The adsorption and decomposition of NH3 and hydrogen on clean planar Ir(210) and on clean nanoscale-faceted Ir(210) were studied. Nanoscale facets developed on the initially planar Ir(210) surface when it was covered with oxygen and annealed at ≥ 600K. Ir(210) was very active for NH3 decomposition and the recombinative nitrogen desorption peak temperature was much lower compared to other transition metals. Striking differences were observed in recombination and desorption of molecular hydrogen, and in thermal decomposition of NH3 over clean faceted Ir(210) vs. clean planar Ir(210). NH3 decomposition on Ir(210) exhibited size effects on the nanometer scale. Ir might be a useful catalyst component for COx-free hydrogen production for potential fuel cell applications. Faceted Ir(210) is an excellent model catalyst for exploring structure sensitivity and size effects in surface chemistry. This is an abstract of a paper presented at the 228th ACS National Meeting (Philadelphia, PA 8/22-26/2004).
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