**2. Synthesis routes to nanostructured titanium dioxides (mesostructure spherical nanoparticles, nanotubes)**

Firstly, mesostructured titania as photoanodes for photoelectrochemical solar cells that are famously called dye-sensitized solar cells (DSSC) is discussed. Hydrothermal-seeded protocol is offered as a recommended synthesis route to achieve the targeted photoactivity. Secondly, one-dimensional nanostructured titania is proposed for the photoanodes. Nanotube titania was synthesized through templated-hydrothermal method and has shown improved photoactivity than that of nanoparticles. Sonication is proposed to shorten the synthesis time to prepare nanotube titania.
