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Polyurethane-based thin-film composites (PUR-based TFCs) with different carbon fillers, namely, carbon flocs formed by carbon dots (CDs) containing O, N, and F heteroatoms and carbon nanotubes (CNTs), were prepared by hot pressing. The morphology and composition of the carbon fillers were investigated by SEM/EDX. Temperature-programmed desorption mass spectrometry and thermogravimetric analysis revealed that the CNTs have the highest thermostability among the fillers. Microwave studies in the X-band showed that the PUR-based TFCs with the CNTs were characterized by higher reflection losses and lower transmission losses than the PUR-based TFCs with the flocs formed by the studied CDs. [ABSTRACT FROM AUTHOR]

Carbon nanoparticles (CNPs) emitting pH-dependent blue photoluminescence (PL) in aqueous solutions were solvothermally prepared and modified with a new fluorophore molecule, N-chlorobenzyl dithiomaleimide dimethyl diacetate (NCBDTM), with pH-dependent yellow-green PL in aqueous solutions and irreversible PL emission quenching in alkaline aqueous solutions at basic pHs. In the π-complex system formed by donor CNPs and acceptor NCBDTM molecules, energy transfer occurs by the FRET mechanism. Due to the implementation of the FRET mechanism, a significant Stokes shift of 170 nm is observed, making this and similar systems promising for the visualization of pH-dependent processes in the green-yellow visible light region. [ABSTRACT FROM AUTHOR]

Adsorption is currently the most promising capture technology to shorten atmospheric emissions of carbon dioxide (CO2). In this article, we report on the adsorption of CO2 onto pristine, oxidized, and aminated activated carbon (AC) sorbents. From our findings, some functionalized AC sorbents have shown very promising results in the CO2 capture process. Their maximum adsorption capacity measured by the thermogravimetric method at 20 °C varies between 2.2 and 3.9 mmol CO2/g depending on the content of diethylamino and oxygen-containing groups. The functionalization of the carbon surface with diethylamino groups improves the adsorption capacity by 30–40%. The CO2 adsorption little depends on the texture parameters of the pristine AC sorbents. In the range from 20 to 100 °C, the CO2 thermodesorption showed the effective regeneration of the sorbents. The aminated carbon surface demonstrates the best CO2 adsorption but binds the adsorbed molecules stronger than the oxidized surface, which limits the sorbent regeneration.

In this study, we considered changes in the surface chemistry after introducing fluorine into the surface layer of nanoporous activated carbon (BAU) produced from the birch wood. Here, we examined the BAU treated with 1,1,1,2-tetrafluoroethane at the selected temperature in the range of 400–800 °C. Diverse methods, including chemical analysis, nitrogen adsorption–desorption, SEM–EDS, XPS, and 19F solid-state NMR, were used for the characterization of the prepared materials. It was found that one can introduce from 0.17 to 0.42 mmol of F per gram of BAU using fluoroalkylation at 400–500 °C. Increasing the temperature to 600 °C increases the fluorination efficiency, and the relatively high fluorine content of 1.86 mmol of F per gram of BAU can be reached. At least three group types, namely, C–F, CF2, and CF3 groups, were found by XPS and 19F solid-state NMR after such treatment. The content of "semi-ionic" fluorine drastically increases in the surface layer after high-temperature fluoroalkylation at 700 °C and 800 °C. This "semi-ionic" fluorine, in the form of C–F and CF2 groups, is directly conjugated with the π-electron system of the carbon matrix. [ABSTRACT FROM AUTHOR]

Here we disclosed the substantial effect of the local medium in the vicinity of the excited Nd3+ions on the optical properties and the laser characteristics of glasses. The UV-Vis absorption of the laser BaO/SrO–P2O5–Al2O3–K2O–B2O3–La2O3glasses doped with Nd3+ions is measured at 25 °C. Judd-Ofelt (JO) theoretical analysis of 4f electron transitions in the Nd3+absorption spectra was performed. From the JO intensity parameters, a set of the laser4F3/2→4I11/2transitions characteristics are found and stimulated emission cross-sections are characterized. The effect of different Ba/Sr ratio on the structure-properties relationships in the glasses is shown. [ABSTRACT FROM AUTHOR]

According to the proposed pyrolytic method, granular activated carbon (AC) Norit 830 W was functionalized by thermal treatment of AC in hydrofluorocarbon (HFC) gases, pentafluoroethane and 1,1,1,2-tetrafluoroethane, at 400-800 °C. This method does not require activation by plasma and photons. Chemical and elemental analysis showed that the pyrolytic treatment provides a loading of 2.95 mmol (5.6 wt%) of fluorine per gram of AC. Nitrogen adsorption measurements indicated that the microporous structure contracted when AC was treated with HFC at temperatures above 400 °C. Thermogravimetry, Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR), and X-ray photoelectron spectroscopy (XPS) demonstrated the evolution of oxygen-containing and fluorine-containing groups to more thermostable groups with treatment temperature. The fluorine-containing groups grafted at high temperature, above 600 °C exhibited the highest thermal stability up to 1250 °C in dry argon. From the data of XPS and solid-state 19 F nuclear magnetic resonance spectroscopy data, the grafted fluorine exists in several types of grafted F-containing groups, the HFC residues. By changing the thermal regime of fluorination, the composition of fluorine-containing groups on a carbon surface can be regulated. Isolated fluoroalkyl groups can be grafted at temperatures of 400-500 °C, while at 600 °C and above, the semi-ionic fluorine groups increase significantly. The hydrophobized surface demonstrated the ability to effectively decompose H 2 O 2 in methanol solutions., Competing Interests: There are no conflicts to declare. A. Zaderko is listed as the Fluocar® trademark owner of the US 5,479,088 and Ukraine 213,198 registration., (This journal is © The Royal Society of Chemistry.)