Binary metal (Zn/Ce) co-doped Co3O4 nanoparticles: Characterization and comparative evaluation of photocatalytic, antibacterial and antioxidant potential

Here, tricobalt tetraoxide (Co₃O₄) nanoparticles (NPs) were successfully synthesized with co-dopants Zn and Ce using Citrus limon (C. limon) leaf extract. The products from green reaction mediated synthesis were further investigated for their efficiency for three applications including photocatalytic degradation of congo red (CR) and rhodamine B (RB), antibacterial and antioxidant potential for biomedical applications. Prior to the applicative part, green synthesized Co₃O₄ NPs were characterized for evaluating structural, vibrational, morphological, compositional, and optical parameters using established characterizations like X-ray diffraction, FTIR, SEM/TEM, EDX, and UV–vis spectroscopy. The XRD results showed a reduction in crystallite size from pure Co₃O₄ NPs (11.46 nm) to Zn, Ce, and Zn/Ce co-doped Co₃O₄ (9.73 nm) NPs with extended dislocation density and strain. The change in bond length parameters due to the addition of Zn and Ce was also confirmed by FTIR analysis. The morphological variations with the dopants and confirmation of elemental composition were done using SEM-EDS mapping and TEM results. The UV–vis results inferred the absorption regions of synthesized samples with 1.50 eV band gap energy for pure, 1.45 eV for Zn doped, 1.44 eV for Ce doped, and 1.31 eV for co-doped samples. Based on the results, the co-doped Co₃O₄ NPs exhibited significantly higher photodegradation and antibacterial and antioxidant results.