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How the facets of a platinum nanoparticle control catalytic properties

​​​​​​​​​​​​​​For the first time, researchers at IRIG and CNRS have used the ESRF synchrotron in Grenoble to measure the deformation of a single platinum nanoparticle in an electrochemical solution. This provides an in-sight into the properties of this material, which is used in particular as a catalyst in fuel cells and water electrolyzers.​

Published on 23 June 2023

​Nanoparticles offer a significant advantage over solid materials: their nanometric di-mension consid-erably increases contact surfaces, thus enhancing their catalytic activity and selectivity. This ena-bles chemical processes to be carried out using fewer reagents, reducing energy consumption and therefore costs. However, as these particles are highly complex, it has not been possible to charac-terize them individually until now. Average measurements were carried out on at least a hundred nanoparticles. Information on their structural properties and the respective contributions of their vari-ous catalytic sites was therefore only known on average.

Thanks to the extremely high resolution and brilliance of the ESRF synchrotron's X-rays, it has become possible to characterize a single platinum nanoparticle with a resolution of just a few nanometers. Researchers at IRIG, in collaboration with CNRS-LEPMI and ESRF, were able to determine the precise structure, shape and nature of the facets, as well as the distribution of deformations, via the displacement of atoms. What's more, the use of a brillant beam at ESRF enabled these measurements to be carried out during the catalytic activity of the nanoparticle, under electrochemical conditions, which had never been done before in a liquid medium. These studies revealed that, contrary to what was previously thought, the deformation induced by catalytic reactions propagates very heterogeneously throughout the volume of the platinum nanoparticle and not just on its surface, particularly at the edges, corners and facets. In fact, the deformation of a particle is closely linked to catalytic activity and has a positive influence on the reaction.

More generally, the feat of carrying out these operando measurements will enable us to understand how to improve the efficiency of nanocatalysts, particularly in fuel cells and water electrolyzers. 
The researchers will complement their work with theoretical studies. The results could be applied to synthesize catalysts with optimized activity, selectivity and lifetime.

Artist view of the facets of a platinum nanopartcle
(credit: C.Atlan & C.Chatelier / CEA)

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