Decomposition of ammonia on O- and S-covered Ru(001) surfaces

Abstract

The decomposition of ammonia on oxygen- and sulfur-modified Ru(001) surfaces was investigated at a surface temperature of 480 K using the thermal desorption technique. On an O-covered Ru(001) surface, two thermal desorption peaks of nitrogen were observed. In addition to the broad feature centered around 750 K, a sharp peak was observed at 640 K, growing in intensity with oxygen coverage. These results can be qualitatively explained by the repulsive interactions between the adsorbed nitrogen and oxygen atoms. Our work further revealed that sulfur adatoms significantly inhibit the decomposition of ammonia. At a sulfur coverage of 0.6, no nitrogen desorption could be detected. In contrast, the presence of oxygen adatoms on Ru(001) only slightly affected the amount of ammonia decomposed. The coverage of N(ads) from ammonia decomposition on an O-saturated surface was similar to that on clean Ru(001). © 1994.