Site-selective surface reactions: nitric oxide reduction on Mo(110)

The catalytic reduction of NO(x) compounds formed in combustion processes is a critical factor in maintaining a clean environment. The introduction of the "catalytic converter" has been extremely effective in reducing these pollutants in automobile exhaust over the last two decades. Nevertheless, new environmental regulations have necessitated the development of processes that operate over a wider range of conditions and that are more efficient, so that NOx emissions can be reduced further. The need for new catalysts and processes has motivated a considerable number of studies of NO reduction using metal oxides as catalysts. In order to better understand the mechanisms for NO reduction on oxides, we have systematically studied the reactions of NO on thin-film oxides grown on Mo(110). By using a thin-film oxide, we are able to change the type of coordination sites that are available for NO binding and to use surface-sensitive spectroscopies to identify intermediates on the surface. We specifically explore the role of low-temperature NO coupling to a dinitrosyl species in our work and contrast this reaction to the higher temperature process, NO dissociation followed by nitrogen atom coupling.