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151.
The flexible stretchable sensors have great potential for implementation in various applications, such as intelligent soft robots, health monitoring, and motion detection. However, most of the flexible stretchable sensors with microstructures and high sensitivities are fabricated by expensive templates and complex processes. In consideration of large-scale fabrication, a low cost and efficient way is in great demand. Herein, electroless plating on Nafion films with decent swelling ratios are proposed to fabricate stretchable sensors with wrinkle-structured electrodes. By adding isopropanol (IPA) to the electroless plating process, the H2O-IPA sensor with larger swelling ratio shows deeper surface wrinkles, higher surface roughness, and better sensitivity to strain. At the same time, the H2O-IPA sensor exhibit good durability (500 cycles). By mounting the sensor on the joint of human finger, the motion of the finger bending and even the bending degree can be accurately detected, indicating the potential use in the field of wearable devices and soft electronic skins. 相似文献
152.
X.-T. Mu Y.-S. Ouyang L.-M. Pei Z.-X. Peng S.-Q. Shao S.-M. Wang H. Xiong Y. Xiao Q.-Y. Yang 《Materials Today Chemistry》2022
Adsorptive separation of C2H6 from C2H4 by adsorbents is an energy-efficient and promising method to boost the polymer grades C2H4 production. However, that C2H6 and C2H4 display very similar physical properties, making their separation extremely challenging. In this work, by regulating the pore environment in a family of chitosan-based carbon materials (C-CTS-1, C-CTS-2, C-CTS-4, and C-CTS-6)- we target ultrahigh C2H6 uptake and C2H6/C2H4 separation, which exceeds most benchmark carbon materials. Explicitly, the C2H6 uptake of C-CTS-2 (166 cm3/g at 100 kPa and 298 K) has the second-highest adsorption capacity among all the porous materials. In addition, C-CTS-2 gives C2H6/C2H4 selectivity of 1.75 toward a 1:15 mixture of C2H6/C2H4. Notably, the adsorption enthalpies for C2H6 in C-CTS-2 are low (21.3 kJ/mol), which will facilitate regeneration in mild conditions. Furthermore, C2H6/C2H4 separation performance was confirmed by binary breakthrough experiments. Under different ethane/ethylene ratios, C-CTS-X extracts a low ethane concentration from an ethane/ethylene mixture and produces high-purity C2H4 in one step. Spectroscopic measurement and diffraction analysis provide critical insight into the adsorption/separation mechanism. The nitrogen functional groups on the surface play a vital role in improving C2H6/C2H4 selectivity, and the adsorption capacities depend on the pore size and micropore volume. Moreover, these robust porous materials exhibit outstanding stability (up to 800 °C) and can be easily prepared on a large scale (kg) at a low cost (~$26 per kg), which is very significant for potential industrial applications. 相似文献
153.
Dications of cycloparaphenyles ([n]CPPs) are known to exhibit in-plane global aromaticity, contained in a nanobelt structure. Recently synthesized ortho and meta isomers of [n]CPPs break the radial symmetry of π structure incorporating perpendicular oriented π orbitals. Herein we set to explore the aromaticity of neutral and dicationic ortho and meta isomers of [8]CPP by dissecting the induced magnetic field to contributions of the twofold radial/perpendicular π system using delocalized canonical molecular orbitals (CMO), and introducing the natural localized molecular orbitals (NLMO) analysis with DFT methods. The dications sustain a reduced global aromatic character of the radial π system under a perpendicular orientation of the external field which declines from ortho to meta isomer and reinforces local aromaticity of ortho ring while it destroys aromaticity of meta ring. Aromaticity variations are determined by symmetry governed rotational excitations of frontier π orbitals. The parallel orientation reveals a substantial reduction of local aromaticity verified with NICSπ analysis and electron delocalization indices. 相似文献
154.
155.
We predict, by means of ab initio calculations, stable electron and hole polaron states in perfect monoclinic HfO2. Hole polarons are localized on oxygen atoms in the two oxygen sublattices. An electron polaron is localized on hafnium atoms. Small barriers for polaron hopping suggest relatively high mobility of trapped charges. The one-electron energy levels in the gap, optical transition energies and ESR g-tensor components are calculated. 相似文献
156.
157.
研究高活性和稳定性的非贵金属基析氢催化剂对解决当前能源危机和环境污染问题具有重要意义.碳化钨具有与贵金属Pt类似的d带电子结构,因而成为一类新兴的非贵金属析氢催化剂,受到广泛关注.磷掺杂是提高催化剂析氢活性的有效方法之一,然而目前最常见的构筑磷掺杂方法是使用多金属氧酸盐(POMs,如H3PW12O40),其固定的W/P原子比导致W2C中的掺杂浓度难以调控,并且磷掺杂主要是进入碳载体而不是碳化物本身,从而导致无法明确杂原子对其电催化析氢活性的贡献.本文采用植酸(PA)为磷源设计合成了可控磷掺杂W2C纳米颗粒,并探讨了催化剂组分、杂原子掺杂位置与析氢性能之间的关系.深入研究了磷掺杂碳化钨(WCP)的化学结构和析氢活性.与原始的W2C催化剂相比,WCP具有更高的本征活性、更快的电子转移速率和更多的活性位数量,并且在酸性和碱性条件下均表现出较好的析氢性能.特别是过电位为-200 mV时,WCP催化剂的本征活性在酸性和碱性条件下分别为0.07和0.56 H2 s-1,高出纯W2C(0.01和0.05 H2 S-1)数倍.同时,在电流密度为-10 mA cm-2时,优化后的WCP催化剂在酸性和碱性条件下的析氢过电位分别降低了96和88 mV.XPS及EDS元素分析结果表明,随磷源添加量增加,磷掺杂从碳化钨表面逐渐向内部扩散,进一步说明磷取代位置与析氢活性之间的构效关系,高浓度的表面磷取代可以加速质子捕获过程,从而显著提高其析氢活性,而过量的内部磷取代会破坏W2C结构,降低电子转移速率,从而导致析氢性能下降.利用密度泛函理论计算深入研究了WCP具有较好析氢性能的原因,与内部磷取代相比,表面磷取代会使碳化钨表现出更合适的氢吸附自由能,并且更加有效地降低了氢释放势垒,从而优化了析氢反应动力学.综上,本文为元素掺杂工艺提供了新的思路,同时研究了表面异质原子对析氢活性的关键作用,为该类催化材料的构效关系研究提供了新思路. 相似文献
158.
Mubashir Hussain Zhen Chen Mu Lv Jingyi Xu Xiaohan Dong Jingzhou Zhao Song Li Yan Deng Nongyue He Zhiyang Li Bin Liu 《中国化学快报》2021,31(12):3163-3167
The rapid identification of pathogens is crucial in controlling the food quality and safety. The proposed system for the rapid and label-free identification of pathogens is based on the principle of laser scattering from the bacterial microbes. The clinical prototype consists of three parts: the laser beam, photodetectors, and the data acquisition system. The bacterial testing sample was mixed with 10 mL distilled water and placed inside the machine chamber. When the bacterial microbes pass by the laser beam, the scattering of light occurs due to variation in size, shape, and morphology. Due to this reason, different types of pathogens show their unique light scattering patterns. The photo-detectors were arranged at the surroundings of the sample at different angles to collect the scattered light. The photodetectors convert the scattered light intensity into a voltage waveform. The waveform features were acquired by using the power spectral characteristics, and the dimensionality of extracted features was reduced by applying minimal-redundancy-maximal-relevance criterion (mRMR). A support vector machine (SVM) classifier was developed by training the selected power spectral features for the classification of three different bacterial microbes. The resulting average identification accuracies of E. faecalis,E. coli and S. aureus were 99%, 87%, and 94%, respectively. The overall experimental results yield a higher accuracy of 93.6%, indicating that the proposed device has the potential for label-free identification of pathogens with simplicity, rapidity, and cost-effectiveness. 相似文献
159.
160.
André L. Santos Regina M. Takeuchi Rodrigo A. A. Muñoz Lúcio Angnes Nelson R. Stradiotto 《Electroanalysis》2014,26(2):233-242
This article critically reviews the electroanalytical methods devoted for the determination of organic compounds in automotive fuels that can range from contaminants to additives typically introduced into liquid biofuels and liquid fossil fuels. Contaminants such as aldehydes and ketones in bioethanol, free fatty acids and glycerol in biodiesel, and sulfur and nitrogen organic compounds in gasoline and diesel fuel, and additives such as colour markers and antioxidants added to fuels were determined by electroanalytical methods. Special focus is given to electrodes, electrochemical techniques, and sample preparation strategies. Future directions of research on electroanalysis of liquid fuels are presented. 相似文献