Atomic layer deposition of ZnO on Cu-nanoclusters for methanol synthesis

The properties of ALD-grown ZnO thin films on Cu clusters supported on ZnO(101¯0) have been studied with scanning tunneling and scanning electron microscopy in combination with angle-resolved x-ray photoelectron spectroscopy. Deposition at room temperature of two monolayers of Cu on ZnO(101¯0) results in metallic Cu0 clusters ∼8 nm wide by 1.4 nm high. Higher coverages of 15 ML results in a similar morphology, with slightly larger cluster sizes. Following air-exposure and ALD-growth of two cycles of ZnO, the Cu exhibits Cu+ species characteristic of Cu2O and the thin ZnO coating is hydroxylated. Electrochemical studies of ALD ZnO coatings on Cu suggest that they are more active for CO2 reduction.