The review is devoted to the methods of introducing aryl functional groups to the CNT surface. Arylated nanotubes are characterized by extended solubility, and are widely used in photoelectronics, semiconductor technology, and bioelectrocatalysis. The main emphasis is on arylation methods according to the radical mechanism, such as the Gomberg–Bachmann and Billups reactions, and the decomposition of peroxides. At the same time, less common approaches are also considered. For each of the described reactions, a mechanism is presented in the context of the effect on the properties of functionalized nanotubes and their application. As a result, this will allow us to choose the optimal modification method for specific practical tasks.

This study was carried out in order to assess several modifications of carbon nanotube-based nanomaterials for their applications in laccase electrodes and model biofuel cells. The modified MWCNTs served as adapters for the immobilization of laccase from Catenuloplanes japonicus VKM Ac-875 on the surface of electrodes made of graphite rods and graphite paste. The electrochemical properties of the electrodes were tested in linear and cyclic voltammetrical measurements for the determination of the redox potential of the enzyme and achievable current densities. The redox potential of the enzyme was above 500 mV versus NHE, while the highest current densities reached hundreds of µA/cm². Model biofuel cells on the base of the laccase cathodes had maximal power values from 0.4 to 2 µW. The possibility of practical application of such BFCs was discussed.

Various methods for determining molecular diffusion coefficients have been evaluated and compared for a range of different chemical compounds. It was shown that electrochemical methods have a larger error compared to non-electrochemical methods. A critical analysis of the molecular volumes obtained by quantum chemical modeling at the semi-empirical level showed that the PM6-D3 method was the most accurate for calculating the diffusion coefficients. The results obtained using the PM6-D3 Hamiltonian correlated with experimental data and the results of calculations using the ABC method (R = 0.99). Among the six equations relating the diffusion coefficient to molecular volume, the Hayduk-Laudie equation was found to have an error of less than 8%, which is comparable to the error in determining this parameter experimentally. Thus, this model allows accurate theoretical predictions of diffusion coefficients for inorganic ions, macromolecules, and carbon nanomaterials, provided that the structure of the molecule/nanoparticle is sufficiently rigid.

Plant microbial fuel cells (PMFC) offer a promising alternative to traditional electricity sources. However, their practical application is limited due to poor electrochemical performance, which is enhanced using various electrode modifications. In this study, MnO₂ was electrochemically deposited on the surface of carbon felt and then used as a bifunctional material for the anode and cathode configurations in PMFC systems. The modified carbon felt samples were characterized in terms of electrochemically active surface area and the number of defects determined using cyclic voltammetry and Raman spectroscopy. The resulting density power was 15, 2, and 33 mW/m² for the control system, PMFC-anode-MnO₂, and PMFC-cathodeMnO₂, respectively. Thus, the deposition of MnO₂ on the cathode in PMFC systems results in a twofold increase of electrical energy generation.

The stages of electrochemical polymerization of the 1,10-phenanthroline complex with Fe²⁺ ([Fe(phen)₃]²⁺) were studied using cyclic voltammetry. It was found that the oxidation of [Fe(phen)₃]²⁺ involves four electrons, resulting in the formation of free radicals. The recombination of these radicals is the main mechanism of polymerization, as confirmed by the rate order of the reaction. Poly-(1,10-phenanthroline) undergoes Fenton hydroxylation, creating redox-active sites in the polymer structure. This increases its electrical conductivity. The modification of an electrode with a polymer containing poly-(1,10-phenanthroline) and sulfanylic acid yielded the most promising results, increasing the number of active sites and shifting the reduction potential to more positive values. The electrochemical behavior of poly-(1,10-phenanthroline)-modified electrodes in relation to various redox systems has revealed the highest electrocatalytic activity towards the I₂/I⁻ redox couple. This makes this material promising for application in fuel cells.