Synthesis of CeO2-NPs by chemical and biological methods and their photocatalytic, antibacterial and in vitro antioxidant activity

In the present study, biosynthesized CeO 2 -NPs using Solanum nigrum leaf extract were compared with chemically synthesized one. The synthesized CeO 2 -NPs were characterized by UV–Vis, XRD, DLS, ZP, HR-TEM, FT-IR and PL techniques. UV–visible spectrum showed absorption peak in the range of 326–355 nm. DLS studies exposed that the average size of CeO 2 -NPs was around 45 nm and the obtained zeta potential value of − 25.83 mV for CeO 2 -NPs indicated moderate stability of biosynthesized nanoparticles. HR-TEM images revealed the spherical morphology of the biosynthesized CeO 2 -NPs with the size of 20 nm and selected area diffraction pattern revealed the polycrystalline nature of CeO 2 -NPs, which was consistent with the XRD result. FT-IR analysis also confirmed the presence of metal oxide. The synthesized CeO 2 -NPs exhibited potential photocatalytic activity towards the degradation of methylene blue dye upon exposure to sunlight irradiation. The degradation efficiencies of Chem and biosynthesized CeO 2 -NPs towards methylene blue dye were 78.14 and 94.58%, respectively. In addition, antibacterial and antioxidant activity of synthesized CeO 2 -NPs is evaluated. The biosynthesized CeO 2 -NPs possess highest antibacterial activity against Gram-negative Escherichia coli (22 ± 0.3 mm) and Gram-positive Bacillus subtilis (21 ± 0.4 mm) at 100 μl. The biosynthesized CeO 2 -NPs exhibited greater inhibition on DPPH radical IC 50 μg/ml value which was 139 ± 45, while it was 131 ± 21 for hydroxyl radical. The present work demonstrated an eco-friendly preparation of CeO 2 -NPs with good photocatalytic, antibacterial and antioxidant properties.