RETRACTED: Enhanced photocatalytic degradation of 4-chlorophenol by Zr4+ doped nano TiO2

Abstract

Abstract Zr 4+ doped nano titania was prepared by sol–gel method using titanium(IV) isopropoxide and zirconium nitrate as precursors. The materials were characterized by XRD, BET, UV–vis, FT-IR, SEM-EDX and TEM techniques. The nanoparticles of pure TiO 2 contained both anatase and rutile phases together but Zr 4+ doped TiO 2 gave anatase phase only. The framework substitution of Zr 4+ in TiO 2 was established by XRD, SEM-EDX and FT-IR techniques. The band gap value of Zr 4+ doped TiO 2 was higher than the parent nano TiO 2 . TEM observations confirmed the nanocrystalline nature of Zr 4+ doped TiO 2 . The presence of dopants therefore could suppress the growth of TiO 2 grains, increase the surface area, decrease the anatase–rutile phase transformation and accelerate the surface hydroxylation. These properties resulted higher photocatalytic activity for Zr 4+ doped nano TiO 2 than undoped nano TiO 2 . The presence of anatase type structure in TiO 2 with high crystallinity and high phase stability, even after annealing at 800 °C substantially indicated that the dopants might inhibit densification and crystallite growth by providing dissimilar boundaries. The photocatalytic activity in the degradation of 4-chlorophenol was found to be higher for Zr 4+ doped TiO 2 than both nano TiO 2 and commercial TiO 2 (Degussa P25). The experimental parameters such as initial concentration of 4-chlorophenol, catalyst loading, pH and light intensity were optimized for maximum degradation efficiency.