bluuebunny/crossref_metadata_2025 huggingface dataset:
Facile Synthesis of Anhydrous Metal Fluoride Nanocomposites Using Ammonium Fluoride and Their Application to High Performance Lithium-Ion Battery Cathodes
Authors: Chun Jinyoung , Kim Youngsik , Lee Jinwoo
Published: February 2020

Among various metal compounds, metal fluorides (MFx) are one of the promising cathode materials for Li-ion batteries (LIBs) as they exhibit high theoretical conversion potentials as well as large specific capacities. However, only a limited number of synthetic method, generally involving highly toxic or inaccessible reagents, currently exist, which has made it difficult to produce well-designed nanostructures suitable for use as cathodes; consequently, harnessing their potential cathodic properties has proven challenging over the past several decades.

  In this study, in order to address these critical issues and realize potential cathodic performance of MFx in LIBs, we have developed a new and facile bottom-up approach using ammonium fluoride (NH4F) to synthesize anhydrous MFx(CuF2, FeF3, and CoF2)/mesoporous carbon(MSU-F-C) nanocomposites. We discovered that various metal precursor nanoparticles pre-confined in mesoporous carbon can be directly converted to anhydrous MFx by simple heat treatment with NH4F under solventless conditions. Furthermore, we also demonstrate the versatility, mild toxicity, and efficiency of this synthetic method, and, using XRD analysis, propose a mechanism for the reaction. As the cathodes of LIBs, all MFx/MSU-F-C prepared in this study exhibited superior electrochemical performances, through conversion reactions. In the case of FeF3/MSU-F-C, it maintained a capacity of 650 mAh g−1
,FeF3 across 50 cycles, which is ~90% of its initial capacity; to the best of our knowledge, no such an excellent cycle performance of FeF3 with a high capacity through conversion reactions has previously been reported. CuF2/MSU-F-C and CoF2/MSU-F-C cells also retained 209 mAh g−1
,CuF2 (at the 20th cycle) and 400 mAh g−1
,CoF2 (at the 30th cycle) of discharge capacities, respectively. These results show excellent performance in comparison to previous studies; in particular, this is the first result which shows promising cycle properties of CuF2. We expect that this new synthetic method would open an avenue to application of metal fluorides to cathodes in LIBs and will be adopted by many scientists & engineers for their future research.
(Invited) Electrospun Electrolytes and Electrodes for Li-Ion Batteries
Authors: Croce Fausto
Published: February 2020

The quest for more efficient and low environmentally impacting energy conversion and storage technologies has become a priority for modern society. In particular, rechargeable, high capacity and high power electric energy storage systems, if developed, would play a central role in accelerating the transition toward an electric transportation economy, which, in turn, would dramatically reduce the risks associated with the burning of fossil fuels. To this purpose, ‘ad hoc’ engineered functional materials that join improved electrochemical properties with scalable preparation process for electrodes and electrolytes are needed. The most promising of such materials are those with nanometric-scale dimensions, including nanoparticles and nanofibers. These materials, having very high surface to volume ratio, show enhanced bulk charge transport and faster electrodic reaction rates. Nowadays, new methods have emerged for manipulation, assembly and characterization of nanostructured materials, particularly regarding functional electrodes and electrolytes based on nanofibers. Among the methods for generating nanofibrous structures, electrospinning is a top-down approach proved to be simple, cost effective and versatile, which allows the fabrication of polymeric and inorganic nanofibers in a scalable process. Electrospinning is based on the application of an electric field to a drop of a viscous solution on the tip of a spinneret. The electric field elongates the drop to form a conical shape known as the Taylor cone. For an electric field critical value, the repulsive electrical forces between the charges in the fluid overcome the surface tension of the drop and a charged jet of the solution is ejected from the tip of the Taylor cone. The jet becomes unstable and rapidly whipping leading to the evaporation of the solvent and the formation of dry, continuous, ultra-thin fibers on the collector [Fig. 1]. The collected electrospun mats present peculiar properties, such as very high surface to volume ratio, low density, high pore volume and remarkable mechanical strength.

            In this presentation, the electrospinning technique will be illustrated particularly regarding the optimization of the system and process parameters, which mostly influence the electrospun nanofibers. The characteristics of some gel electrolytes formed by electrospun polymeric separators based on PVdF and PEO will be discussed. Finally, the preparation by co-electrospinning followed by air stabilization and carbonization of nanosized, active, electrodic particles embedded in electrically conducting Porous Multichannel Carbon MicroTubes (PMCMT) will be described [Fig. 1] and the performances of composite electrodes prepared using Sn- PMCMT, Si-PMCMT and Li2S-PMCMT powders illustrated.

Fig.1

Figure 1
On Printable in Situ Electrolyte Filled Battery Separators
Authors: Paschinger Werner , Bismarck Alexander
Published: February 2020

Modern Li-Ion batteries are multicomponent systems involving advanced materials and technologies. One part highly influencing performance and safety of the arrangement is the separator. Separators can be divided into three groups: (i) macroporous polymers, (ii) non-woven fabric mats and (iii) inorganic composite membranes. In any case the manufacturing of these separators has to be done in a multistep process, often involving the use of compounds harmful or toxic to the environment and being energy intensive overall. Polymerized high internal phase emulsions (polyHIPEs) are porous emulsion-templated polymers synthesized within high internal phase emulsions (HIPEs). HIPEs are highly viscous, paste-like emulsions in which the major, “internal” phase, usually defined as constituting more than 74% of the volume, is dispersed as discrete droplets within the continuous, minor, “external” phase. Recently they have attracted attention due to their possible application as in situ electrolyte filled separators for Lithium ion batteries. Using RT-IL based electrolytes, stable HIPEs have been synthesized and successfully casted as thin films with thicknesses lower 100μm. UV polymerized material shows an open porous structure and thermal stabilities up to at least 200°C. Conductivity measurements resulted in McMullin numbers below a value of 2 that increases with increasing temperature, suggesting some possible thermal shutdown mechanism. Based on these results, the most promising formulations were chosen and directly casted and polymerized onto commercial Li-electrodes followed by long term stability tests. As energy storage nowadays becomes more and more important in situ electrolyte filled polyHIPEs are of interest as they could provide a possible way in preparing highly advanced materials for economic manufacturing of Lithium ion batteries.
Separation of Reaction and Storage in Li-Air Battery
Authors: Takechi Kensuke , Mizuno Fuminori
Published: February 2020

Non-aqueous Li-air battery has intensively been investigated due to its ultla-high energy density, however, its serious concerns have not been completely solved yet, such as severe cycle fading and low current density. The major cause of the issues can be attributed to a deposition of discharge product on the cathode surface because the deposition results in a clogging of the pore in the cathode preventing continuous steady discharge and in its chemical and/or physical electronic isolation from cathode even after charge.1 In other words, a fundamental difficulty which resides in Li-air architecture can be described as; ‘electrochemical reaction and discharge product storage take place at the same location, on the cathode’.

Based on the discussion, we simply came to the conclusion that we needed to separate ‘electrochemical reaction and discharge product storage’ to solve above-mentioned fundamental issues. In this presentation, we propose a new concept Li-air battery which discharge product (Li2O2) can be stored in its electrolyte instead of on the cathode (fig. 1). The new battery architecture can be realized by simply replacing its original electrolyte to a new composite one. The cathode is able to maintain itself in a steady state during discharge because the discharge product is not deposited on it, and the new Li-air has performed much higher current density and capacity than the regular (old) architecture Li-air (fig. 2). We also demonstrate performances of the new Li-air even in the ambient air operation.

Y. Hase, E. Ito, T. Shiga, F. Mizuno, H. Nishikoori, H. Iba, K. Takechi, Chem. Commun., 49, 8389 (2013).

Figure 1
Novel Ether- or Sulfur-Functionalized Ionic Liquids As Electrolyte Components in Advanced Lithium Batteries
Authors: Navarra Maria Assunta , Lombardo Lucia , D'Annibale Andrea , Appetecchi Giovanni Battista , Panero Stefania
Published: February 2020

Although lithium batteries have tremendous potential, the flammability of the organic electrolyte commonly used hinders their consideration for large-scale applications, where the battery is expected to operate over a wide temperature range without compromising safety. To combat flammability, highly stable ionic liquids (ILs), entirely composed of ions and having negligible vapour pressure, have been widely investigated as electrolytes [1].

Tailored, in-house synthesized new ILs, based on cyclic quaternary ammonium cations, having no double bonds or acidic protons reacting with lithium, and bis(trifluoromethanesulfonyl)imide (TFSI) anion, will be here presented. A comparison between two families of ionic liquids, with ether- or sulfur-functionalized aliphatic side chains in the cation moiety, will be described. Their thermal and electrochemical properties, including the definition of the stability window, interface characteristics towards carbon-based and lithium electrodes, will be discussed. Electrochemical performances in advanced lithium cell configurations, adopting electrolytes based on the proposed ILs, will be finally presented. Tests in Li/S cells have revealed good reversibility of the polysulfides redox process and appreciable capacity, combined with good retention and coulombic efficiency leveling 99 %.

[1] M. A. Navarra, MRS Bulletin, volume 38, year 2013, pages 548 - 553: “Ionic liquids as safe electrolyte components for Li-metal and Li-ion batteries”.
(Invited) The Solid-State Lithium Secondary Batteries: Its Possibility Beside the Sulfide Electrolytes
Authors: Aihara Yuichi
Published: February 2020

Lithium-ion battery was commercialized in 1991, and its market has grown tremendously for IT mobiles. Today, the demand for high energy density is rapidly increasing for automotive and stationary energy storage. In the history, lithium metal secondary battery has attracted great attention for digital media applications about thirty years ago. However, due to significant technical challenges such as dendrite formation during charge-discharge cycles, its development had faded and the interests shifted to lithium-ion batteries. From the view point of energy density, the interest is coming back and effort for the lithium metal and related alloys is intensifying.

              In this presentation, our recent work on the fabrication of all-solid-state batteries and sulfide solid electrolyte development will be reported. The sulfide solid-state batteries have the advantages of (1) small grain boundary resistance, (2) fast kinetics at Li/solid electrolyte interface, (3) stable cycle with a lithium metal anode, (4), lack of convection of the electrolyte material, and (5) non-volatile and incombustible electrolyte. [1-3] We have demonstrated charge-discharge operation of solid state Li-S batteries, and verified its low activation energy of the charge transfer process at the anode. Further improvements are still needed in the loading-level of active materials and cell performance.

              Besides the fabrication of the solid-state cells, our efforts on the materials development will be presented. In particular, some results on LiI substituted Li3PS4 solid electrolyte will be shown. This material is amorphous and exhibits >1mScm-1at 25℃.[4] Finally, challenges and outlook of our research and development will be discussed.

S. Ito, et al., J. Power Sources 248 (2014) 943.

M. Agostini, et al., Solid State Ionics 244 (2013) 48.

T. Yamada, et al., J. Electrochem. Soc.(2015) A646.

Y. Aihara, et al., elsewhere
(Invited) Electrochemical Synthesis of High Strength Regular Metal Foams and 3D Micro-Lattices
Authors: Mieszala Maxime , Hasegawa Madoka , Mischler Stefano , Michler Johann , Philippe Laetitia
Published: February 2020

Three-dimensional metal micro- and nanostructures offer opportunities to develop multifunctional materials with unique combinations of material properties. Traditional strategies to improve the mechanical properties of materials consist of altering either the microstructure or the composition. Both strategies, albeit successful, tend to be rather incremental. The third approach is that of controlling not only the microstructure but also the architecture1. By combining the effect of the architecture with the effect of the microstructure, architectured cellular materials with enhanced mechanical properties are achieved.

Modern templating techniques, including colloidal crystal lithography2 and 3D laser lithography3, enable the creation of structures with well-defined sub-micron features. Used in combination with electrochemical routes, the deposition of nickel or copper micro-architectures is achieved with fine control of the microstructure and dimensions. Although electrodeposition is a well-established technique, metal electroforming of cellular micro-materials is demanding. Specific challenges include the electrodeposition onto non-conductive surfaces, adequate surface preparation, appropriate throwing power for electrolyte infiltration into submicron features or proper process optimization.

The present talk will cover our recent research activities on the fabrication of nickel and copper regular foams and micro-lattices synthesized by electrochemical processes aiming at achieving high strength and low density materials. Regular porous metal structures are produced by colloidal crystal templating of polystyrene (PS) microspheres. The PS templates are formed by sedimentation of PS microspheres. Under gravity and drying, the PS microspheres form a self-assembled multilayer with a face-centered cubic structure. The templating step is followed by either metal electrodeposition to obtain a metal inverse opal (Figure 1.a) or by electroless deposition of NiB to form a hollow-shell opal (Figure 1.b). The metallic micro-lattices (Figure 1.c) were fabricated by electroless deposition of NiB onto a surface-modified polymer template produced by 3D laser lithography. In situ micromechanical testing of these micro-architectures showed enhanced mechanical properties despite being low density. Increasing the metal coating in micro-lattices from 10 nm to 100 nm improve the mechanical performances by a factor of 3.5 while the density is only multiplied by 2.3.

References:

1 M.F. Ashby, Philos. Trans. A. Math. Phys. Eng. Sci. 364, 15 (2006).

2 A. Stein and R.C. Schroden, Solid State Mater. Sci. 5, 553 (2002).

3 J. Bauer, S. Hengsbach, I. Tesari, R. Schwaiger, and O. Kraft, Proc. Natl. Acad. Sci. U. S. A. 111, 1 (2014).

Figure 1
Deposition of Pt Nanoparticles on Ni Foam Via Galvanic Displacement
Authors: Tamasauskaite-Tamasiunaite Loreta , Zabielaite Ausrine , Balciunaite Aldona , Sebeka Benjaminas , Stalnioniene Irena , Buzas Vytenis , Maciulis Laurynas , Tumonis Liudas , Norkus Eugenijus
Published: February 2020

In the present study the Ni foam was modified with Pt nanoparticles via the galvanic displacement technique. A thin electroless Ni sublayer was deposited on the Ni foam substrate. Then, Pt nanoparticles were deposited on Ni/Nifoam by its immersion into a platinum(IV)-containing solution for various time periods. The morphology, structure and composition of the prepared catalysts were examined by means of Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, X-ray Diffraction and Inductively Coupled Plasma Optical Emission Spectroscopy. The catalytic activity of Pt(Ni)/Nifoam with different Pt loadings was determined by measuring the amount of hydrogen generated directly from aqueous alkaline solutions of sodium borohydride and compared with that of Pt. The data on hydrogen generation volume with respect to time at different concentrations of sodium borohydride and different temperatures have been presented. 

It was found that the Pt(Ni)/Nifoam catalysts show enhanced catalytic activity towards hydrogen generation as compared to that of Ni/Nifoam.

 Acknowledgment

This research was funded by a Grant (No. TEC-06/2015) from the Research Council of Lithuania.
Electroless Metallization of Stereolithographic Photocurable Resins for 3D Printing
Authors: Bernasconi Roberto , Credi Caterina , Natale Gabriele , Tironi Marco , Levi Marinella , Magagnin Luca
Published: February 2020

In the last few years the introduction of affordable 3D printing techniques like fused deposition modeling (FDM) and stereolithography (SLA) is slowly changing the way mass production has always been intended. The possibility to obtain complex shapes in a short time directly at home, without using conventional manufacturing techniques, is a revolutionary concept that is finding a lot of different applications. However some limitations exist for 3D printing, the most important one being the manufacture of metallic objects. Metals offer many attractive properties like electrical and thermal conductivity or a good mechanical resistance, and for this reason the 3D printing of metallic objects is a strategic research field in additive manufacturing. Some techniques able to directly print using metals are available, but many limitations are present in this case. For this reason the most used method to obtain bulk metallic parts is the use of the printed polymeric version as a mold to cast the final object. In most applications however only a thin layer of metal is required and different methods can be used to coat a printed part, including PVD and all-wet metallization. The latter is in general preferred due to the low cost and the optimal coverage in the case of critical shapes of the printed part. Optimized methods are available for the metallization of FDM printed objects [1], while in the case of SLA manufactured samples only some aspects of the plating process are treated in the existing literature [2, 3].

The present work investigates an optimized method to metallize parts obtained with SLA 3D printing by mean of an all-wet process based on electroless plating. The behavior of different proprietary and custom made photocurable resins printed using a commercial laser stereolithographic printer is investigated. The coatings employed include nickel-phosphorus and copper, two metals typically deposited via electroless plating on polymers. The metallization is characterized from the fundamental point of view on planar samples, while in a second time some examples of complex shapes metallization are provided. In particular the metallization of micrometric parts is studied. Finally the possibility to deposit other layers of different metals via electrodeposition on the first coating obtained by electroless plating is analyzed.

[1] R. Bernasconi et al.; ECS Trans., 66 (19), 23 (2015)

[2] A. Macor et al.; Rev. Sci. Instrum., 83, 046103 (2012)

[3] B. Luan et al.; Appl. Surf. Sci., 156, 26 (2000)
(Invited) Progress on Electroless Atomic Layer Deposition
Authors: Stickney John Lewellen , Benson David M. , Jagannathan Kaushik
Published: February 2020

Atomic layer deposition (ALD) is a group of methods for the formation of nanofilms of materials, an atomic layer at a time using surface limited reactions.  The majority of those methods are based on use of the vacuum environment.  However there are methods such as sequential ionic layer adsorption reaction (SILAR) which uses the condensed phase, that is, aqueous solutions of precursor ions.  In addition, this group has been working on an electrochemical form of ALD for 25 years.   That work is referred to as electrochemical atomic layer deposition (E-ALD) or electrochemical atomic layer epitaxy (EC-ALE), and is based on using underpotential deposition (UPD) for surface limited reactions. The problem with using an electrochemical methodology for the formation of nanofilms is that many compatible with the conductive substrates normally used for E-ALD.  This has stimulated investigations into the growth of materials using an electroless form of ALD (EL-ALD).  The processes being explored are based on use of an adsorbed layer of a precursor, where the solution is then exchanged for a reducing agent, or vis versa.   This cycle is then repeated to desired thickness. One example is the use of an adsorbed (or absorbed) layer of hydrogen as the reducing agent (usually on Pd).  This is then used for surface limited redox replacement (SLRR) of the desired element.  Another example is the use of Sn2+ adsorption followed by Pd2+, which oxidizes the Sn2+ to Sn4+ and forms Pd on the surface. Studies are underway to build this into a cycle for EL-ALD.
Magnetic Field and Substrate Effects on the Electrodeposition of High Magnetostrictive Cofe Films
Authors: Pillars Jamin Ryan , Langlois Eric Donald , Arrington Christian L. , Monson Todd
Published: February 2020

Magnetostrictive CoFe films were investigated for use as magnetoelastic tags or sensors. The ability to electrodeposit these films enables batch fabrication processes to pattern a variety of geometries while controlling the film stoichiometry and crystallography. Previous research developed a chemistry and plating parameters to maximize magnetostriction with a stoichiometry range of Co0.7-0.75Fe0.3-0.25and 20-30nm grain size. To further optimize the magnetostriction of electrodeposited CoFe films, the effect of the substrate was examined using copper, gold, and nickel electrodeposited base layers with varying preferred orientations and grain sizes. X-ray diffraction spectroscopy and electron backscatter diffraction were used to determine the crystal structure and crystallite size. Additionally, a hard magnet setup was used to apply a magnetic field during electrodeposition of the CoFe alloy to control the alignment of the magnetic domains. Magnetic force microscopy was used to determine the magnetic structure of the films as a function of the applied field’s magnitude and direction. Magnetic field and substrate effects were then correlated to magnetostriction performance.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
Area-Selective Electroless Deposition of Gold Nanostructures with Various Morphologies on Silicon Assisted By Focused Ion Beam Irradiation
Authors: Itasaka Hiroki , Nishi Masayuki , Shimizu Masahiro , Hirao Kazuyuki
Published: February 2020

Electroless deposition of metal onto semiconductor is an efficient technique to fabricate metal nanostructures for electronic, photonic, and plasmonic applications. We previously reported a new area-selective electroless deposition of gold nanostructures on a crystalline silicon substrate. A simple tetrachloroauric(III) acid (HAuCl4) solution using water or alcohol as a solvent is dropped on a crystalline silicon substrate preprocessed with a focused ion beam (FIB) or a femtosecond laser. Gold nanostructures selectively grow on the preprocessed area on the silicon substrate[1]. Hydrofluoric acid, which is commonly used for electroless deposition of metal on semiconductor, is unnecessary in our method. Our previous work revealed that silicon dangling bonds induced by the preprocessing reduce gold ions in the solution[2]:

3Si• + Au3+ + 3ROH → 3Si-OR + Au + 3H+  (R = H or CnH2n+1)

where Si• represents the silicon atom which has a single dangling bond and three covalent bonds with other silicon atoms. This reductive reaction requires hydroxyl groups of solvent molecules and initiates the nucleation of gold. However, the overall mechanism of the gold growth in our method is still unclear.

Here we focus on the growth stage of gold after the nucleation stage. For investigation of growth mechanism of gold, we quantitatively evaluate the amount of gold grown on FIB-irradiated silicon surface with a fixed microscopic area by measuring the thickness of gold. The quantitative evaluation indicates that once the gold/silicon interface is formed through the nucleation stage, electrons in crystalline silicon surrounding the FIB-irradiated silicon reduce gold ions in the solution across the interface. Therefore the difference in the Fermi level between silicon and the solution is the driving force in the growth stage. This mechanism is supported by a new two-step growth process introduced to our method, in which the exposure of the FIB-irradiated silicon substrate to HAuCl4 solutions is separated into the first and second steps. Once the gold/silicon interface is formed in the first step, the gold growth proceeds in the second step with or without silicon dangling bonds and hydroxyl groups of solvent molecules. Furthermore, our new method enables us to fabricate gold nanostructures with various morphologies by selecting the reaction condition in the second step.

References

H. Itasaka, M. Nishi, Y. Shimotsuma, K. Miura, M. Watanabe, H. Jain, and K. Hirao, J. Ceram. Soc. Jpn.
122,543 (2014).

H. Itasaka, M. Nishi, and K. Hirao, Jpn. J. Appl. Phys.
53, 06JF06 (2014).
Enhanced Catalytic Efficiency and CO Tolerance of Novel Pt Nanostructures Prepared By Pulsed Electrodeposition for Fuel Oxidation Reaction
Authors: Chen Po Chang , Chuang Chen Kang , Yeh Tsung-Kuang
Published: February 2020

Innovative support-free platinum (Pt) nanostructures were developed in this study for enhancing the anode catalyst activities and the power density of single cell for proton exchange membrane fuel cell (PEMFC) application. The platinum nanostructures were directly grown on carbon paper by a pulsed electrodeposition technique. The morphology of Pt nanostructures were investigated by SEM, and shown as dendritic structures instead of nanoparticles. A cyclic voltammetry analysis was carried out for characterizing the behavior of methanol oxidation on specimen bearing the Pt dendritic nanostructures in mixed 1 M methanol and 0.5 M sulfuric acid solutions. With its unique morphology, the Pt dendritic nanostructures could exhibit a good carbon monoxide tolerance and high efficiency without the joined Ruthenium (Ru) catalyst, which is very different from pure Pt nanoparticles. After the electrochemistry analysis, the single cell test was performed with our homemade dendritic Pt catalyst to understand the efficiency of the cell. Then we compared it with the commercial Pt-black catalyst at the same loading of the platinum catalyst.
Electroless Deposition of Cobalt-Tungsten-Boron Films from Glycine Containing Solutions As Barrier Layer Against Cu Diffusion
Authors: Norkus Eugenijus , Sukackienė Zita , Tamasauskaite-Tamasiunaite Loreta , Naujokaitis Arnas , Jasulaitiene Vitalija
Published: February 2020

Electroless cobalt films have been demonstrated to produce high quality barrier and capping layers for Cu. The best barriers so far include, in addition to the cobalt, refractory metals ions (e.g., W, Mo, or Re), and either phosphorus or boron. Electroless cobalt and its alloys can be used in micro- and nano-technologies, e.g. for microelectro-mechanical systems (MEMS), as well as for ultra large-scale integration (ULSI) technology of integrated cicuits.

In this work we present novel deposition solutions that is used to form cobalt-tungsten-boron films used morpholine borane as reducing agents. The films of cobalt that cointain small amounts of tungsten and boron were deposited by the electroless process. The cobalt-tungsten-boron coatings were deposited on the copper surface using a solutions containing (mol l-1): CoSO4 - 0.1, NH2CH2COOH (glycine) – 0.2, C4H8ONH·BH3 (morpholine borane) – 0.2, Na2WO4 – (0-0.02), C6H8O7 (citric acid) – 0.175. The bath operated at pH 7 and 60 ºC. The thickness of the compact cobalt-tungsten-boron coatings obtained under optimal operating conditions were ca. 0.5 µm. The morphology and strukture of the cobalt alloys were characterized by means of Field Emission Scanning Electron Microscopy. The composition of the cobalt-tungsten-boron films obtained was determined by means of X-ray Photoelectron Spectroscopy using an ESCALAB MKII spektrometer. To obtain depht profiles, the sample were etched in the preparation chamber by ionized argon at a vacuum of 5·10-4 Pa.

The mikrostructure of the coatings changes with the intercorporation of tungsten into the coatings. The particles of cobalt-tungsten-boron films are larger and almost equilateral as compared with the cobalt-boron particles. XPS depth profile investigation does not show any significant diffusion of Cu atoms into cobalt after heat-treatment of the cobalt-tungsten-boron film. This fact confirms that the cobalt-tungsten-boron thin layer, deposited from glycine containing solutions, serves as a perfect diffucion barrier to prevent Cu diffusion. 

This research was funded by a Grant (No. TEC-06/2015) from the Research Council of Lithuania.
Decoration of Fiber Structure Co with Pt or Au Nanoparticles for Catalytic Ppurposes
Authors: Zabielaite Ausrine , Antanaviciute Kornelija , Balciunaite Aldona , Tamasauskaite-Tamasiunaite Loreta , Norkus Eugenijus
Published: February 2020

In the present study the activity of the Co with a fiber structure decorated by Pt or Au nanoparticles (denoted as Pt/Cofiber and Au/Cofiber) was investigated towards the electro-oxidation of hydrazine. At first, Co coating with a fiber structure and the thickness of ~3 µm was electroplated onto the Cu surface. Then, the Pt nanoparticles were deposited on the prepared Cofiber/Cu by its immersion into the 1 mM H2PtCl6 + 0.1 M HCl solution at the temperature of 25 oC for 10-60 s, respectively, whereas Au nanoparticles were deposited on Cofiber/Cu by its immersion into the 1mM HAuCl4 + 0.1 M HCl for 10-300 s. Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and Inductively Coupled Plasma Optical Emission Spectroscopy were used for determination of morphology, structure and composition of the prepared catalysts. The electrocatalytic properties of catalysts were evaluated with respect to the electro-oxidation of hydrazine in an alkaline medium by means of cyclic voltammetry and chrono-techniques.

It was found that the Pt loadings were 5, 15 and 29 µg cm–2 in the prepared Pt(Cofiber)/Cu catalysts after the immersion of Cofiber/Cu into the platinum-containing solution for 10, 30 and 60 s, respectively. The Au loadings were 20, 28 and 96 µg

cm–2 in the prepared Au(Cofiber)/Cu catalysts after the immersion of Cofiber/Cu into the gold-containing solution for 10, 60 and 300 s, respectively. The cobalt with a fiber structure decorated with the Pt or Au nanoparticles show enhanced electrocatalytic activity towards the electro-oxidation of hydrazine in an alkaline medium as compared to that of bare Co deposited on the Cu surface.

 
Acknowledgment

 This research was funded by a Grant (No. TEC-06/2015) from the Research Council of Lithuania.
Electrochemical Properties of Ni-TiO2/NiO Nanocomposite in Amine-Containing Solutions at the Elevated Temperature
Authors: Kim Seunghyun , Kim Ji Hyun
Published: February 2020

For the development of non-precious-metal-based materials for the assorted electrochemical engineering fields as an alternative for precious metals, we report promising potential of Ni-TiO2/NiO nanocomposite which is synthesized by self-catalytic reactions on metallic substrates. Microstructure characterization via TEM shows the well-dispersed TiO2 nanoparticles in Ni alloy matrix.

 Electrochemical properties are investigated via linear sweep voltammetry (LSV) in 125, 150, and 175 oC of 15 ppm ethanolamine (ETA) solution (pH25 9.3). LSV were carried out in order to reveal anodic polarization behaviors (Figure 1) to investigate a hydrogen evolution reaction (HER) on catalytic surface.

 The results give while Ni/NiO represents electrocatalytic activity until 125 oC, Ni-TiO2/NiO does until 150 oC. This tendency can be explained by the dissolution of NiO species into Ni2+ ions and TiO2 nanoparticles suppress the corrosion of the Ni frame. Therefore, it can be concluded that the embedded noble and solid nanoparticle can enhance electrocatalytic activity even at the elevated temperatures.

Figure 1
Pt/TiO2-CNX Gas-Diffusion Electrode Used in Electrodeposition of Manganese Dioxide for Saving Energy
Authors: Tang Jing , Meng Huimin
Published: February 2020

We have researched a new Pt/TiO2-CNX gas diffusion electrode which was used as cathode in energy-saving and environmentally friendly electrodeposition of manganese dioxide instead of the traditional cathode. The Pt/TiO2-CNX GDE has high activity and durability. We synthesized Pt/TiO2-CNX catalyst by chemical method and then make the Pt/TiO2-CNX gas diffusion electrode. The Pt/TiO2-CNX GDE is three-layer structure which consists of Pt/TiO2-CNX catalyst layer, carbon paper and gas diffusion layer. The Pt/TiO2-CNX GDE is about 0.6mm. The Pt/TiO2-CNX gas diffusion electrode was used in 30g/dm3 H2SO4 +120g /dm3 MnSO4 at 80°C. The electrolysis was carried out at 0.7 V, showing energy saving drop by 60% comparing to the traditional cathode (Cu). The Pt/TiO2-CNx GDE as cathode can save energy about `60% more than 800 h. The section pictures of Pt/TiO2-CNx GDE have almost no change for 100h, 200h and 400h. And there is no crack on the surface of Pt/TiO2-CNx GDE in 100h, 200h and 400h, however, the surface of Pt/TiO2-CNx GDE has some small cracks in 800h. The Pt/TiO2-CNx GDE has great potential to be used as the cathode in electrodeposition of the MnO2.
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Electropolishing of an Fe-Ni-Co Alloy in Acetic Acid-Perchloric Acid Mixture
Authors: Aksu Yasemin , Erdogan Metehan , Demirci Gökhan , Karakaya Ishak
Published: February 2020

Among Fe-Ni-Co alloys, Kovar (53% Fe-29% Ni-17% Co) designated as ASTM F-15[1], is a well-known glass-sealing alloy. It also is classified as low–expansion alloy [2]. Low expansion is required to avoid internal stresses for applications that involve strong ceramic to metal joining.   

One of the most significant problems in vacuum systems is the outgassing which is the liberation of a gas that was dissolved, trapped, frozen or absorbed in a material. To decrease the outgassing rate from the chamber walls, the material should have smooth and passivated surface finish [3]. Electropolishing, one of the finishing methods applied to decrease surface roughness, is appropriate for the systems involving parts of simple and complex geometries. However, there is very limited information on the electropolishing of Kovar alloy in the literature.

Acetic acid (glacial)–perchloric acid (60%) mixture, stated as a cleaning solution before soldering Kovar [4], was used as electropolishing electrolyte in this work. A systematic study was conducted in 5 to 15% perchloric acid containing electrolytes at 25 to 35°C to find the optimum polishing conditions. A two–electrode setup employing Kovar anode and stainless steel cathode was used to perform voltammetric studies to determine low and high levels of current densities. According to linear sweep voltammetry results, shown in Figure 1, 200 to 600 mA/cm2current density range was selected to optimize electropolishing. Experimental route was designed using three parameters (current density, concentration and temperature) and three levels. The duration was kept constant as 5 minutes. Effect of electropolishing duration was determined by utilizing the condition that revealed the lowest roughness in 5 minutes. It was found that, the surface roughness of Kovar samples (having dimensions of 10×25×2 mm), was decreased from 0.21µm to 0.06 µmRa in a 15% perchloric acid containing solution.

 ADDIN EN.REFLIST 1.  ASTMInternational, Standard Specification for Iron-Nickel-Cobalt Sealing Alloy. 2009.

2.  Special-Purpose Nickel Alloys, in ASM Specialty Handbook: Nickel, Cobalt, and Their Alloys. 2000, ASM International. p. 92-101.

3.  Tajiri, K., Pit-free electropolishing of aluminum and its application for process chamber. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1998. 16(3): p. 1196.

4.  Vianco, P.T., F.M. Hosking, and J.A. Rejent, Solderability Testing of Kovar with 60Sn-40Pb Solder and Organic Fluxes, in 19th International AWS Brazing and Soldering Conference. 1988: New Orleans, LA.

Figure 1
Electrochemical Mineralization of Synthetic Human Urine and Simultaneous H2 generation from an Electrolysis Cell Containing a Ni(II)Cyclam-Modified Nanoparticulate TiO2 Anode and a Pt Cathode
Authors: Munguía-Galván Silvia Viridiana-Aideé , Murcio-Hernández Saacnhitee , Pérez-Segura Tzayam , Gutiérrez-Granados Silvia , Carreño Gilberto , Perez J. J. , Espejel-Ayala Fabricio , Rodríguez-García Adrián , Manríquez Juan
Published: February 2020

In this project we studied the electrochemical mineralization of synthetic human urine contained in alkaline aqueous solution by means of Ni(II)cyclam-modified nanoparticulate TiO2 films (OTE/TiO2/Ni-cyclam, where an optically transparent electrode OTE was utilized as conductive substrate) and the simultaneous electrogeneration of H2 via H2O reduction on Pt cathodes; both inserted in an electrolytic cell. Comparative results were obtained from the same setup where an anode without TiO2 (OTE/Ni-cyclam) was alternatively inserted in the electrolysis cell. Electrolysis experiments were carried out for 2h by applying 1.0V vs. NHE to the OTE/TiO2/Ni-cyclam or OTE/Ni-cyclam anodes, where the urea oxidation was predominantly taking place, while the H2 was continuously evolved from the Pt cathode. During this period of time, urine mineralization and H2 production were followed by measuring at the same time: the decrement of the total organic carbon (TOC) in the electrolytic solution and the H2 evolved from the cell. Our results revealed that the H2 evolution proceeds on Pt cathode when the mineralization of urea contained in urine achieves efficiencies of 53 and 36% on OTE/TiO2/Ni-cyclam and OTE/Ni-cyclam electrodes, respectively. Furthermore, it was also observed that urea electrolysis on the OTE/TiO2/Ni-cyclam anodes occurs without interference of parasitic reactions, which could be promoted from other chemical components of the synthetic urine (i.e. chloride ions oxidation for producing hypochlorite ions); thus suggesting that the combination of Ni-cyclam with TiO2 is essential for inhibiting secondary electron transfer processes. These results demonstrate that the OTE/TiO2/Ni-cyclam electrodes could be considered as a promising electrochemical technology for aiding to the treatment of wastewaters containing real human urine, which can be accomplished by H2 generation.
Study of the Influence of the Operational Parameters on the Photo-Electro-Fenton Performance of an Industrial Waste-Water Treatment Prototype
Authors: Robles Irma , Godinez Mora-Tovar Luis Arturo
Published: February 2020

A design of experiments (DOE) was used to characterize the influence of the operational parameters of an industrial prototype for waste-water treatment that was designed and built to operate using the Photo-Electro-Fenton technology. Since the approach under study is based on the photo-assisted Fenton reaction, which in turn is based on the production of hydroxyl radical species via electro-generated hydrogen peroxide (H2O2) and iron ions (Fe2+), the reaction was carried out in a prototype conceived in two reactor chambers. While in the first chamber hydrogen peroxide (H2O2) is produced via oxygen reduction using carbon cloth electrodes, the aqueous solution passes to a second chamber containing an iron-loaded resin in which a UV lamp promotes not only the oxidant species production but also iron reduction.

The performance of the industrial prototype was followed by the absorbance decrease of a commercial dye aqueous solution ( (4-(2-Hydroxy-1-naphthylazo) benzene sulfonic acid, sodium salt, ≥98.0%) considering the applied current, the amount of iron-loaded resin, the flow rate and the pH as the operational variables to be characterized and eventually optimized for the operation of the prototype. In this way, a 24 factorial design was considered with two levels for each variable, central points and duplicate and randomized experiments.  Variable interactions from the DOE were assessed using variance analysis and parameter estimation (ANOVA) using the statistical software JMP 7.0.2, SAS Institute Incorporated. The results revealed that the interactions for which the Prob >ltl being 0.05 or less are those corresponding to pH, resin and the pH-current-resin interaction parameters. From this information and the corresponding analysis it was possible to obtain an empirical equation that describes the reactor´s performance, along with a series of surface response curves that provide information on the relationship of the different operational variables that control the generation of oxidant species and the performance of the prototype under study.
Nickel and Gold Coatings of Germanium and Kovar Substrates
Authors: Karakaya Ishak , Cetin Yasin , Demirci Gökhan , Erdogan Metehan
Published: February 2020

The integration of germanium to other materials such as Kovar®(registered trademark of Carpenter Technology Corporation), an Fe-Ni-Co alloy, by soldering requires a surface preparation due to poor wetting characteristics of germanium. Coating (metallization) by successive electroplating of 3 mm wide nickel and gold frames well adhered to the outer edge of a circular germanium window and kovar body was applied to attain successful joining of germanium to kovar.

Surface cleaning of parts to be joined or plated plays an important role in the quality of the depositions. HF and HCl solutions were used for germanium surface cleaning and the results showed that HF solution was more effective than HCl in terms of removing oxide capability. The desired small grain sized solderable nickel layer was achieved by pulse plating from Watts solution. Likewise, non-porous very thin gold was deposited by pulse plating again and it prevented the diffusion of oxygen to nickel and diffusion of nickel to the free surface. Characterization of the coatings were performed in terms of microstructure, roughness and elemental analysis by scanning electron microscopy (SEM), white light interferometry and x-ray photoelectron spectroscopy (XPS), respectively.
(Invited) Engineering Interfaces for Added Functionality of Nanoelectronics
Authors: Hacker Christina A. , Pookpanratana Sujitra , Jang Hyuk-Jae , Richter Curt A.
Published: February 2020

Future electronic components will be vastly different in response to two critical technical drivers; the increasing complexity to make smaller, faster high performance components and the “electronics everywhere” phenomena requiring portable, low power, niche roles of electronic components.  New materials, devices, and architectures are actively being explored to meet these demands.  A common theme among these approaches is the need for fundamental innovations and understanding of electronic processes at interfaces.  I will describe advances made to manipulate and measure organic and molecular interfaces at the nanometer scale and the impact on the resulting electronic performance.  In particular, I will focus on the measurement advances made in molecular electronics, highlighting our understanding of the science and characterization of the critical buried interfaces.  This talk will contain two illustrative case studies demonstrating the impact of interface engineering on charge trapping memory devices and spin-based paradigms.

Organic molecules are advantageous for trapped charge memory devices due to their small size, discrete nature, and tunability.  Moreover, because each molecule can trap one (and sometimes more) charges, they enable very large trapped charge densities.  I will describe a series of advances in creating and characterizing molecular memory devices incorporating a novel ruthenium based redox-active molecule as the charge storage layer.(1)  

Spin-based paradigms are increasingly important for future electronics. Of special interest is the manipulation of spin in organic materials.  I will describe a series of advances that examine the impact of organic monolayers on the ferromagnetic cobalt and cobalt oxide interfaces and the role interface engineering can play in organic spintronics.(2,3)

1.      
“Non-volatile memory devices with redox-active diruthenium molecular compound”  S. Pookpanratana, H. Zhu, E. G. Bittle, S. Natoli, T. Ren, D. J. Gundlach, C. A. Richter, Q. Li, and C. A. Hacker J. Phys. Chem.: Condens. Matter, a special issue on “Molecular functionalization of surfaces for device applications” (invited)  Oct 2015 accepted

2.      
“Modifying spin injection characteristics of Co/Alq3 system by using a molecular self-assembled monolayer”,  Hyuk-Jae Jang, J.-S Lee, S. J. Pookpanratana, I. C. Tran, C. A. Hacker, and C. A. Richter, J. Phys. Chem. C 119, 12949 (2015)

3.      

“Self-Assembled Monolayers Impact Cobalt Interfacial Structure in NanoElectronic Junctions” 

S. Pookpanratana, L. K. Lydecker, C. A. Richter, and C. A. Hacker,
J. Phys. Chem. C, 119(12), 6687-6695 (Mar 2105)
(Invited) Challenges and Solutions for Future Internet-of-Things Semiconductor Technologies
Authors: Schaeffer Jamie K.
Published: February 2020

Emerging IoT edge-node applications demand new capabilities from semiconductor technologies including unparalleled energy efficiency, reduced package form factor via increased integration, wireless connectivity across a range of low-power wireless protocols, embedded memory for operating systems with smaller footprint and longer battery life, and low cost.  This talk will detail the salient features of 22FDXTM technology, the industry’s first 22nm fully-depleted silicon-on-insulator technology, which give designers the tools to satisfy these challenging requirements. 

22FDXTM has capabilities to meet the low-static leakage requirements of edge-node MCUs with low duty-cycles and low-static leakage and the performance and low active power requirements of wearable application processors.  This is accomplished via a next generation FDSOI transistor architecture, a novel body-biasing capability to dynamically adjust threshold voltages, and a wide-range of Vt options to achieve over 50% total power reduction compared to 28nm and device leakages as low as 1pA/um.  To meet the low-cost requirements of IoT, 22FDXTM was architected to minimize costly double patterning steps while maximizing the overall die shrink.  Over 40% area reduction relative to 28nm is observed in an ARM A9 Neon core.  In addition, the overall BoM and package form factors can be reduced to lower system costs by integrating RF functionality.  To satisfy the wireless connectivity requirements, 22FDX provides an IP offering that satisfies a range of low-power wireless protocols such as WiFi, Bluetooth®, and ZigBeeTM and interface network IPs useful for IoT applications.  Finally, next generation embedded memories, such as MRAM, could be an energy efficient solution that will provide advances to system designs. 

22FDXTM is the right solution to meet the requirements of emerging IoT applications.