Dynamics of photogenerated charge carriers in TiO2 /MoO3, TiO2 /WO3 and TiO2 /V2O5 photocatalysts with mosaic structure

Titania is a widely used photocatalytic material possessing such advantages as low cost and high reactivity under the ultraviolet light illumination. However, the fast recombination of photoexcited charge carriers limits its application. Herein, we have synthesized original nanomaterials with mosaic structures that exhibited well-defined heterojunctions and new properties. Using SEM, XRD, EPR spectroscopy, photocatalytic measurements, and photoinduced pathphysiological activity of these photocatalysts, we studied the processes of charge carrier accumulation in TiO2 /MoO3, TiO2 /WO3, and TiO2 /V2 O5 under in situ UV illumination with emphasis on the charge exchange between energy levels of these nanosized semiconductors. It is shown that the accumulation of photoinduced charges occurs in two forms (i) filled electron traps corresponding to Ti4+ /Ti3+ levels and (ii) Mo5+ centers, both forms contributing to the photoinduced biocide activity of the samples. This work demonstrates that light exposure of heterostructure photocatalysts with mosaic surfaces produces different types of charge-trapping centers capable of interacting with molecular oxygen yielding peroxo species, which provide long-life light-induced ”self-cleaning” behavior. Such photoaccumulating materials open new opportunities in developing light-driven self-sterilization structures exhibiting a prolonged bactericidal effect up to 10 h after stopping light exposure. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

The Effect of Sibunit Carbon Surface Modification with Diazonium Tosylate Salts of Pd and Pd-Au Catalysts on Furfural Hydrogenation

Funding Information: The research is funded by the Ministry of Education and Science of the Russian Federation Program № 075-03-2021-287/6. Sevastopol State University Research grant 42-01-09/169/2021-4 (Russia). Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Herein, we investigated the effect of the support modification (Sibunit carbon) with diazonium salts of Pd and Pd-Au catalysts on furfural hydrogenation under 5 bars of H2 and 50 °C. To this end, the surface of Sibunit (Cp) was modified with butyl (Cp-Butyl), carboxyl (Cp-COOH) and amino groups (Cp-NH2) using corresponding diazonium salts. The catalysts were synthesized by the sol immobilization method. The catalysts as well as the corresponding supports were characterized by Fourier transform infrared spectroscopy, N2 adsorption-desorption, inductively coupled plasma atomic emission spectroscopy, high resolution transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Hammet indicator method and X-ray photoelectron spectroscopy. The analysis of the results allowed us to determine the crucial influence of surface chemistry on the catalytic behavior of the studied catalysts, especially regarding selectivity. At the same time, the structural, textural, electronic and acid–base properties of the catalysts were practically unaffected. Thus, it can be assumed that the modification of Sibunit with various functional groups leads to changes in the hydrophobic/hydrophilic and/or electrostatic properties of the surface, which influenced the selectivity of the process.publishersversionpublishe

Pulsed Vacuum Arc Deposition of Nitrogen-Doped Diamond-like Coatings for Long-Term Hydrophilicity of Electrospun Poly(ε-caprolactone) Scaffolds

The surface hydrophobicity of poly(ε-caprolactone) electrospun scaffolds prevents their interactions with cells and tissue integration. Although plasma treatment of scaffolds enhances their hydrophilicity, this effect is temporary, and the hydrophobicity of the scaffolds is restored in about 30 days. In this communication, we report a method for hydrophilization of poly(ε-caprolactone) electrospun scaffolds for more than 6 months. To that end, diamond-like coating was deposited on the surface of the scaffolds in a nitrogen atmosphere using pulsed vacuum arc deposition with sputtering of graphite target. This approach allows for a single-side hydrophilization of the scaffold (water contact angle of 22 ± 3° vs. 126 ± 2° for pristine PCL scaffold) and preserves its structure. With increased nitrogen pressure in the chamber, sp3-hybridized carbon content decreased twice (sp2/sp3 ratio decreased from 1.06 to 0.52), which demonstrates the possibility of tailoring the content of carbon in sp2 and sp3 hybridization state. Nitrogen content in the deposited coatings was found at 16.1 ± 0.9 at.%. In vitro tests with fibroblast cell culture did not reveal any cytotoxic compounds in sample extracts

Data on nitridation effect of AlTiTaZrHf(-N) high entropy films by X-ray photoelectron spectroscopy

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Aryne cycloaddition reaction as a facile and mild modification method for design of electrode materials for high-performance symmetric supercapacitor

International audienceCovalent modification of graphene-based materials can be considered as one of the most promising methods for tailoring their electrochemical properties and extending their application as electrode materials for supercapacitors. In this contribution, we report a facile and mild approach for the covalent functionalization of reduced graphene oxide (rGO) via aryne cycloaddition using pseudocyclic iodoxoborole as an aryne source. The structure and chemical composition of the functionalized rGO (f-rGO) were assessed by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), ultraviolet-visible (UV-vis) spectrophotometry, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), which revealed the negligible influence of covalent modification on the rGO structure. Transmission electron microscopy (TEM) imaging showed an increase of the interlayer distance from 0.38 to 0.46 nm upon functionalization. The electrochemical performance of f-rGO material was studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques in 2 M KOH aqueous solution as the electrolyte. Under optimized conditions, the f-rGO displayed a high specific capacitance of 297 F g-1 at a current density of 1 A g-1, which is much higher than that of unmodified rGO (170 F g-1 at 1 A g-1). Therefore, the f-rGO was used to construct a symmetric supercapacitor device, exhibiting an energy density of 6.7 Wh kg-1 at a power density of 685.8 W kg-1. The device exhibited good cycling stability and ability to maintain about 96% of the initial capacitance value after 10,000 cycles. Furthermore, two symmetric supercapacitor devices were successfully applied to power a home-designed windmill device for 3 s. The results obtained in the present study highlight the importance of graphene functionalization as an effective route to fabricate rGO-based materials with enhanced properties in energy storage devices

Effect of nitrogen content on structural and mechanical properties of AlTiZrTaHf(-N) high entropy films deposited by reactive magnetron sputtering

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Bioprinting of functional vascularized mouse thyroid gland construct.

Bioprinting can be defined as additive biofabrication of 3D tissues and organ constructs using tissue spheroids, capable of self-assembly, as building blocks. Thyroid gland, a relatively simple endocrine organ, is suitable for testing the proposed bioprinting technology. Here we report the bioprinting of functional vascularized mouse thyroid gland construct from embryonic tissue spheroids as a proof of concept. Based on the self-assembly principle, we generated thyroid tissue starting from thyroid spheroids (TS) and allantoic spheroids (AS), as a source of thyrocytes and endothelial cells (EC), respectively. Inspired by mathematical modelling of spheroid fusion, we used an original 3D bioprinter to print TS in close association with AS within collagen hydrogel. During the culture, closely placed embryonic tissue spheroids fused into a single integral construct, endothelial cells from AS invaded and vascularized TS, and epithelial cells from the TS progressively formed follicles. In this experimental setting, we observed formation of capillary network around follicular cells, as observed during in utero thyroid development when thyroid epithelium controls the recruitment, invasion and expansion of EC around follicles. To prove that EC from AS are responsible for vascularization of thyroid gland construct, we depleted endogenous EC from thyroid spheroids before bioprinting. EC from allantoic spheroids completely revascularized depleted thyroid tissue. Cultured bioprinted construct was functional as it could normalize blood thyroxin levels and body temperature after grafting under the kidney capsule of hypothyroid mice. Bioprinting of functional vascularized mouse thyroid gland construct represents further advance in bioprinting technology exploring self-assembling properties of tissue spheroids