Today, photocatalysis is the most cost-effective and ecologically beneficial technique for tackling the growing problem of water pollution caused by rapid industrialization. The fabrication of a new photocatalyst with quicker charge transport, superior charge separation, narrow bandgap energy, reduced electron-hole pair recombination rate, and good light-harvesting characteristics is a major challenge for materials researchers. So herein, we used the microemulsion method to synthesize Ce-doped (rare-earth metal) cobalt/nickel mixed metal ferrite (C-X@CNMF, X = 0%, 3%, 6%, 9%, 12%, and 15%). Application studies revealed that C-9@CNMF material mineralizes the Congo red (CR) dye to a greater extent than that of C-0@CNMF under visible light irradiation. At the completion of the photodegradation reaction, nanostructured C-9@CNMF material completely mineralized CR-dye, whereas only 45.11%, 49.6%, and 73.3% of the CR-dye was removed by C-0@CNMF, C-3@CNMF, and C-15@CNMF nanoparticles. The kinetic tests showed that C-9@CNMF material mineralized the CR-dye at a rate (k = 0.0336 min−1) that is approximately 6.72 times quicker than that of the C-0@CNMF sample (0.0050 min−1). Aside from that, the C-9@CNMF material showed exceptional recyclability and photo-corrosion resistance, losing just 7.5% of its photocatalytic activity after five cycles of CR-dye degradation. The dominating photocatalytic performance of the C-9@CNMF sample is mainly attributed to its nanoarchitecture (44.8 nm), larger specific surface area (57.6 m2/g), tunable bandgap (2.13 eV), and effective charge separation characteristics.
