Metal and semiconductor nanostructures are usually synthesized using vacuum techniques. Such processes are cost-intensive and need vacuum conditions for preparation thus making the semiconductors quite expensive. Electrodeposition is an alternative and relatively simple way to produce these materials. However for electrochemical synthesis, applying of a proper solvent is essential to produce metals and semiconductors. The electrodeposition from aqueous solutions is limited by a relatively low electrochemical stability of water. In the case of molten salts, high temperature is usually required for electrodeposition. Organic solvents are very volatile and many of them are quite toxic. The alternative to common electrolytes is to use ionic liquids (ILs), which exhibit wide electrochemical windows, good thermal stability, non-volatility, low toxicity and are liquid below 100 °C [1].

In this lecture we will show that ILs are well suited for the electrodeposition of metal and semiconductor nanostructures with various architectures. Consequently, metal (e.g. Ga, In, Zn, Al, Cu, etc.) and semiconductor (Si, Ge, Si_xGe_1‑x, etc.) nanowires, nanotubes and macroporous structures can be synthesized in ILs at room temperature by using template-assisted electrodeposition. Recently, these materials have received some attention as promising electrode materials in batteries [2]. Furthermore, III‑V semiconductor (e.g. GaSb and InSb) nanowires can be directly synthesized at room temperature by electroless deposition [3]. Some nanowires (e.g. ZnS) can be obtained in ILs without any external template, which opens a new perspective for the synthesis of semiconductor nanostructures. The structure of the IL/electrode interface can significantly alter the deposition process that, in turn, may result in the deposits with various morphologies and properties. This offers the opportunity to influence the optical properties of obtained materials by changing the composition of the solvent.

[1] F. Endres, A. Abbott, D. R. MacFarlane, Electrodeposition from Ionic Liquids. 2^nd Edition. 2017, Weinheim: Wiley‑VCH Verlag GmbH & Co. KGaA.

[2] M. Shapouri Ghazvini, G. Pulletikhurthi, Z. Liu, A. Prowald, S. Zein El Abedin, F. Endres, J. Solid State Electrochem., 19 (2015) 1453‑1461.

[3] A. Lahiri, N. Boriseko, M. Olschewski, R. Gustus, J. Zahlbach, F. Endres, Angew. Chem. Int. Ed., 54(40) (2015) 11870‑11874.