bluuebunny/crossref_metadata_2025_split huggingface dataset:
Foreign Metal-Ions Tuned Electrochemical Processes in Ionic Liquids for Bulk-Metal Surface Treatment
Authors: Jiang Junhua , Kerr Matthew 
Published: February 2020

Electrochemical surface treatment of metals offers a cost-effective and convenient approach to create highly-functional surfaces and produce nanostructured materials, for a wide range of potential applications such as electrochemical sensing, energy storage, and manufacturing. Different from ordinary electrochemical surface-treatment technologies, our work has investigated a green ionic-liquid based electrochemical process which can be tuned by introducing foreign metal ions into the ionic liquid for the purpose mentioned above. In the electrochemical process, the foreign metal ions deposit onto a bulk metal in an electrodeposition mode, and are regenerated in a subsequent electro-dissolution mode. Their in-situ electrochemical deposition-dissolution on the bulk metal can be tuned by controlling electrochemical driving forces such as currents or overpotentials and the composition of the ionic-liquid bath. The structures of the treated bulk metal may be strongly dependent upon the interactions between the bulk metal and the foreign metal electrodeposited, and their electrochemical activities in the ionic liquid. Figure 1 shows three distinct nanostructures of gold surfaces treated using three different foreign metal ions added to an ionic liquid bath, suggesting that it is possible to not only prepare highly actively gold electrodes for sensor and catalyst applications, but also produce nanostructured materials such as nanoporous and nanospherical gold powder.
In this presentation, we will introduce our green-chemistry method tuned by the electrochemical deposition and dissolution of foreign metal ions in ionic liquids, as well as the characterization of resulting surface nanostructures and their applications to electrochemical sensing and energy storage.

Figure 1
Electrochemical Deposition of Tantalum from Ionic Liquids
Authors: Engemann Thomas , Ispas Adriana , Borisenko Natalia , Frankemoelle Lennart , Becker Julian , Bund Andreas , Hunt Patricia A 
Published: February 2020

Tantalum belongs to a class of metals called refractory metals (Niobium, Molybdenum, Tantalum, Tungsten and Rhenium) which are exceptionally resistant to heat and mechanical wear. Due to their tendency to form stable and dense oxide layers, these metals also possess a high resistance towards chemically agressive media. Therefore these metals can be used as protective coatings to build corrosion resistant parts, such as thermowells and valve bodies or for the production of special vacuum furnace components.[1]

The electrochemical deposition of refractory metals is a cost-efficient method to coat materials of complex geometries. The negative reduction potential of Ta makes it impossible to use aqueous solutions. Thus ionic liquids (ILs), with an electrochemical window of 5 to 6 V, are promising alternative solvents and have been intensively used in different research fields of electrochemistry during the last years.[2]

We have investigated the electrodeposition of Ta using different Ta halides (TaX5, X=F, Cl or Br) and different pyrrolidinium based ILs (1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [BMP][TFSI] and 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, [BMP][OTf]). We could show that the combination of the precursor and the IL has a strong influence on the electrodeposition process of Ta. Furthermore using IR spectroscopy we found significant differences in the spectra of the different electrolytes which we correlated with results from computated spectra using Density Functional Theory (DFT). The aim of this combined IR/DFT approach is to identify the formed species in our electrolytes.
We will present these data together with experimental results from investigations on the reduction mechanism using different electrochemical in-situ techniques (Differential Pulse Voltammetry, Rotating Ring Disk Electrode, Electrochemical Quartz Micro Balance) to show the influence of precursor-IL interaction on the electrodeposition process of Ta from ILs.

Literature

1 F. Endres, A.P. Abbott, D. MacFarlane, Electrodeposition from Ionic Liquids, Wiley-VCH, Weinheim, 2008.
2 A. Ispas, B. Adolphi, A. Bund, F. Endres, Phys. Chem. Chem. Phys., 12 (2010) 1793-1803.
Modeling of Two-Phase Flow during the Electrolysis of Water in an Electrochemical Reactor in Serpentine Array
Authors: Castañeda Ulloa Locksley Fabiàn , Nava José Luis 
Published: February 2020

Currently the characterization of the reaction environment within any filter-press type reactor through computational modeling is very important in the design to obtain an effective flow dispersion and therefore a uniform current and potential distribution [1]. During two-phase electrolysis such as chlorine production, water electrolysis, alumina reduction, electrocoagulation, and many other electrochemical processes appears gas release on the electrodes, H2 or O2 (bubbles), which imply a quite important electrical properties and electrochemical processes disturbance [2]. The bubbles are motion sources for the flow cells, and then hydrodynamic properties are strongly coupled with species transport and electrical performances, hence, the bubbles presence modifies the electrolysis cell performance and principally the hydrodynamics and current density distribution [3]. Therefore, this works deals with the two-phase modeling (H2O-H2) flow inside of a pre-pilot-scale continuous reactor with a stack of six cells in a serpentine array by solving the Reynolds-averaged Navier-Stokes (RANS) equations with κ-ε turbulence model (Euler-Euler approach). The hydrogen evolution reaction comes from the electrolysis of water. The electrodes were plates of aluminum, typically used in electrocoagulation processes. In order to perform a more complete flow pattern characterization, residence time distribution (RTD) studies were carried out to validate the CFD simulations in biphasic flow. The RTD simulations were calculated solving the averaged diffusion-convection equation. Close agreement between experimental and theoretical RTD simulations were attained. Finally, simulations of distribution of current and potential density distributions inside the pre-pilot-scale continuous reactor were carried out using the Bruggeman relation, observing the effect of bubble production on the distribution of potential along the electrodes.
References
[1] F.F. Rivera, C. Ponce de Leon, F.C. Walsh, J.L. Nava, The reaction environment in a filter-press laboratory reactor: the FM01-LC flow cell, Electrochim. Acta 161 (2015) 436e452.
[2] Lokmane Abdelouahed, Rainier Hreiz, Souhila Poncin, Gérard Valentin, Francois Lapicque, Hydrodynamics of gas bubbles in the gap of lantern blade electrodes without forced flow of electrolyte: Experiments and CFD modelling, Chem. Eng. Sci. 111 (2014) 255–265.
[3] Mandin P., Hamburger J., Bessou S., Picard G. Modelling and calculation of the current density distribution evolution at vertical gas-evolving electrodes, Electrochem Acta. 51 (2005) 1140-1156.
Electrochemical Selectivity for Metals in Molten Sulfides
Authors: Wagner Mary-Elizabeth , Allanore Antoine 
Published: February 2020

Molten sulfides show promise as an alternative electrolyte for production of metals such as copper and silver. They provide a means to sidestep the current emissions- and waste- heavy processes used both in primary (e.g. from ore) and secondary (e.g. recycled product) streams by direct reduction of a metal's sulfide form, such as Cu2S, to produce metal and sulfur. Experiments with molten sulfide electrolytes have shown high efficiency in the reduction of copper sulfides and iron sulfides to their metals. Data have also demonstrated high solubility of precious metals silver and gold, and stable electrochemical signals during reduction, evidence for a viable and streamlined method of precious metal refining and recycling.
The current work focuses on predicting which metal, and of what purity, is reduced from the electrolyte. Because the standard-state reduction potentials of copper and iron sulfides are very close to each other (less than 100mv), and because the reduction potentials of silver and gold sulfides are also hypothesized to be close in value with each other, there is a possibility of co-deposition occurring, compromising the purity of the final metal product. By carefully tailoring the activities of the electrolyte species and cathode products, it is possible to bias the reduction reaction towards one species over another. Therefore, the thermodynamics of both the electrolyte and metal product should be very well defined. This talk will discuss experiments in determining metal/sulfide equilibria and how that equilibrium relates to efforts in modeling the cathode product.
Electrosynthesis of Hydrogen Peroxide in a Novel Flow-through Electrochemical Reactor with in Situ generated Oxygen
Authors: Cornejo Oscar Miguel , Nava José Luis 
Published: February 2020

Most of electrochemical advanced oxidation processes (EAOP´s) such as the electroFenton (EF), photo electroFenton (PEF), solar photo electroFenton (SPEF) and electro-peroxone (E-peroxone) processes use hydrogen peroxide (H2O2) as its core reactant due to its possibility to react with some catalysts (Fe2+, O3) yielding high oxidant hydroxyl radicals to be used in the degradation of persistent organic pollutants [1]. Carbonaceous materials like carbon felt, carbon cloth and reticulated vitreous carbon (RVC) are the most used because of its capability to accumulate H2O2 [2,3]. The use of these materials is often in gas diffusion electrodes which are based in the injection of air from an external source to an air chamber located behind the electrode allowing the dispersion of the gas inside the electrode promoting the oxygen reduction [3]. This work deals with the in situ electrosynthesis of H2O2 in a flow through reactor using RVC as cathode material and Ti|Ir-Ta oxides expanded mesh as anode to improve the oxygen evolution reaction with subsequent reduction of O2 on the RVC to yield H2O2. The electrochemical cell consists of a flow channel where the electrodes are placed along its length, allowing the electrolyte to flow through them forcing the transport of oxygen bubbles inside the porous carbon material for its reduction to H2O2.
[1] Sirés I., Brillas., E. Remediation of water pollution caused by pharmaceutical residues sed on electrochemical separation and degradation technologies: A review. Environmental International, 40 (2018) 212-229.
[2] Coria G., Pérez T., Sirés I., Nava J.L., Mass transport studies during dissolved oxygen reduction to hydrogen peroxide in a filter-press electrolyzer using graphite felt, reticulated vitreous carbon and boron-doped diamond as cathodes. Journal of Electroanalytical Chemistry, 757 (2015) 225-229.
[3] Pérez T., Coria G., Sirés I., Nava J.L., Uribe A.R., Electrosynthesis of hydrogen peroxide in a filter-press flow cell using graphite felt as air-diffusion cathode. Journal of Electroanalytical Chemistry, 812 (2018) 54-58.
(Invited) Molecular Engineering of Redox-Active Electrodes for Selective Ion Separations and Process Intensification
Authors: Su Xiao 
Published: February 2020

Molecular level design is crucial for the development of new, more efficient electrochemical interfaces for a wide range of industrial and environmental applications. In particular, selective separations remain one of the most important processes in the chemical and biochemical industries, and are crucial for water purification and environmental remediation. Thermal and pressure-based systems can incur high energetic costs, while adsorption technologies often require harmful solvents and regenerants. Despite the great interest in electrochemical systems for energy storage and electrocatalysis, a lack of molecular selectivity and the relatively narrow range of materials chemistry have limited their applications in separations science.
Redox-functionalized electrode materials offer an attractive platform for performing selective electrochemical separations. Organometallics, metallopolymers and associated metal-organic complexes offer a wealth in flexibility in terms of metal/ligand design, and control of electronic properties. First, the development of a range of redox-active metallopolymer electrodes is presented, with specific interactions towards micropollutant anions of concern [1-2]. The underlying intermolecular mechanisms are then unraveled by a combination of electronic structure calculations and spectroscopy, and leveraged for fine chemical separations. Second, the capabilities of redox-electrodes are leveraged towards not only selective capture, but tandem environmental transformation of emerging contaminants and heavy metal pollutants, as a pathway towards process intensification through electrification. Chromium and arsenic oxyanions are separated selectively in the presence of excess competing ions, and down to 10-100 ppb concentrations, based on differential charge-transfer interactions [3]. The integrated capture and electro-reduction of chromium was enabled based on a judicious choice of operating voltage windows, and consideration of thermodynamic partitioning of the transition metal elements.
From a fundamental perspective, these concepts point towards an emerging direction in electrochemical interface design – by superimposing properly tuned chemical interactions, we can reach beyond double-layer effects and achieve unprecedented molecular selectivity. From a practical perspective, electrochemically-responsive materials are expected to provide a sustainable and energy-efficient platform for sustainable separations and environmental remediation.

References.

[1] X. Su, et al, “Anion-selective redox electrodes: electrochemically-mediated separation with organometallic interfaces,” Advanced Functional Materials.
2016, 26(20), 3394-3404.

[2] X. Su, et al, “Asymmetric Faradaic systems for selective electrochemical separations,” Energy & Environmental Science, 2017, 10, 1272-1283.

[3] X. Su, et al. “Electrochemically-mediated selective capture of heavy metal oxyanions chromium and arsenic from water,” Nature Communications, 2018, 9, 4701.
How Not to Chase the Wrong Rabbits: Mentorship and Science Lessons from Bob Huggins
Authors: Chan Candace K. 
Published: February 2020

In spring 2008, Bob Huggins presented a talk at the 213th ECS meeting with the provocative title, "Chasing the Wrong Rabbits?", which was accompanied by an even more provocative first line in the body of the abstract: "Several trends in battery materials development activities that are aimed in the wrong directions will be discussed". The context of this talk was specifically related to the use of high voltage cathodes in lithium ion battery systems, the thermodynamics of which can lead to high oxygen activities and ultimately oxygen evolution from the cathode. This conference was memorable, not just for the animated and interesting discussions that followed Bob's talk, nor the fact that Phoenix was unbearably hot at this time, but because it was my first major conference as a Ph.D. student and my introduction to the ECS community under the mentorship of Bob Huggins.
In this talk, thermodynamics considerations as it relates it relates to battery studies as well as other sage advice from Bob Huggins will be discussed along with closing remarks.
Li Plating/Stripping Reactions on Li6.6La3Ta0.4Zr1.6O12
Authors: Motoyama Munekazu , Tanaka Yuki , Yamamoto Takayuki , Iriyama Yasutoshi 
Published: February 2020

Li7La3Zr2O12 (LLZ) is an attractive candidate for oxide solid electrolyte for various Li-metal-based batteries such as all-solid-state-Li battery, Li-S battery, and Li-air battery. This is because LLZ has a high shear modulus and a wide electrochemical stability window and high Li+ conductivity (can be 10−3 S cm−1 depending on dopant element) at room temperature. However, LLZ still cannot perfectly suppress short-circuiting during Li plating/stripping cycles. Although several approaches to suppress the short-circuiting phenomenon have been reported1, why the short-circuiting occurs during Li plating/stripping cycles on LLZ has not essentially been understood. This study applies an in-situ scanning-electron microscope (SEM) observation technique2 to the investigation on the Li plating/stripping reactions on Li6.6La3Zr1.6Ta0.4O12 (LLZT).
A LLZT plate (Toshima Manufacturing Co. Ltd.) with a thickness of 0.5 mm was used as the electrolyte1. A Cu current collector (CC) film was deposited on one side of a LLZT plate by pulsed laser deposition (PLD). A Li film with a thickness of 3 μm and a diameter of 9.0 mm was deposited on the other side of the LLZT plate as the counter electrode by vacuum evaporation. A fabricated Cu/LLZT/Li cell was sandwiched between Cu and brass plates. The Cu plate has a view port in the center. The cell was transferred into the SEM camber without exposure to the air. Li plating/stripping was conducted under galvanostatic conditions at room temperature during the SEM observation.

Figure 1shows the voltage transient during Li plating at 100 uA cm−2 on Cu-coated LLZT. Li does not only nucleate at grain boundaries but also on grain cores. After 450 seconds, the voltage drops to 0 V indicating the occurrence of short-circuiting. This result indicates that only a small number of the nucleation sites exist on LLZT surfaces whereby the local current density is supposed to increase. We will also discuss the detail of short-circuiting mechanism of LLZT.

Acknowledgement

The authors gratefully acknowledge JSPS 17H04894 for the financial supports

References

[1] Motoyama et al., J. Electrochem. Soc.,
162, A7067 (2015).
[2] Yonemoto et al., J. Power Sources,
343, 207 (2017).
Discovery of Novel Oxides and Sulfides Solid State Ionic Conductors for All-Solid-State Li-Ion Batteries
Authors: Xiong Shan , Liu Zhantao , He Xingfeng , Mo Yifei , Chen Hailong 
Published: February 2020

All-solid-state batteries as an emerging electrochemical energy storage technology are attracting extensive attentions, owing to the good safety properties and potentially very high energy density with using Li-metal anode. Solid electrolyte (SE) is the key component in all-solid-state Li-ion batteries and solid state Li ion conductors with high room temperature conductivity, ideal electrochemical stability and good mechanical compatibility are very much desired. Oxides and sulfides based SEs have their own advantages and disadvantages. Oxides can be handled and stored in ambient environment, while their room temperature ionic conductivity is relatively low and the grain boundary is high. Sulfides are commonly not very stable with air and moisture, but they have much higher ionic conductivity, lower grain boundary resistance and favorable mechanical properties for cold processing of solid cells.
Here we report recent progresses in our research group in both oxide and sulfide-based lithium ion conductors. A group of zirconia doped lithium tantalum oxosilicate previously identified through a computation assisted search and screening were successfully synthesized and showed encouraging ionic conductivity of >10-5 S/cm at room temperature. Analysis of electrochemical impedance spectroscopy data and computation predictions indicate that higher conductivity from 10-4 to 10-3 S/cm may be achieved by further optimizations. With using another experiment-based design strategy, a group of lithium chloro-thiophosphate compounds were also experimentally identified assisted by in situ X-ray diffraction investigations and showed high conductivity of >10-4 S/cm. The structure of both sulfide and oxide new compounds were characterized with using synchrotron X-ray diffraction and neutron diffraction. The relationship between their ionic conductivity and structural features, such as unit cell size, diffusion pathway, site occupancy, interstitial sites, etc., were revealed by the characterization and will be discussed in the presentation.
Caption of Figure 1. a) Crystal structure and ionic conductivity of Zr doped LiTaSiO5 with sphene structure. b) Crystal structure of new lithium chloro-thiophosphate

Figure 1
Electrochemical Upgrading of Wastes to Products- Fundamental Studies Using a Combined Experimental and Computational Approach
Authors: Holladay Jamelyn , Lopez Ruiz Juan A , Koh Katherine , Sanyal Udishnu , Gutiérrez Tinoco Oliver Y , Glezakou Vassiliki-Alexandra , Rousseau Roger 
Published: February 2020

In recent years there has been growing interest in using electrochemical methods for hydrogenation of biomass-derived molecules for the formation of biofuels. Conventional hydrogenation processes require moderate temperatures between 433 and 678 K, pressures of 14,000 kPa, and external sources of dihydrogen for the stabilization and formation of biofuels. However, the same reaction can be performed using electrochemical reactors and much lower temperatures and pressures (293 K and 101 kPa) and with no supplied molecular hydrogen.
In this work, we use a combined experimental–theoretical approach to identify atomistic features and parameters that affect the electrochemical hydrogenation (ECH) rates of different biomass organic compounds (such as aldehydes, ketones, and carboxylic acids) under ambient reaction conditions. In particular, we evaluated platinum group metals (PGM) and base-group metals (BGM) for the benzaldehyde ECH and correlated the activity with computationally-derived parameters. We then used these parameters to explain the dependence of molecule functionality on the ECH rates. The experiments were conducted using a continuous flow fixed bed reactor at room temperature and atmospheric pressure in the aqueous phase. We tested 7 metal catalysts with 12 substrates. Classical molecular dynamics simulations were performed on the metal’s most stable surfaces. The GROMACS package(83) was used for all classical molecular dynamics (MD) simulations.
The results, summarized in Figure 1, indicate that the computationally-derived binding energy strongly correlates with the experimentally-derived ECH rates and hydrogen evolution reaction (HER) rates. The results suggest that Pd is the most active material for benzaldehyde ECH because it has an optimal organic reduction potential and binding energy compared to the other metals tested. However, Rh, which has a similar organic reduction potential, it is not active for benzaldehyde ECH due to the strong binding energy and high HER rates. These metrics were also used to evaluate the ECH activity of other biomass-derived molecules and we observed that the experimentally-derived parameters can be used to explain the differences in ECH activity with respect to benzaldehyde. For example, ketones such as acetophenone are not as active for ECH as benzaldehyde because of their binding energy.

Figure 1