Sol–gel synthesis of visible-light-driven Ni(1−x)Cu(x)Fe2O4 photocatalysts for degradation of tetracycline

Abstract Magnetically separable, visible-light-driven Ni(1−x)Cu(x)Fe2O4 (Cu–Ni ferrite) photocatalysts have been successfully synthesized via a simple sol−gel precursor method. The prepared samples were characterized by a combination of various physicochemical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectrum (DRS) and photoluminescence (PL). Visible-light-driven photodegradation of tetracycline (TC) was carried out to evaluate the photocatalytic activity of the products. The copper doping can greatly enhance photocatalytic activity in comparison with pure NiFe2O4 for degradation of TC. The significant enhancement of photoactivity can be ascribed to the reduction of the nickel ferrite band gap and lower recombination of photoinduced electron–hole pairs by Cu2+ doping. In addition, the photocatalytic mechanism was analyzed by different active species trapping experiments. The results indicated that the h+ and OH were the main active species for photocatalytic oxidation of TC in the aqueous solution. Moreover, the Cu–Ni ferrite photocatalysts exhibit excellent photostability and recyclability properties which are beneficial for its practical application.