Investigation of the Influence of pH on the Microstructure, Morphology, Optical Properties, and Environmental Remediation Efficacy of Molybdenum Trioxide (MoO3) Nanoparticles

Molybdenum trioxide (MoO3) is a versatile transition metal oxide with promising applications in photocatalysis, optoelectronics, and antimicrobial systems due to its unique structural, optical, and electronic properties. In this study, undoped MoO3 was synthesized using a facile wet-chemical approach under varying pH conditions (9, 10, and 11). The samples were characterized using X-ray diffraction (XRD), Field emission Scanning electron microscopy (FE-SEM), Photoluminescence (PL), Ultraviolet-visible (UV-Vis) spectroscopy, and antibacterial activity tests. The structural and optical properties, including crystallinity, defect states, and bandgap energy, were investigated in detail. The XRD analysis revealed a slight variation in crystallite size and strain with pH, while the FE-SEM analysis highlighted the morphological transformations from layered structures to dispersed nanoparticles. PL and UV-Vis analyses demonstrated pH-dependent bandgap tuning and defect-mediated optical transitions. Finally, the antibacterial activity of MoO3 against Escherichia coli was evaluated, demonstrating enhanced bactericidal effects over time. These findings underscore the potential of MoO3 as a multifunctional material for environmental and biomedical applications.