bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Studies of Imidazolium Carboxylate Adducts in a Room-Temperature Ionic Liquid
Authors: Cheek Graham T. , Roeper Donald F. , Pearson Wayne , O'Grady William E. 
Published: February 2020

Introduction
Recent interest in carbon dioxide sequestration has prompted much research into ways of forming compounds from CO2 (1). One possible route for this process is reaction of CO2 with carbenes, which can be formed from the reduction of imidazolium cations (2). This paper reports recent results in this regard, carried out in a room-temperature ionic liquid.
Experimental
All electrochemical experiments were carried out in a Vacuum Atmospheres glovebox. Cyclic voltammograms were obtained on a PAR 283 potentiostat using PowerSuite software. Potentials are reported with respect to an Ag/AgCl reference electrode. X-Ray diffraction structure determinations were run on a Bruker AXS Kappa APEX-II. 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMI BF4 ) and 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate (BMPY TfO) were prepared by literature methods (3, 4).
Results and Discussion
The electrochemical properties of EMI BF4 were investigated in the room-temperature ionic liquid BMPY TfO. The EMI cation undergoes reduction at -2.2 V vs Ag/AgCl, followed by an oxidation process at -0.40 V on the reverse sweep. Introduction of CO2 into the solution results in a rather large increase in the reduction process at -0.40 V, suggesting that the EMI+ reduction product can interact with the added CO2 in a catalytic process. For comparison, CO2 reduction by itself in BMPY TfO occurs at -2.8V, so that the observed current increase at -0.40 V for the EMI+ / CO2 combination is not due to direct reduction of CO2. In order to identify the reaction products from the EMI+ / CO2 interaction, voltammograms of the imidazolium – carboxylate adducts, 1,3-dimethylimidazolium-2-carboxylate and 1,3-dimethylimidazolium-4-carboxylate, were run. The adduct structures were confirmed by X-ray structure determinations. The reduction of these adducts occurs at -2.6 V and -2.4 V, respectively, with an oxidation process at -0.35 V on the return sweep. These results support the formation of CO2 adducts with the EMI+ reduction product, probably a carbene.
References
(1) “Electrochemical CO2 Reduction on Metal Electrodes,” Y. Hori, Modern Aspects of Electrochemistry, Number 42, edited by C. Vayenas et al., Springer, New York, (2008).
(2) A. B. Bocarsly, Q. D. Gibson, A. J. Morris, R. P. L’Esperance, Z. M. Detweiler, P. S. Lakkaraju, E. L. Zeitler, and T. W. Shaw, ACS Catalysis, 2, 1684 (2012).
(3) S. Park and R. J. Kazlauskas, J. Org. Chem. 66, 8395 (2001).
(4) L. Crowhurst, N. L. Lancaster, J. M. P. Arlandis, and T. Welton, J. Am. Chem. Soc.,
126, 11549 (2004).
Electrodeposition of Palladium in 1-Butyl-3-Methylimidazolium Chloride Ionic Liquid
Authors: Shrestha Sujan , Gjoka Eriugen , Biddinger Elizabeth J. 
Published: February 2020

Ionic liquids (ILs) have superior electrochemical properties that make them ideal for electrodeposition (1, 2). These properties include higher conductivity than non-aqueous solvents, wide electrochemical window and high solubility of metal salts. Moreover, complications due to air or water reaction at a metal/IL interface could be readily managed in air and water stable ILs (2).
Electrodeposition of a metal is strongly affected by IL properties such as viscosity and conductivity which are depended upon its cations and anions (3). Cations also adsorb on the electrode surface and influence double layer structure at reduction potentials, while anions control the metal speciation (2). In addition, concentration of the dissolved metal ion affect the electrodeposition by changing the properties of ionic liquid and affecting the interactions at the metal/IL interface (2). Study of these phenomena on electrodeposition is limited (2).
In this work, electrodeposition of Pd ions in 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) and 1-butyl-3-methylimidazolium dicyanamide ([Bmim][DCA]) was investigated for fission palladium recovery application. Deposition properties are strongly depended upon the IL selected. For example, Figure 1a shows a Ni flag electrode immediately after Pd electrodeposition in [Bmim][DCA] at -0.9 V vs Fc/Fc+ for 2 h at room temperature. On the Ni substrate, black deposits of Pd particles were found which was washed away upon insertion into methanol (Figure 1b) suggesting that the Pd particles formed were loosely attached onto the Ni surface. More studies on the effect of the ILs and substrate on the electrodeposition of Pd will be presented.

Figure 1 (a) Black Pd particles on Ni flag electrode (0.25 cm2) after potential hold at -0.9 V vs Fc/Fc+ in 1-butyl-3-methylimidazolium dicyanamide at room temperature for 2 h. Pt wire served as the counter electrode. (b) Detachment of the Pd particles from the Ni electrode in methanol.

References

1. S. Z. E. Abedin, M. Polleth, S. A. Meiss, J. Janek and F. Endres, Green Chemistry, 9, 549 (2007).
2. A. P. Abbott and K. J. McKenzie, Physical Chemistry Chemical Physics, 8, 4265 (2006).
3. M. Galiński, A. Lewandowski and I. Stępniak, Electrochimica Acta, 51, 5567 (2006).
Effects of Process Conditions on the Fluidised Cathode Electrochemical Reduction of Tungsten Oxide in Molten LiCl-KCl Eutectic
Authors: Abdulaziz Rema , Brown Leon D , Inman Douglas , Simons Stefaan J. R. , Shearing Paul R , Brett Dan J. L. 
Published: February 2020

The direct electrochemical reduction of titanium oxide to titanium metal has been evinced by the FFC Cambridge process. [1] Numerous studies have been carried out to assess the performance and applicability of the process to the reduction of titanium, other refractory metals and metal alloys. However, there are some limitations to the FFC Cambridge process. For example, at least in the case of titanium, the current efficiency is quite low (10-40% to achieve 0.3% oxygen content in the final titanium product). [2]
There are two main reasons that hinder the reduction process: oxide product build-up in the electrolyte close to the surface and within the pores of the precursor, resulting in anomalous electro-migration of the oxygen vacancies, creating a barrier to the reduction process; and limited diffusion of the electrolyte within the precursor porous matrix. [3]
Thus, innovative new designs of the process are needed. The fluidised cathode process [4] offers a solution to these problems. Figure 1 is a schematic of the electrolytic cell used. The process is potentially applicable to the range of metals and molten salts systems and has been exemplified for the reduction of WO3 in LiCl-KCl eutectic. However, there is still much to be investigated to establish a full understanding and optimise the process. This paper discusses experimental findings of the effects the fluidisation rate and the void fraction have on the fluidised cathode applied to the Li-K-W-O-Cl system.
Figure 2. is a chronoamperogram of the process at different rates of fluidisation (argon flow rate). Coulometric analyses have been carried out to assert the extent of its effect. Electrochemical impedance spectroscopy (EIS) studies have also been conducted to establish the effects of the fluidisation rate and the void fraction (concentration of WO3 in the melt) on the diffusion properties between the working and counter electrodes.
Applications to more technologically relevant systems such as the electrochemical reduction of uranium oxide to uranium, as being investigated in the EPSRC REFINE consortium programme, are also discussed.
References:
[1] G. Z. Chen, D. J. Fray and T. W. Farthing, Nature, 407(6802), 361 (2000).
[2] C. Schwandt, D. T. L. Alexander and D. J. Fray, Electrochim. Acta, 54(14), 3819 (2009).
[3] E. Krasicka-Cydzik, ECS Trans., 50(11), 39 (2013).
[4] R. Abdulaziz, L. D. Brown, D. Inman, S. Simons, P. R. Shearing and D. J. L. Brett, Electrochem. Commun., 41(0), 44 (2014).
Carbon Fibers and Nanotubes as a Product of Interaction between Silicon Carbide and Carbonate Melt
Authors: Devyatkin Sergei Vladimirovich 
Published: February 2020

In quite a number of works, the corrosion of SiC with molten carbonates was studied, but the products of this interaction were not investigated [1, 2]. In this work, the interaction of silicon, TiC and SiC (F 14 and F 36) powders with Na2CO3-K2CO3 melt at 7500С in Ar atmosphere and in air was studied. After washing, the interaction products were analyzed on a SEM and by Raman spectroscopy. A thermodynamic evaluation of the reactions proceeding in carbonates showed that the Gibbs energy for reactions given below is negative at 1023 K; if follows that the reactions proceed from left to right:
I. 3Si + 2Na2CO3 = 2C + 4Na + 3SiO2

ΔGo
1023 K = -473 kJ
II. 3SiC + 2Na2CO3 = 5C + 4Na + 3SiO2

ΔGo
1023 K = -277 kJ
III. 3TiC + 2Na2CO3 = 5C + 4Na + 3TiO2

ΔGo
1023 K = -54 kJ
Were silicon interacts with carbonate melts, a large amount of graphite and carbon black is formed, which complicates the process of separation of reaction products. Because titanium oxides are slightly soluble in carbonate melts, the surface of carbon fibers was coated with this reaction product. Silicon oxide are readily soluble in carbonate melts, therefore the most promising method for the fabrication of carbon fibers and nanotubes is interaction between SiC and carbonate melts. When SiC interaction with molten carbonates, both carbon fibers and nanotubes are formed (Fig. 1.). Raman spectroscopy corroborated the presence of carbon fibers in the products.

References

1. R. E. Dial, G.E. Mangsen, Corrosion,
17, 35t
(1961).
2. R.E. Tressler, M.D. Meiser, T. Yonushonis, J. Am. Ceram. Soc.,
59, 278 (1976).
Fig. 1. SEM micrograph of SiC (F14) powder after 2 hours interaction with carbonate melts at 7500C .
Natural Fiber Welded Composite Yarns
Authors: Brown E. Kathryn , Durkin David P. , Fox Eric T. , Haverhals Luke M. , Sweely Kurt D. , De Long Hugh C. , Trulove Paul C. 
Published: February 2020

In this application, an ionic liquid (IL), specifically 1-ethyl-3-methylmidazolium acetate (EMIAc), well known for its ability to dissolve a variety of biopolymers1-3, is used in conjunction with molecular co-solvents to prepare biopolymer composite yarns by a process we call natural fiber welding (NFW). NFW uses controlled amounts of IL and a molecular co-solvent to swell and mobilize portions of the biopolymer substrate. By carefully selecting factors controlling NFW such as time, temperature and solvent system composition, partial dissolution occurs, mobilizing and redistributing only a small portion of the natural fibers and leaving much of the underlying substrate intact.4-7 This results in fibers with a shell of dissolved polymer, permanently adhered and hydrogen bonded to both the outer diameter of the fiber and (depending on the extent of welding) to the surface of adjacent fibers.
With the addition of a small amount of biopolymer into the IL solution, a NFW composite yarn can be created with the pre-dissolved biopolymer acting as an additional binder. Different combinations of biopolymer binder and substrate take advantage of the functional and structural benefits of both biopolymers. Binder can also be used to facilitate incorporation of functional materials (e.g., magnetic, electronic, photonic) into the yarn fiber matrix.

References

Swatloski, R. P.; Spear, S. K.; Holbrey, J. D.; Rogers, R. D. J. Am Chem Soc, 2002, 124, 4974.

Phillips, D. M.; Drummy, L. F.; Conrady, D. G.; Fox, D. M.; Naik, R. R.; Stone, M. O.; Trulove, P. C.; De Long, H. C.; Mantz, R. A. J Am Chem Soc., 2004, 126, 14350.

Xie, H.; Zhang, S.; Li, S. Green Chem.
, 2006, 8, 630.

Haverhals, L. M.; Reichert, W. M.; De Long, H. C.; Trulove, P. C. Cellulose, 2010, 2985, 425.

Haverhals, L. M.; Sulpizio, H. M.; Fayos, Z. A.; Trulove, M. A.; Reichert, W. M.; Foley, M. P.; De Long, H. C.; Trulove, P. C.Cellulose, 2012, 19, 13.

Haverhals, L. M.; Nevin, L. M.; Foley, M. P.; Brown, E. K.; De Long, H. C.; Trulove, P. C. Chem.Commun., 2012, 48, 6417.

Haverhals, L. M.; Brown, E. K.; Foley, M. P.; De Long, H.; Trulove P. ECS Trans, 2012, 50, 603.
A Strategy for Making Metal-Containing Ionic Liquids and Their Applications in Electrochemical Deposition
Authors: Dai Sheng 
Published: February 2020

Traditionally, ionic liquids are divided into two classes. The first ionic liquid, [C2H5NH3][NO3] (melting point13–14 ᵒC), was synthesized by Walden via the neutralization of ethylamine with concentrated HNO3, as reported in 1914.1 Because a proton-transfer reaction between an organic base and an acid is used during synthesis, this first class of ionic liquids is classified as protic ionic liquids. In 1951, Hurley and Wier reported new ionic liquids prepared by mixing alkylpyridinium chlorides with AlCl3.2 This work marked the genesis of the second class of ionic liquids, i.e., aprotic ionic liquids. The cations of the aprotic ionic liquids are derived from the alkyl–cation-transfer reaction between an organic base and an alkyl halide. Since then, many ionic liquids composed of various organic cations and inorganic or organic anions have been developed.3,4 Because there are large varieties of cations and anions available, their combination amounts to numerous potential ionic liquids. We have recently developed a third class of ionic liquids.5-7 The essence of our strategy is to synthesize the cations of ionic liquids via the metal–ion-transfer reaction between a neutral organic ligand and an inorganic salt. The key feature of this class of ionic liquids is that their cations consist of metal–ion complexes. These metal-containing ionic liquids provide not only ideal ionic environments, but also liquid inorganic precursors for electroplating of metals, gas separation, and synthesis of inorganic materials. The recent advances in this class of ionic liquids will be discussed.
Acknowledgment: This research was sponsored by the SERDP program.
(1) Walden, P. Bull. Acad. Imp. Sci.
1914, 8 405.
(2) Hurley, F. H.; Wier, T. P. Journal of the Electrochemical Society
1951, 98, 203.
(3) Welton, T. Chem. Rev.
1999, 99, 2071.
(4) Wasserscheid, P.; Keim, W. Angew. Chem.-Int. Edit.
2000, 39, 3773.
(5) Huang, J. F.; Luo, H. M.; Dai, S. Journal of the Electrochemical Society
2006, 153, J9.
(6) Zhu, H. G.; Huang, J. F.; Pan, Z. W.; Dai, S. Chem. Mat.
2006, 18, 4473.
(7) Ma, Z.; Yu, J. H.; Dai, S. Adv. Mater.
2010, 22, 261.
Novel Pathways for Improving the ORR Rate
Authors: Snyder Joshua David , Kang Yijin , Strmcnik Dusan , Li Dongguo , Markovic Nenad M , Stamenkovic Vojislav R 
Published: February 2020

Technologies such as fuel cells and lithium-air batteries rely on electrochemical processes that need to provide satisfactory energy density; however, a major challenge lies in the insufficient activity and durability of materials that are currently employed as cathode catalysts for electrochemical reduction of oxygen. These limitations inevitably lead to a lower operating efficiency of the devices, which highlights the need for development of more active and durable oxygen reduction reaction (ORR) catalysts. Consequently, the majority of research efforts are placed on the catalyst design and synthesis aiming to improve their efficiency. It has been found that properties such as surface structure, surface and subsurface composition associated with electronic properties have distinguished roles in determining functional properties of electrocatalysts 1. In this report the material-by-design-approach, would be used to demonstrate how the knowledge obtained from the well-defined surfaces can be employed to create tailor-made practical catalysts with advanced catalytic properties 2. Considering the fuel cells, most of the research is centered on platinum, the best monometallic catalyst for the ORR. However, multimetallic systems could provide additional benefits by bringing together highly diverse constituents to alter and tune both catalytic activity and durability of the catalysts 3.
In addition to the catalyst's material it is of paramount importance to emphasize the role of liquid phase which is influencing on the overall properties of an electrified interface. Molecular species from employed electrolyte and the nature of their interaction with the catalyst surface can be also used in tuning the catalytic performance. More recently, it was also demonstrated that molecular patterning could be used as a tool that can induce selectivity of the electrocatalyst 4.
[1] Stamenkovic et al. Science315 (2007) 493.
[2] Stamenkovic et al. Nature Materials6 (2007) 241.
[3] Wang et al. Nano Letters11 (2011)919.
[4] Genorio et al. Nature Materials 9 (2010) 998.
Highly Tunable and Ordered Graphene-Oxide-Based Materials for Energy Applications
Authors: Martinez Ulises , Mohite Aditya , Purdy Geraldine M , Dattelbaum Andrew M , Zelenay Piotr , Gupta Gautam 
Published: February 2020

Carbon materials are an integral part of devices including fuel cells, super-capacitors, and batteries. Current technologies are marred with issues such as long-term durability under high potentials (e.g., fuel cells), low energy/power density (super capacitors), and metal intercalation issues (batteries). State-of-the-art devices have typically been synthesized from highly heterogeneous precursors and amorphous carbon materials. Materials based on graphene and graphene-oxide (GO) are more homogeneous and possess properties, such as good chemical stability, excellent conductivity, and more importantly, can be functionalized in a controlled manner. These unique properties have led to explosion in research in areas of graphitic materials as catalyst support/material for oxygen reduction reaction (ORR) and high energy density thin film super capacitors.
In this study, we report the synthesis of highly structured GO based materials prepared using Hummers method. We specifically target the control of functional groups and d-spacing of GO materials using drying and solvent treatments. XPS, FTIR and XRD studies were used to unravel the structure-function correlation of the resulting materials. The synthesized graphene oxide structures were further subjected to reduction and doping in different conditions to obtain an optimum energy storage/support material. Although most reduced materials possess similar structural properties, they have a variable electrochemical performance and stability. In this study we obtain a fundamental understanding of the effect of pre-treatment on the structure and function of reduced materials.
We specifically study these materials for oxygen reduction reaction and super capacitors. In a 0.5 M H2SO4 electrolyte, a shift in half wave potential and decrease in peroxide production is obtained depending upon the graphene oxide treatment. These catalyst materials perform well in an alkaline electrolyte as well. These catalyst systems are highly durable and a drop of less than 30 mV drop was obtained over 2000 cycles in acid electrolyte in presence of oxygen indicating the role of high graphitic content in providing stability. Furthermore, we identify that the pyridinic nitrogen content is important for high electrochemical activity. We also demonstrate high power density super capacitors obtained using similar pretreatments.

Acknowledgment

Financial support from the Los Alamos National Laboratory Laboratory-Directed Research and Development (LDRD) Program is gratefully acknowledged.
Porosification of Silicon from the Viewpoint of Nonlinear Dynamics
Authors: Fukami Kazuhiro 
Published: February 2020

Anodic dissolution of silicon in HF solutions leads to formation of porous silicon. Formation of a wide variety of porous structures has been reported. In the course of the studies, electrochemical oscillations have been found in silicon anodization. Because a symmetry breaking is necessary for the formation of porous silicon, such oscillatory phenomena have attracted keen attention for the understanding of porous silicon formation.
Formation of macroporous silicon, whose pore diameter is several micrometers, has been explained based on the current burst model proposed by Föll and his colleagues. In the current burst model, macropore formation has been explained based on desynchronization of local oscillators on a silicon surface.Recent studies on nonlinear dynamics in electrochemistry have shown that spatiotemporal pattern formation is closely related to a negative differential resistance (NDR) observed in the current density vs. potential curve. However, NDRs have not been considered in porous silicon formation so far. We have focused our attention on the emergence of NDR in anodization of silicon, and have discussed the spatial pattern formation on silicon.
Recently, we have found that a clear S-shaped NDR is observed after the correction of iR-drop in the electrolyte solution, when using an HF solution containing alcohol such as 2-propanol. In the S-shaped NDR region, an array of microgrooves is spontaneously formed on the silicon surface. Since an S-shaped NDR is induced by a positive feedback which is independent on electrode potential, while electrode potential plays a role of an negative feedback. In the present case, we think that the microgroove array is induced by Turing instability. According to earlier studies, the size of Turing patterns observed in electrochemical systems is on the scale of millimeters. Astonishingly, the size of the present Turing pattern is on the scale of micrometers. In the present paper, the reason why the characteristic size is so small will be discussed in detail. In addition to the Turing pattern formation, formation of other spatiotemporal patterns in silicon electrochemistry, which is difficult to be explained in the classical framework of spatiotemporal pattern formation in electrochemistry, will be discussed.
Electrochemical Regulation of the Cyanobacterial Circadian Oscillation
Authors: Nakanishi Shuji , Hashimoto Kazuhito 
Published: February 2020

There has been a growing awareness of a close relationship between circadian oscillation and intracellular redox state in diverse species ranging from cyanobacteria to mammals [1]. The elucidation of this relationship is of physiological importance since malfunction and disruption of the circadian clock can threaten the wellbeing of living organisms. Here we report that the circadian oscillation of the cyanobacterium Synechococcus elongatus PCC7942, the simplest organism found to exhibit circadian oscillation,can be entrained by periodical modulation of the intracellular redox state via electrochemically controlled-extracellular electron transfer (EC-EET), a process in which intracellular electrons are exchanged with extracellular electrodes [2].
In-vivo monitoring of chlorophyll fluorescence revealed that the redox state of plastoquionone pool could be controlled by EC-EET with simply changing the electrode potential in the presence of biocompatible electron mediators. As a result, the endogenous circadian clock of S. elongatuscells was successfully entrained through periodically modulated EC-EET by emulating the natural light-and-dark cycle, even under constant illumination conditions. This represents the first example of regulating the biological oscillation via intracellular redox state by electrochemical technique.
[1] S. Edgar et al.,
PNAS10.1073. (2012).
[2] Y. Lu et al.,
Angew. Chem. Int. Ed., 53, 2208-2211 (2014).