Pattern Formation in Catalytic H₂ Oxidation on Rh: Zooming in by Correlative Microscopy

Abstract

Spatio-temporal nonuniformities in H₂ oxidation on individual Rh(<i>h</i> <i>k</i> <i>l</i>) domains of a polycrystalline Rh foil were studied in the 10^-6 mbar pressure range by photoemission electron microscopy (PEEM), X-ray photoemission electron microscopy (XPEEM), and low-energy electron microscopy (LEEM). The latter two were used for in situ correlative microscopy to zoom in with significantly higher lateral resolution, allowing detection of an unusual island-mediated oxygen front propagation during kinetic transitions. The origin of the island-mediated front propagation was rationalized by model calculations based on a hybrid approach of microkinetic modeling and Monte Carlo simulations.