bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Fast-Scan Nanogap Voltammetry at Double-Carbon-Fiber Ultramciroelectrodes
Authors: Amemiya Shigeru 
Published: February 2020

In this presentation, we discuss theory [1] and experiment [2] of double-carbon-fiber (CF) ultramicroelectrodes (UMEs) with nanometer-wide gaps to voltammetrically obtain high time resolution, signal-to-background ratio, and kinetic selectivity for dopamine (DA) against ascorbic acid (AA). The novel nanogap-based electrodes are fabricated by using a pair of ~7 µm-diameter CFs, which are inserted into a double-bore glass capillary, heat-pulled, and milled by focused-ion-beam technology to yield ~50 µm-long double-cylinder UMEs separated by a nanometer-wide gap without extensive nanolithography or nanoscale electrode positioning required for other nanogap electrodes. Double-CF UMEs are characterized electrochemically by investigating the redox cycling of the Ru(NH3)6
3+/2+ couple across a nanogap between voltammetric generator and amperometric collector electrodes to achieve quasi-steady states at fast scan rates of 100 V/s, which is ~1000 times faster than reported with any nanogap-based electrochemical cell. Importantly, the transient background of the amperometric collector response is suppressed ~100 times in comparison with that of the voltammetric generator response to enable the quantitative analysis of the collector response against the cycled generator potential without background subtraction. Finite element analysis of oxidative amperometric responses to Ru(NH3)6
2+ at the collector electrode at up to 100 V/s yield consistent gap widths of ~0.18 µm and a standard electron-transfer rate constant of 0.9 cm/s. Moreover, nanogap-mediated redox cycling can be initiated by DA oxidation at the generator electrode to largely improve the DA selectivity of the collector response against AA, which is also oxidized at the generator electrode to immediately and irreversibly produce a redox-inactive species, thereby minimizing the corresponding collector response. The probe-type design of double-CF UMEs as well as their high DA selectivity against AA is attractive for in-vivo applications.
[1] Pathirathna, P.; Balla, R. J.; Amemiya, S. “Simulation of fast-scan nanogap voltammetry at double-cylinder ultramicroelectrodes.” J. Electrochem. Soc., Focus Issue on the Brain and Electrochemistry Honoring R. Mark Wightman and Christian Amatore, 2018, 165, G3026.
[2] Pathirathna, P.; Balla, R. J.; Amemiya, S. “Nanogap-based electrochemical measurements at double-carbon-fiber ultramicroelectrodes.” Anal. Chem.
2018, 90, 11746.
Long Life Fully Reversible Lithium-CO2 Battery
Authors: Ahmadiparidari Alireza , Curtiss Larry A , Salehi-Khojin Amin 
Published: February 2020

Although far less studied, lithium-CO2 (Li-CO2) batteries are attractive energy storage systems for fulfilling the demand for the future large-scale applications such as electric vehicles and grid systems due to their higher specific energy density (~1876 Wh/kg) compared to those of commonly used lithium-ion (~265 Wh/kg) and lead-acid (~30-40 Wh/kg) batteries. However, the major challenges with these batteries are the low cyclability and poor reversibility of discharge products (e.g., Li2CO3 and carbon) during the battery cycling. An ideal system must operate in carbon neutral conditions in order to reversibly balance the electrochemical reactions during discharge and charge processes.
In this work, using molybdenum disulfide nanoflakes as a cathode catalyst combined with an ionic liquid and dimethyl sulfoxide hybrid electrolyte, we have obtained a Li-CO2 battery with a long cycle life while maintaining a carbon neutrality in the system. The battery shows a superior cycle life of 500 for a fixed 500 mAh/g capacity per cycle and a remarkable deep discharge capacity of 60,000 mAh/g, which are by far the best cycling stability and highest capacity reported in Li-CO2 batteries, respectively. The presented Li-CO2 battery system demonstrates for the first time that C-O bond making and breaking chemical transformations can be used in energy storage systems with a long cycle life, in addition to the widely studied alkali metal (Li, Na, K) – oxygen bond making and breaking transformations. Theoretical calculations are used to provide insight into the reaction mechanisms for the reversible formation and decomposition of the products during the discharge and charge processes. The achievement of a reversible, long cycle life Li-CO2 battery helps to improve Li-CO2 chemical performance and energy storage systems.
Possibility of Using Petroleum Coke As Reducing Agent for V2O5 in Solid-Phase Synthesis of Li3V2(PO4)3
Authors: Kuzmina Elena , Isyangulov Ilgam , Chudova Nadezhda , Prosochkina Tatyana , Karaseva Elena , Kolosnitsyn Vladimir 
Published: February 2020

Nowadays, electrochemical batteries are playing an important role in the development of technology in various fields – consumer electronics, electric transport, and stationary energy storage systems. The main requirements for modern batteries are high specific energy and low cost. State of art lithium-ion batteries have the highest specific energy, but their cost is quite high, and that limits their production volume. Therefore, a relevant problem is the development of new low-cost electrode materials with a high specific energy.
One of the most promising compounds for positive electrodes of lithium-ion batteries is lithium vanadium phosphate Li3V2(PO4)3. It has the same safety in operation as LiFePO4, and at the same time has a higher specific capacity of 197 mA·h/g vs. 170 mA·h/g in LiFePO4, and provides lithium-ion batteries higher average discharge voltage. The lithium-ion batteries with positive electrodes based on Li3V2(PO4)3 have an average discharge voltage of 4.1 V and with LiFePO4 have 3.3 V [1].
The main raw material for lithium-vanadium phosphate is vanadium pentoxide (V2O5). V5+ reduces to V3+ in the process of synthesis Li3V2(PO4)3.
The aim of the present work was to study the possibility of using petroleum electrode coke as a reducing agent in the solid-phase synthesis of lithium vanadium phosphate Li3V2(PO4)3.
The following reagents were used: Li2CO3 (>99.9%), NH4H2PO4 (>98%), V2O5 (>99%), petroleum electrode coke. The reagents were milled to a homogeneous mixture in a mortar, then pressed into pellets in a hydraulic press at a pressure of 6 tons per cm2. The synthesis was carried out at a temperature of 800 °C in a tubular furnace in an argon atmosphere for 5 hours. Electrodes of the following composition (% wt.) were made of the synthesized material: 80% Li3V2(PO4)3, 10% Super P, 10% LA-132. 1M LiPF6 in mixture of DMC:EMC:EC:PA (1:1:2:1 by vol.) was used as an electrolyte, Celgard®3501 was used as a separator, lithium metal foil (100 µm) was used as the negative electrode.
On the 1st cycle, the discharge capacity of the cells was 130 mA∙h/g(Li3V2(PO4)3) for cells being cycled in the potential range of 3.0-4.2 V and 160 mA∙h/g(Li3V2(PO4)3) in the range of 3.0-4.8 V.
According to obtained results, it can be concluded that petroleum electrode coke can be used as a reducing agent in the solid-phase synthesis of Li3V2(PO4)3. In order to improve the characteristics of Li - Li3V2(PO4)3 cells, it is necessary to optimize the synthesis method.
This work was performed as part of a Government Order to Ufa Institute of Chemistry of the Russian Academy of Sciences by the Ministry of Science and Higher Education of the Russian Federation (Theme No. AAAA-A17-117011910031-7), Russia.

References

[1]. S.W. Choi, Da. H. Kim, S.H. Yang, M.Y. Kim, M. S. Lee, Journal of Industrial and Engineering Chemistry,
52 (2017), 314-320.
(Invited) Formation, Characterization and Applications of Nanowire Films Formed By Anodizing of Metals
Authors: Habazaki Hiroki , Wada Keisuke , Zhu Chunyu , Aoki Yoshitaka 
Published: February 2020

Anodizing of metals and alloys is a simple electrochemical process to form various nano-structured oxide films, including self-ordered nanoporous and nanotubular films. Typical examples are nanoporous alumina films with honeycomb morphology and nanotubular array of anodic titanium oxide. Recently, several nanowire-type anodic films have been prepared on metals, including aluminum, copper and zinc. The formation mechanism of of the nanowire films may be different from those of the nanoporous and nanotubular anodic films. Here, our recent studies on the formation, characterization and applications of the anodic nanowire films on metals are presented.
When zinc plate was anodized at a constant voltage in KHCO3 aqueous electrolytes, nanowires were covered on the entire zinc surface. From the SEM observations, it was found that pits were initially formed on zinc surface. The low-voltage SEM observations disclosed that some small pits were covered with a thin passive film, and in such pits nanowires were preferentially nucleated probably because of the increased concentration of dissolved Zn2+ ions in the pits. Then, the nanowires were grown radially over the pits and covered the entire zinc surface.
The nanowires were not composed of ZnO. XPS and FT-IR analyses of the nanowire films indicated the presence of carbonate and hydroxide species; the nanowire consisted of basic zinc carbonate. TEM observations confirmed the single crystalline nature of the as-formed nanowires. The basic zinc carbonate was converted to ZnO without changing the nanowire morphology by heat treatment in air, although single crystalline nanowires changed to polycrystalline one. In addition, slit-type nanopores were introduced into the nanowires so that the specific surface area of the nanowire films was highly enhanced by the heat treatment.
The nanowire films exhibits unique wettability to liquids. The as formed nanowire films showed superhydrophilicity with a water contact angle close to 0o and after organic coating the surface changed to superhydrophobic with a water contact angle greater than 150o. Such surface may have many potential applications.
Mg Thin Film Pit Growth and Anomalous Hydrogen Evolution
Authors: D avila Gabbardo Aline , Viswanathan Gopal B , Frankel Gerald S. 
Published: February 2020

New technologies and applications for Mg require further improvements of its corrosion resistance. Fundamental comprehension of the Mg corrosion mechanisms is necessary to address the issue, as the Mg corrosion behavior is unexpected from the theory of electrochemical kinetics. The anomalous hydrogen evolution phenomenon (anomalous HE) exhibit by Mg, also known as the negative difference effect (NDE), is still an unresolved issue. Recent research suggests that the anomalous HE is a consequence of a surface change during dissolution. The proposed mechanisms debate the location of the phenomenon on the surface. The phenomenon is proposed to happen at the corroded areas behind the corrosion front, in the dark corrosion products left behind the corrosion front and/or at the active dissolving sites. New techniques and experimental data are needed to further address the discussion.
In this work, the 2D pit growth method is used to study the anomalous HE phenomenon on Mg with the aim to provide further experimental evidence towards an explanation. The method is called 2D pitting because the sample is a thin metallic film deposited on an inert substrate, so the pit depth is constant and limited to the film thickness. By analyzing 2D pit growth, it is possible to accurately track the active dissolving surface and to measure the anodic, net and cathodic current densities. The hydrogen evolution current density was shown to increase with increasing applied potentials in the ohmic/activation control region, which is direct evidence for the anomalous HE behavior. In addition, the results clearly demonstrated that the anomalous HE phenomenon happens at the active dissolving site, which in this case is the 2D pit wall. Anomalous HE did not occur at the corroded areas behind the corrosion front, which in the case of a 2D pit is the inert substrate. It also did not occur in the corrosion product, which in this case was broken and lifted out by the hydrogen bubbles being electrically disconnected from the Mg matrix. The 2D pits were also evaluated at high applied potentials where a salt film precipitated on the active dissolving surface. The results showed that the anomalous HE rate decreased in the transport control region approaching zero at the limiting current density. In this case, the rate of hydrogen evolution was limited by water diffusion through the salt film to reach the active surface. It was also shown by TEM/EDX analysis that impurities do not accumulate at the pit wall and cannot account for anomalous HE. The results support the idea that the actively dissolving Mg surface is the site of anomalous HE, and that, in the absence of a salt film, the dissolving surface is extremely catalytic to the HE process.
Electrochemical Investigation of Oxygen Reduction Reaction on Type 316L Stainless Steel in NaCl Solutions in a Confined Space
Authors: Tada Eiji , Jang Junho , Ooi Azusa , Nishikata Atsushi 
Published: February 2020

Steel plate joints are commonly produced in the manufacturing process of steel structures such as automobiles and bridges. The steel plate joints suffer from aqueous corrosion in atmospheric environments. Especially, severe corrosion is often observed in the confined spaces between the steel plates because aqueous electrolytic solutions can be kept in the spaces. In this case, corrosion reaction rate of the steels in the confined space is basically controlled by the reduction reaction rate of dissolved oxygen. Therefore, it is important to estimate oxygen reduction reaction rate in the confined spaces to predict corrosion deterioration of steel plate joints. In this study, electrochemical investigation of oxygen reduction reaction rate in a confined space was performed.
The material used in this study was austenitic stainless steel type 316L bar with various diameters from 5 to 20 mm. The type 316L bar was cut into a small cylindrical piece and the piece was embedded in epoxy resin after being contacted with a lead wire. The surface of the embedded stainless steel sample was ground with SiC papers down to JIS200 grit and then cleaned ultrasonically in EtOH. Test solutions were aqueous NaCl of different concentrations from 0.05wt% to 5wt%. The solutions were prepared with Milli-Q water and reagent grade sodium chloride.
For the electrochemical measurements, the sample was set horizontally in a plastic vessel and then an acrylic rod of 20 mm in diameter, which was used as a crevice former, was placed above the sample surface to make a confined space between the sample and the rod. The gap between the sample surface and the rod was changed from 20 um to 200 um by using a laser displacement meter. Electrochemical measurements were conducted by a conventional three electrode method with a platinum wire (Pt) and a Ag/AgCl in a saturated KCl (SSE) as a counter electrode (CE) and a reference electrode (RE), respectively. Cathodic polarization curves for the sample were measured with various gaps at a potential sweep rate of 0.5mV/s.
Cathodic polarization behavior for the sample measured in the confined spaces was similar as that measured in a bulk solution; a limiting current region due to oxygen reduction reaction was observed on the samples of various diameters in a confined space. It was confirmed that the limiting current density decreased with decreasing in the gap. This is attributed to be the difference in the oxygen diffusion rate on the sample in the confined space.
(Invited) Phase Change Materials for Non-Volatile Memories : Properties and Optimization through Ab Initio Simulation
Authors: Raty Jean-Yves 
Published: February 2020

Phase Change Materials are emerging as active components of non-volatile memories thanks to their ability to switch extremely rapidly from a conducting crystal to a more semiconducting glassy. Using Ab Initio simulations, we address the structure and some properties of the glassy phase, like aging, but also go back to the description of bonding in the crystalline phase.

We develop a two-dimensional map based on a quantum-topological description of electron sharing and electron transfer in binary solids. This map intuitively identifies the fundamental nature of ionic, metallic, and covalent bonding in a range of elements and binary materials. Furthermore, it highlights a distinct region where phase change materials are found and for which bonding has been qualified as ‘metavalent’ [1,2]. Extending this map into the third dimension by including physical properties of application interest, we show that bonding in metavalent compounds differs from the our usual views of bonding. This map could be used to help designing new materials: by searching for desired properties in a 3D space and then mapping this back onto the 2D plane of bonding.

[1] J.Y. Raty, M. Schumacher, P. Golub, V. Deringer, C. Gatti and M. Wuttig Advanced Materials, (2018) 1806280
[2] M. Wuttig, V. Deringer, X. Gonze, C. Bichara and J.Y. Raty, Advanced Mater. (2018) 1803777
Work funded by F.R.S.-FNRS & the Region Wallonne (CECI Tier-1) and the Federation Wallonie-Bruxelles (ARC AIMED)
Molybdenum Electrorefining in Ionic Liquids
Authors: Gunnell Ethan Mitchel , Avery Ashley , Ying Andrew , Gunnell LaGrande , Stoddard Michael , Memmott Matthew , Harb John N. 
Published: February 2020

Molybdenum is a valuable refractory metal used to harden and protect metal alloys. Additionally, certain nuclear reactors can be used to produce Mo99, a valuable radioactive isotope with important medical applications. To qualify for medical use, the isotope must be isolated in high purity molybdenum. One method of metal purification is electrorefining. Electrorefining consists of anodically dissolving a target metal of inadequate purity, and then depositing it onto a substrate at a higher purity. Conventional aqueous-based electrolytes are not suitable for Mo electrorefining owing to their instability in the potential range needed for Mo deposition and the tendency of molybdenum to form insoluble oxides. Ionic liquids offer the wider electrochemical window needed to process Mo. Such liquids are often referred to as ‘designer solvents’ due to the plethora of possible constituents that can render different properties. The purpose of this study was to explore Mo electrorefining in ionic liquids, and to identify solvents with properties suitable for this type of molybdenum purification.
In this study, the effectiveness of molybdenum electrorefining was examined in a few different ionic systems, including choline-chloride-based deep eutectic systems. Cyclic voltammetry was utilized to determine oxidation and reduction potentials given against an Ag/Ag+ reference electrode. Deposits were characterized with EDX and morphologies examined with SEM. Furthermore, faradaic efficiencies and methods for optimizing deposition were determined.
Our findings show that the effectiveness of a solvent for Mo electrorefining is determined by the coordinating nature of the solvent. Weakly coordinating ligands, such as BF-
4, are not ideal for electrorefining because Mo ion replenishment via anodic dissolution is inhibited by low solubility. Ethylene glycol-choline chloride, which is more strongly coordinating, has shown effective dissolution at room temperature. In addition, deposition has been observed in this DES at temperatures above 80° C with aggressive stirring, indicating that it is transport controlled. Despite low faradaic efficiencies for deposition, deposit morphology and adherence can be improved through pulse deposition. This is believed to be the first report of molybdenum deposition or electrorefining in a deep eutectic solvent.
Characterization Capacitive Desalinzation Cell By Using the FeIII(CN)6
3-/FeII(CN)6
4- Redox Couple As an Electrochemical Probe
Authors: Sene Assane , Daffos Barbara , Taberna Pierre-Louis , Simon Patrice 
Published: February 2020

Recently, a desalination technique based on porous carbon has been reported [1], merging together desalination process with electrochemical energy storage. Thanks to this new strategy, an important step forward, respect to other water desalination technologies, has been achieved. The principle is based on the capacitive adsorption of Na+ and Cl- ions in the pores of a porous activated carbon, constituting the active material of an electrochemical double layer capacitor electrode. Differently from conventional EDLC, the active material is made in the present case as slurries flowed through an electrochemical cell to achieve a continuous desalination of seat water; such system has been named Electrochemical Flow Capacitor (ELC) [2], [3].
The objective of the study is to improve the energy efficiency of the desalination process by optimizing the cell design and by selecting the proper activated carbon. To do so, we characterized a desalinization cell using different type of electrodes using the FeIII(CN)6
3-/FeII(CN)6
4- redox couple as an electrochemical probe. Our approach allowed to define a dimensionless number θ, which is proportional to the flow rate and inversely proportional to the potential scan rate, giving a guideline to sort out different operating regimes in the flow cell. Two operating regimes have been evidenced: a permanent regime for θ > 60, allowing for higher and efficient charge adsorption, and a non-permanent domain for θ < 60.

Références :

[1] M. E. Suss, S. Porada, X.Sun, P. M. Biesheuvel, J. Yoon and V. Presser, Energy Environ Sci., 20015, 8, 2296-2319.
[2] K. B. Hatzell, E. Iwama, A. Ferris, B. Daffos, K. Urita, T. Tzedakis,F. Chauvet, P. Taberna, Y. Gogotsi, P. Simon, Electrochemistry Communications 43 (2014) 18–21.
[3] Y. Gendel, A. K. E. Rommerskirchen, O. David, M. Wessling, Electrochemistry Communications 46 (2014) 152–156.
(Invited) Thin Film Batteries Still Have Interesting Lessons for Lithium Batteries
Authors: Dudney Nancy J. , Westover Andrew S. , Veith Gabriel M. , Chi Miaofang , Kalnaus Sergiy 
Published: February 2020

After several decades of R&D, the thin film batteries using ORNL’s Lipon glassy electrolyte is still a promising technology for consumer electronics. These batteries also serve as model systems for other solid-state battery efforts, as the thin film batteries demonstrate exceptional stability with extended cycling and wide ranges of voltage and temperature. In light of recent thermodynamic analysis [1], we need to ask - Are we cheating thermodynamics? This presentation will briefly review the early work on Lipon-based batteries leading into recent efforts to advance the understanding of Lipon properties. Results for stability of Lipon with high voltage cathodes and Li metal will be highlighted.
[1] William D. Richards, Lincoln J. Miara, Yan Wang, Jae Chul Kim, and Gerbrand Ceder, DOI: 10.1021/acs.chemmater.5b04082
Acknowledgement: This work is based on support from the US Department of Energy, Advanced Research Projects Agency for Energy (ARPA-E) IONICS program; and on earlier support from U. S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division.