bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the Growth of Pt Nanoparticles by Galvanic Displacement on ITO Nanocubes for ORR
Authors: Liu Ying , Zhao Shuai , Mustain William E
Published: February 2020

Though proton exchange membrane fuel cells (PEMFCs) are at the cusp of widespread commercialization, there are several issues that must be addressed to improve their long-term reliability. One considerable improvement to existing PEMFC systems would be in incorporation of higher stability electrocatalysts, while concomitantly improving activity to reduce loading and cost, at the oxygen reduction cathode.

Recent work in our group has focused on investigating the intrinsic stability of Sn-doped indium oxide [1] as well as its activity and stability in the ORR environment [2]. This work has even included the investigation of the influence of Pt loading on ITO and its effect on the oxygen reduction activity and Pt/ITO stability [3]. One of the more interesting findings for Pt/ITO prepared by galvanic displacement is that low Pt loadings yield a single type of particle with preferential {111} faceting, which gives yields its characteristic high activity. However, at higher loading secondary particles with a completely different structure emerge. One of the most interesting open questions is how these two particle types influence the activity and stability of the Pt/ITO.

In this work, we present a statistical model that utilizes a modified Poisson probability distribution function to understand how the primary and secondary Pt nanoparticles grow during the galvanic displacement. The statistical model is also used to predict the specific and mass activity of the Pt/ITO as a function of Pt loading. The model prediction and experimental results for the specific activity are shown in Figure 1. Excellent agreement was observed between the theoretical prediction and the experimental data. Also, an interesting oscillatory behavior was predicted, which also appears corroborated by the experimental data. The behavior is caused by the counterbalancing of the high activity of the preferentially faceted Pt/ITO nanoparticles and the secondary particles that show and activity similar to Pt supported on carbon. The number of {111} also clearly plays a role [4], which is built into the model.

This talk will focus on the model development, calculation of model parameters, and linking critical elements of the model to the activity and stability of Pt/ITO electrocatalysts for the oxygen reduction reaction.

References.

Y. Liu and W.E. Mustain, “High stability, high activity Pt/ITO oxygen reduction electrocatalysts”, J. Am. Chem. Soc., 135 (2013) 530

Y. Liu and W.E. Mustain, “Stability limitations for Pt/Sn–In2O3 and Pt/In–SnO2 in acidic electrochemical systems”, Electrochimica Acta, 115 (2014) 116-125

Y. Liu and W.E. Mustain, “High Stability, High Activity Pt/ITO Oxygen Reduction Electrocatalysts”. Abstract 86, 223rd Meeting of the Electrochemical Society, San Francisco, CA.

M. Shao, A. Peles and K. Shoemaker, Nano Letters, 11 (2011) 3714.
Invited: Development of Nstf Electrode for PEMFC
Authors: Kongkanand Anusorn , Sinha Puneet , Liu Zhongyi , Thompson Eric , Zhang Jingxin , Kukreja Ratandeep , Moylan Thomas , Clancey Joel W. , Cavanagh Andrew S. , George Steven M.
Published: February 2020

Ionomer-free ultrathin electrodes, such as the 3M Nanostructured Thin Film (NSTF) electrode, provide a plausible pathway to reduce Pt cost and enhance the electrode durability in low temperature fuel cells. However, the absence of ionomer, the small electrode thickness, and the small Pt area make operating a fuel cell a challenge.

We have developed several materials and system solutions to mitigate these issues1,2 and numeric models3,4 to enhance our understanding of fuel cell performance in NSTF electrodes. We then further investigated the stability of the NSTF electrodes under accelerated tests5 and tests that were designed to simulate real-life automotive operation6. We observed irreversible voltage decay behavior that could not be explained by known electrode degradation mechanisms of carbon corrosion, Pt dissolution, or membrane thinning. Correlation among different events that contribute to the degradation will be discussed. For example, we found that it is important to avoid entering a potential window in which irreversible degradation occurs. Mitigation strategies to maximize the electrode life will be suggested.

Lastly, we will present our recent development in using atomic layer deposition to form a uniform thin layer of Pt on an NSTF support. This method can reduce the Pt loading by a factor of three compared to the current method. Its fuel cell activity will be also discussed.

Acknowledgements

The authors thank Mark K. Debe, Edward M. Fischer, and Andrew Steinbach of 3M for providing NSTF MEAs and for useful discussions. Thanks are also extended to Frank Coms, Wenbin Gu, Yeh-hung Lai for insightful comments; Ted Gacek, Heidi Viterise, Tom Jackson, Matt Dioguardi, Jeanette Owejan, Scott Moose, Travis Downs, and Rob Moses for engineering support.

References

A. Kongkanand, M. Dioguardi, C. Ji and E. L. Thompson, Journal of the Electrochemical Society, 159, F405 (2012).

A. Kongkanand, J. E. Owejan, S. Moose, M. Dioguardi, M. Biradar and R. Makharia, Journal of the Electrochemical Society, 159, F676 (2012).

A. Kongkanand and P. K. Sinha, Journal of the Electrochemical Society, 158, B703 (2011).

P. K. Sinha, W. Gu, A. Kongkanand and E. Thompson, Journal of the Electrochemical Society, 158, B831 (2011).

A. Kongkanand, Z. Liu, I. Dutta and F. T. Wagner, Journal of the Electrochemical Society, 158, B1286 (2011).

A. Kongkanand, J. Zhang, Z. Liu, Y. Lai, P. Sinha, E. Thompson, R. Makharia, submitted to Journal of the Electrochemical Society (2014).
High-Resolution Mapping of the PFSA Polymer Distribution in PEFC Electrode Layers
Authors: Koestner Roland John , Cullen David A , Kukreja Ratandeep , Minko Sergiy , Meyer Harry M , Liu Zhongyi , More Karren L.
Published: February 2020

Perfluorosulfonic acid (PFSA) ionomer is a key component within the electrode layers of polymer electrolyte fuel cells (PEFCs) since this solid electrolyte provides an efficient proton transport path to the active catalyst sites. Both the average loading on a 100-nm scale as well as the actual film thickness distribution on a 1-nm scale of the PFSA ionomer in the porous layer structure are critical to electrode performance so quantitative measurements of both properties are highly desired.

Scanning transmission electron microscopy (STEM) is one useful tool to map this PFSA distribution in the electrode layer [1]. However, it has long been recognized that fluorinated compounds are sensitive to electron beam radiation damage [2,3]. By maintaining an electron dose below 1x104 e-/nm2 at 100-nm lateral resolution and cooling the specimen below -100ºC, the total fluorine mass loss for Nafion® ionomer is held below 10% a/a whereby the electron beam damage threshold for a typical Pt/C electrode layer is improved by 2-3 orders-of-magnitude at this sample temperature.

Atomic force microscopy (AFM) [4] is a complementary tool suitable to map the Nafion® coverage on a 1-nm length scale on the electrode surface. The adhesion of the AFM tip to Nafion® in air was measured to be very low as the fluorocarbon backbone was preferentially exposed at polymer-air interface.

In this paper, we present ionomer mapping measurements of two common PEFC electrode constructions. Figure 1 shows Pt/C/Nafion® layers at 8 μm dry thickness that are coated from the same electrode ink onto either a decal substrate (CCD) or directly onto the gas diffusion media. The other electrode layer comprises a PtCoMn nanostructured thin film (NSTF) electrode [5] that is overcoated with Nafion® ionomer using a preferred adsorption scheme to a targeted 2.0 nm dry thickness.

Figure 2 shows that a significantly different through-layer ionomer/carbon (I/C w/w) profile is measured by energy-dispersive X-ray spectroscopy (EDS) for the CCD and CCDM electrode layers that can be ascribed to partial permeation of the electrode ink solution into the porous gas diffusion media substrate. In addition, the AFM adhesion measurement in Figure 3 shows a linear increase in ionomer coverage on the NSTF electrode surface to the adsorption limit (at
2 nm dry thickness).

ORNL Research sponsored by (1) the Fuel Cell Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy and (2) the Shared Research Equipment (ShaRE) User Facility, which is sponsored by the Office of Basic Energy Sciences, U.S. Department of Energy.
Characteristics of Paper-Based Lactate-O2 Biofuel Cell and Its Application for Wearable Devise
Authors: Shitanda Isao , Yagi Yuki , Momiyama Misaki , Hoshi Yoshinao , Itagaki Masayuki , Tsujimura Seiya
Published: February 2020

There has been considerable recent interest in wearable biofuel cells based on printing technologies.1 Screen-printing technique has following merits; drawing precise pattern of um order, a wide variety of inks, high reproducibility, and low cost. Thus, screen-printing has been widely used for fabrication of electrochemical devices such as dye-sensitized solar cells, biosensors and corrosion sensor. 2-5

Recently, we prepared a screen-printed paper-based biofuel cell using porous carbon inks and showed its high output power. 6 In the present study, we newly demonstrated a screen-printed paper-based biofuel cell which consisted of lactose oxidase-modified and billirubin oxidase-modified porous carbon electrode fabricated on the paper substrate. Firstly, the characteristics of the bioanode and biocathode were investigated independently by the three-electrode method; the bioanode or biocathode was connected to a potentiostat. A Ag|AgCl reference electrode and Pt wire counter electrode were placed in the electrolyte solution. Then, electrochemical response of the BFC was examined.

References

1. W. Jia, G. Valdes-Ramirez, A. J. Bandodkar, J. R. Windmiller, J. Wang Angew. Chem. Int. Ed., 52, 7233 (2013).

2. M. Itagaki, Y. Nakano, I. Shitanda, K. Watanabe, Electrochim. Acta , 56, 7975 (2011).

3. I. Shitanda, S. Takamatsu, K. Watanabe, M. Itagaki, Electrochim. Acta, 54, 4933 (2009).

4. I. Shitanda, A. Okumura, M. Itagaki, K. Watanabe, Sens. Actu. B-Chem, 139, 292 (2009).

5. I. Shitanda, T. Yamaguchi, Y. Hoshi, M. Itagaki, Chem. Lett. 42, 1369 (2013).

6. I. Shitanda, S. Kato, Y. Hoshi, M. Itagaki, S. Tsujimura, Chem. Comm. 49, 11110 (2013).
Modification of Electrodes for MFC Using Sludge from the Wastewater Treatment Plant
Authors: Ibañez-Redín Glenda Gisela , Chaur Manuel Noe , Bravo Enrique , Lizcano-Valbuena William Hernando
Published: February 2020

Carbon Vulcan XC 72R was modified using several chemical treatments (oxidation in acidic medium, ethylene glycol, 4-aminopyridine and rubeanic acid treatments) changes in the electrochemical behavior and the surface composition were observed. Pieces of carbon tissue were modified with the carbon materials. The pieces of carbon tissue were electrochemically characterized and used as anodes in a single chamber air cathode MFCs (Microbial Fuel Cells ) inoculated with sludge from the Wastewater Treatment plant of La Voragine, yielding a maximum power density of 15.37 mWm-2 and a maximum current density of 61.25 mAm-2 for the cell with the electrode modified with ethylene glycol. To compare the performance of the anodes were measured anodic polarization curves, which showed better performance for the rubeanic acid modified electrode. The lower performance was obtained for the unmodified electrode followed by electrode modified by chemical oxidation. These results suggest a reduction in biocompatibility by the introduction of negatively charged groups.

The results of the cultivation and isolation of microorganisms in the anode showed a greater affinity of the bacteria for the rubeanic acid modified electrode and the exclusive presence of a microorganism in it. Additionally was observed the presence of redox mediators producing bacteria on the electrode modified by oxidative treatment. The results show the influence of the surface composition on the biofilm composition and probably in the electron transfer mechanism.
The Electrolytic Dissociation of 1,4-Cyclohexanedicarboxylic Acid
Authors: Kvaratskhelia Elene , Kvaratskhelia Ramaz , Kurtanidze Rusudan
Published: February 2020

Cyclohexanedicarboxylic acids are widely used as the members of the positive resist radiation-sensitive composition, the coating resinous compositions, for production the high-solid polyurethane coatings for such demanding markets as automotive, transportation, maintenance, and aerospace. In this communication the regularities of electrolytic dissociation of trans-1,4-cyclohexanedicarboxylic acid are studied by the suggested by authors original method for calculation the parameters of dissociation of weak multibasic organic acids with the “overlapping” equilibria effect.

For weak dibasic organic acids the law of dilution for both dissociation steps may be expressed as follows:

where K1 and K2 are the thermodynamic dissociation constants of first and second steps, α1 and α2 are the usual degrees of dissociation of these steps, α′
2 is the “partial” degree of dissociation of second step, c is the total (analytical) concentration of acid, F1 and F2are the quotients of the activity coefficients for the corresponding steps:

The values of the activity coefficients were approximated by the Debye-Huckel equation:

where ai is the cation-anion distance of closest approach, A and B are constants depending on the properties of water at given temperature, ziis the charge of ion. Ionic strength .

According to equations [1] and [2] the degrees of dissociation α1, α2 and α′
2can be evaluated successively by iterative solution of following two quadratic equations:

The equilibrium concentrations of the dissociation products: hydrogen ions, mono- and dianions and undissociated acid molecules can be calculated with the aid of the following equations:

The dissociation constants of trans-1,4-cyclohexanedicarboxylic acid have the following values: K1=6.607×10ˉ5; K2=3.802×10ˉ6.

In Tables I the values of α1, α2, α′
2and pH for the dilute solutions of acid are presented.

Table I. The values of the dissociation parameters

of trans-1,4-cyclohexanedicarboxylic acid

at 16ºC

Concentration, M

α1

α2

α′
2

pH

0.0001
0.0002
0.0004
0.0006
0.0008
0.001
0.002
0.004
0.006
0.008
0.01
0.5507
0.4365
0.3358
0.2849
0.2525
0.2295
0.1691
0.1233
0.1021
0.08926
0.08035
0.03472
0.01826
0.009473
0.006427

0.004875

0.003932

0.002014
0.001030
0.0006954

0.0005267

0.0004246
0.06305
0.04183
0.02821
0.02256
0.01931
0.01713
0.01191
0.008354

0.006811

0.005901

0.005284
4.236
4.046
3.866
3.764
3.693
3.639
3.474
3.314
3.221
3.156
3.106

We suggest also the simple empirical equations for fast approximate calculation of the dissociation parameters of trans-1,4-cyclohexanedicarboxylic acid:
Modified Surfaces by Electrodeposition for Energy Devices
Authors: Innocenti Massimo , Lavacchi Alessandro , Vizza Francesco , Di Benedetto Francesco , Zafferoni Claudio , Foresti Maria Luisa
Published: February 2020

The global environmental concerns and the escalating demand for energy, coupled with a steady progress in renewable energy technologies, are opening up new opportunities for the utilization of renewable energy resources. Electrodeposition is well known for depositing metals and metallic alloys at the industrial level, with a wide range of applications from large area surface treatments to most advanced electronic industries. Electrodeposition of semiconducting materials represents a new challenge, not only from the academic point of view, but also from the economic point of view, since this method presents interesting characteristics for large area, low cost and generally low temperature and soft processing of materials. In this presentation, we exploited alternated electrodeposition of some metals by E-ALD (Electrochemical Atomic Layer Deposition) to obtain thin films, controlling the growth of the structures at the nanometric level. Selective Electrodesorption Based Atomic Layer Deposition (SEBALD [1]) was used to prepare new bimetallic electrodes for fuel cells. This new method of Electrodeposition, recently pointed out in Florence on the base of ECALE method [2], allows to deposit under morphological and compositional control those metals that cannot be deposited at underpotential. We have recently reported the use of nanostructured palladium in the realization of a new “green” and energetically self-sustainable paradigm for the chemical industry based on the electro-oxidation of renewable alcohols [3]. The exploitation of the catalytic properties of palladium toward the oxidation of alcohols strongly depends on the availability of methods capable of generating supported metal nanoparticles with high index facets, as well as selecting size and metal loading. The concomitant control of all these aspects is a major challenge for nanotechnology oriented to catalysis and electrocatalysis.

To achieve these targets we developed a method (Electrochemical Milling and Faceting – ECMF [4]), consisting of an electrochemical post-deposition treatment. Ultimately the purpose of the method is to perform a milling and faceting of the palladium nanoparticles deposited by virtually any known deposition

method.

[1] M. Innocenti, S. Bellandi, E. Lastraioli, F. Loglio, and M. L. Foresti, Langmuir, 2011.

[2] Gregory, B. W.; Stickney, J. L. J. Electronanal. Chem. 1991, 300, 543.

[3] V. Bambagioni, M. Bevilacqua, C. Bianchini, J.

Filippi, A. Lavacchi, A. Marchionni, F. Vizza and P. K.

Shen, ChemSusChem, 3 (2010) 851.

[4] Y.X. Chen, A. Lavacchi, S.P Chen, F. Di Benedetto, M. Bevilacqua, C. Bianchini, P. Fornasiero, M. Innocenti, M. Marelli, W. Oberhauser, .S.G. Sun, F. Vizza.

Angew. Chem. Int. Ed. 2012, 51, 8500 –8504.
A Survey of Materials and Corrosion Issues for Metal Implant Materials
Authors: Kay Lawrence Edward
Published: February 2020

While the materials available to the medical device designer are widely varied, most permanent implant materials are either completely metallic or supported by a metallic structure. This discussion provides a survey of common medical materials in wire form through a comparative study following the ASTM F2129 cyclic potentiodynamic polarization methodology. Additionally, a detailed examination of corrosion issues surrounding the shape memory metal Nitinol are reviewed. The newest development in medical materials focuses on bioabsorbable materials, primarily the nutrient metals magnesium, iron and zinc, that serve their intended purpose, and are then gradually absorbed by the body. These materials present an exceptionally difficult challenge to evaluate as the F2129 techniques are not applicable. Data on recent studies in various media are reviewed.
Electrochemical Reaction of Tris(1,10-phenanthroline)Iron Complexes in Some Amide-Type Ionic Liquids
Authors: Katayama Yasushi , Yoshihara Mami , Miura Takashi
Published: February 2020

Electrochemical behavior of a charged species in ionic liquids have been known to depend on the physicochemical properties of the ionic liquids[1-4]. Diffusion of the charged species is affected not only by the viscosity of the ionic liquids but also by the coulombic interaction between the charged species and the ions composing the ionic liquids. Thus, Stokes-Einstein relation is generally inapplicable to diffusion of charge species in ionic liquids. The electron transfer rates are also influenced by the viscosity and the coulombic interaction, which is considered related to the outer component of reorganization energy. Furthermore, the reaction entropy of the redox couples without change of their coordination environment has been found to relate to the coulombic interaction[5,6]. We have reported these results with tris(2,2'-bipyridine) complexes of iron and ruthenium in some ionic liquids. In the present study, electrochemical reactions of tris(1,10-phenanthroline)iron and tris(2,2'-bipyridine)iron complexes were investigated in 1-butyl-1-methylpyrrolidinium (BMP+) and 1-ethyl-3-methylimidazolium (EMI+) bis(trifluoromethylsulfonyl)amide (TFSA–) ionic liquids in order to elucidate the effects of the charge density of the redox species on electrode kinetics and reaction entropy. The diffusion coefficient of [Fe(phen)3]
n+ was smaller than that of [Fe(bpy)3]
n+ (n = 2 and 3) in BMPTFSA and EMITFSA. The ratios of diffusion coefficients of [Fe(phen)3]3+ to [Fe(phen)3]2+ were larger than those of [Fe(bpy)3]3+ to [Fe(bpy)3]2+, indicating the coulombic interaction of TFSA– with [Fe(phen)3]
n+ is weaker than that with [Fe(bpy)3]
n+ since the size of [Fe(phen)3]
n+ is larger than that of [Fe(bpy)3]
n+. The rate constants for [Fe(phen)3]3+/2+ were close to those for [Fe(bpy)3]3+/2+. On the other hand, the reaction entropy for [Fe(phen)3]3+/2+ was smaller than that for [Fe(bpy)3]3+/2+, reflecting the difference in the charge densities.

References

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

[2] N. Tachikawa, Y. Katayama, and T. Miura, Electrochem. Solid-State Lett., 12, F39 (2009).

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

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

[5] T. Migita, N. Tachikawa, Y. Katayama, and T. Miura, Electrochemistry, 77, 639 (2009).

[6] Y. Yamato, Y. Katayama, and T. Miura, J. Electrochem. Soc., 160, H309 (2013).
Energy Efficient Capture and Release of Carbon Dioxide in Tetraalkyl Phosphonium and Tetraalkyl Ammonium Ionic Liquids
Authors: Rheinhardt Joseph , Buttry Daniel A.
Published: February 2020

Described herein is an electrochemical method for the energy efficient capture and release of CO2 that employs electrochemically-generated thiolates as the CO2 capture agents. In N,N-dimethylformamide at glassy carbon electrodes the onset of CO2 reduction precludes capture by electrochemically generated thiolates. This is not the case in tetraalkyl phosphonium and tetraalkyl ammonium ionic liquids. In these media saturated with CO2, electrochemical reduction of disulfides to thiolates proceeds via a two-electron process with potential inversion.1 One-electron reduction of the disulfide results in dissociative electron transfer (DET), the first step of which is the formation of a short-lived radical anion.2 The S–S σ bond of the radical anion is subsequently cleaved leading to a thiolate and a sulfur-based radical.2 Resultant sulfur radicals are reduced at potentials positive of the potential applied for reduction of the corresponding disulfide. Thus, electrochemical thiolate generation is best formulated as a two-electron reduction with concomitant disulfide cleavage.3 In this presentation we will show that the potent, electrochemically generated sulfur nucleophiles capture CO2 via a facile SN2 reaction leading to formation of a thiocarbonate (Scheme 1). We will further demonstrate that the mechanism for the release of CO2 and regeneration of the disulfide is the one-electron Kolbe oxidation of the thiocarbonate followed by coupling of two sulfur radicals (Scheme 2).4 Cyclic voltammograms show that thiocarbonate oxidation occurs at potentials positive of thiolate oxidation. Increases in the peak-to-peak separation between thiolate oxidation and thiocarbonate oxidation have been ameliorated by targeted modifications to the disulfide.

(1) Evans, D. H. Chem. Rev.
2008, 108, 2113–2144.

(2) (a) Antonello, S.; Benassi, R.; Gavioli, G.; Taddei, F.; Maran, F. J. Am. Chem. Soc.
2002, 104, 7529–7538. (b) Meneses, A. B.; Antonello, S.; Arévalo, M. C.; Gonzáles, C. C.; Sharma, J.; Wallette, A. N.; Workentin, M. S.; Maran, F. Chem. Eur. J.
2007, 13, 7983–7995.

(3) Hall, G. B.; Kottani, R.; Felton, G. A. N.; Yamamoto, T.; Evans, D. H.; Glass, R. S.; Lichtenberger, D. L. J. Am. Chem. Soc.
2014, 136, 4012–4018.

(4) Vijh, A. K.; Conway, B. E.; Chem. Rev.
1967, 67, 623–664.
The Composition of the Second Coordination Sphere and Charge Transfer of the Nb(V)/Nb(IV) Redox Couple in Alkali Halide Melts
Authors: Popova Anna V. , Kremenetsky Vyacheslav G. , Kuznetsov Sergey A.
Published: February 2020

The effect of the second coordination sphere and the working electrode nature on the standard rate constants of charge transfer (k
s) for the Nb(V)/Nb(IV) redox couple in chloride-fluoride and fluoride melts was studied.

The standard rate constants for the Nb(V)/Nb(IV) redox couple were calculated based on cyclic voltammetry data and the Nicholson’s equation.

The following unusual series of the standard rate constants of charge transfer is experimentally determined in chloride-fluoride melts:

k
s (KCl) < k
s (CsCl) < k
s
(NaCl-KCl).

Ab initio calculations carried out by using PC Gamess/Firefly quantum chemical program showed that charge transfer activation energies can actually change in nonmonotonic manner in the series sodium-potassium-cesium, which leads to nonmonotonic change of the charge transfer rate constants in chloride-fluoride melts.

In pure fluoride melts, the following dependence of the standard rate constants was obtained using cyclic voltammetry:

ks
(CsF) < ks
(KF) < ks
(NaF-KF).

It has been established that the standard rate constants of charge transfer increase with increasing temperature, as well as with replacement of the glassy carbon electrode with a platinum one.

Acknowledgments

The work was financially supported by the Russian Foundation for Basic Research (project 12-08-01178-а).
The High Temperature Operation of Lithium Secondary Batteries with Using Ionic Liquids
Authors: Matsumoto Hajime , Kubota Keigo
Published: February 2020

Ionic liquids (ILs) composed of perfluoroanion such as BF4
− and bis(trifluoromethylsulfonyl)amide (([(CF3SO2)2N]−, Tf2N−) have attracted attention as less flammable and less volatile electrolyte for a lithium secondary battery for past decade. Especially, Tf2N- forms ILs not only 1-ethyl-3-methylimidazolium (C2mim+), but also various aliphatic quaternary ammonium (AQA+). The AQA-Tf2N exhibited large apparent electrochemical windows enough wide to use a solvent free electrolyte for a 4 V-class battery such as a LiCoO2 half-cell. Though the rate properties of the cell at room temperature were much lower than that for a conventional organic solvents, another promising ILs composed of bis(fluoromethylsulfonyl)amide (f2N−) are dramatically improved the rate property of the cells using ILs. However, it should be focused on not only the rate performance but also the actual thermal stability of the cells using ILs, which might not depend on only the thermal stability of ILs.[1]

In this presentation, we would like to show the effect of cationic species of Tf2N--ILs on the cycle stability of a cathode half-cell at high temperature over 100 °C. For this purpose, a conventional LiFePO4 cathode composed of polyvinylidene fluoride (PVDF) (KUREHA, #1120) as binder and acetylene black (AB) as the conductive additive. We found that the rate property of the LiFePO4half-cells were much improved over 85 °C and also the cycle performance of the cells over 100 °C were much depend on the kind of cation in ILs.

Acknowledgements

A part of this work was supported by the R&D project for Li batteries by NEDO of Japan (Li-EAD) and Advanced Low Carbon Technology Research and Development Program (ALCA) of Japan Science and Technology Agency (JST).

Reference

[1] H. Matsumoto, in Electrolytes for Lithium-ion Batteries, eds. T. R. Jow, K. Xu, O. Borodin and M. Ue, Springer, 2014, ch.4 and references therein.
Inorganic-Organic Hybrid Ionic Liquid Electrolytes for Na Secondary Batteries
Authors: Matsumoto Kazuhiko , Taniki Ryosuke , Nohira Toshiyuki , Hagiwara Rika
Published: February 2020

Sodium secondary batteries are attracting more and more attraction as energy storage devices for stationary use and electric vehicles due to high abundance and low cost of sodium resources as well as the low redox potential of Na+/Na. Ionic liquid electrolytes are attractive to improve the safety issues of sodium secondary batteries, owing to their unique properties such as low flammability and low vapor pressure [1-3]. Our recent works suggest FSA- (FSA- = bis(fluorosulfonyl)amide anion) based ionic liquids, such as Na[FSA]-K[FSA] and Na[FSA]-[C3C1pyrr][FSA] (C3C1pyrr+ = N-propyl-N-methylpyrrolidinium cation) systems, exhibit good physical and electrochemical properties as electrolytes for Na secondary batteries [4-6]. This study will present a new series of inorganic-organic hybrid ionic liquids as electrolytes for Na secondary batteries.

Four FSA salts of organic cations, N6111
+ (hexyltrimethylammonium), N4422
+ (dibutyldimethylammonium), AS[4.5]+ (azoniaspiro[4.5]nonane), and C2C1im+ (1-ethyl-3-methylimidazolium), are mixed with Na[FSA]. In all the cases, a wide liquid temperature range around room temperature was observed in a certain x(Na[FSA]) range. Ionic conductivity and viscosity increase and decrease with decreasing x(Na[FSA]), respectively. The highest ionic conductivity was observed for the Na[FSA]-[C2C1im][FSA] system. Electrochemical windows are around 5 V and Na metal deposition and dissolution are observed at the cathode limit. The efficiency of Na metal deposition and dissolution is improved by increasing temperature due to suppression of dendritic Na metal deposition.

[1] L.G. Chagas, D. Buchholz, L.M. Wu, B. Vortmann, S. Passerini, J. Power Sources, 247 (2014) 377-383.

[2] S.A.M. Noor, P.C. Howlett, D.R. MacFarlane, M. Forsyth, Electrochim. Acta, 114 (2013) 766-771.

[3] D. Monti, E. Jonsson, M.R. Palacin, P. Johansson, J. Power Sources, 245 (2014) 630-636.

[4] C. Ding, T. Nohira, K. Kuroda, R. Hagiwara, A. Fukunaga, S. Sakai, K. Nitta, S. Inazawa, J. Power Sources, 238 (2013) 296-300.

[5] T. Yamamoto, T. Nohira, R. Hagiwara, A. Fukunaga, S. Sakai, K. Nitta, S. Inazawa, J. Power Sources, 217 (2012) 479-484.

[6] C.Y. Chen, K. Matsumoto, T. Nohira, R. Hagiwara, A. Fukunaga, S. Sakai, K. Nitta, S. Inazawa, J. Power Sources, 237 (2013) 52-57.
Synthesis and Characterizations of Cobalt Films Electrochemically Deposited from Aqueous and Non-Aqueous Media
Authors: Dushatinski Thomas , Huff Clay , Abdel-Fattah Tarek M
Published: February 2020

Optically absorbent materials have applications in both high-resolution optical imaging and photonic conversion systems. In optical imaging, these materials can be used to reduce the amount of parasitic light. Reducing the parasitic light present in a system increases the possible resolution, making highly optically absorbent materials important for advancements in imaging devices, such as telescopes and optical microscopes. Cobalt films convert absorbed light to heat and transfer it effectively because of their thermal conductivity. This property combined with the characteristics of novel non-aqueously deposited cobalt films (NADCFs) has applications in thermal photonic conversion systems. The characteristics of novel NADCFs are much different than traditional aqueously deposited films (ADCFs) and have much better optical absorbance that can be attributed to their microstructures porosity.

The two films were characterized using UV-Vis Spectroscopy to determine percent absorbance, energy dispersive x-ray spectroscopy (EDS) to infer density, and scanning electron microscopy (SEM) to determine microstructure and thickness. SEM micrographs of the cobalt micro-particles differed depending on solvent (Figure 1). The SEM images and EDS spectra together show a less dense accumulation of micro-particles in the NADCFs compared to the ADCFs. Greater porosity in the 180µm thick NADCF compared to the 115µm thick ADCF was confirmed by the transmission of the x-ray beam in EDS to the copper substrate, showing copper peaks. Thicknesses were determined using cross-section analysis in SEM. The optical absorbance of both films as produced were measured. NADCFs had >99% absorbance and the ADCFs had 95% absorbance at 490nm.

References:

[1] Florea, A.; Anicai, L.; Costovici, S.; Golgovici, F.; Visan, T. 2010, Surf.
Interface Anal, 42, 1271-1275

[2] Abdel-Fattah, T.M.; Crooks, R. 2010, ECS Trans, 33, 571

[3] Abdel-Fattah, T.M.; Loftis, J.D. 2010, ECS Trans, 25, 57

[4] Abdel-Fattah, T.M.; Loftis, J.D.; Mahapatro2010, ECS Trans, 25, 57

[5] Abdel-Fattah, T.M.; Loftis, J.D. 2009, ECS Trans. 25, 327

[6] Damiano, B.; Wixtrom, A.; Abdel-Fattah, T. 2012,
ECS Trans.

[7] Jiovannini H.; Amra,C. 1998, Applied Optics. 37(1), 104-105.
An Overview of the REFINE Project --- The Sustainable Reduction of Spent Fuel Vital in a Closed Loop Nuclear Energy Cycle
Authors: Hu Di , Stevenson Anthony , Chen George Zheng
Published: February 2020

Widely known as the FFC Cambridge Process, direct electrochemical reduction of solid metal compounds, particularly oxides, in molten salts has been studied by many research groups around the world for purposes of metal extraction and refining, and alloy synthesis. Significant research and commercial processes have been achieved in the past 15 years, although understanding of the underline science and technological improvement of the process have continued. Particularly, as shown in Figure 1, it has been recognised and incorporated as a key technique in the recently launched REFINE consortium research programme that is supported by the Research Councils in the UK (RCUK). Because the technological objectives of REFINE are well beyond metal extraction, new opportunities and challenges can be anticipated. This presentation reviews relevant recent progresses in the field, and reports on preliminary findings on several fronts of the research challenges, including a new way of separation of mixed metal oxides via partial reduction, possible mitigation of the impact of the electronic conductivity of molten salts, and improvements in experimental techniques. All these are discussed in the context of efficiency improvement of the process in relation to the REFINE programme.
Electrochemical Fluorination of Uranium to UF6
Authors: Martinez-Rodriguez Michael J. , Olson Luke Christopher , Gray Joshua R. , Garcia-Diaz Brenda L.
Published: February 2020

The development of efficient and environmentally benign methods to reprocess used nuclear fuel will be enabling technologies for the nuclear renaissance. The primary large scale method for processing used nuclear fuel is aqueous and generates large volumes of high level radioactive waste. The use of electrochemical and fluorination methods for reprocessing used nuclear fuel have been proposed and researched by various groups, but combinations of electrochemical and fluorination methods have not been investigated. Fluorinating agents are extremely potent oxidizers and may electrochemically fluorinate metallic used nuclear fuel with no input of electricity. A galvano-fluorination process has been developed at Savannah River National Laboratory. This electrochemical non-aqueous process enables efficient gas phase uranium recovery while allowing for control of the reaction. Thermodynamic modeling of the electrochemical fluorination process has shown UF6 to be the first gaseous fission product produced during fluorination. Further thermodynamic modeling was used to determine the feasibility of oxide reduction required for oxide fuel before electrochemical fluorination and for experiments. A chemical reactor system for electrochemical fluorination of U with NF3 in a fluoride molten salt was constructed along with vessels for product collection and analysis. This work has proven that an electrochemical reaction happens between U and NF3 which confirms the feasibility of electrochemical fluorination and the development of a processing scheme.
"Core-Shell" ORR Nano-Electrocatalysts Based on a PtNi Carbon Nitride "Shell" and Cu NP "Core"
Authors: Di Noto Vito , Negro Enrico , Vezzù Keti , Bertasi Federico
Published: February 2020

One of the most severe bottlenecks in the operation of proton exchange membrane fuel cells (PEMFCs) is the sluggish kinetics of the Oxygen Reduction Reaction (ORR). Thus, suitable ORR electrocatalysts are required in order to obtain PEMFCs able to yield a sufficiently high performance [1]. State-of-the-art ORR electrocatalysts for application in PEMFCs are obtained by supporting Pt nanocrystals on active carbon supports characterized by a very large surface area [2]. However, despite extensive investigations the performance of these electrocatalysts does not meet yet the strict requirements necessary for a large-scale application of PEMFC technology. A new preparation protocol has been proposed recently to obtain nano-electrocatalysts with a well-controlled chemical composition, based on the pyrolysis and activation of hybrid inorganic-organic precursors. The resulting carbon nitride nano-electrocatalysts thus prepared show an outstanding ORR performance both in “ex-situ” studies and in a single-cell configuration [3]. In this work, a new family of multimetal carbon nitride nano-electrocatalysts is described. The materials are synthesized by pyrolysis of a hybrid inorganic-organic precursor including Pt and Ni atoms impregnating Cu nanoparticles acting as the support. The final ORR electrocatalysts are obtained after an extensive electrochemical dealloying activation process. The products are fully characterized before and after the activation processes. The chemical composition of the electrocatalysts is determined by Inductively-Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and microanalysis. The morphology is investigated by High-Resolution Scanning Electron Microscopy (HR-SEM) and High-Resolution Transmission Electron Microscopy (HR-TEM). The structure is probed by powder X-Ray Diffraction (XRD). The electrochemical performance of the electrocatalysts in the ORR is determined both by “ex-situ” measurements carried out by cyclic voltammetry with the rotating ring disk electrode (CV-TF-RRDE method) and by “in-situ” fuel cell studies in a PEM single-cell configuration. Preliminary results indicate clearly that the proposed electrocatalysts show a remarkable ORR performance, which is significantly enhanced in comparison with the Pt/C reference both in terms of overpotential and selectivity in the 4-electron mechanism of the ORR (see Figure 1).

REFERENCES

[1] J. X. Wang, F. A. Uribe, T. E. Springer, J. Zhang, R. R. Adzic, Faraday Discuss.
140, 347 (2008).

[2] J. Zhang, Front. Energy
5, 137 (2011).

[3] V. Di Noto, E. Negro, Electrochim. Acta
55, 7564 (2010).
Importance of Specific Interactions between Support, Metal Oxide Nanostructures and Noble Metal or Organometallic Sites in Efficient Electrocatalytic and Bioelectrocatalytic Reduction of Oxygen
Authors: Kulesza Pawel J.
Published: February 2020

Systems utilizing carbon nanostructures (e.g. nanotubes) and noble metal nanoparticles can form advanced electrocatalytic materials with well-defined composition, structure and thickness. We explore here the ability of inorganic structures to stabilize and derivatize metal (Au, Pt, Pd) and carbon nanostructures. Among inorganic systems, polyoxometallates of tungsten are attractive since they can not only adsorb irreversibly on solid surfaces but also exhibit reversible stepwise multi-electron transfer reactions. The concept of the layer-by-layer formation of hybrid inorganic assemblies composed of anionic polyoxometallate-protected carbon nanotubes (or metal nanoparticles) and ultra-thin nanostructures of positively charged metal oxide (vanadia, titania, zirconia) nanostructures (alone or in combination with tungsten oxide) will be described and discussed here. The resulting novel composite materials are characterized by fast dynamics of charge propagation. When it comes to the electrocatalytic reduction of oxygen, polyoxometallates can also be applied to stabilize and link Pt, Pd and various alloyed Pt-based catalytic nanoparticles.

To produce bioelectrocatalytic materials for oxygen reduction, we explore unique properties of biofilms, i.e. polymeric aggregates of microorganisms, in which cells adhere to each other on the electrode surfaces. Such systems are characterized by extracellular electron transfers involving c-type cytochromes (heme-containing proteins). Biofilms grown on inert carbon electrode substrates tend to exhibit electrocatalytic properties towards oxygen and hydrogen peroxide reductions in neutral media. The processes have been found to be further enhanced by introduction of multi-walled carbon nanotubes (MCNTs) that are modified with ultra-thin layers of organic (e.g. 4-(pyrrole-l-yl) benzoic acid. We expect here attractive electrostatic interactions between carboxyl-group containing anionic adsorbates and positively charged domains of the biofilm with c-type cytochrome enzymatic sites. Coexistence of the above components leads to synergistic effect that is evident from positive shift of the oxygen reduction voltammetric potentials and significant increase of voltammetric currents. Most likely, the reduction of oxygen has been initiated at the molecular (e.g. intentionally added metalloporphyrin redox centers), whereas the undesirable hydrogen peroxide intermediate are further decomposed at the cytochrome sites.

Acknowledgement

We appreciate collaboration with Krzysztof Miecznikowski, Adam Lewera, Beata Dembinska, Jakub Sek, and Anna Dobrzeniecka from Faculty of Chemistry, University of Warsaw.
Mediated Electron Transfer for ORR Catalysis with Transition-Metal Macrocycles
Authors: Elbaz Lior
Published: February 2020

The search for a non-precious-metal based, oxygen reduction reaction (ORR) catalysts for fuel cells has grown due to rising prices of the catalysts used today which is derived from their scarcity. Although very active, platinum, which is considered to be the state-of-the-art catalyst for ORR, is not used in biological systems almost at all, especially not in processes which involve the catalysis of ORR. One of the reasons may be availability, another may be reaction selectivity. Instead, biological systems usually use transition metal complexes to catalyze such reactions. These are normally a part of an elaborate system of electron donors, electron acceptors and electron mediators, described in electron transfer chains and cycles. Since the beginning of the search for non-precious-metal catalyst, one family of catalysts has always been interesting as a possible candidate to replace precious metal catalysts – transition metal macrocycles (TMMs). This is due to the significant roles these macrocycles play in biological systems, which in many cases involve ORR catalysis.

In the past years we have worked on the study of the interaction between various TMMs and redox active molecules known as electron donors in catalytic cycles. The interaction between quinones and other possible electron donors such as imidazoles and thiophenes have shown to enhance the ORR activity of TMMs. Figure 1 shows an RRDE measurement obtained with cobalt porphyrin (CoTPPS) interacting with hydroquinone on the surface of carbon electrode. In comparison to its ORR activity without the hydroquinone layer on the carbon (not shown), the CoTPPS’s half wave potential is shifted by more than 400mV to a more positive potential. This shift is attributed to the interaction with the electron donor.

In this talk, we will present our most recent work on the study of the interaction between TMMs and electron donors and its effect on ORR electrocatalysis.
An Efficient Silver-Metal Oxide Hybrid Bifunctional Catalyst for Alkaline Air-Electrodes: DEMS and RRDE Study
Authors: Baltruschat Helmut , Amin Hatem M.A. , Zan Lingxing , Ayata Sevda , Soltani Mohammad
Published: February 2020

In order to develop a commercial catalyst for metal-air batteries, stability, good round-trip efficiency, high activity and fast kinetics for OER/ORR should be satisfied. Since the high cost of Pt limits its industrial application, several metal oxides of the perovskite and spinel type such as Co3O4 have been tested as bifunctional catalysts.[1] Silver is a non-precious and active catalyst for ORR. Thus, coupling of silver and metal oxide like Co3O4 revealed to be a promising catalyst for both ORR and OER. This carbon-free mixed catalyst showed high activity and good stability in alkaline media. 10% and 20% of Co3O4 was found to be optimum for ORR and OER, respectively. RRDE data showed that ORR follow the direct 4-electron pathway with negligible peroxide formation. About 60mV shift in half wave potential of ORR for the 10% catalyst compared to pure silver was achieved. DEMS results monitored the OER onset. Tafel slopes of about 80 mV/dec at low overpotentials were obtained for the mixed catalysts.

In further model experiments we studied the activity of the spinel on smooth Ag and also other metal electrodes confirming the synegetic effect. Experiments with a variety of perovskites yielded similar results.

References:

[1] F.H.B. Lima, J.F.R. de Castro, E.A. Ticianelli, Journal of power sources 161(2006)806
Preparation of TaOx by Electrochemical Technique and Its Application to Electrocatalytic Oxygen Reduction
Authors: Awaludin Zaenal , Safuan Mohd , Ye Xiao , Okajima Takeyoshi , Ohsaka Takeo
Published: February 2020

Here we demonstrate a new and simple technique for preparing a tantalum oxide (TaOx)-based electrocatalyst at room temperature for oxygen reduction reaction (ORR) by electrochemical technique [1-4]. The Ta2O5 on the as-prepared deposits was reduced by electrolysis at potential of −0.6 V vs. Ag|AgCl|KCl(sat.) for 12 h generating a smoother and thinner layer of its reduced species (TaOx) (Fig. 1). The treated TaOx exhibits a high ORR activity in acidic and alkaline solutions as seen from a fairly high onset potential (0.87 V vs. RHE) in comparison with that (0.98 V) at a commercially available Pt/C catalyst. By rotating ring-disk electrode voltammetric measurements, it can be concluded that this oxide possesses an almost four-electron ORR electrocatalysis at potential above 0.8 V vs. RHE and a two-electron ORR becomes significant gradually as the potential is increased negatively. The obtained results demonstrate that the present “treated” TaOx is expected as a promising electrocatalyst for ORR in PEMFCs even though its electrocatalytic performance needs to be improved significantly further to replace the Pt/C.

Fig. 1 Schematic illustration of the electrochemical preparation of TaOxelectrocatalyst for ORR.

Acknowledgement

The present research was financially supported by Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.

References

1) Z. Awaludin, M. Suzuki, J. Masud, T. Okajima and

T. Ohsaka, J. Phys. Chem. C, 115, 25557 (2011).

2) Z. Awaludin, J.-M. Sheng Moo, T. Okajima and

T. Ohsaka, J. Mater. Chem. A, 1, 14754 (2013).

3) J. G. S. Moo, Z. Awaludin, T. Okajima and T. Ohsaka, J. Solid State Electrochem., 17, 3115 (2013).

4) Z. Awaludin, T. Okajima and T. Ohsaka,

J. Power Sources, in press.