bluuebunny/crossref_metadata_2025 huggingface dataset:
Machine Learning for Corrosion Resistance Alloys
Authors: Chien Szu-Chia , Frankel Gerald S. , Windl Wolfgang
Published: February 2020

Determining the ability of corrosion resistance of alloys is of great importance to many applications. While one could call the pitting resistance equivalence number (PREN) a quantitative description of the relative corrosion resistance of stainless steels, it is an empirical value based on the chemical composition of the elements in alloys only, derived by mathematically fitting of experimental alloy data. It provides no scientific insight. In this work we collect a large number of experimental data published in the literature on corrosion of alloys to study the factors that determine the corrosion resistance of materials. A database that includes the alloy composition, electrochemical parameters as well as polarization testing parameters was therefore generated. Machine learning approaches (Lasso and Ridge regression) were used to find the unexpected correlations between aforementioned experimental parameters and the materials' properties. We further use the machine learning to prioritize the features that determine the corrosion resistance and anticipate that this work can be an useful tool for materials design.
Interfacial Treatment of the SiC-SiO2 Interface By Shallow Boron and Barium Multi-Charged Ion Implantation
Authors: Shaim Md Haider , Elsayed-Ali Hani
Published: February 2020

Multicharged ions born and barium ions were used to perform interfacial treatment of the SiC/SiO2 interface. A Q-switched Nd:YAG laser (wavelength λ = 1064 nm, pulse width τ = 7 ns, and fluence F = 135 J/cm2) was used to ablate boron and barium targets to generate multicharged ions. Time-of-flight and three-grid retarding field ion energy analyzer were used to detect the charge state and the ion kinetic energy. Fully stripped boron ions are generated. The ions were deflected by an electrostatic field to separate them from the neutrals. SRIM simulation was used to estimate the ion penetration depth in the SiC substrate. The multicharged ions were used for shallow ion implantation in 4H SiC. The optical bandgap of the 4H SiC was reduced due to boron ion implantation. Several MOSCAP devices were fabricated with combination of boron and barium shallow implantation. High-low C-V measurements were used to characterize the MOSCAPs. Boron implantation affects the flatband voltage significantly, while the effect of barium ion implantation is negligible. Shallow boron implantation in the SiC/SiO2 interface reduces the flatband voltage from 4.5 to 0.04 V.
The Line Roughness Improvement in Self-aligned Multiple Patterning
Authors: Zheng ErHu , Han Qiuhua , Zhang Haiyang
Published: February 2020

Multi-patterning has been widely used in the semiconductor industry to enable the continued scaling requirement such as Fin, Gate, and critical Metal lines. Either Self-aligned Multiple Patterning (SaMP) or Litho-Etch/Litho-Etch (LELE) shows plasma etch become more dominant for the line edge and width roughness (LER/LWR) than single patterning technology [1]. To mitigate the strict line roughness requirements for advanced technology nodes (14nm and below), we proposed and demonstrated a novel nitrogen-based Inductively Coupled Plasma (ICP) treatment and an argon-based Capacitively Coupled Plasma (CCP) treatment on LER/LWR improvement, separately. Both recipes are optimized with an optimal design experiment (ODE) statistical method. The optimal organic mandrel etch recipe can improve the LER of the final pattern to 1.2nm. Furthermore, two effective Si mandrel post etch treatment (PET) methods are investigated: special surface plasma treatment and H2 anneal. The H2 anneal effect was found related to the capping layer, different from former published paper. We also found out the different chemistry in Spacer etch can impact line roughness but trade-off with defect performance. Finally, we achieved a 20% LWR improvement of final pattern in a self-aligned quadruple patterning (SAQP) without any side effect.
Metallic Foams Prepared By Electrolytic Plasma Deposition
Authors: Durut Frédéric , Botrel Ronan , Pinot Julien , Rocher Sandrine , Chicanne Cédric , Theobald Marc , Vignal Vincent
Published: February 2020

In order to study laser-matter interactions on the Megajoule Laser facility, CEA needs to synthesize metallic foams with specific characteristics. The goal is to realize in a millimetric scale, metallic foam samples with a density lower than 10% of the bulk material and structured with a micrometric porosity (< 5 µm). To obtain these specific materials, CEA has developed an innovative process using the Contact Glow Discharge Electrolysis technique (CGDE) to grow metallic foam at a cathode surface. Under specific conditions and when a critical potential is applied, an uniform and stable gaseous envelop is formed around the immersed cathode in the ionic solution. Due to the high electrical field at the electrode surface, channels plasma are formed with the propagation of streamers between the cathode and the liquid surface. When the electrical arcs meet the liquid, metallic cations are reduced to form metallic strands with a bush-like shape. In these conditions, several metallic foams can be obtained (Au, Cu, Pt, Ag, alloys …) with a relative density of 0.5%. All strands of the foam are about 100 nm in diameter and are interconnected together to form porosity about 1 µm. This very fast process allows synthesizing 1 mm thick of foam in less than 10 seconds. This presentation explains the patented process offering a versatile technological way to synthesize microporous and ultra-light metal foams. A new phenomenomenological process is proposed to describe the different steps that take place from plasma formation to nano-foam growth.

The structure (see picture below) of the foams (several m²/g, and ultra-low density ~ 0.5% relative density) could be used for many applications such as battery, fuel cells, hydrogen trapping, catalysis...

Figure 1
Electrodeposition of Porous Fe-Ni-Co Nanowires Using Hydrogen Gas Bubbles
Authors: Li Deyang , Podlaha Elizabeth J.
Published: February 2020

The use of hydrogen gas bubbles as a dynamic template accompanied with metal species reduction has recently been used to create porous metal thin films, where the metal deposits within spaces between bubbles. Creating porous nanowires within a nanoporous template is a greater challenge, as the gas bubbles can block the pores of the template, preventing deposition. Thus, the competition between the rate of metal deposition and hydrogen evolution reaction needs to be balanced. While this talk will focus on the electrodeposition process in creating porous metal nanowires, the selected Fe-Ni-Co material serves as a model oxygen electrocatalyst.

Conditions making it possible to potentiostatically electrodeposit porous Fe-Ni-Co nanowires using a polycarbonate (PC) nanotemplate are presented. Results show that the pH plays an important role not only in defining the rate of hydrogen evolution, but also the type of metal ion species that are reduced, leading to a change of composition. The porous structure, obtained from the solution having a pH less than 1.0, was confirmed by SEM and TEM. Such an observation is contradictory to the results from anodic alumina oxide (AAO) templates, where no nanowires or very short nanowires were found at the same conditions due to bubble coalescence. The changes in the ionic strength gradient at the electrode surface towards the bulk electrolyte, and the absorbed metal ion intermediates, are suggested to play an important role in deterring bubble coalescence making it possible to create porous nanowires.
(Invited) Electrodeposition of Au/Cu2o Core-Shell Nanowire Arrays As Photocathode Model Systems for Solar Hydrogen Production
Authors: Yang Florent , Ulrich Nils , Leber Angela , Trautmann Christina , Toimil-Molares Maria Eugenia
Published: February 2020

In the past decades, research on the synthesis and characterization of semiconductor nanowires has considerably progressed, especially for applications in the field of energy conversion, such as photoelectrochemical water splitting for hydrogen production. The dimensions, geometry, and areal density of nanowires significantly influence physical processes such as light absorption, electron-hole generation and scattering, as well as recombination of the charge carriers. Among the available fabrication methods, electrodeposition in etched ion-track membranes enables the controlled synthesis of three-dimensional assemblies of functional nanostructures with tailored composition, size and density.

We present here the fabrication and characterization of Au/Cu2O core-shell nanowire arrays consisting of a metallic core acting as nanostructured electrical contact, and a well-defined semiconductor shell responsible for light absorption and charge carrier generation and transport. The metallic Au core wires are first fabricated by electrodeposition in etched ion-track membranes. Diameter, length, and number density of the nanowires are adjusted by the membrane parameters. After dissolving the polymer membrane, the Au nanowire arrays are conformally coated by a Cu2O layer by electrodeposition. The thickness of the semiconductor layer is controlled by the deposition time. To increase their chemical stability in aqueous solutions the photoelectrodes are additionally coated with a thin TiO2 film by atomic layer deposition. The photoelectrochemical performance of these Au/Cu2O/TiO2 nanowire-based photoelectrodes will be presented, in particular, as a function of nanowire length, diameter, and areal density. The influence of the nanowire geometry and the core-shell arrangement on the generated photocurrent will be discussed in detail and compared with the photocurrents generated by planar Cu2O/TiO2 films.
Controlled Electropolymerization of Porphyrin-Based Materials
Authors: Tavakoli Elham , Kaviani Shayan , Nejati Siamak
Published: February 2020

Porphyrin-based materials have unlocalized p-electrons; additionally, they form complexes through coordinating transition metal ions and can assemble as supramolecular structures. Due to these exceptional properties, they have found widespread applications in optoelectronic devices such as solar energy harvesting systems and photonic materials[1]. Porphyrins have also been used as the building blocks of covalent organic frameworks (COFs). An example of these materials is COF 420. Conjugated Porphyrin polymer and porphyrin-based COF have shown promising performances in electrocatalysis, especially toward oxygen reduction reaction (ORR) and in fuel cells and metal-air batteries [2,3]. In this work, we investigated the parameters, influencing the electropolymerization of tetrakis(4-aminophenyl)porphyrin (TAPP) and cobalt- tetrakis(4-aminophenyl)porphyrin (Co-TAPP) in organic media. The results have shown that the morphology and crystallinity of electrodeposited film are strongly dependent on the experimental conditions such as temperature, electropolymerization rate, electrode surface, and the monomer concentration. Rational adjustment of these parameters enabled us to gain control over the growth of the crystalline domains of pTAPP and p(Co-TAPP) films. Stacking of the porphyrin frameworks via p-p interactions, we explored the possibility of bottom-up synthesis of porphyrin-COF dendrites. We observed a structure-to-function relationship between the ordering of the covalent organic polymers and their electrocatalytic activities in reducing oxygen in alkaline media.

Lian, Wenhui, et al. "Synthesis and properties of 5, 10, 15, 20-tetra [4-(3, 5-dioctoxybenzamidephenyl] porphyrin and its metal complexes." Journal of the Serbian Chemical Society3 (2012): 335-348.

Day, Nicholas U., and Carl C. Wamser. "Poly-tetrakis-5, 10, 15, 20-(4-aminophenyl) porphyrin Films as Two-Electron Oxygen Reduction Photoelectrocatalysts for the Production of H2O2." The Journal of Physical Chemistry C21 (2017): 11076-11082.

Walter, Michael G., and Carl C. Wamser. "Synthesis and characterization of electropolymerized nanostructured aminophenylporphyrin films." The Journal of Physical Chemistry C17 (2010): 7563-7574.
Electrochemical Atomic Layer Deposition: Self-Terminated Electrodeposition Reactions
Authors: Liu Yihua , Gokcen Dincer , Ahn Sang Hyun , Ritzert Nicole L. , Wang Rongyue , Gillette Eleanor , Ambrozik Stephen , Hangarter Carlos , Dimitrov Nikolay , You Hoydoo , Bertocci Ugo , Moffat Thomas P.
Published: February 2020

Recently, an inexpensive “wet form” of ALD based on self-terminated electrodeposition reactions was uncovered that enables controlled formation of ultrathin films of Pt, Ir and iron group metals and alloys thereof. Common to all these systems is the role of reaction intermediates, namely adsorbed H or OH-, in the quenching of metal deposition reactions. Further details on the mechanisms of self-terminated deposition reactions including its extension to substrates beyond Au and role in alloy co-deposition will be discussed. Likewise, the utility and relevance of the process to the synthesis of nanoparticles and thin films, and the study of bimetallic electrocatalysts will be detailed.
Stability Investigations of [Emim]AlCl4 Ionic Liquid
Authors: Shi Meng , Zhao Haiyan , Jiang Junhua
Published: February 2020

1-Ethyl-3-methylimidazolium tetrachloroaluminate, abbreviated as [EMIm]AlCl4, is a widely-investigated ionic-liquid electrolyte for electrochemical processes and energy storage applications due to its wide electrochemical window, low melting point, low vapor pressure, and high conductivity. Thermal and chemical stability of [EMIm]AlCl4 at room temperature and moderately elevated temperatures is an important factor of affecting its promising applications. The focus of this work is to systematically study the stability of [EMIm]AlCl4 at elevated temperatures.

Electrochemical studies of [EMIm]AlCl4 were first performed by measuring its open circuit potentials and cyclic voltammograms at varying temperatures and holding time. The voltammograms shown in Figure 1(a) exhibit that [EMIm]AlCl4 has a wide electrochemical window ranging from -1.6 to 1.2 V vs an Al reference electrode. The anodic and cathodic currents outside the window may correspond to the surface oxidation of the working electrode and decomposition of impurities present in the electrolyte. After the [EMIm]AlCl4 electrolyte was heated at 110 oC for 48 hours, a white suspension layer was observed at the top layer of the electrolyte, which is attributed to the formation of alumina oxides. Considerable changes of the voltammograms for the heated [EMIm]AlCl4 were shown in Figure 1(b), characteristic of the appearance of anodic and cathodic peaks in the electrochemical window and significantly increased currents. These voltammetric characters indicate the formation of electrochemical active species in the electrolyte through the decomposition of [EMIm]AlCl4.

In this presentation, we will introduce our electrochemical and analytical results regarding thermal and electrochemical stability of the [EMIm]AlCl4 electrolyte, and discuss the origins of chemical changes occurring during the thermal degradation of [EMIm]AlCl4.

Figure 1
Electrodeposition of Aluminium–Nickel Films in 1-Butyl-1-Methylpyrrolidinium-Bis(trifluoromethylsulfonyl) Amide
Authors: Ispas Adriana , Schlag Leslie , Eggert Lara , Böttcher René , Bund Andreas , Jacobs Heiko O.
Published: February 2020

The aluminum-nickel system is well characterized as multilayer thin films, as well as in mechanical alloying. Normally, one obtains the multilayers by chemical vapor or physical vapor deposition. Mechanical alloying is based on ball milling of the individual metal powders, for different time and in different molar ratios. An equimolar mixture of Ni and Al powder yields a material, which can be ignited via a self-sustaining exothermic reaction, similar to self-propagating high temperature synthesis reactions. Al-Ni powders obtained by ball milling are therefore classified as high energy powders.

An elegant and easy route to obtain Al-Ni multilayers or composites is electrodeposition. The standard electrode potential of Al(III)/Al(0) lies around -1.68 V vs. SHE (standard hydrogen electrode), while that of Ni(II)/Ni(0) is only of -0.26 V vs. SHE. Therefore, any attempt to obtain multilayers by electrodeposition is challenging, and would involve complexing chemistry. On the other hand, one can relatively easy co-deposit Al and Ni in ionic liquids, ILs, e.g., Al films with dispersed Ni particles, or Ni films with dispersed Al particles.

In this study, Al and Ni particles were prepared from the gas phase directly in ILs. The experiments were performed in 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)amide under bubbling with nitrogen gas and inside a glove box (moisture and oxygen contents below 0.5 ppm).

The co-deposition experiments were performed by cyclic voltammetry and potentiostatic depositions, in a temperature range from room temperature to 120°C. The morphology and composition of the layers were analyzed by SEM/EDX and optical microscopy and will be further discussed in this contribution.
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.
(Battery Division Technology Award) Materials and Interface Design of Lithium Metal Anodes
Authors: Cui Yi
Published: February 2020

Lithium metal anode is critical for new generation of high energy batteries. We identified that the two root causes of Li metal problems are high chemical reactivity and infinite relative volume change during Li metal plating and stripping. Nanoscale materials design represents a new powerful paradigm shift and offers new solutions to address these challenges. Here I will present our understanding and progress on: 1) Nanoscale design of host and interface for Li metal anodes; examples of host materials include graphene oxides, hollow carbon spheres, metal fluoride and oxide. We also developed robust interfacial layer materials and synthesis process for BN, Li3N and LiF. 2) Demonstration of cryogenic electron microscopy applied to battery materials research, leading atomic scale resolution of Li metal dendrite and solid electrolyte interphase. We also established the correlation of the SEI structure with battery performance.
(Invited) From Liquified Gas Electrolytes to Solid State Electrolytes - Fast Ion Conduction at Extreme Temperatures
Authors: Meng Ying Shirley
Published: February 2020

The search for solid electrolytes enabling safer, more energy dense all-solid-state-batteries has led to the revival of sulfide glass-ceramics. As such, LiPxSy have been highly touted for their high ionic conductivity. Aliovalent doping has been explored extensively to improve further the ionic conductivity, and more importantly the interphase stability between the electrolyte and electrode. In this talk, I will discuss a few (new) important design principles for superionic conductors in all solid-state batteries, in pursuit of practically viable all-solid-state batteries. On the other hand, the quest for novel electrolytes has led us to explore unexpected candidates for fast ion transport. We explored the use of liquefied gas electrolyte systems exclusively composed of solvents that are gaseous at room temperature and atmospheric pressure in rechargeable energy storage systems. We will discuss the latest discovery on using difluoromethane and fluoromethane in rechargeable lithium metal batteries with good cyclability of a high voltage lithium transition oxide cathode operated at as low as –80°C, with excellent capacity retention.
(Keynote) A Solid State Electrochemist’s View on the Requirements for Solid State Electrolytes and Electrodes for All-Solid-State Battery Applications
Authors: Weppner Werner J.F.
Published: February 2020

The advantages of solid electrolytes for new generations of high performance batteries are generally recognized. But these materials alone have no practical importance. Only suitable combinations of materials with well selected kinetic and thermodynamic properties are relevant and quite different features of solid state compared to liquid phase electrochemistry have to be taken into account. These requirements and an insight into the fundamental processes of cell operation will be discussed in terms of the various electrical and thermodynamic potentials. Electrons are often neglected, but play a most important role in the performance for both solid electrolytes and electrodes. Further, solid state electrochemical techniques will be discussed for enhancing and optimizing the search for suitable materials combinations for practical applications.
Fundamental Studies of Ion Conducting Glasses: The Combined Use of NMR and Impedance Spectroscopies to Create Models of the Conduction Energy Landscapes in Solid Electrolytes
Authors: Martin Steve W , Kmiec Steven , Shastri Ananda , Watson Deborah
Published: February 2020

We have developed, over years of study, new ways to combine NMR with Impedance Spectroscopy measurements of fast ion conducting glasses to examine the details of the ion conduction energy landscape that ions experience in conduction process. The NMR measurements of spin-lattice relaxation rates probe all ions whether they reside in energy wells so deep as to render them essentially immobile or in energy wells so shallow that their occupation time comparable to the diffusive time between adjacent sites. Impedance spectroscopy measurements, on the other hand, measure only those mobile ions that create a measurable current on the time scale of the measurement, typically seconds to microseconds. We have exploited these different measurements of the different sets of populations of the mobile ions to extract accurate predictions of the mobile ion potential energy landscapes in glass. We have found that a Gaussian distribution about a mean activation energy can provide an accurate description of the energy landscape for all of the mobile (and immobile) ions. In this talk, we will summarize more recent measurements we have made on both Li and Na ion conducting glasses and show how our methods can be used to develop predictions of glass compositions that will optimize the ion conductivity in glass.
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
Pulse Electroplating of Zinc/Nickel Alloy from a Deep Eutectic Solvent (DES)
Authors: Ryder Karl Scott , Lei Chunhong
Published: February 2020

Electrodeposition of metal coatings such as nickel, zinc, tin, chromium and cadmium for the purposes of corrosion protection has been a core interest of the electrochemical community for more than one hundred years. Cadmium has been a favourite for military and aerospace applications because of the combination of good corrosion protection and lubricity. However, cadmium salts are very toxic and hazardous and so the use of cadmium coatings is now proscribed in all but the most demanding of applications. Alternatives to cadmium coatings have included aluminium and more recently zinc nickel alloys. The latter is more accessible via aqueous methods but requires rigorous control and monitoring of bath conditions in order to maintain the composition and quality of the coating.

An alternative to aqueous electrolytes is a derivative of ionic liquids that feature eutectic mixtures of quaternary ammonium salt and hydrogen bond donor. These have become known as deep eutectic solvents (DSE). Here we have used a DES to produce coherent and adherent coatings of zinc nickel alloy in an electrochemical study and in pre-commercialisation scale-up trials.

In a digital controlled pulse-plating method, alternative forward (deposition) and reverse (stripping) currents, are applied to adjust the deposit composition and morphology, as has been demonstrated in film plating from aqueous electrolytes. This report focuses on pulse-plating γ-Zn11Ni2 alloy from a eutectic mixture of choline chloride (ChCl) and ethylene glycol (EG), also known by the commercial name of Ethaline. The effect of pulse shape and frequency on deposit morphology and crystal structure were analysed and compared with coatings derived from constant current (DC) plating methods, through Hull cell tests, XRD, and SEM/EDX measurement. The deposit composition is shown here to be dependent on the average current density, the surface morphology is not sensitive to the pulse frequency, while dendritic growth is shown to be suppressed by pulsed current. We show that the crystal grain size can be controlled according to the pulse shape and frequency. By choosing a certain shape and frequency, the pulse-plating in the DES can provide improved coating qualities and improved process control. Additionally, we have extended the laboratory investigation to pre-commercial scale-up trials with a commercial electroplating company (EC Williams, UK). This project is funded by an Innovate UK action and is entitled Cadmium Replacement Using Pulse-Plating and Ionic Liquids (CRUPPAIL). Barrel-plating trials using pulse and reveres pulse methods on small components such as screws have given even adherent coatings, Figure. The combination of pulse methods and DES electrolyte give a levelling effect, Figure (a), and good throwing power in confined geometries, Figure (b).

Figure: Scanning electron micrographs of Zinc Nickel alloy (85:15%) deposited using DES and pulse-plating on mild steel substrates, (a) sheet, (b) screws.

Figure 1