Green synthesis of orthorhombic Mn2O3 nanoparticles; influence of the oxygen vacancies on antimicrobial activity and cationic dye degradation

Abstract

An environmentally friendly bottom-up method for oxidizing and reducing heterocyclic chemicals from biological sources and producing metal oxides is proposed. Due to the high amount of phenolic and sulphated flavonoids (OH and C–O–S groups) in the Cissus quadrangularis leaf extract, reducing and capping agents were able to make an orthorhombic nanostructure of Mn₂O₃ nanoparticles (NPs), which decreased the acidity. The enhanced parameter is modified to improve the oxygen vacancies proportional to the Mn³⁺ octahedral faces and oxygen atoms in the tetrahedral interstitial regions, as well as the surface charge density of the leaf extract, in order to generate the orthorhombic structure. In addition to the identification of reduced Mn species (Mn²⁺) via diffraction (XRD) and X-ray photon electron microscopy (XPS), the obtained materials were characterized via UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and high-resolution transmission electron microscopy (HR-TEM). The antimicrobial effect of the orthorhombic Mn₂O₃ NPs as prepared was studied towards bacteria (Proteus mirabilis, Aeromonas hydrophila) and fungi (Aspergillus flavus) over their individual elements, including Gram-negative bacteria and fungi for 21, 17, and 17 mm ZOI, respectively. The significant operational parameters, including the loaded catalyst amounts, pH, methylene blue (MB) concentration, and reusability produced a better performance MB degradation proportion of 81%. Thus, the produced Mn₂O₃ NPs can be employed as promising catalysts for both biomedical applications and industrial dye degradation.