New insights on catalytic nanoparticles synthesis

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Efficient catalysts are able to facilitate the chemical reactions that split water molecules into hydrogen and oxygen and vice versa, i.e. the conversion of hydrogen fuel into electric energy. Therefore, catalysts are essential for green hydrogen-based energy technologies using renewable power coming from solar or wind generators. Importantly, their performance is largely determined by their surface properties.

Controlled fabrication of nanoparticles through metal exsolution: the movement of metal oxide ions dispersed in a functional oxide is strongly influenced by an internal electric field (space charge region). The ions are chemically reduced at the surface and nucleate in the form of metallic nanoparticles. Copyright: Thomas Pössinger, RWTH Aachen / Moritz L. Weber, Forschungszentrum Jülich

Within this context Dr Moritz Weber, Dr Felix Gunkel, Dr Christian Lenser and colleagues from the Forschungszentrum Jülich (FZJ) described the complex reactions that take place during metal exsolution – a solid-state reaction where metallic nanoparticles segregate from a functional oxide, allowing to obtain a tailored design of catalyst particles – on an atomic level. They explain the fundamental processes that occur during the formation of the nanoparticles and demonstrate that the kinetics of such reactions depends on the electrostatic interaction between the exsolution-active species and the electric field at the surface of the underlying functional oxide. To do so, FZJ researchers – supported by Dr Smid Bretislav, Charles University of Prague – used near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) available at the Czech CERIC Partner Facility.

These findings represent a significant improvement in the understanding and degree of control of nanoparticles in metal exsolution catalysts, particularly relevant for high-temperature fuel and electrolysis cells, and pave the way for the development of catalysts based on abundant metals, eliminating the need for expensive and hard to come by noble metals.

ORIGINAL ARTICLE:

Space charge governs the kinetics of metal exsolution
Weber M.L., Šmíd B., Breuer U., Rose M.-A., Menzler N.H., Dittmann R., Waser R., Guillon O., Gunkel F., Lenser C., Nature Materials2024