water, catalysts are needed that are not only efficient but also long-lasting. Jasmin Finkelmeyer and Martin Presselt, along with a team from the University of Illinois Chicago, have investigated a new material combination that could make this possible.

Catalysts are crucial for the electrochemical splitting of water. They ensure that water molecules efficiently break down into their components, oxygen and hydrogen. Many of the catalysts used so far are based on rare metals like platinum and are prone to decomposition or clumping in solution. “Our goal is to find more sustainable alternatives,” says Dr. Martin Presselt. “To achieve this, we have contributed to better understanding the stability and electronic properties of the materials through our highly sensitive measurements, in collaboration with the team led by Ksenija Glusac from the University of Illinois Chicago.”

The researchers combined graphene nanoribbons, ultrathin carbon structures, with a rhodium-based catalyst. “The idea initiated by the Glusac group was to couple catalyst molecules to a conductive structure that enhances their stability and electronic properties. We helped by using exceptionally sensitive measurements to analyze the interactions more precisely,” explains Dr. Jasmin Finkelmeyer. “Graphene nanoribbons are particularly suited for this because they are electrically conductive and chemically robust.”

Indeed, it turned out that binding to graphene prevented the catalyst molecules from clumping together, which helps maintain their activity in the long term. Additionally, the nanoribbons allowed for controlled electron distribution, making the catalyst work more efficiently.

Finding the right balance

A key advantage: the new material remains stable across a wide pH range. While many catalysts are only effective in strongly acidic or alkaline solutions, the combination studied here remains active even under neutral conditions. “This makes the technology more versatile,” says Martin Presselt.

However, it’s important to tailor the design carefully. “If a material is poorly designed, the relaxation processes occur faster than the chemical reactions we want to drive,” explains Martin Presselt. “So, we must find the right balance between electronic coupling and reactivity.”

A step toward sustainable hydrogen

Hydrogen production faces the challenge of becoming more efficient and cost-effective. A stable, high-performance catalyst could help make electrolyzers more durable, and in the long run, make green hydrogen production more economical.

“The study shows that the choice of the support material has a significant impact on the performance of the catalyst,” says Jasmin Finkelmeyer. “The research team has found a promising approach that we now want to further develop.”

CataLight: Collaborative research for new catalysts

The study was conducted within the Collaborative Research Center CataLight, a partnership between the University of Jena and the University of Ulm, along with other partners. The research network explores how light-driven catalytic processes can be optimized – inspired by natural photosynthesis. “We aim not only to improve individual catalysts but also to better understand the fundamental principles of material development,” says Martin Presselt. “Our goal is to find sustainable alternatives to existing systems.”

Askins, E. J., Sarkar, A., Navabi, P., Kumar, K., Finkelmeyer, S. J., Presselt, M., Cabana, J., & Glusac, K. D. (2024). Interfacial electrochemistry of catalyst-coordinated graphene nanoribbons. Journal of the American Chemical Society, 146(32), 22360–22373. https://doi.org/10.1021/jacs.4c05250