Indoor Light Enhanced Photocatalytic Ultra-Thin Films on Flexible Non-Heat Resistant Substrates Reducing Bacterial Infection Risks

Abstract

Photocatalytic antibacterial sol-gel coated substrates have been reported to kill bacteria under light or in the dark. These coatings showed non-uniform distribution, poor adhesion to the substrate and short effective lifetime as antibacterial surfaces. These serious limitations to the performance/stability retard the potential application of antibacterial films on a wide range of surfaces in hospital facilities and public places. Here, the preparation, testing and performance of flexible ultra-thin films prepared by direct current magnetron sputtering (DCMS) at different energies are reviewed. This review reports the recent advancements in the preparation of highly adhesive photocatalytic coatings prepared by up to date sputtering technology: High Power Impulse Magnetron Sputtering (HIPIMS). These latter films demonstrated an accelerated antibacterial capability compared to thicker films prepared by DCMS leading to materials saving. Nanoparticulates of Ti and Cu have been shown during the last decades to possess high oxidative redox potentials leading to bacterial inactivation kinetics in the minute range. In the case of TiO 2 -CuO x films, the kinetics of abatement of Escherichia coli (E. coli) and methicillin resistant Staphylococcus aureus (MRSA) were enhanced under indoor visible light and were perceived to occur within few minutes. Oligodynamic effect was seen to be responsible for bacterial inactivation by the small amount of released material in the dark and/or under light as detected by inductively-coupled plasma mass spectrometry (ICP-MS). The spectral absorbance (detected by Diffuse Reflectance Spectroscopy (DRS)) was also seen to slightly shift to the visible region based on the preparation method.

Innovative and stable TiO 2 supported catalytic surfaces removing aldehydes under UV-light irradiation

“…These rates were similar to the values reported for some VOCs [11][12][13][14]. We suggest that the degradation mechanism of the aldehydes on supported-TiO 2 involve TiO 2 electrons in the conduction band (cb) reacting with adsorbed O 2 on the TiO 2 yielding HO 2° radical-anions and other highly oxidative protonated radicals leading to the oxidation of the aldehydes [10,[21][22][23].…”

Metal–organic frameworks in a blended polythiophene hybrid film with surface-mediated vertical phase separation for the fabrication of a humidity sensor

“…Hybrid lms delaminated from three different substrates were sputtered using an Ar ion gun to eliminate the lm. 43 As the lm was etched for 1 min, the thickness of the lm decreased by about 15 nm. The Cu signal, which corresponded to HKUST-1, was collected at each thickness and is shown in Fig.…”

Bacterial adhesion and inactivation on Ag decorated TiO2-nanotubes under visible light: Effect of the nanotubes geometry on the photocatalytic activity

“…Additionally, Titanium dioxide (TiO2) is attracting great attention during the last decades because of its chemical stability, non-toxicity, high oxidative power and low fabrication cost [5]. Titanium based photocatalysts have been used to inactivate bacteria (in the dark or under light irradiation) [9][10], virus [11] and even cancer cells/tumor [3][4][5][6]. However, the wide band gap energy (3.2 eV) and the high recombination rate of the photo-generated charges in TiO2 reduces its photocatalytic performance.…”

“…Thus, it is necessity today to develop alternative ways to disinfect surfaces in hospital facilities since healthcare acquired infections are increasingly threatening our lives [5][6][7].…”