Many research groups are working on the development of new catalysts with which the greenhouse gas CO2 can be converted into valuable resources such as carbon monoxide (CO), that can be used in various industrial processes. In a recent study, a team around UniSysCat group leader Beatriz Roldán Cuenya from the FHI Berlin sheds light on the function of a nickel-based catalyst of great potential for the electrocatalytic reduction of CO2.
Nickel and nitrogen co-doped carbon (Ni-N-C) catalysts have shown exceptional performance in converting CO2 into CO, a valuable chemical feedstock. Still, their exact working mechanism remains unclear, hindering a fundamental understanding and a further improvement of such catalysts. The study presented here provides direct experimental insights into the structures formed on the surface of the catalyst and their evolution during the catalytic reaction. These insights help to understand the catalytic reaction very detailed and can be used to improve the design of nickel-based catalysts: Scientists are trying to intervene in the surface reaction in order to fine-tune the process and thus produce the desired products more efficiently.
To watch the Ni-N-C catalyst at work, the research team employed advanced in situ spectroscopy techniques like operando X-ray absorption spectroscopy (XAS) and valence-to-core X-ray emission spectroscopy (vtc-XES). In combination with machine learning and density functional theory, the experimental data could be used to show the local atomic and electronic structure of the catalyst in great detail.
Overall, this work demonstrates the power of a synergetic combination of advanced operando spectroscopies for understanding the catalytic mechanisms on single metal sites during electrocatalytic reactions. In particular, the study improves our understanding of nickel-based catalysts and paves the way for future advances in CO2 reduction technologies. Understanding how these catalysts work will facilitate the development of even more efficient systems for converting CO2 into valuable products.
This study has been published in Physical Review Letters: Adsorbate Configurations in Ni Single-Atom Catalysts during CO2 Electrocatalytic Reduction Unveiled by Operando XAS, XES, and Machine Learning, A. Martini, J. Timoshenko, P. Grosse, C. Rettenmaier, D. Hursán, G. Deplano, H. Sang Jeon, A. Bergmann, B. Roldan Cuenya, Phys. Rev. Lett. 133, 228001, https://doi.org/10.1103/PhysRevLett.133.228001