bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Gas Leakage on the Performance of Planar Solid Oxide Fuel Cells
Authors: Koomson Samuel , Ebenezer Arthur , Lee ChoongGon 
Published: December 2020

Solid oxide fuel cell (SOFC) is a promising power source with its strong advantage being the use of solid oxide electrolyte. This allows long time operation of the cell without electrolyte depletion. Due to the solid nature of SOFCs, sealing of the cell to the peripheral attachments becomes an issue, especially in planar SOFC type. This defect in gas sealing causes gas-leakage to the outside, as well as, gas-crossover through the peripheral areas of the cell. These leakages lead to a reduction in the open-circuit voltage (OCV) and the overall cell performance. Most previous reports made on gas crossover were only based on H2 crossover through the thin electrolyte membrane. In this work, the performance of a gas-leaked cell was compared with one with a gas-tight sealing. Both cells were 100 cm2 planar SOFCs operated at 750 and supplied with H2 and air gases at the anode and cathode respectively. The cells were supplied by a commercial SOFC producer in South Korea. Electrochemical Impedance Spectroscopy (EIS) and steady-state polarization (SSP) techniques were used in comparing the performance of the cells. An inert gas step addition (ISA) method [1] was also employed in determining quantitatively the partial pressure of water formed at the anode and its resulting internal short current. The ISA was first used to investigate the flow and partial pressure effect on the performance of a molten carbonate fuel cell (MCFC). The method adds nitrogen gas to the anode gas flow and the addition simultaneously increases the reactant gas flow until the added nitrogen arrives at the cell. The nitrogen addition port is placed ca. 5 m ahead of the anode electrode and is supplied through a 1/4-inch stainless tube, thus several seconds are required by the N2 gas to reach the cell. The SSP behavior showed that the OCV and the polarization voltages recorded were higher in the gas-tight cell than in the gas-leaked cell. The impedance spectra, on the other hand, showed a remarkable decrease in the gas-leaked cell and was attributed to the decrease in the water-induced mass transfer resistance of the cell. Through the ISA method, the partial pressure of water formed at the anode as a result of the gas leak was quantitatively determined and was observed to be significantly higher in the case of the gas-leaked cell. Similarly, the computed internal short current was greater in the case of the gas-leaked cell.
[1] C.-G. Lee, B.-S. Kang, H.-K. Seo, H.-C. Lim, J. Electroanal. Chem., 540, 169–188 (2003).
Sm0.5Sr0.5CoO3-Sm0.2Ce0.8O2 Nano Composite Fiber Cathode for Solid Oxide Fuel Cells for Solid Oxide Fuel Cells
Authors: Ju Young-Wan 
Published: December 2020

Solid oxide fuel cells have been considering as an energy conversion device due to their fuel flexibility and high energy conversion efficiency. However, because the high operation temperature of SOFC has caused limitation and instability of the materials, many research groups focus on lowering the operation temperatures [1,2]. In SOFC system, to achieve superior cell performance at low temperature, several issues such as deterioration of electrode’s ionic conductivity and oxygen reduction reaction kinetics should be considered [3,4]. In order to solve these problems, nanocomposite materials introduced hetero interface have been studied on cathode [5-7]. In this study, electrospinning method was used to produce fibrous composite consisting of Sm0.5Sr0.5CoO3-δ (SSC) and Sm0.2Ce0.8O2-δ (SDC). From the XRD and SEM analysis, the lattice strain without the secondary phase occurred and the well-attached interface in microstructure was confirmed. Our designed composite structure as cathode was employed to cause lattice strain that enhances the diffusion of oxygen ion as well as improving the cell performance due to its excellent microstructure.

References

[1] S. C. Singhal, Solid state Ionics, 2002, 152-153, 405.
[2] E. D. Wachsman, K. T. Lee, Science, 2011, 221,935.
[3] J. Nielsen, J. Hjelm, Electrochem. Acta, 2014, 115, 31.
[4] W. H. Kan, A. J. Samson, V. Thangadurai, J. Mater. Chem. A, 2016, 4, 17913.
[5] M. W. Ahn, J. Cho, W. Y. Lee, J. Power Sources, 2019, 434, 226749.
[6] W. Zhang, H. Wang, K. Guan, Z. Wei, X. Zhang, X. Liu, J. Meng, ACS Appl. Mater. Interfaces, 2019, 11, 26830.
[7] B. S. Kang, J. Matsuda, Y. W. Ju, H. H. Kim, T. Ishihara, Nano Energy, 2019, 56, 382.

Figure 1
Infiltration of Metal Catalysts for NH3 Synthesis in Protonic Ceramic Cells
Authors: Dailly Julian , Schmider Daniel 
Published: December 2020

The electrochemical synthesis of green NH3 representes a promising alternative to the conventional Haber-Bosch process, which currently relies on H2 mainly sourced from fossil fuels. Additionally, it compensates for the thermodynamic limitations of the ammonia synthesis reaction via the utilization of high pressures of 150-300 bar, resulting in high energy consumption. The prospect of solid state ammonia synthesis (SSAS) in proton conducting electrolysis cells (PCEC) has been the subject of increased interest recently [1]. It features steam in place of H2 as a reactant and the electrochemical activation of N2 at the hydrogen electrode (cathode) through the use of a catalyst. Possible candidates are metallic Ru or Fe, analogous to the thermocatalytic Haber-Bosch process.
The implementation of the catalyst in the electrochemical cell is critical to the performance of the system. In order to augment the kinetics, high amounts of catalyst near the electrode-electrolyte interface are desired. Therefore, the microstructure of the electrode is of primary interest, as the void fraction of the layer must be large enough to enable a well-distributed deposition of catalyst particles. This may be achieved via the use of a pore-former, e.g. graphite powder, in the wet-route elaboration of the hydrogen electrode (see Fig. 1). However, modifications must not decrease the mechanical properties of the layer.
The effect of various parameters (sintering conditions, thickness of the electrode layer, effect of additives to enhance wettability) on the final electrode structure were investigated, as well as the influence of the infiltration protocol (evacuation time, number of infiltration steps, drying procedure). The findings along with preliminary electrochemical characterizations will be discussed.
[1] V. Kyriakou, I. Garagounis, E. Vasileiou, A. Vourros, M. Stoukides, Progress in the Electrochemical Synthesis of Ammonia, Catalysis Today, 286 (2017) 2-13.

Figure 1
Electrochemical Analysis of Anode Supported PCFC with Pseudo Symmetrical Cell
Authors: Kosuke Yamauchi , Mikami Yuichi , Kuroha Tomohiro , Shiraishi Seigo , Tsuji Yoichiro , Okuyama Yuji 
Published: December 2020

Protonic Ceramic Fuel Cell (PCFC) is expected to be the next-generation fuel cell for its higher energy conversion efficiency and lower operation temperature. BaZrO3 based oxide are potential materials as PCFC electrolyte because they have a high chemical stability under CO2 condition and high proton conduction. Recently, we have developed PCFC using BaZr0.8Yb0.2O3-δ (BZYb) as the electrolyte. The proton conductivity of the BZYb pellet was 1.1×10-2 S/cm at 600℃ and did not form the complex oxide with NiO. The power density of the developed cell (Ni-BaZr0.8Yb0.2O3-δ| BaZr0.8Yb0.2O3-δ| La0.6Sr0.4CoO3-δ) achieved 0.49 W/cm2 at 600℃.To improve the performance of anode supported PCFC, anode supported pseudo symmetrical cell:
Ni-BaZr0.8Yb0.2O3-δ| BaZr0.8Yb0.2O3-δ| Ni
was manufactured and analyzed by impedance spectroscopy under the various conditions and temperatures.The thickness dependence of the ohmic resistance was measured for three types of electrolyte (thickness: 8 μm, 16 μm and 25 μm) under 48%H2-49%N2-3%H2O gas condition at 300-700℃. The conductivity was calculated from the relation between electrolyte thickness and the ohmic resistance, which was 0.35×10-2 S/cm at 600℃. The degradation of proton conductivity occurs due to Ni dissolution. The performance of anode supported PCFC might be improved further if the Ni dissolution to electrolyte can be inhibited.

Figure 1
Plasmonic and Dielectric Metasurfaces for Solid State Lighting
Authors: Murai Shunsuke , Gomez Rivas Jaime 
Published: December 2020

The coupling of layers of light emitting materials to nanostructured surfaces and metasurfaces provides an unique opportunity to tailor the emission, and opens new venues for the design of phosphors in solid-state-lighting. A significant enhancement of the photoluminescence, both spectrally and spatially, have been demonstrated in recent year using metallic metasurfaces.[1] In contrast, the effect of optical absorption by metals on the conversion efficiency is less studied. Here, we investigate the conversion efficiencies for emitter layers deposited on metasurfaces consisting of the periodic arrays of plasmonic and dielectric nanoparticles using an integrating sphere. [2]
Total photoluminescence intensity measured in the integrating sphere (see Figure (a)) is larger for the emitting layer on the silver (Ag) nanoparticle array than the same layer on the titanium dioxide (TiO2) array and on unpatterned flat substrate, manifesting a larger pump or absorption enhancement for the Ag nanoparticle array. The conversion efficiencies are 0.95 and 0.38 for the TiO2 and Ag arrays, respectively (Figure (b)). The excitation wavelength of λ = 532 nm is well below the bandgap of TiO2 and the nanoparticles are virtually transparent, which leads to a conversion efficiency of almost one. For the Ag array, the conversion efficiency is lower due to the intrinsic losses of Ag. The results show that absorption at the excitation wavelengths by the emitter has a critical impact on the conversion efficiency.
The evaluation technique used in this work to quantify the optical absorption by the array, leads to a working recipe to design resonant systems that can be exploited in solid-state-lighting applications.
[1] G. Lozano et al., Light: Sci. Appl.
2 (2013) e66
[2] S. Murai et al., ECS J. Solid State Sci. Technol.
9 (2020) 011614

Figure 1
Electrocatalytic Asymmetric Hydrogenation of α,β-Unsaturated Acids in a Proton Exchange Membrane Reactor with Palladium-Cinchona Catalysts
Authors: Fukazawa Atsushi , Tanaka Kenta , Hashimoto Yasushi , Kobori Yoshihiro , Sato Yasushi , Atobe Mahito 
Published: December 2020

The asymmetric catalytic hydrogenation of the prochiral unsaturated acids is a widely used method for the preparation of optically pure chiral carboxylic acids. These compounds were mainly used in the synthesis of chiral pharmaceuticals. However, a majority of these reactions are homogeneously catalyzed by transition metal complexes which are always expensive and hardly recyclable. Replacement of these highly efficient soluble catalysts by heterogeneous catalytic systems results in several economic and technical advantages. The major advantage of the use of heterogeneous catalysts is to recover the catalyst from the reaction mixtures by simple filtration and recycle. Therefore, the asymmetric hydrogenation of unsaturated acids using heterogeneous catalysts is one of the most challenging topics not only for fundamental scientific research but also for practical applications.
Under these backgrounds, we have demonstrated electrocatalytic asymmetric hydrogenation in a proton exchange membrane (PEM) reactor (Figure 1). This system has several merits such as easy separation and recycle use of catalysts, operation under mild and benign conditions. We found that the use of PEM reactor with cinchona-modified Pd catalyst gave chiral carboxylic acids with excellent current efficiencies and reasonable enantioselectivities in our demonstrations.
The authors gratefully acknowledge support by JST CREST Grant No. JPMJCR18R1, Japan.

Figure 1
Development of an Environmentally Friendly Anodic Fluorination System Based on Bipolar Electrochemistry
Authors: Inagi Shinsuke , Miyamoto Kazuhiro , Sanuki Mokurai , Shida Naoki , Tomita Ikuyoshi , Gotou Akihiro , Yamauchi Akiyoshi , Isogai Tomohiro 
Published: December 2020

Electrochemical fluorination is one of the ideal methods for the selective fluorination of organic compounds under mild safe conditions.1 Recently, Fuchigami and coworkers have demonstrated the electrochemical fluorination of organic compounds using alkali metal fluorides (MF) as a fluorine source and a supporting electrolyte in a poly(ethylene glycol) (PEG)/acetonitrile (MeCN) solution.2 However, to drive electrochemical reactions, the use of a large amount of supporting electrolytes is still necessary.
In this study, to reduce the amount of supporting electrolytes in electrochemical fluorination, we employed a split bipolar electrode (s-BPE) system, in which the redox reactions are driven in a low electrolyte concentration.3 We optimized the electrochemical parameters for the s-BPE system using a U-shaped electrochemical cell and investigated the electrochemical fluorination of organic compounds such as triphenylmethane and derivatives in the presence of potassium fluoride (KF) or cesium fluoride (CsF) as a supporting electrolyte and a fluorine source in a PEG/MeCN solution.4

References

Fuchigami, T.; Inagi, S. Acc. Chem. Res.
2020, 53, 322.

Sawamura, T.; Takahashi, K.; Inagi, S.; Fuchigami, T. Angew. Chem. Int. Ed.
2012, 51, 4413.

Shida, N.; Zhou, Y.; Inagi, S. Acc. Chem. Res.
2019, 52, 2598.

Miyamoto, K.; Nishiyama, H.; Tomita, I.; Inagi, S. ChemElectroChem
2019, 6, 97.
Electro-Oligomerization of Vindoline
Authors: Haque Inam ul 
Published: December 2020

In a break from traditional oncolytic agents based on dimeric combinations [1] of catharanthine and vindoline [2] units, higher cytotoxicity of a designed dimeric vindoline is predicted [3] via its interfacial docking between α- and β-tubulins. Electrosynthesis potentially is a route to higher molecular weight analogs of vindoline. Out of the three dimers resulting from electrochemical oxidation of vindoline [4] only one was characterized; chemical formation of trimeric vindoline [5] has been reported.
Even though vindoline is commonly referred to as a dihydro-indole alkaloid [6], its electrochemistry [7] is dominantly reflective of structurally related anilines. Like electro-polymerization of anilines, our work based on anodic cyclic voltammetry of vindoline suggests formation of vindoline oligomers that readily pass into solution.
References
[1] Byron A. Boon, Dale L. Boger, Triarylaminium Radical Cation Promoted Coupling of Catharanthine with Vindoline: Diastereospecific Synthesis of Anhydrovinblastine and Reaction Scope, J. Am. Chem. Soc., 141 (36) 14349–14355 (2019)
[2] Yang Qu, Michael L. A. E. Easson, Jordan Froese, Razvan Simionescu, Tomas Hudlicky, Vincenzo De Luca, Completion of the seven-step pathway from tabersonine to the anticancer drug precursor vindoline and its assembly in yeast, Proceedings of the National Academy of Sciences, 112 (19) 6224-6229 (2015)
[3] Zhengqiong Zhang, Chengqi Lu, Pei Wang, Aijing Li, Hongbo Zhang, Sichuan Xu, Structural basis and mechanism for vindoline dimers interacting with α,β-tubulin, ACS Omega, 4 (7) 11938-11948 (2019)
[4] Ibro Tabakovic, Katmerka Tabakovic, One pot electrochemical synthesis of 10,10'-bisvindoline by an oxidation-reduction sequence, Tetrahedron Letters, 37 (21) 3659-3662 (1996)
[5] Áron Szigetvári, András Keglevich, Péter Keglevich, Miklós Dékány, László Hazai, Csaba Szántay Jr, A mainly NMR-based structure elucidation of a surprising vindoline trimer with the aid of non-uniform sampled 1H-13C HSQC and HMBC spectra, Structural Chemistry, 30 (3) 795–804 (2019)
[6] Inam ul Haque, Muqaddas Tariq, Nishat Aslam, Hina Saba, Pulsed voltammetry of an Aspidosperma alkaloid: Vindoline, ECS
Meet. Abstr. MA2020-01 2520 (2020). https://doi.org/10.1149/MA2020-01432520mtgabs

[7] Inam ul Haque, ECSarXiv Preprints, in preparation
Highly Selective and Efficient Electrocatalytic Semihydrogenation of Diphenylacetylene to Z-Stilbene Using Pt-Pd Alloy Cathode Catalyst
Authors: Nogami Shuji , Minoshima Juri , Fukazawa Atsushi , Nagasawa Kensaku , Mitsushima Shigenori , Atobe Mahito 
Published: December 2020

The electrical energy can be provided from renewable energy source such as solar and wind, thus making the electrocatalytic hydrogenation process is expected one of important technology to reduce carbon dioxide emission in organic synthesis industry. The selective hydrogenation of alkynes to Z-alkenes is highly important for the construction of numerous valuable compounds, such as bioactive molecules, natural products, flavors, and industrial materials. Although a number of methods for the stereoselective synthesis of Z-alkenes have been developed so far, the Lindlar catalytic semihydrogeneation of alkynes is a long-standing synthetic transformation and still remains the favored system. Howeve
To develop more environmentally benign and efficient semihydrogenation systems, we have demonstrated electrocatalytic hydrogenation of diphenylacetylene (DPA) in a proton exchange membrane (PEM) reactor. 1 In our system, the oxidation of water was employed as an anodic process (Figure 1 (a)).
Especially, in this work, we have investigated systematically influences of catalyst materials such as Pt, Pd, and PtPd alloy for a PEM reactor on the product selectivity for Z-stilbene and partial current density for Z-stilbene formation in the hydrogenation of diphenylacetylene. As a result, PtPd alloy with a composition of Pt1Pd99 was found to be a most suitable catalyst material in order to achieve both high partial current density for Z-stilbene formation and high Z-stilbene selectivity (Figures 1 (b) and (c)). As shown in Figure 1 (b), it was also found that the partial current density for Z-stilbene is much improved by the addition of a small amount of Pt which has the high hydrogenation activity. Moreover, the synergy of Pt electrocatalysis for the formation of adsorbed hydrogen species (Had) (H+ + e− → Had) and Pd catalysis for hydrogenation of DPA (2Had + DPA → Z-stilbene) might be required in order to achieve the high stereoselective formation of Z-stilbene.

Acknowledgement

This work was support by JST CREST Grant No. JPMJCR18R1, Japan. The authors gratefully acknowledge for ISHIFUKU Metal Industry corporation the generous gift for cathode catalysts.

References

1) A. Fukazawa, J. Minoshima, K. Tanaka, Y. Hashimoto, Y. Kobori, Y. Sato, M. Atobe, ACS Sustain. Chem. Eng.
2019, 7, 11050–11055.

Figure 1
Characteristics of Enzyme Electrode Reaction Mediated By Molecular Shuttling
Authors: Masakari Yosuke , Totsuka Naoya , Yoshida Shotaro , Ito Kotaro , Nishizawa Matsuhiko 
Published: December 2020

Enzyme-modified electrodes are core components of bioelectronic devices, such as biosensors and biofuel cells, generating electricity from medical analytes and natural fuel molecules. Most of these devices employ the mediated electron transfer between enzyme active sites and electrode surface via a redox-active molecules called mediators. Conventional mediator molecules are water soluble and freely diffuse into the active site at deep inside of enzyme shell.However, enzymatic fuel cells with diffusing mediators require unwanted complexity component to avoid the cross-talk between anode/cathode systems. In addition, the continuous glucose monitoring (CGM) has begun to be considered for diabetes management. In a CGM sensor, it is necessary that the mediator does not enter the body after detaching from the sensor. These recent backgrounds have made the co-immobilization of enzyme and mediator more important. In this study, we present here a novel enzyme electrode system using glucose dehydrogenase (GDH) and N,N’-diphenyl-p-phenylenediamine (DPPD) as a mediator molecule that can shuttle electrons between the electrode and the reaction center of GDH modified on the electrodes.
The DPPD-adsorbed carbon nanotube modified carbon fabric (CNT/CF) electrode or glassy carbon (GC) electrode were modified by GDHs crosslinked with glutaraldehyde to prepare a GDH-DPPD/CNT/CF electrode or GDH-DPPD/GC electrode. CNT/CF electrode was fabricated according to the method described in the previous study [1].
The performance of GDH-DPPD/CNT/CF electrode was evaluated. The catalytic current appeared from the oxidation potential of DPPD (0.1 V vs. Ag/AgCl) and reached the mA cm-2 order at 0.4 V. Importantly, the catalytic current of GDH-DPPD/GC electrode was maintained at 99% after four replacements of the glucose solution. We proposed the novel mechanism of DPPD-madiated GDH reaction as illustrated in the figure. The oxidized form of DPPD detaches from the carbon electrode and transfers to GDH (i), and reduced with FAD of GDH in the presence of glucose (ii). The reduced DPPD returns to the carbon electrode and is re-oxidized (iii, iv). These reactions (i)-(iv) are repeated for DPPD shuttling-based mediation of the continuous glucose oxidation with GDH-modified electrodes. The several evidences supporting this mechanism will be reported in the presentation.
[1] K. Haneda, et al. Electrochimica Acta., 82, 175-178 (2003).

Figure 1
Non-Invasive and Continuous Monitoring of Differentiation Process into Cardiomyocytes By 2D-SPR Observation
Authors: Shimizu Kei , Shinohara Hiroaki , Suga Minoru 
Published: December 2020

Introduction

Two-dimensional surface plasmon resonance (2D-SPR) measurement method has the advantages of noninvasive and real-time for observation of intracellular reactions. We have already applied this attractive method to monitor cell differentiation noninvasively.
P19CL6, mouse embryonal carcinoma cells were cultured in a medium containing DMSO and 5-azacytidine to induce cardiac differentiation. 2D-SPR observation of the cells was then performed every two days to monitor intracellular refractive index change. The resonance angle of cell regions increased as the differentiation progressed. However, in previous study, cells in differentiation process were once detached from the well plate with trypsin treatment and replated on a gold chip and 2D-SPR measurement was done after one day. Therefore, we considered that the cells might be damaged by trypsin treatment exactly. Here, we aimed to realize noninvasive and continual 2D-SPR observation of the cells during cardiac differentiation process. In this experiment, the sensor chip chamber was covered with a gas permeable membrane and cardiac differentiation process from day 4 to day 14 was continually observed with a high resolution of SPR imager.

Experimental method

In this experiment, P19CL6 cells were cultured on a well plate during the period for formation of embryoid bodies from day 0 to day 4 in the presence of DMSO, and cardiac differentiation was induced on a gold chip from day 4 to day 14 in the presence of DMSO and 5-Azacitidine.The gold sensor chip chamber was covered with a gas permeable membrane to avoid contamination. 2D-SPR observations were carried out every two days to obtain the SPR images of cell regions and to monitor how the resonance angle changes at the cell regions during cardiac differentiation process.

Result and discussion

It was demonstrated that cardiac differentiation of P19CL6 cells on a gold chip was possible and the SPR images of cell regions were continually observed from day 4 to day 14 without contamination. Though the average of the resonance angles at cell regions decreased from day 4 to day 8, but it changed to increase from day 8 to day 12 and reached the maximum on day 12 and day 14. It is considered that intracellular proteins may be reformed to differentiate from embryonic cells into cardiomyocytes from the day 4 to day 8. The cells became cardiomyocyte-like on the day 10 and beating could be observed on a well plate from day 12.
From these results we conclude that continual observation with a SPR imager is very promising method for noninvasive monitoring of cardiac differentiation.

Figure 1