Synthesis of N-codoped TiO₂ via sonochemical method for degradation of CI Reactive Black 5

The use of ultrasound as a facile means for synthesis of titania-based photocatalysts is attractive and has been subjected to intense research. In this study, both nitrogen and chlorine were successfully doped into TiO₂ (N,Cl-codoped TiO₂) via sonochemical method using titanium(IV) butoxide and ammonium chloride as precursors. The physicochemical properties and morphology of the synthesized photocatalysts were examined by using characterization methods such as ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, X-ray diffraction (XRD), N₂ adsorption-desorption analysis and field emission scanning electron microscopy (FESEM). When tested on the degradation of CI Reactive Black 5, it was demonstrated that the photocatalytic activity exhibited by N,Cl-codoped TiO₂ was greatly affected by the synthesis conditions used. Increasing the sonication amplitude or duration up to a certain point shifted the absorption onset towards a lower energy and improved the crystallinity of the synthesized photocatalyst. It was also found that increasing N,Cl: TiO₂ molar ratio to 1.5 and conducting the synthesis in acidic conditions significantly enhanced the photocatalytic activity of N,Cl-codoped TiO₂. The highest degradation of RB5 of 98.3% was obtained by the N,Cl-codoped TiO₂ using sonication amplitude, sonication duration, N,Cl: TiO₂ molar ratio and synthesis pH of 50%, 180 min, ratio of 1.5 and pH 3.5, respectively.