Color center defects on modulating magnetic, optical, and catalytic behavior of zinc ferrites

The impact of color center defects on the optical, magnetic, and catalytic properties of lemon peel extract as reducing agent and synthesized pure and doped zinc ferrite nanoparticles via co-precipitation method. The structural characteristics from X-ray diffraction report single phase cubic spinel structure of pure and doped zinc ferrite nanoparticles. The diffuse reflectance spectroscopy reveals a bandgap reduction from 4.79 to 3.34 eV due to the formation of color centers. Additionally, the decrease in the intensity of the photoluminescence spectra upon doping supports the presence of color centers. Doping with magnesium (alkaline earth metal) and aluminium (post transition metal) induced F and F⁺ center defects, while the co-doping generates M center defects, influencing photocatalytic performance. The MB dye degradation efficiencies for Mg-doped, Al-doped, and co-doped ZnFe₂O₄ were 80 %, 83 %, and 75 %, respectively, within 120 min under sunlight. Furthermore, Al-doped ZnFe₂O₄ demonstrated high catalytic stability, retaining 81.4 % degradation efficiency even after seven cycles. The magnetic properties of doped ferrites vary based on the presence of these color centers. This study highlights the synergistic effect of metal doping on bandgap tuning, photocatalytic efficiency, and long-term catalytic stability, offering insights into defect engineering for enhanced environmental remediation.