Rihab Al-Salman

Electrodeposition of 3D ordered macroporous germanium from ionic liquids: a feasible method to make photonic crystals with a high dielectric constant.

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.

Electrodeposition of Ge, Si and SixGe1−x from an air- and water-stable ionic liquid

The electrodeposition of Ge, Si and, for the first time, of Si(x)Ge(1-x) from the air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py(1,4)]Tf(2)N) containing GeCl(4) and/or SiCl(4) as precursors is investigated by cyclic voltammetry and high-resolution scanning electron microscopy. GeCl(2) in [Py(1,4)]Tf(2)N is electrochemically prepared in a two-compartment cell to be used as Ge precursor instead of GeCl(4) in order to avoid the chemical attack of Ge(iv) on deposited Ge. Silicon, germanium and Si(x)Ge(1-x) can be deposited reproducibly and easily in this ionic liquid. Interestingly, the Si(x)Ge(1-x) deposit showed a strong colour change (from red to blue) at room temperature during electrodeposition, which is likely to be due to a quantum size effect. The observed colours are indicative of band gaps between at least 1.5 and 3.2 eV. The potential of ionic liquids in Si(x)Ge(1-x) electrodeposition is demonstrated.

Semiconductor nanostructures via electrodeposition from ionic liquids

The fascinating properties of ionic liquids make it possible to synthesize semiconductor nanostructures via a simple and low-cost electrochemical pathway. The present paper summarizes our recent work on the synthesis of Si, Ge, and SixGe1–x nanostructures from ionic liquids: thin films, nanowires and photonic crystals. We also introduce our first results on the template-assisted electrodeposition of SixGe1–x photonic crystals from 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf2N) ionic liquid, and some optical measurements on the previously prepared Ge photonic crystals. Our results confirm that electrochemistry in ionic liquids is excellently suited to the synthesis of high-quality semiconductor nanostructures.

Highly Ordered 3D-Macroporous Poly(Para-Phenylene) Films Made by Electropolymerization of Benzene in an Ionic Liquid

Abstract A simple and efficient method for the preparation of highly ordered 3-dimensional macroporous polyparaphenylene (3DOM-PPP) conducting polymer films is reported for the first time. The method involves the simple electropolymerization of benzene inside a polystyrene opal template at mild reaction conditions. The ionic liquid 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIm]FAP) containing benzene as a precursor is used as the electrolyte. Polystyrene colloidal crystals with average sphere-diameters of 240, 370 and 600 nm on ITO-glass substrates were used as templates. The obtained PPP inverse opal structures showed strong blue, green, yellow and red colors due to light diffraction caused by the 3-D highly ordered macroporous structure. A complete filling of the PS template with PPP can be easily achieved at room temperature. The electrochemical process was investigated by cyclic voltammetry and the deposits were characterized by SEM and IR analysis.

Electrochemical Synthesis of Gallium Nanowires and Macroporous Structures in an Ionic Liquid

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 templates 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.