Tailoring preparation, structure and photocatalytic activity of layer-by-layer films for degradation of different target molecules

Virtually Transparent TiO2/Polyelectrolyte Thin Multilayer Films as High-Efficiency Nanoporous Photocatalytic Coatings for Breaking Down Formic Acid and for Escherichia coli Removal

“…The SEM images of the PEI/(PSS/TiO2)n films showed the homogeneity of the films at the micrometer scale, whatever the number of layer pairs, while on the contrary they clearly revealed their heterogeneity at the nanometric scale, which provides to the films their porous structure, as visualized on both top-view and cross-section images (Figures 2 and 3). This porous structure was also observed on PSS/TiO2 LbL films on different substrates in the works of Rongé et al 33 and Dontsova et al 32 While a fairly good coverage of the silicon wafer by TiO2 nanoparticles was already observed for a single layer pair film, the cross sections images did not show any stratified structure with well-defined polyelectrolyte and titania layers, and the surface coverage became total and the films became denser with the increase in the number of layer pairs (Figure 3). An average thickness increase of 43 nm per layer pair was derived from the film cross section analysis, in agreement with the ellipsometry results (Table 2 and Figure 1B).…”

“…This can also be put into perspective with Rongé et al, who correlated a decrease in the apparent kinetic rate constant for methylene blue degradation when increasing the layer pair deposition time, to the construction of denser TiO2/polyelectrolyte films. 33 Upon the addition of layers, the film structure was reported to be self-organized and to become more compact, with a reduction of the film's porosity.…”

“…13,19−27 Furthermore, the amphoteric properties of most photocatalytic materials (e.g., titania) favor their versatile incorporation within multilayer films, by allowing negatively or positively charged titania suspensions to be prepared by suitably adjusting the pH acidic or alkaline media. 13,28 Some of the recent investigations of photocatalytic LbL films concern the gas-phase heterogeneous photocatalytic oxidation for the mineralization of air pollutants such as 2-propanol, 29,30 acetaldehyde, 31 hydrogen sulfide, 32 or ammonia, 33 as well as chloroethyl ethyl sulfide as a model of a chemical warfare agent. 34 The elaboration of antibacterial photocatalytic surfaces has also been studied for developing self-disinfecting textiles.…”

Development of an electron paramagnetic resonance methodology for studying the photo-generation of reactive species in semiconductor nano-particle assembled films

“…Therefore, thin flat cells or sub-millimetre capillaries are required to perform EPR measurements. In this work, thanks to electrostatic interaction as driving forces, controlled hybrid coatings composed of polyelectrolyte and TiO2 nano-particles (nano-TiO2) 24,25 were achieved on the inner walls of capillaries by stepwise formation 26 , also referred as layer-by-layer approach 27,28 . This method is an established tool for preparing nano-particle-containing films in which the nano-particle deposit architecture can be well controlled.…”

Glucose-induced decomposition of layer-by-layer films composed of phenylboronic acid-bearing poly(allylamine) and poly(vinyl alcohol) under physiological conditions

“…Layer-by-layer (LbL)-deposited multilayer films have been widely studied because of their potential applications in chemical and biomedical devices, such as separators, 1 coatings, 2 catalysis, 3 sensors, 4 and drug delivery systems. [5][6][7] Among the LbL films, stimuli-sensitive films, the structures and functions of which change in response to external stimuli, are of special interest in the development of thin film devices.…”