Clean TiO₂ nanocuboid film tightly attached on a conductive substrate for highly efficient photoelectrochemical water splitting

Anatase TiO₂ film consisting of nanocuboids with co-exposed {1 0 1}, {0 0 1} and {1 0 0} facets have been successfully synthesized via thermally annealing amorphous anodized TiO₂ nanotube arrays in ambient fluorine. When employed as a photoanode material in photoelectrochemical water splitting, the film of the clean TiO₂ nanocuoboids yields a photocurrent density of up to 0.65 mA cm⁻² at 0.22 V versus the Ag/AgCl electrode with Faradic efficiency of 100% and exhibits excellent stability, which can be attributed to enhanced photogenerated charge separation and transport to the collecting electrode. This film could also potentially be used for other facet-related applications such as TiO₂ based dye-sensitized solar cells, sensors and lithium batteries. (letter)