Roadmap for Modeling RhPt/Pt(111) Catalytic Surfaces

PtRh alloys are used as versatile multipurpose catalysts for a number of industrial applications, including fertilizer production and ammonia slip catalysts for NOx abatement purposes. For the latter, ammonia is oxidized to nitrogen at intermediate temperatures. To optimize the PtRh-alloyed catalysts and explain the role of Pt and Rh for future intermediate-temperature ammonia oxidation operando studies, we prepared a series of distinct RhPt model surfaces. We explore postannealing and high-temperature deposition as two routes for preparation of surface alloys and compare results with literature examples. Scanning tunneling microscopy and X-ray photoelectron spectroscopy provide detailed information on surface morphology and composition and demonstrate excellent temperature stability of RhPt/Pt(111) in the temperature range targeted for operando catalytic studies. A detailed roadmap summarizes preparation conditions to achieve a broad variety of surface structures.