Before moving on to bimetallic surfaces we would like to comment on the fact that the Sabatier For bimetallic surfaces, the simplest picture would expect a specific rate for each type of active site or better active ensemble, which is determined by the respective bond strength on this site. In this case the total reaction rate R would be given by the sum of the products of the number of the respective active site ni times the rate ri on this site, which is given by the relevant binding energy on this site