Synthesis and characterization of germanium sulfide aerogels

The synthesis of germanium sulfide gels by thiolysis reactions of a non-aqueous solution of Ge(OEt)4, followed by supercritical fluid extraction to create aerogels, is described. Analysis of the as-prepared GeSx aerogels by powder X-ray diffraction (PXRD) and surface area analysis reveals an amorphous structure exhibiting very high surface areas, 755 m2/g, that rival those of the best SiO2 aerogels when compared on a per mole basis. Transmission electron microscopy shows that the aerogel material is composed of a continuous network of GeSx colloidal particles assembled in a three-dimensional architecture. A detailed comparison of GeSx aerogels and their xerogel (bench-top dried) counterparts in terms of the influence of the synthetic methodology on morphology and surface area is reported. In the presence of adventitious moisture, the amorphous GeSx is oxidized to a crystalline phase identified by X-ray photoelectron spectroscopy, Raman spectroscopy and PXRD cell refinement to be hexagonal GeO2.