Controlled synthesis of mesoporous single-crystalline TiO₂ nanoparticles for efficient photocatalytic H₂ evolution

Mesoporous single-crystals have emerged as a unique family of functional materials, exhibiting excellent performance in various applications, owing to their well-defined accessible mesoporosity and highly single-crystalline structures. Precise tailoring structures of mesoporous single-crystals at the nanoscale remains an unsolved scientific and technical challenge. Herein, we report a facile and general approach for the synthesis of mesoporous single-crystalline TiO₂ nanoparticles (designated as MSC-TNs) with distinctive traits including tunable morphologies, controllable particle sizes, well dispersity, high hydrophilicity, well-defined mesoporosity and single-crystal nature. Specifically, the amount of water employed in the precursor solution was seen to give fine control over the particle sizes and morphologies of MSC-TNs. MSC-TNs with different sizes show excellent photocatalytic activity in production of hydrogen from water. Under the illumination of 300 W Xe lamp, MSC-TNs were shown to provide good photodegradation performance with Rhodamine 6 G, as well as H₂ production when loaded 1 wt % Pt. In a CH₃OH solution H₂ was evolved with a rate of 8.98 mmol h^-1 g^-1, which is significantly higher than with commercial P25 nanoparticles (4.02 mmol h^-1 g^-1).