Coffee Extract Mediated Foam-Structured Cerium Dioxide Nanoparticles: Green Synthesis and Enhanced Photocatalytic Bactericidal Efficiency

For the first time, cerium dioxide CeO 2 nanoparticles with a foamy porous structure were prepared by green synthesis using coffee extract as a reducing and stabilising agent, and the porous CeO 2 photocatalysts were used for sterilisation. X-ray photoelectron spectroscopy (XPS) analysis confirmed the binding energies of the elements C1s, O1s, and Ce3d. Scanning electron microscope (SEM) and Transmission Electron Microscope (TEM)analysis revealed a highly porous and foam-like structure of CeO 2 . Ce−O stretching bands were observed by Fourier Transform Infrared Spectrometer (FT-IR) and Raman spectroscopy. The band gap of CeO 2 was estimated to be 3.24 eV by UV–Visible spectrum. Photocatalytic bactericidal efficacy of foam-structured CeO 2 was evaluated against bacteria. It was observed that CeO 2 exhibit a significant bactericidal effect against G + and G – bacteria as compared to spherical-structured CeO 2 prepared by conventional hydrothermal synthesis. The bactericidal characteristics and features of CeO 2 photocatalyst are attributed to the fact that the as synthesized porous structured promote the use of light and induces the enhanced production of reactive oxygen species (ROS), which in turn cause lipid peroxidation, membrane damage and ultimately kill bacteria.