Second Order Dependence on the Surface Fraction of Pt in PtRu_adatom of the Oxidation of 2‑PrOH in Base

The electrooxidation of 2-PrOH in alkaline electrolyte is studied over a series of Pt-Ru adatom catalysts with controlled surface compositions as a function of potential and temperature. Multivariable analysis is used to determine both kinetic and thermodynamic parameters of interest. PtRu surfaces are found to be more active at low potentials than either Pt or Ru alone. At moderate overpotentials, Pt is the most active catalyst due to a surface blocking effect by Ru. A clear second order dependence on the surface fraction of Pt is determined, and a kinetic isotope effect suggest that both CH­(D) and OH­(D) bonds are broken before or during the rate-determining step for the electro-dehydrogenation of 2-propanol to acetone. Possible mechanisms that account for these observations are discussed.