Thèses de doctorat

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Browsing Thèses de doctorat by Subject "Antibacterial coating, photocatalyst,"

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    Elaboration, functionalization and characterisation of modified titanium oxide thin films for antibacterial performance
    (University of 20 Août 1955 Skikda, 2024) GRINE ,DJIHAD; Akkari ,Hocine
    Antibacterial coating technology is a cutting-edge innovation that plays a vital role in reducing the risk of bacterial transmission and contamination, thereby enhancing public health and safety. In this context, this work aims to create a novel antibacterial coating based on the Ag-TiO2-Fe system. Various films of TiO2, TiO2-Fe, and Ag-TiO2-Fe composites thin films with varying silver contents were prepared via thermal evaporation method. The effect of the incorporation of Fe (5 wt%) and Ag with different content (from 5 to 20 wt%) on the structural, morphological, optical, and luminescent properties of TiO2 thin film and how they affect the antibacterial performance was investigated. The films were characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV–vis–NIR spectroscopy, and photoluminescence (PL). The antibacterial efficiency of the prepared films against Escherichia coli is examined both in the dark and under UV light. The results demonstrate that the addition of silver in TiO2-Fe lead the formation of the anatase crystalline phase. SEM images confirmed the presence of silver in its metallic state with different particles sizes ranging from 70 to 400 nm in the composite films. It is found that the band gap energy of TiO2-Fe and Ag-TiO2-Fe composite films with different Ag content (5-20 wt%) decreased compared to pure TiO2 film, we also noted a reduction in photoluminescence intensities with the addition of Fe and Ag to TiO2 matrix and the reduction was significant at higher silver content, this indicates a low rate of electron-hole pair recombination, therefore charge separation is promoted, resulting in enhancement in the photokilling activity. Antibacterial tests against E.coli showed that silver significantly improved antibacterial efficiency of the Ag-TiO2-Fe composite films in the dark (87, 94, and 100% for 10, 15, and 20 wt%), respectively. Under UV light, Ag-TiO2-Fe composite films exhibited excellent photokilling activity of E.coli compared to pure TiO2 and TiO2-Fe films up to 81% for 5 wt% Ag, and 100% for 10, 15, and 20 wt% Ag-TiO2-Fe composite films due to the synergistic effect that arises between Ag- and Fe-modified TiO2. These results indicate the effectiveness of the AgTiO2-Fe system as a promising antibacterial coating for use in medical and environmental applications