Oxide-metal nanowires by oxidation of a one-dimensional Mn-Pd alloy: stability and reactivity.

Distinct one-dimensional (1D) oxide nanowires decorating the step edges of a stepped Pd(1 1 9) surface are formed by partial and complete oxidation of a 1D Mn-Pd alloy. Under full postoxidation treatment at 470-570 K, 1D MnO(2) nanowires coupled pseudomorphically to the Pd steps are obtained. Oxidized nanowires, which maintain the basic structural pattern of the 1D Mn-Pd alloy, are instead prepared by exposure of the Mn-Pd alloy to O(2) at 90 K and subsequent short heating to 400 K. A relatively weak Mn-O bonding characterizes these oxidized alloy wires, which are readily reduced by reaction with CO at moderate temperature (350 K). The here reported system emphasizes the influence of kinetic constraints in the formation of oxide nanostructures.