A Novel Photocatalyst and Antibacterial Agent Based on Cu ₂ O/MgAlCu Layered Double Hydroxides p–n Heterojunction in the Presence of <i>Sapindus Saponaria</i> L. Extract Biosurfactant

Abstract This study explores Cu 2 O nanoparticles supported on Mg‐Al‐Cu layered double hydroxides (MgAlCu‐LDH), synthesized using L‐ascorbic acid as a reducing agent and Sapindus saponaria extract as a biosurfactant to enhance the stability, photocatalytic ability, antibacterial activity and environmental friendliness of LDH/Cu 2 O nanocomposite. The MgAlCu‐LDH was synthesized by incorporating copper (II) ions into an MgAl‐LDH structure before reducing some of the copper (II) ions to Cu 2 O nanoparticles on the surface of MgAlCu‐LDH. The obtained nanocomposites were characterized by FT‐IR, SEM, HR‐TEM‐SAED, DLS, UV‐Vis, XRD, XPS, TGA, PL and BET methods. Additionally, antibacterial tests showed strong efficacy against Escherichia coli, Bacillus cereus, and Pseudomonas stutzeri B27 bacteria, particularly for the nanocomposite prepared at the molar ratio of Mg/Al/Cu of 3/1/0.5. This nanocomposite sample also exhibited excellent photocatalytic performance in degrading Remazol Midnight Black dye with a degradation efficiency of 91.99 ± 0.04% under pH of solution of 5 after 150 min of contact. Moreover, the nanocomposite can degrade the real dye wastewater under xenon irradiation. These results highlight Cu 2 O/MgAlCu‐LDH nanocomposite as an effective, sustainable photocatalyst for dye degradation and antimicrobial applications, contributing to eco‐friendly water treatment solutions.