Island Ripening via a Polymerization-Depolymerization Mechanism

In catalytic methanol oxidation on ultrathin vanadium oxide layers on Rh(111) (Theta(V) approximate to 0.2 monolayer equivalent) we observe a 2D ripening of the VOx islands that is controlled by the catalytic reaction. Neighboring VOx islands move under reaction conditions towards each other and coalesce. The motion and the coalescence of the islands are explained by a polymerization-depolymerization equilibrium that is sensitive to gradients in the adsorbate coverages.