Using intense X-ray light, a DESY-led research team has observed a single catalyst nanoparticle at work. The study shows for the first time how an individual nanoparticle changes the chemical composition of its surface under reaction conditions, making it more active. The study is an important step towards a better understanding of real catalyst materials.
However, despite their widespread use, we still do not know many important details of how different catalysts work. A technique has now been developed with which individual nanoparticles can be labeled and thus identified in the sample. For the study, nanoparticles of a platinum-rhodium alloy were grown on a carrier material in the laboratory and a special particle was marked. This has a diameter of around 100 nanometers and is similar to particles used in car catalytic converters.
Using X-ray light from the European Synchrotron Radiation Facility ESRF in Grenoble (France), the team was not only able to create a detailed image of the nanoparticle, but also measure its surface tension. Under operating conditions, such as in an autocatalyst, rhodium atoms migrate from the inside of the particle to the surface because rhodium interacts more strongly with oxygen than platinum. As a result, the surface tension and shape of the particle change. However, the chemical composition of the surface, shape and size of the particles have a considerable influence on their function and efficiency.
