bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanocomposites of Metal Oxide@Graphene@Ni Foam for Energy Storage Applications
Authors: Shim Jae-Jin , Sahoo Sumanta , Nguyen Van Hoa , Hwang Jinho
Published: February 2020

Nanocomposites of metal oxide@graphene@Ni foam have been developed for energy storage applications such as supercapacitors. Electrochemical performance of the graphene-based metal compounds nanocomposites has been improved due to the synergistic effect of excellent conductivities and mechanical properties of graphene sheets and the high pseudocapacitance of metal oxides and metal sulfides. Most metal oxides and sulfides are low costs and doping of graphene with metal oxide or sulfide nanoparticles enhances the energy density remarkably, resulting in an excellent performance as an electrode material for supercapacitors. Recently, metal foam has been getting tremendous attention as it provide a large surface area and large pores that enables electrolytes and charges penetrates freely. However, to meet the demands of industry for higher capacitance, energy density and power density, a new approach is required.

Various metal oxides and sulfides will be compared. The benefits of using graphene will also be discussed. In the synthesis of these materials, a cleaner technology has been employed. Nanocomposites that show high surface areas, high conductivities, and remarkable electrochemical properties will be introduced and, especially, materials for high performance supercapacitors will be presented for future energy storage application.
Scalable Study on Nanostructured Carbon –Sulfur Composite Electrodes for High Energy Lithium Sulfur (Li-S) Battery
Authors: Tripathi Balram , Martinez Monika Lopez Victoria , Katiyar Rajesh Kumar , Sharma K.B. , Katiyar Ram S
Published: February 2020

Sulfur is a promising cathode material for lithium sulfur batteries due to its high theoretical capacity (1675 mAh/g). Sulfur cathodes generally suﬀers from fast capacity degradation and poor Coulombic eﬃciency originated from the dissolution of intermediate discharge products (polysulﬁdes, Li2S) in the electrolyte. The polysulﬁde dissolution causes loss of active sulfur and suppresses its deep lithiation, which becomes especially severe during slow charge−discharge processes and deteriorates the electrochemical performances at low cycling rates. Here we report a scalable study on nanostructured carbon-sulfur (S1-x Cx where x=.50,& .40 etc.) composites as a cathode fabricated by ballmiling technique for lithium sulfur battery. To enhance the electrochemical performance of lithium- sulfur battery, carbon black as a conductive material has been dispersed in sulfur. The initial characterization of these nanostructured composites have been performed by XRD, SEM and RAMAN spectroscopy. For electrochemical performance coin cells have been fabricated and are under testing for charge/discharge charcteristics by SOLATRON.

Figure 1
Characterizing Li-Ion Batteries Using in Situ MRI
Authors: Ilott Andrew , Mohammadi Mohaddese , Chang Hee Jung , Grey Clare P. , Jerschow Alexej
Published: February 2020

We will describe our work on the development of techniques for assessing Li-ion batteries and battery materials via magnetic resonance imaging (MRI). The goal of these studies is to analyze battery degradation and energy storage mechanisms in situby imaging changes in both the electrolyte and the electrodes in a noninvasive fashion while a cell is charged or discharged.

We will discuss recent breakthroughs we have made in performing MRI experiments on commercial pouch and coin cell batteries that allow diagnostic tests to be obtained without disassembling the cells. These tests can be run in situ or ex situ and can be used to indicate cycling properties of new battery components, to give a ‘fingerprint’ of manufactured cells for comparison and quality control purposes, or to offer engineering insights into the physical properties of the battery.

We will also report on specific applications of MRI in functioning lithium metal batteries [1], where the technique can be used to correlate the behavior of the electrolyte concentration gradient to the type and rate of dendrite growth on the surface of the Li metal electrode. These studies have confirmed the existence of separate growth mechanisms in different charging regimes. The methodology is extremely sensitive to Li dendrite formation, opening the possibility of testing a broad range of materials and operating conditions to understand when dendrites grow and how they can be prevented.

By developing a detailed understanding of the impact lithium dendrites have on their surroundings, we have been able to design fast 1H MRI experiments that are extremely sensitive to local dendrite growth [2]. The experiments allow for the 3D structure of the dendrites to be reconstructed, and are fast enough to capture the dendrite growth in real time, shedding light on the growth behavior, rate and morphology of the structures formed. Moreover, through simulations and a detailed analysis of the results obtained, we show how the MRI can be used to quantify the volume of dendrites grown.

1. Chang, H. J.; Ilott, A. J.; Trease, N. M.; Mohammadi, M.; Jerschow, A.; Grey, C. P. J. Am. Chem. Soc.
2015, 137(48), 15209–15216.

2. Ilott, A. J.; Mohammadi, M.; Chang, H. J.; Grey, C. P.; Jerschow; Proc. Natl. Acad. Sci.
2016
113 (39), 10779–10784.

Figure caption: Regions of microscopic lithium dendrites that have grown between two lithium metal electrodes. The image is reconstructed from a 15 minute 1H MRI scan.

Figure 1
Nonequilibrium Thermodynamics of Rate-Capacity Lost Phenomena for Lithium-Ion Battery
Authors: Chen Hongjiang , Huang Hsiao-Ying Shadow
Published: February 2020

Current prototypes of lithium-ion batteries lose capacity at high C-rate cycling. It is one of the paramount obstacles hindering many potential emerging technologies ranging from power tools and portable electronics to recent PHEV/EV. Recent studies show that electrodes’ stresses and deformations play a significant role in rate-capacity loss, suggesting that coupling effects exist between the mechanical energy, electrochemical transport process, and electrical potential and capacity. Current available models capturing such coupling effects are developed for specific cases, however. Such as models with idealized geometries, linear deformation or isotropic material properties, resulting the irreversible capacity loss found in experiments was inaccurately described. In this study, nonequilibrium thermodynamics and field equations are incorporated, in which nonlinear deformation and anisotropy material properties are included in the model. With that, one could systematically analyze and investigate phenomena between stress-induced rate capacity fade, phase transformation of anisotropic crystal cathodes, and large deformation on alloy anode for Li-ion batteries. The developed model can be embedded into finite element analysis algorithms to provide a design tool for nanostructure optimization. This research will help understand more details on electrodes’ mechanical behaviors, their influences on transport process in electrodes, and strategies for improving batteries’ high C-rate performance and supplying better lifetime management.
(Invited) Endohedral Single Molecule Magnets
Authors: Greber Thomas
Published: February 2020

It took a while to discover the first endohedral single molecule magnet. In 2012 it was shown that DySc2N@C80 has, at a temperature of 2 K, magnetic relaxation times longer than 104 s [1]. The Figure depicts an image of this molecule, where the Jz =15/2 groundsate of the Dy 4f9 shell is colored in red. This anisotropic electronic ground state is oriented and stabilized by the strong ligand field, mainly of the central nitrogen ion, which causes the single ion magnetism. After DySc2N@C80 a series of new endofullerene single molecule magnets with a variety of different magnetic ground states were reported. For example, one, two or three encaged Dy ions display tunneling of the magnetisation, long remanence, or a frustrated ground state, which indicates a strong magnetic interaction within the cage [2].

I will discuss x-ray magnetic circular dichroism (XMCD) as a particularly sensitive tool for the detection of the magnetism inside the carbon cages and how these experiments may be complemented with superconducting quantum interference device (SQUID) measurements down to 400 mK temperature.

It will furthermore be shown that endohedral units may get preferentially oriented on surfaces [3], and that this proves the carbon cages to be "leaky Faraday cages", with tunable interaction across the carbon shell.

References:

[1] An Endohedral Single-Molecule Magnet with Long Relaxation Times: DySc2N@C80, Westerström et al. J. Am. Chem. Soc. 134 (2012) 9840.

[2] Tunneling, remanence, and frustration in dysprosium-based endohedral single-molecule magnets, Westerström et al. Phys. Rev. B 9 (2014) 060406.

[3] Surface Aligned Magnetic Moments and Hysteresis of an Endohedral Single-Molecule Magnet on a Metal, Westerström et al. Phys. Rev. Lett. 114 (2015) 087201.

Figure: Model of the first endohedral single molecule magnet: DySc2N@C80 (see: www. spinshuttle.ch, courthesy Ari Seitsonen).

Figure 1
(Invited) High Pressure Measurements of Two Polymorphs of C60
.2S8
Authors: Olmstead Marilyn M. , Ghiassi Kamran B. , Beavers Christine M.
Published: February 2020

We recently reported the occurrence and crystal structures of two, concomitant, rotationally disordered polymorphs of C60•2S8 at room temperature, the α- and γ- forms, and their crystal-to crystal transformations to fully ordered polymorphs named β- and δ- C60•2S8, respectively, at low temperatures.1 At 90 K, certain ball---ball centroids of both forms are relatively close, the shortest being 9.881 Å and 9.855 Å, respectively. Polymerization of C60 has received attention over the years in quest of interesting properties. These studies have primarily utilized powdered C60. We were curious to see happens to C60 under high pressure in a crystalline, binary phase such as with S8, and if crystal-to-crystal transformations would occur. Possibly S8would catalyze polymerization and help to prevent fullerene collapse, and orientational ordering would occur. High pressure measurements have been carried out at the Advanced Light Source, Lawrence Berkeley National Lab, and our results will be summarized.

1Ghiassi, et al., Cryst. Growth Des. 2015, 15, 404.
(Invited) Molecular-Scale Evidence Provides New Insights into Fullerene Formation Mechanism
Authors: Feng Lai
Published: February 2020

It has been proposed that the fullerene formation mechanism involves either a top-down or bottom-up pathway. Despite of different starting points, either mechanism approved that particular fullerenes or metallofullerenes are formed through a consecutive stepwise process involving Stone-Wales transformations (SWTs) and C2 insertion or extrusion. However, the formation pathway has been seldom defined at the molecular level due to the missing link fullerenes. Herein, we present a series of previously missing species, including Sc2O@C2v(24107)-C78 and Sc2O@D3h(24109)-C78, Sc2O@C2(7892)-C70 and Sc2C2@D3h(14246)-C74. Each of them can be converted to other isomers or larger or smaller species via a simple conversion route involving Stone-Wales (SW) transformation and C2 insertion or extrusion. Thus, this study might provide molecular structural evidence for the less confirmed fullerene formation mechanism.
(Invited) Isolation and Structural Characterization of Lu2C2n
Authors: Shen Wangqiang , Lu Xing
Published: February 2020

Endohedral metallofullerenes (EMFs) with a composition of M2C2n may exist as di-EMFs, M2@C2n, or as carbide cluster metallofullerenes (CCMFs), M2C2@C2n-2. Although metals with a small ionic radius such as scandium were found to form cluster EMFs and some have been incorrectly assigned as conventional EMFs.[1-3] , Lu-containing EMFs remain largely unexplored in spite that lutecium has a similar ionic radius to that of scandium. In this work, we report the isolation and single-crystal X-ray crystallographic characterization of several unprecedented Lu- containing EMFs: Lu2@C2n (2n=82, 84, 86) EMFs. Theoretical results demonstrate that four electrons are transferred from the two divalent Lu ions onto the fullerene cages.

References：

(1) Lu, X.; Akasaka, T.; Nagase, S. Acc. Chem. Res.
2013, 46 (7), 1627.

(2) Lu, X.; Feng, L.; Akasaka, T.; Nagase, S. Chem. Soc. Rev.
2012, 41 (23), 7723.

(3) Popov, A.; Yang, S.; Dunsch, L. Chem. Rev.
2013, 113, 5989-6113.
(Invited) Molecular Recognition and Assembly of Fullerene and Carbon-Based Materials with Biomolecules
Authors: Osuna Sílvia , Garcia-Borràs Marc , Feixas Ferran , Atienza Carmen , Martín Nazario , Echegoyen Luis
Published: February 2020

Fullerenes and related carbon-based compounds have shown several promising biological applications, mainly due to their ability to be extensively functionalized.[1]

The development of nanohybrid materials combining biological entities and carbon-based materials such as SWCNTs is a cutting-edge area with high impact in fields such as medicine, and energy production.[2] This can be achieved thanks to the favorable recognition and assembly of fullerene and related compounds with proteins. An example of this recognition process is given by the recent finding of some (metallo)fullerene derivatives that were found to exhibit strong anti-viral activity on the replication of HIV-1 in human cells.[3] Although the mechanism of action is not known, it was suggested to be HIV-1 protease independent. The dynamic nature of processes such as assembly, or biomolecular recognition cannot be captured in detail using experimental techniques, and thus computations can provide dramatic new insights. In this talk, a dynamic view of such important biological processes will be presented with an special emphasis on the nanohybrid formation and HIV-1 maturation inhibition.

[1] Garcia-Borràs, M.; Osuna, S.; Swart, M.; Luis, J. M.; Solà, M., Chem. Soc. Rev.
2014, 43, 5089

[2] Mejias, S. H.; Lopez-Andarias, J.; Sakurai, T.; Yoneda, S.; Erazo, K. P.; Seki, S.; Atienza, C.; Martín, N.; Cortajarena, A. L. Chem. Sci.
2016, 7, 4842

[3] Martinez, Z. S.; Castro, E.; Seong, C.-S.; Ceirón, M. R.; Echegoyen, L.; Llano, M. Antimicrob. Agents Chemother.
2016, DOI: 10.1128/AAC.00341-16
Experimental and Theoretical Investigation on the Molecular Structures of Pr@C72, Pr2@C72 and and Their Functionalized Adducts
Authors: Zhao Yanli , Yu Haitao , Lian Yongfu
Published: February 2020

A novel Pr-based mono-metallofullerene derivative, Pr@C72(C6H3Cl2), was successfully prepared and isolated and its molecular structure was verified as Pr@C2(10612)-C72(C6H3Cl2) by combined UV-visible-near-infrared absorption spectroscopy and quantum mechanics characterization, as well as a comparison with the structurally characterized analogue La@C72(C6H3Cl2). Furthermore, an additional computation indicated that the pristine Pr@C72 has the lowest-lying structure as Pr@C2(10612)-C72, followed by Pr@C2v(11188)-C72, which lies only 0.62 kcal mol-1 above Pr@C2(10612)-C72. The charge transfer and orbital interaction between the endohedral Pr atom and the carbon cage as well as the electronic configuration and formal charge state of the encapsulated Pr atom temperature dependence of their thermodynamic distribution was also estimated based on the computed quantum mechanics data.

The pristine endohedral d-imetallofullerene Pr2@C72 was prepared and isolated [2]. Its structure was determined to be Pr2@D2(10611)-C72 by a combination of mass spectrometry, UV-visible-near-infrared absorption spectroscopy, and quantum mechanics characterization. Moreover, the reactivity of Pr2@D2(10611)-C72 was probed by 2-adamantane-2,3-[3H]-diazirine functionalization, and the resulting adducts were identified with mass spectrometry and high performance liquid chromatography. Additionally, the preferred addition positions and isomeric structures of the dominant mono-adduct Pr2@C72(Ad) were further investigated using density functional theory.

References

[1] Y. Zhao, Q. Zhou, Y. Lian and H. Yu. RSC Adv., 2015, 5, 97568.

[2] Y. Zhao, H. Yu, and Y. Lian. RSC Adv., 2016, 6, 115113.
Photoactive Anti-Cancer Nanovectors
Authors: Cunin Frederique
Published: February 2020

The application of nanotechnologies into medicine promises to offer solutions when applied to health challenges such as cancer. In particular the development of new local and focal therapies such as photodynamic therapy will reduce side effects associated with systemic administration of chemotherapy drugs, and will allow preservation or limited resection of organs with small size tumors. Our research projects aim to develop biodegradable anti-cancer materials based on biodegradable porous silicon-based nanostructures to be used for local cancer treatment.

Porous silicon (pSi) nanostructures are fully biodegradable, and nontoxic in vivo. The primary biodegradation product of pSi is orthosilicic acid, which is the bioavailable form of silicon. PSi is easily prepared by electrochemical etching of crystalline silicon. Chemical modification provides a means to adjust the degradation rate of pSi, as well as to load drugs or photosensitizers. Due to their electronic semiconductor-derived properties, pSi nanostructures exhibit intrinsic photoluminescence amenable for imaging. Moreover, they can be excited by near infrared (NIR) two photon excitation light offering possibilities for phototherapies, and for light triggered and targeted treatment, based on tissue-penetrable NIR light response.

The development of photoactive pSi nanostructures functionalized with porphyrins for applications in imaging and photo-activated therapies will be presented.
Redox-Responsive Dimerization in a Ferrocene-Ureidopyrimidinone Supramolecular Assembly
Authors: Smith Diane K. , Cedano Mario
Published: February 2020

One of the important goals in supramolecular chemistry is the development of stimuli-responsive systems, where the strength of the intermolecular interactions can be altered by external signals such as changes in light, temperature, pH, or voltage of an electrode. Applications include self-healing polymers and gels, controlled release of entrapped molecules, and smart materials. In this paper, the results of our electrochemical studies with a ferrocene-containing ureidopyrimidone (UPy) will be described. The UPy system, introduced by Meijer, can form two self-complementary 4 H-bond arrays (AADD or ADAD) which dimerize in relatively non-polar solvents. By attaching an electroactive ferrocene, it may be possible to control the strength of interaction to create a redox-responsive UPy. Following earlier studies by Graham and co-workers, we have prepared a UPy with a ferrocene on the pyrimidinone side, UPy(Fc). Concentration and scan-rate-dependent cyclic voltammetric studies indicate a square scheme type mechanism in methylene chloride. In the starting ferrocene state, the AADD dimer is preferred. Oxidation to UPy(Fc+) results in conversion to another form with a less positive E1/2. Preference for this new form increases at lower concentrations suggesting that it is a monomeric species, which would indicate that oxidation breaks apart the dimer as desired. Alternatively it is possible that the observed concentration dependence results from rate-limiting dissociation of the dimer, but the monomer then tautomerizes to the ADAD form which re-dimerizes. To distinguish between these possibilities, the relative diffusion coefficients (D’s) of UPy(Fc+) to UPy(Fc) were measured by steady-state voltammetry at a microdisk electrode and compared to the relative D’s of ferrocenium to ferrocene. The results of these studies support the conclusion that UPy(Fc+) is monomeric at mM concentrations in methylene chloride, meaning that oxidation of the UPy(Fc) does break apart the dimer. Furthermore, the process appears to be completely reversible. Currently, CV simulations are being performed to determine if this mechanism can quantitatively explain the observed voltammetry. In addition, the synthesis of covalently linked UPy(Fc) oligomers is being initiated, with the goal of creating a redox-responsive supramolecular polymer using this system. Results from these on-going studies will also be reported.
Phthalocyanine in Bulk Heterojunction, Perovskites and Dye Sensitized Solar Cells
Authors: Sastre-Santos Ángela
Published: February 2020

Phthalocyanines (Pcs) are outstanding dye candidates in for dye sensitized solar cells (DSSCs) due to their high extinction coefficient in the visible and near-infrared spectral region and to their high thermal and chemical stabilities[1]. Pcs incorporated in DSSCs have achieved PCEs as high as 6.4 %[2], still far away from the 12.75% PCE obtained by porphyrins, their closest relatives. An elegant strategy to improve the light-harvesting ability of the Pcs is the extension of the aromatic structure by generation aromatic-fused analogues of Pc having a red-shifted absorption. The same strategy will be also tested in perovskite solar cells (PSCs) as electron donor systems.

Herein, we will report our more recent results related with the synthesis of different unsymmetrically substituted phthalocyanines fully conjugated with electroactive systems[3] and the improvement in efficiency of DSSCs and PSCs[4].

Acknowledgements. This work has been supported by the Spanish Ministerio de Economía y Competitividad (Mineco) CTQ-2014-55798-R.

References

L. Martín-Gomis, F. Fernández-Lázaro, Á. Sastre-Santos, J. Mater.
Chem. A  2014, 2, 15672-15682. 

(a) T. Ikeuchi, H. Nomoto, N. Masaki, M. J. Griffith, S. Mori, M. Kimura, Chem.
Commun.
2014, 50, 1941-1943. (b) M. E. Ragoussi, J.-H. Yum, A. K. Chandiran, M. Ince, G. de la Torre, M. Grätzel, M. K. Nazeeruddin, T. Torres, Chem.
Phys.Chem.
2014, 15, 1033-1036.

V. M. Blas-Ferrando, J. Ortiz, V. González-Pedro, R. S. Sánchez, I. Mora-Seró F. Fernández-Lázaro, Á. Sastre-Santos, Adv. Funct. Mater.
2015, 25, 3220-3226. (b) V. M. Blas-Ferrando, J. Ortiz, V. González-Pedro, R. S. Sánchez, I. Mora-Seró F. Fernández-Lázaro, Á. Sastre-Santos, Chem. Commun.
2015, 5, 4785-4793. (c) D. Molina, M. E. El-Khouly, M. El-Kemary, S. Fukuzumi, F. Fernández-Lázaro, Á. Sastre-Santos Chem. Eur. J.
2016, 22,17800 –17807.(a)

(a) D. Molina, C. Parejo, J.C. Álvarez, L. Martín-Gomis, F. Fernández-Lázaro, Á. Sastre-Santos, in preparation. (b) J. Follana, M. M. León, L. Martín-Gomis, F. Fernández-Lázaro, Á. Sastre-Santos, in preparation.
Protection of Aluminium in Acidic Environment and Inhibition Efficiency of Aminophenol-N-Benzylidene -Theoretical and Practical Investigation
Authors: Naik Unnati Jayesh , Shah Nisha K.
Published: February 2020

Aluminium has a remarkable industrial importance. Aluminium and its alloys are exposed to the action of acid in industrial processes where acid play an important role such as oil well acidizing, acid pickling, acid cleaning and descaling. This can lead to substantial metal loss due to corrosion. The use of inhibitors is one of the most practical options to protect metal from corrosion. Organic and inorganic compounds are usually added to HCl as corrosion inhibitors.

The present work is carried out to find the effective inhibitor with minimum concentration but maximum inhibition. The corrosion inhibition effect of o,m,p-Aminophenol-N-Benzylidene (o,m,p-AmphNB) for pure Aluminium in 1M HCl were investigated by means of weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Electrochemical studies were carried out using standard three electrode cell where Calomel electrode act as a reference electrode, Platinum electrode as counter electrode and Aluminium electrode as working electrode. The values of ΔGads indicates the competitive Chemisorption and physisorption, Potentiodynamic polarization parameters revealed the mixed mode of inhibition with predominance of cathodic inhibition. The EIS showed linear correlation with concentration of inhibitor & Rctl while Cdl inversely correlated. Quantum chemical calculations based on density functional theory (DFT) method were performed on studied inhibitors to ascertain relationship between molecular structure and their inhibition efficiency. Correlation analyses between experimental and theoretical values were performed to conclude that the inhibition effect of inhibitors could be explained in terms of electronic properties.

Figure 1
Corrosion of Austenitic Steels and Their Components in Molten Nacl–Kcl–UCl3
Authors: Abramov Aleksandr V. , Polovov Ilya B. , Dedov Kirill V. , Karpov Vyacheslav V. , Zhilyakov Arkadiy Yu. , Belikov Sergey V. , Volkovich Vladimir A. , Rebrin Oleg I.
Published: February 2020

The fused halides can be used for nuclear fuel reprocessing and as working media for molten salt nuclear reactors. However practical implementation of such technologies is limited by the problem of finding suitable corrosion resistant materials capable of long-term working in contact with molten salts. From the economical point of view the application of stainless steels as construction materials for the molten salt media is one of the most prospective ways.

In the present study the corrosion behaviour of metallic iron, nickel, chromium, molybdenum, AISI 316L and 12Kh18N10T (analogue of AISI 321) austenitic steels was studied in NaCl–KCl–UCl3(1 wt.% U) melts at 750 ºC.

Gravimetric measurements served as a basis for estimating corrosion resistance of studied materials. Quenched melts were analyzed using ICP-AES method. The surface of the alloy samples after corrosion tests was characterised using XRD, SEM and Х-ray microanalysis. The foils of corroded materials were examined by TEM.

The corrosion rates of studied metals in NaCl–KCl–UCl3melt decrease in the following order: Cr>Fe>Ni>Mo, which correlates well with the formal standard potentials of metals in chloride melts indicating electrochemical nature of the corrosion processes. Molybdenum is the only corrosion resistant metal in the uranium-containing chloride melts and it can be used as a construction material for molten salt reactors.

The major products of stainless steel corrosion in chloride melts are iron, chromium and manganese species. The surface of the corroded samples of austenitic stainless steels was depleted in manganese and chromium and enriched in nickel and molybdenum. Intergranular corrosion was observed for all types of austenitic steels. In terms of intensity and depth of the corrosion layer in NaCl–KCl–UCl3 the studied steels can be ranged in the order AISI 321>AISI 316L that correlates with the amount of excessive phases formed (figure).

Figure 1
Role of Hydroxyl Group in Cerium Hydroxycinnamate Compounds in Enhancing the Corrosion Resistance of Mild Steel in Chloride Ion Media
Authors: Nguyen Nam Dang , Phan Ha Thi Ngoc , Nguyen Vu Si Hoai , Vu Thu Thi Hanh , Phan Binh Minh Quoc
Published: February 2020

The role of hydroxyl group in cerium hydroxycinnamate compounds has been studied as an effective corrosion inhibitor for mild steel in 0.6 M chloride solution. The results show that the surfaces of mild steel coupons exposed to solutions containing inhibitors had no signs of corrosion attack due to protective film formation, whereas the surface of mild steel coupons exposed to non-inhibitor containing solutions was severely corroded. Cerium hydroxycinnamate compounds showed as a better inhibitor for AS1020 steel at higher concentration. The addition of Cerium hydroxycinnamate compounds form protective film layer and improves the protective film and charge transfer resistance which plays an importance role in corrosion properties. A high inhibition performance is attributed to the forming protective inhibiting deposits that slow down the electrochemical corrosion reactions. The results also indicated that the position of hydroxyl group in cerium hydroxycinnamate significantly effect to the inhibition performance of mild steel in chloride ion media.
The Effect of Film Thickness and Substrate Resistivity on Corrosion of Fe Thin Films
Authors: Sapiro David , Feng Ruishu , Webler Bryan , Ziomek-Moroz Margaret , Ohodnicki Paul R
Published: February 2020

This study investigated the corrosion behavior of Fe films with different thickness in NaCl solution. It has been reported that nanocrystalline metal thin films are more corrosion resistant than their coarser or bulk counterparts, but the effect of thickness is not well characterized. Polarization curves were measured for three iron thin film with thicknesses of 10, 20, and 100 nm and bulk iron in aerated 3.5 wt% NaCl solution at 24 ˚C. Each film thickness was deposited on silica substrates, and 20 and 100 nm films were also deposited on silica substrates with a Pt conductive layer. The resistivity/conductivity of the samples were measured using four point resistivity measurement, and the effect of film and substrate resistivity on corrosion was addressed by comparing polarization curves of thin films with and without the platinum conduction layer. The extent of film corrosion was spatially varied and the variation in localized electrochemical response was measured using scanning vibrating electrode technique. The corroded films were also characterized by SEM.
Electrochemical Properties of Carbon Steel Corrosion in Boiler Water at Elevated Temperatures
Authors: Hall Derek M. , Caravaggio Michael F. , Shulder Stephen J. , Lvov Serguei N.
Published: February 2020

Water treatment programs are a key factor in steam cycle power station safety. They are one of the first lines of defense against a wide range of corrosion-induced boiler system failures. To further facilitate the development of effective boiler water treatment programs, it is important to fully understand the nuances of the underlying corrosion process. Though waterside corrosion of tubing in steam cycle power stations is an old problem, many aspects of the underlying processes are remain poorly defined at elevated temperatures and pressures. These gaps in our current understanding complicate the development and validation of new corrosion mitigation treatments. Here we demonstrate how a series of electrochemical techniques can be used to fill in some of these gaps when coupled with electrochemical theory and a high temperature & pressure condensed phase corrosion sensor. In this study, we investigated the kinetics of carbon steel corrosion in simulated boiler waters at elevated temperatures and pressures. Electrochemical properties (Tafel slopes and corrosion currents) of the corrosion processes were obtained and compared between techniques such as linear polarization resistance, electrochemical impedance spectroscopy and potentiodynamic scans. These comparisons demonstrated the power of using multiple techniques to better understand the behavior of elevated temperature corrosion. Furthermore they can serve as the benchmarks needed to verify the effectiveness of new water treatment programs.
(Invited) Understanding the Pre-Failure Thermo-Mechanical Issues in Electromigration of TSV Enabled 3D ICs
Authors: Sunday Christopher E , Veksler Dmitry , Cheung K. P. , Obeng Yaw S.
Published: February 2020

Traditional metrology has been unable to adequately address the needs of emerging integrated circuits at the nano scale; thus, new metrology and techniques are needed. For example, the reliability challenges, and their root causes, in TSV enabled 3D-IC fabrication need to be well understood and controlled to enable mass production. This requires new approaches to the metrology. In this paper, we use microwave propagation characteristics (S-parameters) to study the thermo-mechanical reliability issues that precede electromigration failures in Cu-filled TSVs. The pre-failure insertion losses and group delay are reversibly dependent on both the device temperature and the amount of current forced through the devices under test. This is attributed to the plasticity of the copper fill in the TSVs.
Reliability of Post Plasma Oxidation Processed ALD Al2O3/Hf1-xZrxO2 Thin Films on Ge Substrates
Authors: Bhuyian Md Nasir Uddin , Sengupta Arijit , Ding Yiming , Misra Durga , Tapily Kandabara , Clark Robert D. , Consiglio Steven , Wajda Cory S. , Leusink Gert J.
Published: February 2020

Germanium devices are widely investigated due to their high hole and electron mobility compared to that of silicon. Mobility above 300 cm2V-1s-1 has been reported for Ge PMOS. On the other hand, Ge NMOS showed poor drive current and low mobility in previous studies. This poor performance is attributed to the inability to form a good Ge/high-k interface (1). They also exhibit hysteresis during the capacitance voltage (C-V) sweep because of the presence of slow trap states near the dielectric substrate interface (2). Recently, the use of a slot-plane-antenna (SPA) Ar plasma during the deposition of ALD Hf1-xZrxO2 on Si substrate was reported to enhance the EOT (equivalent oxide thickness) downscaling potential with a suppressed trap formation in the bulk oxide under electrical stress (3).

In this work, we have investigated TiN/HfZrO/Al2O3/Ge gate stack using MOS capacitors with six different Zr/(Hf+Zr) content (0%, 25%, 33%, 50%, 75%, and 100%) in the dielectrics. The dielectrics were subjected to SPA plasma oxidation after the deposition process. Electrical characterization of these devices was studied in order to observe the impact of Zr addition in HfO2. The equivalent oxide thickness (EOT), flat-band voltage (VFB), interface state density (Dit), C-V hysteresis, and leakage current (I-V) behavior were analyzed. Figure 1 shows the comparison of EOT and VFB as a function of Zr content in the dielectrics. Figure 2 presents the C-V hysteresis data (to the left axis) and mid gap Dit (to the right axis) for these devices. The addition of Zr in HfO2 was found to enhance the EOT up to 75% Zr incorporation. These devices also showed lower hysteresis in the C-V characteristics. However, A reduction in EOT for these devices showed to increase the flat-band voltage shift (Fig. 1). While devices with 100% Zr showed the highest EOT value coupled with the lowest mid gap Dit, a reduction in EOT with Zr addition in HfO2 moderately increases the Dit (Fig. 2 to the right scale).

Figure Captions:

Fig. 1: Equivalent oxide thickness (filled squares to the right scale) and flat-band voltage (open triangles to the left scale) comparison for the addition of Zr in HfO2.

Fig. 2: Hysteresis behavior extracted from C-V sweep first from accumulation to inversion and then from inversion to accumulation (filled squares to the left scale) and interface state density by conductance method (open circles to the right scale) for ALD Hf1-xZrxO2/Al2O3 gate stacks on Ge substrate.

References:

1. Y. Ding, D. Misra, M. N. Bhuyian, ECS Trans., 69 (5) 313-322 (2015).

2. J. Lin, Y. Y. Gomeniuk, S. Monaghan et al., J. Appl. Phys., 114, 144105 (2013).

3. M. N. Bhuyian, D. Misra, K. Tapily et al., ECS. J. of Solid State Sci. Tech., 3(5) N83 (2014).

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(Invited) Diffusion and Depletion Effects in Chronoamperometry of Diazonium based Electrochemical Grafting
Authors: Hirsch Brandon , Welke Peter , Brown Anton , De Feyter Steven
Published: February 2020

Chemisorption on electrode surfaces by means of electrochemical “grafting” of diazonium based compounds has demonstrated the ability to introduce robust functional character to electrode surfaces, i.e., selective binding and recognition. Unfortunately, chemical decomposition of the active diazonium compounds frequently plagues the extent of surface functionalization. Impacts of diazonium degradation on the grafting process can be limited by activation (diazotization) from stable aniline precursors moments before the electrochemical treatment. In this work, we investigate how kinetic control of this diazotization activation reaction impacts the resultant electrochemical grafting on highly oriented pyrolytic graphite (HOPG) electrode surfaces. Using simple aniline precursors, diazotization reactions are carried out with four different protocols: ex
situ activation, ex situ activation & stirring, in situ activation, and in situ activation & stirring. The resultant HOPG electrode surfaces are analyzed using scanning tunneling microscopy and Raman spectroscopy, to reveal hindered surface functionalization from in situ activation methods. Increases in the already high grafting densities achieved from ex situ diazotization can be enhanced by stirring the solution while applying the electrochemical potential. Stirring is shown to replenish the depletion layer that arises after the electrochemical potential is applied. Overall, this work highlights the role of diffusion, depletion, and electric double layers involved in diazonium based electrochemical grafting processes.
Lithium Recovery from Used Li-Ion Batteries Using Innovative Electrodialysis Method with Lithium Ionic Superconductor
Authors: Hoshino Tsuyoshi
Published: February 2020

In recent years, the industrial importance of lithium (Li) has increased due to its use in Li-ion batteries. For example, large-sized Li-ion batteries are used as power supplies for electric vehicles and for storage of electricity in smart grids and smart houses. Therefore, a large amount of Li is required worldwide. The extraction of Li from used Li-ion batteries would allow a large amount of Li to be inexpensively acquired. The technology for recycling cobalt (Co) and nickel (Ni) from used Li-ion batteries has already been established. On the contrary, the technology for recycling Li from used Li-ion batteries is not yet established.

I have developed a method for the recovery of Li from seawater using a Li ionic superconductor functioning as a Li-ion separation membrane (LISM) [1]. Only Li ions were successfully recovered from seawater through the LISM; other ions in the seawater did not permeate the membrane. Therefore, I have developed an innovative new method for recycling Li from used Li-ion batteries using the LISM.

Figure shows the proposed Li recovery method. This innovative method involves the use of an LISM whereby only Li ions in a solution of used Li-ion batteries permeate from the positive electrode side to the negative electrode side during electrodialysis; the other ions, including Co, Al, and F, do not permeate the membrane. Li0.29La0.57TiO3 was selected as the LISM because it exhibits high durability against water. The positive side of the dialysis cell was filled with used Li-ion battery solution, supplied by DOWA ECO-SYSTEM Co., Ltd., Japan; the Li concentration of the solution was 2543.5 mg/L. Then the negative side was filled with distilled water. The applied dialysis voltage was 5 V, and electrode area was 16 cm2.

The calculation of the Li recovery ratios for this first of a kind electrodialysis technique with an LISM sheet was performed. The Li recovery ratio increased with electrodialysis time, reaching approximately 10% at 72 h of dialysis. The recovery ratios of Co, Al, and F were not calculated because the concentrations of Co, Al, and F were below the detection limit of inductively coupled plasma atomic emission spectrometry (ICP-AES).

After electrodialysis, CO2 gas was bubbled in the Li recovery water to produce lithium carbonate (Li2CO3) as a raw material for Li-ion batteries. The Li2CO3 deposition was easily generated by the reaction of CO2gas and the Li recovery solution as a lithium hydroxide (LiOH) solution.

This new method for recycling Li-ion batteries shows good energy efficiency and is easily scalable. Thus, this electrodialysis method is suitable for the recovery of Li from used Li-ion batteries.

[1] T. Hoshino, Desalination, 359, 59-63  (2015).

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Electrodeposition of Indium and Tin from Molten Chloride Electrolytes
Authors: Haarberg Geir Martin , Qin Bo , Martinez Ana Maria
Published: February 2020

Recycling of electronic waste to recover the metal value is of prime importance, especially for metals with limited resources. An electrochemical approach should be an interesting option to develop sustainable recycling processes.

The electrochemical deposition of tin was studied by using cyclic voltammetry at glassy carbon electrodes in molten LiCl-KCl at 450 ℃. Tin deposition on the glassy carbon electrode was found to be diffusion controlled in molten LiCl-KCl containing 0.1mol% SnCl2. At higher anodic voltage, Sn2+ was oxidised to Sn4+. Metallic tin of high purity was obtained in potentiostatic electrolysis experiments. The current efficiency for deposition of Sn was as high as 95%.

The electrochemical reduction processes in molten LiCl-KCl eutectic containing InCl3, InCl2 and InCl were studied on glassy carbon electrode at 450 °C. The cathodic discharge of indium ions to form metallic indium was shown to take place by a consecutive two-step electrochemical process involving In3+, In+ and metallic In.

Metallic indium was deposited by constant voltage electrolysis in molten LiCl-KCl containing InCl3.

The electrochemical behaviour of ITO (indium oxide combined with 10 percent tin oxide) was studied in molten LiCl-KCl at 450 °C. The direct deoxidation of solid ITO was investigated by using different electrodes such as Mo wire and liquid zinc. An ITO covered glass electrode was investigated by electrochemical means in molten LiCl-KCl at 450 °C using Mo wire current collector. The findings, together with SEM and EDX analyses, confirmed that some ITO had been reduced.
Electrophoretic Deposition of Gadolinium-Doped Ceria As a Barrier Layer on Yttrium-Stabilized Zirconia Electrolyte for Solid Oxide Fuel Cells
Authors: Liu Xingbo , Hu Shanshan , Li Wenyuan
Published: February 2020

Screen-printing or spin-coating are most common methods for deposition of the doped ceria barrier layer between cathodes (LSCF or LSM) and YSZ electrolyte in solid oxide fuel cells. However, it is difficult to achieve fully-dense barrier layer below the reaction temperature, e.g. 1400oC. In this study, a gadolinium-doped ceria (GDC) barrier layer was deposited on the YSZ electrolyte by an economically-efficient, scalable electrophoretic deposition method (EPD). Polypyrrole (PPy) was coated on YSZ surface as the conductive agent. Highly compact GDC green layer was obtained by the EPD process in an ethanol-based suspension. GDC thin layers in a thickness range of 8-10 µm were successfully densified at as low as 1250 oC. The performance of these EPD-deposited cells was evaluated using symmetrical cell configuration through the electrochemical impedance spectroscopy (EIS). In comparison, the ohmic resistance of the GDC barrier layer made by the conventional spin-coating method is reduced through the present EPD method. This result suggests that EPD is a desirable method for efficiently manufacturing electrode barrier layer with improved performance.

Figure 1
Advanced Characterisation Techniques Applied to Battery Materials
Authors: Randjbar Daemi Sohrab , Shearing Paul R.
Published: February 2020

Porous electrodes support a wide range of electrochemical and physical processes and are fundamental to the operation of a variety of battery types. While 1-dimensional models have been accurate in predicting cell performances at low cycling rates, they fail to account for degradation and ageing. These effects are directly relatable to the complex 3-dimensional nature of porous electrodes. Advances in X-ray computed tomography (CT) have allowed for the non-destructive imaging of a broad range of battery materials, with studies ranging from microstructural analysis to in-situ and in-operando characterisation. The availability of a variety of micro- and nano-CT instruments at the Electrochemical Innovations Lab at University College London, offers an unparalleled opportunity to characterize a variety of electrode materials across a range of length-scales, from 10s nm to 10s μm. The focus of this project is subdivided in analysing commercially available battery materials and materials used in next-generation batteries.

Because of the stable electrochemical performance of most commercially available electrodes, the analysis of these materials focuses on understanding how different calendering and manufacturing methods affect the electrode on the micro- and nano- length scales. Metrics such as the particles size and porosity distributions, or transport parameters such as the tortuosity factor are studied. Furthermore these material are used as a model to develop novel sample preparation methods as well novel miniature in-situ cells for X-ray imaging.

A novel laser micro-machining sample preparation method has also been developed. This can produce electrode pillars with diameters below 100 μm whilst maintaining the structure and directionality of the electrode, allowing for a clear identification of microstructural features and changes caused by the calendering process on the electrode. Figure 1 a) shows a virtual slice of a graphite anode micro-machined into a pillar and characterised with combined absorption and phase contrast imaging. Fig 1 b) presents a volume rendering of the graphite pillar along with the copper current collector.

For next-generation battery systems, there is a lack of in-depth microstructural studies that not only analyse and compare different types of electrode structures but also relate how these affect and are affected by battery performance and cycling. To increase the repeatability of the experiments and the representativeness of the obtained datasets, novel sample preparation techniques are developed. These studies have the aim of analysing a material, but also setting the basis for future work in which methods are devised for observing charged and discharged samples in inert and in-situ environments.

Figure 1
Synthesis and Magnetic Characterization of Nanostructured Silicon with Bi-Metal Filling
Authors: Rumpf Klemens , Granitzer Petra , Gonzalez-Rodriguez Roberto , Coffer Jeffery L , Michor Herwig , Poelt Peter
Published: February 2020

The purpose of this work is to combine magnetic nanostructures of two different metals within nanostructured silicon to influence the magnetic switching behavior of the porous silicon/metal nanocomposite. Two routes are used to achieve such nanocomposites. The porous silicon templates are fabricated with a mesoporous morphology offering average pore diameters of 50 nm and these pores are filled with a bi metal filling, namely Ni and Co. The two metals are deposited alternatingly by electrodeposition. A further approach is the chemical growth of Co nanoparticles within porous silicon nanotubes (SiNTs) and the additional deposition of a Ni layer on the outer surface of the tubes (Figure 1). The inner diameter of the silicon tubes is around 50 nm and the wall thickness is about 10 nm. Since the silicon wall of the tubes offers a porous structure the Co particles, which are localized near the pore surface on the wall of a given nanotube, can touch the Ni layer. An alternative structure involves the deposition of an additional Si layer (after the growth of Co particles inside the tubes) as a spacer before the Ni deposition.

These samples have been characterized structurally and magnetically. The magnetic properties of the systems strongly depend on the size and shape of the deposited bi-metal nanostructures and also on the proximity of the Ni and Co structures to each other. If the distance is small enough magnetic exchange coupling between the two metal structures is present. Due to the size of the metal deposits and the coupling of the bi-metal structures the switching behavior of the hysteresis can be tuned. The aim is to achieve self-assembled nanocomposite systems with a high as possible energy product which can be promising for permanent nanomagnets.

Figure 1: SEM image of silicon nanotubes (SiNTs) with Co particles deposited inside the tubes and Ni covering the walls of the tubes.

Figure 1