Biosynthesis of TiO<sub>2</sub>/CuO and Its Application for the Photocatalytic Removal of the Methylene Blue Dye
Getye Behailu Yitagesu, Dereje Tsegaye Leku, Abebaw Matebu Seyume, Getachew Adam Workneh
Abstract
High Resolution Image Download MS PowerPoint Slide In this study, we successfully synthesized a TiO 2 /CuO nanocomposite using the aqueous extract of Impatiens tinctoria A.rich . leaf extract as a capping, reducing, and stabilizing agent for the first time in an environmentally friendly, low-cost, straightforward, and sustainable technique. Numerous characterization techniques such as ultraviolet–visible diffuse reflectance spectroscopy (UV–vis-DRS), photoluminescence (PL), Raman spectroscopy, Fourier-transform infrared (FTIR), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and high resolution TEM (HRTEM) were used to characterize the obtained TiO 2 /CuO nanocomposite. XRD verified that the TiO 2 /CuO nanocomposite has an average crystallite size of about 21 nm. The TEM result revealed an average particle size of 29 nm for the biosynthesized TiO 2 /CuO NC. The HRTEM analysis showed the presence of polycrystalline structures with the predominant lattice fringes 0.352 and 0.19 which were attributed to anatase phase TiO 2 in the crystal plane of (101) and (200), respectively. The lattice fringes for monoclinic CuO were observed with values of 0.213 and 0.252 for the lattice planes of (111) and (111̅), respectively. The photoluminescence spectroscopic analysis revealed that the TiO 2 /CuO NC showed the lowest intensity compared to the pristine TiO 2 and CuO indicating the reduction of exciton recombination in the case of the TiO 2 /CuO NC. The BET analysis showcased the formation of mesoporous materials with a surface area of 87.5 m 2 /g. The photocatalytic degradation performance of the biosynthesized TiO 2, CuO, and TiO 2 /CuO nanomaterials against the potentially harmful MB dye was tested using the light source of a 150 tungsten-halogen lamp with a wavelength range of 360–2800 nm. The factors affecting photodegradation efficiencies like catalyst dose (20 mg), dye concentration(15 ppm), pH (9), and reaction time (90 min) were optimized for the degradation of the MB dye. The TiO 2 /CuO catalyst showed the highest degradation efficiency of 99% under the optimized conditions. The degradation rate of the MB dye in the presence of the TiO 2 /CuO NC was evaluated and found to be fitted to the pseudo-first-order kinetics with a rate constant of 0.03 min –1 . The reusability test of the TiO 2 /CuO catalyst showed its good stability.