Visible Light-Driven Photocatalytic Activity of Magnetic Recoverable Ternary ZnFe2O4/rGO/g-C3N4 Nanocomposites

Abstract

ZnFe₂O₄/rGO/g-C₃N₄ ternary nanocomposite photocatalysts with different ZnFe₂O₄/g-C₃N₄ weight ratio (0.5, 0.75, 1) were prepared by a stepwise solvothermal method using ethylene glycol as the solvent. Physicochemical methods such as X-ray diffraction, UV-Vis diffuse reflectance spectroscopy and photoluminescence spectroscopy were applied in order to characterize the composites. The formation of a meso-/macroporous structure with specific surface area between 67 and 77 m² g^‒1 was confirmed by N₂ adsorption/desorption. The bandgap of the composites was found to be lower (2.30 eV) than that of g-C₃N₄ (2.7 eV). In contrast to pure g-C₃N₄, the composites showed no fluorescence, i.e. no recombination of e^‒/h⁺ took place. All samples, including pure g-C₃N₄ and ZnFe₂O₄, were tested for adsorption and photocatalytic degradation of aqueous malachite green model solutions (10^‒5 M) under visible light irradiation (λ >400 nm). The results show that the prepared nanocomposites have higher absorption and photocatalytic activity than the pristine g-C₃N₄ and ZnFe₂O₄ and can be successfully used for water purification from organic azo-dyes.