The detection of hazardous gases at different concentration levels at low and room temperature is still an actual and challenging task. In this paper, Al-doped ZnO thin films are synthesized by the electrochemical deposition method on the gold electrodes of AT-cut quartz resonators, vibrating at 10 MHz. The average roughness, surface morphology and gas sensing properties are investigated. The average roughness of Al-doped ZnO layers strongly depends on the amount of the doping agent Al₂(SO₄)₃ added to the solution. The structural dependence of these films with varying Al concentrations is evident from the scanning electron microscopy images. The sensing properties to ethanol and ammonia analytes were tested in the range of 0–12,800 ppm. In the analysis of the sensitivity to ammonia, a dependence on the concentration of the added Al₂(SO₄)₃ in the electrochemically deposited layers is also observed, as the most sensitive layer is at 3 × 10⁻⁵ M. The sensitivity and the detection limit in case of ammonia are, respectively, 0.03 Hz/ppm and 100 ppm for the optimal doping concentration. The sensitivity depends on the active surface area of the layers, with those with a more developed surface being more sensitive. Al-doped ZnO layers showed a good long-term stability and reproducibility towards ammonia and ethanol gases. In the case of ethanol, the sensitivity is an order lower than that for ammonia, as those deposited with Al₂(SO₄)₃ do not practically react to ethanol.

The present study investigates the possibility of obtaining graphene-like phases (defected graphene, graphene oxide, and reduced graphene oxide) as fine suspensions by applying a novel pulsed laser ablation (PLA) approach in flow mode. Two types of suspensions of microcrystalline graphite in aqueous suspensions and two types of microcrystalline graphite in suspensions of 6% hydrogen peroxide solution were irradiated in a quartz tube through which they flow. The third (λ = 355 nm) and fourth harmonics (λ = 266 nm) of an Nd:YAG laser system (15 ns pulse duration and 10 Hz pulse repetition rate) were used. The morphology of the obtained particles was studied by transmission electron microscopy (TEM). Their phase composition and structure were explored by X-ray photoelectron spectroscopy, X-ray diffractometry, and Raman spectroscopy.

Black powders were prepared from chimney soot by means of treatment with different solvents and drying. The powders were used to prepare inks, which were deposited on copper foils. The as prepared electrodes were assembled as supercapacitor structures with KOH as electrolyte. The charge-discharge characteristics were measured to evaluate the electrical capacitance and to compare the technology for soot treatment. The soot was studied as a source before and after treatment using IR spectroscopy, XRD and SEM EDX.

A polymerization procedure is presented to increase the molecular weight of hydrocarbons in household chimney soot without thermal treatment at high temperatures. Pristine soot was subject to chlorination, with half of it treated with magnesium (Mg-plates) to create random-type Grignard reagents (R-Mg-Cl) in diethyl ether media. Mixing the Grignard reagent and the rest of the halogenated soot material created new C-C bonds, thus increasing the molecular weight of the final product. The obtained stochastically polymerized soot (SPS) was investigated using Raman spectroscopy, FTIR spectroscopy and XPS and was subjected to electrochemical testing as an assembled supercapacitor with a KOH electrolyte. Results show significant carbon structure differences due to the chemical procedures and newly created functional groups in the soot. Such functional groups could increase the capacity of supercapacitors, creating pseudo-capacitance by participating in redox reactions. The results also unveiled removing any random contaminations in the pristine soot and obtaining a more uniform final product containing hydrocarbons with longer chains, thus increasing the molecular weight.