Is CO Oxidation a Structure-insensitive Reaction

Temperature-programmed reactions between small amounts of adsorbed species are an excellent way to study the intrinsic reactivity of catalytic surfaces. Such experiments on rhodium (100) and (111) surfaces covered by small amounts of CO and 

O showed a profound difference in CO2 formation rate [M.J.P. Hopstaken and J.W. Niemantsverdriet, J. Chem. Phys. 113 (2000) 5457]. Hence, care should be taken to interpret apparent structure sensitivity found under normal operating conditions of high pressure and coverage in terms of the intrinsic reactivity of sites. From the theory of chemisorption and reaction discussed in Chapter 6 it is hard to imagine how the concept of structure insensitivity can be maintained on the level of individual sites on surfaces, as atoms in different geometries always possess different bonding characteristics. 

---