A Novel Mesoporous Al2O3@Graphene Composite as Photocatalyst for Organic Pollutant Removal

In this work, a microwave irradiation approach was employed to synthesize Al2O3 nanoparticles uniformly adhered onto graphene sheets (Al2O3@GR), which were subsequently used as photocatalysts for the degradation of organic dyes methylene blue (MB) and rhodamine B (RhB). The structural, morphological, and optical properties of the Al2O3@GR nanocomposite were comprehensively analyzed using x-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDS), transmission electron microscopy (TEM), and Raman, photoluminescence (PL), and x-ray photoelectron spectroscopy (XPS) techniques. XRD and TEM analyses confirmed the uniform coating of Al2O3 nanoparticles with a face-centered cubic crystal structure on the graphene sheets. Brunauer-Emmett-Teller (BET) analysis revealed the mesoporous nature of the composite, with a high surface area and large pore size. Ultraviolet-visible (UV-Vis) and PL studies indicated a significant reduction in bandgap energy and enhanced electron-hole pair generation. XPS analysis validated the oxidation states of the elements, confirming the successful synthesis of the composite. The influence of catalyst dosage, scavenger activity, and pH on the degradation process was thoroughly investigated. The Al2O3@GR composite demonstrated superior photocatalytic performance, achieving degradation efficiencies of 95% for MB and 84% for RhB, significantly outperforming pristine Al2O3. These findings highlight the potential of Al2O3@GR as an efficient photocatalyst for environmental remediation and the treatment of industrial wastewater.