Hexafluorotitanic acid-assisted synthesis of large-sized, ultrathin titania nanosheets as multifunctional and high-performance photocatalysts.

A fast cyclohexanol solvothermal pathway was developed to prepare highly dispersed anatase titania (TiO2) nanosheets with an edge length of ∼800 nm and a thickness of ∼6 nm. Under the synergistic control of hexafluorotitanic acid and cyclohexanol, the exposed 001 facets reached ∼98.5% on the TiO2 nanosheets obtained by the treatment at 180 °C for 150 min. Moreover, it was found that the phase transformation and structural development drastically occurred during the solvothermal treatment. When used as a catalyst for photodegradation of rhodamine B, the TiO2 nanosheets exhibited a good recycling stability and a much higher photocatalytic degradation rate (nearly 99% degradation within 2.5 h) than the commercial P25 (93.6%). After being uniformly loaded with 4 wt.% of the Pt nanoparticles, the TiO2 nanosheets displayed a photocatalytic hydrogen production rate of 2.239 mmol g-1 h-1 under simulated solar light, which was much higher than the pristine TiO2 nanosheets (0.045 mmol g-1 h-1) as well as most of the reported TiO2-based photocatalysts. The remarkable photocatalytic activity and good stability of the TiO2 nanosheets with highly exposed 001 facets would make them find potential applications in both water treatment and hydrogen generation from water splitting under solar light.