Reduced Graphene Oxide Intercalated MgAl-Layered Double Hydroxide for Photocatalytic Degradation of Various Organic Dyes under Ultraviolet and Visible Light Illumination

This study reports the fabrication of a novel series of photocatalysts based on reduced graphene oxide (rGO) intercalated into magnesium aluminum layered double hydroxides (MgAl-LDH), denoted as LDH/rGO(0.25), LDH/rGO(0.5), and LDH/rGO(0.75), where the numeric values represent the mass ratio of LDH to rGO. These nanocomposites were designed to address the escalating issue of organic dye pollution in wastewater. The incorporation of rGO into the LDH matrix significantly improved the electrical conductivity, surface area, and light-harvesting capacity of the hybrid material. Importantly, rGO intercalation led to a notable narrowing of the optical band gap of pristine MgAl-LDH (initially 3.5 eV) to values ranging from 2.4 to 2.9 eV, depending on the rGO content. This reduction enhanced the absorption of visible light and promoted more efficient charge carrier separation and migration. The structural, morphological, and optical properties of the synthesized composites were systematically investigated using FTIR, TEM, and UV–Vis's spectroscopy. The photocatalytic performance was evaluated under both ultraviolet (UV) and visible light irradiation, focusing exclusively on the degradation of the Malachite Green (MG) dye as a representative organic pollutant. Among the composites, LDH/rGO(0.25) exhibited the highest degradation efficiency, achieving up to 93% removal of MG within 50 minutes under optimal conditions (pH=10, dye concentration of 10 ppm, and appropriate catalyst dosage). The improvement of photocatalytic activity is assigned to the synergistic interaction between the LDH layers and rGO nanosheets, as well as the optimized band structure induced by varying rGO content. These findings demonstrate the promising potential of LDH/rGO nanohybrids particularly LDH/rGO (0.25) and LDH/rGO (0.5) as efficient, visible-light-responsive photocatalysts for sustainable wastewater treatment applications.