Annona muricata leaf extract mediated synthesis of pure and Co doped TiO2 nanoparticles: Evaluation of catalytic reduction, antimicrobial and antioxidant activities

One of the main concerns in the world today is protecting the environment from air, water and microbial pollution. Therefore, it is crucial to develop a safe and effective antimicrobial, antioxidant and photocatalytic agent through an eco-friendly green method using Annona muricata leaf extract to produce pure and Cobalt (Co) doped TiO2 nanoparticles. The materials are characterized using XRD, FTIR, XPS, HRTEM-SAED, SEM-EDX and UV-Visible spectroscopy to explore structural, morphological and optical features. The crystallinity, phase purity and anatase structure of each sample were established by XRD analysis. FTIR spectra verified the existence of specific vibrational modes, while XPS measurements confirmed the successful incorporation of Co2+ ions into the TiO2 host lattice. HRTEM images reveal isolated spherical morphology with clear lattice fringes, while the SEM image sponge like nanoparticle. The EDAX spectra contain Ti, Co and O elements, indicating the purity of sample. The optical bandgap, determined through UV Visible spectra, indicates a reduction in energy bandgap with an increase in dopant concentration. However, Ti0.93Co0.07O2 nanoparticles exhibit the highest antibacterial activity against both Gram negative and Gram positive bacterial strains. Moreover, antifungal studies show that C.albicans exhibit highest zone of inhibition compared to A.niger. Furthermore, TiO2 and Ti0.93Co0.07O2 nanoparticles exhibit significant antioxidant activity with IC50 values of 471.64 mu g/mL and 237.73 mu g/mL respectively, in DPPH radical scavenging. Additionally, the photocatalytic activity was analysed for methylene blue and congo red dye degradation. Ti0.93Co0.07O2 nanoparticles demonstrate the best photocatalytic performance, with efficiencies of 87% and 90% towards both pollutants under direct sunlight irradiation. Thus, current investigation demonstrates the effective preparation of nanoparticles using A.muricata leaves, providing a sustainable solution for enhancing catalytic degradation, food safety, antimicrobial properties and anticancer drug development.