Sol-gel synthesis of Al2O3@ZrO2 nanocomposite as a photocatalyst for degradation of reactive blue 222 dye under visible light irradiation

Zirconia (ZrO2), as an inorganic coating material, is an important n-type semiconductor material that with a great numbers of catalysis in oxidation and reduction can be operated. ZrO2 has attractive properties, showing mild acid catalytic behavior and good mechanical, chemical, and thermal stabilities. In addition, the hydroxyl groups onto the surface of ZrO2 are able to react with different reagents and materials. Therefore, the addition of metal oxide nanoparticles into a layer of ZrO2, providing a core-shell structure (i.e. M (metal oxide)@ZrO2) that may have properties different from each of the components considered separately [1,2]. Al2O3–ZrO2 composite ceramics is a promising material since it possesses the crack resistance and hardness higher than pure aluminum oxide and zirconium oxide, respectively. The combination of mechanical properties and a proper biocompatibility makes the use of the Al2O3–ZrO2 composite ceramics rather promising in dentistry and orthopedic surgery (tooth and joint implants). The Al2O3–ZrO2 composite ceramics can be produced via mixing the aluminum and zirconium oxide powders. However, the nanoscale composite powders are more preferable to apply for the production of composite ceramics. Aluminum and zirconium oxides are not mutually-soluble, however, in the nanoscale state they form mixed oxides [3,4]. In the present work, Al2O3@ZrO2 nanocomposite was prepared using the new sol-gel method. The structure and morphology of samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and energy dispersive analysis of X-ray (EDAX) and UV-vis spectroscopy (UV-vis). Obtained results of XRD data confirmed the formation of Al2O3@ZrO2 nanocomposite. The photocatalytic activity of the nanocomposite was evaluated by studying the degradation of reactive blue 222 as a model dye under visible light irradiation. Obtained results showed that some parameters such as amount of catalyst, irradiation time and initial dye concentration effect on the degradation efficiency of reactive blue 222 dye. The experimental results indicated that the photocatalytic property of the Al2O3@ZrO2 nanocomposite was excellent.