ABSTRACT
The electrochemical synthesis of gallium nanostructures in an ionic liquid is presented. Gallium nanowires and macroporous structures were synthesized by the template-assisted electrodeposition in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py(1,4)]TFSA) containing GaCl(3) as the precursor. Track-etched polycarbonate membranes with an average pore diameter of 90 nm and a thickness of 21 µm were used as templates for the nanowire synthesis. Ga nanowires with a length of more than 4 µm and an average diameter corresponding to that of the template's pores were easily obtained by this method. Macroporous structures with an average pore diameter of 600 nm were obtained by the electrochemical deposition of Ga inside polystyrene colloidal crystal templates and the subsequent removal of the template by THF. The macroporous deposit showed a granular morphology with smallest grain sizes of about 40 nm and light reflections. The nanostructures of Ga were characterized by HR-SEM and EDX analysis.
ABSTRACT
In this discussion paper we discuss our recent results on the electrodeposition of materials and in situ STM/AFM measurements which demonstrate that ionic liquids should not be regarded as neutral solvents which all have similar properties. In particular, we focus on differences in interfacial structure (solvation layers) on metal electrodes as a function of ionic liquid species. Recent theoretical and experimental results show that conventional double layers do not form on metal electrodes in ionic liquid systems. Rather, a multilayer architecture is present, with the number of layers determined by the ionic liquid species and the properties of the surface; up to seven discrete interfacial solvent layers are present on electrode surfaces, consequently there is no simple electrochemical double layer. Both the electrodeposition of aluminium and of tantalum are strongly influenced by ionic liquids: in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py(1,4)]TFSA, aluminium is obtained as a nanomaterial, whereas in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [EMIm]TFSA, a microcrystalline material is made. Tantalum can be deposited from [Py(1,4)]TFSA, whereas from [EMIm]TFSA only non-stoichiometric tantalum fluorides TaF(x) are obtained. It is likely that solvation layers influence these reactions.
ABSTRACT
A promising method for the production of germanium photonic crystals consists of electrodeposition of Ge from GeCl(4)-containing ionic liquids inside templates of polystyrene colloidal crystals and subsequent removal of the template. This room-temperature method gives rise to the fabrication of a three-dimensional highly ordered macroporous germanium nanostructure (see picture; scale: 2 microm) as a prototype of a photonic crystal.
