This work uses co-doped Mn2+ and Dy3+ ions to enhance photocatalytic degradation and magnetic properties of cobalt nanomaterials. A simple sol–gel auto-combustion method was used to fabricate spinel nano-ferrite \({\text{Co}}_{1-\text{y}}{\text{Mn}}_{\text{y}}{\text{Dy}}_{\text{x}}{\text{Fe}}_{2-\text{x}}{\text{O}}_{4}\) , conventionally composed of nanoparticles of x,y = 0.00-DYMN-0, 0.02-DYMN-1, 0.04-DYMN-2, 0.06-DYMN-3, 0.08-DYMN-4, and 0.1-DYMN-5. The X-ray diffraction (XRD) investigation confirmed the Rietveld refinement-validated pure spinel phase for the DYMN-0 to DYMN-5 samples, with a lattice parameter ranging from 8.3941 to 8.4079 Å (aexp). The surface morphology FESEM + HRTEM investigation assessed the spherical and cubic shape of the ferrite nanoparticle. Using ultraviolet–visible (UV–Vis) spectroscopy, the optical characteristics and energy gaps were evaluated. The direct energy gap was found to fluctuate between 1.50 and 2.20 eV. The two ferrite characteristic bands, υ1 (~ 398–413 cm−1) and υ2 (~ 578–584 cm−1), as well as the Raman modes (A1g, T2g, and Eg), which generate fcc nano-ferrites. The BET surface area analysis demonstrated that for DYMN-0 to DYMN-5, the range was from 18.2 to 24.7 m2/g. The oxidation quantities of the elemental components were further validated by X-ray photoelectron spectroscopy (XPS), confirming the successful incorporation of Mn2+-Dy3+. After co-doping with Mn2+ and Dy3+ ions, the magnetic properties of cobalt ferrite demonstrated a notable improvement. The maximum possible coercivity is 2550 Oe at DYMN-5, and the maximum saturation magnetisation (Ms) is 70.89 emu/g at DYNM-0. This work has significantly enhanced the structural, optical, magnetic, and photocatalytic properties of Mn2+-Dy3+ co-doped cobalt-spinel ferrite nanoparticles, thereby expanding the range of potential applications. The maximum percentage of MB removal for DYMN-5 after 200 min in the sun was 81.01%; the rate of MB decrease was 14.85% separately. Adding Dy-Mn cations leads to a substantial increase in the substance's potential and significantly reduces electron–hole pair recombination.
