High entropy spinel oxide for natural sunlight-driven photocatalytic degradation of methylene blue: a sustainable water remediation process

High entropy materials have garnered substantial attention in the field of materials science due to its tunable properties in various structural and functional applications. This work demonstrates for the first time a facile synthesis of high-entropy spinel oxide (HESO) for natural sunlight-driven photocatalytic dye degradation. The oxide catalyst with a nominal composition (CoCrFeMnNi)3O4 was prepared by a modified sol-gel method followed by a heat treatment at 950 °C. The synthesized powder was characterized for its composition, morphology, and photocatalytic activity. The X-ray diffraction and the X-ray photoelectron spectroscopy analysis confirmed the formation of (CoCrFeMnNi)3O4 with high compositional purity. Methylene Blue dye was chosen for gauging the photocatalytic activity of the prepared material subjected to sunlight irradiation. The catalyst showed a rapid decomposition rate with greater than 95 % degradation efficiency in 100 min. It was found that the prepared high entropy catalyst can degrade the dye under varying reaction conditions, and the spent catalyst can quickly be recovered using an external magnetic field. Also, the most probable reaction mechanism and kinetic model for photocatalysis have been investigated.