bluuebunny/crossref_metadata_2025 huggingface dataset:
Saline Water Electrolysis Membranes Prepared via the Simultaneous Irradiation of Electron-Beam
Authors: Park In Kee , Cha Woo Ju , Lee Chang Hyun
Published: December 2020

Polymer electrolyte membrane water electrolysis is a representative electrochemical process to produce both hydrogen and oxygen gases by applying electricity. Perfluorinated sulfonic acid (PFSA) ionomers have been widely used as electrode binder materials owing to their high proton conductivity and excellent compatibility with membrane materials with identical or similar chemical architectures. Different in the membrane materials, PFSA binder materials should have fast gas permeation behavior to minimize mass flux resistance. It makes it difficult to use the same ionomer dispersion for both applications. In this study, the average size of dispersed PFSA ionomer particle was controlled via a supercritical technique. The relationship between ionomer dispersion characteristics and electrochemical performances was systematically investigated.
High Pressure Water Electrolysis Using a Hydrophobic Gas Diffusion Layer with a New Cell Structure of Water Absorbing Electrolyte Cell
Authors: Vediyappan Veeramani , Lai Qiwen , Sone Yoshitsugu , Furukawa Shoichi , Matsumoto Hiroshige
Published: December 2020

Nowadays, the usage of fossil fuel has been raised as a non-sustainable resource, account for the main contributor to global warming (CO2 emission) and environmental pollutions. In this regard, the hydrogen production through polymer electrolyte membrane (PEM) water electrolysis is an industrially important approach to resolving the above energy issues. Precious metals are the top metal-catalysts that can offer to generate hydrogen efficiently and earth-abundant nonprecious metal catalyst has large overpotential issues because of a low electro-activity. Therefore, the production of pressurized hydrogen through polymer exchange membrane (PEM) water electrolysis without the usage of the external compressor is an industrially important approach to maximize energy efficiency. Because hydrogen is believed to be a clean energy carrier to store the excess renewable energy to resolve its intermittent issues. Although over 96% of the current hydrogen produced is via the reformation of natural gas and the remaining 4% produced from water electrolysis and it is the “green” approach to produce hydrogen without CO2 emission. In this report, we demonstrated the operation of a new water electrolysis cell at high water support pressure with the assistance of a hydrophobic gas diffusion layer (H-GDL) and demonstrated a high-pressure PEM water electrolysis experiment with the assistance of a newly structured water electrolysis cell (Fig.1a). The membrane electrode assemblies (MEAs) was prepared using H-GDL, membrane, Pt-C//IrO2 and the electrolysis experiment was performed at different temperature and water support pressure (ΔP = 0.05-0.4 MPa). The current density obtained at 1.6 V were 117, 188, 262 mA cm-2 at 25, 60, and 80oC (Fig.1b), respectively, and the generated gas evolution rates (hydrogen and oxygen) were consistent with theoretical value with efficiencies up to 87%. It was found that increasing water pressure is beneficial to the electrode kinetics and mass-transportation due to an increase in water transport to the electrode surface and efficient gas separation. The benefits of using GDL is, therefore, lying on two points. Firstly, high pressure can be applied to the water, which allows the operation of the cell at a temperature higher than 100℃, while maintaining the water in the liquid phase and secondly the high-pressure operation using H-GDL is the production of pressurized hydrogen gas without the use of an external compressor. As advantages, in the future, it can be directly used to fuel cell and that can be stored in a hydrogen tank without further purification process.

Figure 1
Fused Hybrid Linkers for Metal–Organic Frameworks-Derived Bifunctional Oxygen Electrocatalysts
Authors: Alam Mahboob , Ping Kefeng , Bhadoria Rohit , Tammeveski Kaido , Kongi Nadezda , Starkov Pavel
Published: December 2020

Noble metal free M-N-C oxygen electrocatalysts are generaly synthesized using inorganic salts, organometallic precursors, nanostructured carbon nanotubes, several dopants and carbonization under modifying environments such as NH3 or H2. Reducing synthesis steps or bringing versatility in post product is quite rare. We have introduced a series of metal-organic frameworks using iron/benzimidazole as the only primary precursor to obtain a uniform material. By merging catechol and imidazole units together, we prepared efficient bifunctional oxygen electrocatalyst. The proposed material outperforms the Pt-based materials with respect to electrocatalytic properties in alkaline media (ORR: Eon = 1.01 V, E1/2 = 0.87 V vs. RHE in 0.1 M KOH; OER: 1.60 V @10 mA cm–2 in 0.1 M KOH; ΔE = 0.73 V). It was also established that fine-tuning of organic linker can help to modulate the electrochemical properties of the single precursor based electro-catalyst material.
Gas Phase Electrolysis of Anhydrous HCl for Dry H2 Production
Authors: Likit-anurak Kris , Brizes Michael , Shimpalee Sirivatch , Lopata Joseph Steven , Weidner John W. , Murdock Laura , Benicewicz Brian C , Meekins Benjamin
Published: December 2020

Chlorine (Cl2) is an important feedstock used in a variety of industry processes [1]. Hydrogen (H2) and chlorine gas (Cl2) can be produced by the electrochemical oxidation of hydrogen chloride (HCl) anhydrous gas. Previously, a gas phase hydrogen bromine (HBr) electrolyzer showed better performance than aqueous phase due to a significant increase in reactant diffusion rate [2-5]. Furthermore, sulfonated polybenzimidazole (s-PBI) membranes have shown promising performance in this application because they can be operated in strong acid environments and at high temperature [6].

The propose of this work was to elucidate the role of the polymer membrane, the efficiency and durability of cathode catalyst (Pt vs IrRuOx), and the optimal operating parameters (temperature, flow rate, and cell potential). We found that the s-PBI gel membrane doped in 50 wt% H2SO4 showed significantly better performance than NafionTM membranes, regardless of their thickness, due to a reduction in membrane resistance and a decrease in chloride ion crossover. We considered as well how crossover of Cl- from anode to cathode can poison the cathode catalyst, affecting the durability of the electrolyzer. We also discuss how the cell temperature and HCl flow rate affect the performance of the electrolyzer, with a focus on reducing the cell potential required to electrolyze HCl by increasing the reaction temperature.

References:

[1] The American Chemistry Council (ACC). “2017 Elements of the Business of Chemistry” NE Washington, DC: [Online] Available: https://www.americanchemistry.com/2017-Elements-of-the-Business-of-Chemistry.pdf

[2] B. Huskinson, J. Rugolo, S.K. Mondal, M.J. Aziz, Energy & Environmental Science. 5 (2012) 8690.

[3] F. Mohammadi , S.N. Ashrafizadehb, A. Sattari, Chemical Engineering Journal 155 (2009) 757–762.

[4] V. Barmashenko and J. Jo"Rissen, Journal of Applied Electrochemistry 35 (2005) 1311–1319

[5] P. Sivasubramanian, R.P. Ramasamya, F.J. Freireb, C.E. Hollanda, J.W. Weidner, International Journal of Hydrogen Energy 32(4) (2007) 463-468.

[6] T. R. Garrick, C. H. Wilkins, A. T. Pingitore, J. Mehlhoff, A. Gulledge, B. C. Benicewicz, J. W. Weidner, J. Electrochem. Soc. 2017, 164(14), F1591-F1595
Three-Dimensional, Two-Phase Computational Fluid Dynamics Simulations of Alkaline Diaphragm Water Electrolysis Devices
Authors: Lopata Joseph Steven , Kang Sanggyu , Cho Hyun-Seok , Kim Chang Hee , Shimpalee Sirivatch
Published: December 2020

Alkaline diaphragm water electrolysis (ADWE) devices are the most widely commercialized water splitting cells for large-scale applications. They are inexpensive and durable, but they undergo numerous voltage loss mechanisms that are absent in ion-exchange cells.1 Computational studies enable us to understand these losses and to engineer components that diminish them. Hammoudi et al.2 developed a validated one-dimensional multi-physics model incorporating bubble effects and compared relative overpotentials at different temperatures. Abdin et al.3 used a multi-physics approach that included electrode and separator properties to show effects of design parameters on performance.

Our aim is to utilize computational fluid dynamics techniques to build an ADWE model that enables us to effectively engineer the flow field and porous transport layer (PTL). This two-phase model considers losses due to the presence of bubbles in the electrolyte, bubbles on the electrode surface, and shunt current through the diaphragm. We include a discussion of the current distribution in a straight channel ADWE device and what factors are important to consider for optimizing productivity and efficiency.

References:

M. Schalenbach et al., Journal of The Electrochemical Society, 163, F3197–F3208 (2016).

M. Hammoudi, C. Henao, K. Agbossou, Y. Dubé, and M. L. Doumbia, International Journal of Hydrogen Energy, 37, 13895–13913 (2012).

Z. Abdin, C. J. Webb, and E. M. A. Gray, Energy, 138, 316–331 (2017).
Effects of Inadequate Current Collection on Impedance of Solid State Electrodes
Authors: Witt Jonathan Michael , Collins Ryan , Adler Stuart B.
Published: December 2020

Impedance measurements of SOEC, SOFC, and other high temperature solid state electrodes often employ a current collector to insure a laterally homogeneous current density. During recent measurements of H2O and CO2 reduction on rare-earth doped ceria electrodes, we found that inadequate current collection leads to distortion of the impedance response. This distortion not only involves quantitative inaccuracies due to reduced active area, but also changes in the shape and frequency response of the electrodes. In order to better understand these results, we have developed a general model, based on frequency-resolved finite element analysis, for the impacts of finite current collection on impedance. This model predicts a number of surprising results, including severe distortions particularly in the high frequency portion of the spectrum, appearance of apparent Warburg features when none is present in the actual electrode response, shifts in characteristic resistance and frequency of the electrodes, and misattribution of electrolyte resistance to electrode response. This model may help explain a number of seemingly anomalous impedance features often reported by authors.
(Invited) Mixed Protonic-Electronic Membrane Reactors; Converting Hydrocarbon Resources and CO2 to Fuels
Authors: Wachsman Eric
Published: December 2020

Membrane reactor technology holds the promise to circumvent thermodynamic equilibrium limitations by in-situremoval of product species, resulting in improved chemical yields. Recent advances in mixed-conducting oxide-membrane technology present the possibility for a dramatic reduction in the cost of converting petroleum, coal and biomass derived feed stocks to hydrogen and other “value added” hydrocarbons. We have developed novel membrane reactor technology, based on high temperature proton conductors, that can convert a wide range of hydrocarbons to pure H2, and syngas for synthesis of liquid fuels and chemical feed stocks. By simultaneous H2 permeation and catalysis, we have demonstrated the ability to increase water gas shift yields >70% over thermodynamic limitations. Similarly, we have demonstrated increases in steam reforming yields, and the ability to reform CH4 with CO2.

More recently we have developed single-step gas to liquid reactors that convert natural gas to C2+ products with high yields and no unwanted oxidation byproducts. The direct utilization of CH4 and CO2 to simultaneously produce C2+hydrocarbons (C2 and aromatics) and syngas (CO and H2) on opposite sides of a mixed protonic-electronic conducting SrCe0.7Zr0.2Eu0.1O3-δ membrane reactor is demonstrated. On one side (interior) of the membrane reactor, direct non-oxidative methane conversion (DNMC) over an iron/silica catalyst produces C2+ hydrocarbons and H2. On the other side (outer surface) of the membrane, permeated H2 (driving the DNMC reaction) reacts with a CO2 sweep gas to form CO and water via the reverse water gas shift (RWGS) reaction. This novel single H2-permeable membrane reactor simultaneously addresses both reduction of greenhouse gas (CO2 and CH4) emissions as well as production of value-added hydrocarbon products (C2+, CO, and H2) with in situ gas separation.
Operando Optical Studies of Sulfur Contamination in Syngas Operation of Solid Oxide Fuel Cells
Authors: Maza William A , Pomeroy Elias D , Steinhurst Daniel A , Tsoi Stanislav , Walker Robert A. , Owrutsky Jeffrey C.
Published: December 2020

Solid oxide fuel cells (SOFCs) are attractive devices for power generation because they can operate under a variety of fuels, including H2, hydrocarbon fuels, biogas, and syngas (CO + H2). Syngas is an important fuel since it is a major product of reforming hydrocarbon logistics fuels (i.e. JP-8, JP10, S8, etc.). However, the mechanism of electrochemical oxidation of CO in SOFCs is still not well understood. This is due, in part, to the difficulty in probing CO consumption and product formation under operating conditions in real time. Herein, the operando methods Fourier transform infrared emission spectra (FTIRES) of the SOFC headspace together with thermal imaging data of the Ni-YSZ anode surface to provide data relevant to understanding these reaction mechanisms. The studies are carried out on anode-supported SOFCs (Ni-YSZ/GDC-LSC button cells) operating on simulated syngas mixtures. The contamination and subsequent degradation of SOFC operation at operational temperatures of 600° C to 800° C, in the presence of sulfur concentrations below 30 ppm, is followed using potentiostatic spectroelectrochemistry, chronocoulometry, electrochemical impedance spectroscopy, and operando optical methodologies to provide a comprehensive picture of the processes occurring in the fuel oxidation. Together, the data obtained indicate that sulfur contaminants 1) competitively inhibit formation of carbon over CO catalytic and electrocatalytic sites, and 2) induce changes of the Ni-YSZ anode permanently perturbing their catalytic and electrocatalytic function.
Assessing Sulfur-Induced Degradation Mechanisms in SOFCs with Operando Thermal Imaging and Chronocoulometry
Authors: Pomeroy Elias D , Maza William A , Steinhurst Daniel A , Owrutsky Jeffrey C , Walker Robert A.
Published: December 2020

Solid Oxide Fuel Cells (SOFCs) show significant promise for future power generation due to their high efficiencies and fuel flexibilities. Their susceptibility to a number of degradation pathways while operating on carbon containing fuels remains a significant impediment to wider adoption of this technology. Sulfur susceptibility, especially given sulfur’s ubiquitous presence in carbon fuel feedstocks, has been widely studied, yet the mechanism for sulfur poisoning has yet to be established due to the difficulty of studying SOFCs in operando. Additional insight into sulfur induced degradation of SOFCs anodes was developed by using Near-IR Thermal Imaging and Raman Spectroscopy, both of which are effective tools for studying SOFCs, as well as adapting a classic quantitative electrochemical technique, chronocoulometry, to SOFCs. The studies were carried out on commercial electrolyte button cells operated between 600-800 °C, in sulfur environments of 0-50 ppm H2S with H2 as the primary fuel. The data shows that more sulfur is adsorbed to the anode catalytic sites at lower temperatures. Additionally, the data indicates that sulfur not only blocks active sites, but also participates in electrochemical processes at the anode.
Highly Efficient and Durable Materials for Protonic Ceramic Electrochemical Cells Operated at 400~600 ○c
Authors: Ding Hanping , Ding Dong
Published: December 2020

Protonic ceramic electrochemical cells (PCECs) is an emerging and attractive approach to store intermittent renewable energies which can be converted back to electricity in reversible operation, aiming to achieve the energy conversion and storage in an electrochemical manner. Economically competitive PCEC systems have distinct advantages over conventional oxygen-ion conducting counterpart (O-SOC), but further materials innovation is still needed to improve unit-cell performance and durability at reduced operating temperature (400~600○C), enhance system lifetime and reduce cost. To achieve efficient electrochemical hydrogen and power production with stable operation, highly robust and durable oxygen electrode is urgently desired to facilitate water oxidation and oxygen reduction reactions simultaneously, which are the critical technical barriers for both electrolysis and fuel cell operation at reduced temperatures. The recent efforts have been focused on developing new triple conducting electrode with perovskite perovskite structure for high-performance and stable PCECs. The systematic material characterizations are carried out to evaluate the feasibility of activity, stability and interface compatibility, such as Fourier-transform infrared spectroscopy, high-temperature X-ray diffraction, hydrogen permeation and first-principal computation. The catalytic activity towards electrochemical reactions is demonstrated in various electrochemical performance evaluations at 400~600○C. The long-term durability of the PCEC is examined to show the high resistance against transient current density change in reversible operation and high steam concentration.
Resolving Heterogeneity in Battery Interphases By Cryogenic Electron Microscopy
Authors: Huang William , Wang Hansen , Boyle David , Li Yuzhang , Cui Yi
Published: December 2020

The stability of lithium batteries is tied to the physicochemical properties of the solid-electrolyte interphase (SEI), a surface passivation layer on the battery anode. However, owing to the difficulty in characterizing this sensitive interphase with nanoscale resolution, the distribution of SEI components at the nanoscale is poorly understood. Here, we use cryogenic scanning transmission electron microscopy (cryo-STEM) and electron energy loss spectroscopy (EELS) to map the spatial distribution of sensitive SEI components across the metallic Li anode. We reveal that LiF, an inorganic SEI component widely believed to play an important role in battery passivation, is absent within the compact SEI film (~15 nm) in direct contact with the active material. Instead, LiF particles (100-400 nm) are found to precipitate across the electrode surface independently from compact SEI formation. Based on these observations, we conclude that LiF cannot be a dominant contribution to anode passivation nor does it influence Li+ transport across the compact SEI film. Using cryo-STEM and EELS, we refine the traditional view of the SEI structure derived from ensemble-averaged characterizations and nuance the role of SEI components on battery performance.
Performance and Stability Enhancement of Ni-Based Cermet Anode Using Atomic Layer Deposited Ruthenium for Direct Methane-Fueled Low-Temperature Solid Oxide Fuel Cell
Authors: GO Dohyun , Kye Seunghyeon , Yang Byung Chan , Kim Hyong June , Shin Jeong Woo , Lee Sungje , An Jihwan
Published: December 2020

Nickel (Ni) based cermet, e.g., Ni-doped zirconia(e.g., YSZ) and Ni-doped ceria(e.g., GDC), is the most widely used anode material for solid oxide fuel cell (SOFC). SOFC has been considered as a promising energy converter because of its high efficiency, eco-friendliness, and fuel flexibility. However, recently, SOFC operating below 500°C with more conventional fuels such as hydrocarbon or alcohol are actively studied for overcoming the limitations of high temperature SOFC, e.g., durability, cost, and limited application. Therefore, the necessity of improving the performance and stability of Ni-based anode is aroused because it shows relatively slow hydrocarbon and alcohol oxidation kinetics in the low-temperature regime and vulnerable to carbon deposition. To improve kinetics and stability of Ni-based anode upon hydrocarbon fuel-based operation, various kinds of metal catalysts, e.g., copper, palladium, iron, etc., have been applied using fabrication techniques such as wet synthesis, infiltration, vapor deposition, etc.

In this study, ruthenium (Ru) having high catalytic activity and carbon coking toleration is applied to Ni-based cermet anode used in methane-fueled low-temperature SOFC. In particular, atomic layer deposition (ALD), which can deposit nanoparticles conformally on porous structures, is used for depositing Ru nanoparticles on nano-structured Ni-based cermet anode. ALD Ru nanoparticles fabricated in such a way are well-dispersed on the surface of Ni-based cermet anode and effectively improve the performance and stability of the anode when it is operated with methane-fuel. Especially, Ni-based anode with optimal ALD Ru thickness, i.e., 10nm in thickness, shows 40% higher maximum power density than those without ALD Ru overcoating when operated with methane fuel.
Development of Various Solid Oxide Cell Technology and Stack Platforms at Nexceris, LCC
Authors: Dogdibegovic Emir , Lockhart Cody , Kopechek David , Sellers Chad , Arkenberg Gene , Swartz Scott , Kidner Neil J.
Published: December 2020

With over 25 years of experience in solid oxide fuel cell (SOFC) materials, components and stack development, Nexceris has been rapidly expanding the technology portfolio. Development in Fuel Cell Materials, FlexCell and ChromLok technology are only a few examples. Stack testing capability up to 5 kW has been developed. Modular high-performance stack platforms that accommodate cells from 40 cm2 to 250 cm2 are being utilized, depending on customer requirements and system needs.

Recently, Nexceris expanded its R&D efforts into solid oxide electrolysis cell (SOEC) technology. Initial performance of -1.5 A/cm2 and 500-hour durability tests at 1.3-1.4 V and 800 °C in short stacks show promising platform for further SOEC performance and durability improvements. Besides anode- and electrolyte- supported cell development, metal-supported cells (MSCs) have also been successfully developed at Nexceris and scaled to 250 cm2. The structure, performance and durability of MSCs are being continuously improved. Short 5-cell stacks are currently being demonstrated and the results will guide further stack development. A wide range of cell and stack technology developed at Nexceris provides capability to tailor cells and stacks based on user applications, whether those include continuous non-interrupted stationary operation or dynamic operation such as rapid thermal and redox cycling in mobile applications.
Redox Re-Activation of Steel-Supported Solid Oxide Cells
Authors: Skafte Theis Løye , Tucker Mike C , Graves Christopher
Published: December 2020

Wide-spread commercial application of the solid oxide cell (SOC) technology is hindered by limited lifetime and high fabrication cost. Development has largely been focused on material choice and manufacturing techniques to improve performance and mitigate degradation mechanisms.

Here we instead present an innovative approach to prolonging device lifetime, namely by re-activating the electrodes periodically during operation. This can counteract steady degradation, and thereby avoid expensive replacement of the damaged stack. With the right procedure and materials, this can be accomplished by simple redox cycling.

First, a comprehensive overview of several known re-activation methods for different electrodes is given, including the current mechanistic understanding of each one. Second, we demonstrate the process on model electrodes for proof-of-concept. Third, we optimize the procedure for next-generation metal-supported SOCs, which have the potential to substantially lower manufacturing costs. For these specific cells it is investigated what the optimal procedure is, whether both electrodes can be re-activated, whether the effect is long-lasting, and how the effectiveness compares to all-ceramic electrodes. Lastly, we examine the underlying mechanism.

Figure 1. Electrochemical impedance spectra of a steel-supported SOC being re-activated with a redox cycle after 500 h of aging at open-circuit voltage, 650 °C and H2:H2O 0.8:0.2.

Figure 1
Next Generation Electrically Conductive and Protective Coating for Planar SOFC Stacks
Authors: Choi Jung Pyung , Hardy John S
Published: December 2020

Ferritic stainless steels are preferred to interconnect materials for intermediate temperature SOFCs because of their resistance to oxidation, high formability, and low cost. However, their protective oxide layer produces Cr-containing volatile species at SOFC operating temperatures and conditions, which can cause cathode poisoning. Electrically conducting spinel coatings have been developed to prevent cathode poisoning and to maintain an electrically conductive pathway through SOFC stacks. PNNL demonstrated the Mn-Co-O type of spinel coating on the interconnect part and delivered a great result. However, the industrial partners need the cost down of these coating materials. Hence, PNNL starts investigating next-generation coating materials. This paper will focus on the electrically conductive coating process.
Mechanism Underlying Electron-Transfer Reactions Involving TEMPO and 4-Hydroxy-TEMPO in Deep Eutectic Solvents
Authors: Ijjada Mahesh , Shaheen Nora A. , Vukmirovic Miomir B , Akolkar Rohan
Published: December 2020

Deep eutectic solvents (DES) such as ethaline are considered low-cost, environmentally-benign and non-toxic electrolytes which possess wide electrochemical stability windows. Therefore, these non-aqueous DES electrolytes are attractive for electrochemical applications such as redox flow batteries. However, key drawbacks in applying DES electrolytes include their high viscosities (manifesting in sluggish transport) and sluggish electron-transfer reaction rates [1]. Additionally, mechanistic insights into electron-transfer reactions involving redox-active organic species added to a DES medium are presently unavailable. In this presentation, we report experimental and modeling investigations into the electrochemical oxidation of TEMPO [(2,2,6,6-Tetramethylpiperidin-1-yl)oxyl] and 4-Hydroxy-TEMPO in ethaline DES. Specifically, we present evidence that electrochemical oxidation of TEMPO or 4-Hydroxy-TEMPO involves a two-stage process in which electron transfer is followed by adsorption of the oxidized molecules which either block the electrode surface or gradually desorb and diffuse away into the electrolyte. Mathematical modeling of this two-stage process allows quantitative analysis of experimental polarization curves and cyclic voltammograms. Furthermore, electron-transfer associated with aforementioned organics in DES is compared to and contrasted with analogous processes in aqueous electrolytes to gain additional insights into the proposed ‘adsorption-reaction-desorption’ mechanism.

Reference:

[1]. Shen. D., Vukmirovic. M. B. and Akolkar. R. 2019 J. Electrochem. Soc.
166 E526.
Design and Discovery of Nitride Phosphors with Unique Properties
Authors: Xie Rong-Jun , Li Shuxing
Published: December 2020

Inorganic luminescent materials, acting as color converters, play key roles in solid state lighting. Among a large quantity of phosphors, nitride phosphors have attracted great attentions as they show promising photoluminescence properties (i.e., high conversion efficiency of blue light, thermally robust, and abundant emission color). With advances in solid state lighting techologies, phosphors with desired properties are reuiqred, which is thus necessary to search for appriporate phosphors. In this presentation, we will introduce two nitride phosphors, Sr2AlSi2O6N:Eu2+ and La2.9Si6-x
Al
x
N11-x/3:Ce3+. Sr2AlSi2O6N:Eu2+ was predicted by using high-throughput calculations, and synthesized in a gas-pressure sintering furnace at 1400oC. The crystal structure of Sr2AlSi2O6N (space group: P4̅21m) was derived from Ba2ZnGe2S6O (ICSD no. 14174) via a multispecies substitution of Ba2+ with Sr2+, Zn2+ with Al3+, Ge4+ with Si4+,S2− with O2−, and O2− with N3−. This phosphor showed a super-broad emissin band spaning from 400 to 850 nm and a full-width at half maximum (fwhm) of 230 nm, under 330 nm excitation. The super-broad emission was ascribed to the structural disorder of Si/Al and O/N. Combined with a UV LED, Sr2AlSi2O6N:Eu2+ enabled to produce a white LED with superior color quality (Ra = 97, R9 = 91). La2.9Si6-x
Al
x
N11-x/3:Ce3+ (LSN:Ce,Al) was designed by applying the interstitial site engineering strategy, i.e., partially substituting Si by Al. The introduction of Al in the lattice created a new site for Ce3+, leading to an additional red emission (λ
em = 600-665 nm). The origin of this red emission was assigned from the first-principles calculation to the Ce3+ ion occupying the [Si8N8] void in the c~1/2 layer, of which the calculated transition energies matching with experiment within 0.1 eV. Such an interstitial Ce3+ site was created as a charge compensator for the aliovalent substitution of Si4+ by Al3+ ions. The red-enhanced LSN:Ce,Al phosphor showed great potentials for improving the optical quality (i.e., color temperature and color rendition) of laser-driven white light.
Voltammetric and Spectroscopic Investigations of L-Cysteine Interactions with Bismuth Ions
Authors: Cheek Graham , Pena Dominik V
Published: December 2020

Bismuth compounds have been widely used for many years as treatments for gastric conditions.1 The electrochemical activity of bismuth suggests that voltammetric studies can provide some insights into interactions of bismuth with naturally occurring ligands found in the digestive system. Of particular interest is L-cysteine, the sulfhydryl side chain of which can interact with bismuth(III) ions.1 Previous work in this laboratory has characterized the electrochemical behavior of L-cysteine in aqueous systems,2 and the present work involves the effect of L-cysteine on the voltammetric behavior of bismuth(III) nitrate, bismuth(III) citrate, and bismuth(III) salicylate. In order to simulate the pH level of gastric contents, studies have been carried out in 0.100 M HCl and 0.100 M HNO3 using the techniques of cyclic voltammetry and square wave voltammetry. Voltammetric scans have been carried out at both glassy carbon and boron-doped diamond electrodes in order to avoid the reduction of protons, which would occur at platinum and gold electrodes. It was found that L-cysteine addition greatly increases the solubility of bismuth(III) nitrate in 0.100 M HNO3, as seen by an increase in the bismuth reduction current and also in the subsequent stripping current of the bismuth deposit. Bismuth(III) salicylate was found to be soluble at the 1 mM level in 0.100 HNO3, and L-cysteine additions produced potential shifts in the voltammetric processes for the bismuth(III) system. These results support the complexation of bismuth(III) salicylate by L-cysteine, even under these very acidic conditions. Similar studies for bismuth(III) citrate were also carried out. Finally, the electrochemical behavior of bismuth(III) nitrate in pH 7.4 MOPS3 buffer was also investigated. It was found that bismuth(III) nitrate (nominal 1.0 mM) was essentially insoluble in this medium; however, additions of L-cysteine produced voltammetric currents typical of the 1 mM concentration level. Initial reduction of bismuth(III) was followed by bismuth stripping peaks at more positive potentials. This behavior supports the complexation of bismuth(III) ion by L-cysteine at pH 7.4. Further evidence of this complexation was found by UV-VIS studies of bismuth(III) nitrate in pH 7.4 MOPS buffer with incremental additions of L-cysteine. An absorbance band at 325 nm appeared as L-cysteine was added, the absorbance of which remained constant after the 1:2 Bi3+: L-cysteine point. These results indicate formation of Bi(Cys)2 under these conditions. As a whole, the present studies indicate the ability of bismuth(III) compounds to interact with L-cysteine over a range of pH levels.

References

1. H. Li, R. Wang, and H. Sun, Acc. Chem. Res., 52, 216 (2019).

2. G. T. Cheek and M. A. Worosz, ECS Trans., 164(12), D707 (2016).

3. C. M. H. Ferreira, I. S. S. Pinto, E. V. Soares, and H. M. V. M Soares, RSC Advances, 5(39), 30989 (2015).
Improvement of Total Capacity of a Lactate/Oxygen Biofuel Cell Based on a Three-Enzyme-Modified Carbon Cloth Electrode
Authors: Tsunaga Motoki , Hoshi Yoshinao , Watanabe Hikari , Shitanda Isao , Mikawa Tsutomu , Tsujimura Seiya , Itagaki Masayuki
Published: December 2020

A biofuel cell using MgO-templated carbon (MgOC) is highly attention as a wearable power source1). A lactate/oxygen biofuel cell, in which lactate oxidase (LOx) is normally used, utilize two-electron oxidation of lactate to pyruvate 2). On the other hand, it is possible to improve the total capacity of the lactate/oxygen biofuel cells by using an enzyme cascadereaction3
).

In the present study, we developed a new biofuel cell that modifies pyruvate decarboxylase (PDC) and acetaldehyde dehydrogenase (ALDH) with LOx in anode. A total of four-electron oxidation reaction can be occurred from lactate to acetic acid via acetaldehyde. In this study, we examined the relationship between the battery capacity and the current density by enzyme cascade in detail.

A carbon cloth was used as anode. 1,2-naphthoquinone, ALDH (20 units), PDC (40 units) and LOx (20 units) were dropped on the anode surface, successively. On the other hand, a MgO-templated carbon (MgOC)-coated carbon cloth was used as cathode. A bilirubin oxidase (BOD, 9 units) was immobilized on the MgOC-coated carbon cloth surface. The performance of the biofuel cell was evaluated by performing chronopotentiometry at a current density of 1 mA cm-2 and 2 mA cm-2. The electrolyte (50 mL) used was 1 mol dm-3 phosphate buffer (pH 7.0) containing 100 mmol dm-3 lactic acid.

Figure 1 shows the chlonopotentiogram of the biofuel cell. It was confirmed that the open-circuit potential of the multi-enzyme-modified biofuel cell was increased compared with that of a conventional lactic acid biofuel cell [2]. The voltage of multi-enzyme-modified biofuel cell was firstly about 0.6 V and then gradually decreased to 0.4 V. Finally, the voltage was drastically dropped at 0 V after 330 s. On the other hand, a voltage of a biofuel cell, which only LOx was modified on the anode, was dropped at 150 s at 1 mA cm-2. The time to reach 0 V was shorter at 2 mA cm-2 at each anode, due to the drastically decrease of the substrate concentration of the electrode surface. From these results, it was indicated that the capacity of the biofuel cell was improved by the enzymatic cascade reactions.

(1) A. Niiyama et al., Journal of Power Sources, 427, (2019), 49.

(2) I. Shitanda et al., Journal of Power Sources, 436, (2019), 226844.

(3) D. Sokic-Lazic et al., Electrochimica Acta, 56, (2011), 10772.

Acknowledgements This work was partially supported by JST-ASTEP Grant Number JPMJTS1513, JSPS Grant Number 17H02162 and Private University Research Branding Project (2017-2019) from Ministry of Education, Culture, Sports, Science and Technology, and Tokyo University of Science Grant for President's Research Promotion．

Figure 1
Microelectrode Arrays for Present and Future Electrophysiological Applications
Authors: Wanzenboeck Heinz , Schuller Patrick , Mika Johann , Taus Philipp , Pribyl Markus
Published: December 2020

In vitro diagnostic devices have highly esteemed platforms for toxicological testing, drug screening and even for theranostics. An extremely promising device type are microstructured devices, often referred to as biochips, that can be coupled with in vitro cell cultures. Employing microfluidic structures devices such as cell-chips and organ-on-a-chip devices have been developed to mimic the microenvironment of the human body. By implementing microelectrodes on the chip it is facile to utilize the benefits of microelectronics - the label-free, non-destructive, permanent real-time measurement of cellular processes.

With electretic cells the action potential of cells can be directly measured, while other non-electrically cells can be measureds via their impedance. We will present devices on both concepts from our research. We will present sophisticated biomedical devices, were used to record the electrophysiological activity the neurite part of nerve cells of in real-time. With an axon isolation device a delicate microfluidics system is combined with microelectrodes inside of microchannels just large enough for axonal and dendritic structures.

Also the biocompatibility of electrode materials is essential, and the relevance of cyclic voltammetry for checking the safe voltage range of microelecrtrodes will be explained with practical examples. Fabrication routes, benefits and limitations of microelectrode arrays. interdigitated electrode sensors and even 3D nanoelectrodedes will be discussed.

An outlook on future devices featuring arrays 3D nanoelectrodes and microstructured guidance structures will be given.
(Invited) Carbon Electrode-Based Electron Transference Enhance Platform Chemical Productions of Live Cell
Authors: Kim Jung Rae , Song Young Eun , Sakuntala Mutyala , Kim Minsoo , Baek Jiyun , Li Shuwei , Khandelwal Himanshu
Published: December 2020

Bacteria is dynamic biocatalyst which is self-regenerating and sustainable in a bioprocess. The respiration and redox state of bacteria are mainly regulated by various external electron acceptors, and significantly influence to the yield/titer of many biosynthesis and biorefinery processes. The cellular redox state is one of the most important factors to control metabolic fluxes and pathways in bioconversion. Conventional strategies for changing the redox state (e.g., the NAD+/NADH ratio) need to provide external oxidants/reductants, such as oxygen, or chemical reductases/oxidases, and carbon source and hydrogen, which are non-sustainable and frequently produce toxic/inhibitory byproducts. In this respect, electrode-based regulation using bioelectrochemical system (BES), has been highlighted for sustainable bioelectricity generation, and in-situ control of bioconversion of substrates such as glycerol, C1 gases etc. The bioelectrochemical regulation of central metabolic fluxes may also trigger gene and enzyme expression. In this study, the increased productivity of the platform chemicals such as 3-hydroxypropionic acid and 1,3-propanediol by using recombinant Klebsiella pneumoniae and E. coli in BES, will be presented as well as recent progress of BES-based bioconversion. The suggested strategy for bacterial redox state regulation not only improves the productivity and yield/titer, but also provides the opportunity for overcoming thermodynamic imbalances in most of bioprocesses. These results could contribute to further improvements in bioprocesses, and could lead to industrial applications for the biorefinery process.
Origins of Capacity Fade and Material Degradation in Ni-Rich NMC Li-Ion Batteries
Authors: Dose Wesley , Morzy Jędrzej K , Mahadevegowda Amoghavarsha , Ducati Caterina , Grey Clare P. , De Volder Michael F. L.
Published: December 2020

Nickel-rich layered oxide cathode materials are promising candidates for automotive lithium-ion batteries due to their low cost and high reversible capacity.1 However, paired with graphite anodes these materials exhibit faster voltage and capacity fading compared to isostructural LiNixMnyCozO2 (NMC) cathodes with lower nickel content.2 In this work we will explore the origins of capacity fade and material degradation in graphite/LiNi0.8Mn0.1Co0.1O2 (NMC811) full cells. With a focus on strategically designed electrochemical protocols (see Fig. 1), the role of several key cycling parameters (e.g. upper cut-off voltage, time at high voltage, phase transitions) on the degradation are decoupled. The aging processes are quantified in terms of the full cell capacity retention, impedance rise, electrode slippage, and NMC cathode deterioration. We find that most full cell capacity loss and impedance rise is caused by increasing the upper cut-off voltage to >4.2 V, with the impedance increase largely driven by concomitant full state-of-charge (SOC) cycling. Time spent at high voltage (voltage holds) has less impact on these parameters. These findings are supported by electron microscopy and spectroscopy experiments (SEM, high-resolution TEM, and STEM-EELS) on cycled electrodes, which show clear evidence for cycle history dependent degradation including particle cracking, shearing, and surface reconstruction.

Figure 1
Crystalline-to-Amorphous Phase Transformations As a Key Ingredient to Enhanced Rate Performance and Cycle Life in Mg- and Na-Ion Battery Anodes: Operando x-Ray Scattering Studies
Authors: Welborn Samuel S. , Wang Lin , Li Manni , Qiu Tian , Foucher Alexandre , Stach Eric A. , Rappe Andrew , Detsi Eric
Published: December 2020

The increasing popularity of Li-ion batteries in new applications such as electric vehicles is expected to cause the key resources (Li, Ni and Co) used in these batteries to become scarce. Alternative battery technologies, including Mg-ion, Na-ion, and metal-air batteries are therefore desirable. In this talk, I will discuss the use of operando wide-angle X-ray scattering (WAXS) to study the crystalline to amorphous phase transformations that are key to the outstanding performance of state-of-the-art alloy-type Mg- and Na-ion anodes. The 1st part of the talk will be on the impact of the crystalline-to-amorphous transformation on batteries cycle life. Here I will discuss our novel self-healing Ga/Mg anode, which holds the current record for cycle performance and rate capability in alloy-type Mg-ion battery anodes, owing to a crystalline Mg2Ga5 to amorphous liquid Ga phase transformation occurring near room temperature, preventing the well-known pulverization issue in alloy-type anodes.[1] The 2nd part of the talk will detail the impact of the crystalline-to-amorphous transformation on the rate capabilities of batteries. Here, I will present our nanoporous Sb/Na system, which transforms from crystalline Na3Sb to crystalline Sb, going through an amorphous intermediate. It will be shown using a combination of WAXS, electrochemical characterization, and computational study based on ab initio grand canonical (aiGCMC) simulations that the amorphous intermediate phase favors high rate Na storage in Sb.[2]

[1] Wang, L., Welborn, S. S., Kumar, H., Li, M., Wang, Z., Shenoy, V. B., Detsi, E.: High‐Rate and Long Cycle‐Life Alloy‐Type Magnesium‐Ion Battery Anode Enabled Through (De)magnesiation‐Induced Near‐Room‐Temperature Solid–Liquid Phase Transformation.
Adv. Energy Mater. 2019, 1902086. https://doi.org/10.1002/aenm.201902086

[2] M. Li, T. Qiu, S. Welborn, A. Foucher, B. Lesel, E. Stach, A. M. Rappe, E. Detsi: Understanding the Fast Kinetics of Sodium Storage in Antimony (unpublished)
Semi in-Situ Measurement of Zincate Ion Concentration Near Zinc Anode Using Background-Oriented Schlieren Technique
Authors: Ito Yasumasa , Liang Xiao , Sakai Yasuhiko , Iwano Koji
Published: December 2020

This study aims to clarify the concentration of zincate ions near the zinc anode upon charging. After preliminary experiments in a mini-channel were conducted to identify the system parameters, galvanostatic charging experiments in a zinc battery cell were conducted at current densities of 20 and 40 mA cm-2. The bulk concentration of zincate ions is set to 0.49 and 0.98 mol L-1. Images near the zinc anode were captured using an optical microscope to calculate the zincate ion concentration distribution through the background oriented Schlieren (BOS) technique. They were taken at an equal time intervals to investigate the transition of the concentration diffusion layer. It was conrmed that the BOS technique enables us to quantitatively measure the zincate ion concentration in zinc anode batteries. The results are consistent with the theoretical expectation. The applied current density basically determines the concentration gradient near the anode surface, although it takes time to reach a steady state. The spatial variance in the zincate ion concentration at the anode surface increases with the distance from equilibrium.
Towards an Understanding of the SEI Formation and Lithium Preferential Plating on Copper
Authors: Menkin Svetlana , O'Keefe Christopher A. , Gunnarsdottir Anna B. , Dey Sunita , Pesci Federico , Shen Zonghao , Aguadero Ainara , Grey Clare P.
Published: December 2020

‘Anode-free’ batteries present a significant advantage due to their substantially higher energy density and ease of assembly in a dry air atmosphere. However, potential safety issues due to lithium (Li) dendrite growth rather than smooth Li metal plating on the Cu current collector, and low cycling coulombic efficiency during their operation are delaying their practical implementation. To understand the interplay between Cu surface chemistry and the morphology of the plated Li, we studied the SEI formation on Cu and the preferential plating of Li using ssNMR, insitu NMR, XPS, ToF-SIMS, SEM and EIS.

A native interphase layer (N-SEI) is formed instantaneously on copper current collectors upon their immersion in LiPF6-based electrolyte. The nature of the N-SEI is affected by the copper interface composition, homogeneity and formation time. In addition to the typical SEI components, it contains CuxO and its reaction products. Parasitic semi-reversible electrochemical reactions were observed with in-situ NMR measurements of Li plating efficiency during the first five cycles. The morphology of the plated lithium is affected by the SEI homogeneity, current density and rest time in the electrolyte before the plating. The preferential plating of Li is governed by the distribution of ionic conducting compounds rather than electronic conducting compounds.[i]

[i] Menkin, Svetlana; O'Keefe, Christopher A.; Gunnarsdottir, Anna B.; Dey, Sunita; Pesci, Federico; Shen, Zonghao; et al. (2020): Towards an Understanding of the SEI Formation and Lithium Preferential Plating on Copper. ChemRxiv. Preprint. https://doi.org/10.26434/chemrxiv.12839792.v1