Highly crystalline anatase TiO₂ nanocuboids as an efficient photocatalyst for hydrogen generation

Highly crystalline anatase titanium dioxide (TiO₂) nanocuboids were synthesized via a hydrothermal method using ethylenediamine tetraacetic acid as a capping agent. The structural study revealed the nanocrystalline nature of anatase TiO₂ nanocuboids. Morphological study indicates the formation of cuboid shaped particles with thickness of ∼5 nm and size in the range of 10-40 nm. The UV-visible absorbance spectra of TiO₂ nanocuboids showed a broad absorption with a tail in the visible-light region which is attributed to the incorporation of nitrogen atoms into the interstitial positions of the TiO₂ lattice as well as the formation of carbonaceous and carbonate species on the surface of TiO₂ nanocuboids. The specific surface areas of prepared TiO₂ nanocuboids were found to be in the range of 85.7-122.9 m² g^-1. The formation mechanism of the TiO₂ nanocuboids has also been investigated. Furthermore, the photocatalytic activities of the as-prepared TiO₂ nanocuboids were evaluated for H₂ generation via water splitting under UV-vis light irradiation and compared with the commercial anatase TiO₂. TiO₂ nanocuboids obtained at 200 °C after 48 h exhibited higher photocatalytic activity (3866.44 μmol h^-1 g^-1) than that of commercial anatase TiO₂ (831.30 μmol h^-1 g^-1). The enhanced photoactivity of TiO₂ nanocuboids may be due to the high specific surface area, good crystallinity, extended light absorption in the visible region and efficient charge separation.