It is still problematic to define a direct relationship between specific properties of a nanostructured surface (e.g., wettability) and its morphology. Not surprisingly, scientists continue to explore en masse the cut‐and‐try method. In this work, new insights are presented into the correlation of functional properties of the complex nanocomposites with their morphological characteristics. Using polyethylene‐terephthalate (PET) as a model material due to its importance and wide use in experiments, super‐hydrophilic nanocomposites amenable to be used in a variety of industrial applications are first developed, by exposing PET samples to oxygen plasma under controlled conditions. The morphology of the surfaces is confirmed using AFM and SEM techniques, and wettability in air and its oleophobic properties in water using contact angle and roll‐off measurements. Next, different analytical tools such as Minkowski connectivity (Euler‐Poincaré characteristic), Hough distributions and 2D FFT are applied to study ordering, connectivity, and fractal characteristics of the samples. It is concluded that fractal dimension, along with ordering and connectivity, are among the major characteristics of the nanocomposite that determine many important physical and chemical properties of the functional nanomaterials, and the fractal dimension could be a target morphological feature to inform the design of fabrication technology.

In this study, we examine the statistical properties of asymmetric surface dielectric barrier discharges (SDBD) produced by applying a periodic high voltage between two conducting displaced electrodes, located at the opposite sides of a flat dielectric panel. Here, the asymmetry refers to the fact that the lower electrode is fully covered with an insulating material, while the upper one, glued onto the dielectric surface, is otherwise left exposed to the air. Such a configuration allows the formation of a thin layer of plasma above the insulating surface. A single cycle signal consists of two well-separated half-cycle patterns, denoted as forward and backward strokes, corresponding to positive and negative voltages, respectively. They display a quite complex discharge pattern constituted by a sequence of individual peaks (bursts) of varying current and time duration. Specifically, we find that backward stroke bursts carry a positive mean charge Q≃0.3 nC and mean current I≃35 mA, with a mean duration τ≃15 ns, while forward stroke bursts have a negative mean charge Q≃−0.1 nC, a mean current I≃−20 mA, and a mean duration τ≃11 ns. The statistical analysis suggests that power injection can be tailored to produce the active agents in the plasma needed for a particular application. We also determined discharge spatial correlation patterns from measurements of the associated stimulated optical emission. The optical excitations occur as a result of the ionizing effect of the electromagnetic waves which ignite the discharge, followed by the electric current flow. In particular, we point out that one of the phases of the discharge is compatible with a cathode directed streamer phenomenon (backward stroke), while the mechanism acting for a forward stroke has a different structure.

Plasma-assisted supersonic jet deposition (PA-SJD) is a precise technique for the fabrication of thin films with a desired nanostructured morphology. In this work, we used quadrupole mass spectrometry of the neutral species in the jet and the extensive characterization of TiO2 films to improve our understanding of the relationship between jet chemistry and film properties. To do this, an organo-metallic precursor (titanium tetra–isopropoxide or TTIP) was first dissociated using a reactive argon-oxygen plasma in a vacuum chamber and then delivered into a second, lower pressure chamber through a nozzle. The pressure difference between the two chambers generated a supersonic jet carrying nanoparticles of TiO2 in the second chamber, and these were deposited onto the surface of a substrate located few centimeters away from the nozzle. The nucleation/aggregation of the jet nanoparticles could be accurately tuned by a suitable choice of control parameters in order to produce the required structures. We demonstrate that high-quality films of up to several µm in thickness and covering a surface area of few cm2 can be effectively produced using this PA-SJD technique.

We compared spectra and intensity light of different sources, such as a UV-A lamp, a UV-C lamp, and a visible bulb, and atmospheric nonthermal plasma emission. Spectroscopic measurements were performed with an optical emission spectrometer and radiometric measurements with a radiometer to which UV-A, UV-C, and visible probes were coupled to measure the light intensity per unit surface. For each light source, we measured the emission spectrum and light intensity using different probes and also varying the relative distance. The nonthermal atmospheric plasma was generated by means of a surface barrier dielectric discharge varying the relevant parameters. This work allowed us to create the experimental setup suitable for further studies on volatile organic compound abatement by plasma-catalysis processing and compared it to the photocatalysis techniques based on UV and visible lamps.

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In this work, a novel 0D model for the evaluation of O3 and NO2 produced by a Surface Dielectric Barrier Discharge (SDBD) in a closed environment is presented. The model is composed by two coupled sub-models, a discharge sub-model and an afterglow one. The first one, simulating the discharge regime and consequently including electron impact reactions, aims to calculate the production rates of a set of key species (atomic oxygen, excited states of molecular oxygen and molecular nitrogen). These latter are the input of the afterglow sub-model, that simulates the afterglow regime. We introduce a methodology to relate the production rates of the above mentioned species to the input power of the SDBD reactor. The simulation results are validated by a comparison with experimental data from absorption spectroscopy.
The experimental measurements are carried out as follows. First, the discharge is turned on until the NO2 number density reaches steady state. Then, the discharge is turned off for several minutes. Finally, the discharge is turned on again to observe the effects of the NO2 concentration on ozone dynamics. The entire process is done without opening the box. The system is simulated in the computational domain when operating in all the above-listed conditions, for three different levels of input power.

Our work is aimed at studying the abatement of volatile organic compounds produced by photocatalysts working in different light spectra, investigating the best catalyst able to treat propane in air mixtures at high concentrations of the order of thousands of ppm. The experimental data were analyzed in order to extract the relevant parameters and to compare the catalytic activities of three different photocatalysts, TiO2, WO3, and their mixtures. In a reactor box of 1.5 l, photocatalysis processing with TiO2 catalysts gave the best propane depletion of the order of 10% for initial propane concentrations of up to 5000 ppm after 22 min and UV-A lamps with an intensity of 0.4 mW/cm2 while the TiO2 and WO3 catalysts produced an abatement of about 5% after 22 min using UV-C light at an intensity of 5 × 102 mW/cm2.

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