Hydrothermal synthesis of Mn3O4 nanoparticles by evaluation of pH effect on particle Size formation and its antibacterial activity

Abstract

In this work, we report a simple, controlled strategy to prepare manganese oxide nanoparticles (Mn3O4 NPs) using one-step, eco-friendly hydrothermal synthesis method. The effect of Mn3O4 NPs size using different levels of pH 8, pH 10 and pH 12 at short processing time and low temperature was investigated. The prepared Mn3O4 NPs structure and surface morphology analyses were characterised by using different techniques such as x-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), and high resolution transmission electron microscopy (HR-TEM). The elemental analysis was confirmed from EDAX spectra. The XRD patterns of Mn3O4 NPs have tetragonal hausmannite structure with a same phase. The surface morphology of Mn3O4 NPs was in unique spherical shape, which was confirmed from both SEM and HR-TEM techniques. The Mn3O4 NPs were prepared at different pH levels, which showed the impact on increase of particle size. After that the antibacterial activity of Mn3O4 NPs against gram-positive and gram-negative bacteria was performed by disk diffusion method. The obtained results of synthesised Mn3O4 NPs have exhibited better antibacterial activity against gram-negative bacteria like Klebsiella pneumoniae (MTCC 532) and Pseudomonas aeruginosa (MTCC 1688) than two remaining microorganisms like Bacillus subtilis (MTCC 10619) and Salmonella ebony (MTCC 3384).