Ti³⁺ Self-Doped Blue TiO₂(B) Single-Crystalline Nanorods for Efficient Solar-Driven Photocatalytic Performance

Ti 3+ self-doped blue TiO 2 (B) single-crystalline nanorods (b-TR) are fabricated via a simple sol–gelation method, cooperated with hydro-thermal treatment and subsequent in situ treatment method, and afterward annealed at 350 °C in Ar. The structures are characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (UV–vis), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The prepared b-TR with narrow band gap possesses single-crystalline TiO 2 (B) phase, Ti 3+ self-doping, and one-dimensional (1D) rodlike nanostructure. In addition, the improved photocatalytic performance is studied by decomposition of Rhodamine B (RhB) and hydrogen evolution. The degradation rate of RhB by Ti 3+ self-doped blue TiO 2 (B) single-crystalline nanorods is ∼6.9- and 2.1-times higher compared with the rates of titanium dioxide nanoparticles and pristine TiO 2 (B) nanorods under visible light illumination, respectively. The hydrogen evolution rate of b-TR is 26.6 times higher compared with that of titanium dioxide nanoparticles under AM 1.5 irradiation. The enhanced photocatalytic performances arise from the synergetic action of the special TiO 2 (B) phase, Ti 3+ self-doping, and the 1D rod-shaped single-crystalline nanostructure, favoring the visible light utilization and the separation and transportation of photogenerated charge carriers.