NO2 gas adsorption on titania-based nanotubes

T1O2-based nanotubes were prepared using a hydrothermal technique and then investigated by high-resolution TEM. Nanotubes were found to be hollow scrolls with a typical outer diameter of about 10 nm, inner diameter 4-5 nm and length of several hundred nm. The surface of nanotubes is found to be largely hydrolised. The presence of surface OH groups also determines their adsorption properties for the NO2 gas molecules. We demonstrate that TiO2 based nanotubes strongly adsorb NO2 molecules. Based on pulsed EPR experiments we suggest that the NO2 molecules couple with the nanotube surface via the nonbonding p(y) orbital of the oxygen atoms.