A facile, scalable route to new nanocomposites that are based on carbon nanotubes/heteroatom‐doped carbon (CNT/HDC) core–sheath nanostructures is reported. These nanostructures were prepared by the adsorption of heteroatom‐containing ionic liquids on the walls of CNTs, followed by carbonization. The design of the CNT/HDC composite allows for combining the electrical conductivity of the CNTs with the catalytic activity of the heteroatom‐containing HDC sheath layers. The CNT/HDC nanostructures are highly active electrocatalysts for the oxygen reduction reaction and displayed one of the best performances among heteroatom‐doped nanocarbon catalysts in terms of half‐wave potential and kinetic current density. The four‐electron selectivity and the exchange current density of the CNT/HDC nanostructures are comparable with those of a Pt/C catalyst, and the CNT/HDC composites were superior to Pt/C in terms of long‐term durability and poison tolerance. Furthermore, an alkaline fuel cell that employs a CNT/HDC nanostructure as the cathode catalyst shows very high current and power densities, which sheds light on the practical applicability of these new nanocomposites. 相似文献
A low-operating voltage and high performance polymeric field effect transistors using octadecylphosphonic acid-treated high-k AlOx and HfO2 hybrid dielectrics were demonstrated. High-k metal oxide hybrid dielectrics were prepared by oxygen plasma treatment of deposited Al film for AlOx and by spin coating of solution-processable HfO2 sol-gel solution for HfO2 in combination with phosphoric acid-based self-assembled monolayer (SAM), resulting in high capacitance (10 nF/cm2 for SiO2, 600 nF/cm2 for AlOx and 580 nF/cm2 for HfO2). With phosphoric acid-based SAM on high-k metal oxide and thermal annealing of thieno[3,2-b]thiophene-based conducting polymer, the device performance was significantly enhanced. The highest mobility of the transistors using ODPA-treated AlOx as a gate dielectric is 2.3 × 10?2 cm2 V?1 s?1 in the saturation region with the source-drain of ?2 V. In ODPA-treated HfO2 hybrid dielectric, the saturated mobility is 1.1 × 10?2 cm2 V?1 s?1 and the threshold voltage was measured to be ?0.31 V, which is at least one order lower than SiO2 hybrid dielectric (?3 V). 相似文献
We report on the fabrication of efficient annealing-free organic solar cells using co-solvent solution considered as a promising method for low-cost and time-saving manufacturing. Higher device efficiency could be obtained compared to the pure solvent casted device, resulting from the improved crystallinity, optical absorption and transport properties. The power conversion efficiency of 2.8% was obtained, demonstrating the feasibility of achieving low-cost and high-efficiency organic solar cells without any additional treatment and processing additives. 相似文献
Water transport is critical to the successful implementation of polymer electrolyte fuel cells (PEFC), especially in long-term and dynamic operation in automotives. Liquid water appears in the fuel cells not only from the water generated at the cathode catalyst layer but also as a result of condensation of water vapor from the humidified gases. In this study, we report a simple approach to prepare a superhydrophobic gas diffusion layer by chemical vapor deposition of polydimethylsiloxane without significant change in pore size of gas diffusion layer unlike other approach adding hydrophobic agent such as polytetrafluoroethylene. A superhydrophobic coating on the GDL can be obtained, leading to exceptionally enhanced power performance and stability of PEFC especially at a high current where water transport becomes more critical. 相似文献
A m-xylene bridged imidazolium receptor 1 has been designed and synthesized. The receptor 1 utilizes two imidazole (C–H)+—anion hydrogen bonds and one aromatic hydrogen—anion hydrogen bond. The major driving force of complexation between the receptor 1 and anions comes from two imidazole (C–H)+—anion hydrogen bonding. However, some hydrogen bonding energy between aromatic hydrogen and anion exists, although it is expected to be much smaller than that of imidazole (C–H)+—anion hydrogen bonds. 相似文献
An arginine‐leucine block copolypeptide (R60L20) is synthesized, which is capable of forming vesicles with controllable sizes, able to transport hydrophilic cargo across the cell membrane, and exhibit relatively low cytotoxicity. The R60L20 vesicles also possess the ability to deliver DNA into mammalian cells for transfection. Although the transfection efficiency is lower than that of the commercially available transfection agent Lipofectamine 2000, the R60L20 vesicles are able to achieve transfection with significantly lower cytotoxicity and immunogenicity. This behavior is potentially due to its stronger interaction with DNA which subsequently provides better protection against anionic heparin.
Micro‐RNAs (miRNAs) are small, endogenous, singlestranded, and noncoding RNAs. The miRNAs have been found to perform important functions in many cellular processes, such as development, proliferation, differentiation, and apoptosis. Circulating miRNAs have been proposed as emerging biomarkers in diseases such as cancer, diabetes, and cardiovascular disease including acute myocardial infarction (AMI). In this study, we developed CE with LIF (CE‐LIF) using fluorescence‐labeled DNA probe for determination of low abundance miRNA in cell extracts. The target miRNA is miRNA‐499, a biomarker candidate of AMI with low abundance in biological samples. In order to measure the trace level of miRNA, we optimized the hybridization conditions such as hybridization time, temperature, and buffer solution. The highest fluorescence intensity of the hybridized miRNA‐499 was found when hybridization was conducted at 40°C in 50 mM Tris‐acetate (pH 8.0) buffer containing 50 mM NaCl, and 10 mM EDTA for 15 min. The hybridized miRNA‐499 was detected in cultured H9c2 cardiomyoblast cells and the analysis of miRNA‐499 was completed within 1 h using CE‐LIF. These results showed the potential of CE for fast, specific, and sensitive high‐throughput analysis of low‐abundance miRNAs in cell extracts, biofluids, and tissues. 相似文献