Green Synthesis of Carbon Quantum Dots Doped on Nickel Oxide Nanoparticles as Recyclable Visible Light Photocatalysts for Enhanced Degradation of Malachite Green

Abstract

In the present study, carbon quantum dots/nickel oxide composites were successfully synthesized by a simple approach. Carbon quantum dots (CQDs) were prepared via a hydrothermal method from Nigella sativa seeds. Then, CQDs were attached to nickel oxide nanoparticles (NiO) as a new class of photocatalytic materials, which can easily be recycled after photodegradation by applying a magnetic field. Nanocomposites were characterized by X‐ray diffraction (XRD), Fourier‐ transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), UV‐Visible and fluorescence spectroscopy. The photocatalytic activity of the composites was assessed using malachite green (MG) as the target pollutant under visible light irradiation. Our results presented that the powder form of the CQDs/NiO composites exhibited outstanding photocatalytic activity for three cycles and could be well restored through the applied magnetic field after photodegradation. About 98 % degradation of MG dye in the solution was confirmed after 60 min of visible light exposure.