The modifications of copper work function by layer-by-layer deposition of [W(CN)8]4− – Co2+ bimetallic nanolayers

In the reaction of K4[W(CN)8] · 2H2O and Co2+(aq) cations on the polycrystalline or monocrystalline [3 1 1] copper using layer-by-layer deposition, a thin film of the coordination polymer {[{Co(H2O)2(μ-CN)4}2W] · 4H2O}n was formed. The work function of copper and deposited on it bi-layers depended on a number of layers and the concentrations of the deposited precursors. At high complex concentrations work function reached the plateau after several deposition processes, while at low concentrations oscillations in the work function were observed when K+ or Co2+ cations were present in the outside layer. The changes of the work function were also dependent on Co2+ salt used (CoCl2 · 6H2O or Co(NO3)2 · 6H2O). This was interpreted in terms of a layer structure resulting from various coordination of external anions to cobalt cations.

Graphical abstractThe layer-by-layer deposition of a [W(CN)8]4−/Coaq2+ on a monocrystalline [3 1 1] and polycrystalline copper resulted in the work function change by 0.4 eV at ca. 3 nm layer thickness. The work function change was then independent of layer thickness up to 40 nm. At the low amount of [W(CN)8]4− ion in solution, deposited layers did not cover totally the copper surface and oscillations in the work function change were observed. The oscillation depended on anion used (Cl− or NO3-) and number of layers deposited. After total surface coverage work function change reached plateau.Figure optionsDownload full-size imageDownload as PowerPoint slide