Shujuan Zhang,Yanpeng Mao,Lai Wei,Zhanlong Song,Xiqiang Zhao,Wenlong Wang
The use of thermal conversion to convert Chinese patent medicines (CPM) residues into porous carbon-based materials and carbon dots (CDs) has effectively resolved the challenges associated with resource waste and environmental pollution while enhancing the added value of CPM residues. In this study, biochar and N-doped CDs with high quantum yield (QY) were simultaneously prepared from fermentation residues by employing a hydrothermal carbonization method without any chemical reagents . The obtained biochar had remarkable adsorption capacity, with an iodine adsorption value of 693.22 mg g –1 . The QY of N-doped CDs could reach to 36.17 % by the mean of self-doping due to the high nitrogen content of the fermentation residues. Considering the structural integrity and permeable porous structure of the two-dimensional leaf-like zeolitic imidazole framework (ZIF-L), N-doped CDs were encapsulated into ZIF-L to form novel fluorescent composites (N-doped CDs@ZIF-L). Moreover, N-doped CDs@ZIF-L as a novel fluorescent probe could be efficiently quenched in the presence of tetracycline (TC), doxycycline (DOC), and chlortetracycline (CTC) by static quenching and the inner filter effect . Notably, the fluorescent probe exhibited a good linear relationship with the TC, DOC, and CTC at 0–50, 0–50, and 0–45 μM, respectively, with limits of detection of 0.025, 0.033, and 0.027 μM, respectively. This probe could be employed to detect TC antibiotics in honey and milk, suggesting that it had the great potential for applications in environmental monitoring and food safety.
Fe–N–C catalysts have emerged as the most promising alternatives to commercial Pt/C catalysts for oxygen reduction reaction (ORR) due to their cost-effectiveness and favorable activity. Herein, a dual-site Fe/FeN x -NC catalyst was synthesized via a green, in situ doping strategy using two-dimensional Fe-doped ZIF-L as a nitrogen-rich precursor. The catalyst integrated Fe nanoparticles (NPs) and FeN x sites anchored on carbon nanotubes, intertwined with nitrogen-doped porous carbon nanosheets, achieving a high active site density and graphitisation. Electrochemical tests revealed that the optimized Fe/FeN x -NC-1 exhibited significant ORR activity, with a half-wave potential of 0.92 V and 0.80 V for alkaline and acidic medium, respectively. Zn-air batteries employing Fe/FeN x -NC-1 delivered a peak power density of 168 mW·cm −2 and a specific capacity of 790 mAh·g −1 , outperforming those of Pt-based catalysts. Density functional theory calculations demonstrated a reduced free energy barrier for the rate-determining step (0.48 eV) compared to single-site Fe–N 4 models (0.79 eV). The synergy between Fe NPs and FeN x optimized ORR intermediate adsorption and facilitated charge/mass transfer. This study offers valuable insights for the development of advanced energy conversion systems.
High separation performance and superior mechanical properties of the membranes are both of critical importance for membrane modules to achieve high efficiency and long-term stability. Herein, a series of mixed matrix membranes (MMMs) with brick-and-mortar architecture are prepared by incorporating two-dimensional zeolitic imidazolate framework-L (ZIF-L) nanosheets into polydimethylsiloxane (PDMS) matrix for separating alcohols (ethanol, n -propanol or n -butanol) from aqueous solution. The unique leaf-like morphology, flexible pore structure , and high hydrophobicity of ZIF-L nanosheets allow the straight and preferential permeation for alcohols; while the brick-and-mortar architecture renders the tortuous and intricate pathways for water, thus improving the membrane selectivity. Incorporating ZIF-L nanosheets endows the membranes with outstanding pervaporation performance, together with unusual and favorable increase in mechanical properties. More interestingly, the subtle interconnection of ZIF-L nanosheets creates the relatively continuous pathways for penetrants. Consequently, the resultant membrane displays a high separation factor (57.6) and a comparable permeation flux (402 g m −2 h −1 ) in separating 1.0 wt% n -butanol aqueous solution at 40 °C. Furthermore, the presence of ZIF-L nanosheets donates good thermal properties and promising long-term stability to the membranes. The findings of engineering brick-and-mortar architecture through two-dimensional porous fillers may provide new insights into designing high-performance MOF-based membranes for various applications.
危险品化学品经营许可证（带存储）