Imaging Interface and Particle Size Effects by In Situ Correlative Microscopy of a Catalytic Reaction

The catalytic behavior of Rh particles supported by threedifferentmaterials (Rh, Au, and ZrO2) in H-2 oxidationhas been studied in situ by correlative photoemission electron microscopy(PEEM) and scanning photoemission electron microscopy (SPEM). Kinetictransitions between the inactive and active steady states were monitored,and self-sustaining oscillations on supported Rh particles were observed.Catalytic performance differed depending on the support and Rh particlesize. Oscillations varied from particle size-independent (Rh/Rh) viasize-dependent (Rh/ZrO2) to fully inhibited (Rh/Au). ForRh/Au, the formation of a surface alloy induced such effects, whereasfor Rh/ZrO2, the formation of substoichiometric Zr oxideson the Rh surface, enhanced oxygen bonding, Rh-oxidation, and hydrogenspillover onto the ZrO2 support were held responsible.The experimental observations were complemented by micro-kinetic simulations,based on variations of hydrogen adsorption and oxygen binding. Theresults demonstrate how correlative in situ surface microscopy enableslinking of the local structure, composition, and catalytic performance.

Automated summary

The catalytic behavior of Rh particles supported by different materials (Rh, Au, and ZrO2) in H-2 oxidation was investigated using photoemission electron microscopy (PEEM) and scanning photoemission electron microscopy (SPEM). Different catalytic performances were observed depending on the support and Rh particle size, with oscillations ranging from particle size-independent to fully inhibited. The experimental observations were supported by micro-kinetic simulations, which revealed the importance of hydrogen adsorption and oxygen binding in the catalytic process. This study highlights the significance of correlative in situ surface microscopy in understanding the relationship between local structure, composition, and catalytic performance.