Effects of Ni Doping and Silica Gel Bead Support on Characteristics of TiO2 Catalyst.

Titanium dioxide (TiO₂) photocatalyst is an excellent solution that can be utilized to decompose organic pollutants. In this report, Ni-doped TiO₂ immobilized on silica gel bead by sol–gel process was investigated. The morphology, crystal phase composition, particle size, porosity characteristics, and optical properties of the samples were investigated through scanning electron microscopy, high-resolution transmission electron microscopy, x-ray diffraction, N₂ isothermal loops, Raman spectroscopy, and ultraviolet–visible (UV–Vis) absorption. The results revealed that Ni²⁺ uniformly distributed in the TiO₂ crystal lattice to replace Ti⁴⁺ and that Ni²⁺ did not change the TiO₂ anatase crystal phase. Compared with pure TiO₂, the absorption edge of the Ni-doped TiO₂ sample exhibited a redshift from 400 nm to 655 nm. Influenced by silica gel bead as catalyst support, the crystal size of Ni-doped TiO₂ sample was reduced from 27 nm to 6 nm that led to a blueshift in both Raman and UV–Vis spectra. The photocatalytic enhancement was demonstrated by methyl orange decomposition. Under ultraviolet irradiation, the photocatalytic performance of Ni-doped TiO₂ immobilized on silica gel bead was lower compared with pure sample. Opposite to this, Ni-doped TiO₂ immobilized on silica gel bead showed photocatalytic enhancement under visible light. [ABSTRACT FROM AUTHOR]