Development of high-entropy (Mn0.6Cr0.6Co0.6Li0.6Al0.6)O4 ferrimagnetic oxide for efficient photocatalytic degradation of organic dye

A spinel structured and equiatomic-high-entropy oxide (Mn_0.6Cr_0.6Co_0.6Li_0.6Al_0.6)O₄ (MCCLAO) was prepared through sol-gel method followed by calcination at 900 °C in air environment. The MCCLAO displayed a soft-ferrimagnetic nature, despite at room temperature, the individual oxides exhibit either antiferromagnetic or paramagnetic properties, and it does not contain Fe. Magnetic spinel based high entropy oxides without Fe are not reported in the literature. Structural and morphology studies were performed with the help of X-ray diffractometer (XRD) and electron microscopy techniques (TEM). XRD and TEM study results have confirmed the formation of nanosized single-phase MCCLAO. The oxidation states for the elements contained in MCCLAO were also investigated by (XPS) X-ray photoelectron spectroscopy technique. This was an added advantage to recover MCCLAO easily through magnetic separation after four cycles of degradation of methylene blue (MB). The nanosized (~ 18 nm) MCCLAO had relatively higher surface area to enhance its activities. Hence, the MCCLAO demonstrated outstanding photo-Fenton catalytic activity in degrading methylene blue (MB) dye, achieving complete degradation within 90 minutes. Also, effectiveness of the photo-Fenton process in breaking down and mineralizing MB was confirmed through gas chromatography mass spectroscopy (GCMS)analysis.