Experimental investigation on the performance and durability of hydrogen AEMFC with electrochemical impedance spectroscopy

In situ experimental tests and scanning electron microscope (SEM) observations are done to explore the impact of geometry structure and operating conditions on the performance and durability of alkaline electrolyte membrane fuel cell (AEMFC) accompanied by electrochemical diagnosis. The results show that low anode and cathode polarization resistances can be achieved by selecting a proper ionomer mass fraction (IMF) of the catalyst layer (CL). Increasing the IMF can improve the tolerance to inlet gas humidity. The presence of the anode microporous layer (MPL) greatly improves the cell performance, but cathode MPL plays a reverse effect. After the durability test, the homogeneity of CL is seriously deformed, leading to a great increment of anode and cathode polarization resistances, verified by the electrochemical impedance spectroscopy (EIS) and SEM results. An enhancement of fuel cell durability is achieved by adding nanoscale polytetrafluoroethylene (PTFE) into CL. This work can provide some guidance for the structural and operating parameter optimization of the AEMFC researches in the future.     

Electron microscope investigation on hydrogen storage materials: A review

Hydrogen energy is a highly efficient and renewable energy carrier. The rapid and sophisticated development of nanotechnologies has promoted the transition of hydrogen storage systems from gaseous/liquid to solid-state. In order to clarify the intrinsic relationship between structure and performance, and to understand the hydrogen absorption and desorption mechanism of materials, electron microscopy (EM) can effectively help us obtain a series of information such as particle size, phase and composition determination, morphology and structure of the materials at nanoscale. The most recent progress of advanced EM techniques applied in solid-state hydrogen storage materials are summarized, which should also inspire future research on energy storage related materials.     

加福煤粉燃烧过程的微观形态观察

应用光学显微镜和扫描电子显微对加福煤粉燃烧过程中微观形态的变化规律进行了详细的观察。研究结果表明,加福煤粉燃烧过程中出现白球,棕色球,黑球,黑块Ⅰ,黑块Ⅱ这五种形态各异的颗粒,热力工况对其燃尽过程有影响,降低飞灰含碳量关键在于设示将黑块Ⅰ完全燃烧,使黑块Ⅱ尽可能地着火燃烧。     

SnO2 as thin conformal layer over BiVO4 surface for enhanced charge carrier separation towards O2 evolution from water oxidation

Recently, bismuth vanadate (BiVO₄) has attracted substantial attention for photocatalytic applications owing to its many advantages as semiconductor to drive water oxidation. Despite possessing promising characteristics to be applied in photocatalysis, the fast electron-hole pairs recombination is still one of the drawbacks involving this semiconductor. The use of conformal layers to minimize such limitation and to improve charge separation is the aim of this work. Herein, we report on the use of SnO₂ as a conformal coating layer over the BiVO₄ surface for O₂ evolution reaction. The incorporation of SnO₂ over the BiVO₄ surface showed the beneficial effect in O₂ evolution compared to the pristine material, resulting in 490 μmol after 6 h of irradiation. Transient absorption and surface photovoltage spectroscopies indicate enhanced charge carrier separation and transport by passivating BiVO₄ with SnO₂ thin layer. Even though the O₂ evolution tests in this work were carried out without the presence of a co-catalyst, the use of a thin conformal coating of SnO₂ over BiVO₄ showed promising results for further studies.     

The structural ordering of thin silicon films at the amorphous to nano-crystalline phase transition by GISAXS and Raman spectroscopy

Thin silicon films were deposited by the plasma-enhanced chemical vapour deposition method using microwave (MW) and standard radio frequency (RF) gas discharge in silane gas diluted by hydrogen in the range that produces a mixture of amorphous and crystalline phases. The samples were analysed by Raman spectroscopy and grazing incidence small-angle X-ray scattering (GISAXS), while the threshold for the transition between the amorphous and crystalline phase was checked by the change in electrical conductivity. The crystalline fraction, estimated by Raman spectroscopy, varied between 0% and 70% while the individual crystal sizes were between 3 and 9 nm. However, the size distribution was broad suggesting also the existence of smaller and larger crystals.The “particles” observed by GISAXS, most probably voids, were in the range between 2 and 12 nm. The voids in samples deposited by MW plasma were larger when closer to the surface. Their shape indicated the formation of a columnar structure perpendicular to the surface, more pronounced at higher temperature. The samples deposited by RF plasma and low power had spherically symmetric “particles” with uniform size across the depth of the samples. An increase of the RF power resulted in the formation of a columnar structure parallel to the surface. The observed differences are discussed in relation to the difference in growing kinetics of the used deposition methods.     

浅谈三维扫描进行锅炉产品预组装仿真可行性

本文通过对电站锅炉产品预组装工序存在的难点进行简单介绍,浅谈将三维扫描、仿真技术应用在电站锅炉产品预组装工序中的可行性,从而改变现有生产方式,提高预组装准确度和生产效率.     

Scanning Probe Microscopy for Thermal Transport Measurements

Understanding energy transport and dissipation in nanoscale devices is of increasing importance. Novel transport and dissipation phenomena are expected to arise in these devices as the characteristic dimensions become comparable to the wavelength, coherence length, and mean free path (MFP) of charge and energy carriers—electrons and phonons. Of particular importance are irreversible processes that occur in all nanoscale devices under nonequilibrium conditions and are associated with Joule heating and resultant temperature gradients. Therefore, the ability to measure local temperatures with nanometer resolution is critical for characterizing and understanding irreversibility, heat dissipation, and transport in nanoscale devices. A novel approach for high-resolution characterization of temperature fields is scanning thermal microscopy (SThM), which leverages special scanning probes with integrated temperature sensors. This review discusses various SThM techniques and highlights recent advances in ultra-high-vacuum SThM techniques for quantitative nanoscale thermometry. Further, we discuss applications of SThM to the elucidation of energy transport and dissipation in functional devices as well as prototypical low-dimensional devices.     

Synthesis and characterization of ceria based nanometric powders

Nanopowdered solid solution Ce_1−xFe_xO_2−δ samples (0 ≤ x ≤ 0.1) were synthesized by a self-propagating room temperature synthesis (SPRT). XRD and Raman spectroscopy at room temperature were used to study the vibrational properties of these materials as well as the Fe solubility in ceria lattice. Results show that all obtained powders are solid solutions with a fluorite-type crystal structure and all powders were nanometric in size. The average size of Ce_1−xFe_xO_2−δ particles lies about 5 nm. The results of electrical properties of the sintered samples investigated by an ac impedance spectroscopy are also presented and discussed. It was confirmed that Fe³⁺ doped ceria material has a potential as electrolyte for intermediate-temperature solid oxide fuel cell applications.     

Scanning tunneling microscopy of electrodeposited CuInSe2 nanoscale multilayers

We have investigated the electrochemical deposition of modulated thin films based on the Cu_xIn_2−xSe₂ system. CuInSe₂ is a leading alternative to silicon for use in thin film photovoltaic solar cells due to its optical absorption and electrical characteristics. Alternating layers of two different compositions based on the Cu_xIn_2−xSe₂ system were potentiostatically deposited. These nanometer-scale layers are used to form reduced-dimensionality structures such as superlattices that can be used in concentrator solar cells. We have used X-ray diffraction, energy-dispersive spectroscopy, and scanning tunneling microscopy to characterize our asdeposited thin films. The ability of the scanning tunneling microscope to resolve the individual nanoscale layers of our multilayered thin films is shown and is used to determine modulation wavelengths.     

柱塞式压力扫描阀在压气机试验中的应用

本文介绍了用于全台压气机试验的8301型柱塞式压力扫描阀的结构、工作原理及其作为MDR-Z80微机数据自动采集系统的压力测量子系统的构成,对工作程序和测量数据的精度进行了分析。该系统全部联机实行集中控制,自动化程度高、造价低、容量大,抗干扰力强是各类压力测量的良好手段。     

Study of glasses/glass-ceramics in the SrO-ZnO-SiO2 system as high temperature sealant for SOFC applications

Glasses having composition (in wt.%) 51SrO-9ZnO-(40−x)SiO₂ (SZS), where x represents the additives like B₂O₃, Al₂O₃, V₂O₅, and Cr₂O₃, were prepared by melt-quench method and transformed into glass-ceramics by controlled crystallization based on differential thermal analysis (DTA) data. Glasses and glass-ceramics were characterized using dilatometry, X-ray diffraction (XRD), microhardness, and Raman spectroscopy. XRD revealed that glass-ceramics are composed of mainly Sr₂ZnSi₂O₇ and SrSiO₃ crystalline phases along with residual glassy phase. Raman spectroscopy showed that main constitutes of the glass network are the Q¹ and Q² silicate structural units. With the addition of B₂O₃ and other additives silicate glass network depolymerizes and concentration of Q¹ structural units increases at the expense of Q² units. Formation of phases during crystallization depends on the presence of different silicate structural units in the glass matrix. B₂O₃ goes into the glass network as triangular (BO₃) borate structural units and at higher concentration of B₂O₃, only a part of the B₂O₃ forms tetragonal (BO₄) structural units. Investigated glasses and glass-ceramics have thermal expansion coefficient (TEC) in the range of 105-120 × 10⁻⁷/°C which matches with TEC of other cell components. B₂O₃ containing SZS glasses show good adhesion/bonding with YSZ and Crofer 22 APU. Elemental line scans indicate that interdiffusion of Fe, Cr and Si across interface is responsible for good bonding with Crofer 22 APU and interdiffusion of Sr, Si, Y and Zr is responsible for good bonding with YSZ.     

Raman spectroscopy of SrZrO3 based proton conducting electrolyte: Effect of Y-doping and Sr-nonstoichiometry

The present research describes the results of Raman spectroscopic study of undoped and Y-doped SrZrO₃ having a great potential for application in proton-conducting fuel cells. Effects of yttrium doping and strontium nonstoichiometry on the local environment of cations and vibrational properties of strontium zirconate were investigated. Ceramic samples Sr_yZr_1-xY_xO_3-δ (x = 0, 0.02, 0.05; y = 0.94, 0.98, 1.00) were synthesized via a chemical solution method and sintered at 1650 °C. Microstructure, phase and chemical composition of the samples were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Analysis of Raman spectra peculiarities upon changes in Sr- and Y- concentrations has shown that yttrium ions can be partitioned over both A- and B-sites in the strontium-deficient zirconates with the dopant concentrations more than 2 at%.     

Iodine speciation studies on Bunsen reaction of S–I cycle using spectroscopic techniques

Bunsen reaction is an important step of sulfur–iodine cycle for hydrogen production from thermochemical splitting of water. Polyiodide species generated during the separation process need to be identified for complete understanding of the mechanism involved. Speciation of these polyiodide species formed during Bunsen reaction can lead to better understanding of kinetics of the process. HIx species formed have been analyzed using UV–visible and Raman spectroscopic techniques. Peak corresponding to HI₃ species have been ascertained and their conversion to higher HI₅, HI₇ …… species has been observed.     

Electrical and spectroscopic characterisation of nanocrystalline V/Ce oxides

Mixed vanadium oxide/CeO₂ films and powders prepared via inorganic sol-gel route were characterized using impedance spectroscopy, grazing-incidence small angle X-ray scattering (GISAXS) and Infrared and Raman spectroscopies. Variation of film resistivity with composition is related to variation of porosity. Grain sizes obtained by GISAXS are compared with the values previously obtained by AFM and XRD. The structure of V/Ce mixed oxides is studied using Infrared and Raman spectroscopies and the results, especially characterization of amorphous phase, are compared with the previously published results obtained using X-ray spectroscopy.     

Comparison of the surface changes on cathode during long term storage testing of high energy density cylindrical lithium-ion cells

Nickel-based oxide cathode material taking out from lithium-ion cell after storage for 2 years at 45 °C is analyzed by electron energy-loss spectroscopy in a scanning transmission electron microscope (STEM-EELS) and the result of STEM-EELS is compared with cobalt-based oxide cathode material which is treated as same manor as nickel-based oxide cathode material. The Ni-L_2,3 energy-loss near-edge structure (ELNES) spectra of nickel-based oxide cathode material show peak positions similar to original material before storage. This result indicates that nickel-based oxide material has no significant change in the surface structure. On the other hand, a remarkable shift to low energy is observed in the Co-L_2,3 ELNES spectra of the cobalt-based oxide cathode material after storage. The cycle test at 60 °C under the conditions of aggressive driving cycle (US06) mode for the nickel-based oxide cathode/graphite cell is also carried out. It is clear that cycle performance of the nickel-based oxide cathode/graphite cell is dependent on the depth of discharge (DOD).     

三维激光雷达扫描技术在河流模拟中的应用

三维激光雷达扫描技术以精度高、测量速度快的特点被应用于多个行业。为快速获取河道流场结构,开展60°弯道动床模型试验,探索采用激光雷达扫描技术获得河床数字地形,以激光扫描数字地形和水准测量地形为边界开展水流数值模拟,并将模拟值与试验测量值进行对比分析。结果表明,流场数值模拟结果与试验值吻合较好。沙波地形的精度对纵向时均流速、水深平均流速影响有限,但对河床切应力及断面流场结构影响明显。将激光雷达扫描技术和数值模拟技术相结合,既能获得高精度的河床数字高程和精细水流流动结构,又可大大缩短试验流场测量周期。     

Review: Tip-based vibrational spectroscopy for nanoscale analysis of emerging energy materials

Vibrational spectroscopy is one of the key instrumentations that provide non-invasive investigation of structural and chemical composition for both organic and inorganic materials. However, diffraction of light fundamentally limits the spatial resolution of far-field vibrational spectroscopy to roughly half the wavelength. In this article, we thoroughly review the integration of atomic force microscopy (AFM) with vibrational spectroscopy to enable the nanoscale characterization of emerging energy materials, which has not been possible with far-field optical techniques. The discussed methods utilize the AFM tip as a nanoscopic tool to extract spatially resolved electronic or molecular vibrational resonance spectra of a sample illuminated by a visible or infrared (IR) light source. The absorption of light by electrons or individual functional groups within molecules leads to changes in the sample’s thermal response, optical scattering, and atomic force interactions, all of which can be readily probed by an AFM tip. For example, photothermal induced resonance (PTIR) spectroscopy methods measure a sample’s local thermal expansion or temperature rise. Therefore, they use the AFM tip as a thermal detector to directly relate absorbed IR light to the thermal response of a sample. Optical scattering methods based on scanning near-field optical microscopy (SNOM) correlate the spectrum of scattered near-field light with molecular vibrational modes. More recently, photo-induced force microscopy (PiFM) has been developed to measure the change of the optical force gradient due to the light absorption by molecular vibrational resonances using AFM’s superb sensitivity in detecting tip-sample force interactions. Such recent efforts successfully breech the diffraction limit of light to provide nanoscale spatial resolution of vibrational spectroscopy, which will become a critical technique for characterizing novel energy materials.     

基于阻抗谱重构技术的电池健康状态快速估计方法

电池健康状态（state of health,SOH）是保证系统安全稳定运行的关键,健康状态估计不准将影响电池的使用性能,甚至引发电池滥用等问题。电池电化学阻抗谱通过宽频范围内电池的阻抗特征来反映其内部的电化学过程,蕴含了大量电池老化信息,已经逐渐成为分析锂离子电池性能的有力工具。然而,传统的电池阻抗谱测试方法耗时长、成本高昂。为此,以实现锂离子电池的精细化检测与健康状态快速评估为目标,围绕基于电化学阻抗谱重构技术的电池健康状态估计方法展开研究。通过逆重复最大长度序列设计多频电流激励信号,实现了电池阻抗谱的快速测试。采用连续小波变换开展阻抗谱重构,从而获取目标频率范围内的电池阻抗信息,整个过程耗时小于4.5 min。通过不同老化状态电池在特殊频率点下的重构阻抗幅值建立经验模型,实现了电池健康状态的快速准确评估。     

Structural properties of phosphorous-doped polycrystalline silicon

The structural properties and hydrogen bonding of undoped and phosphorous doped polycrystalline silicon produced by step-by-step laser dehydrogenation and crystallization technique were investigated using Raman spectroscopy and hydrogen effusion measurements. At low laser fluences, E_L, a two-layer system is created. This is accompanied by the change in hydrogen bonding. The intensity of the Si–H vibration mode at 2000 decreases faster than the one at 2100 cm⁻¹. This is even more pronounced in phosphorous-doped specimens. The laser crystallization results in an increase of the hydrogen binding energy by approximately 0.2–0.3 eV compared to the amorphous starting materials.     

Synthesis of scalable 1T/2H–MoSe2 nanosheets with a new source of Se in basic media and study of their HER activity

In this report MoSe₂ nanosheets were fabricated using new precursors of MoCl₅ and Na₂SeO₃ and a very simple chemical procedure without using inert atmosphere and complex methods for preparing Se ion source. The structural properties of fabricated nanosheets were examined by means of XRD, field emission scanning electron microscopy (FESEM), elemental mapping of energy dispersive x-ray spectroscopy (EDS), transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman spectroscopy and isotherm gas adsorption-desorption technique. The results showed the nanosheets are mixed phase metallic-semiconductor 1T-2H with thicknesses about 3.6–6.1 nm and are stable for several months. The effective surface area is obtained 28 m² g⁻¹ and mean pore size of 6–8 nm for MoSe₂ nanosheets. Electro-impedance spectroscopy showed low resistivity of nanosheets due to presence of metallic phase of MoSe₂. HER activity of nanosheets obtains a Tafel slope of 60 mV.dec⁻¹ and high current density values up to 150 mA cm⁻² and the value of over potential at 10 mA cm⁻² is 155 mV.