bluuebunny/crossref_metadata_2025 huggingface dataset:
Fundamental Properties of Organic Redox Couples for Aqueous Flow Batteries
Authors: Hoober-Burkhardt Lena , Yang Bo , Prakash G. K. Surya , Narayanan S. R.
Published: February 2020

With penetration levels of renewable energy sources, such as wind and solar, nearing 33% in many places, large scale energy storage is desperately needed. Organic redox flow batteries (ORFB) are a promising solution, as they meet the demanding requirements for large-scale energy storage.1 They are environmentally friendly, easily scalable, highly efficient, and have low cost. Quinones are an excellent candidate for ORFB as they have a system cost of <$100/KWh and a charge capacity of 200-490 Ah/kg.

Organic molecules such as quinones are ideal for an aqueous redox flow battery system based not only on their fast kinetics, but also on their ability to be tuned for solubility and electrode potential. Addition of substituent groups affects not only solubility and electrode potential but also the kinetics and mechanism of the redox reactions. Electrochemical studies were undertaken to understand these effects. This understanding will be beneficial for the deployment of these organic reactions in an ORFB.

Electrochemical properties of various quinones in acidic media were studied in an electrochemical half-cell at a rotating disk electrode (Figure 1). Diffusion coefficients were found to be in the range of 10-6 – 10-7 cm2/sec, while rate constants were found to be in the range of 10-3-10-4 cm/sec (Figure 2,3). We have explored a range of quinones with different substituent groups to achieve the desired solubility and electrode potentials suitable for use in the full redox flow cell. We will present understanding of the relationship between the values of kinetic parameters and substituent group placement. Additionally, we have screened other water-soluble redox molecules such as quinoxalines and hydrazides. We will also present our current understanding of the electrochemistry of these compounds and their suitablity for redox flow batteries.

Acknowledgements

The work presented here was funded by ARPA-E and the Loker Hydrocarbon Institute of the University of Southern California.

Reference

1) Yang, B.; Hoober-Burkhardt, L.E. Prakash, G.K.; Narayanan, S.R. ECS Meeting, San Francisco, CA, USA, Oct 27-Nov 1, 2013
(Invited) Impurity Co-doping of Gallium Nitride Materials for Enhanced Light Emission
Authors: Zavada John M
Published: February 2020

Impurity doping of silicon and other semiconductor materials has been an active research area for more than 20 years. There have been two main thrusts of this work, erbium doping to provide infrared light emission in silicon for telecommunications, and doping with other rare earths for full color displays and solid state lighting. Major advances in both of these areas have been achieved through metal-organic chemical vapor deposition synthesis of rare earth doped GaN thin films [1, 2]. However, the low efficiency emission in prototype devices has prevented commercial applications. In this talk, recent results concerning light emission from erbium doped and from europium doped GaN films will be discussed. Experimental data showing enhanced light emission through co-doping of the GaN films will be presented. The role of strain fields and theoretical simulations of location of rare earth ions in the GaN lattice will be included. These results indicate that significant ligh emission can be achieved through co-doping of GaN films.

[1] C. Ugolini, N. Nepal, J. Y. Lin, H. X. Jiang, and J. M. Zavada, Appl. Phys. Lett. 89 151903 (2006).

[2] A. Nishikawa, N. Furukawa, T. Kawasaki, Y. Terai, and Y. Fujiwara, Appl. Phys. Lett. 97, 051113 (2010).

[3] P. Kaur, S. S. Sekhon, J.M. Zavada, and Vijay Kumar, Phys. Rev. B (2012).
Magnéli Phase Titanium Oxide: Electrochemical Routes and Characterisation
Authors: Dunne Peter , Mieszala Maxime , Le Nader Victor , Philippe Laetitia , Michler Johann
Published: February 2020

Wide bandgap semiconductors such as TiO2 are highly versatile and industrially attractive materials. It has excellent chemical and thermal stability useful in a wide range of applications such as biomedical implants [1], cosmetics [2], and MEMS [3]. It is optically transparent in the visible and near infrared, with a bandgap of ~3.3 eV at room temperature, is employed in anti-reflection coatings, dye sensitive solar cells, can become super-hydrophilic under UV exposure, and can act as a photocatalyst. It occurs primarily as rutile or anatase but other metastable polymorphs such as brookite or oxygen deficient Magnéli phases, TinO2n-1, are possible [4].

The oxide can be deposited in near-room temperature baths via electrochemically induced precipitation [5]. However, it is challenging to deposit crystalline TiO2, typically it is amorphous and post-annealing is required to attain a crystalline phase. Of particular interest are the family of sub-oxide Magnéli phases, characterised by high electrical conductivity, and chemical stability [6], which are already finding electrochemical applications in areas such as batteries, fuel cells, cathodic protection, synthesis and environmental treatment [6]. Here we demonstrate the electrochemical routes required to achieve highly crystalline TinO2n-1 from room temperature aqueous electrolytes.

References

[1] D. P. Macwan, P. N. Dave, and S. Chaturvedi, J. Mater. Sci. 46, 3669 (2011).

[2] L. Shi, J. Shan, Y. Ju, P. Aikens, and R. K. Prud’homme, Colloids Surfaces A Physicochem. Eng. Asp. 396, 122 (2012).

[3] J.-C. Orlianges, A. Crunteanu, A. Pothier, T. Merle-Mejean, P. Blondy, and C. Champeaux, Appl. Surf. Sci. 263, 111 (2012).

[4] J. L. Murray and H. A. Wriedt, J. Phase Equilibria 8, 148 (1987).

[5] P. Kern, P. Schwaller, and J. Michler, Thin Solid Films 494, 279 (2006).

[6] F. C. Walsh and R. G. A. Wills, Electrochim. Acta 55, 6342 (2010).

Figure 1 - SEM images of TiO2 deposit on FTO. Left: typical hexagonal morphology with an amorphous TiO2 underlayer. Right: detail of a flower-like feature.
Spinel Oxide Catalysts for Oxygen Reduction in Microbial Fuel Cells
Authors: Hanna Nick , Reilly Annie , Crawford Amanda , Windisch Charles F
Published: February 2020

Microbial fuel cells offer many advantages in the production of energy from renewal sources. Unfortunately, their commercial implementation has been hampered by some serious technical challenges. In particular, like most fuel cells that incorporate oxygen reduction, power output is limited by the large overpotential for this reaction. Incorporation of a Pt catalyst will enhance the reaction rate to acceptable levels but at an unacceptable cost and, while less expensive alternative catalysts have been considered, none have shown the catalytic activity of Pt. This poster reports results of our efforts to develop a catalyst based on a mixed-transition metal oxide with spinel composition, NixCo3-xO4 (where x is approximately 1), that was previously found to be promising for oxygen reduction under alkaline conditions but not, to the best of our knowledge, the pH-neutral environment of a microbial fuel cell. The oxide is also known to exhibit an electron conduction mechanism based on small polaron hopping as well as a tendency to surface “reorganize” in response to its chemical environment, both possible advantages to interfacial reactions involving dissolved oxygen. Cyclic voltammograms of electrodes impregnated with NixCo3-xO4 showed marked improvement in oxygen reduction rates in neutral-pH-buffered solutions over uncatalyzed electrodes. The poster also reports on recent results of using electrodes modified with NixCo3-xO4 in a bench-scale microbial fuel cell.
Fabrication of Double Layered TiO2 Photoelectrodes Using Electrostatic Inkjet Printing
Authors: Seki Akie , Shimoyama Yuki , Ogawa Masafumi , Umezu Shinjiro , Kunugi Yoshihito
Published: February 2020

Dye-sensitized solar cells (DSSCs) are one of the most attractive electrochemical devices capable of converting light energy into electrical energy because they can be fabricated at low cost in an eco-friendly manner. Photo-electrode film of TiO2 nanoparticles in DSSC plays a major role in the light absorption and charge carrier separation and collection process. Popular fabrication methods of the photo-electrode ﬁlm are screen-printing, spray-coating, spin-coating, and blade-coating. Inkjet printing of functional materials has been attracting significant attention in the light of recent attempts to manufacture various electronics such as light-emitting diodes, thin film transistors, solar cells, memory devices, sensors, biological devices, passive circuit elements, etc. However, it is well known that current inkjet printers such as thermal and piezoelectric printers cannot eject a droplet of high-viscous liquid. TiO2 paste consists of aqueous solution of TiO2 nano-particles, surfactant and polyethylene glycol, and is very high viscosity. Recently, we developed new inkjet technology, electrostatically-injected spray method. When the strong electric field was applied to a nozzle, small droplets were ejected by the electrostatic force. In this study, we apply this inkjet printing technique to develop double layered TiO2 photo-electrodes.

The TiO2 paste was printed by electric field-induced inkjet printing on fluorine-doped SnO2-coated (FTO) glass electrodes and sintered at 450 °C for 30 min. DSSCs were prepared by a conventional procedure. Photovoltaic properties of each solar cell were characterized using simulated AM 1.5 sunlight illumination with an output power of 100 mW/cm2.

We have successfully fabricated double layered TiO2 photo-anodes using an electrostatic inkjet printing technique. The structures and morphologies of the TiO2 film, which ultimately influence the cell performance, were controlled by changing the distance between the capillary nozzle and the FTO substrate (spraying distance). The TiO2 film formed by longer spraying distance yielded a large surface area and a highly porous structure.
Photocatalytic Activity of Pt3ti/WO3 Photocatalyst Under Visible-Light Irradiation
Authors: Hashimoto Masanari , Jeevagan Arockiam John , Tsuda Takashi , Saravanan Govindachetty , Gunji Takao , Kaneko Shingo , Miyauchi Masahiro , Matsumoto Futoshi
Published: February 2020

In the past decades, enormous attention has been focused on semiconductor photocatalysis for environmental remediation because it can utilize solar energy to decompose various organic compounds in air and aqueous systems. Titanium dioxide (TiO2) is most widely studied photocatalysts because of its low cost, high reactivity and stability. However, only 5 % of solar energy can be use by TiO2 on account of its wide band gap energy. On the other hand, tungsten trioxide (WO3) is a visible-light responsive photocatalyst with a narrow band gap energy and similar valence band potential like that of TiO2. Hence, a much effort has been made to prepare WO3based photocatalyst for decomposition of organic compounds. In the present study, we have prepared photocatalysts (Pt, Pt3Ti) by thoroughly mixed with WO3 powder and precursor in a mortar. We have already reported that Pt3Ti ordered intermetallic compound is a promising catalyst for electrochemical oxygen reduction and methanol, ethanol oxidations.1,2 WO3 loaded photocatalysts were characterized by pXRD, UV, TEM and XPS. Further, we examine organic compounds decomposition under visible light irradiation over cocatalysts loaded WO3. The details about the synthesis, characterization and photocatalytic activity of catalysts would be discussed in the presentation.

References

1. H. Abe, F. Matsumoto, L.R. Alden, S. C. Warren, H. D. Abruna, and F.J. DiSalvo, J. Am. Chem. Soc.,130, 5452 (2008).

2. G. Saravanan, H. Abe, Y. Xu, N. Sekido, H. Hirata, S. Matsumoto, H. Yoshikawa, and Y. Y.-Mitarai, Langmuir, 26, 11446 (2010).

3. G. Saravanan, T. Hara, H. Yoshikawa, Y. Yamashita, S. Ueda, K. Kobayashi, and H. Abe, Chem. Commun., 48, 7441 (2012).
Mathematical Model for the Cathode of Ethanol PEM Fuel Cell
Authors: MESA Jesus ANTONIO , Lizcano Valbuena William Hernando , Camargo Amado Ruben de Jesus
Published: February 2020

A new phenomenological mathematical model that describes the behavior of the cathode of a polymeric fuel cell was developed. It includes the modelling of liquid water and all cathode layers (gas collector, gas diffusion layer, microporous layer and catalyst layer); additionally, the catalyst layer is described as spherical agglomerates according to experimental evidence [1].

Since the performance of the fuel cell is highly dependent on the structure of the catalyst; [2] and cell flooding cause decrease in oxygen transport and loss of active catalyst surface [3] affecting fuel cell efficiency. The model considers these two important aspects in order to obtain a better description of the phenomena.

As a purely predictive model, it only requires the design specifications of the membrane electrolyte assembly (MEA). Once the data is provided (thickness of the catalyst layer, the catalyst load, the fraction by weight of platinum on carbon, the weight fraction of ionomer inside the catalyst layer and the ionomer density) all other model parameters are derived through the balance equations.

The model solution provides the current density, the cell potential, ethanol crossover rate and concentrations in the catalytic layer and in the membrane. It can be used to calculate and predict fuel cell behavior with high accuracy.

It takes into account liquid saturation in the pores and apply the spherical agglomeration method for describing the topology of the catalytic layer. The two-phase method is used for the macroscopic description of the system, resulting in a differential model, which is solved by the Runge-Kutta Fehlberg method with prediction and correction of error.

References

[1] G. Lin,W. He, T.V. Nguyen, Modeling liquid water effects in the gas diffusion and catalyst layers of the cathode of a PEM fuel cell, J. Electrochem. Soc. 151 (12) (2004) A1999–A2006.

[2] N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, Single domain PEMFC model based on agglomerate catalyst geometry, J. Power Sources 115 (2003) 81–89.

[3] U. Pasaogullari, C.-Y. Wang, Liquid water transport in gas diffusion layer of polymer electrolyte fuel cells, J. Electrochem. Soc. 151 (3) (2004) A399–A406.
Detection of TCE Using Electrochemical Testing: Analyzing the Purity of Water
Authors: Saraf Shashank , Sakthivel Tamil Selvan , Reid David , Hench Larry , Seal Sudipta
Published: February 2020

Trichloroethylene (TCE) can be considered as one of the most dangerous and toxic organic pollutants. It is present in the groundwater with concentration as high as few ppm, as reported by the Environmental Protection Agency in USA. [1,2] Zero-Valent Iron sorbents are effective at removing TCE from water, but are too expensive to use for large quantity. One promising area of fly ash (FA) is its use as a sorbent, particularly to remove pollutants from water and wastewater in industry. However, raw fly ash has a relatively low surface area and is hydrophilic, hence in its raw form it is not efficient absorbent and easily mixes with water.

In this study, we set out to modify the fly ash into a zeolitic fly ash (ZFA) with high surface area (404 m2.g-1) by alkali fusion followed by hydrothermal treatment. The resulting zeolite material is subjected to hydrophobic surface treatments to produce a material that adsorbs organic components like TCE, and repels water. The concentration of TCE was measured by using simple characterization techniques such as UV-Vis spectroscopy and chronoamperometry measurements. TCE exhibits absorption maxima at 260 nm which was used to calibrate the concentration. The chronoamperometry measurements were done using stainless steel as working electrode. The TCE sorption capacity of the zeolitic fly ash is improved by the chemical modification and it was about three times higher than the as-received fly ash as shown in figure 1.

References:

1. Y. Liu, S. A. Majetich, R. D. Tilton, D. S Sholl, and G. V. Lowry, Environmental Science & Technology, 39(5) 1338 (2005).

2. J. Farrell, M. Kason, N. Melitas, and T. Li, Environmental Science & Technology, 34(3), 514 (2000).
Development of Mixed-Conducting Membranes for Hydrogen Separation
Authors: Doyle Brian , Gong Mingyang
Published: February 2020

As the clean energy demands of the world continue to increase, so too will the use of hydrogen containing fuels. For harvesting “green” energy, hydrogen of sufficient purity will need to be extracted either from hydrogen-rich fuel sources or post-processing flue gases, requiring efficient separation of hydrogen from the many byproducts that arise from hydrogen production. This pure hydrogen can then be utilized for various power generation processes. While there are many different materials to be chosen as membrane constituents for this separation, proton-conducting ceramics represent a particularly appealing option for purification of hydrogen as a fuel source of solid oxide fuel cells. In these applications, the relatively high operating temperature of the fuel cell allows the integration of ceramic membranes with promising proton conductivity that is higher than or comparable to other hydrogen separation material systems. Additionally, these proton conductors need to attain high permeation rates with low fabrication costs[1]. Recently, a ceramic electrolyte composed of BaZr0.1Ce0.7Y0.1Yb0.1O3-d (BZCYYb) has demonstrated high proton conductivity that has spurred research interest on its application in ceramic electrolyte and hydrogen membrane fields. [2]. In this work, we examine two main features of membrane performance, optimal hydrogen flux of the membrane and improved microstructure through scalable manufacturing techniques.

The membrane consists of a Ni-BZCYYb dense layer supported by a porous Ni-BZCYYb. The first part of the work identifies the optimal hydrogen flux through variation of the nickel content in an asymmetric dense Ni-BZCYYb pellet. The determination of the transference number for the ceramic phase allows us to optimize the electrical conductivity brought on by the nickel. The hydrogen flux through the Ni-BZCYYb was determined as a function of membrane thickness and hydrogen partial pressure. The hydrogen flux was determined by using a mass spectrometer, which correlates the measured hydrogen partial pressure to amount of hydrogen present in a known sweeping gas atmosphere. Results have shown a hydrogen flux of 0.714 ml/cm2min under 100% hydrogen at 750˚C.

The microstructure also plays an important role in the performance of an asymmetric permeation membrane. For dense ceramic membranes, the ohmic permeation resistance from the proton conduction is inversely proportional to the thickness of the membrane. By using a tape-cast method, the thickness of the dense layer can be tailored down to about 10 microns. The results demonstrate an optimized membrane in terms of nickel content and thickness of asymmetric dense/porous layers. This demonstrates the ability to fabricate a cermet hydrogen permeation membrane using a large-scale, industry method.

Further, various catalysts that may enhance hydrogen adsorption, dissociation, and oxidation on the surface of the hydrogen separation membranes are also explored and will discussed in the presentation.
Atomically Precise Au25 Nanoclusters for Efficient Electrochemical CO2 Conversion
Authors: Kauffman Douglas R. , Alfonso Dominic , Matranga Christopher , Siva Rajan , Qian Huifeng , Jin Rongchao
Published: February 2020

Two problems facing traditional electrocatalysts are large overpotentials and poor product selectivity. Atomically precise, ligand-stabilized Au25 nanoclusters are exciting catalyst candidates for reactions like CO2 reduction because they have an inherent negative charge, their crystallographic surface structure is precisely known, and they bridge the size-gap between molecules and nanoparticles. Remarkably, the Au25 nanocatalysts promoted the reduction of CO2 into CO within 100 mV of the electrochemical formal potential (thermodynamic limit). This represents an approximate 200-300 mV improvement over larger Au nanoparticles and bulk Au. Peak CO2 conversion occurred at -1 V vs. the reversible hydrogen electrode with ~100% efficiency and rates 7-700 times higher than larger Au catalysts and 5-100 times higher than current state-of-the-art processes. Optical spectroscopy, non-aqueous electrochemistry and density functional theory studied the Au25-CO2 interaction. Our data suggests CO2 adsorption facilitated through and electrostatic interaction with Au25, while the highly efficient conversion of CO2 into CO was promoted by the clusters negative charge. Ongoing efforts include electrode optimization, and long term stability testing of the Au25
- nanocatalysts. The Au25
- clusters show reaction turnover frequencies of approximately 70-100 molecules/Au25/s and stable operation in excess of 24 hours at -1 V. This work was published in the Journal of the American Chemical Society
2012, 134, 10237-10243; electronic DOI: 10.1021/ja303259q.
Self-Propelled Magnetoelastic Biosentinels for the Detection of Pathogenic Bacteria in a Stagnant Liquid
Authors: Horikawa Shin , Chai Yating , Zhao Ruiting , Wikle Howard Clyde , Chin Bryan A.
Published: February 2020

This paper investigates the use of self-propelled magnetoelastic (ME) biosentinels to seek out and capture pathogenic bacteria in a stagnant liquid. These ME biosentinels are composed of an asymmetric-shaped ME resonator coated with a filamentous landscape phage that specifically binds with a pathogen of interest. When a time-varying magnetic pulse is applied, the ME biosentinels can be placed into mechanical resonance by magnetostriction. The resultant asymmetric vibration then generates a net force on the surroundings and hence generates autonomous motion in the liquid. As soon as the biosentinels find and bind with the target pathogen through the phage-based biomolecular recognition, a change in the biosentinel’s resonant frequency occurs, and thereby the presence of the target pathogen can be detected. In order to actuate the ME biosentinels into mechanical resonance of a desired mode, modal analysis using the three-dimensional finite element method was first performed, and the resonant frequency was determined. In addition, the net force due to the asymmetric vibration was calculated, and the resultant motion of the biosentinels was simulated. Both dynamic simulation and experimental results showed that the ME biosentinels can move autonomously through the liquid and actively bind with the target pathogen.
Selective Detection of Asbestos in Indoor Air
Authors: Ahn Hosang , Jung Byungkwon , Jang Dae Gyu , Park Hyejin , Joo Jin Chul , Kim Dong-Joo
Published: February 2020

Chrysotile, most part of widely used asbestos in building materials, is a serious cocern in indoor air can cause lung related cancers in a long period of time.

Even its harmfulness is well known, there is still no simple detection technology or monitoring system until now.

We performed several experiments to test the feasiblity of optic based detection of asbestos in a short time and at economic cost.

Asbestos samples were prepared by pretreating asbetos containing gloves and chrysotile from natural soils. Pretreated samples were characterized by PCM (Phase Contrast Microscopy) and PLM (Polarized Light Microscopy) methods as done before as general.

It was found that each sample contained approximately 15 % of chrysotile for sample from natural soil and 80 % of chrysotile for sample from asbestos glove, respectively.

Refractive index liquids (refractive indices= 1.55) were utilized to dye selectively chrysotile. Colorimeter and hyperspectral imaging sensor were tested to characterize chrysotile samples in varying concentrations according to dyeing w/wo refractive index liquids.

From the analysis, there was a preferred chrominance value and color in wavelength to detect chrysotile selectively and its preference was enhanced by dyeing with refractive index liquids.

We suggest that optic based asbetos detection can be one of promising technology in developing the real time asbestos monitoring system in the future.
Surface Engineered Pyrolyzed Carbon Electrode Arrays for Bio-Sensing
Authors: Song Yin , Wang Chunlei
Published: February 2020

There is urgent need to develop highly selective, sensitive and reproducible miniaturized bio-sensing platform based on reliable interface that is compatible with microfabrication processing. Our research objective is to advance fundamental research by fabricating pyrolyzed carbon arrays with high surface area as a bio-sensing electrode, developing the functionalization methods to increasing biomolecules immobilization efficiency and further understanding electrochemical phenomena occurring at bio/carbon interfaces. The carbon microelectrode arrays with high aspect ratio and porous surface have been fabricated by carbon microelectromechanical systems (C-MEMS) while the nanomaterials such as graphene have been integrated to further increase surface area. To achieve the efficient covalent immobilization of biomolecules, various oxidation and reduction functionalization methods have been investigated. The oxidation treatment we used in this study includes vacuum ultraviolet, electrochemical activation, UV/Ozone and oxygen RIE. The reduction treatment includes direct amination and diazonium grafting. The functionalized surface has been characterized using XPS, CV and FTIR to confirm and calculate the surface coverage of different functional groups. The developed bio-sensing platform was then applied for several applications, such as: DNA sensor; Glucose sensor; H2O2 sensor; Aptamer sensor and HIV sensor. The performance and sensitivity of each biosensor will be discussed in the talk.
Cyclic Voltammetric Sensing of Ethanol Oxidation Using Palladium Nanoparticles with Organic Thiol-Ligand
Authors: Feliciano Ileana , Arroyo Lisandra , Cunci Lisandro , Diaz Diana Coral , Cabrera Carlos R
Published: February 2020

The detection of ethanol concentration is very important for different applications such as food industry, medicine, beverage, traffic safety and other health related analysis in blood, urine, and saliva. Recently, Pd nanoparticles (PdNP) have been of interest because exhibit interesting properties such as electrocatalytic activity towards alcohols oxidation in alkaline media, more abundant, and lower costs compared to Pt. In this work, we synthesized palladium nanoparticles with an organic-thiol ligand by chemical reduction method using sodium borohydride as reducing agent. The organic thiol ligands avoid the agglomeration and controlled particle sizes. The electrochemical detection of ethanol in KOH solution with PdNP with the organic thiol ligand on glassy carbon electrodes was done by cyclic voltammetry (CV). The morphology of PdNP nanoparticles with the organic thiol group was studied using SEM, XPS and TEM. The TEM do not demonstrated agglomeration of the nanoparticles and showed a particles size distribution of 2-10 nanometers. XPS spectra confirmed the presence of metallic palladium and sulphur peaks in the nanoparticles. The electrochemical results proved that the palladium nanoparticles with organic-thiol ligand had an excellent electrocatalytic activity for ethanol oxidation in alkaline media. The palladium nanoparticles are a promising material for ethanol sensors.
Surface Modified Biodegradable Polymeric Coated Magnesium Alloys for Controlled Degradation
Authors: Amruthaluri Sushma , Munroe Norman
Published: February 2020

Magnesium (Mg) alloys due to their biodegradable and biocompatible properties, have become potential candidates for orthopedic and cardiovascular implants. However, such applications have been fraught with unpredictable degradation rates, which have instigated attempts to control corrosion by alloying, surface coating and electrochemical treatment. The present research explores the influence of acid etching and electrochemical surface modification on polymer adhesion and corrosion rate of biodegradable polymer coated Mg alloys in simulated body fluids (SBF). The effect of immersion time on the degradation rate was analyzed by weight gain/loss measurements. Electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were used to assess the integrity and surface morphology respectively of surface modified and polymer coated alloys.
Investigation of the Corrosion Inhibition Efficiency on X65 Steel of Surfactant Mixtures of Alkyl Benzyl Dimethyl Ammonium Chlorides
Authors: Zhu Yakun , Free Michael L
Published: February 2020

The corrosion inhibition on X65 steel of a series of alkyl benzyl dimethyl ammonium (CnBDMAC) chloride surfactants was studied. The effects of surfactant concentration, hydrocarbon chain length, temperature, and salinity on the surfactant properties and inhibition efficiency were evaluated theoretically and experimentally. The distribution of surfactants among oil, aqueous phase, and steel surface was studied. The partitioning properties between oil and aqueous phase of the single surfactant/mixtures were evaluated using mass spectrometer. The surface tension was measured to determine critical micelle concentrations (CMC) and adsorption isotherms at the air-water surface. The inhibition efficiency was studied by linear polarization, electrochemical impedance spectroscopy (EIS), and Tafel slope method. Results are presented to show the inhibition effect dependence on the above mentioned factors. Mechanism behind the corrosion inhibition was discussed.
Study on the Interface Instability of Copper-Nickel Multi-Layer with Nano-Thickenss Formed By Pulse Reverse Plating
Authors: Kim Man , Lee Joo Yul , Choi Yong , Shin Eun Joo , Seong Baik Seok , Han Young Soo
Published: February 2020

Thin copper-nickel multi-layers with nano-thickness were prepared by pulse electro-plating. Transmission electron microscopy (TEM) revealed that the average thickness of the copper and nickel layers were about 14 and 16 nm. Annealing of the multi-layers at the temperature range of 300 and 600oC resulted in producing interface grooving. Small angle neutron scattering (SANS) well proved non-destructively that the interface grooving completely occurred above 500oC. The interface energy of the copper-nickel layer with nano-thickness will be determined by atomic force microscopy.
Porous Silicon-Carbon Composite Li-ion Anode Materials toward Practical Applications
Authors: Wang Donghai
Published: February 2020

Emerging application of Li-ion batteries for electric vehicles requires LIBs with higher energy density. Developing new anode materials with high specific capacity is an effective way to increase the energy density of LIBs. Due to its high theoretical capacity (3579 mAh/g) and abundance, silicon has been regarded as one of most promising alternatives to the currently-used graphite anode. However, there is a major barrier to the practical application Si: its large volume change during charge/discharge causes to severe pulverization of Si particles and degradation of Si electrodes, leading to poor cycling stability. Extensive efforts have been devoted to improving the cyclability of Si-based anodes with encouraging results, including development of various Si nanostructures/nanocomposites, novel binders and electrolyte additives.

In this talk, I will present development of micro-sized porous Si-C composite composed of interconnected Si nanoscale building blocks and carbon conductive network. The effect of Si nanoscale building blocks (size and doping composition) and carbon coating are studied on the electrochemical performance. We also engineered to produce graphene enabled dual conductive network on the micro-sized porous Si-C composite for high areal capacity electrodes toward practical application. New interpenetrated polymer gel binder for the Si anode materials will be also studied for improving efficiency and cycling stability of Si anodes. High temperature electrochemical performance of the Si anode material and related safety issues will be also discussed and correlated with the surface properties of Si materials.
Recent Advances in Electrode Design for an All-Iron Redox Flow Battery
Authors: Hawthorne Krista L. , Petek Tyler J. , Hoyt Nathaniel C. , Wainright Jesse S. , Savinell Robert F.
Published: February 2020

The energy production market must increase and decrease its output to match real time demand. This makes the process very inefficient and restricts the grid’s ability to rely upon intermittent renewable sources. Grid scale energy storage, such as a Redox Flow Battery (RFB) can alleviate these issues by storing energy when it is available and distributing energy as needed. One promising RFB chemistry is the all-Iron flow battery. Iron is low cost, domestically available, and the electrolytes can be used at mildly acidic pHs. The all-iron flow battery involves the iron (II/III) redox couple on the positive electrode and iron plating/stripping on the negative electrode. In conventional stationary electrodes (i.e. felts) the iron plates inside the active cell, meaning storage capacity is dictated by the plating density. Negative electrode design is therefore important for maximizing energy storage. Two approaches are investigated in maximizing plating density. The first approach utilizes the traditional hybrid flow battery configuration and focuses on manipulating the current distribution within the porous electrode to effectively utilize the active area. An optimal electrode design will provide a balance between minimizing polarization losses and maximizing the storage capacity. The second approach involves a nontraditional electrode design for the negative electrode: using a slurry electrode in order to decouple the power and energy capabilities of the all-iron battery. Slurry electrodes are made by mixing electrically conductive particles (on which the iron can plate) in the electrolyte containing the dissolved iron species. The slurry electrode is then pumped through the electrochemical cell. The design of this type of electrode requires fundamental information on the slurry’s electrical, electrochemical, and rheological properties, along with effective pumping and flow distribution strategies.
Mesoscale Models for Mechanics of Active Materials in Li-Ion Batteries
Authors: Simunovic Srdjan , Stershic Andrew , Kalnaus Sergiy , Allu Srikanth , Pannala Sreekanth , Turner John A
Published: February 2020

Most deformation models for Li-ion batteries are based on device-level empirical fits to the integral battery responses under the external and internal loadings. One of the main obstacles to establishing physics-based mechanical models formulations for Li-ion batteries is a lack of insight into the underlying kinematic micro-mechanisms of deformation of active materials. The active materials are compressed between current collectors, separators and other thermal management or structural layers that exert constraints and interlaminar forces that further complicate the material characterization.

We are using recently measured [1] microstructures of different lithium nickel manganese cobalt oxide (NMC) cathode configurations. The microstructures were determined by X-ray tomography under various pressure conditions. The experimental data on microstructure for increasing pressure is particularly convenient for identification kinematic mechanisms of deformation and formulation of interaction models between particles in electrodes. We use these reconstructed microstructures to generate computational models and to correlate the models to the experiments. Discrete element particle-based methods are used for modeling of mechanics of electrode materials at mesoscale where the meso-scale effects dominate the through-thickness response. Individual particle response can be decoupled from the assembly response and analyzed individually for possible non-linear deformation, fracture, crushing or crumbling. In this work we concentrate on the particle models that use particle size, shape, spatial distributions and inter-particle bonding. Various computational models for the microstructure are used in this study.

An example of a reconstructed battery electrode microstructure with weight ratio of 90:5:5 (active material : C : binder) and the mechanical compression simulation for the equivalent spherical particle model is shown in the figure below . The effects of postulated deformation mechanisms and their parameters are compared with the measures of microstructure configuration at increasing pressures. The developed models are used for modeling the mechanics of active materials in a computational framework for physics-based models of batteries [2].

References:

[1] Ebner M, Geldmacher F, Marone F, Stampanoni M, Wood V. X-Ray Tomography of Porous, Transition Metal Oxide Based Lithium Ion Battery Electrodes. Advanced Energy Materials. 2013;3:845-50.

[2] Allu, S., Kalnaus, S., Elwasif, W., Simunovic, S., Turner, J.A., Pannala, S., “A new open computational framework for highly-resolved coupled three-dimensional multiphysics simulations of Li-ion cells”, J. Power Sources 246 (2014), 876-886.
Investigation of the Effect of the Flow Rate Control on Capacity Decay in Vanadium Redox Flow Battery
Authors: Ko Dong Seok , Kim Jung Yun , Jung Taik Min , Kong Ji Hyun , Choi Eun Jung
Published: February 2020

Redox Flow Batteries(RFBs) have been considered as a promising energy storage technology that would be easy to be expanded into large-scale applications such as load leveling, peak shaving, uninterruptable power supplies, emergency backup and renewable integration and so on. RFBs could be classified into Fe-Cr, Zn-Br and V-V RFBs depending on their redox-couple. Among them, Critical attention has been directed to VRFB due to the fact that it produces less mix-up between both sides of electrolytes during cycles.

In VRFB, differential transfer rate of vanadium ions across the membrane can lead to capacity decay attributing to an increase of vanadium ions in one half-cell compared with the other. The capacity loss can significantly be restored in the physical way which is the remixing of two electrolytes, using a chemical technique, or an electrochemical method.

In this study, the correlation between the flow rate control of each half-cell side electrolyte and the capacity decay of VRFB is investigated to improve a cycle-life. Under the same flow rate condition, the two half-cell electrolytes respectively have different pressures due to their viscosity. The pressures could be adjusted by controlling the flow rate. Hence, the level control of both electrolytes could be maintained equally through the above methods. The level control can reduce the amount of vanadium ions that transfer to the other side across the membrane compared with the previous way and it can both improve a cycle-life of VRFB and minimize the additional energy for rebalancing.
Characterizing Discharge in Non-Aqueous Magnesium-Oxygen Batteries
Authors: Vardar Gulin , Sleightholme Alice , Siegel Donald , Monroe Charles W
Published: February 2020

Metal-O2 batteries are considered as an improvement upon current battery technologies due to their high theoretical energy densities. In particular, Mg-O2 batteries have one of the highest predicted theoretical specific energy densities [1]. Mg-O2 batteries have been previously demonstrated using aqueous electrolytes. However, aqueous chemistries are generally non-rechargeable. and more recent studies have targeted secondary systems based on non-aqueous Mg-conducting electrolytes in the context of Mg-ion and Mg-sulfur batteries [2]. Although Shiga et. al. reported the first rechargeable Mg-O2 battery using a non-aqueous electrolyte [3], the nature of the discharge product remains poorly understood. Our goal is to understand the discharge characteristics of Mg-O2 batteries using non-aqueous electrolytes.

Here we discuss our progress in characterizing the discharge products in Mg-O2 batteries. Figure 1 shows a discharge curve for such a battery using 0.05M Mg(BH4)2 in dimethoxyethane as the electrolyte. This electrolyte has been shown to reversibly deposit and dissolve Mg [4]. A voltage plateau of 1.1 V is observed, similar to previously reported non-aqueous Mg-O2 battery [3]. The measured cell voltage is low compared to the theoretical voltage expected from formation of MgO and MgO2 (2.95V and 2.91V vs. Mg/Mg2+, respectively) [5]. The carbon cathodes were characterized by x-ray diffraction and Raman spectroscopy. It was observed that MgCO3 was the dominant Mg compound. MgCO3 formation is likely due to reactions with the carbon cathode or with the electrolyte.

[1] Zu, C.-X., & Li, H. "Thermodynamic analysis on energy densities of batteries". Energy & Environmental Science, 4 (2011) 2614.

[2] Muldoon, J., Bucur, C. B., Oliver, A. G., Sugimoto, T., Matsui, M., Kim, H. S., et al. "Electrolyte roadblocks to a magnesium rechargeable battery". Energy & Environmental Science, 5 (2012) 5941.

[3] T. Shiga, Y. Hase, Y. Kato, M. Inoue, K. Takechi, " A rechargeable non-aqueous Mg-O2 battery". Chemistry Communications, 49 (2013) 9152.

[4] R. Mohtadi, M. Matsui, T.S. Arthur, S.-J. Hwang, “Magnesium borohydride: from hydrogen storage to magnesium battery.” Angewandte Chemie International Edition in English 51 (2012) 9780.

[5] Vannerberg, N. “Peroxides, Superoxides, and Ozonides of the Metals of Group Ia, IIa, and IIb”, Progress in Inorganic Chemistry, 4th ed.
In-Situ TEM Observation of Li-Air Battery Charge/Discharge Reaction
Authors: Kushima Akihiro , Kuriyama Nariaki , Kusumi Nobuhiro , Fujiwara Yoshiya , Koido Tetsuya , Li Ju
Published: February 2020

We conducted in-situ transmission electron microscopy (TEM) experiments to observe Li-air battery charge/discharge process to understand the reaction mechanism. A liquid confining cell was developed to prevent the electrolyte from evaporating in the high vacuum environment inside TEM. The cell has a silicon nitride membrane with gold electrode patterned on it. The electron beam transparency of the membrane enabled us to view the reaction in nano-scale resolution using TEM. The growth of the lithium oxide particles was observed during discharge. When the bias potential was applied to charge the cell, the particles formed during discharge were swept away in to the electrolyte. This implies that the decomposition of the lithium oxide particles took place at the interface between the particles and the electrode weakening the bond between them, and as a result the particles were detached from the electrode. Once the bias was set to discharge, new particles started to form again on the electrode. These processes of particle growth and detachment repeated in the charge/discharge cycles. A cyclic voltammetry data showed obvious peak for the discharge, but no peak was seen for the charging indicating the reaction was irreversible. This matches the observation of the detaching particles during charge. When the Li2O2 particles detach from the electrode, they lose electrical connection and cannot be decomposed. Therefore, Li is constantly consumed when the battery is cycled leading to the capacity loss. Our observation implies the detachment of discharge products from the electrode during charging may be responsible for poor cyclability of Li-air battery. The result also agrees with the improved cyclability of Li-air battery using porous electrodes which can confine the discharge product in the pore preventing it from flowing into the electrolyte.

Figure caption: TEM images showing a temporal evolution of discharge products during charge. Li2O2 particles formed on the gold electrode during discharge detached from the electrode and flowed away into the electrolyte during charge. The particles (i)-(iii) are marked with arrowheads to track the flow directions.
Development of CD Based Micro-Fluidics Device for High Throughput Particle Capture and Sampling
Authors: Hesketh Peter , Owen Drew , Ballard Matt , Mills Zachary , Alexeev Alexander , Hanasage Srinivas
Published: February 2020

A key challenge in biosensing is the capture of a target from a complex matrix. We are investigating methods to improve sampling and pre-concentration through efficient bead-based manipulation using magnetic fields. We present work on development of centrifugal micro-fluidic system for high throughput capture of fluorescent microparticles. The setup employs a disc consisting of an array of circular NiFe magnetic features that are axially symmetric. Sample is driven along numerous axially symmetric micro-channels in a radially outward direction. This pumping occurs under the influence of the centrifugal force created by the rotating disc. Super-paramagnetic beads are first introduced into the rotating device and are manipulated by a uniform external magnetic field. This enables the bead rotation around the magnetic features, thereby enhancing the mixing in the device. This setup is novel in that, it enables continuous high volume sampling and does not require external pumps/valves for fluid handling. The rotating disc enables both the pumping of fluid and bead rotation.
Sensor for Quantitative Analytical Determination of Sulphite in Wine Using a System of Modified Electrode and a Membrane Absorption System
Authors: Arce Roxana , Aguirre María Jesús , Romero Julio
Published: February 2020

The sulfite is commonly used antiseptic wine and food. You can find free or bound to phenols , aldehydes and other organic compounds. Its concentration at high levels produces toxic effects, such as pain when breathing in asthmatic patients , hypotension and gastrointestinal problems. Therefore it is useful to determine the electrochemically concentration , and with this, to separate , by absorbing membrane system , the other impurities present in food. Sulfite (SO3
-2) in aqueous solution is in equilibrium with bisulfite ( HSO3 - ) and sulfur dioxide ( SO2) , where their concentrations depend mainly on the pH. As to the electrochemical method , the cyclic voltammetry was used. This technique is widely used and is of considerable use in the study of oxide / reduction , detection of reaction intermediates and observing reactions monitoring electrode products formed in reactions . In conjunction with the cyclic voltammetry method of calibration curve is applied and thus determine how feasible it is to implement in an electrochemical analysis. The method of calibration curve represents the response of an analytical method to known concentrations of analyte . Previous studies done in the laboratory show that it is possible to find a potential range where the SO3
-2 shows an increasing response in current and potential displacement , and in addition, all the parameters are optimized for system performance membrane absorber .
Electrochemical Determination of Serotonin, in the Presence of Dopamine at a Carbon Paste Electrode Modified with Aunps-Bcd
Authors: Gil-Orozco Yazmín , Corona-Avendaño Silvia , Montes de Oca Maria Guadalupe , Ramirez-Silva Maria Teresa , Romero-Romo Mario A. , Palomar Manuel
Published: February 2020

In this work, we shown the electrochemical detection of serotonin (SR) in the presence of dopamine (DA), using a carbon paste electrode (CPE) modified with gold nanoparticles (NPs). The gold NPs were synthesized by the chemical method with b - cyclodextrin (AuNPs-b CD). Electrochemical treatment was applied to the electrode surface to distinguish between the oxidation signals of SR and DA. Electrochemical changes of the CPE surface were performed by forming multiple layers of AuNPs-b CD by cyclic voltammetry. The separation of oxidation peaks associated with the signals of SR and DA in acidic medium is shown in Figure 1. The results demonstrate that the film formation on the electrode inhibits the electrode surface passivation via the adsorbed species, which arise during the SR oxidation process. The electroanalytical determination was carried out using the electrochemical techniques: cyclic voltammetry (CV), differential pulse voltammetry (VDP) and square wave voltammetry (SWC).