Scheme 1

Light absorption and carrier charge transport in (a) 2D TiO₂ film; (b) untreated 3D TiO₂ nanorods and (c) 3D H-TiO₂ nanorods, the outmost disordered shell is drawn with black line and the enhanced light scattering is marked with thick arrows. Relation between the diameter d of nanorods and the depletion region width W: (d) d > > W; (e) d > W and (f) d ~ W