Fabrication, Modification, and Emerging Applications of TiO₂ Nanotube Arrays by Electrochemical Synthesis: A Review

Figure 4

Schematic of energy level of pure TiO₂ (a) and corresponding modification ((b)–(d)). (b) Doping or dye-sensitization, semiconductors (c), and noble metals (d) coupling.

(a)

(b)

(c)

(d)