How different dopants leads to difference in photocatalytic activity in doped TiO2?

Abstract

This study explores the significance of dopant location in a doped TiO2 nanostructure in ascertaining its photocatalytic properties. The un-doped TiO2, boron-doped TiO2 (B–TiO2) and nitrogen-doped TiO2 (N–TiO2) photocatalysts were synthesized (with variable dopant concentrations) via sol-gel method. The photocatalysts were further characterized for structural, surface, and physico-chemical properties in reference to their influence on photocatalytic properties. The results of X-ray diffraction (XRD), micro Raman, Energy dispersive X-ray technique (EDX), X-ray photoelectron spectroscopy (XPS), and Fourier Transform infrared spectroscopy (FTIR) confirmed the existence of B and N atoms in the TiO2 crystal lattice. The results also indicated that the B and N doping promoted the formation of rutile phase in doped TiO2. Further, B doping leads to decrease in the surface area whereas N doping leads to increase in surface area of TiO2. The UV–Vis DRS analysis revealed that a red shift in absorption band edge occurs upon B and N doping. The band gap values also decreased to 2.96 and 2.27 eV in B–TiO2 and N–TiO2, respectively in comparison to 2.98 for un-doped TiO2. The photocatalytic degradation studies of diclofenac sodium (DCLF) were conducted to examine the effect of dopant role on the efficiency of doped photocatalyst. B–TiO2 exhibited maximum photocatalytic activity by degrading 98% of DCLF in comparison to N–TiO2, which showed 95% degradation.