Figure 18.

Schematic of narrow‐band‐gap semiconductor/TiO₂ nanotube coaxial heterogeneous structural design (a). Top‐surface FE‐SEM and enlarged (inset) images of CdS electrodeposited onto TiO₂ nanotube arrays at –0.65 V (b), –0.70 V (c) and –0.75 V (d) (vs Ag/AgCl) representatively. SEM images of TiO₂ nanotubes (e) and ZnS–In₂S₃–Ag₂S@TiO₂ nanotubes (f). The band structures and the mechanism of electron transport for ZnS–In₂S₃–Ag₂S solid solution coupled with TiO_2–xS_x nanotubes film catalyst (g). (a–d) Reproduced with permission.229 Copyright 2010, American Chemical Society. (e–g) Reproduced with permission.234 Copyright 2012, Elsevier.