Polystyrene CuO/Cu2O uniform films inducing MB-degradation under sunlight

This study reports on a Cu-sputtered film on polystyrene (PS) leading to the discoloration/degradation of methylene blue (MB) under low intensity solar simulated irradiation. Direct current magnetron sputtering (DCMS) was used to graft uniform, adhesive Cu/Cu oxides on the polystyrene substrate. The kinetics of Cu-PS mediated MB-discoloration adding H2O2 was observed to take place within 90-120 min. The surface potential and pH variation was followed on the Cu-PS surface during MB-discoloration. Insight is provided for the observed changes relating them to the dye discoloration mechanism. The concentration, mean-free path and lifetime of the oxidative radical leading to MB-degradation were estimated. The Cu/Cu-oxides on the PS were characterized by X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) evidence for redox catalysis involving Cu(I)/Cu(II)-species was detected during MB-discoloration. Also by XPS the surface atomic percentage concentration was determined for the topmost Cu-PS layers. The Cu-PS coatings were also investigated for their optical and crystallographic properties. (C) 2016 Elsevier B.V. All rights reserved

Design, testing and characterization of innovative TiN–TiO2 surfaces inactivating bacteria under low intensity visible light

Ti was sputtered in a plasma chamber under a N2 atmosphere, depositing TiN films on polyester fibers. These films show a significant adsorption in the visible spectral region. A TiN layer 50 nm thick sputtered for 3 min under low intensity/actinic visible light led to the fastest bacterial inactivation (120 min). These innovative TiN nanoparticulate films were characterized by XPS, DRS and TEM

Antibacterial Ag-ZrN surfaces promoted by subnanometric ZrN-clusters deposited by reactive pulsed magnetron sputtering

Ag-ZrN films were deposited on polyester by direct current pulsed magnetron sputtering (from now on DCMSP) in Ar + N-2 atmosphere. ZrN on the polyester surface interacts with Ag leading to Ag-ZrN films. These composite films were more active in Escherichia coli inactivation compared to the Ag-films by themselves. The E. coli inactivation kinetics on Ag-ZrN polyester surfaces was accelerated >4 times compared to samples sputtering only Ag. Sputtering Zr in N-2 atmosphere presented no antibacterial activity by itself when applied for short times (20s agglomerated to bigger units leading to longer bacterial inactivation times. The Ag-atoms are shown to be immiscible with the ZrN-layer. The increase in thickness of the Ag-ZrN at longer sputtering times lead to a concomitant increase in rugosity and hydrophobic character of the Ag-ZrN sputtered layers. Several up-to date techniques have been used to characterize the catalytic Ag-ZrN film providing a full description of its structure. The Ag-ZrN films showed a uniform metal distribution and a semi-transparent gray-brown color. (C) 2011 Elsevier B.V. All rights reserved

Innovative TiO2/Cu Nanosurfaces Inactivating Bacteria in the Minute Range under Low-Intensity Actinic Light

The bacterial inactivation of E. coli by cotton TiO2/Cu DC-magnetron sputtered thin films was investigated in the dark and under low-intensity actinic light. The TiO2/Cu sputtered layers revealed to be sensitive to actinic light showing the spectral characteristics of Cu/CuO. This indicates that Cu does not substitute Ti4+ in the crystal lattice. Under diffuse actinic light (4 mW/cm2), the hybrid composite TiO2/Cu sample lead to fast bacterial inactivation times <5 min. This study presents evidence for a direct relation between the film optical absorption obtained by diffuse reflectance spectroscopy (DRS) and the bacterial inactivation kinetics by the TiO2/Cu samples. The Cu-ions inactivating the bacteria were followed in solution by inductively plasma coupled spectroscopy (ICPS). The amounts of Cu-ions detected by ICPS provide the evidence for an oligodynamic antibacterial effect. The changes in the oxidation state of Cu during bacterial inactivation were followed by XPS. The E. coli cell viability was detected by standard coliform counting CFU methods. The TiO2/Cu thickness layer was determined by profilometry and the film microstructure by XPS, TEM, AFM, XRD, XRF and contact angle (CA). A mechanism of bacterial inactivation by TiO2/Cu samples is suggested in terms of interfacial charge transfer (IFCT) involving charge transfer between TiO2 and Cu

Effect of the spectral properties of TiO2, Cu, TiO2/Cu sputtered films on the bacterial inactivation under low intensity actinic light

Bacterial inactivation by TiO2, Cu and TiO2/Cu DC-magnetron sputtered thin films was systematically investigated in the dark and under low intensity visible/actinic light. Low intensity actinic light led to a fast 6log10 (complete) bacterial inactivation within the minute range. The TiO2/Cu bifunctional composite films led to the fastest bacterial inactivation. The Cu sputtered on the TiO2 enabled the absorption of visible light by the supported film and triggered a photo-induced IFCT effect from TiO2 to the Cu/Cu-ions. Evidence for a direct relation between the films optical absorption obtained by diffuse reflection spectroscopy (DRS) and the bacterial inactivation kinetics (CFU) is presented. The film microstructure was characterized by X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS). The Tiand Cu-ions in solution were followed by inductive coupled plasma spectroscopy (ICPS). The small amount of Cu-ions determined by ICPS provide the evidence for an oligodynamic effect during bacterial inactivation. The Cu-redox changes and the ratio of the oxidized C /reduced C species were determined by XPS within the bacterial inactivation time

RF-plasma pretreatment of surfaces leading to TiO2 coatings with improved optical absorption and OH-radical production

Evidence is presented for the RF pretreatment of polyester enhances the TiO2 coating generation of oxidative species/radicals under a low level actinic light irradiation. After 30 min RF-plasma pretreatment of the polyester samples, the fastest bacterial inactivation was observed concomitant with a) the largest ratio of surface oxidized to the reduced functionalities as determined by XPS, b) a strong sample optical absorption as seen by DRS and c) the highest concentration surface OHradicals monitoring the fluorescence of the hydroxy-terephthalic acid. Evidence for the photocatalyst self-cleaning was found by XPS due to the lack of accumulation of bacterial residues on the polyester-TiO2. A further proof of self-cleaning was the ability by the polyester-TiO2 samples to inactivate again bacterial charge at the end of an inactivation cycle. By XPS evidence is presented for the Ti4+/Ti3+ related redox catalysis and the details of the the C and O-functionalities. Surface techniques such as: XRF; DRS; TEM; contact angle (CA); XRD and XPS, were applied to relate the microstructure of the TiO2 coatings with the destruction of E. coli taken as a probe

Modification of titania nanoparticles for photocatalytic antibacterial activity via a colloidal route with glycine and subsequent annealing

International audienceChanges in the colloid-chemical and photocatalytic properties of titania nanoparticles by attrition milling in the presence of glycine (Gly) and subsequent heat treatment were examined. By milling at 1500 rpm for 6 h, the average particle size was decreased from 123 to 85 nm, with simultaneous decrease in the specific surface area from 35.1 to 23.5 m2/g. Interfacial reactions between titania and Gly were confirmed by Fourier transform infrared spectroscopy, from the blue shift of the COO related vibrational bands by 25 cm 1, relative to the same band from the pristine Gly. The bimodal N1s x-ray photoelectron spectroscopy peak similar to that from the reported titania--amino acid complex is another indication of the complex formation with the participation of nitrogen. When the dispersion was dried and calcined at 500 °C in air, the powder exhibited pale yellow color. Diffuse reflectance spectroscopy showed significant visible light absorption, suggesting nitrogen incorporation into titania. The fired product showed high photocatalytic antibacterial activity by irradiation of blue light centered at around 440 nm, using Escherichia coli as a specimen of bacterial species. Thus, the present Gly-modified titania nanoparticles could be used for eliminating indoor bacteria under soft blue illumination. The series of interfacial chemical processes involved are also discussed