Fabrication of high-pore volume carbon nanosheets with uniform arrangement of mesopores

Carbon nanosheets with a tunable mesopore size,large pore volume,and good electronic conductivity are synthesized via a solution-chemistry approach.In this synthesis,diaminohexane and graphene oxide (GO) are used as the structural directing agents,and a silica colloid is used as a mesopores template.Diaminohexane plays a crucial role in bridging silica colloid particles and GO,as well as initiating the polymerization of benzoxazine on the surfaces of both the GO and silica,resulting in the formation of a hybrid nanosheet polymer.The carbon nanosheets have graphene embedded in them and have several spherical mesopores with a pore volume up to 3.5 cm3·g-1 on their surfaces.These nuerous accessible mesopores in the carbon layers can act as reservoirs to host a high loading of active charge-storage materials with good dispersion and a uniform particle size.Compared with active materials with wide particle-size distributions,the unique proposed configuration with confined and uniform particles exhibits superior electrochemical performance during lithiation and delithiation,especially during long cycles and at high rates.     

Designed synthesis of porous carbons for the separation of light hydrocarbons

The separation of light hydrocarbon mixtures (C₁-C₃) generated from petrochemical industry is vital and challenging process for obtaining valuable pure chemical feedstocks. In comparison to the energy intensive conventional separation technologies (cryogenic distillation, absorption and hydrogenation), the adsorptive separation is considered as a low energy cost and high efficiency process. Porous carbons have been demonstrated as excellent adsorbents for the separation of light hydrocarbons, owing to their designable structure and tailorable properties. This review summarizes the recent advances of using porous carbons as adsorbents for the separation of light hydrocarbons, including methane/nitrogen, methane/alkane, methane/carbon dioxide, ethylene/ethane and propylene/propane. We discuss the separation mechanisms and highlight the material features including pore structure, surface chemistry and target molecular properties that determine the separation performance. Furthermore, the challenges and development direction associated with carbonaceous adsorbents for light hydrocarbon separation are discussed, meanwhile the guidelines for the design of porous carbons are proposed.     

河南省消毒餐饮具中洗涤剂和大肠菌群安全现状及对策建议

目的 分析河南省消毒餐饮具的安全状况,对比不同洗消方式的效果,为餐饮具洗消标准的制定提供参考.方法 通过对2020年河南省消毒餐饮具的采样检测,按照抽检季节、餐饮单位类型、餐饮具种类等对结果进行分析研究,分析不合格原因,研究不同洗消方式对于检测结果的影响,形成对策建议.结果 全年餐饮具平均合格率为77.58％,夏季合格...     

Lysine-assisted rapid synthesis of crack-free hierarchical carbon monoliths with a hexagonal array of mesopores

The rapid and scalable synthesis of hierarchical carbon monoliths with an ordered mesostructure and fully interconnected macropores has been demonstrated. Resorcinol and formaldehyde based polymers were used as the carbon precursor, triblock copolymer Pluronic F127 as the structural directing agent, and organic base lysine as both the polymerization catalyst and mesostructure assembly promoter. In the presence of lysine, homogeneous and crack-free polymer monoliths can be obtained through rapid gelation in 15 min at 90 °C. The polymer monoliths have a robust framework, which can be directly dried at 50 °C in air and carbonized at high temperature under a nitrogen atmosphere. The carbon monoliths are crack-free and have an ordered mesostructure with fully interconnected macropores. The surface area and the macropore volume are high with values up to 600 m² g⁻¹ and 3.52 cm³ g⁻¹, respectively. Further steam activation of the carbon monolith can significantly improve the surface area to 2422 m² g⁻¹ while still maintaining the ordered mesostructure.     

Hard Carbon Nanosheets with Uniform Ultramicropores and Accessible Functional Groups Showing High Realistic Capacity and Superior Rate Performance for Sodium-Ion Storage

Hard carbon attracts considerable attention as an anode material for sodium-ion batteries; however, their poor rate capability and low realistic capacity have motivated intense research effort toward exploiting nanostructured carbons in order to boost their comprehensive performance. Ultramicropores are considered essential for attaining high-rate capacity as well as initial Coulombic efficiency by allowing the rapid diffusion of Na⁺ and inhibiting the contact of the electrolyte with the inner carbon surfaces. Herein, hard carbon nanosheets with centralized ultramicropores (≈0.5 nm) and easily accessible carbonyl groups (CO)/hydroxy groups (O H) are synthesized via interfacial assembly and carbonization strategies, delivering a large capacity (318 mA h g⁻¹ at 0.02 A g⁻¹), superior rate capability (145 mA h g⁻¹ at 5.00 A g⁻¹), and approximately 95% of reversible capacity below 1.00 V. Notably, a new charge model favoring fast capacitive sodium storage with dual potential plateaus is proposed. That is, the deintercalation of Na⁺ from graphitic layers is manifested as the low-potential plateau region (0.01−0.10 V), contributing to stable insertion capacity; meanwhile, the surface desodiation process of the CO and O H groups corresponds to the high-potential plateau region (0.40−0.70 V), contributing to a fast capacitive storage.     

The effect of carbon pore structure on the adsorption of cigarette smoke vapour phase compounds

The pore size, distribution and volume of activated carbon are extremely important for maximizing adsorption of vapours formed during cigarette smoking. Increasing micropore volume leads to an increase in the removal efficiency. Because of the relatively high flow rates encountered during the smoking process, mesopores appear to be beneficial as transport pores especially in cases where the micropore volume is relatively low and thus the most accessible micropore sites may be rapidly saturated. Film diffusion limitations seem to be present at the very high space velocities encountered in a filter under the conditions of cigarette smoking. The removal efficiency from smoke is approximately inversely proportional to the vapour pressure of the constituents.     

酒酿l号和2号酵母菌株的分离、鉴定及代谢产物分析

<正>酒酿是我国人民的传统发酵食品,它味道甘甜、酒味柔和,气味芳香,并含有多种维生素、氨基酸和有机酸,因此,深受我国江南人民的喜爱。为了深入地研究酒酿的发酵机理,进一步提高质量和风味,利于食用者的身体健康,本文仅从酵母菌的角度,剖析其区系及代谢产物的种类和含量。     

Synthesis of nanocast ordered mesoporous carbons and their application as electrode materials for supercapacitor

Various nanocast ordered mesoporous carbons (OMCs) were synthesized using mesoporous silicas such as SBA-15, SBA-16, KIT-6, SBA-3 and MCM-48 as templates via nanocasting pathway. The structures of OMCs were analyzed by X-ray diffraction, transmission electron microscope and nitrogen sorption technique. These OMCs with well-defined pore structure were used as model electrode materials for investigating the influence of pore structure on their double layer capacitances. The cyclic voltammetry and galvanostatic charge/discharge measurements were conducted to estimate the capacitive behaviour of OMCs. The results show that the mesopore structures of OMCs play an important role in improving surface utilization for the formation of electrical double layer. OMCs synthesized from SBA-15 and SBA-16 show great advantage over others because their micropores are being easy accessible through the mesopores, thus allowing rapid electrolyte ion diffusion. To achieve a higher specific capacitance (μF cm⁻²), the optimized amount ratio between micropore and mesopore needs to be controlled. In addition, great impact of the electrode disc thickness on the capacitive performance was demonstrated by a series of careful measurements.     

Microstructures of PAN-ACF modified by catalytic benzene deposition

Benzene pyrolysis was successfully introduced to modify the pore size distributions (PSD) of polyacrylonitrile based activated carbon fibers (PAN-ACF) into a sharp distribution, at the presence of nickel catalyst. The microstructures of samples were studied by means of nitrogen adsorption, XRD, and SEM. The nitrogen isotherms were analyzed in detail using the routine BET method, α_s plot, DR equation, Horvath-Kawazoe (HK) equation, and regularized density functional theory (DFT), by which the surface area, micropore volume, and PSD were obtained. The results showed that the pore size of PAN-ACF can be effectively narrowed by catalytic benzene deposition and the PSD showed a unimodal nature, exhibiting potential behavior as a molecular sieve. A fraction residue of catalyst located in the ultramicropores can be washed by acid, resulting in increased BET surface area and micropore volume, which can also be confirmed by XRD and SEM measurements.