Abstract

TiO₂ photocatalysts doped with three transition metal ions of varying concentration were prepared by adsorption phase synthesis. The influence of different metal ion species and contents on the morphology and crystallization of TiO₂ sintered under various temperatures was explored by transmission electron microscopy, X-ray diffractometry, UVvis spectroscopy, and X-ray photoelectron spectroscopy. Photodegradation experiments on methyl-orange were employed to evaluate photocatalytic activity. Results indicated that 0.05 at.% Fe³⁺ and Cd²⁺ doping introduces lattice distortions as shallow trapping sites; moreover, doping improved the activity of adsorption phase synthesis (APS) catalysts. TiO₂ crystallization was restricted when the doping content was greater than 0.05 at.% because other metal ions destroy the TiO₂ lattice structure. Restriction also increased with doping content. An optimum doping content was observed during the preparation of TiO₂ doped with Cd²⁺ and Fe³⁺. As the Fe³⁺ radius is close to the Ti⁴⁺ radius, the influence of Fe³⁺ doping content on TiO₂ crystallization and activity was more apparent than that of Cd²⁺ doping content. Increases in sintering temperature resulted in fewer lattice distortions acting as shallow trapping sites and decreases in APS catalyst activities.

Keywords: Adsorption phase synthesis, methyl-orange, photodegradation, transition metal ions doping, TiO₂.

Graphical Abstract