A HREELS study of the effect of Cu on the interaction of HCOOH with ZnO(000(1)over-bar)-O

The modifying properties of Cu overlayers on the interaction of formic acid with ZnO(000 (1) over bar)-O have been investigated by HREELS at 300 K. Copper modifies the HREELS spectrum in a manner consistent with initial nucleation at defect sites to form two-dimensional islands at a coverage of less than one monolayer, with three-dimensional islands formed at higher coverages. Formic acid adsorption on Cu overlayers appears to result in a bridging bidentate formate species on terrace sites as well as the formation of tilted species at defect sites or island edges. Formic acid decomposition is proposed to occur at the Cu/ZnO interface, resulting in the chemisorption of CO at exposed Zn2+ sites around the island perimeter. (C) 1998 Elsevier Science B.V. All rights reserved.