bluuebunny/crossref_metadata_2025_split huggingface dataset:
Doped ZnO Nanorod Array for Ultra Low NO2 Sensing
Authors: Jain Rishabh , Manthina Venkata , Maric Radenka 
Published: February 2020

NO2 is an important marker in the human breath for asthma whose concentration is proportional to the amount of inflammation in the lungs caused by infections. NO2 is also present in the exhaust of the vehicles and the OSHA recommends no more than 5 ppm NO2 in air. Currently 235 million people are suffering from asthma worldwide and the number is expected to increase drastically owing to the increase in global pollution level and dependence on fossil fuel. Metal oxide semiconductors such ZnO have remarkable sensing properties for, NO2. Sensor response (S) is a function of the resistance of the ZnO on inter-digitated Au electrodes which is given by the following equation:
S = Rair/Rgas , where, Rgas is the resistance of the film in presence of testing analyte and Rair is the resistance of the film in air. The gas detection occurs because of the reaction on the ZnO surface in presence of the NO2 molecule which causes a reduction in electron concentration and hence fluctuation in electrical resistance. This can be explained by the following equation:
NO2 + e- = NO+ + O-
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Here we report synthesis of TiO2 coated ZnO, Mg, Co, and Ag doped as well as undoped thin ZnO nanorod array directly on Au interdigitated electrodes using a low cost, environmentally friendly and large area application two-step chemical bath deposition (CBD) technique [1, 2] for selective detection of ultralow (0.1 ppm) NO2 in humid air at 280 °C. The structure and morphology of the ZnO films prepared by CBD has been probed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The as-prepared doped and undoped ZnO sensors were tested for the detection of NO2 (0.1-5 ppm in simulated breath) in the temperature range of 50-280 ˚C as shown in the figure 1. Characteristics such as sensitivity, selectivity, limit of detection, reproducibility, and stability will be reported. Role of dopants in enhancing the selectivity will be explained. The selectivity for the interfering analytes such as humidity, CO2, NO2, H2 and ammonia will also be investigated. Finally the sensing mechanism will be discussed in detail.
References:
[1] V. Manthina, T. Patel, A.G. Agrios, Number Density and Diameter Control of Chemical Bath Deposition of ZnO Nanorods on FTO by Forced Hydrolysis of Seed Crystals, Journal of the American Ceramic Society, 97 (2014) 1028-1034.
[2] V. Manthina, J.P. Correa Baena, G. Liu, A.G. Agrios, ZnO–TiO2 Nanocomposite Films for High Light Harvesting Efficiency and Fast Electron Transport in Dye-Sensitized Solar Cells, The Journal of Physical Chemistry C, 116 (2012) 23864-23870.

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Li4MeWO6 (Me=Ni, Mn, Co) As Positive Electrode Materials for Li-Ion Batteries
Authors: Kumakura Shinichi , Komaba Shinichi , Kubota Kei 
Published: February 2020

Li-rich layered oxides, Li2MO3 (M = a variety of tetravalent metal(s), typically Mn), have been widely studied as next generation cathode materials for Li ion batteries. Recently, Li4NiTeO6 was reported as a cathode material with 1.5 Li reversible reaction.[1] It has honeycomb structure with ordered arrangement of Te and Ni similar to that of Mn and Li in Li2MO3. The hexavalent Te stabilizes divalent state of Ni ions in the structure. A reversible electrochemical performance based on the redox reaction of Ni2+/Ni4+ was observed. Here, we tried to replace Te for W in Li4NiTeO6. Tungsten is often used as a dopant for positive electrode materials to improve rate performance of Li ion batteries etc. but not popular as a main element building framework because of its heaviness, cost and electrochemical inactivity. In order to understand the influence on the structure and electrochemical properties, we synthesized mainly tungsten-containing materials, Li4MeWO6 (Me=Ni, Mn, Co) expecting hexavalent W6+ ions to stabilize the crystal structure with divalent ions and to improve the diffusion of Li ions during charge and discharge.
Li4MeWO6 was obtained by a conventional solid state reaction with heating and grinding several times. Me used was Ni, Mn, and Co to prepare Li4NiWO6, Li4MnWO6 and Li4Ni0.6Mn0.2Co0.2O6, respectively. XRD pattern of the Li4MeWO6 samples showed a single phase and clear diffraction peaks attributed to honeycomb ordering of Li, Me and W ions in the slab. The electrochemical properties for the Li4MeWO6 materials with different Me composition, were examined using coin-type lithium cells with electrolyte solution of 1M LiPF6/ EC:DMC (1:1).
Figure 1 shows charge/discharge curves of Li4NiWO6, measured with different voltage window at a constant current of 13 mA g-1. In the voltage range of 4.1 - 3.0 V, initial discharge capacity of 83 mAh g-1, corresponding to 1.1 Li extraction from Li4NiWO6 is delivered. Reversible discharge curve and good cycle stability with low polarization are observed in the voltage range, probably on the basis of Ni redox reaction. On the other hand, charging up to 4.9 V results in more than 250 mAh g-1 of charge capacity equal to 3.4 Li extraction suggesting more than 2 electron reaction of Ni2/4+couple. In addition, the polarization is getting increased by increasing upper cut-off charge voltage.
The detailed structural change during charge/discharge and the correlation between Me composition and the electrochemical performance of Li4MeWO6as positive electrode materials in Li cells will be presented.

Reference

[1] M. Sathiya, J. M. Tarascon et al., Chem. Commun, 49, 11376 (2013).

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Novel Asymmetric Capacitors Using Intercalated Metal-Organic Framework Negative Electrodes
Authors: Ogihara Nobuhiro , Ozawa Yuka , Hiruta Osamu , Okuda Chikaaki , Kishida Yoshihiro , Ohba Nobuko 
Published: February 2020

We propose a novel intercalated metal–organic framework (iMOF) electrode material, 2,6-naphthalene dicarboxylate dilithium (2,6-Naph(COOLi)2) as a next-generation negative electrode material for advanced lithium-ion batteries or asymmetric capacitors.
This iMOF material exhibits an operating potential of 0.8 V (vs. Li/Li+) between those of graphitic carbon, operating at 0.1 V, and Li4Ti5O12, operating at 1.55 V. Given the risks of an internal short circuit because of lithium metal deposition in the case of graphitic carbon electrodes and cell-voltage reduction in the case of high-operating-potential Li4Ti5O12 electrodes, this iMOF material possibly represents an advantageous battery design. In addition, because Al can be used as a current collector for this iMOF negative electrode material, whose operating potential is more positive than the potential of the Li–Al alloy reaction (0.4 V), it can potentially be used as a negative electrode material in high-voltage bipolar batteries using only Al current collector.
The proposed electrode material has an organic-inorganic layered structure of p-stacked naphthalene and tetrahedral LiO4 units (Figure 1(a)), and shows a reversible two-electron-transfer Li intercalation (220 mAh g-1) at a flat potential of 0.8 V vs. Li/Li+ with a small polarization (Figure 1(b)). 1, 2 Detailed crystal structure analysis during Li intercalation of this material shows the layered framework to be maintained and its volume change is only 0.33%. This value is much lower than that of the conventional Li-intercalated electrode materials such as graphite (ca. 10%) and Li transition metal oxides (~ 10%). Furthermore, the proposed material exhibits improved regularity of p-stacked packing via self-organization induced by heat treatment under inert atmosphere; this improved packing led to an improvement of reversible capacity as well as to a reduction of internal resistance.3

We examined the device performance of novel asymmetric capacitors comprising the iMOF negative and activated carbon positive electrodes. In this presentation, the possibility of the iMOF as the negative electrodes for asymmetric capacitors will be discussed.
References
1. N. Ogihara, Y. Kishida, T. Ohsuna, K. Miyamoto and N. Ohba, in Meeting Abstracts of 17th International Meeting on Lithium Batteries, p. 320 (2014).
2. N. Ogihara, T. Yasuda, Y. Kishida, T. Ohsuna, K. Miyamoto and N. Ohba, Angew. Chem. Int. Ed., 53, 11467 (2014).
3. T. Yasuda and N. Ogihara, Chem. Commun., 50, 11565 (2014).

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Current Status of National SOFC Projects in Japan
Authors: Kadowaki Masataka 
Published: February 2020

The New Energy and Industrial Technology Development Organization (NEDO) has been conducting technology development and demonstrative research programs related to SOFC, as one of the most important and promising technologies for CO2 reduction and realizing dispersed power sources. One of their achievements was the-first-in-the-world commercialization of SOFC-based combined heat and power (CHP) system “ENE-FARM type S” in 2011.
In June 2014, the Ministry of Economy, Trade and Industry (METI) has compiled a Strategic Road Map for Hydrogen and Fuel Cells. It was established, releasing fuel cells for commercial and industrial use onto the market in 2017 as one of the processes of expanding the use of fuel cell technology. NEDO’s activities on SOFC, including a program “Technology development for promoting SOFC commercialization” , will be overviewed.
Modelling and Prediction of Deformation during Sintering of a Metal Foam Based SOFC (EVOLVE)
Authors: Xu Meng , Masson David , Ryckelynck David , Chesnaud Anthony , Thorel Alain 
Published: February 2020

Stacking of cells in a SOFC stack requires that each element be perfectly flat and deprived, as much as possible, of internal stresses while maintaining their electrochemical capabilities. The EVOLVE concept introduces a metal foam based anode in which the foam plays the role of current collector, gas diffuser and thermo-mechanical deformation buffer. In addition, it means to combine all attractive features of an Electrolyte Supported Cell (ESC), i.e. the flexibility and robustness, with the advantage of an Anode Supported Cell (ASC), the electrical power supplied, in addition to the electrochemical stability under redox cycle in temperature of a Metal Supported Cell (MSC). The use of such innovative anode architecture represents a strategy to improve performances, reliability and durability of SOFCs, along with their tolerance regarding sulphur.
Owing to the very different nature and morphology of the anode components, the deformation during sintering cannot be readily anticipated. Therefore, the global deformation of the cell was modelled and simulated by Finite Element in order to optimize the shaping process. The modelling was achieved considering a phenomenological approach of the anisotropic sintering. Calculations of the deformation include morphological and mechanical characteristics of each layer as well as the dimension of the cell to anticipate any scale effects. The thermo-mechanical parameters of each component were determined experimentally by dilatometry and three-point bending tests operated under conditions identical to those of the sintering. Results provide relevant indications on components composition and morphology, and on the sintering conditions for producing flat and stackable cells.
Steam and Co-Electrolysis Sensitivity Analysis on Ni-YSZ Supported Cells
Authors: Rinaldi Giorgio , Diethelm Stefan , Van herle Jan 
Published: February 2020

The present paper investigates the variation in performances in co-electrolysis of steam/CO2 on SOEC single cells caused by the progressive increase of CO2 inlet concentration and current density.
Steam electrolysis and co-electrolysis were investigated on circular Ni-YSZ supported cells produced by SOLIDpower (“ASC-700” type cells). The thin film electrolyte is constituted by YSZ and the oxygen electrode by LSCF-GDC. The active area corresponds to 12.56 cm2 (2 cm of radius).
The cells were fed with different H2O/CO2 mixtures, while keeping 10% H2 of the inlet molar flow in order to avoid re-oxidation of the Ni-YSZ support.
A sensitivity analysis was performed looking in particular at the effects of inlet gas composition, gas flows and temperature on the performances. I-V characterization and EIS measurements at different current densities were carried out for each sequence.
In steam electrolysis mode, the reference inlet molar flow was equal to 150 Nml/min (90% H20, 10% H2), at 750°C. The I-V curve showed a voltage of 0.861V at OCV, 1.049V at 0.5 A/cm2 and 1.253V at 1 A/cm2. A sensitivity analysis was performed varying the temperature (700°C, 750°C and 800°C), the inlet air flow (100 Nml/min, 300 Nml/min and 500 Nml/min) and the total inlet fuel flow (from 8 to 16 Nml/min/cm2). In this case, the steam conversion factor was kept constant equal to 50% (adjusting the current imposed).
EIS analysis exhibits that ohmic and polarization resistances decrease with current densities lower than 0.4 A/cm2 and then rise with higher values. As expected, the increase of temperature has a positive impact on the performances, while the change of air and fuel flow slightly affects them.
In co-electrolysis mode the CO2 and H2O content was varied, keeping constant the total molar flow and the hydrogen fraction as explained before. As shown in the enclosed image, the area specific resistance (ASR) increases with the CO2 concentration in the mixture and gas transport limitation occurs at lower current densities.
Also in this case a sensitivity analysis was conducted changing the temperature (from 700°C to 800°C) and the resulting EIS plots demonstrate different ongoing processes favored at high current densities. In particular, the reverse water-gas-shift reaction plays an important role on the overall balance of the gas species, and it directly depends on temperature and inlet fuel composition.

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Low Temperature Aqueous Precipitation Synthesis of LiMnPO4 Nano Particles for Li Ion Battery Cathodes
Authors: Vranken Thomas , Damm Hanne , D'Haen Jan , Van Bael Marlies K , Hardy An 
Published: February 2020

LiMnPO4 (LMP) is regarded as a promising material for improved Li ion batteries. It is, like the already commercially applied LiFePO4 (LFP), an olivine cathode material. The main advantage is its higher potential (4.1V vs. 3.5V for LFP, with respect to Li+/Li), resulting in an energy density, about 20% higher than for LFP. The main drawbacks are its low electronic and ionic conductivities (compared to LFP). This results in reduced experimental capacities, especially at elevated (dis)charging rates1. This drawback can be circumvented, by reducing particle sizes to nano dimensions, resulting in shorter Li ion diffusion distances.
Here, we describe an optimized LMP low temperature (100°C) aqueous precipitation synthesis method2, resulting in nanoparticles (NP), with typical sizes of 50-200 nm, of which the reaction time could be significantly reduced, by modifying the base, used for inducing the precipitation. By an in-depth study of several synthesis parameters such as the flow rate, reaction time, temperature, base, … the complexity of this thermodynamically and even kinetically fragile system is emphasized. Our results show that phase pure LMP NP are only obtained in a particular small subset of these parameter values. Outside this range, secondary phases (like Li3PO4, MnHPO4 hydrate and Mn5(HPO4)2(PO4)2.4H2O (hureaulite)) are formed, or LMP is even completely absent.
The figure shows a TEM image of the LMP NP as synthesized after 24 hours at 100°C.
T. Vranken is a Ph.D. fellow of the Research Foundation – Flanders (FWO).
References
(1) Wang, H.; Yang, Y.; Liang, Y.; Cui, L.-F.; Casalongue, H. S.; Li, Y.; Hong, G.; Cui, Y.; Dai, H. Angew. Chemie Int. Ed.
2011, 50, 7364–7368.
(2) Delacourt, C.; Poizot, P.; Morcrette, M.; Tarascon, J.-M.; Masquelier, C. Chem. Mater.
2004, 16, 93–99.

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Understanding and Optimizing Aqueous Viologen Bromide Redox-Enhanced Electrochemical Capacitors
Authors: Evanko Brian , Yoo Seung Joon , Chun Sang-Eun , Vonlanthen David , Wang Xingfeng , Ji Xiulei , Boettcher Shannon Wachter , Stucky Galen 
Published: February 2020

Research in electric double layer capacitors (EDLCs) and rechargeable batteries is converging, producing devices known as pseudocapacitors. Pseudocapacitors store energy electrochemically, utilizing fast and reversible faradaic redox reactions at the interface between high surface area electrodes and an electrolyte. The result is a technology that delivers a long cycle life, high specific power, and moderate specific energy. One frontier in pseudocapacitor research is redox-active electrolytes, which replace the traditional solid redox-active materials with soluble redox couples.
Here we have identified viologen bromide salts as promising aqueous redox-active electrolytes for redox-EDLCs.[i] During charging, Br- is oxidized to Br3
- at the positive electrode and the viologen dication (V2+) is reduced to the stable monocation radical (V+•) at the negative electrode (Figure 1). The system shows unusually high coulombic efficiency and low self-discharge rates for an aqueous redox-supercapacitor. This was initially attributed to strong adsorption of the Br3
- and V+• to the activated carbon electrodes, but we now present a more detailed analysis that confirms the behavior is attributable to two electroprecipitation mechanisms. In these mechanisms, each ion acts as a charge-storing redox couple at one electrode an as a complexing agent at the other electrode. The processes are highly reversible and cells show negligible capacity fade even after 20,000 cycles. The devices use conventional activated carbon electrodes, and because crossover is not a concern and self-discharge is suppressed, a simple cellulose separator is sufficient and ion-selective membranes are not required.
Heptyl viologen devices achieve specific energy densities of 11 Wh/kg (normalized to the mass of both electrodes and electrolyte), significantly higher than commercially available EDLCs (Figure 2). Using methyl viologen increased specific energy to 14 Wh/kg, but at the expense of cycling stability. By studying the operating mechanisms and synthesizing a large series of viologens with different alky substituents we have now identified viologens that deliver both the stability of heptyl viologen and the specific energy of methyl viologen. Finally, a simple electrochemical device model was developed to understand the behavior of the system and predict the maximum theoretically achievable performance (Figure 3). The results model experimental data well and suggest that significant performance improvement is possible, making this technology an exciting candidate for applications like automotive engine start-stop and grid-scale energy storage.

[i] S.-E. Chun, B. Evanko, X. Wang, D. Vonlanthen, X. Ji, G. D. Stucky, and S. W. Boettcher, “Design of aqueous redox-enhanced electrochemical capacitors with high specific energies and slow self-discharge,” Nat. Commun., vol. 6, p. 7818, 2015.

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Cobalt-Nickel Sulfide and Graphite-Coated Iron Carbide As Potential Materials for High-Performance Asymmetric Supercapacitors
Authors: Khani Hadi , Wipf David O 
Published: February 2020

Nanostructured metal sulfides and carbides have recently attracted much attention in many energy storage and conversion applications. In this study, we report the fabrication of an asymmetric supercapacitor with high energy and power density based on carbon fiber@CoNi2S4 nanosheets as a positive electrode and nickel foam@graphite-coated Fe3C nanocomposite as a negative electrode in aqueous KOH electrolyte. CoNi2S4 nanosheets were electrochemically deposited on the carbon fiber cloth via a one-step square-wave pulsed potential technique from a dilute solution of metal ions and thiourea as an ion complexing agent and sulfur source. The high conductivity, surface area, and redox reversibility of the self-support CoNi2S4 nanosheets on carbon fiber make it a promising pseudo-supercapacitor positive electrode. Graphite-coated iron carbide (Fe3C) nanocomposites have been synthesized via a facile two-step heating procedure from the aqueous solution of Fe(III)-citric acid complex. The formation mechanism of Fe3C from the Fe(III)-citric acid complex is investigated by characterizing the starting, intermediate, and final materials by thermogravimetric analysis, X-ray diffraction spectroscopy (XRD), and IR spectroscopy techniques. The morphology and nanostructure of each electrode material are systematically investigated by scanning electron microscopy, transmission electron microscopy, XRD, Raman spectroscopy, and X-ray photoelectron spectroscopy. Cyclic voltammetry was carried out on each individual electrode in the asymmetric supercapacitor assembly to study the charge transfer mechanism. All CVs show two well-defined redox peaks, corresponding to the reversible Faradaic redox reactions of Fe(III)/Fe(II) and CoNi2S4 /CoS2xOH-Ni2S4-2x at the negative and positive supercapacitor electrodes, respectively. The result of galvanostatic charge-discharge tests in a three-electrode system exhibit a high specific capacitance of 582 F g-1 and 2302 F g-1 at 1 A g-1 and 1026 F g-1 and 2180 F g-1 at 20 A g-1 at the negative and positive supercapacitor electrodes, respectively. The optimized asymmetric supercapacitor was reversibly cycled in the high-voltage region of 0-1.6 V and displayed intriguing performances with a specific capacitance of 262 F g−1, high energy density of 94 Wh kg−1, and high power density of 16.1 kW kg−1. Moreover, the supercapacitor exhibits excellent rate capability and retains a high capacity after the hundreds of cycles. These fascinating performances can be attributed to the positive synergistic effects of the two electrodes. These results suggest that carbon fiber@CoNi2S4 nanosheets and nickel foam@graphite-coated Fe3C nanocomposite are very promising for next generation high-performance supercapacitors.
(Invited) Pyrrole-Based Polycyclic Pi-Electron Systems with Various Redox States
Authors: Takase Masayoshi 
Published: February 2020

We have recently reported a series of pyrrole-fused azacoronenes. Due to the interior nitrogen atoms and various resonance forms, all azacoronenes showed multiple oxidation states with different electronic properties. On the basis of these results, a pyrrole-fused azacoronene functionalized with carbonyl groups was designed and synthesized. From the ESR and crystal structure analyses, the azacoronenes revealed spin-delocalized diradical nature in the neutral state. The CV results showed multistep oxidation and reduction peaks. The band gap is very small and the absorption spectra tailed near-infrared region. Pi-extended systems over the previous azacoronenes were also obtained using a similar synthetic strategy. Some crystal structure analyses revealed highly contorted structures. In the presentation, we will report the synthesis, structures, and basic physical properties.
(Invited) Supramolecular Porphyrin Copolymer Directed By Host-Guest Interactions and Metal Coordination
Authors: Haino Takeharu 
Published: February 2020

A bisporphyrin cleft molecule with a trinitrofluorenone moiety assembled to form supramolecular polymers through a head-to-tail host-guest interaction. Bispyridine derivatives work as interchain cross-linkers among the supramolecular polymer chains. The supramolecular networked polymers showed characteristic solution viscosity that revealed the formation of the entangled supramolecular polymers. Viscoelastic spectroscopy established that the supramolecular polymers resulted in well-entangled solutions with associating and networking polymers. Morphological transition of the supramolecular polymers was given by AFM images. The non-cross-linked polymer gave rise to wide-spread thin networks while the cross-linked networks resulted in thicker worm-like nanostructures. The supramolecular networks gelled in 1,1,2,2-tetrachloroethane, and an elastic free-standing film was fabricated with a Young's modulus of 1 GPa.
In this presentation, I will describe the synthesis and characterization of newly developed supramolecular porphyrin polymer, and macroscopic features.
1) Kinjo, K.; Hirao, T.; Kihara, S.-i.; Katsumoto, Y.; Haino, T. Angew. Chem. Int. Ed.
2015, 54, DOI: 10.1002/anie.201508475.

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