Synthesis and characterization of CuO–Mn₃O₄: application to chromium (VI) photocatalytic reduction

CuO–Mn₃O₄ nanocomposite and its pristine material were synthesized via precipitation method and method and characterized by XRD, SEM with EDX, TEM, UV–DRS, PL, and XPS. XRD, TEM, and SEM analysis prove that the merging of CuO in Mn₃O₄ changes its matrix from orthorhombic to tetragonal structure. The presence of Cu, Mn, and O elements in each sample is confirmed by EDX analysis, while XPS reveals their oxidation states. 30 mg CuO–Mn₃O₄ dosage exhibit the highest efficiency (90.37%) in photocatalytic reduction of aqueous Cr(VI) under halogen lamps (250W) irradiation. Finally, Cr(VI) photocatalysis showed that CuO–Mn₃O₄ reduction should be carried out in acidic medium (pH  5). The CuO–Mn₃O₄ composite exhibits higher photocurrent (1.09 μA cm⁻²) compared with pristine CuO (0.21 μA cm⁻²) and Mn₃O₄ (0.49 μA cm⁻²).