High Efficiency Poly(acrylonitrile) Electrospun Nanofiber Membranes for Airborne Nanomaterials Filtration

The potential of poly(acrylonitrile) electrospun membranes with tuneable pore size and fiber distributions were investigated for airborne fine‐particle filtration for the first time. The impact of solution concentration on final membrane properties are evaluated for the purpose of designing separation materials with higher separation efficiency. The properties of fibers and membranes are investigated systematically: the average pore distribution, as characterized by capillary flow porometry, and thermo‐mechanical properties of the mats are found to be dependent on fiber diameter and on specific electrospinning conditions. Filtration efficiency and pressure drop are calculated from measurement of penetration through the membranes using potassium chloride (KCl) aerosol particles ranging from 300 nm to 12 μm diameter. The PAN membranes exhibited separation efficiencies in the range of 73.8–99.78% and a typical quality factor 0.0224 (1 Pa^?1) for 12 wt% PAN with nanofibers having a diameter of 858 nm. Concerning air flow rate, the quality factor and filtration efficiency of the electrospun membranes at higher face velocity are much more stable than for commercial membranes. The results suggest that the structure of electrospun membranes is the best for air filtration in terms of filtration stability at high air flow rate.

     

Novel Aerosol-Based Approach toward Mesoporous Silica Nanoparticles

This study introduces a novel gas-phase method for the synthesis of mesoporous silica nanoparticles (MSNs). The method is a two-step templating approach by first forming silicon-coated carbon structures in a hybrid microwave-plasma/hot-wall reactor followed by an annealing step to produce mesoporous silica with distinct nanostructure and porosity. Two different (sacrificial) carbonaceous templates have been prepared (plasma reactor) and coated (hot-wall reactor), 2D few-layer graphene (FLG) flakes and soot-like fractal aggregates. Results show that the wall thickness of the porous silica structures can be adjusted by changing the concentration of the silicon precursor (monosilane). High monosilane concentrations, however, result in solid silica particles after annealing. Using soot-like particle templates permitted to control of the shell thickness of the hollow porous particles, while the FLG template results in ultrathin silica sheets after heat treatment. The pore volume and specific surface area increase up to 263 m² g⁻¹ and 0.6 cm³ g⁻¹, respectively, by the formation of hollow porous particles. An adsorption study on carbamazepine reveals up to ≈86% removal. The gas-phase aerosol-based template method presented here offers scalability and versatility, and it is capable of producing MSNs with a controlled structure and porosity by modifying the carbonaceous templates.     

Manganese-based coordination framework derived manganese sulfide nanoparticles integrated with carbon sheets for application in supercapacitor

Manganese sulfide (MnS) with high specific capacitance and low-cost merits, has been investigated as a potential electroactive material for supercapacitor. However, in practical application, MnS has been suffering from some disadvantageous issues such as insufficient electrical conductivity, serious particle agglomeration as well as huge volume change during continuous charges and discharges, which resulted in a limited specific capacitance, shortened working life and inferior rate performance. Engineering electrode materials with controlled nanostructure and composition is pivotal to improve electrichemical performance of supercapacitors. This paper introduces a facile in situ sulfuration method to fabricate MnS/NSC composite with Mn-hexamethylene tetramine coordination framework as precursor. The results indicated that MnS nanoparticles were highly dispersed and incorporated into nitrogen, sulfur-doped carbon microsheets in MnS/NSC composite. Carbon matrix effectively dispersed and confined the MnS nanoparticles, thus inhibiting aggregation, relieving volume change and retaining structural integrity. Moreover, the 2D conductive carbon matrix reduced the diffusion distance for ions and ensured fast electron delivery. As a result, MnS/NSC electrode delivered a tremendously boosted electrochemical performance for supercapacitor. A large capacitance value about 1881.8F/g was achieved at 1A/g. Even cycling for 3000 loops at 40 A/g, MnS/NSC electrode retained a large capacitance of 404.3F/g. Furthermore, an asymmetric capacitor based on assembly of MnS/NSC composite cathode and activated carbon anode was fabricated. As tested under a current density of 0.1 A/g, it delivered a capacitance of ～ 110.1F/g and achieved an energy density of 12.4 Wh kg^?1 along with a power density of 3.03 kW kg^?1. These results demonstrate the potential utilization of MnS/NSC composite as electrodes for energy conversion and storage devices and open up a route for material design for future energy storage devices.     

A review on mechanisms and recent developments of nanomaterials based carbon fiber reinforced composites for enhanced interface performance

Carbon fiber reinforced composites have attracted lots of attention in many fields. However, on account of the poor infiltration of resin to carbon fiber, the weak interface performance between fiber and resin has been restricting the interface properties of composites. In recent progress, the review attaches more importance to the introduction of the third phase monomer, which mainly uses physical and chemical methods to assemble nanomaterials (such as carbon nanotubes, graphene, etc.) on the carbon fiber surface to modify the interface structure of the carbon fiber reinforced composites, and all of them have been demonstrated in this paper. Furthermore, the effects of introducing nanomaterials on the structure of the fiber/resin interface and the relationship between multi-scale interface structure and properties have been investigated. It can be seen that the design idea of researchers mainly uses one or more theories to improve the interface properties of carbon fiber reinforced composites, such as transition layer, chemical bonding, mechanical interlocking, infiltration, diffusion, and adsorption. In brief, this work provides some novel insights for the preparation of carbon fiber reinforced composites with excellent interlaminar shear strength.     

A new method of reinforcing graphene nanoplatelets in glass/epoxy composites

This research aims to develop a method for the amalgamation of graphene nanoplatelets in glass/epoxy composites. The poor interface bonding between the fiber and matrix is critical and hinders the full performance of the composites. Glass fabric and epoxy were used as reinforcement and matrix in the composite, respectively. Graphene nanoplatelets were utilized as an additional nano-materials filler for the composites. Glass/graphene/epoxy and glass/epoxy composites were fabricated via vacuum infusion molding. The new method of applying graphene nanoplatelets as secondary reinforcement in the composite was developed based on proper functionalization in the sonication process. The physical, tensile, flexural, and short beam interlaminar properties of fabricated composites were examined to analyze the method's effectiveness. The results showed that density decreased by around 5 %; however, thickness increased by around 34 % after introducing graphene nanoplatelets into the composites. The tensile strength and modulus of the composites declined by approximately 19 %, on the other hand, flexural strength and modulus increased by around 63.3 % and 8.3 %, respectively, after the addition of graphene nanoplatelets into the composites. Moreover, interlaminar shear strength of the composite was enhanced by approximately 50 %.     

酶的固载技术及纳米电化学酶生物传感器的研究进展

该文较详细地阐述了酶的固定化方法和各自的优缺点,以及综述了近年来各种类型的纳米材料在电化学酶生物传感器中的应用,并对今后的工作进行了展望.     

钙钛矿结构锰氧化物Pr_(1-x)Ca_xMnO_3(0.4≤x≤0.5)纳米材料的磁性质研究

采用溶胶凝胶法制备了Pr1-xCaxMnO3(0.4≤x≤0.5)系列纳米样品,对其磁性质进行了研究.所有样品在M-T曲线中250K附近的电荷有序转变和170K附近的顺磁-反铁磁转变都消失,与Dong等人的理论模拟计算相符.所有样品在40K都出现了Reentrant spin glass(RSG)态.随着Ca2+掺杂浓度的增加,Mn3+/Mn4+的比例迅速变小,破坏了Mn-O-Mn导电通道,导致磁化强度M逐渐变小.     

纳米材料改性沥青的研究状况和进展

纳米材料改性沥青的研究是道路交通材料研究中的热点和前沿课题,纳米粒子与沥青的相容性以及在沥青中的分散和稳定性是决定纳米材料改善沥青各项性能的关键。文中对近年来关于纳米材料改性沥青的各类研究进展进行介绍,总结不同研究内容的优势和存在的问题。对提高纳米粒子与沥青的相容性和分散性提出方案,最后对纳米材料改性沥青的研究前景进行展望。     

无机纳米多孔材料的研究进展

对无机纳米多孔材料的当前研究进展进行了评述,详细介绍了无机纳米多孔材料的应用前景、合成机理、合成方法,并特别介绍了非硅基多孔材料的研究进展,并对当前研究存在的问题进行了总结,最后就无机纳米多孔材料的研究方向进行了展望.