Photoelectrochemical Performance of Smooth TiO₂ Nanotube Arrays: Effect of Anodization Temperature and Cleaning Methods

Figure 8

FESEM images of TiO₂ nanotubes obtained via chemical etching using 2% HF after anodization for (a) 10, (b) 15, (c) 20, and (d) 60 s.

(a)

(b)

(c)

(d)