Biogenic synthesis of Co3O4 nanoparticles from Aloe barbadensis extract: Antioxidant and antimicrobial activities, and photocatalytic degradation of azo dyes

The synthesis of Co3O4 nanoparticles (NPs) through biogenic means offers a cost-effective, environmentally friendly, stable, versatile, and biocompatible approach. In this work, we employed Aloe barbadensis Miller leaf extract for the biosynthesis of Co3O4 NPs, leveraging its rich composition of phenolic groups, polysaccharides, enzymes, minerals, vitamins, and various acids. The characterization of the synthesized NPs was performed using XRD, TEM, EDS, FT-IR, TGA-DSC, Raman, XPS, and particle size analysis techniques. Our investigation focuses on evaluating the antioxidant and antimicrobial properties of Co3O4 NPs. Antioxidant activity was assessed through DPPH, ABTS, FRAP, and FICA assays, demonstrating the NPs' ability to scavenge free radicals, reduce ferric ions, and chelate ferrous ions. Antimicrobial testing revealed the effectiveness of NPs against Proteus mirabilis and Staphylococcus aureus. Furthermore, biogenic Co3O4 NPs were utilized as photocatalysts for the degradation of azo dyes (RhB, MB, and CV). Under sunlight exposure for 105 min, biogenic Co3O4 NPs degraded CV dyes by 97.53%. The study also highlighted the remarkable efficiency of azo dye degradation across five cycles of reuse of biogenic Co3O4 NP reuse.