Bi-component cobalt metatitanate and cobalt oxide nano-composite for high efficient photocatalytic degradation of triazo Direct Blue 71: synthesis, characterization and surface properties

A simple and cost effective solvothermal method for the production of bi-component cobalt metatitanate and cobalt oxide nano-composite by cobalt(II) chloride hexahydrate and titanium tetraisopropoxide (TTIP) as starting materials is reported. The prepared nano-composites were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and N₂ adsorption analyzer (Brauner–Emmett–Teller) (BET specific surface area). XRD results showed cobalt metatitanate (CoTiO₃) (70%) a = b = 5.0683 Å, c = 1.922 Å and cobalt oxide (Co₃O₄) (30%) a = b = c = 8.1178 Å as the phases present in nano-composite. FE-SEM and BET results showed that the powder consists of separate particles with 48 nm mean particle size and 8.8 m²/g specific surface areas. FT-IR measurement confirmed the presence of cobalt metatitanate and cobalt oxide in the sample. DRS results showed an optical band gap value of 1.31 eV for nano composite. The photocatalytic activity of nano-composite coated on glass was studied using triazo Direct Blue 71 textile dye in water and the results indicated that degradation efficiency reached 82% with the corresponding 78% TOC removal.