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 GeS_x 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 GeS_x colloidal particles assembled in a three-dimensional architecture. A detailed comparison of GeS_x 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 GeS_x is oxidized to a crystalline phase identified by X-ray photoelectron spectroscopy, Raman spectroscopy and PXRD cell refinement to be hexagonal GeO₂.