Comparison between microwave and muffle annealing of self-organized TiO2 nanotubes into crystalline anatase

Abstract For the first time, the electrical and morphological properties of self-organized TiO 2 nanotubular samples annealed (for only 2 min) in a microwave oven through hybrid thermal heating (MO–TiO 2 ) are assessed comparatively to those of samples conventionally annealed (for 30 min) in a muffle furnace (MF–TiO 2 ). This comparative assessment was carried out through scanning electron micrographs, cyclic voltammetry and photocurrent density curves, as well as determinations of band-gap energy, donor density, and flat-band potential values. No differences in bang-gap energy and morphology were observed; MO–TiO 2 presented a small improvement in the donor density value, which, however, did not lead to higher photocurrent densities in comparison to MF–TiO 2 . Hence, considering that the morphological and electrical properties of the differently annealed TiO 2 nanotubular samples are similar, clearly microwave annealing is an advantageous option to convert amorphous TiO 2 nanotubes into the crystalline anatase phase, especially because this procedure is very rapid and facile.