bluuebunny/crossref_metadata_2025_split huggingface dataset:
Strong Photoluminescence and Thermal Stability of Eu(III) Coordination Polymers with Thiophene-Based Bridge
Authors: Hirai Yuichi , Nakanishi Takayuki , Kitagawa Yuichi , Fushimi Koji , Hasegawa Yasuchika 
Published: February 2020

Lanthanide coordination compounds, composed of lanthanide ions (Ln(III)) and specific organic ligands, are widely known to show sharp and strong emission due to the nature of f-f transition in lanthanide ions.1They are promising candidates for LEDs, chemical sensors, and solar cells applications. In order to compensate the small absorption coefficients of Ln(III) ions, various types of antenna ligands have been developed to harvest and transfer the energy from the light source to the Ln(III) ions through ligand to metal energy transfer upon excitation.
Our group have previously reported that the Ln(III) coordination polymers with phenylene-based bridging ligands show thermal stability above 300˚C due to the intermolecular CH/F and CH/π interactions.2

In this presentation, we demonstrate the design and synthesis of novel Ln(III) coordination polymers composed of Eu(III) ions, beta-diketonates, and thiophene-based bridging ligands in order to estabilish both high emission quantum yields and thermal stability. The decomposition temperature of these coordination polymers are estimated to be above 300˚C. According to the single crystal X-ray analyses, multiple intermolecular CH/F interactions are observed between single polymer chains because of the zig-zag coordination structure. They also exhibit intense red emission which is detectable to the naked eye under daylight. Emission spectra, quantum yields (Φ
total,
Φ

Ln), and lifetimes (τ
obs) are also measured to estimate the photophysical parameters such as radiative and non-radiative constants (k
r and k
nr, respectively).
References
1. J.C.G. Bünzli, C. Piguet, Chem. Soc. Rev., 34, 2005, 1048.
2. K. Miyata, T. Ohba, A. Kobayashi, M. Kato, T. Nakanishi, K. Fushimi, Y. Hasegawa, ChemPlusChem, 77, 2012, 277.
High Photostability of Fluorescent InP/ZnS Quantum Dots Embedded in Tmas-Derived Silica
Authors: Watanabe Taichi , Wada Chikako , Iso Yoshiki , Isobe Tetsuhiko , Sasaki Hirokazu 
Published: February 2020

InP/ZnS core/shell quantum dot (QD) is suited to application to white LEDs, but the photoluminescence (PL) intensity decreases under continuous photo-excitation. This QD degradation is attributed to photo-oxidation, so it is needed to avoid contact between QD and air. In this study, we embedded InP/ZnS core/shell QD into tetramethylammonium silicate (TMAS)-derived silica monolith to improve its photostability.
Hydrophilization of InP/ZnS QD capped with 1-dodecanethiol was needed for embedding them into silica. For ligand exchange, 3-mercaptopropionic acid (MPA) was injected into a colloidal solution of InP/ZnS QD capped with 1-dodecanethiol at 240 °C. Then, InP/ZnS QD capped with MPA was dispersed in TMAS aqueous solution. Methyl L-(−)-lactate was added to the solution for gelation. Monolithic InP/ZnS@TMAS-derived silica composite was obtained after drying. InP/ZnS@polymethylmethacrylate (PMMA) composite was also prepared to compare with InP/ZnS@TMAS-derived silica composite in terms of photostability.
QD-silica composite exhibited high transparency due to homogeneous dispersion of InP/ZnS QD capped with MPA in TMAS aqueous solution. Carboxyl group of MPA is deprotonated under basic conditions, so InP/ZnS QD capped with MPA possesses negative charge in the basic TMAS aqueous solution. This causes electrostatic repulsion between QD and silicate anion, and hence high dispersibility of InP/ZnS QD capped with MPA in TMAS aqueous solution. The emission peak of InP/ZnS@TMAS-derived silica composite under 400 nm excitation was observed at 543 nm. To evaluate photostability, we examined PL intensity after continuous excitation for 180 min. PL intensity of InP/ZnS QD capped with MPA after continuous excitation was only 25% of the initial PL intensity. On the other hand, InP/ZnS@TMAS-derived silica composite retained 90% of the initial PL intensity. This result means protecting QD against air achieves high photostability. Furthermore, InP/ZnS@TMAS-derived silica composite was more photostable than InP/ZnS@PMMA composite, which retained 68% of the initial PL intensity. This indicates that the gas-barrier property of TMAS-derived silica is higher than that of PMMA.
Comparison of Voltammetric Techniques for the Electroanalysis of Dissolved Solids and Gases in Water, Acetonitrile and Room Temperature Ionic Liquids (RTILs): Unusual Behaviour for Gases
Authors: Hussain Ghulam , Silvester Debbie S. 
Published: February 2020

Square wave voltammetry (SWV) and differential pulse voltammetry (DPV) are commonly used in electroanalysis, typically in aqueous solvents, as they are usually an order of magnitude more sensitive than linear sweep voltammetry (LSV)/cyclic voltammetry (CV), (e.g. detection limits as low as nanomolar are possible using SWV). These more sensitive techniques are often applied in the development of electrochemical sensors and biosensors over the last ten years due to the negligible capacitive current compared to faradaic current (in protic solvents).1,2 Over the last two decades there has been great attention focused on the improvement of electrochemical gas sensors to monitor toxic gases using amperometric gas sensors (AGSs), which typically employ water/sulphuric acid electrolytes as solvents. Room temperature ionic liquids (RTILs) have been attracting great attention3 as replacement electrolytes in AGSs due to their unique physical properties such as low volatility and negligible vapor pressure, wide electrochemical windows, high ionic conductivity, high chemical and thermal stability and their ability to dissolve a wide range of gases. To the best of our knowledge, there are limited studies on the sensitivity of SWV, DPV and LSV for the sensing of gaseous analytes in RTIL solvents. In this presentation, a comparison of three different electrochemical techniques (SWV, DPV and LSV) will be employed for two gases (ammonia and oxygen) in RTILs. As a control, oxygen gas will also be studied in acetonitrile and water solvents, and dissolved solid analytes are also studied (K3Fe(CN)6in water, ferrocene in acetonitrile and ferrocene in RTILs). For all dissolved solid analytes, SWV gave the highest current response compared to DPV and LSV, respectively. For dissolved gases, the behavior was different. For oxygen, LSV gave larger currents (although relatively comparable) to SWV, with DPV giving the lowest currents. For ammonia, LSV was far superior to both SWV and DPV and was consistent throughout eight different RTIL solvents. This suggests that the generally accepted methods for low concentration analyte detection may not apply for dissolved gases.
References:
(1) Carl H. Hamann, A. H., Wolf Vielstich. Electrochemistry, 2nd, Completely Revised and Updated Edition; Wiley-VCH, Weinheim, 2007, p 550.
(2) Chen, A.; Shah, B. Analytical Methods
2013, 5, 2158-2173.
(3) Buzzeo, M. C.; Hardacre, C.; Compton, R. G. Analytical Chemistry
2004, 76, 4583-4588.
Molybdenum-Based Nanomaterials As High Efficient Electrocatalysts for HER
Authors: Wu Zexing , Wang Jie , Xin Huolin L. , Wang Deli 
Published: February 2020

a, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P.R. China
b, Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA
* Email: wangdl81125@hust.edu.cn
Electrochemical hydrogen evolution reaction (HER) as an efficient and eco-environmental approach to produce hydrogen has attracted tremendous attention1. Currently, the most efficient catalysts for HER are platinum group metals (e.g. Pt). However, the scarcity and high cost of precious metals limit their large-scale applications2. Therefore, it is of great importance to explore highly active catalysts for HER based on earth-abundant materials for the large scale hydrogen generation in both acid and alkaline media3.
Here, carbon supported different molybdenum-based materials (MoP, MoS2, Mo2C) have been systematically synthesized via a simple solvothermal-high temperature treatment method. Different morphologies were obtained such as few layers and nanoparticles structures (Figure 1a and b). Electrochemical tests reveal that the prepared molybdenum- based electrocatalysts exhibit excellent HER performance in both acid and alkaline electrolytes (Figure 1c and d). This could be attributed to the excellent conductivity and the exposed substantial active sites for the nano-structure. In acid medium, carbon supported MoP exhibits the best catalytic activity for HER with an overpotential of 136 mV at a current density of 10 mA cm-2. While Mo2C-C possess the most predominant catalytic performance in alkaline medium compared with MoP and MoS2 with an overpotential of 149 mV. Unexpectedly, in the present work, carbon supported MoS2 possess outstanding catalytic activity in both acid and basic electrolytes which is not common for molybdenum chalcogenides reported. This probably due to the low conductivity and strongly layer numbers dependent on the the active sites. Based on the facile preparation method and excellent electrocatalytic activities, this work will open a novelty avenue to prepare earth abundant based catalysts for energy conversion and storage.
Figure 1. TEM images of MoS2-C (a) and Mo2C-C (b). LSVs of molybdenum compounds in 0.5 M H2SO4(c) and 1 M KOH (d).
Acknowledgements
This work was supported by the National Natural Science Foundation (21306060, 21573083), the Program for New Century Excellent Talents in Universities of China (NCET-13-0237), the Doctoral Fund of Ministry of Education of China (20130142120039).
References
1. Y. Jiao, Y. Zheng, M. Jaroniec and S. Z. Qiao, Chem. Soc.
Rev., 2015, 44, 2060-2086.
2. H. Wang, D. Kong, P. Johanes, J. J. Cha, G. Zheng, K. Yan,
N. Liu and Y. Cui, Nano Lett., 2013, 13, 3426-3433.
3. J. Tian, Q. Liu, A. M. Asiri and X. Sun, J. Am. Chem. Soc.,
2014, 136, 7587-7590.

Figure 1
Influence of Cathode Potential on Ti Electrodeposition in Molten Fluoride
Authors: Nishikawa Kazuyoshi , Humiya Sawada , Morishige Taiki , Takenaka Toshihide 
Published: February 2020

INTRODUCTION
An innovative process of Ti metal production which replaces the Kroll process is desired. Some new production processes have been proposed. Our group has been studying the direct electrolytic smelting of liquid Ti metal above the melting point of Ti in molten fluoride. In our previous reasearches, the cathodic behaviors of Ti ion were investigated in CaF2-MgF2-CaO-TiO2melt above 1373K, and it was shown that Ti metal could be obtained under a suitable condition.In this study, the influence of the cathode potential on Ti electrodeposition has been studied in molten fluoride.
EXPERIMENTAL
The apparatus is schematically shown in Fig.1. A eutectic mixture of CaF2-MgF2 was used, and CaO and TiO2 were added. The molar ratio of CaO to TiO2 in melt was fixed as 1.5 in this study. The mixture was fused at the 1573~1773K.Cyclic voltammetry was applied to clarify the cathodic reaction. A Mo wire (f1mm) was used as a working electrode, and it was covered with a BN sheath except for 3~4mm of its end. A graphite rod (f5mm) was used as a counter electrode. Another Mo wire was used as a quasi-reference electrode. The potential of the quasi-reference-electrode was calibrated by the zero-current potential by Mg deposition and dissolution. Based on the results of the cyclic voltammetry, potentio-static electrolysis was performed to obtain the electrodeposit. The electrodeposit was analyzed by XRD and SEM-EDX.
RESULTS and DISCUSSION
Fig. 2 shows typical cyclic voltammograms in the baths with and without CaO and TiO2 at 1573K.The current density below 0.8V in the bath with CaO and TiO2 was larger than in comparison with that without CaO and TiO2, which suggested that Ti reduction occurred 0.8V.Electrodeposits were obtained by potentio-static electrolysis performed below 0.7V. Ti metal was detected in the deposit obtained at 0.2~0.4V by XRD, while only Ti oxides were detected in the deposit at 0.5~0.7V.
Small particles containing Ti were found in the electrodeposit by SEM obvervation. Fig.3 shows the relationship between the cathode potential and the atomic ratio of O to Ti of the particles by EDX. These results clearly indicate that the particles obtained above 0.5V were Ti oxides and that at 0.4V was Ti metal, which agrees well with the results by XRD. The Ti metal particle was not found in the deposits obtained below 0.3V. Because Ti metal was detected in these deposits by XRD, Ti metal particles were too small to be found by SEM observation.
It was confirmed that the cathodic current below 0.8V in CaF2-MgF2-CaO-TiO2corresponded to the Ti reduction; a Ti ion was partially reduced at 0.5~0.8V, and Ti metal was obtained below 0.4V.
AKNOWLEDGMENT
This study was supported by the New Energy and Industrial Technology Development Organization (NEDO) under the “Innovative Structure Materials Project (Future Pioneering Projects)”, and by Kansai University Grant- in Aid for Progress of research in graduate course, 2011.

Figure 1
Ionic Liquid Polymer Electrolyte Based on Bis(fluorosulfonyl)Amide for Sodium Secondary Batteries
Authors: Ab Rani Mohd Azri , Matsumoto Kazuhiko , Hagiwara Rika 
Published: February 2020

The development of non-flammable electrolytes has been extensively studied to reduce the drawbacks caused from organic solvents. In this study we have successfully demonstrated the use of Ionic Liquid Polymer Electrolyte (ILPE) as a separator for sodium ion battery by using polyvinyl chloride (PVC), in combination with the previously reported ionic liquid electrolyte, Na[FSA]-[C2C1im][FSA] (FSA = bis-(fluorosulfonyl)amide and C2C1im = 1-ethy-3-methylimidazolium)1. The ILPE was prepared by casting method in which PVC acts as a host polymer. The different ratio of [C2C1im][FSA] was added into the THF solution of PVC/NaFSA (1:1). The highest ionic conductivity was achieved with addition of 42.9% ionic liquid into the system which resulted in 1.49 mS/cm at 25 °C. The deposition and dissolution of Na metal has been observed around 0 V vs Na/Na+ by cyclic voltammetry. The reversible capacity of 92 mA g-1 was obtained at 363 K for a Na2FeP2O7 positive electrode in the Na/PVC-Na[FSA]-[C2C1im][FSA]/ Na2FeP2O7-cell (theoretical value is 97 mA g-1). This result suggests that the ILPE is a promising separator for sodium secondary battery where safety and cost are main concern.
1. Matsumoto, K.; Hosokawa, T.; Nohira, T.; Hagiwara, R.; Fukunaga, A.; Numata, K.; Itani, E.; Sakai, S.; Nitta, K.; Inazawa, S., The Na[FSA]–[C2C1im][FSA] (C2C1im+:1-ethyl-3-methylimidazolium and FSA−:bis(fluorosulfonyl)amide) ionic liquid electrolytes for sodium secondary batteries. Journal of Power Sources
2014,
265, 36-39.
Investigation on Improved Electrochemical Performance of Layered Sodium Manganese Oxide By Partial Transformation of P2-Phase to O3-Phase for Sodium Ion Battery
Authors: Yang Junghoon , Kang Yong-Mook 
Published: February 2020

Layered structure sodium manganese oxides are the most popular cathode materials for sodium ion battery due to their superior electrochemical performances with low cost. There are various structures of sodium manganese oxides based on the transition metal stacking arrangement and the coordination of Na ions in the structure. Among various structures of the layered structure materials, sodium manganese oxide has two representative structures which are P2- and O3- phases. The letter denoted as P and O indicates the trigonal prismatic and octahedral coordination of Na ions in the structure, respectively. And the number of transition metal layer in unit cells is written after the letter. Therefore, P2- and O-3 type phases have trigonal prismatic and octahedral sites for Na ions occupying, and two and three different MnO2 layers per unit cell, respectively. Generally, P2- and O3-type materials exhibit different intrinsic electrochemical behaviour due to their different Na ion occupation sites and Na ion concentrations. The P2-type materials show low initial charge capacity due to large unoccupied Na ion site and low reversible capacity. The low initial charge capacity cause severe problem when it is adopted as a cathode for full-cell system. O3-type materials provide higher initial capacity and reversible capacity than P2-type materials. However, O3-type materials exhibit lower Na ions diffusivity because Na ions should diffuse through face-shared interstitial tetrahedral sites in the structure. Furthermore, they show fast degradation when it is charged above 4.0V due to structural instability.
In this study, we provide the enhanced electrochemical performances of sodium manganese oxide by partial transformation from P2-type to O3-type phase. The P2- and O3- mixed phase suggest the novel ways to overcome the disadvantages of each phase, by adopting the advantages of opponent phase. The mixed phase for layered structure cathode materials present the new ways for the development of cathode materials with improved properties.
Development of a Low Power Ammonia Gas Sensor
Authors: Navaei Milad , Hesketh Peter 
Published: February 2020

In recent years, there has been significant growth in gas sensor industries given their ability in detecting explosives, pollution, and toxic gases. In fact, one of the most highly toxic gases is Ammonia, which is widely produced in industries such as chemical, fertilizer, and food processing. In chicken farms, the Ammonia produced from the excretes of the chickens show decrease in the quality and quantity of egg and meat production, and may inhibit growth in cell lines.
A miniature, low-power, thermal conductivity sensor has been developed. The sensor was batch fabricated and is CMOS-compatible. Joule heating is the main driving principle behind Thermal conductivity sensors where the Polysilicon micro-bridge is heated by applying a fixed current while measuring the resistance change of the bridge as it interacts with the surrounding gas.To better understand the sensor performance and sensitivity, the sensor was simulated in COMSOL Multiphysics by coupling the electrical and thermal physics. The model results show the temperature distribution of the heated mico-bridge. Furthermore, steady state response as well as transient response of the sensor were studied. The transient response provides more information about the physical properties of the gases such as thermal conductivity and thermal capacity. The COMSOL simulation revealed that having a wider anchors and suspending the bridge from the substrate will improve the temperature uniformity, which ultimately improve the detector performance and reduce the heat loss through the substrate.
Furthermore, an electrical circuit was developed to measure the resistance change of the sensor with high accuracy while reducing the signal to noise ratio. Teensy 3.2 was used to excite the sensor at a fixed frequency and measure the change in resistance. The resistance value of the sensor was then transmitted to a cell phone to be analyzed. There are three resistance components in this circuit which are the sensor (RSensor), reference sensor (RR), corresponding resistance (R), and an op-amp (OPA1324). In order to measure the change in resistance of the TCD, the value of RR and R were fixed (RR =3010 Ω and R=332 Ω), and the output voltage of the op-amp was measured using .The sensor was first tested in air, helium and 0.01% ammonia. The sensor shows good sensitivity to low ppm levels of Ammonia at the room temperature. The sensor performance measurements in less than 0.2 ms while consuming 5 nJ per reading.
Amperometric Gas Sensors: From Classical Industrial Health and Safety to Environmental Awareness and Public Health
Authors: Carter Michael T , Stetter Joseph R , Findlay Melvin W , Meulendyk Bennett J. , Patel Vinay , Peaslee David 
Published: February 2020

KWJ Engineering and SPEC Sensors LLC have been working to develop and commercialize a new class of amperometric gas sensor, the screen-printed electrochemical sensor (SPEC) for the past several years. These new, tiny, ultralow power sensors and device built around them are making in-roads in a diverse set of endeavors. Much of this potential has been driven by the explosion of interest and activity in sensor technologies driven by our increasingly connected world (Internet of Things). Amperometric gas sensors were once found mainly in industrial hygiene applications, e.g., four gas monitors, confined space entry monitoring and leak detection. Conventional sensors are fairly large, although not requiring particularly high power (on the order of tens of milliwatts). However, they are not compatible with modern needs. The advent of tiny form factors with the SPEC sensor has opened up new possibilities in applications requiring portability, wearability (e.g., watches or other personal monitoring devices) and self-powered or long-term unattended battery operation by virtue of the very small size and ultralow power (microwatt) requirements.
This paper will review several recent efforts in next-generation gas sensor development and applications at KWJ Engineering. Major scientific directions include portable and wearable environmental monitoring of inhalation hazards for personal and public health protection and detection and classification of odors.
Anion Conducting Multiblock Copolymers
Authors: Liu Lisha , Ahlfield John M. , Kohl Paul A 
Published: February 2020

Anion Exchange Membrane (AEM) fuel cells are a possible route to overcoming fundamental issues with acid-based fuel cells. The issues include the high cost of platinum catalysts, complex water management, and sluggish electrochemical reactions. However, the performance of AEM fuel cells is not as good as that of Proton Exchange Membrane (PEM) fuel cells partially because of the limitations of current anion exchange membranes, such as low ionic conductivity, poor stability at high pH, and high water uptake.
A series of partially fluorinated multiblock copoly(arylene ether)s with long head-group tether were synthesized for use in AEM fuel cells and electrolyzers. The multiblock copolymers were synthesized via polycondensation of hydroxyl-terminated oligomers and fluoro-terminated oligomers. The resulting multiblock structure has one hydrophilic block and one hydrophobic block. It was designed so that nanophase-separation occurs and efficient conductive channels are formed with low water uptake. Multiblock copolymers with different block lengths and ion exchange capacity (IEC) were synthesized to maximize ion conductivity and explore the relationship between chemical structures and membrane properties. A non-linear relationship was found between the number of head-groups on a hydrophilic block and the conductivity. Doubling the number of head-groups more than doubled the hydroxide conductivity. Hydroxide conductivity as high as 119 mS/cm at 80°C have been observed with a specific size block size: X5.4Y7, where X is the hydrophobic block and Y is the hydrophilic block. The hydrophobicity of the backbone has allowed synthesis of polymers with minimal water uptake. The ratio of conductivity-to-water uptake shows that less water is absorbed compared to conventional materials. The number of waters per ion within the polymer is as low as 4. This is reflected in the measurement of the amount of free-water and bound-water. No conductivity loss was observed after soaking the membrane in 1M NaOH solution at 60°C for over 700 hours.
Financial support from US Office of the Deputy Assistant Secretary of the Army for Defense Exports and Cooperation (DASA-DE&C) is gratefully acknowledged.