Reactive phase of oxygen on Cu(100) at 100 K studied by HREELS and TPD

The reactivity of oxygen adatoms formed by dissociative adsorption of oxygen at 100 K on Cu(100) for CO oxidation was investigated by means of HREELS and TPD in comparison with the reactivity of adsorbed oxygen in thermally stable phases. On Cu(100) covered with oxygen adatoms formed at 100 K, designated as oxygen-as-exposed surface, post-dosed CO was oxidized at 125 K in TPD. On annealing the as-exposed surface to 300 K, a change in the loss feature of v(Cu-O) was observed, indicating the formation of mixed phases comprised of pseudo c(2 × ·2)-O with O(a) in fourfold hollow sites and View the MathML source with CuO chains along the [001] direction. On these two phases, CO2 formation in TPD was reduced to one-ninth as compared to that on the as-exposed surface. These results may provide a new insight into the adsorbed phase of surface oxygen active for oxidation reaction and a way to develop a promising catalytic material with Cu metal.