Catalysts are often made of expensive precious metals, which work most efficiently when very small particles of the metal are fixed to a less expensive carrier, such as magnetite (iron oxide). But the smaller the particles are, the more they have a tendency to move and join to form larger particles. Scientists at TU Wien (Vienna, Austria) and Utrecht University have identified how carbon monoxide plays a role in the mobility of these particles, but also the stability of clusters of several platinum atoms on a magnetite surface. The researchers announced their findings in a publication in Proceedings of the National Academy of Sciences on 25 July.
Influence of carbon monoxide
The platinum atoms are held in place by oxygen atoms in the magnetite, but on some other surfaces they tend to form larger particles of the metal. However, binding to a molecule of carbon monoxide can cause the platinum atoms to separate from the surface, an effect known as the ‘skyhook effect’. Together with the carbon monoxide molecule, the platinum atom can then move over the surface of the magnetite. This causes platinum atoms to come together to form clusters that are so stable in the presence of carbon monoxide that they cannot grow into larger units. The study showed how the behaviour of individual metal atoms and clusters of atoms can be influenced by the molecules present, which is essential in order to understand the stability and life cycle of catalysts.
The publication is based on data collected by Jessi van der Hoeven (Utrecht University) during her Master’s internship at TU Wien. During her Master’s in Nanomaterials Science, she worked there for six months as a chemist in a physics research group. It was an intriguing partnership, because both fields studied the same processes, but at a different level. In Vienna, Van der Hoeven worked with unique equipment that enabled her to study catalytic processes at an atomic resolution.
Not the first publication
According to the co-author of the publication, Prof. Petra de Jongh, Van der Hoeven worked unbelievably hard during her internship. Another high-impact publication based on her measurements appeared in Angewandte Chemie last year, followed by the recent publication in PNAS. And preparations are currently underway for a third publication about her data.
Towards her PhD.
Upon completion of her Master’s in 2014, Van der Hoeven began her PhD. research under the supervision of Prof. Petra de Jongh (Inorganic Nanomaterials) and Prof. Alfons van Blaaderen (Soft Condensed Matter). Van der Hoeven is currently focusing on the stability and self-organising characteristics of gold catalysts at a much larger scale, in which she is also studying the influence of light on catalytic processes.
Publication: Bliem et al., "Dual role of CO in the stability of subnano Pt clusters at the Fe3O4(001) surface", Proceedings of the National Academy of Sciences (2016); doi: 10.1073/pnas.1605649113