Study on nanomagnets supported TiO₂ photocatalysts prepared by a sol-gel process in reverse microemulsion combining with solvent-thermal technique

A sol-gel process in reverse microemulsion combined with solvent-thermal technique was developed for synthesizing a series of nanomagnets supported TiO₂ (TiO₂/NMs) photocatalysts in this study. The structure of TiO₂/NMs photocatalysts was characterized by Fourier transform infrared (FTIR), TG-DSC, X-ray diffraction (XRD), Raman spectrometry, TEM, BET, and VSM. The influence of CoFe₂O₄ dosage on the photocatalytic activity and magnetism of TiO₂/NMs photocatalysts was investigated. The results showed that nanosized anatase TiO₂ were uniformly coated on spinel CoFe₂O₄ in the prepared TiO₂/NMs photocatalysts. They possessed typical ferromagnetic hysteresis and performed better photocatalytic activity in degradation of methylene blue than TiO₂ prepared by the same method. The existence of CoFe₂O₄ nanomagnets played an important role on the crystalline grain size of TiO₂ and the specific surface area of the prepared TiO₂/NMs photocatalysts, thus had an important influence on its photocatalytic performance and magnetism. The photocatalytic performance of TiO₂/NMs photocatalysts is related to their specific surface area, crystalline grain sizes of TiO₂ and particle size, as well as the doping effect of Fe³⁺. The highest photocatalytic activity in degradation of methylene blue for TiO₂/NMs photocatalysts at the CoFe₂O₄ content of 20 wt.% was achieved, with k_p 28.32% higher than that of pure TiO₂ photocatalyst. Moreover, the experiments on recycled use of TiO₂/NMs photocatalyst demonstrated a good repeatability of the photocatalytic activity.