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Determining the Activity of Catalyst Particles Free of Precious Metals

Chemistry

Determining the Activity of Catalyst Particles Free of Precious Metals

[04.10.2019]

Precious metal-free nanoparticles could serve as catalysts for the production of hydrogen from water. Because they are so small, their properties are difficult to determine. Materials Chain chemists have now developed a new process with which they can characterize individual precious metal-free nanoparticle catalysts.

The particles could be a cheap alternative to precious metal catalysts in order to obtain hydrogen from water by electrolysis. "In order to develop effective nanoparticles, we need to understand how the structure and activity of individual particles or small particle groups are related," says Prof. Dr. Wolfgang Schuhmann from the Center for Electrochemistry at Ruhr-University Bochum (RUB). He describes a new measurement method for this purpose with the Bochum researchers Tsvetan Tarnev and Dr. Harshitha Barike Ayappa as well as Prof. Dr. Corina Andronescu from the University of Duisburg-Essen (UDE) and other colleagues in the journal "Angewandte Chemie", published online on 26 July 2019.

So far, there are few techniques available to measure the catalytic activity of individual or fewer nanoparticles. "The currents that have to be measured are extremely small and it is necessary to find individual or a few nanoparticles and be able to measure them reproducibly," Schuhmann explains. The research team, which cooperates within the University Alliance Ruhr, showed that such analyses are also possible with high throughput - namely with electrochemical scanning cell microscopy.

New reference system developed

Until now, the method had not been used for this purpose because the nanoparticles had to be tested under demanding chemical conditions and thus large measurement inaccuracies occurred. This made a reliable interpretation of the results impossible. In their current work, the researchers developed a new reference system for electrochemical scanning cell microscopy. By cleverly using a stable internal standard, they eliminated the measurement inaccuracies and enabled long-lasting measurements under the given conditions with high throughput.

Self-made nanoparticles analyzed

The researchers produced carbon particles with nitrogen and cobalt inclusions on a plate of glassy carbon, the particles being present on the surface either individually or in groups of a few particles. In a single experiment, they were able to use scanning cell microscopy to determine the electrochemical activity of these particles or particle groups.

The particles catalyzed the so-called oxygen development reaction. The electrolysis of water produces hydrogen and oxygen - the limiting step in this process is currently the partial reaction in which the oxygen is produced; more efficient catalysts for this partial reaction would simplify the production of hydrogen.

 

Original publication:
Tsvetan Tarnev, Harshitha Barike Aiyappa, Alexander Botz, Thomas Erichsen, Andrzej Ernst, Corina Andronescu, Wolfgang Schuhmann: Electrochemical Scanning Cell Microscopy Investigation of Individual ZIF-Based Nanocomposite Particles as Electrocatalysts for Oxygen Development in Alkaline Media, in: Angewandte Chemie, 2019
DOI: 10.1002/ange.201908021

Tsvetan Tarnev, Harshitha Barike Aiyappa, Alexander Botz, Thomas Erichsen, Andrzej Ernst, Corina Andronescu, Wolfgang Schuhmann: Scanning electrochemical cell microscopy investigation of single ZIF-derived nanocomposite particles as electrocatalysts for oxygen evolution in alkaline media, in: Angewandte Chemie International Edition, 2019
DOI: 10.1002/anie.201908021

 

Further information:
Prof. Dr. Wolfgang Schuhmann, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Tel. 0234 32 26200, wolfgang.schuhmann@rub.de

Editor: Dr. Julia Weiler, RUB