Philipp Yu. Gorobtsov

Using titanium and europium alkoxoacetylacetonates, oxides of the composition TiO₂ : xEu (where x = 0–10 at %) were prepared. The process of hydrolysis and polycondensation of alkoxoacetylacetonates of these metals was studied, and it was found that the addition of a small amount of europium significantly accelerates hydrolysis, but an increase in the concentration of the europium complex slows down this process. The hydrolysis and polycondensation products were subjected to solvothermal treatment. The resulting powders had an anatase structure, without impurities of europium oxide or other polymorphic modifications of TiO₂. The size of the coherent scattering region (CSR) of powders increases with the europium content in the system: from 6–7 nm (0, 1 at % Eu) to 16.3 nm (10 at % Eu). According to electron microscopy data, the size of nanoparticles is 1–2 nm larger than the CSR value, which indicates the presence of an amorphous shell in the synthesis product particles. The product nanoparticles are organized into spherical agglomerates (from 0 to 5 at % Eu), while in the case of TiO₂–10 at % Eu, no hierarchically organized structures were found. When applying a TiO₂ film by microextrusion printing using the powder obtained in the manufacture of functional inks, the microstructure and crystal structure of the powder used are preserved.

The process of preparation of vanadyl butoxyacetylacetate was studied, which was then used as a precursor in the synthesis of vanadium oxide by the sol-gel process using solvothermal treatment. After solvothermal treatment of the dispersed system obtained as a result of hydrolysis, vanadium dioxide powder in the monoclinic polymorphic modification VO₂(B) was obtained. In terms of microstructure, the powder consists of agglomerates with a likely large amorphous component, and the average size of coherent scattering regions was 9 ± 3 nm. The resulting powder was used to prepare functional inks, which were applied to deposit a vanadium oxide film by microextrusion printing. After heat treatment in air at 450°C, the formed film of V₂O₅ exhibited anodic electrochromism, changing color to pale blue upon reduction and to a less transparent yellow-orange upon oxidation. The optical contrast reached 16% at a wavelength of 500 nm, and the film’s coloration efficiency was 53.4 cm²/C. Compared to films obtained using this precursor by dip coating or spin coating methods, the same coloration and bleaching times are observed, as well as increased stability of the optical contrast value during cycling.

A vanadium pentoxide film was obtained via dip-coating using vanadyl alkoxoacetylacetonate as a precursor. The material crystallizes in the tetragonal β-V₂O₅ modification and exhibits pronounced (200) texturing. It consists of one-dimensional structures with an aspect ratio of at least 10, some of which are consolidated into agglomerates where the particles are in contact along their long facets. According to Raman spectroscopy and the measured work function (4.63 eV) obtained by Kelvin probe force microscopy (KPFM), the oxide contains a noticeable amount of V⁴⁺ species. In terms of electrochromic behavior, the material exhibits anodic electrochromism, changing color to pale blue upon reduction and to a less transparent yellow-orange upon oxidation. The optical contrast reaches up to 27% in the blue region of the visible spectrum. These findings suggest that β-V₂O₅ materials synthesized using vanadyl alkoxoacetylacetonate are promising candidates for application in electrochromic devices.

Using vanadyl and nickel alkoxoacetylacetonates, films of vanadium pentoxide doped with 1, 3, and 10 mol % nickel oxide were obtained. All films crystallize in the tetragonal β-V₂O₅ modification. The materials are highly textured along axis (200) and consist of one-dimensional structures. However, at 3 and 10 mol % NiO, nanoparticles with sizes of 30–50 nm are also observed in addition to the one-dimensional structures. According to Raman spectroscopy data, the materials contain a significant amount of V⁴⁺ ions, but no traces of NiO phases were detected. From the standpoint of electrochromic properties, all obtained materials are cathodic, changing color to dark blue upon reduction and to a more transparent yellow upon oxidation. An increase in nickel content leads to a decrease in coloration efficiency and a slowdown of electrochromic processes. The results of the study indicate the potential of using nickel-doped V₂O₅-based materials obtained with metal alkoxoacetylacetonates as precursors for components in electrochromic devices.

Microstructural features, phase composition, and eletrochromic properties of V₂O₅ film formed by spin-coating using vanadyl alkoxoacetylacetonate as a precursor have been studied. The obtained material possesses a significant amount of V⁴⁺ ions, which is indicated both by the presence of the corresponding modes in the Raman spectra and the presence of the V₇O₁₆ phase. As a result, the material exhibits anodic electrochromism; it colors upon oxidation, changing color from pale blue to a much less transparent orange-yellow. The optical contrast can reach 30% at a wavelength of 400 nm, and the coloration efficiency is 65.26 cm²/C. The results of the study clearly demonstrate the promising application of materials based on V₂O₅, obtained using heteroligand hydrolytically active vanadyl complexes, as functional components of devices that provide a change in optical properties when an electrical voltage is applied.

This study presents the fabrication possibilities of ultra-high-temperature ceramics of ZrB₂-30 vol.%SiC and (ZrB₂-HfB₂)-30 vol.% SiC composition using the reaction spark plasma sintering of composite powders ZrB₂(HfB₂)-(SiO₂-C) under two-stage heating conditions. The phase composition and microstructure of the obtained ceramic materials have been subjected to detailed analysis, their electrical conductivity has been evaluated using the four-contact method, and the electron work function has been determined using Kelvin probe force microscopy. The thermal analysis in the air, as well as the calcination of the samples at temperatures of 800, 1000, and 1200 °C in the air, demonstrated a comparable behavior of the materials in general. However, based on the XRD data and mapping of the distribution of elements on the oxidized surface (EDX), a slightly higher oxidation resistance of the ceramics (ZrB₂-HfB₂)-30 vol.% SiC was observed. The I-V curves of the sample surfaces recorded with atomic force microscopy demonstrated that following oxidation in the air at 1200 °C, the surfaces of the materials exhibited a marked reduction in current conductivity due to the formation of a dielectric layer. However, data obtained from Kelvin probe force microscopy indicated that (ZrB₂-HfB₂)-30 vol.% SiC ceramics also demonstrated enhanced resistance to oxidation.

Crystal structure, morphology, and electrochromic properties of V₂O₅ film prepared using vanadyl alkoxoacetylacetonate as precursor have been studied. We have shown that the obtained vanadium pentoxide contains significant amount of V⁴⁺ cations, which is indicated by low electron work function. This results in material possessing anodic electrochromism (coloring upon oxidation) with rapid bleaching process (1 s upon the corresponding potential application). Anodic coloration is observed in the whole visible light spectrum, as well as in near IR region up to 1100 nm. The obtained data show high prospects for approach to formation of V₂O₅-based films using vanadyl acetylacetonate as precursor and application of these films as components of smart windows and displays, optical properties of which could be controlled by electrical current application.

Polymer nanocomposites filled with carbon nanoparticles (CNPs) are a hot topic in materials science. This article discusses the current research on the use of these materials as interfacial electron transfer films for solid contact potentiometric membrane sensors (SC-PMSs). The results of a comparative study of plasticized poly (vinyl chloride) (pPVC) matrices modified with single-walled carbon nanotubes (SWCNTs), fullerenes-C60, and their hybrid ensemble (SWCNTs-C60) are reported. The morphological characteristics and electrical conductivity of the prepared nanostructured composite films are reported. It was found that the specific electrical conductivity of the pPVC/SWCNTs-C60 polymer film was higher than that of pPVC filled with individual nanocomponents. The effectiveness of this composite material as an electron transfer film in a new potentiometric membrane sensor for detecting phenylpyruvic acid (in anionic form) was demonstrated. Screening for this metabolic product of phenylalanine in body fluids is of significant diagnostic interest in phenylketonuria (dementia), viral hepatitis, and alcoholism. The developed sensor showed a stable and fast Nernstian response for phenylpyruvate ions in aqueous solutions over the wide linear concentration range of 5 × 10⁻⁷–1 × 10⁻³ M, with a detection limit of 10^−7.2 M.

The development of scientific and technological foundations for the creation of high-performance energy storage devices is becoming increasingly important due to the rapid development of microelectronics, including flexible and wearable microelectronics. Supercapacitors are indispensable devices for the power supply of systems requiring high power, high charging-discharging rates, cyclic stability, and long service life and a wide range of operating temperatures (from −40 to 70 °C). The use of printing technologies gives an opportunity to move the production of such devices to a new level due to the possibility of the automated formation of micro-supercapacitors (including flexible, stretchable, wearable) with the required type of geometric implementation, to reduce time and labour costs for their creation, and to expand the prospects of their commercialization and widespread use. Within the framework of this review, we have focused on the consideration of the key commonly used supercapacitor electrode materials and highlighted examples of their successful printing in the process of assembling miniature energy storage devices.

The goal of this work was the synthesis study of the [WO₂(C₅H₇O₂)₂] complex and its application as a precursor for the growth of WO₃ films in hydrothermal conditions, as well as evaluating the microstructural features and electrochromic properties of the formed materials. Dioxotungsten acetylacetonate was synthesized in an aqueous medium and purified. It was found that during hydrothermal treatment of the alcohol solution of the complex, acetylacetonate ligands undergo partial destructive substitution by alkoxyl groups, intensifying at temperatures above 140 °C. Considering these data and using a [WO₂(C₅H₇O₂)₂] solution, WO₃ films were grown on glass and glass/ITO substrates. The resulting films had different microstructures according to scanning electron microscopy (SEM) and atomic force microscopy (AFM): the former consisted of submicron spheres (~500 nm), distinct nanoparticles (60–160 nm), and submicron- and micron-sized ridges, while the latter consisted of 1D structures (length 350 ± 25 nm, width 110 ± 25 nm). Using Kelvin probe force microscopy (KPFM), the electron work function was determined for the film on glass/ITO substrate (4.77 eV). It was found that the electrochemical coloration process of the obtained WO₃ film can proceed in two stages, and the optical contrast is about 17.5% (at the wavelengths of 600–1100 nm). The results obtained show the prospects of applying the proposed approach to obtaining WO₃ electrochromic films with a hierarchical microstructure with the hydrothermal method using the [WO₂(C₅H₇O₂)₂] complex as a precursor.