Porous Layered Double Hydroxide/TiO₂ Photocatalysts for the Photocatalytic Degradation of Orange II

• Main Authors: Rodrigue Djeda, Gilles Mailhot, Vanessa Prevot
• Format: Article
• Language: English
• Published: MDPI AG 2020-06-01
• Series: ChemEngineering
• Subjects: photodegradation; titanium dioxide; LDH; Orange II; nanocomposites; coprecipitation
• Online Access: https://www.mdpi.com/2305-7084/4/2/39

Layered Double Hydroxide (LDH)/TiO₂ nanocomposites with photocatalytic properties were synthesized by both impregnation and the direct coprecipitation of LDH matrices using a colloidal suspension of TiO₂ nanoparticles. While the two methods led to an efficient TiO₂ nanoparticle immobilization, the direct coprecipitation allowed us to tune the amount of immobilized TiO₂ within the materials. The LDH/TiO₂ nanocomposites obtained were deeply characterized by chemical analysis (ICP-AES), Powder X-ray diffraction (XRD), Fourier Transformed Infra-Red (FTIR), Thermogravimetric analysis (TGA), and High-Resolution Transmission Electron Microscopy (HRTEM). Clearly, the immobilization of TiO₂ by direct coprecipitation promoted a modification of the textural properties and a net increase in the surface area. The crystallized TiO₂ nanoparticles can be distinctly visualized by HRTEM at the surface of the layered material. Several parameters, such as the nature of the chemical composition of LDH (ZnAl and MgAl), the method of immobilization and the amount of TiO₂, were shown to play a crucial role in the physicochemical and photocatalytic properties of the nanocomposites. The photocatalytic efficiency of the different LDH/TiO₂ nanocomposites was investigated using the photodegradation of a model pollutant, the Orange II (OII), and was compared to a pure TiO₂ colloidal solution. The degradation tests revealed that the nanocomposite obtained from MgAl LDH at a low MgAl LDH/TiO₂ ratio was the most efficient for the photodegradation of OII leading to complete mineralization in 48 h.