Plant Assisted Synthesis of Li-doped Mn3O4 Nanoparticles Using Madhuca longifolia Leaf Extract for Enhanced Photocatalytic, Electrochemical and Antimicrobial Applications

Abstract

In this study, lithium (Li) doped Mn3O4 nanoparticles (NPs) were synthesized through a plant-assisted route using Madhuca longifolia (M. longifolia) leaf extract and investigated for their multifunctional properties. The structural, morphological, optical, electrochemical, photocatalytic and antimicrobial characteristics of the synthesized nanoparticles were systematically evaluated. X-ray diffraction analysis confirmed the crystalline nature of Mn3O4 with an average crystallite size of 23.6 nm, Williamson-Hall analysis yielded a crystallite size of 45.26 nm, indicating the presence of lattice strain. FTIR analysis further confirmed the characteristic vibrational features of Mn3O4. UV-Visible spectroscopy revealed an optical band gap of 3.05 eV. Transmission Electron Microscopy (TEM) analysis confirmed nanoscale morphology, while Energy Dispersive X-ray Analysis (EDAX) verified the major elemental composition. Electrochemical measurements exhibited pronounced redox behavior, with an average specific capacitance of 216.43 F/g and a maximum value of 622.5 F/g at 5 mV/s. The biosynthesized NPs exhibited antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. In addition, the nanoparticles achieved degradation efficiencies of 77.6% for methylene blue (MB) and 80.91% degradation of methyl orange (MO) under the investigated conditions. The present work highlights the potential of M.longifolia leaf extract as a sustainable plant source for the preparation of Li-Mn3O4 nanoparticles and demonstrates their multifunctional applicability in electrochemical energy storage, photocatalysis, and antimicrobial applications.