Hydrogen Oxidation on Stepped Rh Surfaces: µm-Scale versus Nanoscale

The catalytic H 2 oxidation reaction on stepped Rh surfaces in the 10 −6 mbar pressure range was studied in situ on individual high-Miller-index domains of a polycrystalline Rh foil by PEEM (photoemission electron microscopy) and on a Rh nanotip by FIM/FEM (field-ion/field-emission microscopy). The activity, particularly the tolerance to poisoning by oxygen, was found to strongly depend on the density of steps and defects, as well as on the size of the catalytically active surfaces. Graphical Abstract