GO-enhanced photocatalytic breakdown of emamectin benzoate by an MgO-CuO nanocomposite under visible light...

The persistent accumulation of recalcitrant pesticide residues poses a significant environmental challenge. Emamectin benzoate, a highly toxic and recalcitrant pesticide extensively used in modern agriculture, has emerged as a critical environmental contaminant due to its persistence, bioaccumulation potential and resistance to conventional degradation pathways. Conventional photocatalysts are limited by their inefficient interfacial charge transfer and rapid charge recombination. To address these limitations, an MgO-CuO/GO ternary heterostructure is rationally engineered, in which GO acts as a conductive carbon-based mediator to facilitate charge migration. The resulting Z-scheme pathway enables efficient charge separation while preserving strong redox potentials for enhanced reactive oxygen species generation. XRD reveals the improved crystallinity of the nanosheets upon the incorporation of GO. SEM indicates the uniform distribution of the MgO-CuO nanostructures over the GO sheets, indicating effective integration and reduced agglomeration, while TEM images confirm the intimate interfacial contact between MgO-CuO and GO, forming a well-dispersed heterostructure with enhanced structural coupling. 4.0 wt% MgO-CuO/GO nanosheets exhibit a significantly reduced band gap (1.72 eV) owing to the synergistic coupling of metal oxides with GO, thereby enhancing visible-light absorption. FTIR spectroscopy indicates distinct shifts in the C-O and C[double bond, length as m-dash]O vibrations, suggesting strong interfacial interaction and chemical coordination between the GO and metal oxides. The 4.0 wt% MgO-CuO/GO nanocomposite shows the highest degradation activity of 75% with a rate constant of 0.27 h^-1 for emamectin benzoate degradation. The combined effect of these components results in superior photocatalytic degradation of emamectin benzoate, affording highly efficient materials for environmental remediation.