摘要：
Indium oxide (In2O3) doped zinc oxide (ZnO) nanocomposites were successfully synthesized through a facile microwave hydrothermal method. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N-2 adsorption-desorption isotherms (BET) and UV-Vis diffuse reflectance spectroscopy. The morphology of In2O3-ZnO composites was observed to be like flowers, and the diameter of particles constituting the porous petal was about 30 nm. The photoelectrocatalytic test results showed that the photoelectrocatalytic methylene blue (MB) degradation efficiency using In2O3-ZnO nanocomposites as photocatalysts under visible light irradiation and a certain voltage could reached above 95.3% after 60 min, much higher than that of In2O3 particles and ZnO particles. The enhanced photoelectrocatalytic activity was attributed to the doping of In2O3 and applied voltage, which beneficially reduced the recombination of electrons and holes in the photoelectrocatalytic process, therefore, it promoted the production of active species (center dot OH and center dot O-2(-)). (C) The Author(s) 2019. Published by ECS.
摘要：
Flexible and stretchable conducting composites that can sense stress or strain are needed for several emerging fields including human motion detection and personalized health monitoring. Silver nanowires (AgNWs) have already been used as conductive networks. However, once a traditional polymer is broken, the conductive network is subsequently destroyed. Integrating high pressure sensitivity and repeatable self-healing capability into flexible strain sensors represents new advances for high performance strain sensing. Herein, superflexible 3D architectures are fabricated by sandwiching a layer of AgNWs decorated self-healing polymer between two layers of polydimethylsiloxane, which exhibit good stability, self-healability, and stretchability. For better mechanical properties, the self-healing polymer is reinforced with carbon fibers (CFs). The sensors based on self-healing polymer and AgNWs conductive network show high conductivity and excellent ability to repair both mechanical and electrical damage. They can detect different human motions accurately such as bending and recovering of the forearm and shank, the changes of palm, fist, and fingers. The fracture tensile stress of the reinforced self-healing polymer (9 wt% CFs) is increased to 10.3 MPa with the elongation at break of 8%. The stretch/release responses under static and dynamic loads of the sensor have a high sensitivity, large sensing range, excellent reliability, and remarkable stability.
摘要：
Informatics analysis on inorganic compounds, surface imaging and depth profiling were carried out for PM2.5 using time-of-flight secondary ion mass spectrometry (TOF-SIMS) during different haze periods (autumn and winter). Both positive ions, such as NH4+, Si+, H+, Li+, Na+, Mg+, Al+, K+, Ca+, Ti+, Cr+, Fe+, Cu+, As+, Cs+ and Ba+, and negative ions, such as NO2-, NO3-, SO32-, SO42-, O-, Cl-, CN- and H-, were detected in the samples. Along with the increase of the depth, the signal intensity became weaker and weaker for most of the inorganic ions, however, it could be stronger for a few of them due to the variation of chemical behaviors. Moreover, the source analysis was performed, and the results indicated that PM2.5 was mainly derived from biomass combustion and fossil combustion in this area. This paper is useful to provide a tool to study the PM2.5 around the world.
期刊：
Journal of Materials Research,2019年34(17):3030-3039 ISSN：0884-2914
通讯作者：
Shi, Minjie
作者机构：
[Shi, Minjie; Narayanasamy, Mugilan; Liu, Yongchao; Wu, Hanzhao; Yan, Chao] Jiangsu Univ Sci & Technol, Sch Mat Sci & Engn, Zhenjiang 212003, Jiangsu, Peoples R China.;[Yang, Cheng] Shanghai Jiao Tong Univ, State Key Lab Metall Matrix Composite Mat, Sch Mat Sci & Engn, Shanghai 200240, Peoples R China.;[Xie, Wei] Changsha Univ Sci & Technol, Key Lab Lightweight & Reliabil Technol Engn Vehic, Changsha, Hunan, Peoples R China.;[Hou, Hua] North Univ China, Coll Mat Sci & Engn, Taiyuan 030051, Shanxi, Peoples R China.;[Guo, Zhanhu] Univ Tennessee, ICL, Dept Chem & Biomol Engn, Knoxville, TN 37996 USA.
通讯机构：
[Shi, Minjie] J;Jiangsu Univ Sci & Technol, Sch Mat Sci & Engn, Zhenjiang 212003, Jiangsu, Peoples R China.
关键词：
energy storage;surface chemistry;transportation
摘要：
Wire-shaped supercapacitors (WSSCs) hold great promise in portable and wearable electronics. Herein, a novel kind of high-performance coaxial WSSCs has been demonstrated and realized by scrolling porous carbon dodecahedrons/Al foil film electrode on vertical FeOOH nanosheets wrapping carbon fiber tows (FeOOH NSs/CFTs) yarn electrode. Remarkably, ionogel is utilized as solid-state electrolyte and exhibits a high thermal/electrochemical stability, which effectively ensures the great reliability and high operating voltage of coaxial WSSCs. Benefiting from the intriguing configuration, the coaxial WSSCs with superior flexibility act as efficient energy storage devices and exhibit low resistance, high volumetric energy density (3.2 mW h/cm(3)), and strong durability (82% after 10,000 cycles). Importantly, the coaxial WSSCs can be effectively recharged by harvesting sustainable wind source and repeatedly supply power to the lamp without a decline of electrochemical performance. Considering the facile fabrication technology with an outstanding performance, this work has paved the way for the integration of sustainable energy harvesting and wearable energy storage units.
摘要：
The study reported was intended to improve the leaching rate of boron-bearing tailings, using a method of sodium roasting that uses boron-bearing tailings as the raw material and Na2CO3 as the sodium agent. The effects of the roasting temperature and Na2CO3 amount on the leaching rate of boron-bearing tailings are mainly evaluated. The morphology and composition of the samples after sodium roasting are analysed by scanning electron microscopy and X-ray diffraction. The results show that sodium roasting can significantly improve the leaching rate of boron-bearing tailings. Under the optimal conditions where roasting temperature is 950°C, Na2CO3 amount is five times the theoretical amount and roasting time is 2 h, the leaching rate of boron-bearing tailings is up to 86.78%. Based on the analysis of the characterization results and the mechanism analysis of the sodium roasting process, the main reason for the increase of leaching rate is the reaction between Na2O produced by the decomposition of Na2CO3 and the boron in boron-bearing tailings resulting in soluble sodium borate. The results provide a scientific basis for the efficient comprehensive use of boron-bearing tailings.
摘要：
To prepare a new kind of electromagnetic wave absorber, and improve the processing technology and accessional value of natural microcrystalline graphite minerals (NMGMs), reduced microcrystalline graphene oxide (rGO-M), a novel absorber with high absorption, low reflection and a wide absorption band, was prepared from NMGMs using a solvent-assisted thermal reduction method. Moreover, the as-produced rGO-M with adjustable electrical resistivity can be easily transferred into well distributed bulk materials by freeze-drying technology. These unique structures and compositions make a great contribution to the impedance match, and cause strong conductive loss and various dipole polarization effects which greatly enhance the absorption. Meanwhile, the effective bandwidths below −5 dB and −10 dB are 11.7 GHz and 3.32 GHz respectively, and the reflection loss can reach −42.68 dB. The study will be beneficial to the development of carbon resources and carbon materials research. Besides, it can provide a scientific basis for the further improvement of the comprehensive utilization and the level of deep processing technology of NMGM resources.
摘要：
C/C-SiC composites were fabricated via Si-Zr reactive alloyed melt infiltration using various C/C preforms with different porosities as reinforcements. The influence of preform porosities on the microstructure, mechanical strength and ablation resistance of the as-prepared composites were investigated. The results indicated that microstructure and properties of the C/C-SiC composites seriously depended on C/C preform porosities. The composites were mainly composed of carbon, SiC and ZrSi2 phases, while some residual silicon still existed in the composites prepared with very large porosity preforms. Flexural strength of the composites firstly increased with increasing C/C preform porosities, then reached the highest value, 307 MPa, and finally turned to decrease with the further increasing of preform porosities. Densities of the composites increased with increasing preform porosities, while open porosities were generally small below 7%. Linear ablation rates of the composites firstly sharply decreased with increasing preform porosities and then slightly decreased to reach a balance value. In a word, C/C preform porosity was of great significance for reactive melt infiltration of C/C-SiC composites. Densities, microstructure, mechanical strength and ablation resistance of the resulting composites should be comprehensively taken into consideration to choose an optimal preform porosity for fabrication of C/C-SiC composites.
摘要：
We report a low-cost and effective technique for preparing borax from boron-bearing tailings, which is at a low grade of 9.98% B2O3. Well-crystallized borax is achieved by the removal of impurity, evaporation and concentration through the efficient method of sodium roasting and pressure leaching. The morphology, composition and structure of borax are investigated in this study. The result of scanning electron microscopy shows that the crystals obtained are cube-shaped with smooth surface and of good growth. The crystals are proven to be Na2B4O7·10H2O by EDS, XPS, XRD and ICP-AES. Moreover, the recovery rate of boron can reach 63.49%. This cost-effective strategy of preparing borax from boron-bearing tailings provides a guideline for the development of the boron industry and has a great potential for the commercialization of borax production.
摘要：
Based on the Maxwell equation, the electromagnetic model in the coaxial fiber was described. The interaction with electromagnetic wave was analysed and the theoretical formula of axial permeability (mu(parallel to)), axial permittivity (epsilon(parallel to)), radial permeability (mu(perpendicular to)) and radial permittivity (epsilon(perpendicular to)) of Fe-C coaxial fiber were derived, and the demagnetization factor (N) of fibrous material was revised. Calculation results indicate that the composite fiber has stronger anisotropy and better EM dissipation performance than the hollow carbon fiber and solid iron fiber with the same volume content. These properties can be enhanced through increasing aspect ratio and carbon content. The mu(parallel to) is 5.18-4.46i, mu(perpendicular to) is 2.58-0.50i, epsilon(parallel to) is 7.63-6.97i, and epsilon(perpendicular to) is 1.98-0.15i when the electromagnetic wave frequency is 5 GHz with the outer diameter of 0.866 lm, inner diameter of 0.500 mu m, and length of 20 mu m. The maximum of the imaginary part of mu(parallel to) and epsilon(parallel to) are much larger than that of mu(perpendicular to) and epsilon(perpendicular to) when the structural parameters change, and the maximum of mu(parallel to) and epsilon(parallel to) can reach 6.429 and 23.59. Simulation results show that greater conductivity, larger aspect ratio, thin iron shell play important roles to improve the electromagnetic matching ability and microwave attenuation for the Fe-C coaxial fibers. (C) 2017 Elsevier B.V. All rights reserved.
摘要：
It is a challenge to prepare graphene-like nanosheets (GNs) with desired electrical properties from natural microcrystalline graphite minerals (NMGM) since the impurities in NMGM are always hard to eliminate and the grain size of NMGM is much smaller than that of flake graphite (FG). The morphology, structure, surface chemistry, and compositions of the GNs prepared from NMGM using a liquid oxidation–reduction approach were investigated in this study. GNs with layer number ranging from 3 to 7, thickness of 1.1 nm, and sizes up to 1 μm × 2 μm were obtained and confirmed from scanning electron microscopy, transmission electron microscopy and atomic force microscopy images. The results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis show that, during the whole fabrication process, the generation and elimination of oxygen-containing groups or reestablishment of the conjugated graphene network occur. The results of Raman spectroscopy and X-ray diffraction measurements show that the GNs possess an amorphous nanostructure. The as-produced GNs with adjustable electrical resistivity can be easily transferred into well distributed bulk materials by freeze-dried strategy. This cost-effective synthesis strategy of GNs from abundant NMGM provides great potential for the commercialization of GN production.
关键词：
Microwave absorbing materials;Milling;Natural microcrystalline graphite;Purification;Reflection loss
摘要：
An effective composite of natural microcrystalline graphite/low density polyethylene (MG/LDPE) was prepared by extrusion calendering method and the electromagnetic absorption properties of the composites were investigated. The morphology and structure of the MG were characterized by scanning electron microscopy, energy-dispersive X-ray microanalysis system, Raman spectroscopy and X-ray diffraction. It is interesting to find that two absorbing peaks appear at low frequency and high frequency with the thickness of 2.0–2.1 mm. Results show that the content and the particle size of MG have great effects on the electromagnetic absorption property of the MG/LDPE composites. Under the condition that the speed of ball-milling is 800 r/min, the bandwidth of MG/LDPE composites less than − 5 dB reaches 6.79 GHz, its less than − 10 dB comes to 3.02 GHz, and the reflectivity values are − 12.44 dB and − 20.46 dB. The remarkable electromagnetic absorption properties of MG/LDPE composite can attribute to the multiple absorbing mechanisms. It is believed that such a composite could serve as an attractive candidate for electromagnetic absorbers.
作者机构：
[谢炜; 邹诚茜; 邓应军] Hunan Province Key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle, Changsha University of Science and Technology, Changsha;410114, China;[唐镇宇; 匡加才] Key Laboratory of Lightweight and Reliability Technology for Engineering Vehicle, The Education Department of Hunan Province, Changsha University of Science and Technology, Changsha;[符寒光] College of Materials Science and Engineering, Beijing University of Technology, Beijing;100124, China
