N, Cl-doped carbon dots (N, Cl-CDs) were prepared by hydrothermal method from rhodamine B (RhB) and ethylenediamine (EDA). The resulting N, Cl-CDs exhibited fascinating solvent dependence and strict excitation independence. As the polarity of the solvent increased (from tetrahydrofuran (THF) to water), the emission spectrum of N, Cl-CDs was redshifted and the fluorescence efficiency decreased, which were attributed to hydrogen bond-induced aggregation. Taking advantage of these attributes, the N, Cl-CDs were used as suitable probes for fluorescence and colorimetric dual-mode detection of water in THF. The linear relationship was 0.5–100% water with the detection limit down to 0.093%. Moreover, the sensing platform was converted into a paper-based sensor for handy, real-time, and visible humidity sensing. N, Cl-CDs/PVA films were fabricated and realized continuously tunable solid-state fluorescence, further expanding their practical application. Graphical abstract
Shujuan Zhang,Yanpeng Mao,Jian Sun,Tinglu Song,Zhanlong Song,Xiqiang Zhao,Wenlong Wang
In this research, N, Cl doped carbon quantum dots (CQDs) with triple-fluorescence centers was prepared by one-pot solvothermal method from waste traditional Chinese medicines as the raw material. The obtained N, Cl doped CQDs showed purple, yellow and red fluorescence under the 326, 380 and 578 nm excitation, respectively, of which red fluorescence was induced by the increase of concentrations and sensed rapidly water contents in 30–100% range with a limited of detection (LOD) of 0.65%. The obtained CQDs was applied for sensing Cr (Ⅵ) by triple channels, which exhibited the high selectivity and sensitivity for Cr (Ⅵ) with the LOD of 0.28, 0.87 and 0.90 μM, respectively. And its derivative materials exhibited the good linear range with 10–100 μM and 5–250 μM taking purple fluorescence as the response signal, respectively. The recoveries of N, Cl doped CQDs in tap water and sludge were in 93–110% range, suggesting a feasible avenue for accurate and rapid sensing of Cr (Ⅵ).
Yajuan Li,Tianchen Xia,Tingting Yu,Yingchun Miao,Meng Yang,Xiangyu Zhao,Liqun Ma
Iron oxide (Fe 2 O 3 ) is an intriguing anode material of electrochemical energy storage systems such as rechargeable batteries. The rational design of its nanostructure at mild condition to cope with the issues of low reversible capacity and sluggish kinetics is required. Herein, an efficient, facile, and potentially large-scale synthesis approach using the precursor of laminated iron oxychloride@polyaniline heterostructure and mild annealing is developed, yielding unique Fe 2 O 3 @carbon nanocomposites with hematite nanoparticles (∼20 nm) that embedded in nitrogen/chlorine-doped carbon nanodisk (N/Cl–C). Given the benefit of abundant active sites, good chemical contact between carbon and Fe 2 O 3 , and robust composite structure, the as-prepared Fe 2 O 3 @N/Cl–C anode material delivers competent lithium-ion storage properties, including high reversible capacity of 1010 mAh g −1 (based on the mass of the as-prepared nanocomposite) at 0.1 A g −1 , decent rate performance upon a rigorous current change, and superior cycling stability with 955 mAh g −1 after 180 cycles as well as a sustained Coulombic efficiency of about 99%. This structural design may provide a new avenue for achieving efficient iron oxide-based materials in chemical and electrochemical applications such as catalysis, lithium-ion batteries, and sodium-ion batteries.
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