Low-pressure methanol oxidation over a Cu(110) surface under stationary conditions: (II) adsorbate coverages and reactivity

The kinetics of methanol oxidation on a Cu(110) surface have been followed under stationary reaction conditions in the 10−7 to 10−5 mbar range with low-energy electron diffraction, Auger electron spectroscopy, photoelectron emission microscopy, and rate measurements. A large, 300-400 K-wide hysteresis occurs with cycling of the temperature. The (5×2) and c(2×2) structures, attributed to intermediates of the reaction, are seen only in a T-interval from 300 to ≈380K, where the reaction ignites. The surface exhibits substantial carbon coverage upon heating, but on the cooling branch the surface is largely carbon free down to ≈400K, where the surface becomes covered by C-containing adsorbates again.