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131.
LaCoO3 perovskite was prepared at 700°C using citrate precursors. The product was then characterized with X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). The powder XRD pattern indicates rhombohedral or its monoclinic I2/a subgroup symmetry. The electronic configuration and the short-range atomic structure of the LaCoO3 perovskite at room temperature were investigated using synchrotron near-edge X-ray absorption spectroscopy (XANES) and extended X-ray absorption spectroscopy (EXAFS). From the XANES region of the XAS we conclude that Co(III) is at least partly in its intermediate- or high-spin state, which is in accordance with most of the published literature on LaCoO3 perovskite. The EXAFS region of the LaCoO3 perovskite spectrum, which up to now was almost not investigated, was simulated satisfactorily for the first two radial structure peaks in terms of the dominant scattering contributions generated with the FEFF8 code and the structural information available from crystallographic data. The best simulation results were obtained with I2/a symmetry. The obtained amplitude reduction factor, zero-energy shift and Debye-Waller factors are useful reference values for data analyses of similar compounds like partly substituted LaCoO3 perovskite, such as La1−xCaxCoO3 or La1−xSrxCoO3, which are materials of technical interest in catalyst and other applications. 相似文献
132.
133.
Yu Cheng Xinnan Xu Mengfan Wang Chengwei Deng Yi Sun Chenglin Yan Tao Qian 《Advanced functional materials》2023,33(44):2302332
As a promising energy carrier, ammonia synthesis by electrocatalytic nitrogen reduction reaction (eNRR) is a promising green and low-carbon ammonia synthesis strategy that can replace the traditional Haber–Bosch process. However, the development of eNRR processes is mainly severely constrained by competitive hydrogen evolution reaction (HER), and the corresponding strategies to inhibit this adverse side reaction to obtain high eNRR selectivity are still limited. In addition, for this complex reaction involving gas–liquid–solid three-phase interface and proton/electron transfer, it is great significance to analyze and summarize the existing inhibition HER strategies from the viewpoint of dynamics. In view of this, this work reviews proton supply/filtration regulation strategy in catalytic system, allowing a systematic survey of the literature focusing on interface membrane regulation (inorganic membrane and organic membrane), electrolyte regulation (metal-mediated strategy and electrolyte ion regulation strategy) and system device design (electrode structure design and electrolytic cell device design). Constructive catalytic system design guidance is also suggested to inhibit hydrogen evolution and improve NH3 selectivity, aiming for scalable and economically feasible applications. 相似文献
134.
Internet of Things (IoT) is a newly emerged paradigm where multiple embedded devices, known as things, are connected via the Internet to collect, share, and analyze data from the environment. In order to overcome the limited storage and processing capacity constraint of IoT devices, it is now possible to integrate them with cloud servers as large resource pools. Such integration, though bringing applicability of IoT in many domains, raises concerns regarding the authentication of these devices while establishing secure communications to cloud servers. Recently, Kumari et al proposed an authentication scheme based on elliptic curve cryptography (ECC) for IoT and cloud servers and claimed that it satisfies all security requirements and is secure against various attacks. In this paper, we first prove that the scheme of Kumari et al is susceptible to various attacks, including the replay attack and stolen-verifier attack. We then propose a lightweight authentication protocol for secure communication of IoT embedded devices and cloud servers. The proposed scheme is proved to provide essential security requirements such as mutual authentication, device anonymity, and perfect forward secrecy and is robust against security attacks. We also formally verify the security of the proposed protocol using BAN logic and also the Scyther tool. We also evaluate the computation and communication costs of the proposed scheme and demonstrate that the proposed scheme incurs minimum computation and communication overhead, compared to related schemes, making it suitable for IoT environments with low processing and storage capacity. 相似文献
135.
Ping Cai Ling Ding Ziming Chen Dianhui Wang Hongliang Peng Changlai Yuan Chaohao Hu Lixian Sun Yuriy N. Luponosov Fei Huang Qifan Xue 《Advanced functional materials》2023,33(30):2300113
2D Ti3C2Tx MXene, possessing facile preparation, high electrical conductivity, flexibility, and solution processability, shows good application potential for enhancing device performance of perovskite solar cells (PVSCs). In this study, tetrabutylammonium bromide functionalized Ti3C2Tx (TBAB-Ti3C2Tx) is developed as cathode buffer layer (CBL) to regulate the PCBM/Ag cathode interfacial property for the first time. By virtue of the charge transfer from TBAB to Ti3C2Tx demonstrated by electron paramagnetic resonance and density functional theory, the TBAB-Ti3C2Tx CBL with high electrical conductivity exhibits significantly reduced work function of 3.9 eV, which enables optimization of energy level alignment and enhancement of charge extraction. Moreover, the TBAB-Ti3C2Tx CBL can effectively inhibit the migration of iodine ions from perovskite layer to Ag cathode, which synergistically suppresses defect states and reduce charge recombination. Consequently, utilizing MAPbI3 perovskite without post-treatment, the TBAB-Ti3C2Tx based device exhibits a dramatically improved power conversion efficiency of 21.65% with significantly improved operational stability, which is one of the best efficiencies reported for the devices based on MAPbI3/PCBM with different CBLs. These results indicate that TBAB-Ti3C2Tx shall be a promising CBL for high-performance inverted PVSCs and inspire the further applications of quaternary ammonium functionalized MXenes in PVSCs. 相似文献
136.
137.
碳化硅(SiC)器件的新特性和移动应用的功率密度要求给功率器件的封装技术提出了新的挑战。现有功率器件的封装技术主要是在硅基的绝缘栅双极晶体管(Insulated Gate Bipolar Transistor,IGBT)和金属氧化物半导体场效应晶体管(Metal Oxide Semiconductor Field Effect Transistor,MOSFET)等基础上发展起来的,并一直都在演进,但这些渐进改良尚不足以充分发挥SiC器件的性能,因而封装技术需要革命性的进步。在简述现有封装技术及其演进的基础上,主要从功率模块的角度讨论了封装技术的发展方向。同时讨论了功率模块的新型叠层结构以及封装技术的离散化、高温化趋势,并对SiC器件封装技术的发展方向做出了综合评估。 相似文献
138.
针对某双列直插式(DIP)封装器件在整机温循试验中出现的失效现象,分析在器件与电路板焊接环节、电路板与整机装配环节和整机温循试验环节3个工况下可能的失效原因,对原因分别进行单工况和多工况的失效仿真分析。针对不同仿真模型在不同工况下的叠加仿真难题,提出基于ANSYS Workbench有限元软件的多应力叠加仿真方法,对比单一工况和多种工况下的仿真结果。结果表明,DIP封装器件失效是器件在焊接尺寸不匹配、过定位装配和温循试验三种工况下,机械应力和热应力的叠加使玻璃绝缘子产生裂纹导致的,有限元仿真结果与实验结果基本吻合,为DIP封装器件在多工况下应力叠加失效的故障机理研究提供一种可参考的仿真方法。 相似文献
139.
140.
《Electroanalysis》2003,15(13):1109-1114
The electrochemical characterization of a hydrogen peroxide sensor based on a ferrocene‐containing polymer electrochemically deposited onto a platinum electrode is described. The redox polymer consists of a siloxane‐based homopolymer, with pendant electronically communicated ferrocenyl moieties. The electrodes were used as the transducer for glucose and lactate‐sensing enzyme sensors. Amperometric biosensors were prepared by immobilization of glucose oxidase (Gox) or lactate oxidase (Lox) onto these modified electrodes. The steady‐state amperometric response of the sensors is investigated as a function of the applied potential and substrate concentration. Interferences, sensitivity and stability of the sensors were also studied. 相似文献