In this work, we report the synthesis of perovskite-type Ba-doped LaFeO₃ (La_1−xBa_xFeO₃, x = 0.00, 0.02, 0.04, and 0.06) nanofibers (NFs) using the electrospinning method. The synthesized La_1−xBa_xFeO₃ materials have a fibrous structure with an average fiber diameter of 250 nm. The fibers, in turn, consist of smaller crystalline particles of 20–50 nm in size. The sensor properties of La_1−xBa_xFeO₃ nanofibers were studied when detecting 20 ppm CO, CH₄, methanol, and acetone in dry air in the temperature range of 50–350 °C. Doping with barium leads to a significant increase in sensor response and a decrease in operating temperature when detecting volatile organic compounds (VOCs). The process of acetone oxidation on the surface of the most sensitive La_0.98Ba_0.02FeO₃ material was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed desorption in combination with mass spectrometry (TPD-MS). A mechanism for the sensor signal formation is proposed.

Unique properties possessed by transition metal dichalcogenides (TMDs) attract much attention in terms of investigation of their formation and dependence of their characteristics on the production process parameters. Here, we investigate the formation of TMD films during chemical vapor deposition (CVD) in a mixture of thermally activated gaseous H₂S and vaporized transition metals. Our observations of changes in morphology, Raman spectra, and photoluminescence (PL) properties in combination with in situ measurements of the electrical conductivity of the deposits formed at various precursor concentrations and CVD durations are evidence of existence of particular stages in the TMD material formation. Gradual transformation of PL spectra from trion to exciton type is detected for different stages of the material formation. The obtained results and proposed methods provide tailoring of TMD film characteristics necessary for particular applications like photodetectors, photocatalysts, and gas sensors.

A composite based on θ-Al₂O₃ microspheres coated with graphene oxide (GO) and reduced graphene oxide (RGO) was prepared and evaluated as a sorbent for the removal of synthetic dyes from aqueous solutions. GO was synthesized by a modified Hummers’ method and deposited onto alumina microspheres via ultrasound-assisted treatment under various conditions, followed by supercritical reduction to obtain the Al₂O₃_RGO composite. The structure, morphology, and composition of the materials were characterized by Raman spectroscopy, SEM, TGA/DSC, FTIR, and XRD, revealing the formation of mono- and few-layer GO/RGO coatings on the substrate surface. Adsorption tests for cationic methylene blue (MB) dye and anionic methyl orange (MO) dye demonstrated that the alumina substrate was inactive, whereas GO- and RGO-coated microspheres exhibited high adsorption efficiency for MB and partial uptake of MO from water solutions. In mixed-dye solutions, both Al₂O₃_GO and Al₂O₃_RGO composites showed selectivity toward MB, and the RGO-based composite demonstrated enhanced MB adsorption at low concentrations. The results highlight GO/RGO-coated θ-Al₂O₃ microspheres as convenient and selective composite sorbents for water purification processes.

In this work we report the synthesis and characterization of WS2/MoS2 heterostructures prepared by sequential chemical vapor deposition (CVD) using H2S and thermally evaporated metal as precursors. A thin WS2 covers (1–2 monolayers) are produced on pre-formed MoS2 nanowall films, resulting in nearly complete quenching of the MoS2 photoluminescence (PL) and emergence of a dominant WS2 PL peak at higher energy. Remarkably, electrical measurements reveal that the thermally activated conduction in the both layered materials have nearly the same activation energies, suggesting comparable donor activation energies and a possible near-alignment of the CBM positions within experimental uncertainty. This particular “quasi-type-I” alignment is in sharp contrast to the conventional staggered (type-II) alignment normally expected in WS2/MoS2 heterostructures. Transient absorption pump-probe spectroscopy shows signatures consistent with ultrafast interlayer charge transfer and possible interlayer exciton formation. We present a comprehensive study of the optical, structural, and transport properties of prepared samples, and discuss the carrier transfer mechanisms that give rise to the observed PL redistribution.

Two series of nanocomposites based on SnO₂ and WO₃ were synthesized by the same route—chemical precipitation of corresponding acids with subsequent thermal decomposition followed by modification with MnO_x via impregnation-annealing technique. Comparative study of phase composition by X-ray diffraction and Raman spectroscopy was carried out. Microstructural parameters (particle size, specific surface area) were determined using electron microscopy and low-temperature N₂ adsorption. Gas sensing properties of the nanocomposites were investigated when detecting inorganic (CO, NO, NH₃) and organic (CH₃OH, C₆H₆) gases.