Hydrothermal Synthesis, Photocatalytic Performance, and Phase Evolution from BiOCl to Bi2Ti2O7 in the Bi-Ti-Cl-O System

In this work, the influence of annealing treatment on the phase evolution and photocatalytic behavior in a Bi-Ti-Cl-O system prepared by a hydrothermal method was investigated. The crystal structure, particle surface morphology, and absorption properties of the samples were characterized by x-ray diffraction, field emission scanning electron microscopy, and UV–Vis diffuse-reflectance spectroscopy, respectively. The transformation process was found to occur in three stages, involving BiOCl, Bi2Ti2O7/BiOCl composite, and Bi2Ti2O7 phases, with increasing annealing temperature. The photocatalytic activity of the samples was evaluated through photodegradation of Rhodamine B under simulated sunlight irradiation. It was found that the photocatalytic activity of Bi2Ti2O7/BiOCl nanocomposites is greater than that of BiOCl or Bi2Ti2O7. The enhanced photocatalytic activity of the Bi2Ti2O7/BiOCl nanocomposite could be attributed to the effective separation of electron–hole pairs.