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71.
Lei Sun Jiahui Geng Dr. Mengyou Gao Dr. Dehua Zheng Zhongxin Jing Qingyun Zhao Prof. Jianjian Lin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(42):10998-11004
Fe0.95S1.05 with high reactivity and stability was incorporated into WS2 nanosheets via a one-step solvothermal method for the first time. The resulted hybrid catalyst has much higher catalytic activity than WS2 and Fe0.95S1.05 alone, and the optimal WS2/Fe0.95S1.05 hybrid catalyst was found by adjusting the feed ratio. The addition of Fe0.95S1.05 was proven to be able to enhance the hydrogen evolution reaction (HER) activity of WS2, and vice versa. At the same time, it was found that the catalytic effect of the hybrid catalyst was the best when the feed ratio was W : Fe=2 : 1. In other words, we confirmed that there is a synergistic effect between W- and Fe-based sulfide hybrid catalysts, and validated that the reason for the improved HER performance is the strong interaction between the two in the middle sulfur. WS2/Fe0.95S1.05-2 hybrid catalyst leads to enhanced HER activity, which shows a low overpotential of ∼0.172 V at 10 mA cm−2, low Tafel slope of ∼53.47 mV/decade. This study supplies innovative synthesis of a highly active WS2/Fe0.95S1.05 hybrid catalyst for HER. 相似文献
72.
Mingfang Li Rong Geng Meichuan Liu Dongming Li 《International journal of environmental analytical chemistry》2013,93(8):571-582
Bovine serum albumin (BSA) was covalently attached to glassy carbon electrode (GCE) surface by the electrochemical method. An enhancement for the redox of hydroquinone (HQ) on BSA/GCE was confirmed by cyclic voltammetry and electrochemical impedance spectroscopy measurement. The electron transfer rate constant (k s) on the BSA/GCE electrode is almost three orders of magnitude higher than that on bare GCE. The enhancing effect can be attributed to the electrostatic force between the positively charged HQ and negatively charged BSA. It is found that the enhanced redox process of HQ can be used to determine HQ sensitively. The oxidation current can reach 95% of its steady-state value within 30 s. The linear range for HQ determination is from 2.5 × 10?8 M to 1.325 × 10?6 M with a detection limit of 8.6 × 10?9 M at a signal-to-noise ratio of 3. The study may provide a simple, rapid and sensitive method for determination of HQ which is present in the natural environment and in chemical industry effluent. 相似文献
73.
A series of 4-[(4-n-polyfluoroalkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]phenyl fluoro-substituted benzoate liquid crystals have been synthesized. Their phase transition temperatures have been measured by optical polarizing microscopy and confirmed by DSC. The results show that a highly fluorinated terminal chain impairs mesomorphic properties. 相似文献
74.
Lei Sun Tian Du Cheng Wang Prof. Dongling Geng Dr. Lin Li Prof. Yang Han Prof. Yunfeng Deng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(69):17437-17443
Low-bandgap organic semiconductors have attracted much attention for their multiple applications in optoelectronics. However, the realization of narrow bandgap is challenging particularly for small molecules. Herein, we have synthesized four quinoidal compounds, i. e., QSN3 , QSN4 , QSN5 and QSN6 , with electron rich S,N-heteroacene as the quinoidal core and indandione as the end-groups. The optical bandgap of the quinoidal compounds is systematically decreased with the extension of quinoidal skeleton, while maintaining stable closed-shell ground state. QSN6 absorbs an intense absorption in the first and second near-infrared region in the solid state, and has extremely low optical bandgap of 0.74 eV. Cyclic voltammetry analyses reveal that the lowest unoccupied molecular orbital (LUMO) energy levels of the four quinoidal compounds all lie below −4.1 eV, resulting in good electron-transporting characteristics in organic thin-film transistors. These results demonstrated that the combination of π-extended quinoidal core and end-groups in quinoidal compounds is an effective strategy for the synthesis of low-bandgap small molecules with good stability. 相似文献
75.
Yu-Huan Geng Dr. Yuan-Zhao Hua Dr. Shi-Kun Jia Prof. Dr. Min-Can Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(16):5130-5135
The first regio-, diastereo-, and enantioselective direct Mannich reaction of β,γ,-unsaturated ketones with benzoxazinone cyclic imines was enabled by Lewis acid/Brønsted base cooperative catalysis. The dinuclear zinc complex catalyzed the reaction of a broad range of β,γ-unsaturated ketones to proceed at the α-site exclusively, leading to corresponding adducts with two consecutive tertiary carbon stereocenters in diastereomeric ratios of up to >20:1 and enantioselectivities generally in the 90–99 % ee range. These products were used as general intermediates in the synthesis of multisubstituted cyclocanalines, tetrahydro pyridazinones, and 4H-furo[2,3-b][1,4]benzoxazine derivatives. 相似文献
76.
Difference systems of sets (DSS) are combinatorial configurations that arise in connection with code synchronization. This paper proposes a new method to construct DSSs, which uses known DSSs to partition some of the cosets of Zv relative to subgroup of order k, where v = km is a composite number. As applications, we obtain some new optimal DSSs. 相似文献
77.
78.
Synthesis of ethylene/vinyl ester copolymers with pendent linear branches via ring‐opening metathesis polymerization of fatty acid‐derived cyclooctenes 下载免费PDF全文
Yuchen Feng Suyun Jie Bo‐Geng Li 《Journal of polymer science. Part A, Polymer chemistry》2017,55(13):2211-2220
Fatty acid‐derived cyclooctenes, including n‐hexanoic acid ( M1 ), n‐octanoic acid ( M2 ), lauric acid ( M3 ), and palmitic acid ( M4 ), were prepared as monomers and polymerized by ring‐opening metathesis polymerization (ROMP) using Grubbs second‐generation catalyst ( G2 ). In all the cases, the regio‐irregular unsaturated polymers with pendent linear branches were obtained, which could be saturated by chemical hydrogenation with TSH/TPA in high conversion, yielding ethylene/vinyl ester copolymers with pendent linear branches on precisely every eighth backbone carbon. Both unsaturated and saturated polymers were amorphous, and their structures were characterized by FTIR, 1H and 13C NMR spectra, and elemental analysis. Differential scanning calorimetry (DSC) and thermo‐gravimetric analysis (TGA) were used to study their thermal properties. The chain length of branches greatly affected the thermal properties of polymers. After hydrogenation, the thermal degradation stability of polymers was relatively improved. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2211–2220 相似文献
79.
电子回旋共振(ECR)中和器是微型ECR离子推力器的重要组成部分,其引出的电子用于中和ECR离子源的离子束流,避免了航天器表面电荷堆积,并且电子引出性能对推力器的整体性能起着重要作用.为了分析影响微型ECR中和器电子引出的因素,本文建立了二维轴对称PIC/MCC计算模型,通过数值模拟研究不同磁路结构对中和器的电子引出,及不同腔体长度对壁面电流损失的影响.计算结果表明, ECR区位置和引出孔附近磁场构型对中和器的电子引出性能至关重要.当ECR区位于天线上游,电子在迁移扩散中易损失,并且电子跨过引出孔前电势阱所需的能量更高.如果更多磁力线平行通过引出孔,中和器引出相同电子电流所需电压较小.当ECR区被天线切割或位于下游时,电子更易沿磁力线迁移到引出孔附近,从而降低了收集板电压.研究了同一磁路结构下不同腔体长度对电子引出的影响,发现增加腔体长度,使得更多平行轴线的磁力线通过引出孔从而避免电子损失在引出板表面,增加了引出电子电流.研究结果有助于设计合理的中和器磁路和腔体尺寸. 相似文献
80.