In-situ C-N-S-tridoped single crystal black TiO2 nanosheets with exposed {001} facets as efficient visible-light-driven photocatalysts

In-situ C-N-S-tridoped single crystal black TiO 2 nanosheets with exposed {001} facets are successfully fabricated via a facile hydrothermal method combined with an in-situ solid-state chemical reduction approach, followed by calcination at 450   °C. The crystal structure, crystallinity, morphology and composition of the as-prepared samples are investigated through X-ray diffraction, Raman, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy, respectively. The results suggest that the obtained C-N-S-tridoped single crystal black TiO 2 nanosheets exhibit uniform nanosheet-like structure with exposed {001} facets and average length of ∼300–400   nm, thickness of ∼20   nm. The visible-light photocatalytic degradation rate of methyl orange is up to 92.13%, and photocatalytic hydrogen evolution is 149.7   μmol   h −1   g −1 . The excellent photocatalytic activity can be ascribed to the synergetic effect of surface heterojunction between {001} and {101} facets, the C-N-S-tridoping, and the formed Ti 3+ species in photocatalyst, which can not only favor the visible-light absorption but also facilitate the separation and transfer of photogenerated charges.