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Visible light thiocyanation of <i>N</i> -bearing aromatic and heteroaromatic compounds using Ag/TiO <sub/>2</sub> nanotube photocatalyst
摘要： In this study, Ag/TiO2 nanotubes (Ag/TNT) were synthesized via simple hydrothermal process, and this photocatalyst was successfully exploited in thiocyanation reactions at room temperature under visible light irradiation. Four classes of important heterocyclic compounds including indole, aniline, pyrrole and 2-amino thiazole derivatives via Ag/TNT treated with ammonium thiocyanate formed the corresponding thiocyano compounds in moderate to excellent yields. Plasmonic property and catalytic performance of Ag nanoparticles (which mainly deposited on the surface of TNT) in absorbing species containing sulfur atoms were key components for the reactions to proceed. This potent, simple and versatile protocol reported for the first time afforded thiocyanation reactions of aniline, pyrrole and 2-amino thiazole derivatives under visible light. The reactions proceeded through a radical pathway by applying air molecular oxygen as a low-cost and environmentally friendly terminal oxidant.
关键词： thiocyanation,photocatalyst,visible light,heterocyclic compounds,Ag/TiO2 nanotubes
更新于2025-09-04 15:30:14
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Ta <sub/>3</sub> N <sub/>5</sub> /Co(OH) <sub/>x</sub> composites as photocatalysts for photoelectrochemical water splitting
摘要： Ta3N5 nanotubes (NTs) were obtained from nitridation of Ta2O5 NTs, which were grown directly on Ta foil through a 2-step anodization procedure. With Co(OH)x decoration, a photocurrent density as high as 2.3 mA cm?2 (1.23 V vs. NHE) was reached under AM1.5G simulated solar light; however, the electrode suffered from photocorrosion. More stable photoelectrochemical (PEC) performance was achieved by first loading Co(OH)x, followed by loading cobalt phosphate (Co–Pi) as double co-catalysts. The Co(OH)x/Co–Pi double co-catalysts may act as a hole storage layer that slows down the photocorrosion caused by the accumulated holes on the surface of the electrode. A “waggling” appearance close to the “mouth” of Ta2O5 NTs was observed, and may indicate structural instability of the “mouth” region, which breaks into segments after nitridation and forms a top layer of broken Ta3N5 NTs. A unique mesoporous structure of the walls of the Ta3N5 NTs, which is reported here the first time, is also a result of the nitridation process. We believe that the mesoporous structure makes it difficult for the nanotubes to be fully covered by the co-catalyst layer, hence rationalizing the remaining degradation by photocorrosion.
关键词： photoelectrochemical water splitting,photocorrosion,Co–Pi,Co(OH)x,mesoporous structure,Ta3N5 nanotubes
更新于2025-09-04 15:30:14
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Thermal and electrical conductivity enhancement of solar glycol-water mixture containing MWCNTs
摘要： In this investigation, the authors describe the thermal conductivity, and electrical conductivity of solar glycol - water (50:50) mixture with MWCNTs. Gum Arabic was used as the surfactant to prepare a stable nanofluid suspension. The MWCNTs are dispersing with different volume concentrations of 0.2%, 0.4% and 0.6% prepared via a typical two-step methodology. The colloidal stability assessments were conducted through UV-vis spectrometer, zeta potential analyser, scanning electron microscopy analysis and pH metre. The maximum augmentation of thermal conductivity attained is (cid:1)21.46% at a loading of 0.6 vol.% of MWCNTs in SG - water mixture at 50(cid:3)C. However, the electrical conductivity of the prepared nanofluid linearly enhanced with increasing temperature. The electrical conductivity enhancements of (cid:1)62.19% at a loading of 0.6 vol.% of MWCNTs in SG – water mixture at 50?C. Results confirm that the SG-Water and MWCNTs based nanofluids can be used as a right replacement for the conventional liquids in various heat transfer applications.
关键词： Solar glycol,Thermal conductivity,Multiwalled carbon nanotubes,pH,Electrical conductivity
更新于2025-09-04 15:30:14
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Effect of Polyethylene Glycol Surface Charge Functionalization of SWCNT on the in vitro and in vivo Nanotoxicity and Biodistribution Monitored Noninvasively using MRI
摘要： The current study evaluated in vitro and in vivo toxicity of carboxyl or amine PEG surface functionalization of single walled carbon nanotubes (SWCNTs). Assessments of cytotoxicity, genotoxicity, immunotoxicity and oxidative stress were performed in vitro and in vivo (in a one-month follow-up study). The SWCNT biodistribution was investigated using noninvasive MRI. Results confirmed the enhanced biocompatibility of PEG-functionalized SWCNTs compared to non-functionalized materials with significant decreases (p<0.05) in the percentage of cell viability and increases in ROS generation, mitochondrial membrane potential, cell apoptosis, oxidative stress generation and oxidative DNA damage in vitro. PEG-functionalized SWCNTs with amine terminals were found to induce prominent increases in ROS generation, mitochondrial membrane potential, and oxidative stress compared to carboxy functionalized SWCNTs. No significant difference in the biodistribution of either PEG-COOH or PEG-NH2 functionalized SWCNTs was observed in MRI. In vivo assessments revealed a statistically significant increase (p<0.05) in oxidative stress as early as 24 h in serum and liver; however, all values normalized at 2 weeks’ investigation time point. DNA damage was minimal with either PEG-COOH or PEG-NH2 functionalized SWCNTs after two weeks’ exposure. The negatively charged SWCNTs caused lesser DNA damage compared to positively charged samples. Carboxy-functionalized SWCNTs did not caused substantial changes in inflammatory mediators and were found to be significantly safer than non-functionalized SWCNTs and may pave the way for novel biomedical applications in cancer diagnosis and therapy.
关键词： Nanotoxicity,Cytotoxicity,Carbon nanotubes,In vivo biodistribution,Magnetic Resonance Imaging
更新于2025-09-04 15:30:14