ABSTRACT
The formation of well-ordered titania nanotubes is achieved by electrochemical anodisation under specific experimental conditions. In the present work, the formation of titania nanotubes on titanium substrates is investigated in two different electrolytes: Na2SO4 and (NH4)2SO4. The amount of fluoride was varied from 0.5 to 5 wt%. Scanning electron microscope (SEM), X-Ray diffraction (XRD), and Energy Dispersive X-ray (EDX) surface analyses were carried out to characterise the wellordered titania nanotubes. The results show that the composition of electrolytes drastically influenced the final morphology of the titania nanotubes. Titania nanotubes with various diameters in the range of 20–100 nm and lengths of 0.3–0.7 μm were obtained by tailoring the electrochemical conditions during titanium anodisation. From the SEM images, it was evident that the well-ordered regular porous structure consists of pore arrays with a uniform pore diameter. It was also clear that pore mouths were opened on the top of the layer, while the tubes were closed by the presence of a layer of titania on the bottom of the structure. Here in, we discuss the influence of different electrolyte compositions on the structure of well-ordered titania nanotubes in detail. We furthermore show that the nanotubes consist of titania and that they remain unchanged when annealed.
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