Engineering ZnO─MgO Nanocomposites for Highly Efficient Sunlight‐Driven Photocatalytic Degradation and Antibacterial Applications

ABSTRACT In this study, ZnO (Z1C6), MgO (M1C6), and ZnO─MgO nanocomposites were synthesized using facile co‐precipitation method. The ZnO─MgO nanocomposites (NCs) were synthesized with varying compositions [MZ1C6 (ZnO─MgO 1:1), MZ2C6 (ZnO─MgO 2:1), and MZ3C6 (ZnO─MgO 3:1)], using a co‐precipitation method. In this work, MgO was incorporated as a band‐structure modulator and defect‐engineering agent to promote interfacial charge separation and endorsing the photocatalytic activity under solar light. The synthesized products were characterized by x‐ray diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM), energy‐dispersive x‐ray spectroscopy (EDAX), field emission scanning electron microscopy (FESEM), and UV–visible spectrophotometric analysis. The optimized ZnO─MgO (3:1) nanocomposites at pH 9 of the dye solution with 50 mg catalyst loading show almost 100% of photocatalytic degradation in 30 min for methylene blue (MB) under sunlight, with a rate constant of 0.148 min −1, confirming rapid degradation dynamics. Advanced mechanistic investigation demonstrated that MgO acts as an electron‐trapping domain while ZnO serves as a hole‐rich photocatalytic center. The nanocomposites exhibited strong recyclability and better antibacterial activity towards both S. aureus and E. coli . Nanocomposite MZ1C6 shows a zone of inhibition of 16 mm for S. aureus . This study demonstrates the potential of ZnO─MgO nanocomposites as effective agents for environmental and antimicrobial applications.