Anatase TiO₂ sheet-assisted synthesis of Ti³⁺ self-doped mixed phase TiO₂ sheet with superior visible-light photocatalytic performance: Roles of anatase TiO₂ sheet

On the basis of measurements, such as field emission scanning electron microscope, UV–Vis diffuse reflectance spectra, X-ray diffraction, electron paramagnetic resonance, photoluminescence spectra, and photocurrent measurements, the roles of anatase TiO₂ sheet on synthesizing Ti³⁺ self-doped mixed phase TiO₂ nanosheets (doped TiO₂ (A/R, TiO₂ (A))) and on improving the performance for photocatalytic CO₂ reduction were explored systematically. High surface area anatase TiO₂ nanosheets (TiO₂ (A)) as a substrate, structure directing agent, and inhibitor, mediated the synthesis of Ti³⁺ self-doped mixed phase TiO₂ nanosheets. Addition of TiO₂ (A) significantly improved not only visible light absorption of doped TiO₂ (A/R, TiO₂ (A)), but also the efficiency of photo-excited charges separations due to the existence of interfacial regions of anatase-rutile TiO₂ junctions. Finally, a possible mechanism for interfacial charge transfer at the anatase-rutile TiO₂ interface and for photocatalytic CO₂ reduction over Pt loaded doped TiO₂ (A/R, TiO₂ (A)) were proposed.