Nanoparticles can be used in many ways as catalysts. To be able to tailor them in such a way that they can catalyse certain reactions selectively and efficiently, researchers need to determine the properties of single particles as precisely as possible. So far, an ensemble of many nanoparticles is analysed. However, the problem of these investigations is that the contributions of different particles interfere, so that the properties of individual particles remain concealed. Researchers at Ruhr-Universiät Bochum in cooperation with colleagues from University of Duisburg-Essen and Technical University of Munich have developed a novel method in order to observe single nanoparticles before, during and after an electrochemical reaction. They depict the process in the journal Angewandte Chemie, published on 16 April 2019.

Observing the complete lifecycle

“To comprehensively understand the catalytic activity of a nanoparticle, we have to observe how its structure and composition change – from the pre-catalyst to the active catalyst and eventually all the way to the condition after the reaction,” explains Professor Wolfgang Schuhmann, head of the Center for Electrochemical Sciences. “This is why we have developed the particle at the stick.”
The researchers grew a catalyst nanoparticle at the tip of a carbon nanoelectrode, subsequently activated it and used it to catalyse an electrochemical reaction. Unlike previous approaches, the novel method made it possible for the team to observe the complete lifecycle of the particle.

Fabricating the particle at the stick

In the first step, the chemists modified the carbon nanoelectrode such that the particle preferably attaches to the tip of the electrode. Subsequently, they dipped the electrode’s tip into a solution, which contained the precursor materials for the catalyst. After that, these components assembled automatically, ultimately producing a symmetric particle, in which the constituting elements – the metal cobalt as well as the organic carbonaceous components – were evenly distributed.