The cross-sectional structure of vanadium oxide nanotubes studied by transmission electron microscopy and electron spectroscopic imaging

Vanadium oxide nanotubes (VOx-NTs) are easily accessible in pure form from vanadium(V) alkoxides and amines by a sol-gel reaction and a subsequent hyd rothermal treatment. The wall structure of VOx-NTs containing hexadecylamin e or dodecylamine as the structure-directing template has been characterise d by transmission electron microscopy (TEM). A standard method for preparin g TEM specimens was modified in order to investigate the cross-sectional st ructure of the tubes. The elemental distribution in the layered structure i nside the tube wails has been visualised by electron spectroscopic imaging: vanadium oxide builds up the layers that appear with dark contrast in the TEM images while carbon, i.e., the organic template, is present in between. The bent VOx layers inside the tube walls are preferentially scrolls rathe r than concentric cylinders. Moreover, some tubes are formed by a combinati on of both types. The layer structure inside the tube walls is frequently d isordered, and several types of defects appear.