bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Carbon Materials and Electrolytes for Redox Flow Battery By Potential-Sweep Coulometry
Authors: Ohira Akihiro , Negishi Akira , Hozomi Eiji , Sato Yukari 
Published: February 2020

Redox flow batteries (RFB) have been investigated actively now. New redox materials such as metal ions, non-metals, organic molecules are using for the RFB [1-3]. Non-metal RFB are strongly expected by the increasing in needs for the low-cost, safe, and trusted energy storage applications. Since Redox active materials and cell systems have made great progress in recent years, it has been required easy and versatile determination of characteristics of electrode and electrolyte for RFB.
Here we report evaluation of the performance of various types of carbon electrodes and redox behavior with vanadium electrolyte solution by potential-sweep coulometry method. This technique expanded the voltage-step coulometry method which we reported previously [4]. Other electrolytes such as organic redox solution and Ti-Mn were also evaluated by this method [2].
Figure 1 showed the model of the half-cell of the small-scale test cell for potential-sweep coulometry. Electrolyte solution was filled up in the test cell and then stopped, and the current and amount of electricity were measured during for the potential sweep to positive and negative potentials. Figure 2 showed current-potential responses of carbon felt electrode measured in vanadium solution (0.1 M VOSO4/ 3.5 M H2SO4) with different potential sweep rate (0.1, 0.2, and 0.5mV/s). In this case, electrochemical reaction of this carbon felt electrode showed good responses for both charging and discharging process. We also investigated other electrolytes and other carbon felt and paper electrodes.

Figure 1
Linked Anolyte-Catholyte Materials for Redox Flow Battery Applications
Authors: Mann Shane C. , Dumitrascu Adina , Mortimer Nicholas J. , Scott Jessica D. , Henton Daniel R. , Guarr Thomas F. 
Published: February 2020

The emphasis on bringing additional sources of renewable energy online serves to highlight the increasingly critical need for inexpensive and durable means of energy storage. Nonaqueous redox flow batteries (RFBs) may represent an attractive solution, but the cost and efficiency of currently available ion exchange membranes remains problematic. One promising approach to the elimination of membrane crossover issues involves the covalent attachment of an electron acceptor A to an electron donor D via a suitable linker (L) to form a bifunctional compound D-L-A. Such systems would have at least three accessible stable redox states: the “parent” D-L-A, an oxidized form D+-L-A (catholyte), and a reduced form D-L-A-
(anolyte). Since operation of the RFB would involve the production of D-L-A at both anode and cathode, crossover becomes essentially irrelevant.
A number of D-L-A compounds have been prepared using phenothiazine or carbazole donors and pyridinium acceptors (see examples I and II above); several of these exhibit chemically and electrochemically reversible oxidation and reduction, yielding RFB cell voltages over 2 V. Additionally, multiple examples of the related D-L-A-L-D compounds that incorporate acceptors based on various p-phenylene-bridged bis(4-pyridinium) derivatives have also been synthesized and characterized (example III). These latter materials are of particularly interest, displaying 2e- redox activity at nearly 2.4 V with excellent stability.
The electrochemical properties of several representative D-L-A and D-L-A-L-D systems will be described, and recent progress in the development of nonaqueous RFBs employing covalently linked anolyte-catholyte compounds as active materials will be presented.

Figure 1
High-Throughput Electrosynthesis with Flow-through Electrodes Made from Cu Nanowires
Authors: Wiley Benjamin J. , Kim Myung Jun , Yang Feichen 
Published: February 2020

The high surface area per unit volume and large mass-transfer rates offered by three-dimensional porous electrodes have resulted in their use in a wide variety of electrochemical processes.1-4 Several types of porous electrodes are commercially available, including carbon paper, graphite felt, reticulated vitreous carbon (RVC), metal mesh, and metal foam. Metal foam offers relatively high conductivity (1.5x10-5 ohm m) but low specific surface area (<4x104 m-1),5 whereas carbon paper has one of the highest specific surface areas (up to 1.6x105 m-1) but lower conductivity (4.7x10-5 ohm m).6 An improved flow-through electrode would have the electrical conductivity of metals, a surface area greater than carbon paper, and a hydraulic permeability comparable to carbon paper.
This presentation will describe the characteristics of a Cu nanowire electrode that has 15 times more surface area (2.4x106 m­-1) and is 32 times more conductive (1.4x10-6 ohm m) than carbon paper. The improvement in surface area is due to the small diameter of the nanowires relative to carbon fibers. The higher conductivity is due to the intrinsically higher conductivity of Cu, and the fact that the metal nanowires can be sintered together. The porosity of the nanowire electrode is 0.94, but its hydraulic permeability was 89 times lower than carbon paper. For Cu ion reduction, the Cu nanowire electrode can achieve the same single-pass conversion as carbon paper at flow rates up to 1000 times greater under mass transport-limited conditions, and 10 times greater under kinetically limited conditions. We will also report results for the hydrogenation of furfural and for water oxidation. Future work will focus on improving the hydraulic permeability of flow-through electrodes while maintaining a >10x increase in surface area relative to carbon paper.
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Figure 1. Images for Cu nanowire-based electrode and carbon paper.

Figure 1
Electrochemical Activity of Non-Noble Metal Alloy as Catalyst Towards Oxidation of Glycerol in Acidic Media: A Case for the Conceptual Glycerol/Ferric Redox Flow Battery
Authors: Kalu Egwu Eric , Akrasi James , Yeboah Yaw D. 
Published: February 2020

Electro-catalytic oxidation of polyols is a very important path towards the production of high value chemicals. The electro-oxidation of glycerol using precious metals such as Au and Pt has been studied and known to be a source of several end products and has also been utilized in the concept of direct glycerol fuel cells to produce electrical energy additionally [1]. Herein an electro-catalyst comprising a non-noble metal alloy composition, namely nickel, copper and tin on carbon support have been fabricated using the electroless deposition method. The electrochemical activity of the prepared catalysts towards the glycerol oxidation reaction in acidic medium have then been evaluated using physical characterization, electrochemical and chromatographic methods. In the current study, the concept is applied to experimentally demonstrate the working principles of a glycerol-fed redox flow battery using an aqueous solution of a Fe2+/Fe3+ couple as cathode [2]. Constant potential electrolysis coupled with high performance liquid chromatography were used to identify the various compounds generated as a result of the electro-catalytic conversion of glycerol.
References

Li W., Xin L., Zhang Z., Wang Z. (2012) Simultaneous Generation of Mesoxalic Acid and Electricity from Glycerol on a Gold Anode Catalyst in Anion-Exchange Membrane Fuel Cells ChemCatChem Vol 4 1105-1114

J, Kalu E. and Yeboah Y. (2017) A Group Additivity based-thermodynamic analysis of a conceptual glycerol/ferric redox flow battery ECS Transactions, 77 (11) 2005-2010
Quasi-Two-Dimensional β-Ga2O3 based Hetero-Structure Transistors
Authors: Kim Janghyuk , Kim Suhyun , Kim JiHyun 
Published: February 2020

β-Ga2O3 is a wide band gap (4.8 eV) semiconducting material with outstanding chemical and thermal stabilities. As the breakdown voltage of β-Ga2O3 is estimated to be as high as 8 MV/cm, it can be applied to high-power electronics. After β-Ga2O3 thin layers were successfully exfoliated from bulk single crystals by mechanical exfoliation method, the study of high power 2D nano-electronics using β-Ga2O3 received a considerable attention. Though β-Ga2O3 is not a two-dimensional Van der Waals material like graphene and MoS2, a bulk β-Ga2O3 crystal can be easily cleaved into thin nano-flakes in the (100) direction; it has monoclinic structure and the lattice constant is larger along the cleaved plane. Moreover, this ultrathin β-Ga2O3 flakes can be integrated with other 2D materials such as hexagonal boron nitride (h-BN) and transition metal dichalcogenides (TMDs) to make down-scaled, flexible devices. We demonstrated two types of heterostructure devices (MISFETs and JFETs) based on β-Ga2O3 flakes and 2D materials using PDMS stamp method and photolithography.
β-Ga2O3/h-BN hetero-structure based quasi-two-dimensional metal insulator semiconductor field-effect transistors(MISFETs) are fabricated. The h-BN dielectric, which has an extraordinarily flat and clean surface, provides a minimal density of charged impurities at the interface between β-Ga2O3 and h-BN, resulting in excellent device performances. The fabricated MISFETs showed superior drain current modulation with high on/off ratio and low gate leakage current. The double-gating of the fabricated device was demonstrated by biasing both top and bottom gates, achieving the modulation of the threshold voltage.
N-channel β-Ga2O3/WSe2 heterostructure junction field effect transistors (JFETs) are demonstrated with good gate modulation and negligible hysteresis. Tungsten diselenide (WSe2) is mostly known as a stable p-type 2D layered material. The fabricated heterostructure JFETs also showed excellent ambient stability. The successful JFET operation is attributed to Van der Waals junction interface between β-Ga2O3 and WSe2. These heterostructured wide-band-gap nanodevices show a new route toward stable and high-power nanoelectronic devices. The details of the fabrication procedure and results will be presented.
Microstructure Evolution in “Li-Free” Thin Film Solid-State Li-Ion Batteries
Authors: Yang Heng , Citrin Michael A , Xia Xiaoxing , Nieh Simon , Greer Julia R 
Published: February 2020

Li-ion thin film solid state batteries are capable of battery life of more than 10000 cycles1. “Li-free” anodes in solid-state batteries eliminate lithium metal in the manufacturing stage, which could improve energy density, simplify manufacturing process, and lower cost. Attempts to fabricate “Li-free” cells have been challenging because of the concomitant reduction in cycle stability2, 3. Replacing the Cu current collector with metals like Au and Pt, which alloy with Li, shows improvement in cycle stability, probably because it creates a more stable interface4-6. The microstructural changes associated with such improvement, especially at the interfaces, have not been fully understood, hampering future development of all-solid-state “lithium-free” batteries.
We fabricate LiCoO2 (35 µm)/LiPON (4 µm)/M (~15 nm) thin film solid state cells, where M is Cu, Au, or Pt, and study the electrochemical properties and microstructure changes within each thin film during cycling using an in-situ SEM. Figure 1 shows the nucleation of lithium through Cu, Au and Pt current collectors upon charging the cell for 1.5 µAh. In the case of Cu current collector, lithium penetrates the thin Cu layer and preferentially nucleates along the grain boundaries, which is a result of the LiPON solid electrolyte following the contour of the underneath LiCoO2 layer. Assisted by fast lithium diffusion in the alloy, Li-Au and Li-Pt alloy layers probably homogenize the chemical potential across the surface, leading to well-spaced nucleation sites. We further discuss the growth and stripping of lithium at the solid electrolyte/current collector interface and pay close attention to the interactions of the metals with lithium. Finally, we correlate these microstructural details with coulombic efficiency and cycle stability of the solid state cells. These results provide insights into the fundamental electrochemistry and microstructure evolution that occurs in thin film solid-state Li-ion batteries during cycling and may have significant impact on developing “Li-free” solid-state batteries.

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Figure 1
Sodiation Behaviors of 1D Van Der Waals Sb2S3 Nanorods By in-Situ TEM and DFT Calculations
Authors: Yao Shanshan , Cui Jiang , Kim Jang-Kyo 
Published: February 2020

Owing to the abundance, low cost and similar electrochemistry of Na to Li, sodium ion batteries (SIBs) are considered an attractive, low-cost alternative to lithium ion batteries (LIBs) for large-scale energy storage [1]. Among various anode materials for SIBs, antimony trisulfide (Sb2S3) has drawn significant attention due its high theoretical capacity of 946 mAh g−1. However, its underlying sodiation behavior is largely unexplored.
This work [2] reports the sodiation kinetics and the evolution of phase transformation in carbon-coated 1D van der Waals Sb2S3 nanorods based on the in-situ TEM, density functional theory (DFT) calculations and molecular dynamic (MD) simulations. Unique two-step reaction mechanisms of Sb2S3 nanorods are revealed, including Na+ ion intercalation and conversion/alloying reactions, during the first sodiation process. Na+ ions are inserted into the voids between the (Sb4S6)n moieties at an ultrafast speed of 146 nm s−1 upon the first sodiation, leading to amorphization of the crystalline Sb2S3 and negligible volume expansion of ~54 %. The in-situ SAED analysis verifies that the generated NaxSb2S3 intermediate phases are transformed into Na2S and Na3Sb with a trace of Sb crystals during the consecutive conversion/alloying reactions. Upon subsequent desodiation, the Na+ ions extracted from the crystalline sodiated composites transform to amorphous desodiated products.
The DFT calculations attribute such anomalous reaction mechanisms to the unexpectedly low sodium diffusion barrier of Sb2S3 nanorods and the largely improved electronic conductivity arising from the amorphous NaxSb2S3 intermediate phases. These findings on phase transformation routes, dynamics and kinetics occurring during the sodiation/desodiation processes in the Sb2S3 nanostructure will offer insights into better understanding of Na+ ion diffusion mechanisms in van der Waals force stacked materials.

References

[1] J. Cui, S. Yao, J.K. Kim, Recent progress in rational design of anode materials for high-performance Na-ion batteries. Energy Storage Mater., 7, 64–114 (2017).
[2] S. Yao, J. Cui, Z. Lu, Z.L. Xu, L. Qin, J. Huang, Z. Sadighi, F. Ciucci, J.K. Kim, Unveiling the unique phase transformation behavior and sodiation kinetics of 1D van der Waals Sb2S3 Anodes for sodium ion batteries, Adv. Energy Mater., 7, 1602149 (2017).
Electrochemical Ammonia Synthesis in Organic Electrolytes
Authors: Schwalbe Jay , Singh Aayush R. , Nielander Adam C. , McEnaney Joshua M , Jaramillo Thomas F , Nørskov Jens , Cargnello Matteo 
Published: February 2020

In this talk, we present our experimental efforts to increase selectivity in electrochemical ammonia synthesis with electrolyte engineering. Ammonia synthesis is a vital chemical reaction for the modern world. The Haber-Bosh process is routinely credited with supporting somewhere around half of our current population, at a cost of about 1% of the worlds energy consumption. It also requires hydrogen, typically provided through hydrocarbon reforming and is concomitant with centralized infrastructure and distribution. Clearly, this presents an opportunity to develop a process that is not reliant on large capital infrastructure or hydrocarbon derived hydrogen.
One sought after option is a direct electrochemical process. This would enable ammonia to be produced directly using water and electricity from renewable resources. Unfortunately, faradaic efficiencies for ammonia synthesis in aqueous electrolytes are typically observed to be prohibitively low due to the competing hydrogen evolution reaction. Density functional calculations predict that ammonia synthesis will only proceed at potentials more negative than 1 volt, a potential at which most metal surfaces evolve hydrogen rapidly. While, in principle, it may be possible to find a material that activates nitrogen and not protons, we instead focus on changing the electrolyte to reduce HER. According to our simple kinetic model, reducing the availability of protons at the surface will allow nitrogen binding, the presumed rate limiting step, to compete with proton reduction.[1] While there are a number of possible electrolyte systems that may achieve this, we use aprotic, organic electrolytes with alcohols added as proton donors. By using alcohols as a proton donor, we hope to access an additional degree of freedom when engineering the reactivity of the interface. In preliminary measurements, we see faradaic efficiencies approaching 20%. We use both argon and nitrogen-15 labelled control experiments. We see no ammonia produced under argon purge and only labelled ammonia produced when using nitrogen-15 labelled N2.
[1] Singh, A. R., Rohr, B. A., Schwalbe, J. A., Cargnello, M., Chan, K., Jaramillo, T. F., Nørskov, J. K. (2016). ACS Catalysis, 706–709. doi: 10.1021/acscatal.6b03035
Catalyst-Free, Electrolytic Synthesis of Ammonia from Nitrogen and Water By Plasma-Produced Solvated Electrons
Authors: Hawtof Ryan , Ghosh Souvik , Xu Cheyan , Renner Julie N. , Sankaran R. Mohan 
Published: February 2020

Ammonia which is a precursor to fertilizers and food and is one of the most important chemicals in the world is currently synthesized on a large scale by the Haber-Bosch (H-B) process. Recent research has been aimed at developing alternative approaches to synthesizing ammonia to address several issues associated with the H-B process: 1) the very high pressures and high temperatures which lead to enormous capitals costs, 2) the need for hydrogen gas which comes from steam-methane reforming and contributes to high energy costs and environmental impact through greenhouse gas emissions, and 3) the incompatibility with renewable sources of energy that could lower energy costs and environmental impact while also offering more localized, point-of-use sources of ammonia.
Here, we report a hybrid electrochemical system to produce ammonia where one of the metal electrodes is replaced by a plasma (gas discharge). Similar to more typical electrochemical systems, ammonia synthesis is carried out at ambient conditions and only requires electricity. However, the interaction of a plasma and water leads to the formation of solvated electrons, one of the strongest reducing agents known with a reduction potential of ~-2.8 V. Production rates and selectivity (i.e. charge-transfer efficiency) were determined as a function of various process parameters including current, time, and electrolyte composition. We will also discuss a potential reaction mechanism based on the observed results.
Highly Stereoselective Electrocatalytic Semihydrogenation of Alkynes to Z-Alkenes Using a Proton Exchange Membrane Reactor
Authors: Atobe Mahito , Minoshima Juri , Fukazawa Atsushi , Hashimoto Yasushi , Kobori Yoshihiro , Sato Yasushi 
Published: February 2020

Z-alkenes are versatile building blocks in organic synthesis and often found in pharmaceuticals, perfumes, and natural products. Although a number of methods for stereoselective synthesis of Z-alkene have been developed so far, the Lindlar semihydrogeneation of alkynes is a long-standing synthetic transformation and still remains a privileged system. However, it used toxic Pb additive and a large amount of quinolone, and has other limitations such as narrow substrate scope. Therefore, development of a powerful and reliable system for stereoselective semihydrogenation of alkyne to Z-alkene as alternative to the Lindlar catalytic system is still challenging target.
Under these backgrounds, in this work, we have demonstrated electrocatalytic hydrogenation in a proton exchange membrane reactor so called PEM reactor to develop a powerful and reliable stereoselective semihydrogenation system (Figure 1). This system has several merits such as easy separation and recycle use of catalysts, operation under mild and benign conditions, and easy reaction control by applied voltage. Indeed, the use of PEM reactor with Pd catalysts gave Z-alkenes with excellent current efficiencies in our demonstrations.

Figure 1
Paired Electrolysis for Amide Formation Catalyzed By Vitamin B12 Model Complex Under Aerobic Condition
Authors: Shimakoshi Hisashi , Zhongli Luo , Hisaeda Yoshio 
Published: February 2020

Electroorganic synthesis is currently expanding into various interdisciplinary fields because of its versatile application to molecular transformations as well as sustainable and economical advantage. Electroorganic synthesis is especially recognized as green process in synthetic organic chemistry since redox process of substrate is progressed by electric current without chemical reagent and waste after the reaction. Among the various methods in electroorganic synthesis, paired electrolysis is excellent method that electrochemical power is used both on the working electrode and the counter electrode to form synthetic useful compounds.1-4 Here we report the paired electrolysis mediated by vitamin B12 derivative,5 cobalt complex, under aerobic condition to form various amide compounds from trichloromethylated organic compounds and tertiary amines.
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Figure 1