Preparation of the CaAl₂O₄:Eu²⁺, Nd³⁺/TiO₂ composite by peroxo titanium complex solution and its photodegradation of methylene blue

CaAl₂O₄:Eu²⁺, Nd³⁺ phosphor was synthesized by a solid-state method at 1400 °C. The CaAl₂O₄:Eu²⁺, Nd³⁺ phosphor particles were coated by sol–gel dip coating method with a peroxo treated titanium hydroxide complex solution. The effect of peroxo treatment time and calcination temperatures was investigated in comparison with conventional TiO₂-sol coated nanocomposites. Characterization of the CaAl₂O₄:Eu²⁺, Nd³⁺/TiO₂ nanocomposites was conducted by X-ray diffraction, scanning electron microscopy, UV–Vis absorption spectra, and energy dispersive spectroscopy. The photocatalytic reactivity was evaluated by degradation of methylene blue aqueous solution under ultra-violet and visible light irradiations. CaAl₂O₄:Eu²⁺, Nd³⁺/TiO₂ composite coated with peroxo titanium complex solution for 80 s showed the fastest photocatalytic reactivity under ultra violet and visible light illumination. Peroxo treatment for a long soaking time of 300 s effected etching of the phosphor surface and formation of CaTiO₃ phases. With prolongation of the time of soaking the phosphor in the peroxo titanium complex solution to 300 s, the photocatalytic reactivity of the CaAl₂O₄:Eu²⁺, Nd³⁺/TiO₂ composite decreased. In addition, composites displayed excellent photocatalytic under visible light irradiation, compared with pure TiO_2. The acidity of the peroxo treatment, soaking time, and heat treatment conditions are important parameters for synthesizing photoactive nanocomposites for pollution control application. Graphic abstract: CaAl₂O₄:Eu²⁺, Nd³⁺ was coated with peroxo treated TiO₂-sol under different coating times. The peroxo treatment imparted acidic pH while longer soaking times resulted in etching of the phosphor surface. A wavy micro-ridge microstructure with dispersed clusters of TiO₂ was dominant in the 300 s coated samples. The samples without peroxo treated (CTB) and 80 s coated samples were densely coated with TiO₂ nanoparticles. The CaAl₂O₄:Eu²⁺, Nd³⁺/TiO₂ samples coated in peroxo titania sol exhibited the most superior photocatalytic degradation of methylene blue aqueous solution under ultra-violet and visible light irradiations. [Figure not available: see fulltext.].