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Nitrogen-Doping Chemical Behavior of Graphene Materials with Assistance of Defluorination
摘要： Heteroatom-doping reactions are essential to achieve advanced graphene-based materials for energy and biological areas. Unfortunately, considerably less is known regarding the detailed reaction pathways up to now. Here, we focus on investigating the nitrogen (N) doping process of fluorinated graphene (FG) under the assistance of defluorination based on modified in situ fourier transform infrared spectroscopy. It was demonstrated FG possesses a higher and more effective reactivity with ammonia in comparison with other graphene derivatives, which enable N-doping to proceed efficiently with assistance of defluorination even at a lower temperature (16.8 at % of N at 300 °C, 19.9 at % of N at 400 °C). Combining with Density functional theory, it was proved that, at the initial reaction step of N-doping, ammonia molecule attacked and substituted the C-F of FG by the new C-NH2. Sequentially, amino group was cyclized to the three-membered ring of ethylenimine. More importantly, the dissociation and migration of C-F bonds facilitates the dissociating of C-C bonds and the recombining of C-N bonds, thus significantly promoting the N atom in ethylenimine ring to transform to the pyridinic-N or graphitic-N in graphene skeleton.
关键词： Fluorinated graphene,Reaction pathway,Defluorination,Nitrogen doping,Two-dimensional chemistry
更新于2025-09-04 15:30:14
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Nitrogen-Doped Durian Shell Derived Carbon Dots for Inner Filter Effect Mediated Sensing of Tetracycline and Fluorescent Ink
摘要： Photoluminescent carbon dots have gained increasing attention in recent years due to their unique optical properties. Herein, a facile one-pot hydrothermal process is used to develop nitrogen-doped carbon dots (NCDs) with durian shell waste as the precursor and Tris base as the doping agent. The synthesized NCDs showed a quantum yield of 12.93% with a blue fluorescence under UV-light irradiation and maximum emission at 414 nm at an excitation wavelength of 340 nm. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy showed the presence of nitrogen and oxygen functional groups on the NCD surface. The particles were quasi-spherical with an average particle diameter of 6.5 nm. The synthesized NCDs were resistant to photobleaching and stable under a wide range of pH but were negatively affected by increasing temperature. NCDs showed high selectivity to Tetracycline as the fluorescence of NCDs was quenched significantly by Tetracycline as a result of the inner filter effect. Based on sensitivity experiments, a linear relationship (R2 = 0.989) was developed over a concentration range of 0–30 μM with a detection limit of 75 nM (S/N = 3). The linear model was validated with two water samples (lake water and tap water) with relative recoveries of 98.6–108.5% and an RSD of <3.5%.
关键词： Fluorescent ink,Tetracycline detection,Durian shell waste,Nitrogen doping,Carbon dots
更新于2025-09-04 15:30:14
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Modification of the Optical and Electronic Properties of TiO2 By N Anion-Doping for Augmentation of the Visible Light Assisted Photocatalytic Performance
摘要： In this work, a nitrogen-doped anatase TiO2 nanocrystal is prepared by a modified sol-gel preparation method using the nonionic surfactant (polyoxyethylene sorbitan monooleate) as a structural controller and a soft template. The as-prepared samples are characterized by X-ray diffraction, Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy techniques. Then the photocatalytic activity of these samples is assessed by the photocatalytic oxidation of phenol under visible light irradiation. The phenol concentration is measured using a UV-Vis spectrometer. Experimental results show that N-doping leads to an excellent visible light photocatalytic activity of the TiO2 nanocatalyst. Furthermore, the formation energy and electronic structure of pure and N-doped anatase TiO2 are described by density functional theory (DFT) calculations. It is found that N-doping narrowed the band gap of bare TiO2, which leads to an excellent visible light photocatalytic activity of N–TiO2 nanocatalysts. Therefore, the prepared N–TiO2 photocatalyst is expected to find the use in organic pollutant degradation under solar light illumination.
关键词： nitrogen doping,DFT simulation,photocatalysis,titania
更新于2025-09-04 15:30:14