Iron-doped aluminogermanate nanotubes were obtained using a single step, aqueous phase synthesis protocol, resulting in a novel nanomaterial.

The synthesis protocol for Ge-imogolite (aluminogermanate nanotubes) consists of 3 main steps: base hydrolysis of a solution of aluminum and germanium monomers, stabilization of the suspension and heating at 95 °C. The successful synthesis of these nanotubes was found to be sensitive to the hydrolysis step. The impact of the hydrolysis ratio (from n_OH/n_Al = 0.5 to 3) on the final product structure was examined using a combination of characterization tools. Thus, key hydrolysis ratios were identified: n_OH/n_Al = 1.5 for the formation of nanotubes with structural defects, n_OH/n_Al = 2 for the synthesis of a well crystallized Ge imogolite and n_OH/n_Al > 2.5 where nanotube formation is hindered. The capability of controlling the degree of the nanotube's crystallinity opens up interesting opportunities in regard to new potential applications.

Short-term, aqueous aging of a commercial nanocomposite TiO ₂ UV filter with a protective SiO ₂ shell was examined in abiotic simulated fresh- and seawater.

Ge-imogolite nanotubes (Al₂GeO₇H₄) can be readily obtained in various lengths, chemical compositions and crystallinities, opening up new perspectives for applications. Their classical synthesis includes the nucleation of roof-tile shaped precursors at room temperature followed by a heat promoted growth (typically 95 °C) for at least 4 to 7 days. To circumvent this excessively long synthesis duration, we used microwave assisted heating to accelerate the growth. Micron sized tubes were formed from 1 h at 100 °C, and the best results were obtained for 2 hours at 200 °C, i.e. approximately 100 fold faster when compared to the conventional heating process. Additionally, tube lengths were shifted towards larger values by one order of magnitude, leading to micron sized Ge-imogolites vs. 100 nm with conventional heating. Specific microwave effects as well as mechanisms leading to these longer tubes are also discussed.