bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyvinylidene Fluoride Derived Carbon As High Performance Anode Material for Lithium Ion Batteries
Authors: Suresh Mamidi , Gopalakrishna Karthik Mamandur , Sharma Chandra Shekhar
Published: February 2020

Introduction

Polyvinylidene fluoride (PVDF) is a fluoropolymer which consists of vinylidene fluoride as a monomer. Conventionally, it is widely used material in electrode preparation as a binder between active carbon material and the current collector. However in this work, we propose the use of PVDF as a polymer precursor to carbon. In literature, PVDF was used as precursor for carbon with ~20% yield.1 However, this yield was increased to ~70% by dehydrofluorination of PVDF prior to pyrolysis.2,3

In our present work, we first carried out dehydrofluorination followed by pyrolysis at different temperatures (900, 1200 and 1400 ⁰C respectively) to obtain the hard carbon as characterization by field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy. Later, electrochemical performance of these hard carbons pyrolyzed at different pyrolysis temperature was investigated at different current densities.

Experimental Section:

 PVDF powder was dehydrofluorinated in NaOH and Tetra-n-butylammoniumbromide solution. Dehydrofluorinated powder was pyrolyzed in inert atmosphere at different final pyrolysis temperature. Slurry made of this carbon was coated over stainless steel foil and dried for 12 h in a vacuum oven prior to cell packing in argon atmosphere glove box. Electrochemical performance was studied using glavanostat/potentiostat.

Results and discussions:

Figure 1: (a,b) HRTEM images of CDI-1400 at different magnifications; (c) Comparison of cycling behaviour at 0.1 C rate for carbonized samples for different temperature

TEM images (Figure 1a and 1b) clearly reveals that particle size is 290 nm and inside the each spherical particle, there are disordered areas consists of randomly arranged smaller crystallites of graphene. From this, we can conclude that carbon derived from PVDF precursor is a hard carbon.

From Figure 1c, we observe that the sample pyrolyzed at 1400 ⁰C exhibited higher reversible capacity (297 mAh/g) than the other two samples (pyrolyzed at 900 ⁰C and 1200 ⁰C) after 11 cycles of charge-discharge at 0.1 C rate. The coulombic efficiency was found to be more than 94 % after 11 cycles for all three samples. A detailed analysis on dehydroflorination and charge discharge experiments at different current densities will be presented at conference. Cyclic voltammetry and impedance studies will also be presented to support the cyclic stability and capacity retention values.

References:

1. T. Zheng et al.,
Electrochem. Soc.
142, 2581–2590 (1995)

2. Jatuphorn et al., Journal of Metals, Materials and Minerals. 18, 57-62, (2008).

3. Seok-Min Hong et al., RSC Adv.
4
,58956-58963 (2014).

Figure 1
(Invited) Non-IPR Monometallic Clusterfullerenes Entrapping a Nearly Linear Metal Cyanide Cluster
Authors: Yang Shangfeng
Published: February 2020

Fused-pentagon is known to result in an increase of local steric strain according to the isolated pentagon rule (IPR), and for all reported non-IPR clusterfullerenes multiple (two or three) metals are required to stabilize the strained fused-pentagons, making it difficult to access the single-atom properties. In this talk, we present the syntheses and isolations of novel non-IPR monometallic clusterfullerenes MNC@C76 (M=Tb, Y), in which one pair of strained fused-pentagon is stabilized by a monometallic cluster. The molecular structures of MNC@C76 (M=Tb, Y) were determined unambiguously by single crystal X-ray diffraction, featuring a non-IPR C2v
(19138)-C76 cage entrapping a nearly linear MNC cluster, which is remarkably different from the triangular MNC cluster within the reported analogous clusterfullerenes based on IPR-obeying C82 cages. In specific, TbNC@C76 molecule is found to be a field-induced single-molecule magnet (SMM).
(Invited) Use of Support-Free Amines to Isolate Larger Cage Endohedral Metallofullerenes
Authors: Stevenson Steven , Thompson Hannah R. , Kirkhorn Amelia , Budd Sarah K , Kime Brittany L
Published: February 2020

Many publications exist for C80 endohedral metallofullerenes (e.g., M3N@C80), but there is little research on larger metallofullerene cages, such as M3N@C88-C112 and M3C98-C102. Our goal is to isolate these larger endohedrals from complex extracts via chemical selectivity. We seek to replace our earlier use of reactive amines that were immobilized on silica gel. Finding a support-free amine with water-soluble groups would remove the need to synthesize aminosilica and save the expenses of chemicals and time. In this presentation, we discuss the feasibility of using amino alcohols as selective reagents. With this approach, we can either chemically isolate a larger cage endohedral (M3N@C88) or delay the use of HPLC by injecting only highly enriched samples obtained from our chemical purification.
(Invited) Growth of Endohedral Metallofullerenes: The Transformation of Sc3n@D
3-C68 into Sc3n@C80
Authors: Poblet Josep M. , Abella Laura , Rodríguez-Fortea Antonio , Mulet Marc , Dunk Paul W. , Echegoyen Luis
Published: February 2020

Carbon cages that entrap metals were first observed just days after the landmark discovery of C60. The synthesis of Sc3N@C80, which is comprised of a planar Sc3N cluster encapsulated within an icosahedral C80 cage, transformed significantly the field of endohedral metallofullerenes (EMFs). Recently, efficient routes toward arc discharge plasma synthesis of EMFs by vaporization of graphite, metal oxide, and solid nitrogen sources, such as guanidine thocyanate and guanidinium salts, have been developed. However, the origin of EMFs produced by plasma synthesis techniques and any associated formation processes that take place remains still unclear. Here, we report some recent results on the gas-phase synthesis of Sc3N@C2n and particularly on the transformation of the pentalene-containing Sc3N@D
3-C68 compound, which transform through a bottom-up mechanism into Sc3N@C80. We will discuss on potential pathways for the growth of Sc3N@D
3-C68 when it is exposed to an atmosphere of carbon plasma produced from graphite, and on the potential role that heptagonal rings may play.
(Invited) Gas-Phase Self-Assembly of Group III-Based Nitride Clusterfullerenes By Laser Plasma Synthesis
Authors: Dunk Paul W. , Mulet-Gas Marc , Marshall Alan G. , Hendrickson Christopher L. , Castro Edison , Echegoyen Luis , Abella Laura , Rodríguez-Fortea Antonio , Poblet Josep M.
Published: February 2020

The chemical processes that result in self-assembly of nitride clusterfullerenes are largely unknown because in situ experimental studies are not possible by conventional arc plasma discharge techniques. Here, we report the gas-phase formation of Group III-containing nitride clusterfullerenes by laser vaporization of graphite-, metal-, and heteroatom-based starting materials, conducted by online chemical sampling techniques and analyzed by ultrahigh resolution 9.4 tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Further, structurally defined clusterfullerenes are exposed to carbon vapor produced from graphite under characteristic physicochemical synthesis conditions to elucidate cluster-cage and structural effects on nanocarbon reactions that control formation.
Pyrolysis of Self-Assembled Iron Porphyrin Layers on Carbon Black As Core/Shell Structured Electrocatalysts for Highly Efficient Oxygen Reduction in Both Alkaline and Acidic Media
Authors: Song Yujiang
Published: February 2020

Although significant progress has been achieved recently in the field of nonprecious metal electrocatalysts (NPMEs) for oxygen reduction reaction (ORR), yet highly active and durable NPMEs remained rare for dual applications to both alkaline and acidic conditions. In this study, we report simple carbonization of evaporation-induced self-assembled iron(III) porphyrin (FeP) layers uniformly coated on carbon black, leading to an unprecedented core/shell structured NPME composed of multi-layered N-doped graphite uniformly coated on carbon black. The thickness of graphite carbon shell can be readily adjusted up to about 7 nm by varying the amount of FeP loaded on carbon black. Interestingly, the obtained NPME exhibited a high ORR activity in both alkaline (half-wave potential of 0.87 V vs. RHE) and acidic (half-wave potential of 0.75 V vs. RHE) media, which is one of the highest ORR activities of NPMEs in document. In particular, the core/shell structured NPME demonstrated a remarkable durability in acidic conditions suprior to that of commerical Pt/C, which appears to be closely related to the multi-layered graphite shell. It is very likely that after the outermost graphite layer is consumed, the inner one becomes available and thus effectively maintains the original ORR activity. Furthermore, the core/shell NPME displayed nearly direct 4e and indirect 4e process toward ORR in alkaline and acidic media, respectively. This study pointed out a new avenue for the creation of high-performance NPMEs in both alkaline and acidic media by heat-treating self-assembled metallomacrocycles on various substrates, which may have potential applications in proton exchange membrane fuel cells (PEMFCs), metal-air batteries, and electrolyzers.
Hydrogen Generation Catalyzed By Metalloporphyrins
Authors: Hung Chen-Hsiung
Published: February 2020

Hydrogen has potential of being used as the future green fuel in fuel cells. The demand and consumption of hydrogen have predicted to continuously rise in the next two decades. Nevertheless, a highly efficient and low cost of water-splitting catalyst for hydrogen generation remains elusive. In this presentation, we synthesize a series of metalloporphyrin complexes in order to elucidate the effects of porphyrinic structure to the catalytic efficiencies. It is found that the metalloporphyrins with different substituents demonstrated different catalytic activities. A porphyrin with acidic substituents appears to be essential to offer high catalytic efficiencies. Additionally, a substituent located closer to the metal ion center will be better than oriented outward in respect to the central core. Our results also suggest that the type of central metal ions is another factor that control the activity of the hydrogen generation catalysts. Through the comparison on the CV of two novel N-confused porphyrin cobalt nitrosyl complexes, it appears that the activities of the catalysts depend on the reduction sites where the reducing equivalent will reside, i.e. a Co(NO) moiety based reduction has a more positive onset potential than a porphyrin-based reduction.
Template Effects of Tetrakis(thiadiazole)Porphyrazine to the Structures of Phthalocyanine Thin Films
Authors: Awaga Kunio , Eguchi Keitaro , Heutz Sandrine
Published: February 2020

Molecular templating is an attractive method to improve the crystallinity of organic thin films and control the molecular orientations in them. Here, we report on the templating effects of an organic n-type semiconductor, tetrakis(thiadiazole)porphyrazine (H2TTDPz), on the structure and optical absorption of a p-type semiconductor, copper phthalocyanine (CuPc). X-ray diffraction measurements for the double layer thin films, CuPc/H2TTDPz, indicate a flat-on structure of CuPc, which is copied by the structure of the H2TTDPz thin films, in spite of that the CuPc thin films usually form edge-on type thin films. The optical absorption measurements show new low-energy transitions in the templated CuPc films.
Functionalized Luciferins for Applications in Supramolecular Chemistry: In Vivo Light Switches
Authors: Rahn Harrison P , Jayawickramarajah Janarthanan
Published: February 2020

Sensing of supramolecular assembly in vivo has been a struggle for current research because a limited number of assays can probe this effectively. Firefly luciferin has been widely used as an in vivo reporter of adenosine triphosphate, magnesium cations, and esterase activity because of its highly selective enzyme catalysis and high quantum yield when oxidized in the presence of adenosine triphosphate and magnesium cations. The emitted photon is of a yellow-green color thus detection has been possible in vivo from cells to mammals by a simple luminescence assay. Caging, or rendering the firefly luciferin molecule incompatible for luciferase enzyme, has been accomplished most commonly by appending electron withdrawing groups to the 6’-hydroxyl position or esterification of the thiazole moiety. The caged luciferin then undergoes a reaction to yield its native form, resulting in emission of a photon upon oxidation and reporting the desired reaction or process. The goal of our research is to use firefly luciferin as a reporter of supramolecular assembly by a novel method of caging, reversibly with a host molecule (cyclodextrins and cucurbiturils). This talk will describe the synthesis and characterization of a novel set of firefly luciferin derivatives for use in the luciferin-luciferase type assays with the goal of detecting host-guest interactions. This talk will illustrate how supramolecular assembly and its predictability can be used to design novel biocompatible systems to overcome the challenges of a highly competitive cellular environment.
Hexaphenylbenzene and Hexabenzocoronene Porphyrin Conjugates
Authors: Jux Norbert , Lungerich Dominik , Martin Max
Published: February 2020

We will present the synthesis, characterization, and properties of some novel hexaphenylbenzene-substituted porphyrins. The oxidation to hexabenzocoronene conjugates will be discussed as well.[1-3]

References

[1] J. M. Englert, J. Malig, V. A. Zamolo, A. Hirsch, N. Jux, Chem. Commun. 2013, 49, 4827 – 4829.

[2] D. Lungerich, J. F. Hitzenberger, M. Marcia, F. Hampel, T. Drewello, N. Jux, Angew. Chem. Int. Ed..
2014,
53, 12231-12235.

[3] D. Lungerich, J. F. Hitzenberger, W. Donaubauer, T. Drewello, N. Jux, Chem. Eur. J. 2016, 22, 16755-16759.

Figure 1
Mediating Charge Shift Reactions in Electron Transport Chains
Authors: Guldi Dirk M.
Published: February 2020

In Nature, energy and electron transfer processes in the photosynthetic machinery following light absorption have been perfectionated. To mimic the aforementioned, that is, efficiently utilizing light to separate charges and, in turn, to generate solar fuels, a great variety of multicomponent artificial photosynthetic systems have been designed and synthesized. Incentives for the design build around molecules have been taken from Nature: For example, implementing suitable electrochemical gradients across arrays of several molecular building blocks have enabled the unidirectional transformation of solar energy into electrical energy. A key parameter is the right balance between the reduction / oxidation strengths of the individual building blocks and their spatial arrangements. Both affect the thermodynamic driving forces for each step and, in turn, the overall efficiency. Notably, acceptor-donor1-donor2 or acceptor-donor1-donor2-donor3 types of artificial photosynthetic systems have been reported. Besides an initial charge transfer, charge shifts take place via oxidative electron transfers from donor1 to donor2 and, eventually, to donor3.

Considering the effectiveness of multicomponent systems, in which photoexcitation triggers a cascade of short range electron transfers, we report on two sets of novel multicomponent DA1A2s – Figure 2. These DA1A2 types feature electron transport chains with C60 and C70 of different electron acceptor strengths to create an electrochemical gradient. As a complement to electron accepting C60 / C70 either zinc porphyrins (ZnP) and zinc phthalocyanines (ZnPc) were employed. The motivation for our pump-probe investigations was to establish the role of ZnPc or ZnP as light harvester and electron donor to power unidirectional (reductive) charge shift reactions along a variety of electron transport chains.

In summary, we will demonstrate the control over unidirectional charge shift along electron transport chains en route towards highly energetic, long-lived charge separated states. Key is, however, a charge shift mediating state, whose relative energy determines the overall efficiency. If the energy of the mediating state, on one hand, is higher than the charge separated state, resonance conditions enable efficiencies as high as 50%. If the energy, on the other hand, is lower than the charge separated state, deactivation to the ground state limits the efficiency to 10%.
Chromophore Containing Photonic Assemblies Via Host-Guest Chemistry and DNA Self-Assembly
Authors: Jayawickramarajah Janarthanan , Pathak Pravin , Rahn Harrison P , Vik Ryan S
Published: February 2020

The tendency of organic chromophores, such as porphyrins and phthalocyanines, to aggregate via aromatic interactions in water is an important issue since such aggregation can lead to attenuation of the chromophore’s photophysical properties. This talk will illustrate how nanoarchitectures containing well-placed chromophores can be (a) self-assembled in highly competitive aqueous media whilst (b) the individual chromophores are precluded from aggregation via host-guest chemistry. The connecting thread of the talk will be on how hierarchical self-assembly using an array of supramolecular interactions (especially host-guest chemistry, and programmable DNA self-assembly) can be used to construct photoactive ensembles and nanostructures. The beginning section of the seminar will discuss the development of multi-chromophore containing wires, spheres, and thin films. The latter section of the seminar will discuss our recent efforts to prepare photonic systems via synthetically modified DNA oligonucleotides and enzyme co-factors (luciferin).
The Effect of Surface Pretreatment on the Corrosion Performance of Graphene Coatings on 6061 Aluminum Alloy
Authors: Huang Chien-Yu , Liu Xiao-Jie , Chen Chun-Hu , Lee Yueh-Lien
Published: February 2020

This study presents an investigation into the effect of surface pretreatment on the electrochemical characteristics and corrosion behavior on graphene coated 6061 aluminum alloy (Al 6061). The corrosion properties of graphene coated 6061 aluminum alloy with different surface pretreatments were studied using electrochemical impedance spectroscopy (EIS), polarization measurement, and salt spray testing (SST). Surface morphologies of pretreated and coated samples were analyzed by optical microscope (OM) and scanning electron microscopy (SEM), respectively. The integrity of graphene coating transferred from the growth Cu substrate onto the Al 6061 was examined by Raman spectroscopy. We also investigated the adhesion between the graphene and Al 6061 by measuring the water and diiodomethan contact angle, and calculating the surface free energy of various pretreated samples.
Some Extensions of the Galvele Approach to Localized Corrosion, Including the Effect of Cation Complexation
Authors: Nguyen Van Anh Thi , Ghaznavi Mahmoudreza , Carcea Anatolie G , Newman Roger C.
Published: February 2020

Analytical and numerical modeling have been used to extend the understanding of pitting corrosion in a one-dimensional geometry. The approach is based on that of Galvele [1] and later experimental studies that supported many of Galvele’s findings [2], but with more detail and new features. We have examined both ideal solutions, and non-ideal solutions where the diffusivity (D) is a function of concentration (c) for any species, as well as cation complexation by chloride.

The essential result that Galvele obtained was:

Epit = A – B log [NaCl],

where Epit is the pitting potential and B should be 0.059 V at 298 K.

Laycock and Newman [2] clarified that the quantity A contained the kinetics of the anodic dissolution reaction, and defined a quantity that they called the transition potential, ET, which is the potential where the anodic current density i becomes equal to the anodic limiting current density, iL.

The origin of Galvele’s equation is an analytical solution of the governing reaction-transport equation (Nernst-Planck equation) considering an unreacting ion such as Cl-. In this solution, as refined by Newman [3], the second term in Galvele’s equation is the IR drop in the pit at the limiting current density iL. Importantly, iL depends on [NaCl] because the contribution of migration to the outward flux of dissolved metal cations increases as [NaCl] decreases.

In the present work, we have examined the following refinements, with the following preliminary outcomes:

The variation of B with [NaCl] – B is constant at 0.059 V over a certain range of [NaCl], but decreases at high [NaCl]. This is easily understood physically. At low [NaCl] there appear to be small deviations from 0.059 V that are still under investigation.

The effect of introducing a D(c) – this turned out to be an intriguing area of study, and new results will be presented at the meeting. Briefly, the effect of varying diffusivity is not as great as might be assumed.

Cation complexation – this is the latest aspect to be investigated. Changes in B with complexation are expected. Such changes may explain the different empirical values of B found in different materials including stainless steels.

References:

Jose R. Galvele, Transport Processes and the Mechanism of Pitting of Metals. J. Electrochem. Soc., 1976, 123(4), 464-474.

N.J. Laycock, R.C. Newman, Localised Dissolution Kinetics, Salt Films and Pitting Potentials. Corrosion Science, 1997, 39(10-11), 1771-1790.

R.C. Newman, Pitting Corrosion of Metals, The Electrochemical Society Interface, 2010, 19(1), 33-38.
Capability Evaluation of Houttuynia Cordata Leaf Extract As Environmentally Eco-Friendly Inhibitor for Steel Corrosion in HCl 0.1 M
Authors: Pham Hien Van , Nguyen Vu Si Hoai , Mai Tri Dinh , Phan Binh Minh Quoc , Vu Thu Thi Hanh , Nguyen Nam Dang
Published: February 2020

In this study, the anti-corrosion capability of Houttuynia cordata leaf extract (HLE) in HCl 0.1 M on mild steel was investigated by electrochemical testing methods consisting of potentiodynamic polarization (PD), electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), and surface analysis including scanning electron microscope (SEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The results showed an increase in corrosion resistance of steel with increasing HLE concentration and suggested that its action as a mixed-type inhibitor, resulting in excellent inhibition efficient of HLE on steel surface and lower corrosion rate. Surface analysis exhibited profoundly influential impact of HSL components for improving steel surface protection by protective film formation via adsorption process of HLE components. The steel surface protection mechanism was also provided and discussed in detail.
Corrosion Performance of New Composite Coatings Onto Carbon Steel By Electrochemical Methods
Authors: Branzoi Florina , Branzoi Viorel , Pahom Zoia
Published: February 2020

In this study, cyclic voltammetry, galvanostatic and potentiostatic electrodeposition mode was used for the synthesis of new composite (Ppy-AOT/PNEA) coatings onto carbon steel of type OLC 45 for corrosion protection.

monolayer poly (N, ethylaniline) (PNEA), polypyrrole (Ppy), and bilayer PNDMA/ Ppy-AOT and Ppy-SDS/PNDMA coatings have been electropolymerization on carbon steel by cyclic voltammetry, galvanostatic and potentiostatic synthesis techniques from aqueous solutions 0.1 M N, ethylaniline, 0.1M pyrrole, 0.01 M dioctyl sulfosuccinate sodium (AOT) and 0.1 M, 0.3 M and 0.5M oxalic acid. In order to include dioctyl sulfosuccinateions as dopant in the polypyrrole, AOT was also added to the polymerization solution of polypyrrole. Characterization of monolayer and bilayer polymer coatings was carried out by cyclic voltammetry, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) techniques. Corrosion behaviour of PNEA-AOT/PPY coated carbon steel of type OLC 45 was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques in 1 M H2SO4 and 1M HCl solutions. The results of the corrosion tests showed that PNEA/PPY-AOT coatings ensure good corrosion protection of carbon steel OLC 45 in aggressive media. Bilayer coatings revealed better corrosion protection efficiencies than monolayer coatings. The new nanocomposite realized by this method is promising and might lead to industrial applications in the protection of the carbon steel substrates against corrosion

The corrosion protection efficiency follows the order: OLC 45/PNEA/PPY-AOT > OLC 45/PPY-AOT/PNEA > OLC 45/PPY- AOT > OLC 45/PNEA because the presence of these coatings causes a significant decrease in corrosion rate.

Keywords: nanocomposite films, electrochemical electrodeposition method, corrosion protection, SEM, EIS, FT-IR
Corrosion of Carbon Steel in CO2-Saturated Brines Investigated By Rotating Disk Electrode and Scanning Vibrating Electrode Technique
Authors: Feng Ruishu , Ziomek-Moroz Margaret , Tylczak Joseph H , Ohodnicki Paul R
Published: February 2020

CO2 corrosion has been extensively studied because dissolved CO2 makes carbon steels susceptible to corrosion and failure during oil and natural gas exploration, production, transmission, and processing as well as in CO2 sequestration and capture systems. A rotating disk electrode (RDE) system and the scanning vibrating electrode technique (SVET) were used to study CO2 corrosion, including localized corrosion that often occurs when dissolved CO2 is present, especially at higher pH. The carbon steel, which meets the American Petroleum Institute 5L grade X65 standard, was investigated in 3.5%wt NaCl solutions from pH 4 to 8 at 30 oC. The effects of CO2, pH, and mass transport were studied. In situ electrochemical measurements were carried out in the RDE system at different rotating rates to measure the corrosion rates and determine the corrosion mechanism, including linear polarization resistance, electrochemical impedance spectroscopy, electrochemical frequency modulation, cyclic voltammetry, and Tafel analysis. Surface analysis using scanning electron microscopy and X-ray photoelectron spectroscopy was performed on the corroded samples. SVET was used to characterize the localized corrosion on the steel surfaces at different conditions.
(Invited) Novel Dilute Nitride III/V-Semiconductor Laser System for the Monolithic Integration to Si-Micro- and Nanoelectronics
Authors: Ludewig Peter , Volk Michael , Volz Kerstin , Stolz Wolfgang
Published: February 2020

In recent years the class of dilute nitride III/V-semiconductors and corresponding heterostructures are gaining increasing interest both from fundamental as well as applied point of view. This is caused by their unique optoelectronic properties and in particular by the novel conduction band formation process leading to an extreme band gap bowing with increasing N-content in the crystal.

The novel material system Ga(NAsP) can be grown lattice-matched to (001) Si-substrate. The incorporation of N in the Ga(NAsP)-material allows for a significant reduction in the lattice constant, which leads on one side to a dislocation free deposition. On the other side the specific conduction band formation process in these materials is used to realize a direct band gap semiconductor. By applying a variety of physical investigation techniques the high crystalline quality as well as the direct band gap character of the novel Ga(NAsP)-material system have been verified. Ga(NAsP)/(BGa)(AsP)-MQWH were grown on exactly oriented (001) Si substrates embedded in thick (BGa)P separate confinement hetero-layers by metalorganic vapour phase epitaxy (MOVPE). The optoelectronic properties and first lasing characteristics of Ga(NAsP)-MQWH on (001) Si-substrate will be presented and possible integration concepts with Si-CMOS-based micro- and nanoelectronics will be discussed.
(Invited) Electronics in Flatland
Authors: Banerjee Sanjay K
Published: February 2020

2D materials such as graphene, transition metal dichalcogenides and topological insulators have opened up avenues in beyond-CMOS device concepts. We will discuss our work involving single or many-particle 2D-2D tunneling, leading to transistors with negative differential resistance. We also explore spintronics in these systems for novel logic and memory devices. We will also discuss the use of these materials in less esoteric, but more practical high frequency, mechanically flexible FETs for IoT applications.

The work was done in collaboration with H.Movva, A.Sanne, A.Rai, S.Kang, C.Corbet, R.Ghosh, A.Roy, B.Ghosh, S.Majumder, D.Akinwande, E.Tutuc and L.F.Register
Effect of Resistive Switching-Layer Oxygen-Concentration on Nonvolatile Memory Characteristics for Carbon-Oxide Based Reram
Authors: Jin Soo-Min , Kwon Ki-Hyun , Kim Dong Won , Kim Hye-Jee , Kim Do Jun , Park Jea-Gun
Published: February 2020

Resistive random access memories (ReRAM) are highly promising as one of next-generation memories due to high current density, high speed, simple structure, and low power consumption [1]. Recently, amorphous carbon oxide based ReRAM has been researched due to its strong advantages over typical ReRAM chacacteristics such as large memory margin (Ion/Ioff
> 100), high switching speed (20~50ns) and CMOS compatible process. In this work, we present the electrical features of amorphous carbon oxide, working as a resistive switching layer [2], where tunsten (W) / amorphous carbon oxide / platinum (Pt) configuration with the pattern size of ranging 34 to 1,921 nm. The thickness of carbon oxide, O2 flow rate of RF magnetron sputter, and N2-annealing temperature were varied with the device cell size to optimize the device performance. The device of amorphous carbon oxide based ReRAM demonstrated typical electrical characteristics, i.e., the set voltage of 1.8 V, the reset voltage of –2.0 V, high resistance state current of 4.6×10-11 A at 0.1 V, and low resistance state current of 7.5×10-9 A at 0.1 V. Moreover, stable endurance and retention were observed at 10 nm-thick amorphous carbon oxide after N2-annealing at 400 oC, which were the endurance of 1.0×106 cycles with a margin (Ion/Ioff
) of 3.5×101 and retention of 105 sec with a margin of 6.2×101. In particular, we present the mechanism and memory characteristics on operating behavior of the amorphous carbon-oxide based ReRAM via investigating the effect of amorphous carbon-oxide thickness, O2 flow rate of RF magnetron sputter, and N2-annealing temperature on the electrical characteristics by using auger electron spectroscopy(AES), energy-dispersive X-ray spectroscopy (EDS), cross sectional transmission electron microscopy (TEM) and X-ray diffraction (XRD).

* This material is based upon work supported by the Ministry of Trade, Industry & Energy(MOTIE, Korea) under Industrial Technology Innovation Program (10068055).

[1] Daniele Ielmini, Semicond. Sci. Technol. 31 (2016) 063002

[2] Claudia A. Santini et al, NAT COMMUN, 6:8600 (2015)

Figure 1
Improvements to the Charging Efficiency of an All-Iron Redox-Flow Cell
Authors: Jayathilake Buddhinie Srimali , Manohar Aswin , Plichta Edward J. , Hendrickson Mary A. , Narayanan S. R.
Published: February 2020

Development of reliable, low cost, durable and ecofriendly energy storage systems for large scale applications is essential to support the intermittent generation from renewable energy sources. Among the different electrochemical energy storage technologies, redox-flow batteries are promising for large-scale applications due to its design, scalability and low cost. [1] In the quest for an inexpensive as well as eco-friendly energy storage system, we have been investigating a novel anion-exchange-membrane-based iron chloride redox flow rechargeable battery with the aqueous electrolytes composed of solution of iron chloride, ammonium chloride, and specific electrolyte additives. [2] Such an all-iron redox-flow battery based on iron chloride with the Fe3+/Fe2+ redox couple at the positive electrode and the Fe2+/Fe0 redox couple at the negative electrode has a cell voltage of 1.21 V and a theoretical specific energy of 170 Wh/ kg.  Although we have shown the technical viability of the concept, the development of such a battery into a large-scale system has still remained a challenge due to the parasitic hydrogen evolution reaction at the negative electrode that lowers the efficiency of the charging process. Our efforts have aimed at increasing the efficiency of the charging process at higher charging current densities by minimizing the rate of the hydrogen evolution reaction.

This report, we present the effect of operating parameters on the rate of the parasitic hydrogen evolution reaction and the charging efficiency of the redox flow battery. By increasing the electrolyte pH to 3 in the presence of ascorbic as an electrolyte additive, we have achieved a charging efficiency of 94% at 80 mA cm-2 at the negative electrode (Fig.1a). Elevated plating bath temperature significantly increased the faradaic efficiency during both iron electrodeposition and electro-dissolution achieving 98% charging efficiency at 20 mA cm-2 at 333K at pH 3 (Fig.1b). We will also present results on the electrochemical kinetics for hydrogen evolution and iron deposition studied at iron-plated graphite electrode during charging process of the all iron redox flow cell.

Acknowledgment

Authors acknowledge US Army RDECOM CERDEC CP&I for financial support of this work.

References:

1. F. Pan and Q. Wang, Molecules, 20 19711 (2015).

2. A. K. Manohar, K. M. Kim, E. Plichta, M. Hendrickson, S. Rawlings and S. R. Narayanan, Journal of The Electrochemical Society, 163, A5118 (2016).

Figure 1
Long-Term Cycling of Quinone Flow Batteries Using a Crossover Balancing Strategy
Authors: Kwabi David , Goulet Marc-Antoni , Gerhardt Michael R. , Aziz Michael J.
Published: February 2020

Quinone-based redox flow batteries (RFBs) have comparable performance to all-vanadium RFBs but with reactants composed of earth-abundant elements, and hold promise for safe, cost-effective, large-scale energy storage. One of the major obstacles to their practical implementation is capacity fade during cycling, which is faster than that observed in all-vanadium systems (65-70% capacity retention after 10,000 cycles) [1]. Unlike in all-vanadium RFBs, the crossover of active species across the membrane leads to capacity loss that is not readily recovered with a simple rebalancing method. We present a study of a strategy for alleviating crossover-induced capacity loss, in which the flux of electroactive species across the membrane is balanced by an opposite flux of the same species in the complementary redox state. A model for balanced species flux across the membrane is developed and implemented in a quinone-based battery with a perfluorinated membrane. Its application results in a replenishment of capacity in the capacity-limiting side of the battery and reduces capacity loss to < 0.02%/cycle over hundreds of cycles at the time this abstract is being written. Criteria for extending this approach to other redox flow battery chemistries, and for enabling the use of inexpensive separators will be discussed.

[1] B. Dunn, H. Kamath, and J.-M. Tarascon, Science, 334 (2011).

Figure 1. Computed fluxes of bromine and bromide ions across a Nafion membrane as a function of state-of-charge (SOC). At 50% SOC, fluxes across the membrane are balanced.

Figure 1
Electrochemical Oxidation of Psychoactive Pharmaceutical Caffeine in Aqueous Medium Using RuO2/IrO2/TaO2 Coated Titanium Anode
Authors: Selvendiran Periyasamy , Muthukumar Muthuchamy
Published: February 2020

Caffeine is one of the most widely used psychoactive drug in the world .Apart from being commonly used in beverages (soft drinks, tea and coffee), it is one of the components of painkillers, medication against migraine, fatigue, drowsiness and breathing problems, etc. Unlike other psychoactive substances, utilization of caffeine is legal in most countries. It is generally recognized as safe at usual moderate doses, though it becomes toxic in excessive amounts. Several clinical studies showed a relation between caffeine and anxiogenic effect and/or panic disorders. Its consumption is also associated with an overall lower risk of malignant growth like hepatocellular, endometrial or colorectal cancer. Still the effect of caffeine and its environmental degradation products on aquatic living species is not known. Therefore, as a preventive measure a development of an effective removal method is needed. Electrochemical oxidation method has many advantages such as low cost, simplicity, and amenability to miniaturization. Selective electrochemical oxidation for the caffeine in aqueous medium using RuO2/IrO2/TaO2 coated titanium anode has been investigated. The effect of the process variables, such as initial pH, current density, processing time, concentration of the electrolyte and anode materials, on the degradation of caffeine was studied. During the various stages of electrolysis, parameters such as COD, TOC and UV-Vis spectra were examined and discussed. The maximum chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiency of 96.9% and 100% was achieved at pH 7, operated at the current density of 5.1 mA/cm2, electrolyte (Na2SO4) concentration of 0.1 M and at 240 min of electrolysis using RuO2/IrO2/TaO2 coated titanium anode. Electrochemical oxidation process could effectively reduce the COD and TOC from the Caffeine in aqueous medium. The degradation of the caffeine was confirmed using FT-IR, HPLC and GC-MS analysis. The degradation pathway proposed.
Kinetics of Zinc Ion Removal from Wastewater By Electrocoagulation
Authors: Chen Xiujuan , Ren Panpan , Li Tao , Liu Xingbo
Published: February 2020

In this work, the research focused on the removal of zinc ions from the synthetic wastewater by electrocoagulation (EC) with aluminum electrodes. The effects of current density, electrode spacing, initial concentration, wastewater pH and conductivity on the removal efficiency and energy consumption were systematically investigated. The results showed that the zinc removal efficiency increased with the increasing current density and residence time. With a relatively low energy consumption of 0.35 kWh/m3, all of zinc ions (50 mg/L) were removed from the synthetic wastewater within 20 minutes EC treatment, 8.3 mA/cm2 for current density, and 5.3 for pH. Later with an energy consumption of 0.88 kWh/m3, all of zinc ions (250 mg/L) were removed from the wastewater at EC time of 50 minutes. In addition, the kinetic study was applied to analyze the removal rate of zinc ions by EC at different current densities and initial concentrations. Different mechanisms of zinc removal were implied by comparing the results of the low initial concentration (≤ 250 mg/L) and the high one (≥ 500 mg/L). It was reasonable to conclude that, besides the co-precipitation effect of the aluminum hydroxide flocculation, the electrochemical reduction of zinc ions at the cathode also contributed to the zinc removal, especially at a high initial concentration.
Investigation of Solid Oxide Fuel Cell Anodes, Cathodes and Electrolytes with X-Ray Scattering and Spectroscopy
Authors: Braun Artur , Ilavsky Jan , Allen Andrew J. , Jemian Pete R.
Published: February 2020

Solid oxide fuel cells (SOFC) are solid state electrochemical devices which operate at high temperatures up to 1000°C. Their components, particularly cathode and anode are structurally and chemically very complex. Specifically the porosity and internal surface area is a functionality per se and needs to be optimized so as to warrant optimum electrochemical conversion of fuel to electricity with a long service live. The assessment of the pore space is therefore instrumental for the functionality assessment. In contrast, the solid electrolyte shall have little or no porosity so as to present a good barrier to parasitic gas diffusion from anode to cathode, and vice versa. Of importance is ultimately the size of the electrochemical active interface. Traditionally, optical and electron microscopy imaging methods have been employed for the assessment of the pore space of such electrode assemblies. More recently, focussed ion beam tomography methods have been applied with success.

We provide an alternative method which requires no image analysis methods and which has a very high spatial resolution and element specific sensitivity. The method of choice is small angle scattering, which we have employed on a set of industry grade SOFC assemblies which were taken from stacks that had been run with sulfur ruch and sulfur depleted fuel, compared against the pristine electrodes. We present a detailed qualitative and quantitative assessment which is based on the chemical contrast variation and enhancement by using synchrotron radiation with tunable X-ray energy (anomalous small angle X-ray scattering).

With the data which obtained we are able to sketch a sulfur poisoning degradation model for the electrochemical interface (triple phase boundary) of the SOFC.

[1] A. J. Allen, J. Ilavsky, P. R. Jemian, A. Braun, Evolution of electrochemical interfaces in solid oxide fuel cells (SOFC): a Ni and Zr resonant anomalous ultra-small-angle X-ray scattering study with elemental and spatial resolution across the cell assembly, RSC Adv., 2014, 4, 4676-4690.
Pulse Plating of Copper from Deep Eutectic Solvents
Authors: Green Todd , Su Xiaomeng , Roy Sudipta
Published: February 2020

In recent years there has been considerable interest in the deposition of metals, alloys and semiconductors from ionic liquids (ILs). These melts possess a number of advantages over traditional aqueous solutions, especially for the deposition of reactive metals and where the current efficiency of the process is inherently low. Deep eutectic solvents (DES) are a new class ionic liquids which possess low toxicity, low cost, and relatively good electrochemical characteristics. They have been used to deposit a wide range of materials and, unlike traditional ILs, it is often possible to obtain acceptable deposit characteristics in the presence of significant amounts of water contamination. This makes them particularly suitable for industrial-scale plating. Until now, most studies employing ILs or DES have concentrated on DC plating and there have been relatively few reports of electrodeposition under pulse conditions.

Ionic liquids have differing characteristics to aqueous solutions, particularly in terms of their double layer structure, mass transport properties, kinetics and conductivity. These differences indicate that pulse parameters developed for aqueous systems are unlikely to be optimal for deposition from ILs. For example, the very low diffusivity of the depositing species indicates that the DC and pulse limiting current are expected to be substantially lower compared to aqueous solutions. In this paper we will examine some of the constraints placed on the selection of pulse parameters dictated by the unusual properties of ionic liquids.

As an example of a ‘model’ system we will examine copper deposition from a deep eutectic solvent (DES) comprising ethylene glycol and choline chloride. After selection of appropriate pulse parameters some preliminary results obtained for copper electrodeposition will be reported. Of particular importance is the presence of a corrosion reaction in the off-time which puts additional constraints on the choice of pulse parameters.
(Electronics and Photonics Division Award Address) Compound Semiconductor Science and Technology: A Retrospective
Authors: Buckley D. Noel
Published: February 2020

The very first State-of-the Art Program on Compound Semiconductors (SOTAPOCS I) was called to order at the 166thMeeting of The Electrochemical Society in New Orleans in the Fall of 1984. The first lightwave transmission system was then less than 4 years old and the first commercial cell phone was less than 3 years old. In fact, CW operation of a semiconductor laser at room temperature had been achieved less than 15 years before and even the transistor was still relatively young at 37 years. Our world has changed dramatically in the intervening years and compound semiconductors have played a vital role in the technologies that brought about that change. This talk will look back on some of the highlights and milestones in the development of compound semiconductors, recall some of the events along the way, and reflect on the key role played by The Electrochemical Society.
(Invited) Latest Status of Semiconductor Electrodeposition
Authors: Lincot Daniel
Published: February 2020

The electrodeposition of semiconductors is a living field of electrodeposition technologies since many years, which remains highly challenging both at the fundamental level and at the application level. Well known examples are related to the electrodeposition of cadmium telluride thin films, or copper indium diselenide which went from fundamental studies to industrial applications in the field of photovoltaics. Semiconducting oxides like ZnO, copper oxides are other examples of successful developements. New routes are explored today for the electrodeposition of crystalline silicon thin films. Electrodeposition thus remains as a potential alternative or supplement to classical vapor phase or metallurgical routes for next generation technologies, as in photovoltaics, where low cost and large area processing capabilities are still required. In this presentation we will present the state of the art of the electrodeposition of semiconductors, both on the basis of a literature survey and also from direct studies carried out in our laboratory and research environment. We will focus on the design of electrodeposition conditions and concepts allowing, in the on going studies, to deposit either directly or indirectly semiconductor materials. Direct deposition allows the direct formation of the material while indirect formation involves the deposition of precursor materials (like metallic layers) followed by reactive post treatments. A special attention will be given to the deposition of semiconductors on semiconductors (including photodeposition) and to emerging field of the deposition on localised areas, like for microcells areas in new photovoltaics devices.
Solar-Driven Reduction of 1 atm CO2 to Formate at 10% Energy-Conversion Efficiency by Use of a TiO2-Protected III-V Tandem Photoanode in Conjunction with a Bipolar Membrane and a Pd/C Cathode Electrocatalyst
Authors: Zhou Xinghao , Liu Rui , Sun Ke , Chen Yikai , Verlage Erik , Francis Sonja A , Lewis Nathan S , Xiang Chengxiang("CX")
Published: February 2020

A solar-driven CO2 reduction (CO2R) device that consists of a tandem InGaP/GaAs/TiO2/Ni photoanode in 1.0 M KOH for oxygen evolution reaction (OER), a Pd/C nanoparticles dark cathode in bicarbonate electrolyte at pH=8.0 for CO2R reaction and a bipolar membrane exhibited a solar-to-fuel (STF) conversion efficiency of 10%. The Pd/C nanoparticles showed low overpotential (< 100 mV) and high faradic efficiency (> 94%) for CO2 reduction to formate at 8.5 mA cm-2. The bipolar membrane exhibited low formate crossover and high transference number for proton and hydroxide at the steady-state pH gradient. The effective coupling between two different electrolytes that optimize the performance of CO2R reaction and OER provides new cell design spaces for efficient solar-fuel generation.