Invited: Plasmaelectrochemistry in Ionic Liquids: Challenges to Make Silicon Nanoparticles

Based on the publications of J. Gubkin et al in the early 20th century we developped together with Juergen Janek the concept of plasmaelectrochemistry in ionic liquids (ILs). ILs have quite low vapour pressures that make them even ultrahigh vacuum compatible. Thus, a low temperature low pressure plasma can be ignited over an ionic liquid and the electrons of the plasma can be used as a reducing agent. By this way we could make several metals as nanoparticles and - interestingly - the particle sizes are in the regime between 10 and 50 nm, dependent on the IL and the experimental conditions. The making of Ge or Si (or SiGe) nanoparticles is complicated by the high vapour pressure of the respective precursors which at the reduced pressure of the plasma experiment are simply pumped off. With a specially designed cell this problem could be solved. It will be shown that Si nanoparticles can be made by plasmaelectrochemistry and that these particles are highly reactive, even against the employed ionic liquid, which makes the analysis a bit challenging (invited).