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

Figure 4

Schematic illustration explaining the diffusion rate of ionic species at metal-oxide layers above the Ti foil, (a) Stage 1 (cool condition), (b) room temperature (27°C), and (c) Stage 2 (warm condition).

(a)

(b)

(c)