The membranes’ role is of supreme importance in the separation of compounds under different phases of matter. The topic addressed here is based on the use of membranes on the gases separation, specifically the advantages of mixed-matrix membranes (MMMs) when using carbon nanotubes as fillers to separate carbon dioxide (CO₂) from other carrier gas. MMMs consist of a polymer support with additive fillers to improve their efficiency by increasing both selectivity and permeability. The most promising fillers in the MMM development are nanostructured molecules. Due to the good prospects of carbon nanotubes (CNTs) as MMM fillers, this article aims to concentrate the advances and developments of CNT–MMM to separate gases, such as CO₂. The influence of functionalized CNT or mixtures of CNT with additional materials such as zeolites, hydrogel and, graphene sheets on membranes performance is highlighted in the present work.

Until now, the major problem of methane conversion is to break the very strong C-H bond. It is possible by employing some catalytic methods. However, the formation of carbon powder diminishes the catalytic performance. The use of a gliding arc, described in this work, has two objectives: the hydrogen production and other syngas such as acetylene, and the treatment of the green house gas methane. A good approximation model describing the chemical processes concerning the methane decomposition is described, first by the interaction of key radicals such as CH3 and H, followed by chemical reactions involving other hydrocarbons. Furthermore, the experimental results demonstrated the ability of the gliding arc to accelerate chemical reactions at low temperatures while decreasing energetic cost.

Electrodes and electrolytes are critical components for the performance of supercapacitors. In this study, supercapacitors with different interfaces were assembled using polypyrrole (PPy) or a polypyrrole–carbon nanotube (PPy-CNT) composite as active materials, and dimethyl sulfoxide (DMSO) and sodium chloride (NaCl) were used as electrolytes. Electrochemical measurements were obtained by cyclic voltammetry (CV) at a scan rate of 20 mV/s and galvanostatic charge–discharge (GCD) measurements at a scan rate of 50 µA/s. The results suggest that the supercapacitor with a PPy-CNT composite and NaCl electrolyte has promising electrochemical characteristics.

Boron-doped carbon nanotubes (B-doped NTs) are predicted to behave as semiconductors over a large range of diameters and chiralities and might thus constitute a suitable class of materials for nanoelectronics technology; they could be used, for example, to enhance properties of supercapacitors as capacitance and time of charge/discharge. In this paper, we propose an electric arc to synthesize B-doped NTs, based on the erosion of graphite electrodes with nickel and yttrium as catalysts and boron as the doping element. This technique allows obtaining carbon nanotubes (NTs) doped with around 8% of boron, in a short amount of time (2 min) and under relatively low applied power (2 kW). B-doped NTs were characterized with scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Physical properties of the plasma were also studied using optical emission spectroscopy. Temperatures of around 5000 K were obtained suggesting a high concentration of C ₂ molecules and then, the ideal conditions to synthesize NTs.

The purpose of this work is to suggest the conception of a supercapacitor using environment-friendly materials, in addition to exhibiting good electrochemical performances. In order to lower the environmental footprint of supercapacitors, one current attempt in the literature is to replace efficient but toxic organic electrolytes by harmless, bio-friendly electrolytes such as a mixture of sodium salt with a hydrogel. However, those bio-friendly electrolytes have not been demonstrated yet to be a relevant alternative, as they are still not able of similar performances as toxic organic electrolytes. The work reported in this paper demonstrates, as a different approach, that the capacitance of a bio-friendly, hydrogel-based electrolyte combined with sodium salt can be significantly increased by adding carbon nanotubes (CNTs) to the gel. As a result, the supercapacitor using the CNT-loaded bio-friendly electrolyte has registered not only an enhanced capacitance, but also better energy and power densities compared to both the same but CNT-free electrolyte, and a toxic DMSO-based organic electrolyte.