New galvanic plating processes from ionic liquids

The BMBF funded Reseach Network GALACTIF is a joint research project between six German Universities and research institution focussing on electrodeposition of selected metal and alloy layers from ionic liquids. Fundamentally new concepts shall be researched in order to establish the foundation for a cost competetive and environmentally friendly coating technology.

Due to their wide electrochemical potential window, ionic liquids (ILs) permit the electrodeposition of very unnoble materials. Hydrogen evolution as a side reaction does not occur. Further advantages of the ionic liquids are their low vapor pressure, the often low toxicity, and the non-flammability. A disadvantage compared to water is the much higher viscosity, that however strongly decreases already with small temperature increase. Metal ions with higher oxidation states are often reduced stepwise, where stable intermediates may be formed. The structure at the phase boundaries electrode / ionic liquid and the elemental processes of deposition are not explored to the same extent and those in aqueous solutions. In that regard, especially scanning probe microscopy techniques have shown large potential for researching these important properties, and resulted in first details of a rather complex interfacial structure. Since about ten years, the electrodeposition of refractory metals at moderate temperatures is under study, with an emphasis on titanium and tantalum. Also aluminium and noble metals have been studied.

TUM acts as the coordinator of the project. The partial project of TUM is entitled "Synthesis of new precursors and use of ultrasound for refractory metal deposition from ionic liquids". While the synthesis of new precursors is carried out at the Associate Professorship of Molecular Catalysis, in our group we focus on electrodeposition of refractory metals using different commercial precursor / ionic liquids combinations and study the effect of ultrasound application on it. In addition, we carry out the electrochemical characterisation of the precursors prepared by the colleagues from Chemistry Department.