bluuebunny/crossref_metadata_2025 huggingface dataset:
Yttria-Stabilized Zirconia Capping Layer on Pt Cathode By Atomic Layer Deposition
Authors: Yang Byung Chan , Kye Seunghyeon , GO Dohyun , Shin Jeong Woo , Kim Hyong June , Cho Gu Young , An Jihwan
Published: December 2020

Atomic layer deposition (ALD) has the advantage of being able to deposit various materials as nanometer-scale thin films at low temperatures, and to precisely control thickness and doping levels. Due to these advantages, ALD has been applied in various fields including solid oxide fuel cells (SOFCs). SOFC is an echo-friendly next-generation energy conversion device that has high efficiency and fuel-flexibility. However, due to the high operating temperature (1000 ℃) of conventional SOFCs, problems such as thermal degradation and material selection occur. In order to solve this problem, low temperature SOFCs (LT-SOFCs) that can be operated below 500 ℃ are being studied. However, as the operating temperature decreases, oxygen reduction reaction (ORR) at cathodes of SOFCs also slows down. Therefore, engineering cathode surface, where ORR takes place, is important to improve the performance of LT-SOFCs.

In this study, we deposited an ultra-thin film (~ 5nm) yttria-stabilized zirconia (YSZ) overlayer on the Pt cathode surface of LT-SOFC through ALD. In addition, the effect of doping level on the performance and thermal stability of LT-SOFC was studied by varying the cycle ratio of zirconia and yttria. The doping level of the YSZ overlayer was controlled to be 6, 13, 16 and 23 mol%, which were confirmed through XPS analysis. The performance of the cell with 16 mol% -doped YSZ overlayer at 450 ℃ showed the highest maximum power density, which was 70 % higher than that of cell without the overlayer. In addition, the activation resistance, which is mostly from ORR, was also reduced by 27 %. In addition, in the prolonged operation for 5 hours at 450 ° C, it was found that the performance of the cell without the overlayer was reduced by 80 %, while that of the cell with 16 mol%-doped ALD YSZ overlayer was reduced by 40 %. This result shows that the thermal stability was also improved when the ALD YSZ overlayer was deposited.
Improved Mechanical Reliability for Protonic Ceramic Electrochemical Cell Using Alumina Dispersed Electrode Support
Authors: Wu Wei , Bian Wenjuan , Ding Hanping , Ding Dong
Published: December 2020

The protonic ceramic electrochemical cell (PCEC) is increasingly attractive in energy conversion technologies like high temperature steam electrolysis and protonic solid oxide fuel cell. The mechanical durability and robustness of single PCEC, which is critical for technology scale-up and commercialization, is intrinsically lower than the conventional YSZ based oxygen ion conducting cells. In this research, we aim to increase the mechanical reliability of BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) based PCEC by dispersing alumina into the NiO-BZCYYb electrode support. The influences of alumina dispersion on chemical stability, mechanical properties like bending strength (room and high temperature), residual stress, and electrical conductivity of the PCECs with (NiO–BZCYYb)1−x(Al2O3)x (x = 0.1–5 wt%) anode support are measured and analyzed in both oxidized and reduced conditions.
Mitigation of Chromium Poisoning of Ferritic Interconnect of SOFC from Annealed Spinel of CuFe2O4
Authors: Hassan Muhammad Aqib , Mamat Othman Bin
Published: December 2020

Low-temperature solid oxide fuel cells revitalizing usage of metallic interconnects over former ceramic materials. However, chromium poisoning is reducing the performance of ferritic interconnects. To resolve this problem, an attempt to layer metal-oxide coating has been considered. This article encloses the fabrication of optimized slurry composition of CuFe2O4 spinel over Crofer 22 APU and SUS 430 by using the dip-coating technique. These coated samples were dried, heated at 800oC in reducing environment (5% hydrogen and 95% nitrogen), oxidized in the open air and lastly annealed. SEM-EDS results are confirming that spinel protection layer has been fabricated over steel substrates, avoiding any spallation. Annealing reduced thickness of oxide layer from 7.25µm to 4.69µm and improved density of spinel. Spinel coated Crofer 22 APU and SUS 430 formed three and four layers with weight gain rate of 1.65 x 10-12 g2 cm-4.s-1 and 2.597 x 10-12 g2cm-4.s-1 respectively. Decarburization was also observed in both substrates during operational heating and annealing process. The research reveals that the spinel is the promising protective layer for interconnects of SOFC and annealing is the better processing technique for achieving the preferred properties.
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
Investigating the Effects of Lithium Phosphorus Oxynitride Coating on Blended Solid Polymer Electrolytes
Authors: LaCoste Jed Donavan , Li Zhifei , Xu Yun , He Zizhou , Matherne Drew , Zakutayev Andriy , Fei Ling
Published: December 2020

Solid state electrolytes are very promising to enhance the safety of lithium ion batteries. Two classes of solid electrolytes, polymer and ceramic, can be combined to yeild a hybrid electrolyte that can syngergistically combine the properties of both materials. Chemical stability, thermal stability, and high mechanical moduli of ceramaic electrolytes against dendrite penetration can be combined with the flexibility and ease of processing of polymer electrolytes. By laminating a polymer electrolyte with a ceramic electrolyte, the stability of the solid electrolyte is expected to improve against lithium metal, and the ionic conductivity could remain close to the value of the original polymer electrolyte as long as an appropriate thickness of the ceramic eletrolyte is applied. Here we report a bilayered lithium-ion conducting hybrid solid electrolyte consisting of a blended polymer electrolyte (BPE) laminated with a thin layer of the inorganic solid electrolyte lithium phosphorous oxynitride (LiPON). The hybrid system was thoroughly studied. First, we investigated the influence of polymer chain length and lithium salt ratio on the ionic conductivity of the BPE based on poly(ethylene oxide) (PEO) and poly(propylene carbonate) (PPC) with the salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The optimized BPE consisted of 100k molecular weight PEO, 50k molecular weight PPC, and 25(w/w) % LiTFSI, (denoted as PEO100PPC50LiTFSI25) which exhibited an ionic conductivity of 2.11x10-5 S/cm, and the ionic conductivity showed no thermal memory effects as the PEO crystallites were well distrupted by PPC and LiTFSI. Secondly, the effects of LiPON coating on the BPE were evaluated as a function of thickness down to 20 nm. The resulting bilayer structure showed an increase in the voltage window from 5.2 to 5.5V (vs Li/Li+) and thermal activation energies that approached the activation energy of the BPE when thinner LiPON layers were used, resulting in similar ionic conductivities for 30nm LiPON coatings on PEO100PPC50LiTFSI25. Coating BPEs with a thin layer of LiPON is shown to be an effective strategy to improve the long-term stability against lithium.
Perovskite Solar Cell Simulation Using Modeling Software
Authors: Workman Maniell , Chen Zhi David , Musa Sarhan
Published: December 2020

Perovskite Solar cells have shown much promise in a relatively short time. Power conversion efficiencies have increased from 3.8% to 24.2 % in a span of ten years. Perovskite solar cells have attracted much attention in research because of the relatively low cost in manufacturing and production. Current silicon photovoltaic devices are more expensive than conventional fossil fuel. Modelling perovskite solar cells in a simulated environment is critical for data analytics, real fabrication behavior projection, and quantum mechanics of the semiconductor device. This paper presents a SIMULINK model which accurately models the behavior of a solar cell device. The results are compared to a real model. The close correlation between the simulated model and the fabricated devices, demonstrates that this software can be used to simulate a real photovoltaic semiconductor device for research purposes.
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
(Invited) Effects of PrOx and Gd-Doped CeOx Infiltration: Enhancement of Solid Oxide Cell Performance and Stability
Authors: Barnett Scott A , Park Beom-Kyeong , Scipioni Roberto , Lu Matthew Yunching , Grimes Jerren , Chart Yvonne Antonia , Yang Tianrang
Published: December 2020

PrOx-infiltrated oxygen electrodes can yield relatively low polarization resistances even at reduced operating temperature. Similarly, Gd-doped Ceria (GDC) infiltration into Ni-YSZ fuel electrodes has been shown to reduce polarization resistance while also helping to maintain stable electrolysis operation. Here we review the literature on these electrodes and discuss recent results on electrochemical impedance spectroscopy (EIS) studies of PrOx-infiltrated La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and SrTi0.3Fe0.55Co0.15O3 (STFC) oxygen electrodes and GDC-infiltrated Ni-YSZ. Physically-based equivalent circuit models are developed using the distribution of relaxation times method and used to fit the symmetric cell EIS data, comparing PrOx- and GDC-infiltrated electrodes with un-infiltrated electrodes. The results suggest that PrOx improves oxygen dissociative adsorption/desorption, oxygen surface exchange, and transport of oxygen in the perovskites; while GDC reduces the reaction resistance associated with three-phase boundaries and improves oxygen transport in Ni-YSZ. Full cells employing the PrOx-infiltrated STFC and Ni-YSZ:GDC electrodes achieve high performance (e.g. fuel cell power density nearly 3 W/cm2 at 750 oC and > 1 W/cm2 at 600 oC; and electrolysis current density at 1.3 V of nearly 4 A/cm2 at 750 oC), while exhibiting promising stability. Combining the equivalent circuit models from the symmetric cell data for each electrode provides a detailed explanation and fit of the full cell EIS results.
Strongly Coupled Metal/Oxide Heterointerface for Efficient Ammonia Electrosynthesis at Mild Condition
Authors: Hua Bin , Li Meng , Ding Dong
Published: December 2020

Ammonia is one of the most highly produced inorganic chemicals, but its synthesis is challenging and is heavily dependent on the use of nonrenewable petroleum resources. The artificial nitrogen fixation in industry, i.e., the Haber–Bosch process, consumes 1~2% of the world's energy supply while releases 3% of the world's carbon emissions. Therefore, researchers have been searching for alternative methods to sustainably synthesize ammonia in an environmentally begin way. The electrochemical synthesis of ammonia using renewable energy under mild conditions is promising but challenging. An efficient electrochemical ammonia synthesis process requires active catalysts, as well as suitable electrode and cell design. In this presentation, we report our research achievements on the development of strongly coupled metal/oxide heterointerface as well as its integration into a protonic ceramic electrolyzer for ammonia production. The outcome of this research has the potential to contribute to establishing a globally competitive U.S. industry and is well aligned with the U.S. DOE’s goals of growing the energy economy, improving energy efficiency, and innovating clean energy sources.
Luminescence Studies of Pyrochlore Metal Oxide Nanomaterials
Authors: MAO Yuanbing
Published: December 2020

Designing lanthanide doped luminescent materials especially nanomaterials with multifunctional applications is highly challenging and demanding. The chemistry and structure of the host materials for lanthanide ions are critical in the selection of known phosphors and in the discovery of new phosphor materials for being used for the applications. Materials with A2M2O7 pyrochlore composition recently have displayed a variety of advanced applications in solid oxide fuel cells, photocatalysis, thermographic phosphor, thermal barrier coating, X-ray scintillator, photoluminescence, and nuclear waste host, etc. In the past few years, we have focused on the studies of pyrochlore AIII
2MIV
2O7 nanoparticles (NPs, where A = trivalent heavy element ions of both lanthanides and actinides, and M = Zr4+, Hf4+, etc.) useful for solid-state lighting, X-ray scintillators, thermometry, and bioimaging. We have achieved substantial tunability of their particle size, crystal phase, and more importantly, luminescence properties. We have gained a clear understanding of the influences of synthesis conditions, particle morphology and composition on their photoluminescence and radioluminescence. The tunable luminescence properties of these lanthanide doped pyrochlore NPs indicate their great application potentials in solid-state lighting and multicolor luminescence devices.
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
Welcome Remarks - K01: New Developments in Synthetic and Mechanistic Organic Electrochemistry: In Memory of Junichi Yoshida
Authors: Atobe Mahito
Published: December 2020

Welcome to K01: New Developments in Synthetic and Mechanistic Organic Electrochemistry: In Memory of Junichi Yoshida! Take a moment to listen to welcome remarks from the lead organizer, Mahito Atobe.
DNA ‘Velcro’ to Interface Electron Transfer-Competent Cells with Electrodes
Authors: Furst Ariel L
Published: December 2020

Microbial fuel cells offer promising clean energy technology by degrading wastewater components while generating electricity. Yet, there remain challenges with the broad implementation of these systems, often due to variations in the interactions between microbes and electrode surfaces. A key challenge with cells interacting with inorganic surfaces is maintaining specificity in the placement of cells while enabling electron transfer between the cells and the surface. DNA can both self-recognize and act as a molecular wire. By using the inherent specificity of DNA hybridization as a biological ‘Velcro,’ we have captured and quantified non-adherent cells, including the electron transfer-proficient organism Shewanella oneidensis. When immobilized on electrodes with this method, Shewanella maintain their electron transfer capabilities prior to biofilm formation. We attribute this ability, at least in part, to the conductivity of DNA. Our DNA ‘Velcro’ method to interface cells with electrodes has significantly improved the ease of fabrication and generation of current from microbe-modified electrodes.
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
Electrochemical Activation of Small Molecules with Microbial Catalysts
Authors: Liu Chong
Published: December 2020

Microorganisms are powerful biocatalysts that can fulfill chanllagning chemical reactions at ambient conditions. Interfacing microorganisms with electrochemistry offers a viable route to achieve a distributed electristry-driven chemical synthesis with renewable energy. Here we describe our progress at the microibal-materials interface for electrochemical reduction of CO2 and N2, with advanced design of nanomaterials.
Systematic Analysis of Oxygen Functional Groups and Graphitic Defects on Vanadium Flow Battery Electrodes
Authors: Radinger Hannes , Ghamlouche Ahmad , Scheiba Frieder , Ehrenberg Helmut
Published: December 2020

For many electrochemical applications in the energy sector such as batteries, electrolyzers, or supercapacitors, surface-active oxygen functional groups (OFGs) are considered essential. This has sparked a lot of scientific as well as industrial activities for instance in the domain of vanadium redox flow batteries, focusing on the optimization of graphite electrodes by various oxidative treatments. The introduced OFGs are considered to catalyze the vanadium redox reactions effectively. However, these studies often disregard that the harsh attack of the surface also leads to an increase of graphitic edge sites which may also contribute to the observed catalytic activity. In a previous study, we could demonstrate that the relative amount of OFGs is less important for the catalysis than the electrochemical stability of structural defects. Further, the initial surface composition and defect structure was altered significantly, which complicates a prediction of the performance based on starting OFGs. Therefore, a more systematic approach is taken to analyze the influence of OFGs and defects on the electrocatalytic activity. To separate the effect of OFGs and defects we took the reverse approach by thermally deoxygenating two different kinds of graphitic electrodes; a pristine one with a low quantity of defects and oxygen species, and a thermally activated one with a high amount, respectively. By varying the stripping temperature and saturating resulting dangling bonds with hydrogen, specific OFGs were removed prior to electrochemical cycling experiments. Subsequently, the electronic and defect structure of the samples was analyzed by X-Ray photoelectron and Raman spectroscopy. Cyclic voltammetry and impedance spectroscopy were used to study the electrochemical performance. Our results suggest that the initial amount or kind of OFG has no beneficial effect on the catalysis of the vanadium redox reactions. The pristine graphite felt exhibited even higher half-cell activity after the thermal treatment, which is attributed to an increase of graphitic edge sites by the removal of carbon atoms and OFGs. For the activated felt no remarkable change in activity was observed after stripping due to its already initially quite high amount of defects. However, the deoxygenated samples showed a decrease of the charge-transfer resistance during reductive, and an increase during oxidative cycling. The evolution of OFGs and defects after electrolytic immersion and polarization experiments was investigated. Similarly, a pristine and a deoxygenated electrode have been subjected to long-term cycling, studying the evolution of the charge-transfer resistance, the chemical composition, and the microstructure. The results of our study disprove the universal opinion about the role of carbonaceous OFGs for the catalysis of the vanadium redox reactions. It is much rather the degree of disorder that is responsible for the activity of the electrode.

Figure 1
Sheet Type All-Solid-State Batteries with Sulfide Electrolyte
Authors: KIM KyungSu , Kang Seulki , Cho Woosuk , Park Kern-Ho , Jeong Goojin , Yu Ji-Sang
Published: December 2020

Lithium ion batteries have received great attention due to emerging electric vehicle market to suppress global climate change issues. Batteries with higher energy density is required to improve driving distance of electric vehicle. As energy density increase, safety become more important point to prevent unexpected accident. Safety issues of current lithium ion battery system mainly comes from the oxide cathode and flammable organic electrolyte. All solid state batteries with non-flammable inorganic solid electrolytes come into the limelight due to its potential for securing higher energy density and safe characteristics over current lithium ion battery system.

In this study, composite electrode sheet and cell fabrication technology was examined by slurry mixing coating technique. Cathode electrode sheets were obtained by coating slurries consisting of LiNi0.8Co0.1Mn0.1O2 as the active material, an argyrodite structure Li6PS5Cl solid electrolyte, conductive carbon, butadiene-based binder with solvent on carbon coated aluminum foil as the current collector. Homogeneous mixing and coating conditions were examined by controlling composition, kinds of binder in order to achieve optimal conduction pathway of lithium ion and electron. All solid state batteries were fabricated and evaluated both half-cell and full-cell type. Electrochemical tests were investigated and the detailed results will be discussed in this presentation.
Introducing Electromagnetic Battery Sensors, with Unprecedented Performance
Authors: Roumi Mahshid , Roumi Farshid
Published: December 2020

The chemistry of batteries have been improving constantly for the past century; however, the battery monitoring and thus management has not seen any real improvements since decades ago.

Internal shorts cost manufacturing companies millions of dollars each year. This is because it takes days and weeks to screen for cells with potential internal shorts. If undetected, the faulty cells in the field can cause millions of dollars in damages. Therefore, significantly increasing the speed of detection may double the profit of the manufacturing company. Internal shorts is also one of the major challenges of fast charging batteries. Fast charging can lead to hard- micro shorts that can result in battery failure and thermal runaway.

We have developed a completely new class of battery monitoring and screening sensors, PES™, first demonstrated by our team at Caltech in 2014. PES™ is an electromagnetic-based battery sensing platform, based on an extension of electrochemical impedance spectroscopy (EIS) to EM induction from an electrochemical system.

Conventional battery testing is primarily based on voltage, impedance, and/or temperature monitoring, which generally register issues only after significant internal changes to the condition of the battery have occurred. PES™ detects minor changes in the electric field itself, and can identify small internal shorts and structural variations in the battery well before they register in voltage/temperature-based reading fluctuations.

We have successfully demonstrated that it can detect gradually developing internal shorts, as large as 3300 ohms, which are extremely hard to detect by conventional voltage sensors. To significantly reduce the risk of failure and fire, the sensor should be an important part of any large Li-ion battery or any future Li-metal batteries. This class of sensors based on electromagnetism as opposed to the conventional voltage, current or temperature monitoring opens the door to many new applications, resulting in much higher utilization of batteries.

Figure 1