A. Schechter

Hydrogen production on-demand by hydride salt and water two-phase generator

by ניר שוולב, Yakir Nagar, and A. Schechter

H 2 generators based on "powderto-water" have a high energy density. Rotating discs mechanism had... more

How to grow a movable mini-garden in a droplet: Growing chemical gardens in a water and aqueous ethanol solutions droplets deposited on a superhydrophobic surface

Colloids and Interface Science Communications, 2015

Abstract Growth of chemical droplets confined by a droplet placed on a superhydrophobic surface i... more Abstract Growth of chemical droplets confined by a droplet placed on a superhydrophobic surface is demonstrated. FeCl3 seed crystals were deposited on a polymer superhydrophobic surface. Droplets containing an aqueous solution of the potassium hexacyanoferrate (K4Fe(CN)6·3H2O) were allowed to contact the seed crystals. Typical small-scale chemical gardens, similar to those grown in open vessels, were observed within 20 μl droplets. Micrometrically scaled filaments were registered. The Laplace overpressure developed in the droplet was insufficient for suppressing the growth of chemical gardens. Addition of ethanol delayed the growth of chemical gardens.

Advanced Liquid Electrolyte Solutions

Lithium Batteries

ABSTRACT The major families of this class are ethers, esters, and alkyl carbonates, which are hig... more ABSTRACT The major families of this class are ethers, esters, and alkyl carbonates, which are highly important for the field of high energy density batteries. These solvents and their formulas are summarized in Figure 18.1. Other important solvents are acetonitrile (AN), dimethylsulfoxide (DMSO), N-N dimethyl formamide (DMF), methylene chloride and nitromethane. The latter five solvents are mainly important for electroanalytical use and organic synthesis. As discussed later in this chapter, the type of salt plays a major role in determining the electrochemical window of a polar aprotic system. Commonly used anions, in conjunction with Li+, are PF6 −, CIO4 − and BF4 −. All polar aprotic solutions may contain atmospheric contaminants such as O2, H20 and C02, which are reactive and may play an important role in determining the electrochemical behavior.

Free-Standing, Thermostable, Micrometer-Scale Honeycomb Polymer Films and their Properties

Macromolecular Materials and Engineering, 2008

Honeycomb structures were obtained using the same experimental technique explained in much detail... more

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Recent studies on the correlation between surface chemistry, morphology, three-dimensional structures and performance of Li and Li-C intercalation anodes in several important electrolyte systems

Journal of Power Sources, 1997

This paper reviews some advances in the comparative study of lithium and graphite electrodes in a... more This paper reviews some advances in the comparative study of lithium and graphite electrodes in a large matrix of solvents, salts and additives. The major purpose of this work was to support R&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;D of lithium metal and Li-ion batteries by understanding the correlation between the anode&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s performance, its morphology and three-dimensional structure upon cycling, interfacial electronic properties and the surface

Ethylmethylcarbonate, a Promising Solvent for Li‐Ion Rechargeable Batteries

Journal of The Electrochemical Society, 1996

Ethylmethylcarbonate, a Promising Solvent for Li‐Ion Rechargeable Batteries. [Journal of The Elec... more

Effect of external voltage on Pseudomonas putida F1 in a bio electrochemical cell using toluene as sole carbon and energy source

Microbiology, 2011

A bio electrochemical cell (BEC) was constructed as a typical two-chamber microbial fuel cell (MF... more A bio electrochemical cell (BEC) was constructed as a typical two-chamber microbial fuel cell (MFC), except that it was operated under external voltage instead of constant resistance as in an MFC. The anode chamber contained a pure culture of Pseudomonas putida F1 grown in a minimal medium containing toluene as the sole carbon and energy source. Operating the BEC under external voltages of 75, 125, 175, 250 and 500 mV (versus an Ag/AgCl reference electrode) led to increased bacterial cell growth to an OD 600 of 0.62-0.75, while the control BEC, which was not connected to external voltage, reached an OD 600 of only 0.3. Examination of the current generated under external voltages of 75, 125, 175, 250 and 500 mV showed that the maximal currents were 11, 23, 28, 54 and 94 mA m-2 , respectively. Cyclic voltammetry experiments demonstrated an anodic peak at 270 mV, which may imply oxidation of a vital molecule. The average residual toluene concentration after 147 h in the BEC operated under external voltage was 22 %, whereas in the control BEC it was 81 %. Proteome analysis of bacterial cells grown in the BEC (125 mV) revealed two groups of proteins, which are ascribed to charge transfer in the bacterial cells and from the cell to the electrode. In conclusion, operating the BEC at 75-500 mV enabled growth of a pure culture of P. putida F1 and toluene degradation even in an oxygenlimited environment.

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A comparison between the electrochemical behavior of reversible magnesium and lithium electrodes

Journal of Power Sources, 2001

This paper describes brie¯y the difference between reversible lithium and magnesium electrodes. I... more This paper describes brie¯y the difference between reversible lithium and magnesium electrodes. In the case of lithium, the active metal is always covered by surface ®lms. Li dissolution±deposition is reversible only when the surface ®lms contain elastomers and are¯exible. Hence, they can accommodate the morphological changes of the electrode during the electrochemical processes without breaking down. In an ideal situation, lithium is deposited beneath the surface ®lms, while being constantly protected in a way that prevents reactions between freshly deposited lithium and solution species. In contrast to lithium, magnesium electrodes are reversible only in solutions where surface ®lm free conditions exist. Mg does not react with ethers, and thus, in ethereal solutions of Grignard reagents (RMgX, where R alkyl, aryl, X halide) and complexes of the following type: MgAlX 4Àn R n H R H n HH 2 , R and R H alkyl groups, X halide, A Al, 0 < n < 4 and n H n HH n, magnesium electrodes behave reversibly. However, it should be noted that the above stoichiometry of the Mg salts does not re¯ect the true structure of the active ions in solutions. Mg deposition does not occur via electron transfer to simply solvated Mg 2 ions. The behavior of Mg electrodes in these solutions is discussed in light of studies by EQCM, EIS, FTIR, XPS, STM and standard electrochemical techniques. #

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The Study of Electrolyte Solutions Based on Ethylene and Diethyl Carbonates for Rechargeable Li Batteries

Journal of The Electrochemical Society, 1995

The behavior of Li electrodes was studied in ethylene and diethyl carbonates (EC‐DEC) solutions o... more

High resolution remote sensing of particles and aerosols in the W-band (92–100 GHz)

by Natan Kopeika and A. Schechter

2011 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems (COMCAS 2011), 2011

ABSTRACT The interaction between W-band radiation and particles and/or aerosols is very important... more ABSTRACT The interaction between W-band radiation and particles and/or aerosols is very important for imaging and remote sensing applications. The reflectance and back scattering of such media are important parameters in the design of active and passive W-band imaging and remote sensing. In order to investigate those parameters we designed and constructed a unique W-band spectroscopic system operating at 92–100 GHz. The system is based upon two parabolic mirrors, two diagonal mirrors, a high power high resolution continuous wave tunable W-band source, and a unique detector. The spectrometer is fully computerized. In order to investigate the interaction with particles we prepared unique samples. The samples were prepared from polyethylene powder mixed with known percentage of 44 μm stainless steel particles. The mixture was heated to about 2000C and 100 mm sample plate was extracted. Samples with different percentage of stainless steel particles were prepared as well as a reference pure polyethylene plate keeping the same volume for all samples. Reflection function measurements of those samples are presented in this work. Back scattering measurements will be carried out in the future.

Prototype systems for rechargeable magnesium batteries

Nature, Jan 12, 2000

The thermodynamic properties of magnesium make it a natural choice for use as an anode material i... more The thermodynamic properties of magnesium make it a natural choice for use as an anode material in rechargeable batteries, because it may provide a considerably higher energy density than the commonly used lead-acid and nickel-cadmium systems. Moreover, in contrast to lead and cadmium, magnesium is inexpensive, environmentally friendly and safe to handle. But the development of Mg batteries has been hindered by two problems. First, owing to the chemical activity of Mg, only solutions that neither donate nor accept protons are suitable as electrolytes; but most of these solutions allow the growth of passivating surface films, which inhibit any electrochemical reaction. Second, the choice of cathode materials has been limited by the difficulty of intercalating Mg ions in many hosts. Following previous studies of the electrochemistry of Mg electrodes in various non-aqueous solutions, and of a variety of intercalation electrodes, we have now developed rechargeable Mg battery systems tha...

A short review on the comparison between Li battery systems and rechargeable magnesium battery technology

Journal of Power Sources, 2001

An active metal that should be considered as an anode material in high energy density batteries i... more

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New insights into the interactions between electrode materials and electrolyte solutions for advanced nonaqueous batteries

Journal of Power Sources, 1999

... structure. This is illustrated in Fig. 2. Finally, the surface films formed on lithium and li... more

Methyl Propyl Carbonate: A Promising Single Solvent for Li-Ion Battery Electrolytes

Journal of The Electrochemical Society, 1997

Methyl propyl carbonate (MPC) solutions containing Li salts can be used as a single-solvent elect... more Methyl propyl carbonate (MPC) solutions containing Li salts can be used as a single-solvent electrolyte with addition of ethylene carbonate (EC). Graphite electrodes can be cycled at high reversible capacity in MPC solutions containing LiPFâ and LiAsFâ. The use of acyclic, unsymmetric alkyl carbonate solvents, such as ethyl methyl carbonate (EMC) and MPC in Li-ion based electrolytes, increases the stability of the graphite electrode. Whereas a small amount of EC is still needed as cosolvent in EMC solutions to obtain stable surface films on graphite electrodes, the authors show here that the surface films produced on graphite in MPC solutions (without added EC) are highly stable, allowing reversible Li-ion intercalation. To understand this trend, they investigated the surface chemistry developed on lithium and carbon electrodes in MPC solutions in conjugation with electrochemical studies.

The Reversible Giant Change in the Contact Angle on the Polysulfone and Polyethersulfone Films Exposed to UV Irradiation

by Edward Bormashenko, G. Whyman, and A. Schechter

Langmuir, 2009

Water contact angles on polysulfone and polyethersulfone films exposed to UV irradiation have bee... more Water contact angles on polysulfone and polyethersulfone films exposed to UV irradiation have been found to decrease dramatically. We relate this phenomenon to the formation and release of disulfonic acid from the irradiated films, a well-known surfactant. The phenomenon appears to be reversible, namely, cleansed surfaces retained their initial contact angle. The revealed phenomenon may provide a means of controlling the spreading of liquids on polysulfone and polyethersulfone films and seems promising for use in microfluidics applications.

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