ONE-DIMENSIONAL REACTIVITY IN CATALYSIS STUDIED WITH THE SCANNING TUNNELING MICROSCOPE

THE scanning tunnelling microscope (STM) has yielded great insight into the structure of surfaces and into the dynamics of surface reconstruction and adsorption1. We show here that it can also provide direct information about the microscopic mechanisms of catalytic reactions on surfaces. We have studied the oxidation of carbon monoxide on an oxygen-precovered rhodium (110) surface, a process related to the catalytic removal of CO in exhaust gases2,3. The STM images show that the reactivity is strongly influenced by the oxygen-induced reconstructions of the surface. The reaction is initiated at high-energy adsorption sites, mainly at steps and domain boundaries of the adsorbed oxygen layer. The CO strips away one-dimensional islands of oxygen atoms on the reconstructed surface, proceeding in the [011] direction. More generally, these results show how the STM can provide insights into the microkinetics of surface reactions.