Researchers have reconstructed and followed individual atoms inside platinum nanoparticles as the catalyst activated, deactivated and reactivated during carbon monoxide oxidation. Their operando electron-microscopy study links catalytic performance to changes in the number of exposed platinum atoms with few neighboring atoms.
The work tests two long-standing pictures of a catalytic active site. A Langmuir-like site sits on a relatively ordered crystal facet, while a Taylor-like site is an undercoordinated atom at an edge, corner or other irregular surface position. Real nanoparticles contain both structures, but measuring how they change during a reaction has been difficult.
The team combined atomic-resolution, three-dimensional transmission electron microscopy with quantitative image analysis while individual platinum particles passed through reaction cycles. Catalytic measurements and mass-spectrometry data were then compared with the reconstructed particle surfaces, allowing the researchers to follow structural changes under operating conditions instead of examining only the catalyst before and after use.
Both site types appeared within the same particle and could interchange as its surface reconstructed. The abundance of surface atoms with relatively few neighbors tracked catalytic performance across activation, deactivation and reactivation. That observation connects a particle's changing atomic geometry with its measured behavior rather than assigning activity to one fixed class of site.
The experiment covers carbon monoxide oxidation on individual platinum nanoparticles under an electron microscope. The imaging environment, electron dose and small particle sample do not reproduce every condition inside an industrial catalyst bed, and a correlation between undercoordinated atoms and activity does not by itself establish a universal design rule for other metals or reactions.
The immediate value is a way to compare the same nanoparticle across a complete reaction history and ask which surface atoms appear when activity rises or falls.