Distinct reaction mechanisms in the catalytic oxidation of carbon monoxide on Rh(110): scanning tunneling microscopy and density functional theory studies.

By means of scanning tunneling microscopy measurements and density functional theory calculations, we identify the reaction mechanism for the oxidation of carbon monoxide to carbon dioxide on the Rh(110) surface at 160 K, which appears to be completely different than the one active at room temperature. The reasons for these different behaviors are determined. Our results demonstrate that even for a very simple catalytic reaction, the microscopic mechanism can dramatically change with temperature, following pathways that differ for nucleation sites and surface propagation and involve different surface moieties.