Green synthesis of MnO₂ nanoparticles from Psidium guajava leaf extract: Morphological characterization,...

In this work, a simple, efficient and eco-friendly green synthesis of manganese dioxide nanoparticles (MnO₂NPs) by Psidium guajava leaf extract was described. Fourier-Transform infrared spectra results revealed that involvement of the plant extract functional groups in the formation of MnO₂NPs. The UV-vis absorption spectra of the synthesized MnO₂NPs exhibited absorption peaks at 374 nm, which were attributed to the band gap of the MnO₂NPs. Crystal phase identification of the MnO₂NPs were characterized by X-ray diffraction analysis and the formation of crystalline MnO₂NPs have been confirmed. Furthermore, scanning electron microscopy analysis showed that the synthesized MnO₂NPs have a spherical in shape. Interestingly, the prepared green synthesized MnO₂NPs showed catalytic degradation activity for malachite green dye. Malachite green's photocatalytic degradation was detected spectrophotometrically in the wavelength range of 250-900 nm, and it was discovered to have a photodegradation efficiency of 75.5 % within 90 min when exposed to solar radiation. Green synthesized MnO₂NPs are responsible for this higher activity. An interaction between synthesized NPs and biomolecules, including CT-DNA and BSA was also evaluated. The spectrophotometric and Fluoro spectroscopic analyses indicate a gradual reduction in peak intensities and shifts in wavelengths, indicating binding and affinity between the NPs and the biomolecules.