Sol–Gel Derived CoAl2O4 Sheets: Synthesis, Characterization, and Photocatalytic Efficiency for Methylene Blue Degradation under Visible Light

Abstract

The synthesis, characterization, and efficient photocatalytic degradation of toxic dyes represent a viable, efficient, and environmentally friendly approach. CoAl₂O₄ spinel was prepared using the sol-gel method and propionic acid as a chelating agent. XRD, FT-IR, DRS, SEM-EDX, and XPS have been employed to explore the structure, chemical bonds, morphology, composition, and optical properties, as well as the surface composition of the material. The XRD patterns revealed the presence of a pure-phase spinel structure with a crystallite size of 35 nm. The SEM analysis exhibited a sheet structure with a lower porosity. The presence of Co, Al, and O was detected by EDX analysis. The band gap of 2.1 eV was calculated from the diffuse reflectance data, and the XPS spectra evidenced the presence of Co (II), Al (III), and O. The photocatalytic activity of CoAl₂O₄ was successfully assisted through the degradation of Methylene blue, an organic pollutant, under visible light irradiation. The effect of pH and electron acceptors was also investigated. The results showed a rate degradation of 15.73% within 90 min at pH ∼ 7, and a substantial degradation of (∼ 100%) was recorded at pH ∼ 3 after 90 min in the presence of the electron acceptors K₂S₂O₈.