Pristine and Graphene-Quantum-Dots-Decorated Spinel Nickel Aluminate for Water Remediation from Dyes and Toxic Pollutants

Pristine nickel aluminate and the one decorated with graphene quantum dots were prepared via a cost-effective co-precipitation method. Both were fully characterized by thermogravimetry (TGA), differential scanning calorimetry (DSC), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), and UV-Vis techniques. The photocatalytic activity of nickel aluminate under simulated solar light irradiation was demonstrated towards potential pollutants, including a series of dyes (rhodamine B, quinoline yellow, eriochrome black T, methylene blue), toxic phenol and fungicide (thiram). Further profound enhancement of the photocatalytic activity of nickel aluminate was achieved after its decoration with graphene quantum dots. The mechanism of the photocatalytic degradation in the presence of the NiAl2O4/graphene quantum dots (GQDs) composite was investigated; hydroxyl radicals were found to play the leading role. This work offers new insight into the application of the conjunction of the inorganic spinel and the carbon nanostructure (i.e., GQDs), but also provides a simple and highly efficient route for potential water remediation from common pollutants, including dyes and colorless harmful substances.