Magnetic Photocatalyst Nanocomposite Based on MnFe₂O₄@ZnO for AZO Dye Degradation

This work focuses on fabricating a photocatalyst nanocomposite based on MnFe₂O₄@ZnO for degrading Red Amaranth azo dye. Manganese ferrite (MnFe₂O₄) magnetic nanoparticles were synthesized via a hydrothermal method, while a ZnO thin film, acting as the photoactive layer, was deposited on the magnetic cores using the atomic layer deposition (ALD) technique. X-ray diffraction (XRD) confirmed the spinel ferrite structure of MnFe₂O₄ and the hexagonal wurtzite phase of ZnO. The crystallite size, determined from the (311) peak, was 36.5 nm; this value was consistent with the average size of 33.2 nm measured by transmission electron microscopy (TEM). Magnetic characterization via vibrating sample magnetometry (VSM) at room temperature revealed a superparamagnetic behavior, determined by a very small hysteresis loop. The ZnO coating, achieved with 200 ALD cycles, resulted in a degradation efficiency η_eff of approximately 60% for the Red Amaranth dye. Finite-difference time-domain (FDTD) simulations provided theoretical insights into the electromagnetic interactions driving the photodegradation process, supporting the UV-vis absorbance data of the AZO dye. This nanocomposite can be considered as a soft magnetic material that offers promising applications in nanotechnology for environmentally friendly wastewater treatment and remediation.