Sunlight‐Driven Dye Degradation Studies of g‐C ₃ N ₄ ‐Based Quaternary Nanocomposite

ABSTRACT

Graphitic carbon nitride (g‐C ₃ N ₄ ) has attracted enormous attention recently owing to its excellent photocatalytic activities. Its photocatalytic activities can be further enhanced by making composites with other materials; however, developing simple and efficient methods for fabricating such multiphase composites remains a considerable challenge. In this work, we report on facile synthesis and photocatalytic studies of g‐C ₃ N ₄ /Ag/α‐Fe ₂ O ₃ /CoFe ₂ O ₄ quaternary nanocomposites. The g‐C ₃ N ₄ was synthesized using a thermal condensation of urea. Silver was incorporated into the g‐C ₃ N ₄ by in situ reduction of Ag ions in the g‐C ₃ N ₄ matrix. Finally, sonification was used to incorporate CoFe ₂ O ₄ NPs, prepared by the co‐precipitation method, into the composite. The composite was analyzed by x‐ray diffraction (XRD), transmission electron microscope (TEM), and Fourier‐transform infrared spectroscopy (FTIR). To study the comparative photocatalytic potential of the samples, we studied the degradation of methylene blue (MB), which is a toxic dye, in the presence of sunlight. Radical scavenger experiments revealed that superoxide radicals (•O ₂ ⁻ ) and hydroxyl radicals (•OH) play dominant roles in the photocatalytic degradation process. Furthermore, due to the presence of magnetic CoFe ₂ O ₄ , the photocatalyst could be recovered from the reaction medium using an external magnet and reused for multiple cycles. The degradation efficiency decreased slightly from 98% in the first cycle to 93%, 85%, and 78% after the second, third, and fourth cycles, respectively, demonstrating good stability and reusability. The superior catalytic performance of the composite is due to the enhanced sunlight absorbance combined with the synergetic effects within the composite, which reduces electron–hole recombination and increases the reaction rate.