Enhanced visible light-active CeO2/CuO/Ag2CrO4 ternary heterostructures based on CeO2/CuO nanofiber heterojunctions for the simultaneous degradation of a binary mixture of dyes

Abstract

In the present work, a novel CeO₂/CuO/Ag₂CrO₄ ternary nanocomposite based on CeO₂/CuO fibers by loading Ag₂CrO₄ nanoparticles has been prepared using electrospinning, calcination and chemical precipitation methods. The samples were characterized by field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) method and Fourier-transform infrared spectroscopy (FT-IR). The as-obtained CeO₂/CuO/Ag₂CrO₄ composite exhibited excellent photocatalytic performance in the photo-degradation of a mixture of Rose bengal (RB) and methylene blue (MB) in an aqueous solution under visible light (LED) irradiation. DRS analysis illustrated that the CeO₂/CuO/Ag₂CrO₄ composite exhibited enhanced absorption in the visible region, which was attributed to the CeO₂/CuO nanofibers. The as-synthesized photocatalyst demonstrated higher photocatalytic activities compared to the single CeO₂/CuO nanofibers and Ag₂CrO₄ nanoparticles. Furthermore, the ternary composite exhibited the highest RB and MB photo-degradation rates of about 0.0299 and 0.0235 min⁻¹, respectively, at 300 rpm under visible light irradiation. The effect of four effective variables, namely, the initial concentrations of RB and MB, photocatalyst dosage, and irradiation time was studied and optimized using the central composite design. The kinetic studies confirmed the pseudo first order reaction based on the Langmuir–Hinshelwood model, while its rate constant (k_obs) and L–H rate constant (k_r) were 0.097 min⁻¹ and 5.773 mg L⁻¹ min⁻¹ for RB and 0.0669 min⁻¹ and 2.017 mg L⁻¹ for MB, respectively.