Carbon nanotubes (CNTs) play a unique role in the area of flexible conductors as they have remarkably high electrical conductivity and bend easily without deformation. Consequently, CNTs are commonly deposited on substrates as conductive tracks/coatings. Halogenated solvents are often employed to facilitate the deposition process because they dry rapidly due to their high volatility. In this work, we report that halogenated solvents can dope CNTs considerably. The study showed that the use of dichloromethane, chloroform, or bromoform for the CNT deposition significantly impacts the chemical potential of the material, thereby modifying its charge transport characteristics. As a consequence, up to four-fold improvement in electrical conductivity is noted due to doping.

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Nickel behavior has a significant role in the electrorefining of copper, and although it has been extensively studied from the anode and electrolyte point of view over the past decades, studies on nickel contamination at the cathode are limited. In the current paper, three possible contamination mechanisms—particle entrapment, electrolyte inclusions and co-electrodeposition—were investigated. Copper electrorefining (Cu-ER) was conducted at the laboratory scale, and the cathodes were analyzed by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and flame atomic absorption spectroscopy (AAS). Particle entrapment was studied by adding NiO and Fe2O3 to the system to simulate nickel anode slime, and the experiments were replicated with industrial anode slime material. The possibility of electrolyte entrapment due to nodulation was explored through the addition of graphite to produce nodules on the cathode. Co-electrodeposition was analyzed by experiments that utilized a Hull cell. The results indicate that particle entrapment can occur at the cathode and is a major source of the nickel contamination in Cu-ER, whereas nickel compounds were not shown to promote nodulation. Inclusions of bulk electrolytes within the surface matrix were observed, proving that electrolyte entrapment is possible. As co-electrodeposition of Ni in Cu-ER is thermodynamically unlikely, these experimental results also verify that it does not occur to any significant extent.

Promising electrical properties of single-walled carbon nanotubes (SWCNTs) open a spectrum of applications for this material. As the SWCNT electronic characteristics respond well to the presence of various analytes, this makes them highly sensitive sensors. In this contribution, selected organophosphorus compounds were detected by studying their impact on the electronic properties of the nanocarbon network. The goal was to untangle the n-doping mechanism behind the beneficial effect of organic phosphine derivatives on the electrical conductivity of SWCNT networks. The highest sensitivity was obtained in the case of the application of 1,6-Bis(diphenylphoshpino)hexane. Consequently, free-standing SWCNT films experienced a four-fold improvement to the electrical conductivity from 272 ± 21 to 1010 ± 44 S/cm and an order of magnitude increase in the power factor. This was ascribed to the beneficial action of electron-rich phenyl moieties linked with a long alkyl chain, making the dopant interact well with SWCNTs.

Carbon nanotubes (CNTs) have a wide range of unique properties, which have kept them at the forefront of research in recent decades. Due to their electrical and thermal characteristics, they are often evaluated as key components of thermogenerators. One can create thermogenerators exclusively from CNTs, without any metal counterpart, by properly selecting dopants to obtain n- and p-doped CNTs. However, the performance of CNT thermogenerators remains insufficient to reach wide commercial implementation. This study shows that molecular doping and the inclusion of ZnO nanowires (NWs) can greatly increase their application potential. Moreover, prototype modules, based on single-walled CNTs (SWCNTs), ZnO NWs, polyethyleneimine, and triazole, reveal notable capabilities for generating electrical energy, while ensuring fully scalable performance. Upon doping and the addition of ZnO nanowires, the electrical conductivity of pure SWCNTs (211 S/cm) was increased by a factor of three. Moreover, the proposed strategy enhanced the Power Factor values from 18.99 (unmodified SWCNTs) to 34.9 and 42.91 µW/m∙K2 for CNTs triazole and polyethyleneimine + ZnO NWs inclusion, respectively.