Zn and N Codoped TiO2 Thin Films: Photocatalytic and Bactericidal Activity (original) (raw)
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Sulfur-doped titania thin films were prepared by atmospheric pressure chemical vapour deposition (APCVD) for the first time using titanium tetrachloride, ethyl acetate and carbon disulfide. The films were compared to two industrial self-cleaning products: ActivÔ and BIOCLEANÔ, and shown to be superior in both photocatalysis and photo-induced superhydrophilicity, two preferential properties of effective self-cleaning coatings. X-Ray diffraction showed the films have the anatase TiO 2 structure. XPS and EDX analysis shows changes in S : Ti ratio with preparative conditions indicating that sulfur has indeed been incorporated into the lattice. S-Doped TiO 2 films were found to be effective agents for killing the bacterium Escherichia coli using light sources commonly found in UK hospitals.
Photocatalytic antibacterial performance of Sn4+-doped TiO2 thin films on glass substrate
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Both N-doped and undoped thin films of 3SnO 2 /TiO 2 composite were prepared, by sol-gel and dip-coating methods, and then calcined at 600 ∘ C for 2 hours. The films were characterized by FTIR, XRD, UV-Vis, SEM, and XPS, and their photocatalytic activities to degrade methylene blue in solution were determined, expecting these activities to correlate with the inactivation of bacteria, which was confirmed. The doped and undoped films were tested for activities against Gram-negative Escherichia coli (E. coli) and Salmonella typhi (S. typhi), and Gram-positive Staphylococcus aureus (S. aureus). The effects of doping on these composite films included reduced energy band gap, high crystallinity of anatase phase, and small crystallite size as well as increased photocatalytic activity and water disinfection efficiency.
Applied Catalysis B-environmental, 2009
Nitrogen and sulfur co-doping has been achieved in the commercial TiO2 nanoparticles of anatase TKP 102 (Tayca) by grinding it with thiourea and calcinating at 400 °C. The successful substitutional N-doping and cationic/anionic S-doping were validated by XPS measurements. Diffuse reflectance spectroscopy (DRS) showed a marked broadening of the absorption spectrum of the doped material towards the visible range.Phenol and dichloroacetate (DCA) oxidation and Escherichia coli inactivation were achieved under UV illumination using the N, S co-doped TiO2 powders. Electron spin resonance (ESR) spin-trapping experiments showed that under UV light irradiation, the Moreover, under visible light (400–500 nm) illumination of N, S co-doped TiO2 a complete inactivation of E. coli bacteria was observed. In contrast, under such conditions, phenol was only partially degraded, whereas DCA was not at all affected. ESR experiments performed with N, S co-doped TiO2 powders illuminated with visible light and in the presence of singlet oxygen (1O2) quencher, TMP-OH, showed the formation of 1O2. This suggests that superoxide radical (
Applied Microbiology and Biotechnology, 2013
CuO nanostructures with different morphology were formed on copper substrate by in situ crystallization one-step process via chemical method at room temperature. The as-grown copper oxide nanostructure films were characterized using X-ray diffraction (XRD), Fourier transform-infra red spectroscopy (FT-IR) and scanning electron microscope (SEM) analysis. The XRD and FT-IR analysis confirm the formation of monoclinic CuO nanostructures. SEM images show gradual development of nanostructures of copper oxide with different morphology. A possible growth mechanism was also proposed here. The photo catalytic activity of this CuO nanostructure films was evaluated by monitoring the photo-degradation of salicylic acid. Also antibacterial activity of these films was studied against gram-positive and gram-negative bacteria's. Results demonstrated that CuO thin film possesses good photo catalytic as well as antibacterial activity. Being low cost and easily available material, CuO nanostructures might have promising applications in the field of environmental remediation for organic pollutant degradation.
World Journal of Microbiology and Biotechnology, 2009
This work focuses on the photocatalytic performances and antibacterial activity of nitrogen doped TiO 2 nanosystems with three and five layers obtained by a sol-gel route, followed by thermal treatment in oxygen or ammonia atmosphere at temperatures between 400 and 1000°C. Subsequently, the antibacterial activity of the obtained nanosystems on the Escherichia coli cells are determined and discussed. The obtained results show a significant dependence of the functional performances on the system's composition. In particular, the antimicrobial activity of nitrogen-doped TiO 2 films is correlated with the temperature of thermal treatment and illumination time with visible artificial light.
Photocatalytic disinfection of E . coli using N-doped TiO 2 composite
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Heterogeneous photocatalysis is among an alternative technique for the inactivation of pathogenic microorganisms. Several researchers have achieved the successful killing of bacteria, viruses, fungi or protozoa by semiconductor photocatalysis. This study significantally provides a better understanding of the bactericidal properties of N-TiO2 by identifying specific bacterial targets and cell strcuture during disinfection in pure water. The photocatalytic inactivation of bacteria was investigated using E. coli, a well-known bacterial indicator. Firstly, the effects of the contact of N-doped TiO2 with bacterial cells in the dark on both the bacterial cultivability and the envelope integrity was carried out. Then, assessment of the deleterious effects of N-doped TiO2 on the bacteria’s permeability and cultivability was done under visible radiations exposure. In order to identify the cell structure during the inactivation of the bacteria, monitoring of atomic force microscopy was also c...
Environmental Science and Pollution Research, 2014
Nanosilver-modified TiO 2 and ZnO photocatalysts were studied against methicillin-resistant Staphylococcus aureus on the surface and against naturally occurring airborne microorganisms. The photocatalysts/polymer nanohybrid films were prepared by spray coating technique on the surface of glass plates and on the inner surface of the reactive light source. The photoreactive surfaces were activated with visible light emitting LED light at λ=405 nm. The optical properties of the prepared photocatalyst/polymer nanohybrid films were characterized by diffuse reflectance measurements. The photocatalytic properties were verified with the degradation of ethanol by gas chromatography measurements. The destruction of the bacterial cell wall component was examined with transmission electron microscope. The antibacterial effect of the photocatalyst/polymer nanohybrid films was tested with different methods and with the associated standard ISO 27447:2009. With the photoreactive coatings, an extensive disinfectant film was developed and successfully prepared. The cell wall component of S. aureus was degraded after 1 h of illumination. The antibacterial effect of the nanohybrid films has been proven by measuring the decrease of the number of methicillin-resistant S. aureus on the surface and in the air as the function of illumination time. The photocatalyst/polymer nanohybrid films could inactivate 99.9 % of the investigated bacteria on different thin films after 2 h of illumination with visible light source. The reactive light source with the inner-coated photocatalyst could kill 96 % of naturally occurring airborne microorganisms after 48 h of visible light illumination in indoor air sample. The TEM results and the microbiological measurements were completed with toxicity tests carried out with Vibrio fischeri bioluminescence bacterium.
Titanium dioxide is a photocatalyst with well-known ability to oxidise a wide range of organic contaminants as well as to destroy microbial cells. In the present work TiO 2 nanoparticles with high specific surface area (150 m 2 /g) were used to prepare nanostructured films. The TiO 2 nanoparticle-based film in combination with UV-A illumination with intensity (22 W/m 2 ) comparable to that of the sunlight in the UV-A region was used to demonstrate light-induced antibacterial effects. Fast and effective inactivation of Escherichia coli cells on the prepared thin films was observed. Visualization of bacterial cells under scanning electron microscopy (SEM) showed enlargement of the cells, distortion of cellular membrane and possible leakage of cytoplasm after 10 min of exposure to photoactivated TiO 2 . According to the plate counts there were no viable cells as early as after 20 min of exposure to UV-A activated TiO 2 . In parallel to effects on bacterial cell viability and morphology, changes in saturated and unsaturated fatty acids -important components of bacterial cell membrane-were studied. Fast decomposition of saturated fatty acids and changes in chemical structure of unsaturated fatty acids were detected. Thus, we suggest that peroxidation and decomposition of membrane fatty acids could be one of the factors contributing to the morphological changes of bacteria observed under SEM, and ultimately, cell death.