Structural, optical, magnetic, and enhanced antibacterial properties of hydrothermally synthesized Sm-incorporating α-MoO3 2D-layered nanoplates

Abstract

In this study, we have synthesized pristine and [0.5,1.5, and 2.5] M% samarium (Sm)-incorporating α-MoO₃ 2D-layered nanoplates utilizing a facile hydrothermal process, and investigated the physical properties along with antibacterial effectiveness. X-ray diffraction (XRD) patterns confirmed the single-phase, stable orthorhombic polycrystalline structure of the as-prepared samples. The crystallite size, lattice strain, and dislocation density were measured using both Debye–Scherrer (D–S) and Williamson-Hall (W-H) techniques. Both pristine and Sm-incorporating α-MoO₃ samples showed two-dimensional (2D) layered nanoplate-type surface morphology, revealed by field emission scanning electron microscopy (FE-SEM) images. Energy dispersive X-ray spectroscopy (EDS) confirmed the presence of Sm contents in the α-MoO₃ matrix. After Sm incorporation in α-MoO₃, the different functional groups as well as vibrational groups were observed by Fourier-transform infrared (FTIR) spectroscopy and Raman spectroscopy analyses, respectively. The optical band gaps were measured from UV-vis diffuse reflectance spectroscopy (DRS) by employing the Kubelka–Munk formula and interestingly it is found that the bandgap energy (E_g) gradually decreased from 2.96 to 2.83 eV with the increment of Sm content. When compared to pristine α-MoO₃, the Sm-incorporating samples experienced a steady improvement in room temperature ferromagnetic (RTFM) behavior as Sm content increased, as measured by hysteresis loops. The antibacterial activities of both samples were assessed against Gram-positive: Staphylococcus aureus (S. aureus), and Gram-negative: Escherichia coli (E. coli) and Salmonella enteritidis (S. enteritidis) bacteria by the agar well diffusion method and enhanced antibacterial activity was observed as the Sm concentration increased, compared to pristine nanoplates. The obtained results suggest that the synthesized Sm-incorporating α-MoO₃ 2D-layered nanoplate could be a potential antibacterial agent.