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Fluorescent Self-Healing Carbon Dot/Polymer Gels
摘要： Multicolor, fluorescent self-healing gels were constructed through reacting carbon dots produced from different aldehyde precursors with branched polyethylenimine. The self-healing gels were formed through Schiff base reaction between the aldehyde units displayed upon the carbon dots' surface and primary amine residues within the polyethylenimine network, generating imine bonds. The dynamic covalent imine bonds between the carbon dots and polymeric matrix endowed the gels with both excellent self-healing properties, as well as high mechanical strength. Moreover, the viscoelastic properties of the gels could be intimately modulated by controlling the ratio between the carbon dots and polymer. The distinct fluorescence emissions of the gels, originating from the specific carbon dot constituents, were employed for fabrication of light emitters at different colors, particularly generating white light.
关键词： imines,carbon dots,aldehydes.,dynamic covalent bonds,self-healing gels,fluorescent gels
更新于2025-09-23 15:23:52
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Preparation of graphene nanoribbons (GNRs) from twisted structure carbon nanotubes using unzipping technique
摘要： This work deals with the preparation of graphene nano ribbons (GNRs), which are small bars or strips of graphene with narrow range width less than 50 nm and one atom thick sheet (approximately 140 °A). This material has many applications in electronics, polymer composite, contrast agent bio-imaging and others. This material was prepared from twisted structure of carbon nanotubes CNTs using oxidation process by acids and breaking down by high frequency ultrasonication (sonochemical unzipping). Pre-prepared twisted CNTs were characterized by scanning electron microscope (HRSEM) before treatment. The size, morphology, crystallinity of prepared graphene nanoribbons was also investigated using transmission electron microscope, high resolution transmission electron microscope, and X-ray diffraction and particle size analyzer. The results showed of formation of GNRs with narrow width as lower than 29 nm and uniform sizes. X-ray diffraction reveals Bragg reflections corresponding to the lattice planes (002), (100), (101), (004), and (110) matched with hexagonal system of graphite.
关键词： sonochemical unzipping,Twisted carbon nanotubes,graphene nanoribbons
更新于2025-09-23 15:23:52
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Photocatalytic Degradation of Methylene Blue and Phenol Using TiO2/Activated-Carbon Composite Catalysts
摘要： Photocatalytic degradation of methylene blue and phenol were conducted separately in aqueous solutions using titania-activated carbon composites. Activated carbon composites of different textural features and light of different wavelength or energy were used in order explore their effects on the performance of titania-activated carbon catalysts. The catalysts (TiAC1, TiAC2 and TiAC3) were prepared by impregnating activated carbon supports with an aqueous suspension of titanium precursor (TiO2). The catalysts were characterized using BET, XRD and FTIR. The diffraction pattern showed strong peaks that are assigned to titanium anatase phase and weaker peaks that indicated low rutile phase. The FTIR showed broad peaks of Ti-O-Ti linkages in TiO2 particles. The photocatalytic degradation of methylene blue and phenol was performed separately in visible light and UV irradiation of different wavelengths. Adsorption was dominant in the case of methylene blue removal while photodecomposition was more pronounced in the case of phenol removal.
关键词： Photocatalysis,Phenol,Methylene blue,Titania,Activated carbon,Precursors
更新于2025-09-23 15:23:52
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Highly Luminescent Nitrogen-Doped Carbon Dots as “Turn-On” Fluorescence Probe for Selective Detection of Melamine
摘要： In our work, a new and simple method for selective detection of melamine is established by developing a "turn-on" fluorescence probe based on nitrogen-doped carbon dots (N-CQDs). The N-CQDs have been facilely prepared by one-step simple hydrothermal reaction and it is highly luminescent that with 51% fluorescent quantum yield. In this sensor, the fluorescent intensity of N-CQDs was found to be efficient quenched by Fe3+, upon addition of melamine the fluorescent intensity of N-CQDs-Fe3+ could gradually recover, which may because of the competitive combination of Fe3+ and melamine leading to the departure of Fe3+ from the N-CQDs' surface. Under optimum conditions, the fluorescence intensity has a good liner relationship with melamine in the range of 2.0 to 290 μM. The probe displayed good sensitivity toward melamine with a lower detection limit of 0.67 μM. In addition, this fluorescence probe has been used for the analysis of milk samples, demonstrating the fluorescence probe has potential application in the detection of melamine.
关键词： selective detection,turn-on fluorescence probe,melamine,carbon quantum dot
更新于2025-09-23 15:23:52
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Effects of Protonation, Hydroxylamination, and Hydrazination of g-C3N4 on the Performance of Matrimid?/g-C3N4 Membranes
摘要： One of the challenges to continue improving polymeric membranes properties involves the development of novel chemically modified fillers, such as nitrogen-rich 2-D nanomaterials. Graphitic carbon nitride (g-C3N4) has attracted significant interest as a new class of these fillers. Protonation is known to afford it desirable functionalities to form unique architectures for various applications. In the work presented herein, doping of Matrimid? with protonated g-C3N4 to yield Matrimid?/g-C3N4 mixed matrix membranes was found to improve gas separation by enhancing the selectivity for CO2/CH4 by up to 36.9% at 0.5 wt % filler doping. With a view to further enhancing the contribution of g-C3N4 to the performance of the composite membrane, oxygen plasma and hydrazine monohydrate treatments were also assayed as alternatives to protonation. Hydroxylamination by oxygen plasma treatment increased the selectivity for CO2/CH4 by up to 52.2% (at 2 wt % doping) and that for O2/N2 by up to 26.3% (at 0.5 wt % doping). Hydrazination led to lower enhancements in CO2/CH4 separation, by up to 11.4%. This study suggests that chemically-modified g-C3N4 may hold promise as an additive for modifying the surface of Matrimid? and other membranes.
关键词： carbon nitride,O2/N2,Matrimid? 5218,CO2/CH4,gas separation,mixed matrix membrane
更新于2025-09-23 15:23:52
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Phenanthroline-Derivative Functionalized Carbon Dots for Highly Selective and Sensitive Detection of Cu2+ and S2? and Imaging inside Live Cells
摘要： Developing effective methods for the instant detection of Cu2+ and S2? is highly desired in the biological and environmental fields. Herein, a novel fluorescent nanoprobe was elaborately designed and synthesized by grafting a phenanthroline derivative onto the surface of carbon dots (CDs). The obtained functionalized CDs (FCDs) exhibited blue fluorescence (FL) with excellent photostability and possessed a mean diameter around 4 nm. Cu2+ can be selectively captured by the phenanthroline group of FCDs to generate an absorptive complex in situ, leading to obvious quenching of the FCDs’ FL signal through an inner filter effect. Furthermore, the FL of the FCD–Cu2+ can be effectively recovered by S2? anions due to the release of FCDs from the FCD–Cu2+ complex owing to the formation of stable CuS (Ksp = 1.27 × 10?36) between S2? and Cu2+. The detection limits of the FCDs were determined to be 40.1 nM and 88.9 nM for Cu2+ and S2?, respectively. Moreover, this nanoprobe can also be used for the imaging of intracellular Cu2+ and S2?, which shows strong application prospects in the field of biology.
关键词： carbon dots,fluorescent nanoprobe,(2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid,Cu2+,S2?
更新于2025-09-23 15:23:52
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Activated carbons with adsorbed cations as photocatalysts for pollutants degradation in aqueous medium
摘要： Oxidized activated carbon (AC) based on commercial coconut-shell carbon Aquacarb 607C has been prepared. This AC has micro-mesoporous structure and contains surface carboxyl and phenol/enol groups. Cu- and Co-containing ACs have been synthesized via ion-exchange in acid medium. According to potentiometric titration and XPS data, cation-exchanged forms of AC contain about 0.5% of metal ions. Such cation-containing ACs possess narrowed band gap compared oxidized AC as it is observed for doped oxides. Oxidized and cation-containing ACs have been tested as catalysts in photodegradation of dyes and phenol under UV- and visible irradiation. Initial oxidized AC is photoactive toward rhodamine B and methyl orange under UV illumination but inactive under visible light. For the first time it is shown that cation-exchanged forms of AC have enhanced activity towards rhodamine B, methyl orange and phenol in both UV and visible region. Therefore, the principal possibility of improving the photocatalytic properties of AC by introducing a minimal amount of copper and cobalt cations is shown.
关键词： Cation-exchanged forms,Decolourisation and mineralization,UV and visible irradiation,Activated carbon,Photocatalytic degradation
更新于2025-09-23 15:23:52
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Manganese dioxide nanoparticles/activated carbon composite as efficient UV and visible-light photocatalyst
摘要： Manganese dioxide nanoparticles/activated carbon (MnO2/AC) composites and manganese dioxide nanoparticles (MnO2 NPs) are prepared through chemical reduction method. Morphological study shows that MnO2 NPs had cylindrical and spherical shape. The morphological study also revealed that MnO2 NPs were well dispersed on AC while neat Mn NPs present both in dispersed and in agglomerated form. The FT-IR study confirms the synthesis of MnO2 NPs. Zetasizer study presented that the Mn NPs had uniform size and below 100 nm in size and had zeta potential of ? 20 mV, which represent its stability in the suspension form. The synthesized Mn/AC composite and Mn NPs were utilized as photocatalysts for the photodegradation of Congo red (CR) dye. The degradation study shows that MnO2/AC composite degraded CR dye more efficiently than MnO2 NPs under UV and normal light irradiation. The efficient degradation of dye by Mn/AC composite is due to the synergistic effect between dye adsorption on AC and rapid photodegradation by supported MnO2 NPs. The results revealed that Mn/AC composite degraded about 98.53% of CR dye within 5 min while MnO2 NPs degraded 66.57% of dye within the same irradiation time. The recycled catalyst also significantly degraded dye which verifies its sustainability. The effect of catalyst dosage and initial dye concentration was conducted. The degradation rate of dye was found drastically faster in tap water (in presence of catalyst), which might be due to the presence of various mineral ions in the tap water.
关键词： Manganese dioxide,nanoparticles,Activated carbon,Photodegradation,Photocatalyst,Congo red
更新于2025-09-23 15:23:52
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Hybrid composite of CuO with $$\hbox {g}\hbox {-C}_{3}\hbox {N}_{4}$$g-C3N4 as a photoactive catalyst: an efficient approach for the oxidation of alcohols
摘要： An eco-friendly method for the oxidative transformation of alcohols to their corresponding carbonyl compounds by using g-C3N4@CuO as a photoactive heterogeneous catalyst has been developed. The catalyst was characterized by SEM-EDX, TEM, BET surface area measurements, powder XRD, FTIR, photoluminescence and UV-Vis spectroscopy. It was found to be very effective for the conversion of both primary and secondary alcohols into aldehydes and ketones with excellent yields using tert-butyl hydrogen peroxide (TBHP) as oxidant at room temperature in the presence of visible light in aqueous medium. The catalyst can be separated from the reaction mixture by simple centrifugation and reused up to five cycles without significant loss in activity.
关键词： Nanocomposite,alcohol oxidation,copper oxide,photocatalyst,graphitic carbon nitride
更新于2025-09-23 15:23:52
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Characterization of atypical polyaniline nano-structures prepared via advanced techniques
摘要： Conductive polymers had been the topic of a vast number of investigations during the last decades, so, the synthesis of conducting polymers and study of their physical properties has been of prime importance. One of these conductive polymers is polyaniline. The current work is to prepare polyaniline (PANI) nanostructured material via four different preparation techniques which were sol-gel, rapid mixing, sonochemical and supercritical carbon dioxide (SC-CO2) assisted polymerization. The morphology of the prepared PANI samples was determined using Transmission electron microscopy (TEM) and Scanning Electron Microscope (SEM). The molecular structure of prepared PANI samples was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The electrical conductivity of the synthesized samples was assessed by using the four-probe method at room temperature. The surface area of the prepared samples was determined using Brunauer Emmett Teller (BET). The characterization results of the prepared PANI con?rm that the morphology, chemical composition, crystallinity, conductivity and surface area were altered signi?cantly as a consequence of its synthesis via atypical techniques.
关键词： Supercritical carbon dioxide assisted polymerization,Nanoparticles,Sonochemical,Polyaniline nano-structures,Nano?bers,Polyaniline characterization,Nanorods,Sol gel,Rapid mixing polymerization
更新于2025-09-23 15:23:52