Arman Umirzakov

Lithium-ion battery (LIB) recycling is usually compared across pyrometallurgical, hydrometallurgical and direct routes as if the optimal route were independent of the cathode being recycled. This review argues that cathode chemistry is the governing variable. Following the chain from cathode chemistry and degradation mechanism through pretreatment, recycling route and recovered product to electrochemical validation, we compare LiNi_xMn_yCo_zO₂ (NMC, 111 to 811) and LiFePO₄ (LFP), with LiCoO₂ and LiNi_0.8Co_0.15Al_0.05O₂ as references. LFP degradation is dominated by Li loss and Fe/Li anti-site defects in an intact olivine framework, which makes direct regeneration mechanistically well founded. Ni-rich NMC suffers microcracking, surface reconstruction and proton sensitivity, so its regeneration increasingly becomes upcycling into a different product, whereas hydrometallurgical resynthesis currently has the strongest industrial validation. Reported recovery efficiencies above 95% rarely demonstrate battery-grade products, and published energy estimates for the same route and chemistry differ by a factor of up to about 1.5 because of inconsistent system boundaries. We propose a cathode-to-cathode circularity framework and a minimum reporting set that link material recovery to validation in new cells.

This paper reports an assessment of the photocatalytic activity of TiO₂ nanotubes (TNTs) doped with strontium titanate (SrTiO₃) and sulfur (S) with respect to the decomposition of methylene blue (MB). TNT was obtained by the double anodizing method with further doping of strontium titanate by the hydrothermal method and additional annealing in an atmosphere of N₂ (95%) + H₂S (5%) at 450–550 °C. The photocatalytic activity was evaluated using MB as a pollutant and this study was conducted using an Osram Vita-Lux lamp with a power of 300W as a visible light source. The photocatalytic abilities of the synthesized materials were investigated, and characterized by methods such as SEM, TEM, XRD, EDS, and UV–Vis spectroscopy. Our study showed that the SrTiO₃/TiO₂NT@S composite has a better photocatalytic decomposition ability for the dye under consideration compared to pure TNT and SrTiO₃/TiO₂NT. These results clearly demonstrate the potential of synthesized SrTiO₃/TiO₂NT@S material for applications in water purification and photocatalysis.

Antimony oxychloride compounds represent a distinct class of inorganic materials that combine structural features characteristic of both oxides and halides. Their compositional flexibility and anisotropic properties make them promising candidates for use in photocatalytic systems, optoelectronic devices, flame-retardant coatings, and energy storage technologies. This review provides an overview of the structural characteristics and synthesis strategies associated with key members of the Sb_xO_yCl_z family, including SbOCl, Sb₄O₅Cl₂, and Sb₈O₁₁Cl₂. Emphasis is placed on how synthesis parameters—such as temperature, pH, and precursor composition—govern phase formation, morphology, and resulting properties. Recent advances in composite engineering, controlled doping, and surface modification are discussed as effective routes to overcome limitations such as low conductivity and chemical instability. The broader significance of antimony as a strategic element is also addressed in the context of global resource availability and its role in sustainable technologies. Overall, these materials provide a versatile platform for the design of multifunctional systems tailored to meet future demands in materials science and applied engineering.

In this paper hybrid nanostructures of molybdenum disulfide (MoS₂) and nickel-modified MoS₂ (Ni/MoS₂) were synthesized in two different ways, that is, by chemical gas phase deposition and magnetron scattering, and their structural and morphological properties were thoroughly studied. Scanning electron microscopy was analyzed to assess the surface morphology and microstructure of the synthesized samples, energy-dispersion X-ray spectroscopy to determine the elemental composition, and phase correspondence with the crystal structure was analyzed using Raman spectroscopy. Scanning electron microscopy analysis revealed the formation of hexagonal symmetric high-crystalline triangular crystals characteristic of layered materials. Elemental mapping confirmed the distribution of molybdenum and sulfur, and the uniform distribution of the nickel layer in the heterostructure. While the Raman spectra show characteristic oscillation modes E _2g ~380 cm ^-1 and A _1g ~406 cm ^-1 with a distance Δ ≈ 25.8 cm ^-1 indicating the formation of the MoS ₂ layer, the indicators of two phases of MoS ₂ in heterostructure were evidence. These results make it possible to optimize the synthesis conditions by controlling the structure, properties and phase composition of the resulting materials. This, in turn, will expand the possibility of using materials in the future in sensor systems, optoelectronic devices, hydrogen evolution reaction and other catalytic processes. In addition, the NI modification improves the functional characteristics of MoS₂ materials and increases their potential in multidisciplinary application areas.

In this paper, the problem of synthesis of a hybrid nanostructure based on WS₂@MXene and a comprehensive study of its structural properties is considered. The WS₂@MXene material was obtained using a two-stage method. First, the Ti₃AlC₂ MAX phase was treated with hydrofluoric acid to obtain Ti₃C₂ MXene layered material, then WS₂ nanostructures were synthesized by hydrothermal method and the two components were combined by ultrasonic mixing. The samples obtained as a result of the synthesis were studied using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. X-ray diffraction data confirmed an increase in the hexagonal structure of the WS₂ phase and the MXene interlayer space. The morphology images clearly showed the WS₂ petals embedded in MXene leaflets, and the results of the chemical bond study clarified the necessary elemental composition of the hybrid. The synthesized material has a hierarchical structure consisting of complex nanotubes and nanowires. This structure provides a high specific surface area, efficient electron transfer, and an increase in the number of active catalytic media. The WS₂@MXene hybrid is a promising material for energy storage systems, hydrogen evolution reactions, and gas detection sensors.

In this study, a new hybrid hydrogel based on PAM (polyacrylamide)-Ag-g/WS₂/Ti₃C₂T_x was synthesized by radical polymerization using a conductive heterostructural nanocomposite WS₂/Ti₃C₂T_x. The synergy between the polymer matrix and the interface between two-dimensional nanomaterials ensured the production of a hydrogel with high extensibility and conductivity, as well as sensory characteristics. The composite hydrogel exhibited excellent strain-sensing capabilities, with gauge factors of 1.4 at low strain and 2.8 at higher strain levels. In addition, the material showed a fast response time of 2.17 s and a short recovery time of 0.46 s under cyclic stretching, which confirms its high reliability and reproducibility. The integration of Ti₃C₂T_x and WS₂ promoted the formation of a conductive network in the hydrogel structure, which simultaneously increased its mechanical strength and signal stability under variable loads. Measurements confirm some potential of the PAM-Ag-g/WS₂/Ti₃C₂T_x composite hydrogel as a flexible wearable strain sensor. Based on measured numbers, we discussed the impact of the WS₂/Ti₃C₂T_x interface on the Gauge factor and conductivity of the composite. Theoretical modeling demonstrates significant changes in the electronic structure of the WS₂/Ti₃C₂T_x interface, and especially the WS₂ surface, induced by substrate strain. Possible applications of the peculiar properties of PAM-Ag-g/WS₂/Ti₃C₂T_x composite were proposed.

This paper presents a study of the structural characteristics of a promising MoS2-based material obtained by chemical vapor deposition (CVD). Optimization of the synthesis process to obtain the desired structure is also presented. The optimal parameter for the synthesis of CVD MoS2 crystals was found to be the maximum sulfurization temperature of 780 °C with an exposure time of about 15 minutes, the heating temperature of the sulfur source zone of 250 °C, the distance between the sulfur and molybdenum sources of 25 cm, and the distance between the molybdenum source and the substrate was 1.5 cm. The morphology and elemental composition of the obtained samples were studied using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). Using SEM, it was revealed that MoS2 crystals are formed in a triangular shape and are evenly distributed over the surface of the substrate. The maximum sizes of crystallites reach 6 microns. EMF mapping of crystallites confirmed the homogeneous distribution of molybdenum and sulfur in the structure, revealing only minor variations in composition at the grain boundaries. The quality and quantity of the sample layer were studied using Raman spectroscopy. The results showed two characteristic peaks (vibrational modes E2g1 and A1g) of nanoscale MoS2. The peaks have a sharp shape and are located at a distance of ≈20.9 cm-1, which may indicate the high quality of the crystal structure of the obtained crystallites. The results obtained emphasize the effectiveness of the chosen approach and the importance of the work for the development of 2D materials technologies.

Layers of TiO₂ nanotubes formed through an anodization process are an area of active research in the context of innovative energy conversion and storage systems. Titanium nanotubes (TNT) have attracted attention due to their unique properties, especially their high surface-to-volume ratio, making them a desirable material for various technological applications. The anodizing method is widely used for the production of TNT due to its simplicity and relative cheapness, the method allows precise control of the thickness of TiO₂ nanotubes. Anodizing can also be used to create decorative and colored coatings on titanium nanotubes. In this study, a combined structure comprising anodic TiO₂ nanotubes and SrTiO₃ particles was created using chemical synthesis methods. TiO₂ nanotubes were prepared by anodizing in ethylene glycol containing NH₄F and Н₂O using a voltage of 30 volts.The anodic nanotube array, heat-treated at 450°C, was then placed in an autoclave filled with a dilute SrTiO₃ solution. Scanning electron microscopy (SEM) analysis revealed that TNT are characterized by clear and open tube ends. With an average outer diameter of 1 µm and an inner diameter of 69 nm, and their length is 133 nm.

Layers of TiO₂ nanotubes formed by the anodization process represent an area of active research in the context of innovative energy conversion and storage systems. Titanium nanotubes (TNTs) have attracted attention because of their unique properties, especially their high surface-to-volume ratio, which makes them a desirable material for various technological applications. The anodization method is widely used to produce TNTs because of its simplicity and relative cheapness; the method enables precise control over the thickness of TiO₂ nanotubes. Anodization can also be used to create decorative and colored coatings on titanium nanotubes. In this study, a combined structure including anodic TiO₂ nanotubes and SrTiO₃ particles was fabricated using chemical synthesis techniques. TiO₂ nanotubes were prepared by anodizing them in ethylene glycol containing NH₄F and H₂O while applying a voltage of 30 volts. An anode nanotube array heat-treated at 450 °C was then placed in an autoclave filled with dilute SrTiO₃ solution. Scanning electron microscopy (SEM) analysis showed that the TNTs were characterized by clear and open tube ends, with an average outer diameter of 1.01 μm and an inner diameter of 69 nm, and their length is 133 nm. The results confirm the successful formation of a structure that can be potentially applied in a variety of applications, including hydrogen production by the photocatalytic decomposition of water under sunlight.