Novel Magnetic Retrievable Visible-Light-Driven Ternary Fe<sub>3</sub>O<sub>4</sub>@NiFe<sub>2</sub>O<sub>4</sub>/Phosphorus-Doped g-C<sub>3</sub>N<sub>4</sub> Nanocomposite Photocatalyst with Significantly Enhanced Activity through a Double-Z-Scheme System
Priti Mishra, Arjun Behera, Debasmita Kandi, Satyajit Ratha, Kulamani Parida
Abstract
Nickel ferrite (NiFe2O4) and magnetite (Fe3O4) are established earth-abundant materials and get tremendous attention because of magnetic and high photocatalytic activity. First we fabricated novel Fe3O4@20 wt % NiFe2O4/phosphorus-doped g-C3N4 (M@NFOPCN) using a convenient simple coprecipitation method followed by calcination at 400 °C. Then M@NFOPCN composites were prepared by the in situ growth of Fe3O4 nanorods and cubes on the surfaces of a porous agglomerated NFOPCN nanostructure, varying the weight percentage of Fe3O4. A series of characterizations like X-ray diffraction, UV–vis diffuse-reflectance spectroscopy, photoluminescence, Fourier transform infrared, thermogravimetric analysis–differential thermal analysis, vibrating-sample magnetometry, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy techniques confirm that changing weight percentage of M can constructively control the textural characteristics, internal strain, size of the crystals, and other aspects meant for photocatalytic activity. When M was coupled with NFOPCN, magnetic loss was lowered and also an appreciable saturation magnetization (Ms) was obtained. 40 wt % M@NFOPCN showed admirable photostability and was capable of evolving 924 μmol h–1 H2 when irradiated under visible light. The percentage of degradation for ciprofloxacin (CIP) by this ternary nanocomposite was almost 2-fold greater than those of the pure M and NFOPCN photocatalysts. A plausible photocatalytic mechanism for the degradation of CIP antibiotic was established. Hence, this study presents a reusable, low-cost, noble-metal-free, environmentally friendly, fast, and highly efficient 40 wt % M@NFOPCN photocatalyst, achieving 90% degradation of CIP antibiotic under visible light. The double-Z scheme triggers charge separation and migration, enhances visible-light harvesting, and helps in internal electric-field creation, thus headed toward dramatic augmentation of the photocatalytic activity.