Reply to comment on "CO oxidation on ruthenium: the nature of the active catalytic surface" by H. Over, M. Muhler, and A.P. Seitsone

• Published in: Surface science 2007-12, Vol.601 (23)
• Main Authors: Goodman, David W., Peden, Charles HF, Chen, Mingshu
• Format: Article
• Language: English
• Subjects: CARBON MONOXIDE; CATALYSTS; CATALYTIC EFFECTS; Environmental Molecular Sciences Laboratory; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; OXIDATION; RUTHENIUM; RUTHENIUM OXIDES
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2007.09.042

We first state that the premise of our Letter [1] was to state emphatically that the early studies of Peden and Goodman (PG) [2] can be entirely explained by and are only consistent with the active surface being a monolayer oxygen-covered Ru(0001) surface. Contrary to the authors’ contention in their Comment, the reaction conditions addressed in the experiments of PG [2] spanned the temperature range 375 to 600 K, a pressure range of O2 and CO pressures from 0.5 to 500 Torr, and CO/O2 ratios from 60 to .03. The authors state in their introduction that “the oxidation of Ru metal takes place to RuO2 only for temperatures higher than 500 K. Here we do not wish to address the oxidation of Ru in all morphologies, but rather the specific reaction conditions required for RuO2 to form on Ru(0001), the catalyst used in the experiments of PG and the subject of our previous Letter [1]. Indeed, as pointed out in our Letter [1], Over and coworkers in a very definitive piece of work [3] showed that the critical conditions required for the formation of RuO2 on Ru(0001) were far outside those used in the experiments of PG with respect to temperature and oxygen chemical potential. Based on our earlier studies [2] and the work of Over and coworkers [3] we concluded in our Letter that RuO2 could not have formed to any appreciable extent in the PG experiments.