Abstract

Recent progress in instrumentation has provided the basis for characterizing the surfaces of catalytically active oxide materials by using surface-ligand IR (SLIR) spectroscopy. Reference data have been obtained for molecular ligands, in particular for CO bound to macroscopic, well-defined oxide single-crystal surfaces, and now allow identifying the facets exposed by nanoparticles. These advances are highly beneficial in the context of in situ and operando studies on catalytically active powder materials, thus allowing the observation of dynamic changes of the shapes of oxide nanoparticles as well as the number, size, type, and charge state of exposed metal particles/clusters. In particular, the SLIR method can also be used to identify single-atom active sites in heterogeneous catalysis. Finally, such accurate reference data acquired for well-characterized monocrystalline surfaces are required to validate theoretical approaches.

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