Synchrotron Radiation Research Research Articles

Cryogenic oxygen deficiency hazard assessment at the National Synchrotron Radiation Research Center

The National Synchrotron Radiation Research Center (NSRRC) uses cryogenic fluids to create a low-temperature cooling environment for equipment and to conduct various experiments. However, exposure to these cryogenic fluids can cause frostbite, hypoxic suffocation, behavioral incapacitation, insanity, and even death in severe cases. To evaluate oxygen deficiency hazard (ODH) in the NSRRC, we adopted the Fermilab assessment methodology and conducted ODH assessments in the Cryogenic Compressor Room, Taiwan Light Source (TLS) Tunnel, and TLS15A hutch. The results of the evaluation of the Cryogenic Compressor Room and TLS Tunnel revealed that the ODH class is 0 both when the exhaust fan is operating normally and when the exhaust fan is damaged. The exhaust equipment in the TLS15A hutch is only for emergency use. Without the emergency exhaust fan, the ODH class in the area is 1. If the emergency exhaust fan is always on, the ODH class is 0. Therefore, we recommend that those in TLS15A should undergo safety education and receive hazard notifications. In addition, we strongly recommend installing oxygen detectors in the beamline hutch to ensure safety.

Respiratory protective equipment fit tests for researchers at the national synchrotron radiation research center

Researchers at the National Synchrotron Radiation Research Center should use respiratory protective equipment to prevent respiratory damage caused by gases, steam, solvents, chemicals, materials containing toxic substances, and oxygen-deficient environments. Those working with organic matter and certain chemical substances and those exposed to occupation dust should use respiratory protective gear to ensure their health. This study conducted qualitative and quantitative fit tests for various mask brands and sizes, namely 3M-9042, N95-9211, P95-8576, and 3M-6200 masks. The gear worn by all 18 participants in the qualitative fit test passed. By contrast, the gear worn by 12 of the 15 participants in the quantitative test passed; the failure of the remaining gear was due to differences in face shape. The N95-9211 mask can be used in three-piece protective gear because it exhibited a tight fit. Additionally, the 3M-6200 negative-pressure half-face mask exhibited the most satisfactory fit and can be used in protective gear.

Investigation of Stable Structures and Electronic States of Spinel MgCo2−ZNi0.5MnAlzO4 (z = 0, 0.3) during Discharge Process As Cathode Materials for Magnesium Rechargeable Batteries Using First-Principles Calculations

Introduction Recently, it is focused on storage batteries materials for reduce of greenhouse gases. In particular, the development of large equipment like as electric vehicles is driving demand for storage battery materials. Although lithium-ion batteries are currently used as storage battery devices, Li metal is a rare metal and expensive, and the development of higher capacity battery materials is needed. Our research group is focusing on magnesium secondary battery cathode materials. In previous report, spinel MgCo2-xMnxO4 (x=0~0.5) (space group Fd-3m) has synthesized and evaluated its battery characteristics, showing an initial discharge capacity of more than 200mAh/g when the Mn substitution amount is x=0.5.1) Since the inclusion of substituted species improves battery properties, we synthesized Al substituted spinel MgCo2-zNi0.5MnAlzO4. In this study, we reported that Mg/Co cation mixing, which was particularly problematic at z=0.3 was reduced compared to MgCo2-xMnxO4 resulting in improved cycle properties.2) The purpose of this study is to clarify the stable local structure of pristine and discharge process of spinel type MgCo2-zNi0.5MnAlzO4 (z=0, 0.3) and to determine the contribution of Al substitution to the electronic structure by performing electron density calculation. Calculation The structural relaxation calculation was performed by generalized gradient approximation (GGA) exchange-correlation potential used with a plane-wave cutoff energy of 550 eV, and 1×2×2 k-point mesh was applied, corresponding to the inverses of the lattice constants on Vienna Ab-initio Simulation Package (VASP) code. The convergence criterion for structural optimization was that the energy difference per iteration be less than or equal to 0.02 eV/Å. 2×1×1 supercell was created and structural relaxation calculation was performed on various initial structural models to determine the energetically optimal structure. Initial structure models were constructed to ensure reproduction of the occupancies determined by an average structure analysis from Rietveld analysis using synchrotron X-ray diffraction. Result and discussion In this study, we performed structural relaxation calculations for spinel-type MgCo2-zNi0.5MnAlzO4 (z=0, 0.3) to obtain the stable structure before and during charge-discharge. The initial model before charging and discharging was created based on the occupancy of each site obtained by crystal structure analysis using neutron diffraction measurements.2) The initial model at discharge was obtained by inserting Mg into the 16c vacancy site in the stable structure before charging and discharging. Figure 1 shows the stable structure after structural relaxation calculations before for a-1) z=0 and b-1) z=0.3 and after discharge (y=0.375) for a-2) z=0 and b-2) z=0.3, respectively. The solid circled Mg is the inserted one, and the dotted circle is the 8a site that became vacant after the structural relaxation calculation in Fig. 1. The crystal structure in pristine was spinel structure, however, it is found that the 4-coordinated 8a site became a vacancy and Mg occupied the 16c site, changing the crystal structure to a rocksalt structure after discharge. Since the 8a and 16c site are close to each other, the insertion of Mg into the 16c site causes a structural change due to the repulsion between atoms and cations on the 8a site, which leads to a chain transfer to other vacancy 16c sites. In particular, models with large structural changes tended to have stable structures. It is also found that Mg remained at the 8a site in z=0.3 shown in b-2) than in z=0 shown in a-2), and that Co at the 8a site could not move to the vacancy in z=0, and that the amount of change in the entire structure is less than that in z=0.3. As a result of partial density of states (PDOS) calculation, it is confirmed that Co and Mn had 2.6 ~ 2 valence and Mn is considerably close to 3 valence during discharge. It is also found that the PDOS of Ni did not almost change before and after discharging, and that no valence change occurred. These results are consistent with those of previously reported XANES measurements.2) Therefore, the model in Fig. 1 determined in this study is considered to be valid. Acknowledgement This research was financially supported by JST, ALCA-SPRING Grant Number JPMJAC1301, Japan. This work was also supported in part by JSPS KAKENHI Grant Number 20K15382, Japan. Dr. Koji Ohara of JASRI (Japan Synchrotron Radiation Research Institute for assistance with synchrotron X-ray total scattering measurements (BL04B2, SPring-8, Proposal Nos. 2019B1249).1) Y. Idemoto, M. Ichiyama et al., J. Power Sources, 482 , 228920 1-9 (2021)2) Y. Hirata, Y. Idemoto et al., ECS Meeting s, MA2020-02 , 3451 (2020) Figure 1

In-Situ Observation of Adsorption Species on Platinum Catalyst in Oxygen Reduction Reaction Using High Energy Resolution XAFS

The oxygen reduction reaction (ORR) on Pt surfaces, for examples, Pt single crystals, polycrystalline Pt electrodes, Pt nanoparticles (NPs), Pt-based alloys, and core–shell Pt nanostructures, has been discussed in the last few decades.In polymer electrolyte fuel cells (PEFCs), hydrogen peroxide and its radicals are known to be fatal attacking species not only for electrode catalysts but also for carbon materials and polymer membranes.A thorough understanding of ORR schemes has led to the development of seamless four-electron reduction cathodes, contributing to improved endurance reliability of both anion-exchange membrane (AEM) and proton-exchange membrane (PEM) fuel cells.In this study, the reaction pathway, and intermediate species such as molecular oxygen, in the ORR were investigated in alkaline and acidic environments, respectively.In this work, High Energy Resolution Fluorescence Detection X-ray Absorption Spectroscopy (HERFD-XAS) at the Pt L III-edge, which enhances resolution by partially collecting fluorescent X-ray was employed.X-ray absorption fine structure (XAFS) can detect the electronic structure of Pt, and its high energy resolution makes it possible to distinguish between different adsorption species on the surface of Pt nanoparticles.In addition, photon-in photon-out experiments using hard X-ray with high penetrating ability make it relatively easy to perform in-situ/operando measurements in potential controlled solutions.Carbon-supported Pt nanoparticles as powder catalysts were used for measurement as more realistic conditions, and the species adsorbed on the Pt nanoparticles were analyzed while controlling under the potentials both in acidic and basic electrolyte solutions with N2 or O2 gas bubbling.In N2-saturated solutions, the XANES spectra of the Pt LIII-edge reflected the presence of the adsorption species such as Pt-O (*O), Pt-OH (*OH), Pt-H (*H), as well as PtO2 oxide and Pt metallic states without any adsorption, during the ORR with the potential change.In O2-saturated solutions, one additional adsorption species of molecular oxygen was observed in both acidic and basic electrolyte solutions. It was analyzed that the intermediate species adsorbed to platinum in a side-on configuration as a superoxide anion in an alkaline environment.This intermediate species is identified as hydrogen superoxide, also known as hydroperoxyl radical, with the chemical formula HO2 by being protonated in an acidic environment.The results of research on adsorption species using HERFD-XAS have provided important knowledge for designing catalysts that enable seamless four-electron reduction.The preferred cathode catalyst design will be discussed in detail in an oral presentation at the 244th ECS Meeting. Acknowledgments: The synchrotron radiation experiments were performed at the BL11XU in the SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal Numbers of 2012B3506, 2013A3506, 2014A3506, 2014B3506, 2015B3506, 2016A3556 2019A3508, 2019B3508, 2020A3508, 2021A3508, 2021B3508, 2022A3508 and 2022B3597 at BL11XU). This work was supported by JSPS KAKENHI Grant Number JP22H02188). Figure 1

Ultraviolet spectrum reveals the presence of ozone on Jupiter's moon Callisto

Sulphur dioxide (SO2) is known to be present on Callisto. In this paper, we studied the chemical evolution of SO2 astrochemical ice induced by irradiation using 9 eV (137.7 nm) vacuum ultraviolet light produced from the high-flux beamline of the storage ring at the National Synchrotron Radiation Research Centre in Taiwan. Ultraviolet absorption spectra of the irradiated ice recorded in the 240–320 nm region reveal a broad absorption band indicating the formation of ozone. By comparing these laboratory spectra with Hubble Space Telescope data of the surface of Callisto in this spectral region, we find compelling evidence to consider the presence of ozone on Callisto. Furthermore, there is an additional band peaking at 309 nm whose assignment is as yet unclear but is quite similar to a band observed on Ganymede, thus leading us to suspect a common molecular source.

Observations on Laue diffraction within synchrotron radiation and neutron macromolecular crystallography research and developments.

A seminal contribution in the domain of physiologically relevant biological structure and function determination was by Keith Moffat, of Cornell and latterly of the University of Chicago proposing that synchrotrons should offer the option of a Laue method data collection mode. I enthusiastically joined in supporting this initiative. This proposal needed detailed methods development though; theoretical, experimental and software development. This work was added to the broad research and development program of synchrotron radiation at the UK's SRS. This whole program led to knowledge transfer from the UK's SRS to the ESRF as well as for neutron Laue protein crystallography to the reactor spallation sources and later to spallation neutron sources.

Development of EUV interference lithography for 25 nm line/space patterns

In this study, we present the performance of an extreme ultraviolet interference lithography (EUV-IL) setup that was reconstructed at Taiwan Light Source 21B2 EUV beamline in the National Synchrotron Radiation Research Center (NSRRC), Taiwan. An easy-to-perform fabrication method to produce a high-quality transmission grating mask and a simple design of experimental setup for EUV-IL were developed. The current EUV-IL setup is capable of fabricating line/space patterns down to 25 nm half-pitch in hydrogen silsesquioxane (HSQ) resist. Preliminary exposure results revealed that optimized slit width and exposure time significantly improved line/space pattern quality. The current EUV-IL tool at NSRRC can be used for nano-patterning and resist screening to advance the next generation of semiconductor devices.

Special issue celebrating Professor Yu Wang's 80th birthday

Prof. Yu Wang [the middle of the front row] with friends and colleagues at her 70th birthday symposium and celebration, 2013 It is our great pleasure to organize this special issue of the Journal of the Chinese Chemical Society (JCCS) dedicated to the occasion of Professor Yu Wang's 80th birthday. We do appreciate all authors' great efforts in this special issue. Professor Wang was born in June 1943 and grew up in Hsinchu, Taiwan. She received her bachelor degree in chemistry from National Taiwan University (NTU) in 1966 and her Ph.D. degree from University of Illinois, USA in 1973. After completing her post-doctoral research at State University of New York Buffalo for 1 year and assistant researcher at National Research Council of Canada for 5 years, Professor Wang returned to Taiwan and took up her teaching post as an associate professor at NTU in 1979. She became a full professor in 1981 and served as the Dean of the College of Science from 2002 to 2005. She retired in 2013 as an Emeritus Professor and continued to be active in the community. In addition, she served as the Director General at Department of Math and Physical Science, NSC (1998–2001), and as the Vice President of Academia Sinica, 2014–2016. Professor Wang is a world-renowned scientist for her frontier research on crystallography and chemistry. Several pioneer works have been accomplished during her research career. Two areas are worth mentioning: Charge density studies by combining highly accurate X-ray diffraction data and relevant molecular calculations lead to obtain the insights of chemical bonding and physical properties. This area is expanded now to Quantum Crystallography. The other is her works in spin crossover system, where she accomplished a single crystal to single-crystal spin transition via photo excitation (Photo Crystallography). She has published more than 300 papers. Because of her excellence in research, Professor Wang was awarded as an academician of Academia Sinica in 2010. In addition to her research, she also made a great deal of contributions to both local and international academic communities. She played an important role in the development of local crystallographic society and was instrumental in helping Taiwan become a member of IUCr since 1996. She is reputed as the “Mother of crystallography in Taiwan.” Over the years, she served on several prestigious crystallographic societies: Chairman of Crystallographic Committee, Academia Sinica, Taipei (1995–2003), Commission Member of CSMD, IUCr (1996–2002), the President of Asian Crystallographic Association (AsCA) (2002–2004), and Chairman of CSMD, IUCr (2005–2008). She also served as the Editor-in-Chief of the Journal of Chinese Chemical Society, co-published by Wiley in 2006–2014. In addition to her scientific achievement, Professor Wang is also an excellent educator. She is the most gifted educator I have ever known. She always gives her students the best ever-ending love and enthusiasm. Being her student is our greatest reward. To celebrate Professor Wang's 80th birthday, we dedicate this special issue of the JCCS to her. There are 30 cutting-edge articles in this issue contributed from her former students, colleagues, and friends over the years. We are grateful to all authors who have endeavored to bring about a refreshing novelty in this special issue. Dr. Kuan-Jiuh Lin Chairman and Lifetime Distinguished Professor Department of Chemistry National Chung Hsing University Dr. Hwo-Shuenn Sheu Scientist National Synchrotron Radiation Research Center Dr. Biing-Chiau Tzeng Professor Department of Chemistry and Biochemistry National Chung Cheng University

The highly efficient protein crystallography beamline TLS 13B1 at the National Synchrotron Radiation Research Center

AbstractSynchrotron protein crystallography (PX) is one of the most powerful and dominant tools for determining the three‐dimensional structures of biological macromolecules. At the National Synchrotron Radiation Research Center, TLS 13B1 is the first dedicated energy‐tunable and highly automated PX beamline for efficiently solving de novo protein structures in Taiwan and has been open for users since September 2005. With remote access, user support services, and annual PX training courses over 17 years, the number of user groups at TLS 13B1 has grown from 11 to 139. In total, 1,429 projects were supported, and 2090 experiments were hosted during 67,846 hr of beamtime. This paper describes the photon source, beamline components, experimental station equipment, beamline software, beamline application process, and results from our users.

高圧スライド法を用いたTi同素変態のその場放射光X線解析

In this study, severe plastic deformation through high-pressure sliding (HPS) was applied for in situ high-energy X-ray diffraction analysis at SPring-8 in JASRI (Japan Synchrotron Radiation Research Institute). Allotropic transformation of pure Ti was examined in terms of temperatures, pressures and imposed strain using a miniaturized HPS facility. The true pressure applied on the sample was estimated from the peak shift. Peak broadening due to local variation of pressure was reduced using white X-ray. The phase transformation from α phase to ω phase occurred at a pressure of ∼4.5 GPa. Straining by the HPS processing was effective to promote the transformation to the ω phase and to maintain the ω phase even at ambient pressure. The reverse transformation from ω phase to α phase occurred at a temperature of ∼110℃ under ambient pressure, while under higher pressure as ∼4 GPa, the ω phase remained stable even at ∼170℃ covered in this study. It was suggested that the reverse transformation from the ω phase to the α phase is controlled by thermal energy.

An integrated system for user-friendly X-ray intensity attenuation in a wide energy range

For undulator hard X-ray beamlines of a wide energy range, the beam intensity control is often needed to regulate the photon flux impinging on delicate detectors. Despite the capability of state-of-the-art X-ray pixel detectors being greatly advanced recently, the frontier undulator beamlines in synchrotron facilities often carry outstanding photon fluxes that are sometimes too high for certain measurements. Here, we report a developed protocol that allows intensity attenuation of an X-ray beam in the 4-23 keV energy range with flexible attenuation factors; a prototype is installed and tested on the 13A biological small-angle X-ray scattering beamline of the 3 GeV Taiwan Photon Source (TPS) of the National Synchrotron Radiation Research Center, Hsinchu, Taiwan. The intensity attenuation system is modified from a commercially available pneumatically actuated, vacuum-type precision X-ray attenuator of ADC ABS-300; the system provides beam attenuation factors covering 8 orders of intensity attenuation for an X-ray beam in 4-23 keV. This was achieved with selected combinations of 10 sets of metal foils comprising different thicknesses of Al, Ti, Cu, and Ta foils. A user-friendly protocol is established to automatically compare a subscribed attenuation factor with all the possible attenuation factors from the 1024 combinations of the 10 sets of foils in the X-ray energy used, and determine a set of the metal foils having a best-matched attenuation factor. Calculation of beam intensity attenuations with the selected foils is coded with Python and integrated into the Experimental Physics and Industrial Control System (EPICS). The input of an attenuation factor is done through a graphical display of the attenuator system based on the Control System Studio (CSS). The developed X-ray beam attenuation system provides a convenient and intuitive beam intensity control and has the potential to be adopted in future beamlines.

Integrate a high precision scan magnet power supply in NSRRC

This work describes the integration of a high precision power supply in a scan magnet in National Synchrotron Radiation Research Center (NSRRC). Horizontal and vertical energy transmission to the scan magnet are independent. The high precision and sinewave are utilised to produce a smooth circle field. This power supply has an air cooling system and a more protective function to keep the machine and magnet from being damaged. During the scan magnet application, the maximum current is 12.5 A, and the inductor is 30 mH at 20 Hz sine wave. Accordingly, Kecpo BOP 72-14 model with a maximum current of 14 A and maximum output voltage of 72 V is chosen. Finally, an integrated high-precision scan magnet power supply is created in the laboratory. Experimental result shows the output current ripple and bandwidth, with the output current being 14 A and the maximum ripple being 0.45 A. This combination is simple because no resistor is in parallel with the magnet coils. Lastly, this work demonstrates the magnetic field, output current ripple, and frequency variation with output current to prove that this power supply meets the requirements.

Damage-Free Femtosecond X-Ray Laser Snapshot Imaging of Catalyst Layer Nano-Structures of Polymer Electrolyte Fuel Cells

The realization of the hydrogen society, where hydrogen is used as clean and renewable energy, is desired to reduce carbon dioxide emissions and achieve sustainable development. The polymer electrolyte fuel cell (PEFC) is a key technology for automobiles in the hydrogen society as an alternative to conventional internal combustion engines. However, further improvements in PEFC performances are required for the full-scale spread of fuel cell vehicles. This study aims to image the nanostructures of the catalyst layer, which is particularly important in determining the performance of PEFCs, and correlate the observed structures with mass transfer in the catalyst layer. The catalyst layer contains catalyst-loaded carbon supports thinly covered with an ionomer responsible for proton conduction. We are especially interested in observing the support structure and ionomer coverage.We performed coherent X-ray imaging studies on the catalyst particles of PEFCs using an X-ray free-electron laser (XFEL) facility: SACLA (SPring-8 Angstrom Compact free electron LAser). Femtosecond XFEL allows us to capture radiation-damage-free snapshot images by outrunning major radiation damage processes. Damage-free imaging is of great value because radiation damage often causes a problem in high-resolution electron microscopy observation of ionomers. We used the coherent diffractive imaging (CDI) technique to observe catalyst particles of PEFCs. In CDI, sample images are reconstructed from measured coherent diffraction patterns using phase-retrieval calculation instead of objective lenses. CDI enables quantitative phase imaging and allows high-contrast imaging of the catalyst particles, which are almost transparent to X-rays.The measurement was carried out for catalyst particles in the dried condition and in solution. Our study showed that the image contrast can be adjusted by changing the electron density of the volume surrounding the sample1). The dried sample was prepared by dropping catalyst ink onto a silicon nitride membrane and air-dried. The solution sample was enclosed in micro-liquid enclosure arrays2,3) developed at Hokkaido University. The coherent diffraction patterns were measured by irradiating the sample catalyst particles with the 100-nm-focused XFEL beam with a photon energy of 4 keV using MAXIC-S (Multiple Application X-ray Imaging Chamber-S)4). The phase-retrieval calculation reconstructed the sample images. Fig. 1 shows a reconstructed image of a catalyst particle in water. The reconstructed image shows many white spots, which can be interpreted as platinum-cobalt catalysts. The pixel size of the reconstructed image is 1.3 nm, demonstrating among the highest spatial resolution in X-ray imaging. We will continue our study to observe the support structures and their ionomer coverage to understand the mass transfer in the catalyst layer.This work was supported by the FC-Platform of NEDO (New Energy and Industrial Technology Development Organization). The XFEL experiments were performed at SACLA with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal Nos. 2020A8106, 2021A8010, and 2021B8019).

Β-Feooh Nanorods As a Highly Active Self-Repairing Anode Catalyst for Alkaline Water Electrolysis Powered By Renewable Energy

The use of renewable energy as a primary energy source is urged because of the rapid progress of global warming. Because the renewable energy is unevenly distributed in terms of place and time, the production of hydrogen from renewable energy is crucial. Alkaline water electrolysis is a cost-effective technology for this purpose, though the degradation of electrodes under fluctuating power of renewable energy is recently regarded as a crucial problem. We have recently reported that a in-situ repair of anode catalyst (self-repairing catalyst), supplying fresh catalyst from electrolyte is quite useful to improve the lifetime under unsteady operation [1]. A hybrid cobalt hydroxide nanosheet (Co-ns) was used as the self-repairing catalyst, whereas its electrocatalytic activity is moderate. In this study, we demonstrate the use of β-FeOOH nanorods (β-FeOOH-nr) as a highly active and durable self-repairing catalyst. Because β-FeOOH-nr consists of iron as a metallic element, it is promising for its low cost and resource abundance. β-FeOOH-nr was synthesized by the coprecipitation of Fe3+ with tris(hydroxymethyl)aminomethane, followed by heating at 80 °C. The width and length of β-FeOOH-nr were 3–6 nm and 4–200 nm, respectively. The Fe K-edge XANES analysis showed that β-FeOOH-nr consists of Fe3+ species. Electrochemical tests were performed in a three-electrode PFA cell, using a nickel wire, a nickel coil, and a reversible hydrogen electrode, as working, counter, and reference electrodes, respectively. The β-FeOOH-nr was dispersed in 1 M KOH as an electrolyte. β-FeOOH-nr was first deposited on the nickel wire electrode by constant current electrolysis at 1 A·cm–2 for 240 min (30 min × 8 cycles). β-FeOOH-nr formed a thin layer of bundled nanorods and exhibited the oxygen evolution reaction (OER) overpotential of 320 mV at 100 mA cm–2, while previously reported Co-ns exhibited 342 mV. In addition, the activation of β-FeOOH-nr-coated electrode is almost finished at the first 30 min of the electrolysis, whereas Co-ns required 240 min for the activation. Because β-FeOOH-nr-coated electrode exhibited high OER activity with a small amount of β-FeOOH-nr deposited on the electrode, β-FeOOH-nr could activate electrode with shorted electrolysis time. The β-FeOOH-nr-coated electrode indicated the redox peak due to Ni2+/Ni3+ at 1.44 V vs. RHE which is at higher potential than that of a bare nickel electrode, implying that β-FeOOH-nr formed composite with active nickel species, such as Ni(OH)2 as highly active materials. The durability of the catalyst-coated electrode was examined in the presence of β-FeOOH-nr in the electrolyte by the newly reported shutdown-based accelerated durability test (SD-ADT) [2]. SD-ADT consists of multiple cycles of constant current electrolysis at 600 mA·cm–2 for 1 min and potential retainment at low potential of 0.5 V vs. RHE for 1 min. A bare nickel electrode is degraded only within 50 cycles by the SD-ADT (OER overpotential reached 640 mV at the 200th cycle), whereas β-FeOOH-nr-coated nickel electrode retained its low OER overpotential of 285 mV in at least 4000 cycles. Comparing with the SD-ADT in the absence of β-FeOOH-nr in the electrolyte, it was shown that β-FeOOH-nr was deposited during the SD-ADT to repair degraded electrode. In conclusion, β-FeOOH-nr was shown to be a useful anode catalyst for alkaline water electrolysis powered by fluctuating renewable energy. By dispersing β-FeOOH-nr in an electrolyte, the alkaline water electrolyzer can establish self-repairing system with very long lifetime under frequent potential change. The synchrotron radiation experiments were performed at the BL16B2 of SPring-8 with approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2021A5310). This work was supported by the JSPS KAKENHI (grant number 20H02821) from Ministry of Education, Culture, Sports, Science and Technology (MEXT) Japan. Part of this study uses outcomes of the development of fundamental technology for the advancement of water electrolysis hydrogen production in the advancement of hydrogen technologies and utilization projects (grant number JPNP14021) commissioned by the New Energy and Industrial Technology Development Organization (NEDO) in Japan.

High Resolution Observation of Liquid Water in Polymer Electrolyte Fuel Cell Using X-Ray Nano Computed Tomography

Polymer electrolyte fuel cells (PEFCs) are attracting attention as energy device of low environmental impact because of their high generation efficiency and their emitting only water. The gas supplied to the PEFC is humidified, and water is produced at the cathode catalytic layer by the electrochemical reaction between oxygen and protons. The gas diffusion layer (GDL) and micro porous layer (MPL) in PEFC plays an important role in the transport of oxygen and water. When liquid water accumulates in the GDL, the supply of oxygen to the cathode is inhibited, resulting in poor generation performance. In order to maintain the performance of PEFCs, it is important to manage the water in the cell.Attempts have been made to visualize the liquid water in GDLs and MPLs for better GDL and MPL design; X-ray micro computed tomography (micro-CT) is one powerful tool for this. Visualization of liquid water in GDLs and MPLs using micro-CT has so far revealed the behavior of the produced water[1,2]. However, in previous studies, it has been difficult to visualize liquid water in the catalyst layer, which is the reaction field where the water is produced. This is because the spatial resolution of micro-CT is larger than a µm, which is insufficient for analyzing liquid water in the catalytic layer. X-ray CT measurements with a resolution of at least 150 nm are needed to measure the distribution of liquid water in the cross section of the catalyst layer. In this study, a measurement system to reveal the distribution of liquid water in the catalyst layer was developed using a 150 nm-spatial-resolution X-ray CT with a synchrotron radiation x-ray microscope called X-ray nano-CT.A GDL specimen prepared cut to a disk shape with 1 mm diameter. The GDL specimen mounted on a copper stage with high thermal conductivity connected Peltier element module. The micro-CT and nano-CT measurements were carried out in BL20XU beamline at SPring-8, Japan. An X-ray beam energy was 30 keV with a double crystal monochromator. The nano-CT measurements were performed using Zernike phase contrast with voxel size of 38.4 nm. We measured the micro-CT and nano-CT of the dry condition of the GDL specimen. Then, the GDL specimen injected liquid water was scanned. Injection of liquid water into the GDL specimen is not easy because of water-repellent of GDLs. Helium gas saturated water vapor at 40 °C was sprayed to the GDL at 30 ml/min, then the GDL cooled to 10 °C using a Peltier element module and the vapor was condensed inside of the GDL. The measurement setup is shown in Figure 1. This water injection in GDL method was based on the method reported by Kato et al [2].Figure 2 shows the optical system of the nano-CT used in this study. The optical system of this nano-CT provides a condenser zone plate for sample illumination, a Fresnel zone plate for enlarged image, and phase ring for Zernike phase contrast. These optics allow CT with a high spatial resolution of 150 nm to be measured even for materials with low X-ray absorption.A three-dimensional structure of GDL was revealed by CT measurements in each scale order. The distribution of liquid water in GDL were visualized with nanoscale spatial resolution (Figure 3). We have successfully visualized the three-dimension distribution of liquid water in the GDL with nm order scale using nano-CT. The newly established nano-CT with a spatial resolution of 150 nm order is extremely useful for elucidating liquid-water behavior in PEFCs containing catalyst layers, which was not clear before. Acknowledgements This work is based on results obtained from a NEDO FC-Platform project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). This study was partially supported by the Synchrotron radiation experiments performed at BL20XU of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal numbers 2021A2009, 2021B1015).

Using Synchrotron Techniques, Investigation of Electrochemical Interfaces in Ni-Rich NMC and Sulfide Electrolytes in All-Solid-State Lithium Metal Batteries

a Nano-electrochemistry Laboratory, Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan, R.O.C b National Synchrotron Radiation Research Center (NSRRC), Hsinchu, 30076, Taiwan, R.O.CIn all-solid-state lithium metal batteries enable long cyclability of high voltage oxides cathode persistent problem for the large scale application as their underprivileged interfacial steadiness in contrast to sulfide solid-state electrolyte. In this context, the interfaces of the solid electrolyte and Ni-rich NMC811 active material are looked upon as interfacial chemical responses induced by delithiation. In this study, we monitor the impedance progress at the unstable electrode|electrolyte interface due to the electrochemical interfacial response and help us understand the complex nature of reactivity and degradation kinetics with the solid-solid interface redox decomposition, which makes decoupling each effect difficult. we investigated the interfacial phenomenon between LPSC and high voltage cathode NMC811. The effects of spontaneous retort by the side of the interface were separated, and the intrinsic electrochemical decomposition of LPSC was quantified. Moreover, we show that the notch of interfacial degradation surges and the presence of oxidation mechanisms. At the higher delithiation stage, the cathode might twitch structural defenselessness and oxygen utter and resulting in further stark degradation. This complex kinetic degradation behavior was investigated at the solid-solid interface in a delithiation NMC811 and SSE based on the local oxidation state of NMC811, and LPSC SE interfacial chemical response. In this work, we used various characterization techniques to investigate the interfacial phenomenon between LPSC|NMC811 combining EIS and advanced synchrotron techniques such as sXAS, XPS, XRF-XANES mapping, and In-situ Raman spectroscopy. Keywords: delithiation, Ni-rich cathode, Sulfide-solid-state electrolyte, interfacial reaction, Synchrotron XPS, XRF.

Microscopic Views of Ge Segregation and Scavenging Ge on Thin Si on Epi-Ge(001)

Si capping layer is the most notable approach used in Ge metal-oxide-semiconductor (MOS);1-2 however, the Ge segregation and diffusion occurred during the growth of Si.3-4 The formation of undesirable GeOx is detrimental to the Ge nMOS reliability.5 This work focuses on using the scavenging process to reduce the segregated Ge atoms and to completely remove GeOx in the high-k/epi-Si/epi-Ge(001). We used high-resolution synchrotron radiation photoelectron spectroscopy (SRPES) to show the detailed development of Ge segregation and scavenging Ge using in-situ film growth, oxidation, and annealing. The Si films in 8Å thickness were grown on the epi-Ge(001) in a semiconductor molecular beam epitaxy (MBE) chamber.2 These samples were in-situ transferred to National Synchrotron Radiation Research Center in Taiwan for electronic structure studies using photoemission. Molecular oxygen was exposed to the epi-Si/epi-Ge(001) surfaces at 300°C in the photoemission chamber. The samples were then in-situ annealed at 500°C for 5 min under an ultra-high vacuum (UHV).The topmost surface of epi-Ge(001) is terminated with Ge-Ge buckled dimers.6 In the case of room-temperature grown amorphous Si (a-Si) film, the intensity of the Ge down-dimer component from the underlying epi-Ge remains as it is. The Ge up-dimer atoms were partly diffused into the a-Si film, and some of them were segregated to the top of the a-Si surface. The epi-Si grown at 260 - 280°C causes the rest of the Ge down-dimer atoms to move to the epi-Si surface to become both segregated Ge (segGe) and diffused Ge (diff-Ge). The growth of Si merely affects the topmost surface, and the Ge atoms in the second layer of the epi-Ge remain intact. A comparison of the amount of GeOx for HfO2/epi-Si/epi-Ge(001) and HfO2/epi-Ge(001) shows that the epi-Si has greatly reduced the amount of GeOx. However, the GeOx, segGe and diff-Ge components are still observed in the HfO2/epi-Si/Ge(001) samples.We have previously reported that three-time scavenging cycles have greatly reduced the amount of segGe and diff-Ge atoms in high-κ/epi-Si/n-Ge(001), thus decreasing electron traps.7 Each scavenging cycle includes room-temperature oxidation followed by thermal annealing. In this study, the oxidation of the as-grown epi-Si/epi-Ge(001) samples was performed at 300°C. It is worth noting that there is no GeOx formation on the surface after the thermal oxidation, which is different from the room-temperature oxidation of the epi-Si/epi-Ge(001) surfaces. In addition, the oxidation at 300°C affects part of the diff-Ge atoms to evaporate from the surface, which is also different from our previous work, where the diff-Ge component shows no change in intensity since the oxidation occurred at room temperature. The subsequent in-situ annealing at 500°C moved the residual Ge-boned Si (diff-Ge) inside the epi-Si to the surface to become part of the segGe atoms. In conclusion, we have used the aforementioned process to further reduce the segregated Ge, and thus the GeOx, on top of the epi-Si/epi-Ge(001).To whom the correspondence is addressed: mhong@phys.ntu.edu.tw (M. Hong), raynien@phys.nthu.edu.tw (J. Kwo), and pi@nsrrc.org.tw (T. W. Pi)AcknowledgmentsThis work is supported by MOST 110-2112-M-002-036-, 110-2622-8-002-014-, 110-2923-M-002-001-, and 110-2112-M-213-012- of the Ministry of Science and Technology in Taiwan.Reference 1 H. Arimura, E. Capogreco, A. Vohra, C. Porret, R. Loo, E. Rosseel, A. Hikavyy, D. Cott, G. Boccardi, L. Witters, G. Eneman, J. Mitard, N. Collaert, and N. Horiguchi, IEEE Int. Electron Devices Meet., 2.1.1−2.1.4 (2020). 2 H. W. Wan, Y. J. Hong, Y. T. Cheng, C. K. Cheng, C. H. Hsu, C. T. Wu, T. W. Pi, J. Kwo, and M. Hong, M., ACS Appl. Electron. Mater. 3, 2164−2169 (2021). 3 R. Loo, H. Arimura, D. Cott, L. Witters, G. Pourtois, A. Schulze, B. Douhard, W. Vanherle, G. Eneman, O. Richard, P. Favia, J. Mitard, D. Mocuta, R. Langer, N. Collaert, ECS J. Solid State Sci. Technol. 7, 66−72 (2018). 4 Y. T. Cheng, H. W. Wan, C. K. Cheng, C. P. Cheng, J. Kwo, M. Hong, T. W. Pi, Appl. Phys. Express 13, 085504 (2020). 5 J. Franco, B. Kaczer, P. J. Roussel, J. Mitard, S. Sioncke, L. Witters, H. Mertens, T. Grasser, G. Groeseneken, IEEE Int. Electron Devices Meet., 15.2.1−15.2.4 (2013). 6 Y. T. Cheng, Y. H. Lin, W. S. Chen, K. Y. Lin, H. W. Wan, C. P. Cheng, H. H. Cheng, J. Kwo, M. Hong, T. W. Pi, Appl. Phys. Express 10, 075701 (2017). 7 Y. T. Cheng, H. W. Wan, T. Y. Chu, T. W. Pi, J. Kwo, M. Hong, ACS Appl. Electron. Mater. 3, 4484-4489 (2021).

Identifying Key Descriptors for the Single-Atom Catalyzed CO Oxidation

Identifying Key Descriptors for the Single-Atom Catalyzed CO Oxidation

Vacuum and Surface Science by Synchrotron Radiation Research

Vacuum and Surface Science by Synchrotron Radiation Research

Crystal orientation and residual stress in TiN film by synchrotron radiation

Abstract The residual stress in a TiN film, the thickness of which is less than 1 µm, deposited by arc ion plating was measured using the SPring-8 synchrotron radiation facility installed at Japan Synchrotron Radiation Research Institute (JASRI). Films thicker than 300 nm have a {111} texture, whereas those with a thickness of 100 nm have a relatively random orientation. Instead of the conventional laboratory X-ray equipment, ultrabright synchrotron radiation can be used to precisely measure the residual stress in thin films with a thickness of 100 to 800 nm. The residual stress in thicker TiN films is about 7 GPa in compression and it is not affected by the film thickness. The slightly small compressive stress in a film of 100 nm in thickness may be due to the different crystal orientations in the film.