Hydrazine network on Cu(111) surface: A Density Functional Theory approach

摘要

We have used first-principles calculations, including a correction for the dispersive forces (DFT-D2), to investigate the arrangement of hydrazine (N2H4) molecules upon adsorption on the Cu(111) surface, showing that surface-molecule interactions affect the process most Our calculations provide insight into the interplay between lateral adsorbate-adsorbate and vertical adsorbate-substrate interactions. We found that the main contributors to the assembly of the hydrazine layers are the binding interactions between the adsorbates and the substrate. The-dispersion forces are predominant in both vertical and lateral interactions, whereas hydrogen-bonding is least important and organisation of the N2H4 monolayers is therefore primarily due to the long-range interactions. Optimised geometries for several hydrazine conformations were found to be coverage-dependent. The electronic properties such as charge density and density of states have been calculated for different hydrazine coverages, and indicated that no charge transfer occurs between molecules. Scanning tunnelling microscopy images were simulated, where the observed protrusions arise from the trans conformers. We also found that the effect of hydrazine adsorption on the Cu(111) surface energy is negligible and further investigation of other Cu facets is needed to determine the N2H4 effect on the nanoparticles' morphology. Finally, we have simulated the temperature programmed desorption of different coverages of hydrazine from the Cu(111) resulting in desorption peaks between 150 and 200 K. (C) 2015 Published by Elsevier B.V.