bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Morphological Evolution of Hybrid PEM by Current Sensing Atomic Force Microscopy
Authors: Kwon Osung , Lee Sang C. , Kim Joo Gon , Son ByungRak , Park Sam
Published: February 2020

The high temperature proton exchange membrane fuel cell (HT-PEMFC) is a key of solving corrosion problem in catalyst layer from CO Poisonning. The key issue of HT-PEMFC is developing novel proton exchange membrane which has good proton conductivity under dry condition and thermal properties compare with Nafion. Sulfonated graphene (S-graphene) and Nafion hybrid membrane is developed in our previous work. The proton conductivity of S-graphene and Nafion hybrid membrane is five times larger than pristine Nafion at 20 % RH. In addition, the morphological variation due to hybridization of Nafion and S-graphene is observed by using non-contact mode AFM. The morphological variation might induce the ionic channel network variation on the membrane. We measured and analyzed ionic channel network evolution in the membrane by hybridization. Nafion is perm selective membrane due to its heterogeneous structure such as hydrophobic backbone and hydrophilic side chain. The side chain can create ionic channel network which is source of proton conductivity when the membrane is hydrated and the structure of ionic channel network can vary with water faction on the membrane. Thus, in-situ and accurate observation for ionic channel network evolution is required. For in-situ and accurate measurement, we designed PEMFC mimicking method by using current sensing atomic force microscopy (CS-AFM). The pt-coated tip/membrane/catalyst layer can created nano-sized PEMFC. Extremely small tip can act as single Pt catalyst and it simultaneously can detect proton conductivity variation in the ionic channels. In this study, the proton conductivity distribution of S-graphene and Nafion hybrid membrane can measure and compared with the proton conductivity distribution of pristine Nafion. Then the result is analyzed by using statistical method.
Fracture Properties of Fuel Cell Membranes
Authors: Singh Yadvinder , M.H. Khorasany Ramin , Alavijeh Alireza Sadeghi , Kjeang Erik , Wang Gary , Rajapakse Nimal
Published: February 2020

Understanding the crack propagation behavior of common perfluorosulfonic acid (PFSA) ionomer membranes under hygrothermal and mechanical cyclic loading is of vital significance in designing more durable fuel cell stacks (1). Hence, we have developed a test procedure to shed light on the crack propagation characteristics of membranes as a function of loading and environmental conditions. Rectangular specimens with a width of 10 mm and cracks with an average length of 0.7 mm on both sides are used. The specimens are placed under cyclic mechanical loading in a controlled level of environmental conditions (temperature and humidity). The crack propagation rate in the membrane is measured as a function of temperature, humidity and the amplitude of mechanical loading (Figure 1). It is found that a small linear decrease in the magnitude of the force results in an exponential decrement in the crack propagation rate. Furthermore, for a given state of mechanical load, it is found that increasing the relative humidity and/or temperature can significantly increase the crack propagation rate.

In a parallel study, a fracture mechanics-based model capable of simulating the in-situ crack initiation and propagation in the membrane during fuel cell operation is also developed. The elastic-viscoplastic nature of PFSA membranes is well-established in (2). A finite element method (FEM) based constitutive model that can simulate this behavior is used to relate the stress and strain at different environmental conditions (3). Numerical simulations reveal the presence of cyclic mechanical stresses within the membrane due to dynamic hygrothermal conditions present in a running fuel cell that can cause the initiation and propagation of cracks through mechanical membrane degradation. The dynamic stress-field thus obtained is coupled with the fracture mechanics model. In-situ test cases for various temperature, humidity and strain rate conditions are run to fully understand their effect on crack propagation rates and ultimate failure of the membranes.

Acknowledgements:

This research is supported by Ballard Power Systems and the Natural Sciences and Engineering Research Council of Canada through an Automotive Partnership Canada (APC) grant.

References

1. R. Borup, J. Meyers, B. Pivovar, Y. S. Kim, R. Mukundan et al, Chem. Rev.
107 3925 (2007).

2. M.A. Goulet, R.M.H. Khorasany, C. De Torres, M. Lauritzen, E. Kjeang, G.G. Wang, N. Rajapakse, J. Power Sources
234 38 (2013).

3. R.M.H. Khorasany, M.A. Goulet, A.S. Alavijeh, E. Kjeang, G.G. Wang, R.K.N.D. Rajapakse, J. Power Sources
252 176 (2014).
Pore–Filling and Thermally Cross–Linked Polyethersulfone Membranes with High Ion Exchange Capacity and Thermal Stability for PEFCs
Authors: Ando Shinji , Arima Daisuke , Kuroki Hidenori , Ohashi Hidenori , Yao Shigeru , Yamaguchi Takeo
Published: February 2020

Polymer electrolyte membrane fuel cells (PEFCs) have attracted considerable attention due to their high efficiency and clean electric generating system. Especially, in terms of the catalytic activity and water management, there is a great demand for operation under high temperature and low relative humidity. Under such situation, we recently succeeded in the development of heat–resistant electrolyte membrane (PI-CLSPES) with high ion exchange capacity (IEC) from porous polyimide (PI) substrates and highly sulfonated polyethersulfones (SPES150: IEC = 4.9meq/g) by using both polymer-filling and thermal cross–linking methods. The PI substrate can be prepared by using the viscolastic phase separation phenomenon: multi-stage solvent replacement of polyammic acid (PAA) cast film into N-methyl-2-pyrrolidone (NMP) and methanol, followed by thermal treatment. We found that the changes in viscosity of PAA solution, thickness of PAA cast film and immersion time afford the PI substrates with various pore sizes. On the other hand, the SPES150 membrane with high IEC is obtained by further sulphonation of sulfonated poly(arylene ether sulfone) (SPES50) in concentrated sulfuric acid, and allowed for impregnation into the pores of the porous PI substrate. The SPES150 inside the PI pores can be cross-linked between the sulfonic acid and phenyl groups by appropriate thermal treatment, and consequently, lead to the high thermal stability and suppression of membrane swelling. Moreover, the pore-filling and cross-linked membranes still retain the high IEC, and displayed the superior proton conductivity under high temperature comparable to that of Nafion. The detailed proton conducting behavior of the polymer electrolyte membranes as well as their structural analysis will be presented.
In-Situ Raman Spectroscopy Probing of Solid Oxide Electrolysis Cells
Authors: Manerova Jevgenija , Cumming Denis J , Sinclair Derek C , Elder Rachael H
Published: February 2020

Solid oxide electrolysis cell (SOEC) technology is a promising route for sustainable recycling of carbon dioxide and steam into synthetic fuels and commodity chemicals via syngas (H2+ CO) production. This technology is based on the reverse polarity of the prominent solid oxide fuel cell (SOFC) and commonly consists of a porous Ni/YSZ cathode, dense YSZ electrolyte and porous LSM/YSZ anode.

High temperature co-electrolysis of CO2 and H2O is a complicated process and has not yet been fully understood. This is due to a number of reactions that take place simultaneously: water electrolysis, carbon dioxide electrolysis and the reverse water-gas shift reaction (rWGS CO2 + H2 ↔ CO + H2O). Other possible reactions driven by the equilibrium may include the Bosch reaction (CO + H2 ↔ C(s) + H2O) and Boudouard reaction (2CO ↔ CO2 + C(s)).

Carbon deposition on the nickel-cermet surface of SOECs can severely degrade the performance of the cell by deactivating the reaction sites. Recent work by Tao et al. has shown that, at high current densities and conversion efficiencies of CO2 and H2O to CO and H2, carbon formation on the surface of Ni/YSZ fuel electrode is likely to occur [1].

SOECs are typically analyzed in-situ using electrochemical impedance spectroscopy and current-voltage characteristics and ex-situ using scanning electron microscopy to obtain information about cell’s surface topography and composition. However, these techniques are not able to provide conclusive information about the processes occurring during operation of the cell.

In this work we aim to use in-situ Raman spectroscopy alongside traditional electrochemical techniques to probe the surface species of the SOEC electrodes for carbon impurities deposition and provide insight into the fundamental processes and reaction pathways that occur during high temperature (700 – 850 oC) co-electrolysis of CO2 and steam. In-situ Raman spectroscopy is also applied to characterize structural changes and material transformations during SOEC operation.

The particular area of interest is the triple phase boundary (TPB), where the electrochemical reactions take place. Accessing the TPB is challenging due to high operation temperatures and the depth of laser penetration into the sample.

The experimental setup with optical access for the Raman microscope will be discussed in detail as well as the correlation of in-situ spectroscopic data with the electrochemical information obtained from the SOECs.

References

[1] Tao Y., S. D. Ebbesen, and M. B. Mogensen, 2014, J. Electrochem. Soc. 161 (3), F337 – F343.
Sample Preparation Method to Measure Strain of P-Channel with Esige by Nano Beam Diffraction
Authors: Lee Kilho
Published: February 2020

The quantitatively analysis of embedded SiGe (eSiGe) strain was performed by nano beam diffraction (NBD). We have confirmed the best condition of sample preparation for the NBD measurement for strained p-MOSFET. The thickness of sample must be thick enough to prevent stress relaxation by electron beam.

As a result, we could obtain very stable strain variation ±0.1% at unstrained silicon(Si) region.

We also found that damaged layer caused by focused ion beam (FIB) milling process have a crucial role

in the NBD measurement.

Thus, low energy FIB milling condition was optimized for reducing surface damaged layer of the

specimen. We have found the best sample conditions, thickness above 260nm and low energy FIB milling

for sample preparation.

I. INTRODUCTION

II. EXPERIMENTAL

III. RESULTS AND DISCUSSIONS

3.1 Strain relaxation on sample thickness

3.2 Strain sensitivity related to damaged layer

3.3 Strain profile at p-channel with eSiGe

‡W. Conclusion
Study of the Substrate Effect in the KCl Adsorption onto Single-Crystal and Polycrystalline Gold Electrodes
Authors: Gomez-Zamudio Felipe , Alvarez-Casillas Cesar , Soto-Estrada Adriana , Casillas Norberto , Barcena-Soto Maximiliano , Larios-Duran Erika Roxana
Published: February 2020

Electron transfer kinetics in electrochemical systems is ubiquitous to natural and industrial processes. Thus a deep knowledge of all stages involved in the charge transfer at the electrode solution interface, which includes mass transport, adsorption and the role of the electrical double layer is highly desirable [1]. In particular, adsorption and the electrical double layer play a distinctive role in the charge transfer at electrode/solution interfaces, since they are essential part of reaction mechanisms, especially for reactions where more than one electron is transferred. Fueled by the importance of adsorption and the electric double-layer in the electrode kinetics, there has been published in the literature several works, but mainly focused on thermodynamic rather than kinetics [2-4].

Here a qualitative study of the effect of the substrate and surface heterogeneities in the adsorption of chloride ions on gold surfaces is presented. With this goal in mind, we have performed a study of the adsorption of chloride ions at different concentrations (1 mM, 10mM 0.1M) disolved in HClO40.5 M on the surfaces of polycrystalline (pc) and gold (111) single crystal. Our results include the characterization of the system by using classic electrochemical techniques, such as cyclic voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and the novel intermodulated techniqued called Interfacial Capacitance Modulation (MIC) [5].

Figure 1 shows a comparison between the typical voltammetric responses as well as the double-layer capacitance vs. polarization behavior for polycristalline and (111) gold electrodes in contact with HClO4in absence and presence of KCl, respectively.

After this characterization, EIS and MIC measurements are carried out. All our results are discussed qualitatively based on the relaxation of the double layer capacitance as a function of chloride ion concentration on the electrode solution interface.

REFERENCES:

[1] F.C. Anson, Acc. Chem. Res. 8 (1975) 400.

[2] D.C. Grahame, Chem. Rev. 41 (1947) 441.

[3] J. Lipkowski, W. Schmickler, D.M. Kolb, R. Parsons, J. Electroanal. Chem. 452 399, (1998) 193.

[4] T. Pajkossy, D.M. Kolb, Electrochim. Acta 54 (2009) 3594.

[5] E.R. Larios-Durán, R. Antaño-López, M. Keddam, Y. Meas, H. Takenouti, V. Vivier. Electrochim. Acta 55, (2010) 6292.
Electrodeposition of Highly Efficient Nanostructured Thermoelectric Materials
Authors: Nandhakumar Iris , Burton Matthew , White Neil
Published: February 2020

There is overwhelming evidence that our increasing consumption of fossil fuels and the associated emission of carbon dioxide is leading to climate change. This has brought new urgency to the development of clean, renewable sources of energy. Thermoelectric (TE) materials are an important class of materials that can directly convert thermal waste heat into useful electrical energy. With approximately 15 terawatts of available energy being lost to the environment as heat the potential for TE materials in sustainable waste-heat-recovery systems such as TE power generation is huge. However, barriers exist to the widespread adoption of TE technology which is due to the low efficiency of current TE materials. Clearly a step change in the cost and performance of TE materials is required to make them more economically viable and to promote their wider adoption in a number of application areas. In the current work we propose to achieve this by 1. employing electrodeposition as a low-cost, low-temperature route to the fabrication of highly efficient TE materials from, abundant, non-toxic and cheap materials and by employing soft-template directed nanostructuring to produce TE materials.
Structure and Architecture Driven Metallic Bonding and Ligand Effects in Low-Dimensional Platinum Group Metal Catalyst
Authors: Alamgir Faisal M
Published: February 2020

Whether grown as clusters or ultrathin films, extremely small quantities of active elements exhibit changes in catalytic activity that arise from both size effects and electron-transfer effects. These size and transfer effects can be related to increased propensity for oxidation of the metallic deposit, as well as to various changes in electrochemical performance such as durability or required overpotential for a given reaction. A review of our recent work on layer-by-layer near-surface effects of atomic and electronic structure on catalytically relevant properties will be presented. We use electrochemical atomic layer deposition for layer-by-layer growth of platinum group metals (PGM), and measure the evolution of electronic and atomic structure using synchrotron-based X-ray Photoelectron Spectroscopy (XPS) and X-ray absorption spectroscopy. XPS using a tunable energy synchrotron X-ray source allows us to profile the transitions in the electronic structure from the surface down to the adlayer/support interface and beyond. In addition to depth profile studies of these layered metal architectures, the effects of thermally and electrochemically activated near-surface alloying in the PMG systems will be presented here. We observe undulations of near-surface electronic structure brought on by the low dimensionality of the PMG adlayer as well as the adlayer-support interactions, effects that can explain the resulting surface.
Modified Electrodes with Adsorbed Porphine Complexes on Modified Covalent Surfaces. Effect of the Covalent Bond on the Electrocatalytic Activity
Authors: Ramirez Galo , Canales Camila
Published: February 2020

In this work, glassy carbon (GC) electrodes were modified with different species covalently bonded to the surface, being allowed to act as bridge molecules, for the posterior modification by adsorption of the azamacrocyclic complexes of transition metals. The bridge molecules that were studied were isonicotinic acid (GC-AL), 4-aminobenzoic acid (GC-PABA), 4-aminopyridin (GC-4AP) and the glassy carbon own functional groups obtained from its oxidation (GC-Ox). The modification was done through different methods that included the controlled-potential electrolysis in presence of the species, and electrochemical in-situ generation of the specie that was able for bonding.

Once this procedure was probed versus the redox couple Fe(CN)6
3-/ Fe(CN)6
2-, its electrocatalytic activity was studied versus oxygen reduction. It was found that the more active system, in comparison to the bare GC electrode, was the one that was obtained with the own GC functional groups (GC-Ox) (Figure 1A). Then, after the electrode was modified, the physical adsorption of the octaethyl porphine of M(II) complex (Figure 1B) was done, where M=Co, Cu, Zn, Ru and Fe. The modification process with the porphine was done by adsorption of monomer multilayers and by reflux, in order to obtain ordered systems with directional complex columns due to the different bridge molecules, as said before. It was found that the activity versus oxygen electroreduction was notoriously increased when the Co(II) complex is used, which shows a potential shift and a current increment. The figure 1C shows this behavior for the system modified with GC-Ox, as a covalent electrode. In this case, the Fe complex gets a better response in terms of current, but the potential shift is better accomplished with the Co(II) complex (GC-Ox-Co).

Acknowledgements: To Fondecyt project Nº 1120049
Preparation and Characterization Nanocomposites Based on Conducting Polymers and Functionalized Carbon Nanotubes with Different Dopants
Authors: Branzoi Florina , Branzoi Viorel , Pahom Zoia
Published: February 2020

Conducting polymers can be doped and dedoped rapidly to high charge density and as a result are potential active materials for use in various electrochemical applications. Thus an important application is the fabrication of modified electrodes. For this reason, the nanocomposite materials based on the functionalized carbon nanotubes, conducing polymers and different anionic dopants (sodium dodecyl sulphate -SDS, sodium dodecylbenzenesulfonate - SDBS) were grown electrochemically onto a platinum substrate from an aqueous solution of 0.1M LiClO4, functionalized carbon nanotubes, surfactants and the corresponding monomer (3,4 ethylen-dioxythiophene). All the obtained composites showed improved mechanical integrity, higher electronic and ionic conductivity and exhibited larger electrode specific capacitance than the polymer alone. The negatively charged FCNTs served as anionic dopant during the electropolymerization to synthesize PEDOT/FCNTs composite films. The synthetic, morphological and electrochemical properties of nanocomposite materials type PEDOT / FCNTs / surfactants were compared. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry and scanning electron microscopy (SEM) were used to investigate the electrochemical properties of the composite films.

The specific electrochemical capacitance of the composite films is a significantly greater value than that for pure polymer films prepared similarly. Using these composite films, the modified electrodes with improved properties were obtained.
Lithium Based Ionogel as Solid State Electrolyte: Dynamics of Confined Ionic Liquid, a Neutron Diffusion Study
Authors: Cerclier Carole , Zanotti Jean-Marc , Embs Jan , Le Bideau Jean
Published: February 2020

Ionic liquids (ILs) have been the focus of a rapidly growing number of studies in materials science since early 2000’s. Their liquid state is advantageous for their properties but often prevents their applications in devices which most often need solid state shaping. Thus, several approaches to get round this drawback are under investigation. Polymerizing the IL, grafting any of its ions onto a substrate, making physical gels … We have focused our work on confining IL in host matrices, resulting in solid materials, as well as leaving the dynamics features of the liquid state. The host matrix can be either fully inorganic, mixed polymeric and inorganic or fully polymeric. In each case, there is a continuous silica-to-IL interface, where silica has been obtained through sol-gel route. The solid obtained is thus endowed with properties of the choosen IL simultaneously with those of a robust host backbone including a silica interface.

The resulting ionogels, fully inorganic, mixed polymeric and inorganic or fully polymeric, are showing striking properties. The synergetic associations allow most often to lower the melting point of IL as well as to increase the ionic transport. It will be shown that the continuous interface and the confinement at nanoscale are modifying advantageously intensive properties of ILs. The conclusions are supported by results of studies with local probes (NMR, QENS, relaxometry, PGSE) and macroscopic measurements (CIS, BDS, DSC, IR) which show complementary information on chemistry, texture and physics (charge transport, dynamics, transmittance, dielectric …).

Among several potential applications, we are focusing on supercaps, lithium batteries, electrochromic and photochromic devices. The macroscopic observation of the properties of these solid devices shows either equal or superior properties as referred to genuine ILs.
Double Salt Ionic Liquids Prepared by Mixing Partially Miscible Ionic Liquids: Tuning the Solubility of Lipophilic Molecules
Authors: Wang Hui , Pereira Jorge , Myerson Allan , Rogers Robin Don
Published: February 2020

Over the past twenty years, ionic liquids (ILs) have received much attention as interesting new solvents which can offer unique properties often unavailable in traditional molecular solvents. Now, “IL/IL mixtures”, prepared by mixing two or more ILs, and their specific physicochemical properties are attracting increasing interest from the scientific community. It is surprising that quite a few papers describing the properties of “IL/IL mixtures” tend to view these systems simply as mixtures rather than unique ionic compositions, even when unexpected properties are observed. We have found that physical properties of “IL/IL mixtures”, such as viscosity, density, excess molar volume, etc., seem to be mainly controlled by the composition and the intrinsic ion interactions, and thus any ideal or non-ideal behavior depends on the particular property studied, the nature of the ions, the abundance of each ion, as well as competitive interactions (e.g., Coulombic interactions and hydrogen bonding) between the ions. These “IL/IL mixtures” can be considered to be liquid analogs of double salts, salts containing more than one cation or anion, which are known to exhibit unexpected associations that yield non-ideal properties. Based on this similarity, we propose that two or more ILs, when mixed homogeneously, should be viewed as “Double Salt Ionic Liquids” (DSILs) and should be defined by the specific ion combinations present, rather than considered as only a “mixture” of two ILs. Solubility studies with molecular solvents and active pharmaceutical ingredients in DSILs demonstrate that solubility of selected solutes (protic, aprotic, acid, base, etc.) in the DSILs can be finely tuned via changes in the ion compositions. These studies support the concept that each DSIL is a unique ionic fluid that is able to provide tunable solvent property sets derived from the ions present and that these properties can be controlled by choosing the nature and the abundance of the ions.
Electrochemical Studies of Imidazolium Carboxylate Adducts in a Room-Temperature Ionic Liquid
Authors: Cheek Graham T. , Roeper Donald F. , Pearson Wayne , O'Grady William E.
Published: February 2020

Introduction

Recent interest in carbon dioxide sequestration has prompted much research into ways of forming compounds from CO2 (1). One possible route for this process is reaction of CO2 with carbenes, which can be formed from the reduction of imidazolium cations (2). This paper reports recent results in this regard, carried out in a room-temperature ionic liquid.

Experimental

All electrochemical experiments were carried out in a Vacuum Atmospheres glovebox. Cyclic voltammograms were obtained on a PAR 283 potentiostat using PowerSuite software. Potentials are reported with respect to an Ag/AgCl reference electrode. X-Ray diffraction structure determinations were run on a Bruker AXS Kappa APEX-II. 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMI BF4 ) and 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate (BMPY TfO) were prepared by literature methods (3, 4).

Results and Discussion

The electrochemical properties of EMI BF4 were investigated in the room-temperature ionic liquid BMPY TfO. The EMI cation undergoes reduction at -2.2 V vs Ag/AgCl, followed by an oxidation process at -0.40 V on the reverse sweep. Introduction of CO2 into the solution results in a rather large increase in the reduction process at -0.40 V, suggesting that the EMI+ reduction product can interact with the added CO2 in a catalytic process. For comparison, CO2 reduction by itself in BMPY TfO occurs at -2.8V, so that the observed current increase at -0.40 V for the EMI+ / CO2 combination is not due to direct reduction of CO2. In order to identify the reaction products from the EMI+ / CO2 interaction, voltammograms of the imidazolium – carboxylate adducts, 1,3-dimethylimidazolium-2-carboxylate and 1,3-dimethylimidazolium-4-carboxylate, were run. The adduct structures were confirmed by X-ray structure determinations. The reduction of these adducts occurs at -2.6 V and -2.4 V, respectively, with an oxidation process at -0.35 V on the return sweep. These results support the formation of CO2 adducts with the EMI+ reduction product, probably a carbene.

References

(1) “Electrochemical CO2 Reduction on Metal Electrodes,” Y. Hori, Modern Aspects of Electrochemistry, Number 42, edited by C. Vayenas et al., Springer, New York, (2008).

(2) A. B. Bocarsly, Q. D. Gibson, A. J. Morris, R. P. L’Esperance, Z. M. Detweiler, P. S. Lakkaraju, E. L. Zeitler, and T. W. Shaw, ACS Catalysis, 2, 1684 (2012).

(3) S. Park and R. J. Kazlauskas, J. Org. Chem. 66, 8395 (2001).

(4) L. Crowhurst, N. L. Lancaster, J. M. P. Arlandis, and T. Welton, J. Am. Chem. Soc.,
126, 11549 (2004).
Electrodeposition of Palladium in 1-Butyl-3-Methylimidazolium Chloride Ionic Liquid
Authors: Shrestha Sujan , Gjoka Eriugen , Biddinger Elizabeth J.
Published: February 2020

Ionic liquids (ILs) have superior electrochemical properties that make them ideal for electrodeposition (1, 2). These properties include higher conductivity than non-aqueous solvents, wide electrochemical window and high solubility of metal salts. Moreover, complications due to air or water reaction at a metal/IL interface could be readily managed in air and water stable ILs (2).

Electrodeposition of a metal is strongly affected by IL properties such as viscosity and conductivity which are depended upon its cations and anions (3). Cations also adsorb on the electrode surface and influence double layer structure at reduction potentials, while anions control the metal speciation (2). In addition, concentration of the dissolved metal ion affect the electrodeposition by changing the properties of ionic liquid and affecting the interactions at the metal/IL interface (2). Study of these phenomena on electrodeposition is limited (2).

In this work, electrodeposition of Pd ions in 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) and 1-butyl-3-methylimidazolium dicyanamide ([Bmim][DCA]) was investigated for fission palladium recovery application. Deposition properties are strongly depended upon the IL selected. For example, Figure 1a shows a Ni flag electrode immediately after Pd electrodeposition in [Bmim][DCA] at -0.9 V vs Fc/Fc+ for 2 h at room temperature. On the Ni substrate, black deposits of Pd particles were found which was washed away upon insertion into methanol (Figure 1b) suggesting that the Pd particles formed were loosely attached onto the Ni surface. More studies on the effect of the ILs and substrate on the electrodeposition of Pd will be presented.

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

References

1. S. Z. E. Abedin, M. Polleth, S. A. Meiss, J. Janek and F. Endres, Green Chemistry, 9, 549 (2007).

2. A. P. Abbott and K. J. McKenzie, Physical Chemistry Chemical Physics, 8, 4265 (2006).

3. M. Galiński, A. Lewandowski and I. Stępniak, Electrochimica Acta, 51, 5567 (2006).
Effects of Process Conditions on the Fluidised Cathode Electrochemical Reduction of Tungsten Oxide in Molten LiCl-KCl Eutectic
Authors: Abdulaziz Rema , Brown Leon D , Inman Douglas , Simons Stefaan J. R. , Shearing Paul R , Brett Dan J. L.
Published: February 2020

The direct electrochemical reduction of titanium oxide to titanium metal has been evinced by the FFC Cambridge process. [1] Numerous studies have been carried out to assess the performance and applicability of the process to the reduction of titanium, other refractory metals and metal alloys. However, there are some limitations to the FFC Cambridge process. For example, at least in the case of titanium, the current efficiency is quite low (10-40% to achieve 0.3% oxygen content in the final titanium product). [2]

There are two main reasons that hinder the reduction process: oxide product build-up in the electrolyte close to the surface and within the pores of the precursor, resulting in anomalous electro-migration of the oxygen vacancies, creating a barrier to the reduction process; and limited diffusion of the electrolyte within the precursor porous matrix. [3]

Thus, innovative new designs of the process are needed. The fluidised cathode process [4] offers a solution to these problems. Figure 1 is a schematic of the electrolytic cell used. The process is potentially applicable to the range of metals and molten salts systems and has been exemplified for the reduction of WO3 in LiCl-KCl eutectic. However, there is still much to be investigated to establish a full understanding and optimise the process. This paper discusses experimental findings of the effects the fluidisation rate and the void fraction have on the fluidised cathode applied to the Li-K-W-O-Cl system.

Figure 2. is a chronoamperogram of the process at different rates of fluidisation (argon flow rate). Coulometric analyses have been carried out to assert the extent of its effect. Electrochemical impedance spectroscopy (EIS) studies have also been conducted to establish the effects of the fluidisation rate and the void fraction (concentration of WO3 in the melt) on the diffusion properties between the working and counter electrodes.

Applications to more technologically relevant systems such as the electrochemical reduction of uranium oxide to uranium, as being investigated in the EPSRC REFINE consortium programme, are also discussed.

References:

[1] G. Z. Chen, D. J. Fray and T. W. Farthing, Nature, 407(6802), 361 (2000).

[2] C. Schwandt, D. T. L. Alexander and D. J. Fray, Electrochim. Acta, 54(14), 3819 (2009).

[3] E. Krasicka-Cydzik, ECS Trans., 50(11), 39 (2013).

[4] R. Abdulaziz, L. D. Brown, D. Inman, S. Simons, P. R. Shearing and D. J. L. Brett, Electrochem. Commun., 41(0), 44 (2014).
Carbon Fibers and Nanotubes as a Product of Interaction between Silicon Carbide and Carbonate Melt
Authors: Devyatkin Sergei Vladimirovich
Published: February 2020

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

I. 3Si + 2Na2CO3 = 2C + 4Na + 3SiO2

ΔGo
1023 K = -473 kJ

II. 3SiC + 2Na2CO3 = 5C + 4Na + 3SiO2

ΔGo
1023 K = -277 kJ

III. 3TiC + 2Na2CO3 = 5C + 4Na + 3TiO2

ΔGo
1023 K = -54 kJ

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

References

1. R. E. Dial, G.E. Mangsen, Corrosion,
17, 35t
(1961).

2. R.E. Tressler, M.D. Meiser, T. Yonushonis, J. Am. Ceram. Soc.,
59, 278 (1976).

Fig. 1. SEM micrograph of SiC (F14) powder after 2 hours interaction with carbonate melts at 7500C .
Use of Fluorescence Imaging and Ionic Liquids in the Study of Carbon, Clay, and Cellulose Based-Nanomaterials
Authors: Gilman Jeffrey W.
Published: February 2020

Some of the most critical issues facing the nanocomposites community include the need for multi-scale imaging of the hierarchical structure, effective methods for controlling nanoparticle surface-energy and chemistry, and new processing methods for preparing novel nanoparticles. Over the last decade we have employed ionic liquids and fluorescence microscopy to address these challenges. This presentation will discuss how the combination of ionic liquid modified materials and new measurement methods work together synergistically. Examples will include: fluorescent microscopy imaging of imidazolium- Nile blue- montmorillonite polymer nanocomposites, carbon nanotube polymer nanocomposites prepared using imidazolium ILs, Főrster resonance energy transfer (FRET) imaging of the interface in cellulose nanofibers composites, IL processing to isolate cellulose nanofibers from biomass, and surface modification of cellulose nanofibers using IL.
Natural Fiber Welded Composite Yarns
Authors: Brown E. Kathryn , Durkin David P. , Fox Eric T. , Haverhals Luke M. , Sweely Kurt D. , De Long Hugh C. , Trulove Paul C.
Published: February 2020

In this application, an ionic liquid (IL), specifically 1-ethyl-3-methylmidazolium acetate (EMIAc), well known for its ability to dissolve a variety of biopolymers1-3, is used in conjunction with molecular co-solvents to prepare biopolymer composite yarns by a process we call natural fiber welding (NFW). NFW uses controlled amounts of IL and a molecular co-solvent to swell and mobilize portions of the biopolymer substrate. By carefully selecting factors controlling NFW such as time, temperature and solvent system composition, partial dissolution occurs, mobilizing and redistributing only a small portion of the natural fibers and leaving much of the underlying substrate intact.4-7 This results in fibers with a shell of dissolved polymer, permanently adhered and hydrogen bonded to both the outer diameter of the fiber and (depending on the extent of welding) to the surface of adjacent fibers.

With the addition of a small amount of biopolymer into the IL solution, a NFW composite yarn can be created with the pre-dissolved biopolymer acting as an additional binder. Different combinations of biopolymer binder and substrate take advantage of the functional and structural benefits of both biopolymers. Binder can also be used to facilitate incorporation of functional materials (e.g., magnetic, electronic, photonic) into the yarn fiber matrix.

References

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

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

Xie, H.; Zhang, S.; Li, S. Green Chem.
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Haverhals, L. M.; Reichert, W. M.; De Long, H. C.; Trulove, P. C. Cellulose, 2010, 2985, 425.

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

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

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

Traditionally, ionic liquids are divided into two classes. The first ionic liquid, [C2H5NH3][NO3] (melting point13–14 ᵒC), was synthesized by Walden via the neutralization of ethylamine with concentrated HNO3, as reported in 1914.1 Because a proton-transfer reaction between an organic base and an acid is used during synthesis, this first class of ionic liquids is classified as protic ionic liquids. In 1951, Hurley and Wier reported new ionic liquids prepared by mixing alkylpyridinium chlorides with AlCl3.2 This work marked the genesis of the second class of ionic liquids, i.e., aprotic ionic liquids. The cations of the aprotic ionic liquids are derived from the alkyl–cation-transfer reaction between an organic base and an alkyl halide. Since then, many ionic liquids composed of various organic cations and inorganic or organic anions have been developed.3,4 Because there are large varieties of cations and anions available, their combination amounts to numerous potential ionic liquids. We have recently developed a third class of ionic liquids.5-7 The essence of our strategy is to synthesize the cations of ionic liquids via the metal–ion-transfer reaction between a neutral organic ligand and an inorganic salt. The key feature of this class of ionic liquids is that their cations consist of metal–ion complexes. These metal-containing ionic liquids provide not only ideal ionic environments, but also liquid inorganic precursors for electroplating of metals, gas separation, and synthesis of inorganic materials. The recent advances in this class of ionic liquids will be discussed.

Acknowledgment: This research was sponsored by the SERDP program.

(1) Walden, P. Bull. Acad. Imp. Sci.
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(2) Hurley, F. H.; Wier, T. P. Journal of the Electrochemical Society
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(3) Welton, T. Chem. Rev.
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(4) Wasserscheid, P.; Keim, W. Angew. Chem.-Int. Edit.
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(5) Huang, J. F.; Luo, H. M.; Dai, S. Journal of the Electrochemical Society
2006, 153, J9.

(6) Zhu, H. G.; Huang, J. F.; Pan, Z. W.; Dai, S. Chem. Mat.
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(7) Ma, Z.; Yu, J. H.; Dai, S. Adv. Mater.
2010, 22, 261.
Novel Pathways for Improving the ORR Rate
Authors: Snyder Joshua David , Kang Yijin , Strmcnik Dusan , Li Dongguo , Markovic Nenad M , Stamenkovic Vojislav R
Published: February 2020

Technologies such as fuel cells and lithium-air batteries rely on electrochemical processes that need to provide satisfactory energy density; however, a major challenge lies in the insufficient activity and durability of materials that are currently employed as cathode catalysts for electrochemical reduction of oxygen. These limitations inevitably lead to a lower operating efficiency of the devices, which highlights the need for development of more active and durable oxygen reduction reaction (ORR) catalysts. Consequently, the majority of research efforts are placed on the catalyst design and synthesis aiming to improve their efficiency. It has been found that properties such as surface structure, surface and subsurface composition associated with electronic properties have distinguished roles in determining functional properties of electrocatalysts 1. In this report the material-by-design-approach, would be used to demonstrate how the knowledge obtained from the well-defined surfaces can be employed to create tailor-made practical catalysts with advanced catalytic properties 2. Considering the fuel cells, most of the research is centered on platinum, the best monometallic catalyst for the ORR. However, multimetallic systems could provide additional benefits by bringing together highly diverse constituents to alter and tune both catalytic activity and durability of the catalysts 3.

In addition to the catalyst's material it is of paramount importance to emphasize the role of liquid phase which is influencing on the overall properties of an electrified interface. Molecular species from employed electrolyte and the nature of their interaction with the catalyst surface can be also used in tuning the catalytic performance. More recently, it was also demonstrated that molecular patterning could be used as a tool that can induce selectivity of the electrocatalyst 4.

[1] Stamenkovic et al. Science315 (2007) 493.

[2] Stamenkovic et al. Nature Materials6 (2007) 241.

[3] Wang et al. Nano Letters11 (2011)919.

[4] Genorio et al. Nature Materials 9 (2010) 998.
A Formic Acid Air-Breathing Microfluidic Fuel Cell Feeding with a Single Stream
Authors: Ortiz-Ortega Euth , Cuevas-Muñiz Francisco Mherande , Armenta-González Angélica Janeth , Guerra-Balcázar Minerva , Ledesma-García Janet , Arriaga Luis Gerardo
Published: February 2020

In the search of improve the performance of the microfluidic fuel cell, air-breathing microfluidic fuel cell (ABµFC) has emerged as interesting solution; this fuel cell increase the quantity of oxygen reaching the cathode taking the oxygen of the air through a porous material increasing the global performance of the fuel cell. Also, in literature has been reported the use of one stream of fuel-oxygen to reduce the complexity of the fuel cell, allowing simpler and low-cost designs. In this work is proposed the construction and evaluation of an operated with only one stream of formic acid in acid media. The ABµFC is operated with one feed flow contents 0.1, 0.5 and 1 M formic acid achieving similar power density values using commercial Pt/C (near to 80%) and AuPd/C (near to 99%) as cathodes in comparison with the counterparts feeding with two streams (fuel and electrolyte). These results are promising towards the development of simpler designs of ABµFC.
Highly Tunable and Ordered Graphene-Oxide-Based Materials for Energy Applications
Authors: Martinez Ulises , Mohite Aditya , Purdy Geraldine M , Dattelbaum Andrew M , Zelenay Piotr , Gupta Gautam
Published: February 2020

Carbon materials are an integral part of devices including fuel cells, super-capacitors, and batteries. Current technologies are marred with issues such as long-term durability under high potentials (e.g., fuel cells), low energy/power density (super capacitors), and metal intercalation issues (batteries). State-of-the-art devices have typically been synthesized from highly heterogeneous precursors and amorphous carbon materials. Materials based on graphene and graphene-oxide (GO) are more homogeneous and possess properties, such as good chemical stability, excellent conductivity, and more importantly, can be functionalized in a controlled manner. These unique properties have led to explosion in research in areas of graphitic materials as catalyst support/material for oxygen reduction reaction (ORR) and high energy density thin film super capacitors.

In this study, we report the synthesis of highly structured GO based materials prepared using Hummers method. We specifically target the control of functional groups and d-spacing of GO materials using drying and solvent treatments. XPS, FTIR and XRD studies were used to unravel the structure-function correlation of the resulting materials. The synthesized graphene oxide structures were further subjected to reduction and doping in different conditions to obtain an optimum energy storage/support material. Although most reduced materials possess similar structural properties, they have a variable electrochemical performance and stability. In this study we obtain a fundamental understanding of the effect of pre-treatment on the structure and function of reduced materials.

We specifically study these materials for oxygen reduction reaction and super capacitors. In a 0.5 M H2SO4 electrolyte, a shift in half wave potential and decrease in peroxide production is obtained depending upon the graphene oxide treatment. These catalyst materials perform well in an alkaline electrolyte as well. These catalyst systems are highly durable and a drop of less than 30 mV drop was obtained over 2000 cycles in acid electrolyte in presence of oxygen indicating the role of high graphitic content in providing stability. Furthermore, we identify that the pyridinic nitrogen content is important for high electrochemical activity. We also demonstrate high power density super capacitors obtained using similar pretreatments.

Acknowledgment

Financial support from the Los Alamos National Laboratory Laboratory-Directed Research and Development (LDRD) Program is gratefully acknowledged.
Systems Electrochemistry
Authors: Varela Hamilton , Kiss Istvan Z
Published: February 2020

Beyond the Cartesian framework, emergent processes in many chemical, physical, and biological systems exemplify the maxim ‘the whole is more than the sum of its parts’. An electrochemical reaction provides a prototype example of a complex system where interactions of chemical reactions and physical processes (mass transfer, electrostatics) produce non-trivial, emergent temporal and spatial dependences of reaction rates. The integrative experimental and modeling techniques are the common denominators in Systems Electrochemistry: the main objective is to advance the understanding of emergent properties of electrochemical systems in which many variables are handled simultaneously. A wide range of, typically far-from-equilibrium, systems are considered in electrocatalysis, corrosion, bioelectrochemistry, electrodeposition, batteries, fuel cells, and semiconductor systems. Concrete examples include multistability, periodic and chaotic oscillations, and pattern formation in electrochemical reactions, whole-cell bioelectrochemistry, stability of single and cascaded fuel cells, reaction dynamics coupled with mass transfer, and stochastic corrosion phenomena. System Electrochemistry encompasses thus many electrochemical systems in a transdisciplinary agenda that aims to bring together experts from various fields who use mathematical and experimental approaches for the characterization of dynamical responses in temporal and spatial domains. The adoption of Systems approaches in various fields will expand considerably the understanding of complex electrochemical processes. In this introductory address of the Systems Electrochemistry symposium, we discuss some of these aspects, illustrate examples, and suggest future directions.