bluuebunny/crossref_metadata_2025 huggingface dataset:
Noble Metal Nanoparticle for Oxygen Electroreduction: Size, Shape, Ligand and Composition Effects
Authors: Tang Zhenghua , Wang Likai , Yang Hongyu , Wang Qiannan , Yan Wei , Chen Shaowei
Published: February 2020

Noble Metal Nanoparticles (e. g. Au, Pd, or Alloy) have been attracting continuous research interests in electrocatalytic field in the past decade, thanks to their remarkable catalytic reactivity towards oxygen reduction, hydrogen evolution, dioxide reduction, water oxidation and so on. Nanocomposites based on ultrasmall gold nanoclusters Au102(p-MBA)44 and porous carbon nanosheets have been fabricated and employed as highly efficient electrocatalysts for ORR. Molecular clusters Au25(SC2H4Ph)18, Au38(SC2H4Ph)24 and Au144(SC2H4Ph)60 have been synthesized, and loaded into porous carbon to obtain hybrid materials. The as-prepared nanocomposites demonstrated excellent reactivity for ORR, and strong core size effects were established. On the other hand, peptide capped Pd nanoparticles have been directly utilized as catalyst for ORR, and the peptide sequence were found to play a very important role in tuning the catalytic reactivity. Meanwhile, the nanoparticle shape and morphology was manipulated by tuning the peptide-to-metal ratio, and shape effects on ORR were examined as well. Finally, PdAu alloy nanoparticles have been fabricated and the composition were optimized to maximizing the electrocatalytic reactivity.
(Invited) Theoretical Investigation on Proton Conductance Mechanism in Proton Exchange Membranes
Authors: Tsuneda Takao
Published: February 2020

The hydrated structures of the proton exchange membranes were theoretically investigated using long-range corrected density functional theory [1,2] to make clear why perfluorinated polymer membrane Nafion is superior to other membranes in the proton conductivity at low humidity and consequently to reveal the proton conductance mechanism in low-humidity membranes, which are significant for anti-freezing. First, we compared the hydration structures of Nafion and multiblock sulfonated poly(arylene ether sulfone)s (SPE) hydrocarbon membranes for various hydration numbers. As a result, we found the relay mechanism of not protons but protonated water clusters between the sulfonic acid groups may contribute to the high proton conductivity of Nafion with less-hydrated sulfonic acid groups. In the relay mechanism (Fig.), protonated water clusters are relayed by the side chains through the doubly-hydrated sulfonic acid groups. We also examined the infrared (IR) spectrum calculations of Nafion to figure out its hydration structures at low humidity [4]. Consequently, we found that the experimental IR spectrum behaviour for various humidity conditions strongly supports the relay mechanism, because it is consistent only with the IR spectrum behaviour of the doubly-hydrated sulfonic acid groups, in which protons are detached beforehand. Based on the relay mechanism, we have also examined the proton conductance of state-of-the-art block co-polymer membranes that provide high proton conductance comparable to that of Nafion [5]: Sulfonated poly ketone (SPK) [6] and Sulfonated poly (p-phenylene) (SPP) [7] membranes. As a result, we found that these membranes have similar detachment abilities of protonated water clusters to that of Nafion, though they give slightly lower proton detachment abilities than that of Nafion.

H. Iikura, T. Tsuneda, T. Yanai and K. Hirao, J. Chem. Phys. 115, 3540 (2001).

T. Tsuneda, Density Functional Theory in Quantum Chemistry (Springer), (2014).

R. K. Singh, T. Tsuneda, K. Miyatake and M. Watanabe, Chem. Phys. Lett.
608, 11 (2014).

R. K. Singh, K. Kunimatsu, K. Miyatake, and T. Tsuneda, submitted.

R. K. Singh, K. Miyatake, and T. Tsuneda, in preparation.

T. Miyahara, T. Hayano, S. Matsuno, M. Watanabe, and K. Miyatake, ACS Appl. Mater. Interfaces
4, 2881 (2012).

J. Miyake, T. Mochizuki and K. Miyatake, ACS Macro Lett.
4, 750 (2015).

Figure 1
Designing IrO2 Nanoparticles for Oxygen Evolution
Authors: Sen Fatih G. , Kinaci Alper , Narayanan Badri , Davis Michael J. , Gray Stephen K. , Sankaranarayanan Subramanian K. R. S. , Chan Maria K. Y.
Published: February 2020

IrO2 is one of the most efficient electrocatalyst for the oxygen evolution reaction (OER) and water splitting process for the efficient solar energy into fuel (H2) generation. In solar fuels, IrO2 is used in the form of supported nanoparticles and its catalytic activity strongly depends on the size and shape of nanoparticles. Atomistic modeling of IrO2 nanoparticles with different sizes and shapes can enable fundamental understanding of catalytic processes govern at nanoparticle surfaces. Here, we used density functional theory (DFT) and variable charge force field calculations to study catalytic activity changes at the surfaces, edges and corners on the nanoparticle. We used O adsorption energy as a descriptor for the catalytic activity for water splitting reaction and determined the activity changes with respect to atomic coordination and charge transfer at different active sites on the nanoparticle. Calculations with the developed variable charge force field enable investigation of thermodynamic stability of relatively large (up to 2 nm) IrO2 nanoparticles with different shapes. We construct a metric to describe the overall catalytic activity of a nanoparticle and describe the effects of nanoparticle shape and size on the catalytic activity in terms of surface coordination changes, charge transfer and structural stability. Our results will shed light on the design and development of stable nanoscale IrO2 nanoparticle electrocatalytsts that efficiently utilize solar energy for water splitting reaction.

ACKNOWLEDGEMENT: Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The submitted abstract has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
Electrochemistry with Ion Transfer Processes at Microhole-Liquid/Gel Interfaces for Sensing Applications
Authors: Lee Hye Jin
Published: February 2020

There have been extensive efforts made on developing highly sensitive and selective electrochemical sensing technologies for a wide spectrum of environmental, biological and food research applications. In this talk, we will discuss our latest achievements made on creating electrochemical sensing platforms composed of microhole supported-water/gel interfaces (micro-ITIES) for the highly selective and sensitive detection of environmentally toxic and pharmaceutical reagents. A single or an array of microholes fabricated on a thin polymer film (e.g., polyethylene terephthalate) was filled with a hydrophobic polyvinylchloride-nitrophenylocytylether (PVC-NPOE) gel to create microhole-ITIES. For example, a Cu(II) ion selective sensor was designed utilizing the assisted transfer reaction of Cu(II) by a novel Cu(II) selective ionophore, picolinamide-PV in the gel layer [1]. In addition, sodium, potassium and calcium selective sensing platforms incorporating each target selective ionophores in the gel was developed for ion analysis in biological fluids including urine, serum and plasma [2]; the concentration of each ions was determined by measuring the current associated with the transfer of Na+, K+ and Ca2+ across the microhole-ITIES assisted by dibenzo-18-crown-6, valinomycin and ETH-129, respecively. These sensors can also be fabricated on a disposable sensing chip platform for convenient field applications. Last example is the use of microhole-ITIES for developing selective sensing platforms for pharmaceutical drugs such as topotecan [3], doxorubicin, tetracycline, levofloxaxin in biological fluids and stream and river water samples. In order to enhance the sensitivity of the sensors, differential pulse stripping voltammetry was used via holding the transferring potential of each analytes for a certain time to enrich the target ions in the gel layer followed by stripping of the ions from the gel to water phase. Lastly, future aspects of microhole-ITIES for ion sensing applications will be discussed.

 

References

[1] S. H. Lee, J. Sumranjit, P. Tongkate, B. H. Chung, H. J. Lee. Eelectrochim. Acta. 123 (2014) 198.

[2] F. S. Diba, H. J. Lee. J.
Electroanal.
Chem.
769, (2016) 5.

[3] H. R. Kim, C. M. Pererira, H. Y. Han, H. J. Lee. Anal. Chem.
87, (2015) 5356.
Preparation of Pt@Cu Core-Shell Particles Incorporated in Poly-(3,4-ethylenedioxythiophene) for Catalytic Applications
Authors: Peipmann Ralf , Endrikat Anna , Bund Andreas
Published: February 2020

Hybrid materials offer the possibility to combine advantageous properties of the individual components. In the macroscopic world adobe or reinforced concrete are well known examples. The same principle can also be applied to electrodes for electro-catalytic reactions. The usually precious metal catalyst like Pt for fuel cells (or Au for sensors) is reduced in size (and thus in costs) to smaller and smaller particles which are bonded to supporting surfaces.

An interesting approach is to prepare a porous matrix in which these catalytic particles can be homogeneously incorporated. Promising candidates are conducting polymers like poly-(3,4-ethylenedioxythiophene) (PEDOT) whose structure can be tuned by the used electrolyte and/or the supporting electrolyte.

To homogeneously incorporate the particles they should be prepared in situ with the polymer which is possible by cyclic voltammetry or (reversed) pulse methods. As Pt2+ has the possibility to oxidize EDOT directly we deposited Cu as an intermediate with the polymer by cyclic voltammetry. In a second step a chemical exchange reaction was performed using a Pt4+containing solution. This approach can yield Pt@Cu core shell particles embedded in a polymer matrix. A positive effect of this is also that the electronic structure of the Pt layer is modified by the underlying Cu core which can lead to enhanced catalytic activities.

The cyclic voltammograms of the preparation of PEDOT/Cu films show a superposition of PEDOT and Cu features. At potentials more positive than ca. 0.9 V vs. Ag/AgCl sat. KCl polymerization of EDOT occurs while at more negative potentials the capacitive behaviour of the PEDOT film dominates next to the Cu redox waves at ca. 50 mV. SEM/EDX analyses showed that thus prepared films contain 10 to 17 wt% Cu depending on the switch-off potential. If the preparation stopped before Cu oxidation Cu crystallites could be observed on the PEDOT surface and the Cu content was higher. In the case of well oxidized films no distinct Cu centres could be found (see figure 1).

The chemical exchange reaction with Pt was monitored by a quartz crystal microbalance (QCM). According to QCM data the deposited mass of Pt corresponds to ca. 60 monolayers on the geometric area.

This contribution will discuss the preparation of the PEDOT/Pt@Cu hybrid films as well as the electrochemical and mechanical characterization of these films. This will include CV and impedance (EIS) data as well as QCM data.

Fig. 1. SEM images of a PEDOT/Cu film with the preparation stopped at potentials negative to the Cu redox potential.

(left) top view of the surface and (right) FIB cross section.

Figure 1
New Software for Simulation of Electrochemical Reaction Mechanisms of Any Complexity
Authors: Svir Irina , Klymenko Oleksiy , Oleinick Alexander , Amatore Christian Andre
Published: February 2020

We introduce here our scientific software KISSA designed for automatic simulation of electrochemical reaction mechanisms of any complexity, including those leading to ECL emission at planar, (hemi)spherical and (hemi)cylindrical working electrodes (KISSA-1D) as well as at microelectrodes such as disk or band (KISSA-2D).

Simulations are performed by KISSA using a novel approach [1, 2] developed by the authors which involves conformal coordinate transformations to overcome the numerical difficulties arising from diffusional propagation of species and automatic grid adaptation based on the detection of large kinetic terms to obtain accurate results for both concentrations and electrochemical currents even in the presence of steep concentration gradients. This approach allows for efficient resolution of all physicochemical and mathematical issues connected both with edge effects (nano- and microelectrodes) and considerable disparity of time and length scales of the underlying processes arising due to quickly changing electrode potential and/or extremely rapid homogeneous chemical reactions for any complex mechanisms.

The software offers a possibility to take into account spontaneous natural convection which limits the extent of the diffusion layer and leads to the establishment of a steady state current even at macroelectrodes. Furthermore, this enables setting correct and thermodynamically consistent initial conditions within the stagnant layer when the system is pre-equilibrated at a given rest potential for a finite period of time [3]. The software also allows simulating complex adsorption dynamics, i.e., kinetics and chemical reactions involving surface-bound species [4, 5].

The programs offer convenient entry of a reaction mechanism and parameters and provide access to the computed dynamic spatial distributions of all important quantities such as currents and current densities, concentration distributions of all reactants, surface coverage of adsorbed species [4, 5] as well as ECL intensity [6] (if applicable) through a graphical user interface [7].

[1] C. Amatore, O.V. Klymenko, I. Svir, Electrochem. Commun. 12 (2010) 1170.

[2] O.V. Klymenko, I. Svir, A. Oleinick, C. Amatore, ChemPhysChem 13 (2012) 845.

[3] C. Amatore, O.V. Klymenko, I. Svir, Anal. Chem. 84 (2012) 2792.

[4] O.V. Klymenko, I. Svir, C. Amatore, J. Electroanal. Chem. 688 (2013) 320.

[5] O.V. Klymenko, I. Svir, C. Amatore, Molecular Physics, 112 (2014) 1273.

[6] O.V. Klymenko, I. Svir, C. Amatore, ChemPhysChem, 14 (2013) 2237.

[7] http://kissagroup.com/index.php/bibliography
In-Situ Electrochemical Microscopy Techniques (AFM-SECM, sMIM and Liquid SEM) to Study Solid/Liquid Interface
Authors: Velmurugan Jeyavel , Agarwal Amit , An Sangmin , Choudhary Eric , Stevanovic Ana , Yi Feng , LaVan David , Tselev Alexander , Ievlev Anton , Kalinin Sergei V. , Kolmakov Andrei , Szalai Veronika
Published: February 2020

Ever since the invention of the scanning probe and electron microscope, a goal has been to image liquid specimens as easily as in a light microscope, and to measure liquid processes with a good resolution in both spatial and temporal. Direct observation of electrochemical processes is essential to develop electrochemical models, optimize nanostructures, and understand reaction mechanisms. We have developed and improved some in-situtechniques and tested them on electrochemical processes.

In an attempt to have improved topography and surface reactivity information, we have designed and fabricated nanometer sized scanning probe tips for combined atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM). We report here the characterization of these tips using an in-house fabricated calibration sample and a model anode. In another approach we have used scanning near-field microwave microscopy (sMIM) for imaging in liquids using ultrathin molecular impermeable membranes separating scanning probes from samples enclosed in environmental cells. We imaged a process of dendritic growth during model electroplating reaction. Due to very small energy of few gigahertz microwaves we demonstrate the advantages of this microscopy for non-destructive artifact-free imaging compared to electron microscopy [1]. Different to TEM in liquids which has been used successfully to study the electrochemical processes very little research has been performed using liquid SEM [2]. We explore this imaging modality and describe here a novel chip [3,4] and cell designs enabling us to study Ag electrodeposition in real time using SEM in liquids. All these techniques are complementary and well suited for in situelectrochemistry. These examples demonstrate the versatility of these techniques and can be extended to other applications such as corrosion, battery and bio-medical research.

References:

[1] A. Tselev, J. Velmurugan, A. Ievlev, S. Kalinin,and A. Kolmakov ACS Nano, 10 (3),3562, 2016

[2] E. Jensen, C. Kobler, P. S. Jensen and K. Molhave, Ultramicroscopy, 129, 63, 2013

[3] F. Yi, W. Osborn, J. Betz, J and D.A. LaVan Microelectromechanical Systems, 24, 1185, 2015

[4] M. D. Grapes, T. LaGrange, L.H. Friedman, B. W. Reed, G. H. Campbell, T. P. Weihs and D. A. LaVan Review of Scientific Instruments, 85, 084902, 2014
Nanocrystal Seeded Growth of High Activity Ni-Mo Electrocatalysts for the Hydrogen Evolution Reaction
Authors: McKay Ian Salmon , Schwalbe Jay , Cargnello Matteo , Majumdar Arun
Published: February 2020

Nickel-molybdenum-based materials are widely used functional oxide electrocatalysts for the hydrogen evolution reaction. While molybdenum co-deposits improve the activity of bare Ni, the origin of the synergetic mechanism between Ni and Mo remains poorly understood, largely because of the ill-defined nature of systems employed for interpreting this effect. In this work, we directly investigate the interaction between Ni and Mo phases by depositing size-controlled Ni nanocrystals onto Ti and Mo substrates, and subjecting the synthesized materials to electrocatalytic conditions with and without dissolved molybdenum species.Thanks to the uniformity of the active phases employed in this work, we are able to disentangle the competing effects of a bulk electronic interaction between Ni and Mo, and a separate enhancement mechanism centered on the formation of a Mo-rich alloy phase. Potentiostatic and impedance techniques shed light on the electrochemical activity of the NiMo surfaces, while Auger spectroscopy and in-situ TEM are used to elucidate the nature of the samples and the changes that occur during electrochemical testing. Finally, the information gained is used to design a Ni-nanocrystal seeded Mo deposition procedure that yields an electrocatalytic surface with a hydrogen evolution onset overpotential of <0.15V at pH 14. This work not only provides crucial information for improving the activity of current Ni-Mo systems, but also a general paradigm for investigating fundamental interactions and synergic effects in electrocatalytic materials.
Discovering Pd-B/C As a Potential Bifunctional Catalyst in the Formic Acid ↔ Carbon Dioxide Conversion Cycle
Authors: Jiang Bei , Jiang Kun , Cai Wen-Bin
Published: February 2020

It is well known that facile interconversion of HCOOH and CO2 is very important in hydrogen production, direct formic acid fuel cell, as well as neutral emission of CO2. In the past few years, we have investigated chemical and electrochemical dehydrogenation of formic acid over Pd-B/C and Pd/C, revealing that significantly enhanced dehydrogenation of HCOOH can be achieved on the home-synthesized Pd-B/C[1-3]. B-doping in the Pd lattice can be attained during the reduction of a Pd(II) precusor from an aqueous solution using dimethylamine borane as the reducing agent and boron source[1]. The XRD result suggested the expansion of Pd lattice and the XPS result indicated the partial electron transfer from B to Pd [3], lowering down the d-band center of Pd, favoring the dehydrogenation pathway, as supported by latest DFT calculation by Studt and Norskov[4]. In situ ATR-IR spectroscopy on Pd-B/C and Pd/C was comparatively conducted in conditions mimicking hydrogen production or direct formic acid fuel cell, it is revealed that desired dehyrogenation pathway forming CO2 is enhanced accompanied with inhibited accumulation of CO poissoning specie on Pd-B/C [2-3]. Since both forward and backward conversions may involve the weakly adsorbed formate as an active intermediate, it is thus interesting to explore the use of Pd-B/C as the catalyst for electroreducing CO2 to form HCOOH. Indeed, our recent preliminary analysis on the products of CO2 electroreduction over Pd-B/C and Pd/C catalysts in a KHCO3 electrolyte indicates that the formation of HCOOH on Pd-B/C is greatly enhanced as compared to that on Pd/C.

Acknowledgements
：Financial supports from NSFC (grant No. 21273046 and 21473039）and the 973 Program (No. 2015CB932303) of MOST are highly appreciated

References
：

[1] J.Y. Wang, Y.Y. Kang, H. Yang, and W.B. Cai,  J. Phys. Chem. C
,
113, 8366 (2009).

[2] K. Jiang, K. Xu, S.Z. Zou, and W.B. Cai, J. Am. Chem. Soc., 136, 4861 (2014).

[3] K. Jiang, J.F. Chang, H. Wang, S. Brimaud, W. Xing, R. J. Behm, and W.B. Cai , ACS Appl. Mater. Interfaces, 8, 7133(2016)

[4] J. S.Yoo, Z.-J. Zhao, J. K. Nørskov, and F. Studt, ACS Catal., 5, 6579 (2015).
Insights from Near-Surface Atomic Structures and Composition for Catalytic Activity and Stability of Oxides in Electrochemical Reactions
Authors: Feng Zhenxing , Shao-Horn Yang
Published: February 2020

Electrocatalysts play an important role in catalyzing the kinetics for many reactions (e.g., oxygen reduction reaction, oxygen evolution reaction and CO2photoelectrochemical reduction) for many energy storage and conversion devices, such as metal-air batteries, electrolyzer and fuel cells. Although oxides are promising catalysts due to their natural abundance, low cost, and widely tunable properties, the design of oxide electrocatalytic functionality is not straightforward due to the lack of information on the oxide surface atomic structure and chemistry.

Using a combination of in situ surface-sensitive X-ray diffraction and spectroscopy methods, we have studied several electrochemical devices (e.g., (La0.5Sr0.5)2CoO4+δ/La1-x
Sr
x
CoO3-δ/GDC/YSZ heterostrucured cathodes for solid oxide fuel cells, spinel oxides for supercapacitors, LiMn2O4 for batteries) and model systems (e.g., La1-x
Sr
x
CoO3-δ/SrTiO3 for fuel cells and MgMn2O4 thin film for battery cathodes) to obtain their near-surface atomic structures and composition changes during various electrochemical reactions. The information we learned provides critical insights about the dynamic changes of oxides during the electrochemical reactions and their influences on alternating reaction paths for optimizing ORR/OER and CO2 reductions. Based on these findings, we have figured out strategies to control the oxide surfaces for the enhanced activity and better stability for fuel production, energy storage, and CO2 reduction.

References:

(1) Z. Feng, W. T. Hong, D. D. Fong, Y.-L. Lee, Y. Yacoby, D. Morgan, and Y. Shao-Horn, Accounts of Chemical Research, accepted, 2016

 (2) K. A. Stoerzinger, W.T. Hong, E.J. Crumlin, H. Bluhm, and Y. Shao-Horn, Accounts of Chemical Research, 48, 2016, 2976-2983.

(3) Z. Feng, X. Chen, L. Qiao, A.L. Lipson, T.T. Fister, L. Zeng, C. Kim, T. Yi, N. Sa, D.L. Proffit, A.K. Burrell, J. Cabana, B.J. Ingram, M.D. Biegalski, M.J. Bedzyk, P. Fenter, ACS Applied Materials & Interfaces, 7, 2015, 28438-28443.
(Invited) Ionic Liquids in Separations and Mass Spectrometry
Authors: Armstrong Daniel
Published: February 2020

Room-temperature ionic liquids (RTILs), are a class of nonmolecular ionic solvents with low melting points. Most common RTILs are composed of unsymmetrically substituted nitrogen-containing cations (e.g., imidazolium, pyrrolidinium, pyridinium) or phosphonium cations with inorganic anions (e.g., Clˉ, PF6ˉ, BF4ˉ). Most of these more common ILs are of limited use analytically. Consequently many ILs containing a variety of cations and anions of different sizes have been synthesized to provide specific characteristics. In this presentation an overview of the structure and properties of ILs and a description of their expanding use in various applications in separations, chromatography and mass spectrometry will be given. A number of studies have appeared indicating that ILs have exceptional promise as stationary phases. They have a dual nature selectivity in that they separate nonpolar molecules as would a nonpolar stationary phase and they separate polar molecules as would a polar stationary phase. Many ILs have exceptional thermal stability. They are being used increasingly in a variety of applications including 2-D GC, enantiomeric separations, the measurement of water in samples/solvents/materials and compact field GC units. ILs have proven to be the best liquid MALDI-MS matrix since we introduced them as such a few years ago. The properties of ILs that make them effective will be discussed. Further, the dications developed for high stability ILs have found another novel use in electrospray ionization (ESI) MS as a reagent for ultra sensitive anion analysis. These will be discussed as well.
Ionic Liquids and Organic Ionic Plastic Crystals Based on Tris(fluorosulfonyl)methide
Authors: Matsumoto Hajime , Mizukado Junji , Wan Peng-cheng
Published: February 2020

Ionic liquids (ILs) composed of low coordinating anions such as perfluoroanions have been studied as a unique electrolyte for a lithium battery for past two decades.[1] The best performance of a lithium battery system using only ILs was achieved by bis(fluorosulfonyl)amide (FSI-, FSA- or f2N-) [2]. The existence of FSO2- group in f2N-
 might cause such a good performance. In this study, we tried to prepare new perfluoromethide, tris(fluorosulfonyl)methide (f3C-) to investigate the effect of FSO2
- group on physicochemical and electrochemical properties of onium salts composed of f3C-. The physical, thermal and electrochemical properties of the ILs were compared to another similar methide anion (tris(trifluoromethylsulfonyl)methide, Tf3C-). The Tf3C- could form ILs with conventional cations such as N-ethyl-N-methylimidazolium (C1C2im+) and N,N-dimethyl-N-methyl-N-(2-ethoxymethyl)ammonium (N2,2,1,2O1
+), however, It was quite interesting that the f3C- had a tendency to form organic ionic plastic crystals (OIPCs) rather than ILs. As far as we know, the N2,2,1,2O1
+ forms ILs with various anions even PF6
-
 [3] however, the f3C- forms good OIPCs with N2,2,1,2O1
+ (T
m
= 69 °C, T
s-s = -29 °C).

 The cathodic limiting potential of a ILs composed of N-ethyl-N-methylimidazolium (C1C2im+) and f3C- was about 1.0 V shifted toward negative potential with adding Lif3C and stable lithium deposition and redissolution cycle could be successfully observed. The apparent charge transfer resistance at an interface between a Li metal and [C1C2im][f3C] was more stable over 18 months than that for [C1C2im][Tf3C], which indicated that the existence of FSO2- group in a perfluoroanion must be importance to maintain a stable SEI on the lithium metal as previously reported in a bis(fluorosulfonyl)amide based melts.[3] Furthermore, the apparent charge transfer resistance at a charged LiCoO2 composite electrode (4.2 V vs Li/Li+) in the [C1C2im][f3C] was almost the same value during over 500 charge and discharge cycles, which suggested that the good electrochemical stability not only for a lithium metal but also for the charged cathode were achieved with using the new methide f3C- composed of FSO2
- group as in bis(fluorosulfonyl)amide based melts. These results suggest that the FSO2
- group have an essential moiety to design an novel perfluoroanions for a lithium battery electrolyte. The f3C-provided not only ILs as a novel lithium battery electrolyte but also OIPCs and the molecular design rules, which have not yet been clearly understood.

Acknowledgment

This study was financially supported by JST, ALCA-SPRING project.

References

[1] H. Matsumoio. in Electrolytes for Lithium-ion Batteries, T. R. Jow, K. Xu., O. Borodin and M. Ue, Eds., Springer. 2014, ch. 4, and references therein.

[2] H. Matsumoto, H. Sakaebe, K. Tatsumi, M. Kikuta, E. Ishiko, M. Kono, J. Power Sources, 160(2), (2006) 1308.

[3] H. Matsumoto, H. Sakaebe, K. Tatsumi, ECS Transactions,16(35), (2009)59.

Figure 1
Fluorination Behavior of Uranium-Zirconium Mixture by Hydrogen Fluoride
Authors: Ono Takahiro , Sato Nobuaki , Nezu Atsushi , Uchiyama Takafumi , Matsuura Haruaki
Published: February 2020

Due to the accident of Fukushima Daiichi nuclear power plant, fuel debris has been produced inside the nuclear reactor vessels. It would be very difficult to reprocess such fuel debris by using normal procedures, since the fuel debris may contain surrounding structural material. To reprocess fuel debris, a pyroprocess of selective fluorination and a molten salt electrolysis have been proposed. The advantage of pyroprocess is to decrease the volume of radioactive wastes and on-site treatment. The proposed method consists on a selective fluorination, a selective dissolution, and a molten salt electrolysis. The aim of this study is to investigate the fluorination behavior of uranium – zirconium oxide mixture.

All experiments was performed at Institute of Multidisciplinary Research for Advanced Materials, Tohoku University. The samples of uranium – zirconium mixtures have been prepared as follows. First, UO2 was made by the reduction using Ar – H2 mixture gas for U3O8 at 1000oC. Second, UO2 and ZrO2 were mixed by the molar ratios of 1:9, 3:7, 5:5, 7:3 and 9:1. Finally, these samples were treated in the environment of either oxidation or reduction. To evaluate fluorination behavior of these mixtures, a thermogravimetric differential thermal analyzer and a powder X-ray diffractometer. Each sample was set in a platinum pan inside the chamber of TG-DTA and hydrogen fluoride gas in 60 ml/min was introduced in it. In the TG-DTA, temperature raising rate was 5oC/min or 10oC/min until 500oC. Finally, the samples used for the TG-DTA were characterized by the XRD.

In the zirconium rich mixtures, rapid fluorination reaction occurs at relatively higher temperature (400oC), while in the uranium rich mixtures, slow fluorination reaction occurs at relatively lower temperature. Depending on pre-treated environment of the mixtures, the difference of fluorination behavior is identified. In general, relatively slower fluorination reaction occurs in the mixtures pre-treated in oxidation environment, while rapid fluorination occurs in the mixtures pre-treated in reduction environment. These facts would be caused by either degree of amount of solid solution in the mixtures or morphology of samples. How much degree of fluorination is the best to introduce into molten salt is going to under consideration.

This work was supported by Network Joint Research Center for Materials and Devices, 2015223 and JSPS Kakenhi 15K0665.
Intermediate-Temperature Operation of Sodium Secondary Batteries with High Rate Capability and Cyclability Using Ionic Liquid Electrolyte
Authors: Matsumoto Kazuhiko , Chen Chih-Yao , Kiko Tomohiro , Hwang Jinkwang , Hosokawa Takafumi , Nohira Toshiyuki , Hagiwara Rika
Published: February 2020

Ionic liquid electrolytes are widely studied to construct safe electrochemical devices owing to their unique properties such as low volatility, low flammability, and wide liquid-phase temperature range.

Ionic liquids based on sulfonylamide anions (bis(fluorosulfonyl)amide anion (FSA-) have low melting point, low viscosity, and high ionic conductivitysome and are attractive as electrolytes in secondary batteries. The present study reports physical and electrochemical properties of FSA-based ionic liquid electrolytes for secondary betteries operating from room temperature to intermediate temperature. Intermediate operation of secondary batteries in is available in some circumstances such as an engine compartment of automobiles and is preferable to enhance both the ion transport and electrode reactions.

The Na[FSA]-[C3C1pyrr][FSA] (C3C1pyrr+ = N-methyl-N-propylpyrrolidinium) and Na[FSA]-[C2C1im][FSA] (C2C1im+ = 1-ethyl-3-methylimidazolium) ionic liquid systems have wide liquid phase temperature ranges around room temperature and high ionic conductivities [1,2].

Immersion of Na metal in FSA- and TFSA-based ionic liquids clearly showed that FSA-based ionic liquids form stable film on Na metal to prevent futher reduction. Dendrite formation during Na metal electrodeposition is suppressed by increasing temperature. Excellent rate capability and cycle property were observed for the Na2FeP2O7 positive electrode in FSA-based ionic liquids at 363 K.[3] The origin of this performance will be discussed based on transport properties of Na+ by considering transport number and Na+fraction in these ionic liquids.

Acknowledgements:

This study was partly supported by Advanced Low Carbon Technology Research and Development Program (ALCA) of Japan Science and Technology Agency (JST) and Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) program “Elements Strategy Initiataive to Form Core Research Center”.

References

[1] K. Matsumoto, T. Hosokawa, T. Nohira, R. Hagiwara, A. Fukunaga, K. Numata, E. Itani, S. Sakai, K. Nitta, S. Inazawa, J. Power Sources, 2014, 265, 36-39

[2] K. Matsumoto, Y. Okamoto, T. Nohira, R. Hagiwara, J. Phys. Chem. C, 2015, 119, 7648-7655.

[3] C. Chen, K. Matsumoto, T. Nohira, C. Ding, T. Yamamoto, R. Hagiwara, Electrochim. Acta, 2014, 133, 583-588.
"Click Synthesis" of Mercaptosilyl-Functionalized Ionic Liquids via Thiol-Ene Chemistry for Use as Hydrophobic Surface Coating Agents
Authors: Sanchez Zayas Manuel , Nestor Stephen , Gaitor Jamie , Reardon Melissa , Mirjafari Arsalan
Published: February 2020

The thiol-ene “click” transformation described here is a high-yielding and simple fusion process, leading to a series of hydrophobic, multifunctionalized ionic liquids containing long thioether spacers (C7−C15) with low melting points and high thermal stability. The process exhibits broad scope and provides a series of imidazolium, ammonium and phosphonium-based mercaptosilyl-functionalized ionic liquids (16 examples) in excellent yields and exclusive anti-Markovnikov regioselectivity. In order to aid in defining their practical range of use in various applications, the thermophysical properties of the new ionic liquids such as glass transition temperature, decomposition temperature, viscosity and density along with their water contents, were studied. The mercaptosilane class of ILs can have important applications due to their hydrophobicity, moderately low viscosities, high thermal stabilities and wide liquids range. The synthesized ionic liquids were found to be active surface coating agents and were successfully immobilized on magnetite supermagnetic Fe3O4 nanoparticles.  The representative ionic liquids with different side chains were immobilized on the surface of Fe3O4 supermagnetic nanoparticles and showed high organic loading (27.40−39.81 wt%) and low size of nanoparticles (6.72−10.12 nm). The ability to introduce trimethoxysilane into the structures of ionic liquids would open new horizons for their applications such as surface modification and hybrid materials. The incorporation of a thiol group to the structure of silane-functionalized ionic liquids could be utilized to construct novel organic-inorganic materials due to strong affinity of thiols to specific metallic surfaces.
Electrochemical Synthesis of Nanomaterials in Molten Salts
Authors: Kuznetsov Sergey A.
Published: February 2020

For the first time by electrochemical synthesis from NaCl-KCl-NaF-GdF3-KBF4 melt at temperature 1023 K and with utilization of molybdenum cathode the gadolinium hexaboride nanotubes were synthesized. Most likely GdB6 nanotubes formation is ruled by intercalation mechanism. Gadolinium hexaboride lattice is the framework of boron atom octahedrons, in gaps of which the gadolinium atoms are situated. These gaps are spacious enough to host the metal atoms without deformation and even with reserve of vacant space. Electrochemical synthesis of GdB6 occurs at potentials negative enough for alkali metal cations electroreduction. So alkali metal cations intercalate into the emptiness of hexaboride lattice where cations are reduce in situ. The metal atoms have larger radius than its cations so they provoke mechanical strain. At the certain value of the strain GdB6 splits with nanotubes formation.

Nanoneedles of TaO with tetragonal crystal lattice were obtained by electrolysis of CsCl melt, containing monooxofluoride complexes of tantalum. It was determined the correlation between the redox potential of molten system, temperature and stability of tantalum monoxide.

Multi-layered tantalum boride structures were produced via electrolysis in the NaCl-KCl-NaF-K2TaF7-KBF4 melt. The overall thickness of the layers, synthesized under direct current regime, was 30-50 μm, and they consisted of numerous fine layers (nanolayers).

A new generation of highly active and stable catalytic nanostructured coatings for the water-gas shift reaction by high temperature electrochemical synthesis in molten salts has been developed. The steady-state reaction rates for the Mo2C/Mo coatings were higher than those for the bulk Mo2C and commercial Cu/ZnO/Al2O3 catalysts over in the temperature range explored. The catalytic activity is enhanced by at three orders of magnitude comparing to that of the pure Mo2C phase. The methanation reaction was completely suppressed in the whole temperature range studied on the Mo2C/Mo systems. The catalytic activity remained constant during 5000 hours on-stream. The coatings were also stable during the thermal cycling, while the activity of commercial catalysts tends to decrease with time. A novel microstructured reactor/heat-exchanger containing eight sections with a cross-section of 10 mm x 10 mm and a length of 100 mm has been designed and constructed. Each section of the reactor contains flat, perforated Mo plates and Mo wires with a diameter of 250 mm and a length of 100 mm coated with a porous Mo2C layer.

Nanoneedles of silicon were obtained in chloride-fluoride melts containing K2SiF6 by potentiostatic electrolysis which accompanied by reaction of disproportionation.
Electrolytic Production of Aluminium Using Gas Anode Supplied with Methane
Authors: Khalaghi Babak , Haarberg Geir Martin , Kjos Ole Sigmund , Gudbrandsen Henrik , Osen Karen Sende , Mokkelbost Tommy
Published: February 2020

Mitigation of carbon emissions from the aluminium electrolysis cell is one of the main research topics of the aluminium industry. Prolonged research on inert anode candidates has not led to a commercial product yet. Another approach is to apply a reducing gas, e.g. methane, to the bath through porous anodes; where it reacts with oxygen-containing ions of the bath. When the gas (methane) replaces the consumable anode in reacting with the bath, the amount of generated CO2is reduced substantially. However, if the porous anode is made of carbon, the anode itself also takes part in the anodic reaction to some extent. Therefore, the consumption of the reducing gas and the anode occur simultaneously.

Aluminium electrolysis experiments were carried out using porous graphite electrodes supplied with methane. The potential and weight changes of the anode together with the off gas analyses were done to study the effect of methane supply. It was found that the supply of methane during electrolysis led to decreased consumption of the graphite anode. But at the same time, the level of HF in the off gas showed a noticeable rise, which was expected due to the formation of water from methane oxidation. Provided that the share of the methane in the anodic reaction increases, the anode will be consumed less and a smaller amount of CO2is generated. Different grades of graphite were tested. Moreover, experimental parameters such as current density and anode gas composition were varied.

Figure below: Anode potential plotted against time during aluminium electrolysis for two experiments where in one (top) only N2 and in the other (below) N2 + CH4 were flushed through the porous anodes. The anode was made of isotropic graphite. i = 0.4 A.cm-2, T = 970°C. The values in the figure are flow of the gas in ml.min-1.

Figure 1
Rest Potentials of Binary Mixtures of Ionic Liquids and Threshold Voltages of Electric-Double-Layer Transistors
Authors: Nanjo Chihiro , M. Matsushita Michio , Awaga Kunio
Published: February 2020

There is a growing attention to the electric-double-layer (EDL) transistors, in which electrolytes are adopted as gate dielectrics, because a strong electric field produced by EDLs improves transistor performance. In our previous study, we investigated the relation between the rest potentials and the threshold voltages of EDL transistors, using two kinds ambipolar phthalocyanines and various ionic liquids. It was found that the rest potential is a unique property of ionic liquid, and the threshold voltages of the EDL transistors are proportional to the rest potentials of the ionic liquids. This means that the threshold voltages of the EDL transistors can be tuned by controlling the rest potentials, though what determines the rest potentials of the ionic liquids is still unclear.

In the present study, we tried to understand the rest potentials of the ionic liquids and to control the threshold voltages of the EDL transistors, by making the binary mixtures of ionic liquids, because their mixing ratios can be continuously changed. We prepared the binary mixtures of the ionic liquids, combining DEME-TFSI and five kinds of ionic liquids, shown in the inset of Figs. 1 and 2. These combinations were selected, because these ionic liquids are miscible each other and the rest potential of DEME-TFSI is higher than those of the others.

The rest potentials of the binary ionic liquids were examined with an Ag/AgCl reference electrode and a Pt working electrode. The rest potentials of the binary ionic liquids were found to change non-linearly with respect to the mixing ratio of the ionic liquids (Fig. 1). This dependence can be well fit to the equation of y = a + b*log(x), where x is the mixing ratio and, a and b are the fitting parameters. This strongly suggests that the rest potential of ionic liquid is governed by its chemical potential μ, because this equation has the same form as that of the chemical potential, μ = μ
0 + RTln(x), where R is the gas constant. Then, we tested the EDL transistors of platinum phthalocyanine (PtPc) which showed a high stability even in various ionic liquids. It was found that there was a linear relation between the rest potentials and the threshold voltages of the EDL transistors (Fig. 2), and the threshold voltages can be continuously controlled by changing the mixing ratio of the ionic liquids.

Figure 1
Electrochemical Behavior of Tris(2,2'-bipyridine)Cobalt Complex in Some Ionic Liquids
Authors: Katayama Yasushi , Nakayama Shota , Tachikawa Naoki , Yoshii Kazuki
Published: February 2020

Electrostatic interaction between a charged species and the ions composing ionic liquids is considered much stronger than that in conventional electrolyte solutions. Strong electrostatic interaction is expected to influence electrochemical reactions of the charged species. We have already reported the diffusion and charge transfer of tris(2,2'-bipyridine) and tris(1,10-phenanthroline) complexes of some transition metals are affected by the charge densities of redox species and the ions composing ionic liquids[1-6]. In the present study, the electrochemical behavior of tris(2,2'-bipyridine)cobalt complex ( [Co(bpy)3]3+ and [Co(bpy)3]2+) was investigated in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) and 1-ethyl-3-methylimidazolioum tetrafluoroborate (EMIBF4).

BMPBr was prepared by the reaction of methylpyrrolidine and butyl bromide, purified by recrystallization and dried under vacuum. BMPTFSA was prepared by the metathesis of BMPBr and LiTFSA. EMIBF4 was purchased from Kanto Chemical. [Co(bpy)3](TFSA)2 was prepared by addition of LiTFSA into CoCl2 and bpy aqueous solution. [Co(bpy)3](TFSA)3 was prepared by oxidation of [Co(bpy)3]2+ with H2O2 under acidic condition and addition of LiTFSA. [Co(bpy)3](BF4)2 and [Co(bpy)3](BF4)2 were prepared in the same way using NaBF4 instead of LiTFSA. Electrochemical measurements were performed with an air-tight three electrode cell assembled in a glovebox of dry Ar atmosphere. Platinum was used as a working and counter electrode. Silver immersed in BMPTFSA containing 0.1 M AgCF3SO3was used as a reference electrode.

The diffusion coefficients of [Co(bpy)3]3+ and [Co(bpy)3]2+ were determined by chronoamperometry at various temperatures. The diffusion coefficients of [Co(bpy)3]3+ and [Co(bpy)3]2+ were close to those of [M(bpy)3]3+ and [M(bpy)3]2+ (M = Fe and Ru) in each ionic liquid, verifying the diffusion of the charged species is related to the size and charge density of the diffusing species. The charge transfer rate of [Co(bpy)3]3+/2+ was slower than those of [M(bpy)3]3+/2+ (M = Fe and Ru), probably due to the difference in the electron configurations. Furthermore, the apparent reaction entropy change of [Co(bpy)3]3+/2+ was larger than those of [M(bpy)3]3+/2+ (M = Fe and Ru), suggesting the large contribution of the difference in the electron configurations of [Co(bpy)3]3+ and [Co(bpy)3]2+to the apparent reaction entropy change.

References

[1] Y. Katayama, M. Yoshihara, and T. Miura, J. Electrochem. Soc., 162, H501 (2015).

[2] Y Katayama, Y. Toshimitsu, and T. Miura, Electrochim. Acta, 131, 36 (2014).

[3] Y. Yamato, Y. Katayama, and T. Miura, J. Electrochem. Soc., 160, H309 (2013).

[4] Y. Katayama, Y. Toshimitsu, and T. Miura, J. Electrochem. Soc., 160, H219 (2013).

[5] Y. Toshimitsu, Y. Katayama, and T. Miura, Electrochim. Acta, 82, 43 (2012).

[6] N. Tachikawa, Y. Katayama, and T. Miura, J. Electrochem. Soc., 154, F211 (2007).