bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vanadium Electrorefining in NaCl–KCl–VCl2 Melts
Authors: Polovov Ilya B. , Chernyshov Mikhail V. , Volkovich Vladimir A. , Rebrin Oleg I. , Rylov Alexander N. 
Published: February 2020

Molten salt mixtures can be effectively employed for electrowining and electrorefining of relatively chemically active rare refractory metals having negative reduction potential. One of such metals is vanadium. However quality of the metal produced (impurities content and size of crystals in the deposit) and current efficiency in a standard vanadium electrorefining process does not fully correspond to the requirements. The current work was carried out aiming to determine the optimal conditions of operating industrial vanadium electrolysis baths.
The experiments on vanadium electrorefining were carried out in a semi-industrial electrolyser made of stainless steel. Crude vanadium metal was loaded in an anodic basket made of molybdenum. The experiments were performed in dry purified argon atmosphere, and glassy-carbon or nickel crucibles were used to contain the melt.
Vanadium-containing melts were prepared by dry chlorination of vanadium metal with subsequent absorption of chlorination products by fused salt mixtures. To stabilize vanadium(II) ions, the molten electrolyte was kept in contact with vanadium for 12–18 hours. Mean oxidation state of vanadium in the melt determined oxidimetrically was always close to two and didn’t depend on vanadium concentration.
The method of mathematical planning of experiments was used to determine optimal conditions of electrolysis. Current efficiently was chosen as a response factor. Variable parameters and their intervals were chosen on the basis of the preliminary experiments and the results of kinetic studies. Current density, vanadium concentration and specific quantity of electricity were selected as variables. Temperature had no effect on the current efficiency and increasing temperature only resulted in rising vapor pressure of the melt. Therefore, temperature was not included into variable parameters. Anodic current density was kept essentially constant between 0.1 and 0.15 A/cm2. Such anodic current density allowed maintaining average oxidation state of vanadium ions close to two in the course of the experiments.
The 23 full factor experiment was performed and the regression equation was obtained using the experimental results. All variable parameters were significant and the equation obtained was adequate. The influence of the quadratic term was insignificant. The response function was then obtained in the form of a dependence of the cathodic current efficiency on current density, vanadium concentration and specific quantity of electricity passed.
The most suitable parameters of vanadium electrorefining were determined using this equation and the experiment under the optimal conditions was carried out, Figure. The total amount of impurities in the refined product was below 0.09 wt. % and the current efficiency equaled to 0.96 g/A∙h.
Figure. High-purity electrolytic vanadium

Figure 1
Metal Oxides Solubility in Molten Salt Systems
Authors: Skryptun Igor N 
Published: February 2020

The solubility of metal oxides in alkali hydroxide melts and their mixtures with salts has been studied using the method of isothermal saturation at temperate range 673 – 873 K. The effect of temperature on the oxides solubility in melts are satisfactorily described by the linear Schroder – Le Chatellier equation ln C = A + B/T, where A and B are constants, C is concentration of oxide in melt (mole. fract.) and T is temperature (K).
Effective practical used of molten system alkali hydroxide – metal oxide depends on the knowledge of the thermodynamic properties of the system as whole as well as the partial thermodynamic properties of individual components of the system.
Thermodynamic calculations for molten binary and multicomponent systems based on that for saturated solutions meet the following equation: µ
sd = µ
sol. Since the µ
sol = µ
0
a=1(
T, p) + RTln a, where is a chemical potential of supercooled molten oxide and a is the activity of oxide in the melt relative to the supercooled molten oxide as a standard state, that lna = (µ
sd = µ
0)/RT.
Thus the temperature dependence of the activity molten oxide will be described the equation below.
On the other side ln a = ln x + ln λ and Gi
ex = RT In λ , therefore using the experimental data on the solubility of the oxides and solving the above equation we have calculated the excess relative partial molar thermodynamic quantities, which are also listed below.
The results of calculations was showed that the systems molten alkali – oxide are characterized by the deviation from the state of ideal solutions that indicate of interaction between components of the solution.

Figure 1
Importance of Proton Concentration on the Product Selectivity of the CO2 Reduction Reaction
Authors: Varela Ana Sofia , Kroschel Matthias , Ju Wen , Leonard Nathaniel , Arellano Anai , Gozález Eduardo , Bagger Alexander , Rossmeisl Jan , Strasser Peter 
Published: February 2020

The electrochemical CO2 reduction reaction (CO2RR) is seen as promising route for converting waste CO2 and excess renewable energy into valuable chemicals and synthetic fuels. During this process a variety of carbon-based products such as CO, HCOOH and hydrocarbons can be formed. The cathode material plays a crucial role on determining the product distribution during the CO2RR. For example, Cu has been found to be an interesting material on which CO2 is directly reduced to alcohols and hydrocarbons. (1) While, Ag based catalyst (2) and metal nitrogen doped materials (MNCs) are considered promising catalyst for the reduction of CO2 to CO.(3)
In addition to the catalysts material, the pH and local pH are known to be key on determining the selectivity of the reaction. In the case of Cu catalysts, we have shown that the ratio between methane and ethylene prodiuction is strongly dependent on the local pH as ethylene formation is not affected by the proton concentration. As result, in conditions in which a high local pH is favored ethylene is the predominant product, while at low pH values CH4 is favored. (4) In the case of carbon base materials, however, the influence of the reaction conditions on the catalytic performance has not been addressed.
Herein we looked into the role of the electrolyte on the selectivity of FeNC materials on CO2RR selectivity. (5) Unlike hydrogen or methane generation, CO production is independent on proton concentration on the NHE scale, suggesting a decoupled proton-electron transfer mechanism for CO formation. The similarity of the reaction mechanism with that of Metal-N macrocyclic complexes is an indication that the Fe centers incorporated to our carbon material indeed behave as the active centers of complex based catalysts.
Furthermore, our results show that on doped carbon catalysts, such as FeNC, the selectivity towards the CO2RR can be conveniently tuned by the proton availability in both aqueous and non-aqueous electrolytes.

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Figure 1
(Invited) Gas-Diffusion Electrodes for CO2 Reduction
Authors: Weng Lien-Chun , Bell Alexis T. , Larson David M , Romiluyi Oyinkansola , Weber Adam Z. 
Published: February 2020

One of the main challenges towards achieving high-efficiency solar-fuel generators performing CO2 reduction are the mass-transport limitations in traditional aqueous systems due to CO2 interactions/solubility and boundary-layer thickness. To circumvent these issues, gas-diffusion electrodes (GDEs) are considered wherein the CO2 is fed in a vapor form into a porous electrode. In this talk, we will explore the various tradeoffs endemic in GDE architectures. This is accomplished through multiphysics modeling of the cells including breakdowns of the various limiting phenomena. In addition, experimental data on the GDEs for CO2 reduction will be presented using both Ag and Cu-based catalysts. Key is understanding the potential distributions with the GDE and how this along with the observed higher current densities impact product selectivity with Cu-based catalysts. Finally, comments will be made concerning the possibilities of light inclusion in GDEs to enable solar CO2 reduction as well as the benefits of GDEs that extend beyond higher current-density operation including unprecedented control of the local environment compared to traditional, aqueous planar designs.
Acknowledgements
The material is based on work performed at the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, through the Office of Science of the U.S. Department of Energy under award no. DE-SC0004993
In-Situ Measurement of Exhaled Formaldehyde and Acetone Kinetics As Early-Stage Non-Invasive Markers of Lung Disease Using Nanostructured Polymeric Membranes
Authors: Angelopoulos Anastasios P. 
Published: February 2020

Early stage discovery of lung cancer can significantly improve patient prognosis. Unfortunately, the impact of a well-known technique such as computed tomography screening on mortality rates is uncertain. It has been postulated that tumor growth may lead to peroxidation of cell membranes and is responsible for the observed emission of volatile organic compounds (VOC’s) such as acetone and formaldehyde. This observation has stimulated significant recent effort in the measurement of these compounds in exhaled breath. While promising approaches have been developed for analyzing average VOC concentrations in exhaled breath, an unrecognized drawback to current efforts is the presumption that gas partitioning between the blood and gas phases occurs so rapidly that the time averaged concentration of collected VOCs is representative of their saturation concentration in the lungs. In fact, when one considers the mass transport resistances encountered, VOC lung concentration is likely to be time-dependent and any sensing approach must have sufficient time resolution to capture the dynamic evolution of this concentration during a typical breath exhalation period of not more than 40 seconds in a high humidity environment.
In this presentation, we describe development of an optical exhaled gas sensing approach utilizing a nanostructured polymeric membrane that meets these requirements and demonstrates the dynamic evolution of exhaled breath biomarker concentration. We show that the activity of a solid acid catalyst toward the heterogeneous condensation reactions of immobilized resorcinol reagent with gas-phase acetone and formaldehyde can be preserved even at 100% ambient relative humidity through the incorporation of organic acids such as vanillic or tiglic. The reaction produces a colored flavan and poly-condensation products that permits highly selective and sensitive correlation to acetone and formaldehyde concentrations in exhaled breath. Such behavior relies on the complex heterophase morphology of the membrane as will be described.

Figure 1
Synthesis of CuInS2 Compound Solar Cell Nanoparticles in an Aqueous Solution By Controlling the Concentration of Metal Complexes
Authors: Satou Kouhei , Yokoyama Shun , Takahashi Hideyuki , Tohji Kazuyuki 
Published: February 2020

CuInS2(CIS) is one of the most effective photovoltaic devices for developing high stability and low cost solar cell. Bandgap of CIS is 1.5eV while ideal band gap for solar cell is 1.4eV, so CIS is suitable as solar cell materials. Moreover, unlike Cu(In,Ga)Se2(CIGS), it does not contain toxic materials, such as Se [1]. Until now, CIS solar cells have been synthesized by utilizing gas phase method. However, the gas phase evaporation process needs high energy consumption, high initial cost, and large amount loss of resources. For spreading the solar cells greatly, it is required to develop a method which can resolve the above problems, so it is necessary to synthesize CIS solar cells in liquid method.
Here, we have already developed a synthesizing method of single phase and homogeneous Copper-Indium (CI) alloy nanoparticles in an aqueous solution. In this method, the concentration ratio of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction reaction rate is also controlled. Synthesized CI nanoparticles were spin coated onto substrate and selenized, consequently it shows the photo voltaic effect. Thus, printable solar cell can be formed by using this method. However, CIS2 nanoparticles were not synthesized until now, because of ligand exchange reaction between the complexing agents and Cu and In.
Therefore, in this study, to prevent these undesirable reaction, we tried to control the condition of Cu-In-complexing reagent(s) system precisely by using the calculation. By using these calculation results, CIS2 particles were tried to synthesized in an aqueous solution
Results of calculation indicated that iminodiacetic acid (IDA) was appropriate complexing reagent. In the ternary system of Cu-In-IDA, it was calculated that the Copper comlexes and Indium complexes can be restricted to homogenized species, [(Cu2+)(IDA)] (pH3) and [(In3+)(IDA)2] (pH3) under the condition that the total molar concentration of Copper and Indium ions were 5 mM, respectively.
Based on this calculation, a solution under the above condition was prepared, and both metal complexes were tried to co-sulfurize. As a results, particles with amorphous like morphology were obtained. Therefore, in order to improve the crystallinity, the particles were heated for 30 min at 500 °C under N2 atmosphere. XRD results of heat treated samples indicated that several peaks with a dominant CIS2 peak were observed. Thus, it can be said that CIS2 nanoparticles were successfully synthesized in an aqueous solution, without undesirable ligand exchange reaction during reaction.
These results indicated that homogenize metal complexes system of Cu-In-IDA are essential for the synthesis of CIS2 particles.
In our presentation, detailed and another results will be introduced.
[1]Recent Development of Thin Film Compound Semiconductor Photovoltaic Cells, Wada, Publication of CMC, 2007
Electrochemical Tuning of Ordered Mesoporous Oxides with Spinel and Perovskite Structures for Reversible Control of Magnetization
Authors: Brezesinski Torsten 
Published: February 2020

Nanoporous oxides in thin film format have been receiving much attention in recent years, especially because of their potential for next generation device applications. However, the preparation of non-siliceous (mixed-metal) oxides that are structurally and compositionally well-defined is challenging. The primary reason is that both the nucleation and growth of the crystalline phase are usually difficult to control.
Here we describe the block-copolymer-templating synthesis (using an evaporation-induced self-assembly process) of a series of high quality large-pore mesoporous oxides with spinel and perovskite structures, including metal ferrites and mixed-valence manganese oxides, and their characterization by various imaging, diffraction, and spectroscopic methods. Besides, we demonstrate that the general idea of combining nanomagnetism and electrochemical energy storage concepts can be applied to block-copolymer-templated mixed-metal oxide thin films. Using such high-surface-area materials as the working electrode in lithium-ion battery cells or supercapacitors and carefully controlling the charge/discharge potential allows tuning (virtually fully reversible) the magnetism at room temperature without compromising the lattice and/or pore structure.[1-4] The results are exciting and clearly show that both techniques hold potential for application in the fields of micromagnetic actuation and spintronics to name a few.
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Super Slippery Surface for Small Volume of Liquid on Superhydrophilic Nanoscale Texture
Authors: Fujikane Masaki 
Published: February 2020

In order to realize the excellent functional antifouling coating, the anti-adhesive property is requiring for the material surface. The photocatalyst material such as TiO2 are conventionally used for degrading pollution [1,2]. The superhydrophobic bumps such as lotus leaf structure [3,4], or super slippery surface such as Nepenthes pitcher plant are also conventionally used for self-cleaning function [5,6]. These functional surfaces, however, have been applied in limited practical use due to their difficulties in processability, wearability, permeability and resupplying the lubricant.
This paper reports the first example of super slippery surface using superhydrophilic material, which is opposite approach to generally using superhydrophobic material as mentioned above. The newly discovered superhydrophilic slippery surface has been realized by nanotextured photocatalyst with surface reforming process. Without hydrophobicity or lubricant, it has been succeeded in sliding waterdrops smaller than 5 μL with sliding angle lower than 5° (Fig. 1).
The GaN substrate has been selected as photocatalyst in this study, and 100 nm in diameter SiO2 nanoballs have been dip coated on the substrate in the shape of single layered colloidal crystal following surface modification of the substrate. The nanotexture has been formed by dry etching process with hexagonal closed packed structure SiO2 nanoball etching mask [7–9]. Finally, the nanotextured GaN surface has been modified again to superhydrophilic then the super slippery surface has been finished up [10]. The obtained new phenomenon, i.e. super slips on superhydrophilic surface, is supposed to be affected by the fractal curve at the 3-phase (water, GaN and air) contact line, and by the super low friction coefficient between waterdrop and nanotexture that likes commonly used Cassie-Baxter model.
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[10] M. Fujikane, EU patent 17167854.3 (2017).

Figure 1 | Relation between the water volume and the sliding angle for different types of surfaces. The values in parentheses at the end of graph legends indicate static contact angle with 2 μL water probe.

Figure 1
Synthesis and Caracterization of ZrO2/PANI Composite As Electrocaltalyst Support for Direct Alcohol Fuel Cells
Authors: Rivas S. , Calleja Gerardo , Guerra-Balcázar Minerva , Ledesma-García Janet 
Published: February 2020

Carbon Vulcan has been widely used as electrocatalyst support despite its susceptibility to electrochemical corrosion. Zirconium oxides are a promising alternative due to its corrosion resistance in acid and alkaline media, the main drawback of these materials are their low conductivity and surface area. Therefore, an alternative to overcome this is, to develop a composite with conducting polymers (CPs) like polyaniline. conducting polymers fulfill the main requirements for fuel cell application: high surface area, to obtain high metal dispersion, suitable porosity, high electrical conductivity, and high stability under fuel cell operational conditions.
In this work Pt as electrocatalyst was supported by chemical reduction onto nanostructured ZrO2 followed by chemical deposition of PAni. Every element of the composite was characterized individually. Zirconium oxide was synthesized by sol-gel technique, using different calcination temperatures (300 and 350 °C), TEM analysis shows that zirconia has a particle size between 100 and 1000nm in a disperse pattern with some agglomerates, the X ray diffraction pattern correspond to an amorphous structure. The surface area was determined by nitrogen adsorption and goes from 60 and 160m2/g depending on calcination temperatures.
PAni was synthetized by chemical method and showed different morphology depending on incubation temperature and with different corresponding conductivity capacities. When the bath temperature was at -16°C a notorious microfibrillar pattern could be seen by SEM analysis, but the sample color was not characteristic of emeraldine (conductor PAni salt). However, when bath temperature was 2 and 20°C, the color allowed to confirm that emeraldine was the PAni phase presented but with porous nanoparticular morphology.
From previous experimental work it is clear that Pt/ZrO2 has a superior performance towards methanol oxidation reaction than Pt/C (20%), especially on alkaline conditions. In this work, the synthesis of PAni over Pt/ZrO2 does not affect the electrocatalytic activity neither in acid or alkaline conditions. Therefore, the low surface area of zirconium could be properly compensated with this conductive polymer. However, stability tests are necessary to consider this composite as adequate substitute for carbon based electrocatalysts supports in direct alcohol fuel cells.