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991.
992.
993.
Gaoyong Lin Yuyong Wei Ke Zhou Hongyang Wang Weiyuan Song 《Materials and Manufacturing Processes》2018,33(2):232-238
AZ80 hollow profile was produced by porthole-die extrusion. The mechanical behavior and microstructure characteristic of extrusion welds in AZ80 hollow profile during different T5 heat treatments were investigated. Five kinds of morphologies of β-Mg17Al12 were observed in turn in weld regions under various temperatures. Extrusion weld is not weakest region in AZ80 hollow profile in terms of hardness, the peak hardness of weld regions is roughly equal to the weld-free regions at different aging temperatures, which is attributed to similar volume fraction, morphology, and size of β-Mg17Al12 precipitate in weld regions and weld-free regions. The precipitate-free zones (PFZs) usually form near the welds interface in aging process, and the hardness of PFZs is usually lower than those of weld regions and weld-free regions. Aging at 200°C for 24?h is suitable heat treatment system for AZ80 hollow profile, which can achieve excellent mechanical property and simultaneously reduce the width of PFZs. 相似文献
994.
Z. Lin E. Goikolea A. Balducci K. Naoi P.L. Taberna M. Salanne G. Yushin P. Simon 《Materials Today》2018,21(4):419-436
Supercapacitors, also known as electrochemical capacitors, have witnessed a fast evolution in the recent years, but challenges remain. This review covers the fundamentals and state-of-the-art developments of supercapacitors. Conventional and novel electrode materials, including high surface area porous carbons for electrical double layer capacitors (EDLCs) and transition metal oxides, carbides, nitrides and their various nanocomposites for pseudocapacitors – are described. Latest characterization techniques help to better understand the charge storage mechanisms in such supercapacitors and recognize their current limitations, while recently proposed synthesis approaches enable various breakthroughs in this field. 相似文献
995.
Hongliang Jiang Yunxiang Lin Bingxu Chen Youkui Zhang Hengjie Liu Xuezhi Duan De Chen Li Song 《Materials Today》2018,21(6):602-610
Realizing large-scale electrochemical hydrogen evolution in alkaline and neutral media by robust and non-noble-metal heterogeneous catalysts is highly ambitious due to the sluggish reaction kinetics at low H+ conditions. Herein, highly efficient hydrogen evolution reaction (HER) catalysts, comprising Ni, NiO clusters, and defective carbon, are successfully constructed via a facile and large-scale route. Multiple synchrotron radiation-based X-ray spectroscopic characterizations, combining high-resolution transmission electron microscopy measurements, indicate the formation of ternary interfacial superstructure with intimate interfacial coupling through abundant NiOC bonds. Impressively, the optimized catalyst loaded onto the usual glass carbon electrode exhibits exceptional catalytic activities with overpotentials of 64 and 76?mV to reach 10?mA?cm?2 in 1?M KOH and 1?M phosphate buffer solution (PBS), respectively, representing one of the best non-noble-metal HER electrocatalysts to date. Insights into the metal/oxide interfacial effects through density functional theory calculations reveal that the interface sites could efficiently lower the energy barrier of the rate-determining step (RDS), contributing to the fast reaction kinetics. This work not only provides comprehensive insights into interfacial feature of highly active HER catalysts but also broadens the fundamental understanding of interfacial effects toward HER catalysis. 相似文献
996.
Soft electronic systems are emerging that are heralded to bring revolution and a frontier for the interactions between human beings and machines. Interactive interfaces enable integrated bidirectional functionalities of sensing the external stimulus and providing interactive response to the users. Human body is considerably soft and stretchable; this characteristic puts forward the need for good mechanical conformabilities for the interfacing electronic devices. As a vital and indispensable component in electronic systems, soft and deformable conductor is of great importance to establish the enabling technologies. Significant progresses have been developed with new strategies and materials being exploited to improve the performance of elastic conductors. In this article, we review the latest advances in deformable conductors and their applications to enable soft electronic devices for human–machine interfaces. We first focus on the important characteristics of the deformable conductors in their stretchability, conductivity, and transparency. Representative soft electronic systems that are categorized into “receptive devices” and “responsive devices” are then reviewed. 相似文献
997.
Nucleation Crystallography of Ni Grains on CrFeNb Inoculants Investigated by Edge‐to‐Edge Matching Model in an IN718 Superalloy 下载免费PDF全文
Wenchao Yang Pengfei Qu Lin Liu Ziqi Jie Taiwen Huang Feng Wang Jun Zhang 《Advanced Engineering Materials》2018,20(2)
998.
Nan Sun Quan‐Ping Zhang Hao‐Ran Sun Wen‐Bin Yang Yuan‐Lin Zhou Jiang‐Feng Song De‐Li Luo 《Advanced Engineering Materials》2018,20(2)
999.
ZIF‐8/ZIF‐67‐Derived Co‐Nx‐Embedded 1D Porous Carbon Nanofibers with Graphitic Carbon‐Encased Co Nanoparticles as an Efficient Bifunctional Electrocatalyst 下载免费PDF全文
Wenming Zhang Xiuyun Yao Shengnan Zhou Xiaowei Li Ling Li Ze Yu Lin Gu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(24)
Herein, an approach is reported for fabrication of Co‐Nx‐embedded 1D porous carbon nanofibers (CNFs) with graphitic carbon‐encased Co nanoparticles originated from metal–organic frameworks (MOFs), which is further explored as a bifunctional electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Electrochemical results reveal that the electrocatalyst prepared by pyrolysis at 1000 °C (CoNC‐CNF‐1000) exhibits excellent catalytic activity toward ORR that favors the four‐electron ORR process and outstanding long‐term stability with 86% current retention after 40 000 s. Meanwhile, it also shows superior electrocatalytic activity toward OER, reaching a lower potential of 1.68 V at 10 mA cm?2 and a potential gap of 0.88 V between the OER potential (at 10 mA cm?2) and the ORR half‐wave potential. The ORR and OER performance of CoNC‐CNF‐1000 have outperformed commercial Pt/C and most nonprecious‐metal catalysts reported to date. The remarkable ORR and OER catalytic performance can be mainly attributable to the unique 1D structure, such as higher graphitization degree beneficial for electronic mobility, hierarchical porosity facilitating the mass transport, and highly dispersed CoNxC active sites functionalized carbon framework. This strategy will shed light on the development of other MOF‐based carbon nanofibers for energy storage and electrochemical devices. 相似文献
1000.
The Influence of Carbon Nitride Nanosheets Doping on the Crystalline Formation of MIL‐88B(Fe) and the Photocatalytic Activities 下载免费PDF全文
Zhen‐Dong Lei Yuan‐Cheng Xue Wen‐Qian Chen Lin Li Wen‐Hui Qiu Yong Zhang Liang Tang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(35)
In this research, bulk graphitic carbon nitride (g‐C3N4) is exfoliated and transferred to the carbon nitride nanosheets (CNNSs), which are then coupled with MIL‐88B(Fe) to form the hybrid. From the results of the powder X‐ray diffraction, scanning electronic microscopy and thermogravimetric analysis, it is found that the doping of CNNSs on the surface of MIL‐88(Fe) could maintain the basic structure of MIL‐88B(Fe), and the smaller dimension of CNNSs might influence the crystallization process of metal‐organic frameworks (MOFs) compared to bulk g‐C3N4. Besides, the effects of the CNNSs incorporation on photocatalysis are also investigated. Through the photoluminescence spectra, electrochemical measurements, and photocatalytic experiments, the hybrid containing 6% CNNSs is certified to possess the highest catalytic activity to degrade methylene blue and reduce Cr(VI) under visible light. The improvement of the photocatalytic performance can be attributed to the matched energy level which favors the formation of the heterojunctions. Besides, it promotes the charge migration such that the contact between MOFs and CNNSs is more intimate, which can be inferred from the electronic microscopy images. Finally, a possible photocatalytic mechanism is put forward by the relative calculation and the employment of the scavengers to trap the active species. 相似文献