The dissertation is devoted to establishing the mechanisms of influence of nanocrystals (NCs) with perovskite structure and laser-induced periodic surface structures (LIPSS) on electrochemiluminescent (ECL) and electrochemical properties of electrodes of electrochemical analytical systems. The mechanisms of formation of multicomponent NCs by pulsed laser ablation, which have the potential for their use in electrochemical analytical systems as modifiers of the surface of working electrodes, are studied.
Electrochemical research methods play an important role and have significant prospects in analytical research due to their inherent advantages such as sensitivity, ease of use, versatility and speed. Electrochemical analytical systems need not only improvement of the above parameters but also increase of accuracy, stability, reproducibility of measurement results, reactivity of electrodes, as well as expansion of the list of substances that can be detected, etc.
In classic electrochemiluminescent analytical systems, glassy carbon polished electrodes are widely used in combination with films that can contain a limited list of luminophores. In turn, known luminophores are not stable in all ECL systems due to the fact that they can degrade during repeated measurements, and also have a limited list of analytes with which they interact.
The formation and research of new materials with improved properties for modification of electrodes of electrochemical analytical systems can provide an expansion of the list of substances that can be detected and increase the intensity of the electrochemiluminescence reaction near the surface of the working electrode. The use of nanostructures to modify working electrodes is also a promising way to solve the problem of the instability of luminophores in liquids during cyclic voltammetry.
The use of materials with a perovskite structure opens up new possibilities in the tasks of electroanalytical chemistry. Perovskite nanocrystals are increasingly used in the fields of optoelectronics, solar energy, processing of harmful compounds, water splitting applications and have prospects for use in electrochemical analytical systems due to their strong and stable luminescence. Due to the peculiarities of the crystal structure, NCs with a perovskite structure have unique optical and electrophysical properties that can be adjusted by changing the material composition. Most often, perovskite NCs are synthesized by chemical methods, for example, hot-injection and ligand-assisted reprecipitation (LARP). Perovskite NCs synthesized by chemical methods for electrochemical studies of liquids have inherent disadvantages: instability in polar
solutions, which are widely used for ECL studies of biological samples; as well as the influence on the ECL measurement from the ligands that form NCs, on the substances that participate in the electrochemical reactions. The above-mentioned disadvantages of perovskite NCs can be eliminated using the following approaches: by increasing the reactivity of chemically synthesized NCs with UV irradiation followed by their stabilization with the help of polymers; by forming perovskite NCs by pulse laser ablation technique.
To study the stability and electrochemical properties of perovskite NCs, inorganic CsPbBr3 NCs with a perovskite structure, synthesized by the LARP method, were used. In order to obtain information about the stability, structural and optical characteristics of CsPbBr3 NCs under the influence of UV irradiation, the following methods were used: transmission electron microscopy (TEM), UV-Vis spectroscopy, cyclic voltammetry, ECL measurements. Before the modification of the working electrodes, the surface of the CsPbBr3 NPs was "activated" by short-term UV irradiation and stabilized by their incorporation into the polymethyl methacrylate (PMMA) polymer. Stabilized CsPbBr3 NPs were subsequently used to modify polished glassy carbon working electrodes in the form of thin films using spin-coating and drop-casting methods. The advantages of the spin-coating method for the formation of functional films with a thickness that does not
prevent the passage of the ECL reaction and with a uniform distribution of nanoparticles on the electrode surface have been established. The electrochemical properties of the working electrodes modified with functional films of CsPbBr3 NCs were investigated by the CVAM method in a phosphate buffer solution. ECL measurements using modified electrodes made it possible to establish that the effect of "activation" of CsPbBr3 NCs with the help of short-term UV irradiation provides a stable ECL signal with the co-reagent tripropylamine, which acts as a biological substance that is detected.
In order to obtain stable NCs with a perovskite structure by the method of pulsed laser ablation, the conditions for the synthesis of multicomponent crystalline nanostructures were investigated and formed.
