bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Battery Degradations Induced By Different Synthetic Driving Cycles and Real-World Traffic Conditions
Authors: Baure George , Dubarry Matthieu
Published: February 2020

Advances in lithium ion battery pack technology have led to significant market penetration for electric vehicles (EVs), but there is still a need to develop new battery technologies, better control algorithms, and faster charging strategies to enhance further the ownership experience. Once developed, these advances must be validated. Unfortunately, fleet testing is not often an option because of the associated cost.

To address this issue and permit the validation of new technologies in the laboratory quickly, many studies are relying on synthetic driving cycles to mimic the usage cells would experience under actual utilization. Among the more popular ones are the Federal Urban Driving Schedule (FUDS), a US standard; the Dynamic Stress Test (DST) which is a simplified version of the FUDS cycle; and the New European Driving Cycle (NEDC), a European standard. The ability of these cycles to replicate EV usage is usually taken for granted; whereas, to the best of our knowledge, no study has scrutinized these cycles to establish if the induced degradation is indeed comparable with what is observed from real driving data.

It is proposed here to investigate the impact of the most-used, standardized driving cycles on state-of-the art lithium-ion cells and evaluate them against the impact of real driving in a laboratory-controlled environment. Different analysis techniques and metrics, such as voltage response, capacity, rate capability, and resistance, are employed to compare the most common synthetic driving cycles (FUDS, DST and NEDC) with scaled-down real driving data selected from the Hawai'i Natural Energy Institute (HNEI) in-house database. Two different sets of real driving data was used, one using a single commute in a loop and one using 25 similar commutes in a loop, to reveal any effect of traffic.

This study aimed to elucidate any significant discrepancies between simulated and real driving outcomes, determine the effect of traffic conditions, and propose possible improvements.
Controlled Synthesis of Mos­2 Microparticles for Lithium Ion Batteries
Authors: Schuppert Nicholas David , Bates Alex , Lee Sang C. , Park Sam
Published: February 2020

Introduction – MoS2 is promising as alternative to traditional graphite anodes. MoS2 possesses a low redox potential relative to lithium and approximately 3x the theoretical capacity of graphite, making it an ideal candidate for lithium ion battery anodes [1, 2]. To achieve high storage capacities and stable capacities over many charge/discharge cycles, high electrochemically active surface areas and access to layer edge intercalation sites is required. Controlled growth of MoS2 microspheres, whose robust morphology should provide a stable structure and abundant access to intercalation sites also allows for the control of particle surface area to volume ratios, a key component to determining electrochemical activity of the anode particles. In this work, experimental parameters such as precursor materials, temperature and pressure are varied for the hydrothermal synthesis of MoS2 microparticles, giving control over particle morphology and size. The influence of surface area to volume ratios are then examined with respect to material stability and capacity. Fabrication procedures and preliminary results are shown in the following sections.

Fabrication procedures – Synthesis of MoS2 microspheres is accomplished by a hydrothermal procedure under high pressure. In a typical procedure hexammonium heptamolybdate tetrahydrate and thiourea are vigorously in a solution of deionized water. The solution is then transferred to a Teflon lined autoclave reactor vessel and heated to 220 °C for an extended period of time. The resulting black MoS2 precipitate is collected by centrifugation and washed with ethanol and deionized water several times to remove impurities. Lingering solvent is then removed by drying the material at low temperatures in atmosphere overnight.

Preliminary results – X-ray diffraction spectra of MoS2 microspheres taken at different reaction times are shown in Figure 1(a). Material crystallinity is observed to be dependent on reaction time. An SEM image typical of the fabricated MoS2 microspheres is shown in Figure 1(b), showing that the microspheres are composed of conglomerations of MoS2 sheets. Figure 1(c) shows particle size distributions of the three reaction times. All resulted in two size distributions per reaction time, with an increase in reaction time yielding an increase in both particle size distributions. Figure 1(d) shows surface area to volume ratios (S.V.R.) of the measured particle size distributions plotted against the S.V.R. function for a sphere.

References –

[1] T. Stephenson, Z. Li, B. Olsen, D. Mitlin, Energy & Environmental Science, 7 (2014) 209-231.

[2] N. Yabuuchi, K. Kubota, Y. Aoki, S. Komaba, The Journal of Physical Chemistry C, 120.

Figure 1
(Invited) Strategies for Tuning the Electrical Conductivity in Metal Organic Frameworks
Authors: Talin Albert Alec
Published: February 2020

Interest in electrically conducting metal organic frameworks is rapidly growing, motivated by the prospect of combining within a single material the highly ordered structure of inorganic materials with the tunable properties and low cost of organics. Furthermore, the structure-inherent nanoscale porosity of MOFs provides an ideal route to tuning the electronic properties of these materials with guest molecules without necessarily increasing structural disorder. These unique qualities make electrically conducting MOFs attractive for variety of applications in electronics, opto-electronics, sensing and energy storage/energy conversion applications. These qualities, however, also present significant challenges in interpretation and reproducibility of charge transport in MOFs. In my presentation I will discuss the strategies for achieving and controlling electrical conductivity in MOFs using examples from our group’s work on Guest@MOF conductors as well as recent results from the literature. In addition, I will discuss recent thermoelectric measurements which suggest that conducting MOFs may be useful in waste heat recovery applications.
(Invited) Safe, High-Energy-Density, Solid-State Li Batteries
Authors: Wachsman Eric D.
Published: February 2020

We have developed transformational, and intrinsically safe, all-solid-state Li-ion batteries (SSLiBs), by incorporating high conductivity garnet-type solid Li-ion electrolytes into tailored tri-layer microstructures, by low-cost solid oxide fuel cell (SOFC) fabrication techniques to form electrode supported dense thin-film (~10μm) solid-state electrolytes. The microstrucurally tailored porous garnet scaffold support increases electrode/electrolyte interfacial area, overcoming the high impedance typical of planar geometry SSLiBs resulting in an area specific resistance (ASR) of only ~2 to 7 Ωcm-2 at room temperature. The unique garnet scaffold/electrolyte/scaffold structure further allows for charge/discharge of the Li-metal anode and cathode scaffolds by pore-filling, thus providing high depth of discharge ability without mechanical cycling fatigue seen with typical electrodes. Moreover, these scalable multilayer ceramic fabrication techniques, without need for dry rooms or vacuum equipment, provide for dramatically reduced manufacturing cost.

Fabrication of supported dense thin-film garnet electrolytes, their ability to cycle Li-metal at high current densities with no dendrite formation, and results for Li-metal anode/garnet-electrolyte based batteries with a number of different cathode chemistries will be presented.
Zero Degradation in Power Density over Long-Term SOFC Operation Based on a Novel Interlayer
Authors: Wang Yudong , Dogdibegovic Emir , Zhou Xiao-Dong
Published: February 2020

Doped ceria interlayer is ubiquitously used between the cathode and electrolyte in solid oxide fuel cells to prevent the cathode/electrolyte interaction and offer a better thermal expansion match. The mechanism on how the interlayer influences the durability and activity of the cathode still remains elusive. This is particularly true in the nickelate cathode (e.g. Pr2NiO4) since the nickelate does go through a phase transition during operation. Traditional Gd-doped ceria was found to substantially accelerate the phase transition in Pr2NiO4 cathode, leading to faster cell degradation in performance. In this work, several new designs of the interlayer are adopted, including various approaches to add Pr into ceria. The addition of Pr in the ceria layer can suppress the phase decomposition of nickelate cathode and increase the performance. As a result, the cell performance exhibits zero degradation over 500 hours. Electrochemical impedance spectroscopy data and its distribution of relation times were obtained to understand the mechanism for this unique observation.

Key words: Doped ceria, interlayer, zero degradation, nickelate
Plating and Stripping Calcium at Room Temperature
Authors: Gao Xiangwen , Wang Da , Bruce Peter G.
Published: February 2020

Multivalent-ion batteries are receiving significant attention as potential post-lithium ion energy storage devices, such as Mg, Ca, etc.1-6 Among them, calcium has a potential much closer to Li (0.17 V vs. Li) and its natural abundance in the Earth’s crust make calcium cells potentially attractive. However, the major problem of calcium anodes is their tendency to reduce the organic electrolyte solvents forming passivating surface films such as CaO and CaCO3 that inhibit further plating.2,8-9 Recent studies showed calcium deposition under elevated temperatures, 75 to 100 °C, however with significant side reactions.5

Here, our recent studies show that calcium can be plated and stripped at room temperature with capacities of 1 mAh cm-2 at a rate of 1 mA cm-2, with low polarization (100 mV), in excess of 50 cycles and with low side reactions, Fig.1. The key role of the electrolyte, Ca(BH4)2 in tetrahydrofuran (THF), will be discussed.

Figure 1. Galvanostatic Ca plating/stripping load curves in Ca(BH4)2 in THF at the rate of 1 mA cm-2. Inset shows variation of coulombic efficiency with cycle number.

References:

Aurbach D., Lu Z., Schechter A., Gofer Y., Gizbar H., Turgeman R., et al. Prototype systems for rechargeable magnesium batteries. Nature, 407, 724-727 (2000).

Aurbach D., Skaletsky R., Gofer Y. The Electrochemical-Behavior of Calcium Electrodes in a Few Organic Electrolytes. J Electrochem Soc, 138, 3536-3545 (1991).

Lin M. C., Gong M., Lu B. G., Wu Y. P., Wang D. Y., Guan M. Y., et al. An ultrafast rechargeable aluminium-ion battery. Nature, 520, 324-328 (2015).

Muldoon J., Bucur C. B., Gregory T. Quest for Nonaqueous Multivalent Secondary Batteries: Magnesium and Beyond. Chem Rev, 114, 11683-11720 (2014).

Ponrouch A., Frontera C., Barde F., Palacin M. R. Towards a calcium-based rechargeable battery. Nat Mater, 15, 169-172 (2016).

Yoo H. D., Shterenberg I., Gofer Y., Gershinsky G., Pour N., Aurbach D. Mg rechargeable batteries: an on-going challenge. Energ Environ Sci, 6, 2265-2279 (2013).

Muldoon J., Bucur C. B., Oliver A. G., Sugimoto T., Matsui M., Kim H. S., et al. Electrolyte roadblocks to a magnesium rechargeable battery. Energ Environ Sci, 5, 5941-5950 (2012).

Hayashi M., Arai H., Ohtsuka H., Sakurai Y. Electrochemical characteristics of calcium in organic electrolyte solutions and vanadium oxides as calcium hosts. J Power Sources, 119, 617-620 (2003).

Canepa P., Gautam G. S., Hannah D. C., Malik R., Liu M., Gallagher K. G., et al. Odyssey of Multivalent Cathode Materials: Open Questions and Future Challenges. Chem Rev, 117, 4287-4341 (2017).

Figure 1
Screen-Printed Electrodes As EC-SERS Active Surfaces for Quantitative Raman Spectroelectrochemical Detection of Biologically-Related Species
Authors: Fanjul Bolado Pablo , Junquera Pérez Alejandro , González García María Begoña , Hernández Santos David
Published: February 2020

Surface-Enhanced Raman Scattering (SERS) is a very interesting technique for the detection of analytes at ultra-low concentrations. In recent years, it has been applied to the detection of species with biological or medical interest [1]. However, one of the key issues of SERS-based assays is the low reproducibility between different substrates and measurements due to the low control of hot spots and the strong influence of the surface features on the SERS activity. Therefore, there is a strong scientific interest for increasing the applicability of SERS assays for quantitative studies with reproducible and simple methods. Electrochemically roughened electrodes have been widely employed for SERS-based assays. Recently, we have demonstrated that the utilization of screen-printed electrodes with in situ dynamic simultaneous roughening and detection could improve the precision of these assays [2]. Furthermore, the dynamic and in situ electrogeneration of SERS substrates allows to obtain a strongly active metallic surface for increasing detection sensitivity. Screen-printed electrodes due to their versatility, precise mass-fabrication, disposability and low-cost could be promising SERS substrates.

In this work, the evaluation of electrochemical SERS (EC-SERS) for the detection of biologically-related species at very low concentrations is performed using metallic screen-printed electrodes. Several species with a possible biological interest were tested such as Ruthenium-bipyridine, Naratriptan or Nicotinamide. Ruthenium-bipyridine is a very interesting molecule because it is the most common detection label in electrochemiluminescence bioassays due to its exceptional performance and sensitivity. Naratriptan is a pharmaceutical active ingredient used for the treatment of migraine headaches in human beings. Nicotinamide is an essential B-vitamin necessary to support the function of many biological enzymes. EC-SERS using screen-printed electrodes allows the detection of these species at very low concentrations.

[1] L.A. Lane, X. Qian, S. Nie, “SERS Nanoparticles in Medicine: From Label-Free Detection to Spectroscopic Tagging”, Chem. Rev. 115 (2015), 10489-10529.

[2] D. Martín-Yerga, A. Pérez-Junquera, M.B. González-García, J.V. Perales, A. Heras, A. Colina, D. Hernández-Santos, P. Fanjul-Bolado, “Quantitative Raman Spectroelectrochemistry using silver screen-printed electrodes”, Electrochim. Acta 264 (2018), 183-190.
Oxidation of Antioxidant Species with Superoxide Radicals Produced By the Xanthine-Xanthine Oxidase System
Authors: Juarez-Gomez Jorge , Ramírez-Silva María Teresa , Palomar Manuel , Romero-Romo Mario
Published: February 2020

Free radicals have become very important in recent years due to the damage they cause to biological molecules. The superoxide radical (O2•-) is the primary species of reactive oxygen species (ROS) that plays a major role in physiological processes. This radical normally is produced physiologically at such a rate that the human body is able to catabolize it. However, when the production of O2•- radicals exceeds the capacity of the human body, physiological imbalances become harmful.

In this work the xanthine oxidase enzyme is proposed to catalyze the oxidation of xanthine and take advantage of the production of O2•- radicals. The O2•- formed in the enzymatic reaction are reacted with different antioxidant compounds (caffeic acid, gallic acid, ascorbic acid) and the oxidized species are quantified by cyclic voltammetry in an electrochemical cell thermostatted at 30 °C in a medium buffered with phosphate buffer 0.1 mol L−
1 pH 7.0. A carbon paste electrode was the working electrode, Ag/AgCl the reference and platinum the counter electrode. All antioxidants have an oxidation process between 200 and 600 mV, as well as a reduction process between −200 and 200 mV. The enzyme and the substrate do not present redox processes in the work potentials. However, uric acid has an oxidation process around 400 mV, but does not present reduction processes.
New Reference Electrodes for Air and Moisture Stable Ionic Liquids
Authors: Horwood Corie , Stadermann Michael
Published: February 2020

The use of room temperature ionic liquids (RTILs) for electrochemical applications such as fuel cells, batteries, dye-sensitized solar cells, and supercapacitors, has gained significant interest over the last decade. Despite the increase in attention, a universal reference electrode for use in RTIL electrochemistry has not been adopted. A stable, easy to prepare, and reproducible reference electrode, analogous to Ag/AgCl reference electrodes for aqueous electrochemistry, is crucial for accurately determining redox potentials as well as for comparing these potentials between RTILs and between research labs.

Electrochemical work in RTILs often rely on quasi-reference electrodes (QREs),1 such as Ag or Pt wire, which must be calibrated by the addition of a redox couple (e.g. ferrocene/ferrocenium) after each electrochemical measurement. These quasi-reference electrodes are difficult to reproduce, likely due to the quality of the wire used and the presence of surface adsorbates. Furthermore, they have been known to exhibit potential drift during use, with 10s to 100s of mV drift often observed. Ferrocene is added after the experiment, however this one-point calibration of the QRE does not necessarily apply throughout the entire experiment, as the QRE may drift during the measurement.2

We report on reference electrodes designed for use in ionic liquids, which exhibit stable potential over several months of experimental use. One successful example is based on a silver wire coated with silver sulfide.3 The reference electrode potential is determined by the concentrations of Ag+ and S2
−, which are established by the solubility of the Ag2S coating on the Ag wire. Our reference electrode can be prepared and used in a normal air atmosphere, and does not need to be assembled and used in a glovebox, or protected from light. The reference electrode has been characterized by voltammetry measurements of ferrocene and cobaltocenium hexafluorophosphate, and was found to slowly drift to more positive potentials at a rate of <1 mV/day for five RTILs investigated over the course of 2+ months.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM release LLNL-ABS-748348.

(1) Electrochemical aspects of ionic liquids, 2nd ed.; Ohno, H., Ed.; John Wiley & Sons Inc., 2011.

(2) Torriero, A. A. J.; Sunarso, J.; Howlett, P. C. Electrochim. Acta
2012, 82, 60–68.

(3) Horwood, C.; Stadermann, M. Electrochem. Commun.
2018, 88 (December 2017), 105–108.
Development of an Inert Anode for the Electrolytic Reduction of Cerium Oxide
Authors: Rodriguez David , Monreal Marisa , Jackson Matt , Weisbrod Kirk
Published: February 2020

Since the early 2000s, when the Fray-Farthing-Chen (FFC, direct mechanism) and the Ono-Suzuki (OS, indirect mechanism) processes for the reduction of titanium oxide were elucidated, several additional metal oxides (ZrO2, Ta2O5, Cr2O3, and Nb2O5) have been reported to electrolytically reduce to their metallic state in molten CaCl2-CaO.1-3 In our hands, the electrolytic reduction of cerium oxide has resulted in mixed degrees of success due to side reactions within the molten salt. Cyclic voltammetry (CV) was performed in order to identify the products of these side reactions, and resulted in greater understanding of the system; based on CV results, parameters were refined, resulting in an improved production of Ce0. When Ce0 was successfully produced by electrolytic oxide reduction, a large amount of passed charge was required due to various inefficiencies of the process, requiring further optimization. Anode material has been identified as a possible source of inefficiency, as it degrades throughout an experiment. Currently, pyrolytic graphite is used as the anode, which leads to carbon dissolution and contamination of the salt bath. As such, the goal of this study is to identify an inert anode material and operational parameters to ensure greater yields of metallic product.

References

Chen, G. Z., Fray, D. J. & Farthing, T. W. Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride. Nature
407, 361-364 (2000).

Claux, B., Serp, J. & Fouletier, J. Electrochemical reduction of cerium oxide into metal. Electrochimica Acta
56, 2771-2780, (2011).

Suzuki, R. O., Ono, K. & Teranuma, K. Calciothermic reduction of titanium oxide and insitu electrolysis in molten CaCl2. Metallurgical and Materials Transactions B
34, 287-295, (2003).

LA-UR-18-22498
H/D Isotope Effects on Nuclear Shielding As a Tool for the Study of Interionic Hydrogen Bonds in Ionic Liquids
Authors: Bottini Gualberto , Pérez Cecilia , Moyna Guillermo
Published: February 2020

H/D isotope effects on nuclear shielding (IENS) have found applications in the study of reaction kinetics, chemical and conformational equilibria, and non-bonded interactions. In particular, they are especially well-suited to investigate hydrogen bonded (H-bonded) systems. In this presentation, we demonstrate that H/D IENS are indeed a powerful tool to scrutinize interionic H-bonds in ionic liquids (ILs), using 1-n-alkyl-3-methylimidazolium salts as examples. Results obtained with protonated and deuterated isotopologues of 1-n-butyl-3-methylimidazolium chloride ([C4mim]Cl), tetrafluroborate ([C4mim]BF4), and hexafluorofosphate ([C4mim]PF6) indicate that IENS on the 35/37Cl and 19F resonances of the anions, or D35/37Cl(H,D) and D19F(H,D), allow to identify and differentiate H-bonds between the anion and the different aromatic protons on the cation. Furthermore, IENS measured on sequentially deuterated [C4mim]BF4 and [C4mim]PF6 isotopologues reveal the formation of aliphatic C-H⋅⋅⋅X hydrogen bonds between the fluorinated anions and hydrogens along the N-alkyl sidechains of the cations. Our findings also indicate that the interactions between the fluorinated anions and hydrogens on the C-1’ and C-1” position of the N-alkyl sidechains are comparable to, and in some cases stronger than, those involving protons on the aromatic ring, underscoring the role that these weak interionic forces have on the local ordering of imidazolium salts in the liquid state. The methodology also shows that the length of the N-alkyl sidechain anchored on the N-1 position has no sizable effect on the strength of interionic H-bonds in this type of ILs. Current studies involving variations on the sidechain structure, was well as applications of the approach to the study of other systems bearing NMR-active nuclei, are discussed.

Figure 1
Evaluating the Effect of Applied Tension during Natural Fiber Welding of Lignocellulose Yarns
Authors: Burn Adam , Durkin David P. , Fahey Patrick J. , De Long Hugh C. , Trulove Paul C.
Published: February 2020

This study evaluated how applying tension in the axial dimension during Natural Fiber Welding (NFW) of lignocellulose yarn impacted the fibers mechanical and morphological properties. Understanding the combined effects of applied tension and polymer mobilization is vital both for controlling sample contraction during NFW experiments, and will inform the design of scale-up processes that rely upon tension for pulling yarn and cloth stocks through continuous treatment. The tensile strength and Young’s modulus of the fiber-welded taut linen yarns slightly increased over the tension values for the untreated linen. The greatest increase in the tensile strength and Young’s modulus of the treated linen yarn occurred when taut linen yarn was treated with either 1-ethyl-3-methylimidazolium acetate or acetonitrile at 40 °C for 60 s. No tensile value improvements were observed in the NFW treated taut bamboo yarns. However, slight increases in the energy at break and tensile strength were observed when bamboo yarn was treated with methanol or warm acetonitrile. It is thought that the observed tension property differences between the treated linen and bamboo yarns is related to the cellulose and lignin content in the tested material.
Kinetics of the Reduction of Rare Earth Metals in LiCl–KCl–Cscl Eutectic Melt
Authors: Shchetinskiy Andrey V. , Kharina Ekaterina A. , Volkovich Vladimir A. , Dedyukhin Alexander S.
Published: February 2020

Modeling and developing high temperature processes involving rare earth metals relies on comprehensive data concerning their behavior in molten salt media. The aim of the present study was determining kinetic parameters of reduction of lanthanum, praseodymium and neodymium ions in the melts based on the ternary eutectic mixture of lithium, potassium and cesium chlorides. The experiments were performed at 400–750 oC on a tungsten working electrode employing cyclic voltammetry and chronopotentiometry. Potentials were measured vs. chlorine reference electrode.

Reduction of Ln(III) ions to Ln(0) for all the elements studied occurred as a single stage process. The process is reversible and controlled by diffusion. Transition time of the process was determined and diffusion coefficients of Ln3+ ions calculated.
Ionic Liquid Meidated Synthesis of Cellulose and Chitosan Composite for Purification of Drinking Water
Authors: Tran Chieu D. , Nyakuchena James
Published: February 2020

A simple method was developed to synthesize composites containing cellulose (CEL) chitosan (CS), keratin (KER) (from wool, hair and chicken feather) and metal nanoparticles including silver, gold and copper oxide nanoparticles (AgNPs, AuNPs and CuONPs). In this method, butylmethylimmidazolium chloride ([BMIm+Cl-]), a simple ionic liquid, was used as the sole solvent and metal salts such as silver chloride, HAuCl4 or Copper oxide was added to the [BMIm+Cl-] solution during the dissolution process. The metal salts in the composites were completely converted to metallic nanoparticles (Ag0NPs, Au0NPS or CuONPs) by reducing it with NaBH4. FTIR, XRD and SEM results confirm that CEL, CS and KER remain chemically intact and homogeneously distributed in the composites, and that the Ag0NPs, Au0NPs or CuONPs in the composites is homogeneously distributed throughout the composites. All composites were found to exhibit excellent adsorbent for pollutants (endocrine disruptors, heavy metal ions) and antibacterial activity against many bacteria and fungi including Escherichia coli, Staphylococus aureus, Pseudomonas aeruginosa, methicillin resistant Staphylococus
aureus (MRSA), vancomycin resistant Enterococus faecalis (VRE) and Candida Albicans. The antibacterial activity of both composites increases with the content of the nanoparticles in the composites. All nanoparticles composites were found to be toxic to human fibroblasts at higher concentration (e.g., >0.72 mmol for Ag0NPs). As expected, by lowering concentration of the NPs, (e.g., Ag0NPs concentration to <0.48 mmol), all three nanoparticle composites can be made biocompatible while still retaining their pollutant adsorber and antimicrobial activity. These results together with our previous finding that [CEL+CS+KER] composites can be used for controlled delivery of drugs (e.g. Ciprofloxacin) clearly indicate that the silver, gold and copper oxide nanoparticle composites possess all required properties for successfully used as dressing to treat chronic ulcerous infected wounds and to purify drinking water.
(Invited) Cellulose and Ionic Liquids Beyond Dissolution
Authors: Byrne Nolene
Published: February 2020

Cellulose finds use in a wide variety of applications and owing to its renewable abundant nature the use of cellulose in new applications is increasing. The ability of ionic liquids to dissolve cellulose was a catalyst for significant ionic liquid development and research in the early 2000’s to present day. Many applications and research papers exist on the topic of ionic liquids and cellulose from understanding dissolution mechanisms to developing functionalized forms of cellulose. In this talk, our efforts on processing cellulose and other lignocellulose types with ionic liquids will be discussed covering topics from spinning regenerated cellulose fibres to the development of cellulose aerogels with tunable pore structures, including recycling textiles materials using ionic liquid solvents. The influence of dissolution and regeneration is a common theme for each of these processes and impacts the properties of the final material. Application properties will also discussed.

Figure 1:

Aerogels produced using different ionic liquids resulting in different pore morphology and mechanical properties.

Figure 2:

Regenerated lignocellulose fibres produced under different draw and different solvents: below carbon fibre from regenerated lignocellulose precursor

Figure 1
New Co-Electrolysis Cell Design with Improved CO2 Reduction Efficiency
Authors: Patru Alexandra , Pribyl Bernhard , Schmidt Thomas J.
Published: February 2020

Electrochemical CO2 reduction it is an attractive method for minimizing the level of atmospheric CO2 and storing energy 1
,
2. When this process is coupled to a renewable energy source such as wind or solar, carbon dioxide is converted to fuels or chemical feedstock. To reduce important quantities of CO2, specific devices named co-electrolyser are needed. For high efficiency of these devices several parameters need to be integrated: i) active cathode catalyst for CO2 reduction reaction (CO2RR), ii) optimal cathode pH, iii) adequate polymer electrolytes when the CO2RR takes place from gas phase and iv) rational engineering for low energy consumption.

Our work presents the design of a new co-electrolysis cell operating at low temperature (i.e. 40°C) where not liquid electrolyte is used for CO2RR. This new cell configuration made use of a standard Nafion® cation exchange membrane in combination with a modified cathode catalyst layer preparation: an alkaline anion exchange ionomer was used within the cathode catalyst layer, and an additional thin film of the same alkaline ionomer was coated on the cathode catalyst layer in order to prevent direct contact between the cathode catalyst and the acidic cation exchange membrane. Different types of silver catalysts are investigated under this configuration 3. The cells faradaic and energetic efficiencies are compared with those obtained for the same catalysts in standard three electrode cells using liquid electrolytes4.

References

J. Durst et al., Chimia, 69, 769–776 (2015).

J. Herranz et al., Nano Energy, 29 (2016).

A. Dutta, M. Rahaman, N. C. Luedi, M. Mohos, and P. Broekmann, ACS Catal., 6, 3804–3814 (2016).

K. P. Kuhl, E. Cave, D. N. Abram, and T. F. Jaramillo, Energy Environ. Sci., 5, 7050–7059 (2012).

Acknowledgements

Financial support of this work by the Swiss Innovation Agency (Innosuisse) and the Swiss Competence Center for Energy Research Heat and Electricity Storage are greatly acknowledged.
Enhanced Hydrogen Evolution Activity on the Edge of MoS2 through W Substitution
Authors: Wang Hao , Gao Lijun
Published: February 2020

Hydrogen evolution reaction (HER) activities could be enhanced on MoS2 through exotic doping by introducing active centers. In this work, we explored HER activity on MoS2 edge by alloying isovalent W into MoS2 nanosheets. The first-principles calculations predicted that optimum HER performance may be achieved with W substituting 50% of Mo in MoS2 due to the decrease of H adsorption free energy ΔGH and facilitation of charge transfer at the electrode interface. At a H coverage of 25% on Mo0.5W0.5S2, the value of ΔGH reaches minimum which favors both H adsorption and desorption processes on catalyst surface, and electronic conductivity of the material is also enhanced through PDOS calculation. Experiments demonstrated that Mo0.5W0.5S2 significantly enhanced HER performance with a low onset potential of -37 mV, a Tafel slope of 55 mV dec-1, and an overpotential of 138 mV at 10 mA cm-2, which is among the best performance of reported MoS2 based compounds. The Mo0.5W0.5S2 also showed excellent stability during polarization.

Figure 1
(Invited) In Situ/Operando Investigations of Energy Materials with Soft and Hard X-Ray Spectroscopy
Authors: Dong Chung-Li
Published: February 2020

Energy issues have become globally important public concerns, and low-carbon green energy will play a key role in the near future. To decrease global greenhouse gas emissions in response to globalization and increasingly stringent carbon emission policies, it is necessary to establish green energy technologies. It has always been a great challenge to boost the energy conversion/generation/storage efficiency of current energy materials. Understanding and controlling the interfacial electronic properties in energy conversion/storage materials requires in-situ/operando characterization tools, of which synchrotron x-ray spectroscopy has many unique features. X-ray absorption spectroscopy is capable to probe the local unoccupied electronic structure (conduction band) while x-ray emission spectroscopy is able to probe the occupied electronic structure (valence band). The addition of resonant inelastic x-ray scattering determines the inter- or intra-electric transitions (d-d, f-f excitation or electron transfer excitation) that reflect the chemical and physical properties. With in situ/operando approach, the way to track the modification of atomic and electronic structures of the energy material under operational environment now becomes accessible. This presentation will report the current achievements and perspectives of in situ/operando synchrotron x-ray spectroscopy, including soft- and hard-x-ray absorption spectroscopy, on energy relevant materials.
(Invited) Oxide Nanowires Array Based CdSe/CdS/TiO2 1-D Heterojunction Photoelectrode for Enhanced Solar Fuel Conversion
Authors: Lee Jung-Kun , Han Gillsang , Caliskan Salim
Published: February 2020

Production of hydrogen by photoelectrochemical system has received considerable interest as one of the promising route without generation any undesired pollutants. A major component of a photoelectrochemical (PEC) water splitting system is the photoelectrode where critical processes such as light harvesting, generation of charge carriers, minority carrier migration towards its interface with the electrolyte, as well as majority carrier transportation towards the external circuit for water splitting. Co-sensitization by double-shell of QDs (e.g., CdSe/CdS) for the TiO2 or ZnO nanostructures demonstrated a large PEC performance improvement due to their extension of light absorption range. A sequential coating of two different light absorbers on the electrode (e.g. CdS/CdSe multilayer structure on TiO2) forms terraces in their band diagram (i.e, type II heterojunction), thus the aligned band edge promotes separation of electrons and holes and cascade-like carrier transport at their interface, and thereby increases the photocurrent The deposition of these QDs on one-dimensional (1-D) nanostructures of semiconductor including nanowires/nanorods (NWs/NRs) and nanotubes (NTs) increases the charge transport properties by providing a “highway” for electron travel. Although a few recent studies have shown that the ITO NWs improves the charge transport/collection for a single layer light absorber, their overall PEC performance is still lower than theoretically expected value because the photoelectrode absorb only a part of visible light (by a single layer absorber) and/or photo-generated charge carriers are largely recombined in the light absorber layer due to a low charge separation efficiency.

In the present study, we employed In2O3 and SnO2 NWs as a support for the CdSe/CdS/TiO2 multi-shelled heterojunction photoelectrode to demonstrate a largely enhanced PEC hydrogen production by improving the charge transport property. PEC performance of the resultant CdSe/CdS/TiO2/ITO NWs photoelectrode for the hydrogen production was investigated and they are compared with those of a planar structured and m-TiO2 nanoparticles based CdSe/CdS heterojunction photoelectrodes. The resultant 1-D heterojunction photoelectrode (CdSe/CdS/TiO2/ITO NWs) shows improved light absorption and charge transport properties in comparison to the planar structured photoelectrode (without the ITO NWs) and mesoporous TiO2 nanoparticles film based photoelectrode. We found that the ITO NWs based CdSe/CdS/TiO2 multi-shelled photoelectrode exhibits photocurrent density of ~16.2 mA/cm2, which is 2.4 times higher than that of m-TiO2 nanoparticles based photoelectrode and even outperforms previously reported TiO2 or ZnO NWs based photoelectrodes.
Effect of Nanochannels Prepared By Nano Polystyrene Beads in Photoelectrode on Photo Conversion Efficiency of Dye-Sensitized Solar Cells
Authors: Song Shin Ae , Kim Kiyoung , Lim Sung Nam
Published: February 2020

In dye-sensitized solar cell (DSSC) system, the real contact area between the dye and the electrolyte is very important because of fast readiness for separating electrons and holes by the light energy being original form of dye by redox reaction between dye and electrolyte. In order to enhance the photo-electric conversion efficiency in dye sensitive solar cells (DSSCs), the photoelectrode with nano-channels was prepared. The photoelectrode with nano-channel is able to enlarge active area for charge transfer among TiO2/dye/electrolyte. For preparing nano-channels in the photoelectrode, the polystyrene (PS) beads prepared by solution polymerization were added when preparing TiO2 pastes for photo-electrode film. Added nano PS beads in photoelectrode were decomposed and formed the nano-channels when heat-treating at 500 oC for sintering between TiO2 particles. The cell efficiencies of cells without and with nano-channels by PS beads (10%) are 5.19 and 7.47%, respectively. The cell photovoltaic performance is dramatically improved because of effective delivery of electron and hole to electrodes at the enlarged boundaries among dye/TiO2/electrolyte due to the increase of the impregnation amount of dye and electrolyte via the nano-channels formed by the decomposition of nano PS beads.
(Invited) Detection of Uranium Using Plasmonic and SERS Sensors
Authors: Haes Amanda J , Lu Grace , Phan Hoa
Published: February 2020

Uranium, a radioactive material with a long half-life, accumulates in the environment in its oxidative form uranyl, which can contaminate soil and water. Importantly, uranyl forms complexes with anions and cations thereby influencing solubility, toxicity, and fate of these heavy metal species. Furthermore, uranyl speciation varies with pH. The resulting complex speciation complicates detection and/or requires significant sample pretreatment. As such, methods that are capable of identifying trace uranyl species in complex samples are needed. Herein, localized surface plasmon resonance spectroscopy (LSPR), Raman spectroscopy, and surface enhanced Raman scattering (SERS) serve as label-free and near real-time methods for identifying uranium species in complex aqueous solutions. A straight-forward protocol for spectral analysis will be shown using Raman spectroscopy and aqueous uranium samples. Raman excitation wavelength, pH, and coordinating ions are systematically varied. The spectral analysis results are rigorously validated using uranyl speciation models. Next, plasmonic nanomaterials are used to enhance the Raman signals for trace detection of low (and high) abundant species. Finally, an approach that promotes the reproducible detection of uranyl using SERS will be shown. All in all, the developed protocol provides an accurate and routine analysis of Raman spectra for uranyl species identification and relative abundance elucidation. These advances are expected to provide a straight-forward approach for uranium species identified using LSPR spectroscopy, Raman spectroscopy, and SERS.
Amperometric Sensing of Bilirubin By the Ionic Liquid Doped Imprinted Polymer Modified Electrode
Authors: Syu Mei-Jywan , Tseng Yan-Di
Published: February 2020

Bilirubin is a metabolite of hemoglobin. Concentration of bilirubin in serum is often regarded as an important physiological indicator for judging the liver disease. In this work, molecularly imprinted polymer (MIP) doped with room-temperature ionic liquid (RTIL) and bilirubin template molecule was fabricated onto the surface of Au electrode. Both methacrylic acid (MAA) and ethylene glycol dimethyl acrylate (EGDMA) were used as the functional monomers. EGDMA was also used as the corsslinker. 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([BMIM][TF2N]) was the chosen RTIL. Together with bilirubin, the bilirubin-imprinted [BMIM][TF2N]-d-poly(MAA-EGDMA) ([BMIM][TF2N] doped poly(MAA-co-EGDMA)) was synthesized onto the Au surface. The SEM images showed that the polymeric film thus prepared was rather uniform and the average thickness was approximately 1.98 μm. After the extraction by a proper solvent, most bilirubin (the imprinted template molecule) was removed from the imprinted [BMIM][TF2N]-d-poly(MAA-EGDMA) film. Consequently, specific binding cavity for bilirubin was created after the extraction. Via which, electrochemical sensing of bilirubin by the amperometric mode owing to the specific interaction of the polymer film with bilirubin template would become feasible.

RTIL could enhance the amperometric signal of the MIP electrode. The imprinting factor of 5.52 ± 0.09 and the detection sensitivity of 0.367 ± 0.019 μA/cm2/mg/dL for bilirubin were achieved, respectively, from the imprinted [BMIM][TF2N]-d-poly(MAA-EGDMA) modified Au electrode. The RTIL doped MIP electrode is even able to detect bilirubin in the low concentration ranging from 0.2 to 1.0 mg/dL. The selectivity of bilirubin against biliverdin was 2.13. Additionally, the MIP electrode could discriminate bilirubin in the presence of serum. In summary, the experimental results confirm the feasibility of the RTIL-MIP electrode for the detection of bilirubin in serum.

Keywords: bilirubin, molecularly imprinted polymer (MIP), room-temperature ionic liquid (RTIL)

References

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Synthesis of Millimeter-Long Tungsten Oxide Nanowires for Flexible Molecule Sensor
Authors: Zhang Guozhu , Nagashima Kazuki , Mizukami Wataru , Kanai Masaki , Takahashi Tsunaki , Yanagida Takeshi
Published: February 2020

As one of the crucially important oxide 1D nanostructures, tungsten oxide (WO3) nanowire holds great promise for diverse applications range from the electrochromic to high performance of catalysis, sensors, photoelectric catalyst for water splitting, etc. However, although great efforts have been made to elongate the WO3 nanowire, the length of the as-grown nanowire is still limited at several tens of micrometers, which impedes its extensively applications in the flexible and wearable electronics. Here, we firstly realize the millimeter-level WO3 nanowire growth and demonstrate the feasibility of such ultra-long WO3 nanowire integrated with the flexible substrate for the molecule sensing application. It is found that the ultra-long WO3 nanowire constructed flexible sensor presents a superior sensing performance and mechanical robustness to the lung cancer biomarker molecules. The detail synthesis method, nanowire growth mechanism and performance of the flexible WO3 nanowire sensor will be presented at the meeting.
Preparation of Photoluminescent Molybdenum Disulfide Quantum Dots for Biomedical Imaging
Authors: Liu Li , Meng He , Dong Jian , Zhao Yanli , Dong Lifeng
Published: February 2020

Since the discovery of graphene, great attention has been paid to transition metal disulfide two-dimensional layered materials due to their exceptional physical and chemical properties. Recently, molybdenum disulfide (MoS2) quantum dots (QDs) have been extensively investigated because of their unique quantum confinement and boundary effects as well as potential applications in fluorescence imaging, electrochemical catalysis, and biosensors. The preparation of MoS2 quantum dots can be divided into two types: bottom-up method and top-down method. In order to prepare aqueous MoS2 QDs solution, in this study, we develop a bottom-up strategy to synthesize MoS2 QDs using a simple, one-step hydrothermal method with ammonium tetrathiomolybdate [(NH4)2MoS4] as the precursor and hydrazine hydrate as the reducing agent. The morphology and structural characteristics of MoS2 QDs are analyzed by transmission electron microscopy, and optical properties are characterized using UV-Vis and photoluminescence spectroscopy. Also, the cytotoxicity of MoS2 QDs are tested. Experimental results demonstrate that MoS2 QDs can be used for biomedical imaging and drug delivery carriers.
Organic Skin Patch with Built-in Enzymatic Fuel Cell
Authors: Nishizawa Matsuhiko
Published: February 2020

We have developed totally organic electric patch with built-in enzymatic biofuel cell (BFC) for producing iontophoretic current flowing “on-skin” or “through skin”. The skin patches consist of stretchable enzyme electrodes, elastic conductive resistor, hydrogel sheet, and O2-permeable medical adhesive tape. We used fructose / O2 system because the enzymes for oxidation of fructose (fructose dehydrogenese) and reduction of O2 (bilirubin oxidase) can work without the presence of electron mediators for electrocatalysis, resulting in a simple configuration of the patch. The patch, when mounted on the skin, generates a transdermal ionic current with the osmotic flow from anode to cathode. I will present the results of two applications of the BFC patch. One is the transdermal dosing by the “through skin” current. The other is the wound healing by “on skin” current.

To improve delivery efficiency of skin patch, the iontophoresis induced by mild electric current (below 500 μA cm-2) has been used. The integration of a lightweight and safe power source would produce a more patient-compliant iontophoresis patch. Herein, we prove the BFC can drive iontophoresis, and realize totally disposable electric DDS patch.

Cells in the skin respond to electric current during a wound healing process. Taking advantage of this phenomenon, a stretchable bioelectric plaster is developed to generate ionic current along the surface of the skin by enzymatic electrochemical reactions. The bioelectric plaster fits to the skin and generates electric current above the wound for 12 hours to accelerate wound healing.

In addition to the above applications of BFC for generating iontophoretic flow, we have studied also the application of BFC for sensing medical information. I will present the results on the sensing of lactic acid in sweat and in interstitial fluid with the self-powered skin patches.

References: “Organic Transdermal Iontophoresis Patch with Built-in Biofuel Cell” Nishizawa et al., Advanced Healthcare Materials, 2015, 4, 506-510. “Accelerated Wound Healing on Skin by Electrical Stimulation with a Bioelectric Plaster” Nishizawa et al., Advanced Healthcare Materials, 2017, 6, 1700465-1700470.

Figure 1