Influence of anodisation voltage on the dimension of titania nanotubes

The formation of self-organised titanium dioxide (TiO2) nanotubes array was achieved by anodisation of pure titanium foil in a standard two-electrode bath consisting of 1 M Na2SO4. Excess NH4F (5 wt%) was used in this work and the pH was kept constant at 3. Control over the dimension of the nanotubes was successfully established in this work by altering the anodisation voltage. Three important observations were made: (i) there is a threshold voltage above which nanotubes will form, (ii) within the range of voltages where nanotubes form, samples made at low voltage consist of nanotubes with small pore size (<40 nm) and nanotubes diameter increases with voltage until a maximum voltage of 25 V where the nanotubular array started to diminish and (iii) the length of the nanotubes also increases with anodisation voltage. Photocatalytic degradation of methylene blue (MB) was successfully performed on the titania nanotubes with diameter of 100 nm.