Novel CuCr₂O₄ embedded CuO nanocomposites for efficient photodegradation of organic dyes

Graphical abstract: - Highlights: • Novel CuO–CuCr₂O₄ nanocomposites synthesized by reflux condensation method. • Methyl orange and methylene blue dye degradation studied under UV light irradiation. • Nanocomposites characterized by XRD, FESEM, TEM, EDX, UV–vis DRS and PL. • CuCr₂O₄ loading effectively enhanced the catalytic activity of CuO. - Abstract: Novel photocatalyst based on CuO–CuCr₂O₄ nanocomposites was synthesized for different Cr³⁺ concentration by reflux condensation method, and their photocatalytic activity was evaluated by monitoring the photodegradation of methyl orange (MO) and methylene blue dyes (MB) under UV light irradiation. Phase evolution by X-ray diffraction showed monoclinic CuO and tetragonal CuCr₂O₄ as the components of the prepared nanocomposites. Morphological analysis by scanning electron microscope and transmission electron microscope revealed that the incorporation of Cr³⁺ in CuO lattice alters the morphology of CuO from microsphere to cluster shape. Photoluminescence spectra of CuO–CuCr₂O₄ nanocomposites exhibited reduced PL emissions compared to pure CuO, indicating the low recombination rate of photogenerated electrons and holes. As expected, the CuCr₂O₄ loaded CuO showed enhanced photocatalytic activity for MO and MB dyes, and the kinetic studies suggest that the degradation follows pseudo-first-order kinetics. The enhanced photocatalytic activity of CuO–CuCr₂O₄ nanocomposites can be attributed to the presence of CuCr₂O₄ as an electron acceptor, which improves the effective charge separation in CuO.