CO Chemisorption on Vicinal Rh(111) Surfaces Studied with a Curved Crystal

Curved crystal surfaces enable the systematic and accurate comparison of physical and chemical processes for a full set of vicinal crystal planes, which are probed in the very same environment. Here, we examine the early stages of the CO chemisorption on vicinal Rh(111) surfaces using a curved Rh crystal that exposes a smoothly variable density of {100} (A-type) and {111} (B-type) steps. We readily identify and quantify step and terrace species by resolving their respective core-level lines using X-ray photoelectron spectroscopy at different locations on the curved surface. Uptake experiments show similar sticking probabilities at all surface planes, subtle asymmetries between A- and B-type steps, and significantly lower saturation coverage at densely stepped surfaces as compared to the (111) plane. The analysis of the C 1s intensity variation across the curved sample allows us to discuss the adsorption geometry around the step edge.We acknowledge financial support from the Spanish Ministry of Economy (Grants MAT-2016-78293-C6, MAT-2017- 88374-P), Basque Government (Grant IT-1255-19), the VR funded Röntgen−Angström collaboration “Catalysis on the atomic scale” project number 349-2011-6491, and the Knut and Alice Wallenberg (KAW) funded project “Atomistic design of new catalysts” project number KAW 2015.0058