For the first time, researchers have investigated how much electrical charge nanoparticles transfer to their support. Image: Sergey Kozlov and Oriol Lamiel.
For the first time, researchers have investigated how much electrical charge nanoparticles transfer to their support. Image: Sergey Kozlov and Oriol Lamiel.

The unique properties of nanoparticles have led to their widespread use in modern production and environmental technologies, from catalytic processes in the chemical industry to environmental catalysis to new types of solar cells or new electronic components. These unique properties often arise from chemical interactions between the nanoparticles and the support material they are placed on. Such interactions can alter the electronic structure of the nanoparticle, through the exchange of electrical charge.

Researchers from Germany, Spain, Italy and the Czech Republic, led by Jörg Libuda at the University of Erlangen-Nuremberg, have now succeeded in counting the number of elementary charges lost by a platinum nanoparticle when it is placed on a typical oxide support. As the researchers report in Nature Materials, this work brings the possibility of developing tailor-made nanoparticles a step closer.

One of the main questions that nanoscience researchers have been discussing for some time now is how nanoparticles interact with the support they are placed on. It is now clear that various physical and chemical factors, such as a nanoparticle’s electronic structure, nanostructure and – crucially – interaction with the support, determine its properties. Although this interaction – specifically the transfer of electrical charge – has already been observed to a great extent, previous studies have not investigated how much charge is transferred and whether there is a relationship between the transfer and the size of the nanoparticle.

In order to measure the electrical charge exchanged between a nanoparticle and its support, the researchers prepared an extremely clean and atomically well-defined oxide surface, onto which they placed platinum nanoparticles. Using synchrotron-radiation photoelectron spectroscopy and scanning tunneling microscopy, they were then able to quantify the interaction between the nanoparticles and the support for the first time.

Looking at particles with various numbers of atoms, from several to many hundred, they counted the number of electrons transferred and showed that the effect is most pronounced for small nanoparticles with around 50 atoms. The magnitude of the effect is surprisingly large: approximately every tenth metal atom loses an electron when the particle is in contact with the oxide.

The researchers were also able to use theoretical methods to show how the effect can be controlled, allowing the chemical properties to be modified to better suit their intended application. This would allow raw materials and energy to be used more efficiently in catalytic processes in the chemical industry, for example.

This story is adapted from material from the University of Erlangen-Nuremberg, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.