bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of H-Bonding on the Electrochemistry of a p-Phenylenediamine-Based Urea. Competition Between Another Urea and a Cyclic Diamide Guest
Authors: Pham An T. , Clare Laurie A. , Woods Jessica E. , Smith Diane K.
Published: February 2020

In previous work done by our group, we reported the observation of strong oxidation-based redox dependent hydrogen bonding between an electroactive urea 1-phenyl-3-(p-N,N-dimethylaminophenyl)urea U(H)H and a cyclic diamide 1,4-dimethylpiperizine-2,3-dione (PZD) in methylene chloride.1Large negative shifts in the apparent, reversible one electron oxidation of U(H)H are observed upon addition of PZD, consistent with strong H-bonding of PZD to the radical cation of U(H)H.

However, with further study of U(H)H and similar molecules, it is clear that the electrochemistry and the mechanism is not as straightforward as once believed. Instead of undergoing a simple one electron oxidation, a variety of data now suggests that U(H)H actually undergoes a two electron oxidation to the quinoidal form with transfer of a proton to another U(H)H, which deactivates the second U(H)H. Thus the overall process corresponds to one electron per urea. Because acetonitrile is more polar than methylene chloride, it can better solvate the quinoidal urea and the protonated, unoxidized urea to prevent them from hydrogen bonding to each other. In contrast, stronger H-bonding between the quinoidal urea and the protonated, unoxidized urea is expected in the less polar solvent, methylene chloride and we believe this is what facilitates the observed reversible electrochemistry.

In the current study we are re-investigating the addition of PZD to U(H)H in light of our better understanding of the electrochemistry of U(H)H by itself. According to our new NMR titration data, PZD is H-bonded to U(H)H even without oxidation, which is consistent with our previous study. The binding constants, K, measured in different electrolyte solutions between PZD and U(H)H show that there is an electrolyte effect. In the NMR titration experiment without electrolyte, due to the solvent effect, PZD is more strongly H-bonded to U(H)H in the less polar solvent CH2Cl2 than in CH3CN (K in CH2Cl2 = 60.4 M−
1and K in CH3CN = 17.8 M−
1). With a large anion electrolyte, NBu4B(C6F5)4 in CH2Cl2 , the binding constant is greater (K = 95.9 M−
1) than with a small anion electrolyte, NBu4PF6 in CH2Cl2 (K = 48.6 M−
1). This is consistent with the larger potential shift observed with the addition of PZD in NBu4B(C6F5)4 in CH2Cl2 solution relative to NBu4PF6 in CH2Cl2. This suggests that the smaller PF6−ion may be competing with PZD for the binding site.

Re-examination of the cyclic voltammetry of U(H)H suggests the same overall reaction, 2e− oxidation of half the urea with proton transfer to the other half, is occurring with or without PZD present. However, the peak potentials are affected by the presence of PZD indicating the overall reaction is facilitated by PZD.

1. Jessica E. Woods, Yu Ge, and Diane K. Smith, Journal of the American Chemical Society
2008
130 (31), 10070-10071.
Formation and Mathematical Modeling of Electrical Field Distribution within TiO2 Nanotube Arrays
Authors: Zhao Ying , Hoivik Nils , Wang Kaiying
Published: February 2020

Self-ordered TiO2 nanotubes fabricated by electrochemical anodization have received considerable attention due to its unique nanostructure as well as potential applications. The nanotubes can be implemented on solar cells and gas sensors owing to its photoelectrical properties, and on water splitting/ hydrogen production and CO2 conversion from photocatalytic point of view.

However, the formation mechanism of the hexagonal nanotubes is still being developed and none has been worked out a really quantitative form that would correctly yield numerical figures. According to a number of previous theoretical models, the formation of the pores is resulted from the competition of the oxidation (TiO2 membrane growth process: TiO2+6F-+4H+→TiF6
2-+2H2O) and dissolution (hollow nanotube formation process: Ti+2H2O/2OH-→TiO2+4H+/2H++4e). In order to get better understanding on these two simultaneous processes, the evolution of electrical field distributes on the working electrode are crucial factors for nanotube initialization and formation.

In this paper, self-ordered TiO2 nanotube arrays were fabricated by electrochemical anodization. A high-purity titanium foil (Purity of 99.7%, size of 20 mm × 10 mm × 0.5 mm) were used as anode after surface degreasing by acetone and ultra-sonication, and surface washing and drying with de-ionized water and nitrogen. The experimental set-up is shown in fig 1a. The anodic oxidation process was conducted at 50V for 4 hours in electrolytes with composition of NH4F (0.5 wt%)/ glycol/ H2O (3.0 vol%). A platinum wire (Purity 99.9%, diameter ~ 0.25mm and length ~ 20 mm) was used as cathode in this process. A representative SEM (Scanning Electron Microscope) image of TiO2 nanotube structure is shown Fig.1b. We further implemented this experimental data into COMSOL simulation to verify the effects of nano-sized structures on electrical field distribution. The mathematical simulations were carried out with identical spacious geometry at micro and nano size level respectively. Fig. 2a shows the mathematical modeling of electrical distribution on assumed microtubes with diameter of 3 µm, length of 4 µm and gaps between tubes of 2 µm; Fig. 2b displays the simulated electrical distribution, which are fitted into the experimental data: 100nm in diameters (approximately) and 1µm in length, 50nm in gaps. Comparing the two mathematical simulations, it is concluded that the size of the structure plays a significant role on both the amplitude and the direction of the surface electrical field distribution.

In summary, formations of TiO2 nanottubes have been studied by electrochemical anodization. Mathematical simulations have been performed at micro and nano scale for simulating possible electrical distribution on the TiO2 tubes. The parameters of boundary condition are closely related to electrical distribution and can be distorted due to the dimensional effect between two neighboring structures.
Society Award Lecture - Vittorio de Nora Award Address: On-Wire Lithography: An Electrochemical Approach to Controlling Nanoscale Architecture
Authors: Mirkin Chad
Published: February 2020

On-wire lithography (OWL) is a template-based, electrochemical process for forming one-dimensional solution dispersible arrays of nanorods with programmably synthesized nano- and micro-scale gaps. OWL provides excellent control over the nanowire diameter (from 30 to 360 nm depending on the membrane pore size), segment length (from 6 nm to a few microns), gap size (from 1 nm to a few microns), composition (e.g., Au, Ni, Ag, Pt, Pd, PEDOT, PTh, P3HT, PPY, PPV) of the different nanowire components. The versatility of this novel technique has allowed for the fabrication of a wide variety of structures with emergent and highly functional properties that are advancing studies of SERS, plasmonics, and plexcitonics and forming the basis for novel molecular electronic, optoelectronic, encoding, and chemical and biological detection devices.
Optical Biosensor for Detection of Listeria monocytogenes
Authors: Sarkar Dibyo , Mitra Sushanta
Published: February 2020

In this work we have designed and optimized a Mach-Zehnder Interferometer (MZI) optical biosensor for detection of food borne pathogen, Listeria monocytogenes. Different MZI configurations are simulated and the best one in terms of minimal losses is identified for further fabrication of the sensor. The fabricated MZI sensor has selectivity towards Listeria and the limit of detection for the device is 10^5 cfu/ml. The sensor also provides a way to detect unknown concentration of Listeria through power measurements.
Combined Dot Sensors in the Domain of Food, Pharmaceutical and Biological Areas
Authors: VAN Staden Jacobus Frederick , Stefan-van Staden Raluca Ioana
Published: February 2020

Combined dot sensors are new tools in sensors' technology. Different scenarios regarding the innovation, development, design, behaviour, implementation and application of dot sensors will be outlined. They were designed for food, pharmaceutical or biological analysis. Food additives such as colorants and ascorbic acid were determined directly from food and beverages, sildenafil citrate in pharmaceutical formulations and dopamine from pharmaceutical and biological samples. The working dot sensors were based on diamond or carbon paste modified with different porphyrin base or metal-porphyrin complexes. Different electrochemical techniques such as, differential pulse voltammetry (DPV) were used for the assay of the samples. The lower limits of detection obtained allowed the assay of these analytes at levels that do not need preconcentration of the samples.

Acknowledgements

The present work was supported by the Romanian National Programme

PN II, Ideas, Contract Nr. 100/27.10.2011.
Enantioanalysis of S-Ketoprofen Using Potentiometric and SPR Sensors
Authors: Stefan-van Staden Raluca Ioana , VAN Staden Jacobus Frederick , Bokretsion Rahel Girmai , Aboul-Enein Hassan Y.
Published: February 2020

Ten enantioselective, potentiometric and SPR sensors based on carbon paste and gold impregnated with alpha-, betta-, carboxymethyl-betta-(as sodium salt), 2-hydroxyl-3-trimethylammoniopropyl -betta-(as chloride salt) and gamma-cyclodextrins, were proposed as a chiral selectors for assay of S-ketoprofen raw materials and in its pharmaceutical formulation Ketoflam capsule. The best response was obtained when betta-cyclodextrin was used for the electrode design. The sensors showed very low detection limits (of 10-8 to 10-9 magnitude orders). Stability constants values were also recorded for the interaction between S-ketoprofen and chiral selectors using SPR method.

Acknowledgements This work was supported by UEFISCDI PNII Program Ideas 2011-2014, Contract nr. 123/05.10.2011 and by ERC-like-3/07.2012 program.
Synthesis and H2 Gas-Sensing Property of ZnO Nanobelts
Authors: Jiang Wufeng , Hao Suju , Zhang Yuzhu , Ling Yunhan
Published: February 2020

ZnO nanostructures have been found to be of wide and diverse applications, such as field effect transistors, dye-sensitized solar cell, photoelectric devices and gas sensors, etc. ZnO nanostructures with different dimension various morphologies, including to nanowires, nanorods, nanotubes, nanoflowers and nanobelts have successfully synthesized by means of different methods. Comparing with other nanostructures, ZnO nanobelts have specific properties. A simple and effective method for the preparation of ZnO nanobelts was introduced in this paper. By using the electrochemical oxidation and heat treatment method,a layer of ZnO nanobelts thin film was obtained on the surface of Sn. In the first, the Sn-Zn alloy films were anodized in 0.01 M·L-1 of oxalic acid solution, and then the prepared films were annealed at 500°C for 2h in air ambient. The samples were characterized by field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray diffraction (XRD). The results show that the ZnO nanobelts have a thickness of 20 nm, with widths of 200 nm and lengths of 1~5 μm. The H2 gas sensing property of the ZnO nanobelts was measured in a static apparatus at room temperature. It was found that the ZnO nanobelts exhibited excellent H2 compounds sensing property.
A Carbon Paste Composite Electrode with Mixture of Zirconium Dioxide and Titanium Dioxide to Detect Heavy Metals Studied By SEM and XPS
Authors: Lunsford Suzanne Kay , Nguyen Phuong Khanh Quoc
Published: February 2020

Our research group has developed a novel carbon paste composite electrode, in which titanium dioxide/zirconium dioxide was incorporated into graphite carbon paste, to detect cadmium and lead in aqueous solution by utilizing electrochemistry. In the current work, the newly developed titanium dioxide/zirconium dioxide carbon paste composite electrode was used to quantify lead and cadmium, individually and simultaneously, utilizing square wave anodic stripping voltammetry. Detection limits in the low ppb were achieved and the mechanism and the morphology of the electrode sensor designed were studied. The sensor was also tested in river water and well water samples to illustrate its potential for real world application will be illustrated. Scanning electron microscopy and X-ray Photoelectron Spectroscopy (XPS) were employed to investigate and characterize the electrode surface morphology and the mechanism will be discussed.
Low Power Consumption CO2 Gas Sensor Using Ionic Liquid
Authors: Honda Masahito , Itoh Toshihiro , Maeda Ryutaro
Published: February 2020

Recently, various gas sensors are investigated. Specially, CO2 gas sensor is worthy of the notice, because monitoring of CO2 gas concentration is important for energy-saving. For example CO2 gas concentration is required for 1000 ppm or less in space, such as office buildings, a building management method, a production plant, and an IT-related server room. An exhaust gas periodically compulsory in order to make the present condition and CO2 gas concentration below into a steady value. By minimizing the displacement volume of the air which is carrying out air-conditioning management using CO2 sensor, an air-conditioning system carries out efficient operation, and it aims at development of CO2 sensor corresponding to the low consumption power high integration interlocked with a sensor network system efficiently. However the conventional CO2 gas sensors have the following problems, 1) large power consumption, 2) large size and 3) long detection time. These problems are mainly caused by usage of a light source and heater. We are interested in the ionic liquids because the ionic liquids are 1) the conductivity is high at room temperature, 2) thermal and chemical property is high stable, 3) volatility is high and 4) adsorb polarity molecule gases as like CO2, NH3, SO2, and NO2. Therefore we develop CO2 sensor which converted CO2 concentration into ionic liquid which adsorbed CO2 specifically by impedance. Our sensor feature is that it isn't used light source and heater, it is used ionic response. It compares with conventional CO2 sensor, 1) low consumption power, 2) miniaturization, 3) high-speed response and 4) low consumption CO2 gas sensor using ionic liquids. We use ionic liquids of imidazolium salts, EMIMBF4, EMIMTFSI and DEMEBF4. The impedance of ionic liquids decreases along with increase of CO2 gas concentration. By measuring the impedance of ionic liquids, we can estimate CO2 gas concentration of the atmosphere. From the experiment, measurement resolution of CO2 gas concentration was 100 ppm. The power consumption of our proposed CO2 gas sensor is several tens of microwatts, and this value is 1/1000 smaller compared with conventional CO2 gas sensors (NDIR and Solid state electrolyte cell).
Simulation and Experimental Investigation of a SAW Sensor Containing a Microcavity Array in the Delay Path
Authors: Sankaranarayanan Subramanian , Bhethanabotla Venkat , Richardson Mandek
Published: February 2020

Summary

An integrated experimental and theoretical study was carried out to modify the delay path of a SAW device to include an array of cavities having square cross-sectional areas (microcavities). Our results show significant reduction in insertion loss and improved sensitivity to viscous loading. Trends dependent on the device geometry were elucidated through finite element modeling. It is found that devices having microcavities optimized for a particular substrate and wave mode improve sensor characteristics. Using results from the simulations as a basis, we fabricated devices on ST-X Quartz that support shear-horizontally polarized waves. A standard SAW delay-line and a SAW device containing microcavities were compared by measuring insertion loss and determining the sensitivity to changing glycerol concentrations. Our experimental results agree well with simulations and introduce delay path modification in the form of microcavities as an effective way to improve SAW sensing performance.

Motivation

Surface Acoustic Wave (SAW) devices can be used as direct, label free biosensors that monitor the interaction between a receptor and its target in real time through changes in the properties of the traveling wave (i.e., frequency, phase, and amplitude)1 . An ideal biosensor will be selective to the species of interest, robust, have high sensitivity and consume a small amount of power. It is common when dealing with SAW sensors to have high insertion losses. Several approaches have been utilized which includes the incorporation of reflective gratings, grooves and corrugated surfaces, and the application of a waveguide material to remedy this problem. Decreasing the amount of power consumed will limit the amount of heat generated that can adversely affect protein activity and increasing sensitivity will allow the detection of antigens at clinically relevant concentrations.

Results

In this study, we compare finite-element simulations and experiments on SAW devices whose delay path has been modified to include an array of microcavities. Two different substrates commonly used in biosensors were studied, ST-Quartz and 36° YX -LiTaO3. From simulations, we find that microcavities optimized for a particular substrate and wave mode scatter the incident wave causing constructive interference while acting as a waveguide limiting its penetration into the bulk. This results in a decrease in insertion loss as well as a shift in the center frequency, attenuation of higher frequency modes, and increased out of band rejection. The insertion loss of fabricated devices was measured using an Agilent 8753 ES network analyzer. A decrease in insertion loss and a positive shift in center frequency shown experimentally are in agreement with simulated results.
Nanotechnology Based Cell-All Phone-Sensors for Extended Network Chemical Sensing
Authors: Li Jing
Published: February 2020

Today’s chemical sensing networks work effectively to cover limited and specific physical area and environments with significant cost and overhead. In order to greatly expand coverage and realize greater WMD protection for the nation, a revolutionary breakthrough that provides for a much larger and lower cost sensing distributed network is required. In order to practice this idea, US department of homeland security, HSARPA program made a call for Cell-All Ubiquitous Biological and Chemical Sensing.

NASA Ames Research Center responded to the call and won the proposal award. The work presented here is a first ever complete intelligent network chemical sensing system with 1) a compact, low-cost, low-power, high-speed nanosensor array-based detector integrated with 2) a smartphone for detection of chemical threats and transmit the sensor data via cellphone communication system to 3) a network cloud for centralizing the chemical sensing information from multiple phone-sensors from various locations.

At NASAARC, we have developed miniaturized sensing modules that can connect with an iPhone for chemical detection using carbon nanotubes (CNT) based nanostructure materials. Our devices possess high sensitivity (ppmv - ppbv), fast response (in sec), high selectivity, low power (5mW without sampling fan and 27mW with sampling fan), and very small size like a postage stamp, and they have been demonstrated for integration with an iPhone for chemical sensing of ppm concentration level of carbon monoxide, and ammonia in Windex and chlorine gas in Bleach.

The prototype-sensing module can be easily connected with an iPhone. Software has been developed to control the sensor chip for chemical detection; to collect and process sensor data, to display the chemical identification and associated concentration, and the sensor response in real time on the iPhone screen, and to transmit sensor data via 3G and/or Wi-Fi to a central location – an Internet server, to build a wider range of sensing network.

An effective cell phone-based chemical detection network will take advantage of both the standalone computing capability of modern cellular phones and the ability to aggregate sensor data over the cellular network for distributed processing or to a centralized processing location. This chemical detection network expands the coverage and realizes greater protection for the nation from hazardous chemical attack.

Note: This work is funded by DHS HSARPA Cell_All Program.
Challenges and Practical Aspects of Working with Customers on System Design and Implementation
Authors: Deininger Debra
Published: February 2020

Synkera Technologies Inc. has developed a range of chemical sensors, and worked with customers in a variety of applications, including process control, air quality, industrial health and safety, and consumer markets to use these sensors in their systems. This talk will discuss these experiences and some lessons learned about the challenges of integrating sensors successfully into a wide range of devices. Ultimately, the total system can have substantial effects on sensor performance and the success or failure of a given sensor technology in the market.Synkera Technologies Inc. has developed several types of chemical sensors that are able to detect components of air quality, toxic gases and flammable gases. In the commercial implementation of these sensors, Synkera has worked with customers in a variety of markets, including process control, air quality, consumer and industrial health and safety applications, in order to successfully deploy these sensors in their systems. Here, we discuss these experiences and some lessons learned about the challenges of integrating sensors successfully into a wide range of devices. In particular, we discuss the effects of electronic design, user interface, mechanical and packaging design, and calibration and compensation algorithms on sensor performance.

Ultimately, the total system design can have substantial effects on sensor performance and the success or failure of a given sensor technology in the market.
Effect of Steel Surface Variation on Electrochemical Heterogeneity and the Protection Afforded By Organic Coatings
Authors: Jamali Sina Seyed , Mills Douglas John
Published: February 2020

A well-prepared surface is the foundation on which an effective protective paint system is built. Most adhesion theories consider a rough surface to be favourable for achieving a high adhesive strength with a given organic coating. However, results of some case studies have found no relationship1,2 or inverse relationship3,4 between corrosion protection properties of the organic coating and the surface roughness. In the present work four conventional surface preparation methods including ultra high pressure (UHP) hydroblasting, wet abrasive blasting, acid pickling and abrasion with emery were used and compared to an as received control surface. Scanning vibrating electrode technique (SVET) was used to study the formation of active anodic sites on a local scale. Multiple repetitive scans were performed to study the dynamic of anodic activity. Figure 1 shows the variation of anodic activity by type of surface preparation in the early stages of corrosion. The level of surface activity was compared with the surface roughness and surface free energy. Electrochemical Impedance spectroscopy (EIS) and Open Circuit Potential (OCP) methods were used to study the effect of surface preparation on electrochemical properties at the surface as well as at the interface.

Results revealed the important role of the native oxide film and the deleterious effect of surface contaminants on the protective performance of the subsequently applied organic coating. Also it was shown that a large surface profile combined with a highly active surface can be deleterious if an appropriate interaction between organic coating and metal is not achieved. This is due in part to surfaces with coarse surface profile presenting a larger active area. It appears that the number of initial anodic sites plays a key role in the long term anodic/cathodic activity and this number varies by the surface preparation method.

Figure 1 Local distribution of current density for (a) as received (control), (b) abraded, (c) acid treated, (d) hydroblasted and (e) abrasive blasted samples after 5 min immersion in 1 mM NaCl.

1. P.R. Sere, A.R. Armas, C.I. Elsners, A.R. Di Sarli, Corros. Sci.,
38, 853–866 (1996).

2. A. Momber, S. Koller, H. Dittmers, J. Protect. Coat. Lin., 44–50 (2004).

3. D.M. Santágata, P.R. Seré, C.I. Elsner, A.R. Di Sarli, Prog. Org. Coat.,
33, 44–54 (1998).

4. D.J. Mills, K. Schaefer, Prog. Org. Coat.
69, 193–198 (2010).
Corrosion Inhibition of C-Steel Using Supported and Non-Supported Cu-Nanoparticles/Benzotriazole
Authors: Abdullah Aboubakr Moustafa , Atta Nada Farouk , Galal Ahmed , Afifi Asmaa Ahmed
Published: February 2020

Depositing Cu nanoparticles on the C-steel surface using the self-replacement technique has shown a corrosion inhibition efficiency higher than 91% in acidic medium if the Fe/Cu system was preimmersed in 1 mM benzotriazole for 30 minutes. The use of polyaniline nanotubes as a support for the Cu nanoparticles did not enhance the inhibition efficiency of Cu nanopraticles for Fe. On the contrary, it decreased a little bit. This work compares between corrosion inhibition efficiency of the polyaniline nanotubes and Cu nanoparticles separately and in presence and absence of benzotriazole. In addition, this work introduces a new and simple technique that is able to decide how the benzotriazole molecules interact with the Cu surface. It was proven using this technique that at the free corrosion potential, the interaction takes place mainly through the adsorption mechanism rather than the Cu(I)BTA film formation one.

The image shows the change of the corrosion type from the uniform to the pitting form.
Effect of Ca and Y on the Oxidation of Mg Alloys
Authors: Lee Dongbok , Yadav Poonam , Abro Muhammad Ali , KIM Minjung
Published: February 2020

The AZ91D magnesium alloys containing 1% Ca and 1% Y were cast and oxidized between 350 and 500oC in atmospheric air to study the effect of Ca and Y on the oxidation of Mg alloys. The Mg+1% Ca alloy consisted of α-Mg, Al12Mg17, and Al2Ca. The AZ91D+1% Y alloy consisted of α-Mg, Al12Mg17, and Al2Y. Al2Ca and Al2Y were present in the form of platelets or blocky particles along the boundaries of primary α–Mg grains.

The oxidation rates observed for the three alloys in the study decreased in the following order: AZ91D, AZ91D+1% Y, and AZ91D+1% Ca. As the oxidation progressed, the compact MgO oxide scale became porous, non-adherent, thick, and fragile. Ca, in the AZ91D+1% Ca alloy, was the most active element, and it appeared to diffuse outward toward the oxide layer rather easily. The presence of CaO in the oxide layer retarded the oxidation of the Mg alloy. Both the oxide scale and the matrix of the AZ91D+1% Y alloy contained oxygen. The dissolution of oxygen beyond the oxide scale indicates that Y could not effectively deter the ingress of oxygen, although the 1% Y content did increase the oxidation resistance of the alloy.

Acknowledgement. This work is the outcome of "Environment-friendly and Energy-efficient Manufacturing Technology of Eco-Mg" program (No. 10035292-2010-01) funded by the Korea government Ministry of Trade, Industry and Energy.
Understanding the Phenomenon of Biocorrosion on Uncoated and Coated AA-2024
Authors: Paez Maritza Angelica , Vejar Nelson , Azocar M. Ignacio , Gulppi Miguel , Melo Francisco , Zagal Jose H
Published: February 2020

Microorganisms have a strong tendency to colonize solid surfaces, leading to a complex microbial community that strongly adheres to the substrate, called biofilm. Biofilms are detrimental to the underlying substrates, causing physical degradation or biodeterioration of the metal surfaces. This phenomenon is widely recognized as biocorrosion or microbiologically influenced corrosion. Among the many microorganisms which induce the degradation or corrosion of metallic materials, Pseudomonas is one of the most studied and it is associated with corrosion of aluminum and its alloys.

In this work microbiologically influenced corrosion of an aluminium alloy, AA-2024, in the presence of Pseudomonas aeruginosa was studied.

In order to understand the mechanism by which the bacterium promotes corrosion in AA-2024, bacteria were cultured for different times in the presence of AA-2024 alloy samples. The morphology of the metallic surfaces was studied by optical microscopy and the bacterial population, living or dead, was examined in a confocal microscope. Localized corrosion was followed by further observations of metallic sections after immersing in the bacterial culture for defined time intervals. Susceptibility to corrosion was assessed by potentiodynamic measurements, and bacteria-substrate interaction was followed by Atomic Force Microcopy (AFM).

The results revealed that the presence of pseudomona aeruginosa catalyze corrosion. The participation of catalase in increasing the cathodic reaction kinetics and consequently, the global corrosion process was demonstrated by electrochemical measurements using cobalt phtalocyanine modified electrodes, obtained in the absence and presence of the bacteria. In addition, from atomic force microscopy, bacterial cells within the biofilm exhibited high adhesion strength to the metal substrate. Corrosion events correlates with the hydrogen peroxide content in the crop and also, with the high adhesion of bacteria to the aluminium alloy surface.

When the aluminum alloy is coated with a polymeric film, synthesized by the mixing of Tetraethoxysilane (TEOS) and trietoxioctilsilano (TEOCS), surface examinations in the confocal microscope reveal that the polymer possess antibacterial ability against the bacteria. In addition, the electrochemical experiments show that the coating inhibits the microbiologically influenced corrosion on the alloy in 0.1 M NaCl. The nature of the antibacterial ability resides mainly in the hydrophobic characteristic of polymers and pH changes at the polymer-electrolyte interface.
Microelectrode Studies of Lithium Battery Materials
Authors: Clancy Tomas , Rohan James F.
Published: February 2020

Personal electronic devices rely on regular replacement of primary batteries or recharging of secondary batteries, requiring users to carry backup batteries or be tied to docking stations. A more desirable solution would be the integration of micro or nanosystems including energy storage with energy harvesting and the microelectronic devices to be powered. The autonomy of such devices requires the development of novel storage solutions for the scavenged or harvested energy. A truly autonomous device would have an on-device energy storage system that: (1) interfaces with various energy harvesting components, (2) provides power on demand to the electronic sensing, communication, and display components, and (3) retains its performance on charge and discharge cycling over the anticipated device lifetime.

In the typical 2D, thin-film geometry, lithium diffusion and poor electronic conductivity limits electrode thickness to micrometers and thus large surface areas resulting in a battery dominated by the substrate and other inactive cell components. Commercial thin film microbatteries are typically rated at <1 mWh/cm2. The target energy storage solution should occupy a volume no larger than the electronics it drives (sub <0.1 cm3) and be integrated on chip to store energy harvested at a level of 10 mW/cm2. Integrated electronic and energy devices for advanced micro and nanosystems technology therefore require energy sources with increased performance per unit substrate area. This requires not only structured electrodes to increase the surface area and quantitiy of active materials per unit footprint but materials with improved electronic characteristics for increased rate capabilities. In this work we will describe the results of core-shell lithium battery nanomaterials analysis at microelectrodes.
An AFM Evaluation of Rhenium-Nickel Electrodeposit Nucleation on Copper
Authors: Mondal Sujit Kumar , Contu Francesco , Ewers Bradly , Batteas James D , Taylor S Ray
Published: February 2020

The electrodeposition of rhenium and rhenium alloys is well documented both in acidic1-5 and alkaline6,7 solutions. The effect of complexing agents as well as the catalytic effect of divalent nickel ions has also been extensively investigated2-4. It has been shown that Re-Ni electrodeposits consist of alternating layers of Ni-rich and Re-rich phases2. However, a detailed explanation of the origin of such layers as well as the electrodeposit nucleation process is still missing. The objective of the present work is threefold. First, we seek to elucidate the nucleation mechanism of Re-Ni alloys. AFM will be used to document the formation and growth of electrodeposit nuclei and delineate the progressive vs. instantaneous nucleation mechanism. Second, the multilayered structure of the Re-Ni deposits will be addressed by documenting the formation of the initial layer and its evolution over time. Finally, nickel deposits will be used as substrates for pure rhenium electrodeposition to test the hypothesis that a strike layer of nickel is necessary to promote the deposition of pure rhenium.

Galvanostatic pulse methods were used to electrodeposit pure nickel and pure rhenium salts separately from citrate solutions on (111) single crystal copper substrates as well as mica-supported copper films. The results are compared with the electrodeposition behavior of Re-Ni bath mixtures. A very small time scale is needed to deposit a monolayer of nickel. Distinct differences in frictional force of the initial deposit nuclei was captured by AFM. Figure 1 shows the difference in frictional force between a bare copper surface (111) and nickel deposit on a copper (111) surface. Nickel was deposited electrochemically by exposing a copper surface (111) to a 96 mM nickel sulfamate solution under galvanostatic polarization for 1 ms at -53.0 mA/cm2. The spots observed in the frictional image are attributed to islands of nickel atoms that are too thin to be detected in the topography mode.

Acknowledgements

The authors gratefully acknowledge the financial support from AFOSR under grant FA9550-10-1-0520.

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Oxygen Involvement in the Charge Compensation of LiMO2 Compounds and the Consequences for Battery Safety and Unprecedented Electrical Magnetic Properties
Authors: Bogaert Kevin , Petersburg Cole , Buntin Parker , Greenlee Jordan , Doolittle W. Alan , Jaye Cherno , Fischer Daniel , Alamgir Faisal M
Published: February 2020

An intimate view of the operando electronic and atomic structure local to oxygen and transition metals in LiMO2 cathodes has been developed. We present here a combination of in-situ and operando measurements of structure, resistivity and magnetic susceptibility to expose the direct role of oxygen in charge compensation reactions. The formation of electron holes at oxygen sites, as detected by X-ray absorption spectroscopy (XAS), is a prerequisite for oxygen evolution reactions that can lead to battery fires. However, the same reaction, if managed well can lead to beneficial switching behavior of their magnetic and electrical properties. The magnetic susceptibility of LixCoO2 has been studied in composition range of 0.94 ≤ x ≤ 0.75. A consistent and linear increase in susceptibility with respect to decreasing lithium content has been observed with the notable exception of a sharp decrease in susceptibility at x = 0.94. This sharp change in molar magnetic susceptibility as well as the associated change in resistivity has potential use in neuromorphic memory applications.
Study of Loss Mechanisms in a Regenerative Hydrogen Vanadium Fuel Cell
Authors: Hewa Dewage Harini , Yufit Vladimir , Wu Billy , Tariq Farid , Cooper Samuel J. , Brandon Nigel P.
Published: February 2020

Development of renewable energies such as solar and wind power have received a great deal of attention. However, in order to utilise efficiently the power generated, it is essential to introduce energy storage systems at the grid level scale. Redox flow batteries are excellent candidates for this purpose as they present many potential advantages such as: decoupling of power and energy; modularity (kilowatts to megawatts systems); site independence; long cycle life and minimal maintenance.

But there remains scope to reduce the cost and improve the performance of current systems, and in this context a novel regenerative fuel cell, utilising an aqueous vanadium electrolyte and hydrogen gas has recently been reported1. The advantages offered by this approach are fast hydrogen kinetics, use of half of vanadium electrolyte in comparison to the conventional all vanadium flow battery and the absence of cross-contamination between the positive and negative half-cells.

The first generation of this vanadium-hydrogen cell assembled with commercial MEAs demonstrated a maximum power density of 107 mW/cm2 in a 1M V(IV)/V(V) solution. In this work we report improved performance to achieve a maximum power density of 229 mW/cm2 through cell design modification. Half-cell measurements have been used to gain a better understanding of the loss mechanisms in the cathode and anode. Additionally, the authors have implemented the use of 3D tomography to study the structural changes of carbon based electrodes over different numbers of experimental conditions (Figure 1). The latest results from these studies will be presented.

1 V. Yufit, B. Hale, M. Matian, P. Mazur and N.P. Brandon,
Development of a Regenerative Hydrogen-Vanadium Fuel Cell for energy storage applications
, Journal of The Electrochemical Society, 160 (2013), A856-A861.

Figure 1: 3D reconstructed image of a used SGL 10AA carbon electrode acquired using x-ray tomography. The volume represents a size of 211 x 749 x 914 μm3.
Performance Evaluation of the Non-Aqueous Vanadium Redox Flow Battery with Different Separators
Authors: Escalante-Garcia Ismailia L. , Wainright Jesse S. , Thompson Levi T , Savinell Robert F.
Published: February 2020

Non-aqueous redox flow battery (RFB) systems are being considered for grid-level energy-storage applications. Non-aqueous electrolytes exhibit wide electrochemical potential windows, generally > 2 V, which has a direct impact on the system energy and power density prospects. The increased cell potential is considered the primary advantage of non-aqueous RFBs over aqueous RFBs, which are limited by the electrochemical stability of water. Nevertheless, the development of non-aqueous RFBs is still at an early stage and thus significant research efforts are needed to achieve similar performance as in aqueous RFBs, especially, at the cell component level. The membrane or separator is one component that to a great extent affects the overall performance of RFB systems for practical applications. However, few reports have been found in the literature on the development and evaluation of separator materials for non-aqueous RFBs to date.

In this work, a small-scale redox flow battery prototype was designed to simulate energy storage and to evaluate the performance parameters of non-aqueous redox electrolytes. Cation exchanged Nafion® ionomer and microporous Daramic separators were prepared and investigated. A non-aqueous, single-metal redox flow battery based on vanadium (III) acetylacetonate (V(acac)3) with a thermodynamic potential of 2.2 V was considered. At least a 70-fold increase in charge/discharge current density was achieved by using modified Nafion® or a microporous separator compared with current literature. Coulombic and round-trip energy efficiencies of 70-90% and of 65-80%, respectively, were obtained depending on the separator. Both the modified Nafion® and microporous separators are promising options for non-aqueous redox electrolyte systems.
Electrochemical Characterization of Attached Marine Bioﬁlms for Application in MFC on Glassy Carbon/Carbon Nanotubes Scaffold
Authors: Galicia Monica , de Leon Judy Mildret , Rios Judith Virginia , Castaneda Homero
Published: February 2020

Glassy carbon electrode modified with multiwalled carbon nanotubes (MWCNT) and chitosan (Chit) is tested for the biofilm attachment and electron transfer by using electrochemical techniques. This work describes the electrochemical and high surface resolution of multiwalled carbon nanotubes (MWCNT) coupled to chitosan by using Cyclic Voltamperometry (CV) and Electrochemical Impedance Spectroscopy (EIS). Confocal microscopy is used to characterize the growth of thin bioﬁlms onto this 3D macroporous scaffolds and to corroborate the insights determined by electrochemical tecnniques. CV and EIS also reveal features that are consistent with detections of multiple redox-active species appearing in this biofilm and associated to electron transfers. These techniques depicts specifics quantiﬁable characteristic and deﬁned electron transfer processes as a function of potential, electrode material, growth phase for biofilms derived from marine sediments and marine waters.
(Technology Award of the Battery Division) An Overview of New Technologies and Related Materials Research and Development for Rechargeable Batteries in China
Authors: Wu Feng , Li Li , Wu Chuan
Published: February 2020

Global concerns on environmental pollution, greenhouse gas emission, and climate changes are making the developments of renewable energy technologies and deployments a priority. Rechargeable batteries and related materials research and development are key to enabling the renewable energy technology deployments, playing an important role. Since China is one of the largest energy consumers in the world today, largely driven by the fast growing domestic utility and automobile market sectors, the strategic planning and policy implementation for rechargeable batteries R&D in China are receiving more worldwide attention.

Here an overview on the research and technology development of rechargeable batteries in China is first presented, followed by a few examples of recent results obtained in our laboratories that are unique to represent the existing efforts and directions. These battery-related technology research and development activities include new generations of functional electrolytes; new reinforced composite polymer electrolyte membranes to improve the safety and thermal stability of lithium ion batteries; multi-valence electrode systems for the next generation of high-energy-density batteries; as well as the bioleaching technology to effectively extract transition metals from the scrapped lithium-ion batteries.
(Outstanding Achievement Award of the Sensor Division) From Antibody to X-ray 25 Years in MEMS Sensors
Authors: Hesketh Peter
Published: February 2020

Micromachining silicon with anisotropic etching solutions has been a core technology in MEMS for over twenty years and resulted in some novel structures including high emissivity surfaces to increase heat transfer and X-ray focusing devices built for Argonne National Laboratories. A key challenge in biosensing is achieving selectivity which is often provided by immobilizing antibodies at an electrode surface or on a magnetic bead for preconcentration of a target. Impedance based sensing for low power, and direct detection of microbial toxins was studied at porous platinum electrodes, at the University of Illinois at Chicago and Illinois Institute of Technology. This method can be compared with energy generation by enzymes using thermopiles, such as glucose sensors, and redox recycling at interdigitated electrode arrays for the detection of cytokines in a sandwich assay. We are currently investigating methods to improve sampling and pre-concentration through efficient bead-based manipulation using rotating magnetic fields. The use of a CD platform with centrifugal micro-fluidic pumping system will also provide a high throughput approach for target capture using magnetic beads. Manipulation of fluid transport using magnetic bi-directional latching microvalves was investigated for direct methanol fuel cells and miniature gas chromatography systems. The control of sample injection is a critical component of GC systems. Miniature GC columns with integrated heaters have now been developed to improved separation efficiency. These systems show great promise for low power portable chemical analysis systems. Low power sensors are needed, which can include cantilever sensors possessing exquisite sensitivity for chemical detection. We have investigated metal organic framework films, a nanoporous coating, in collaboration with Sandia National Laboratories, on cantilever sensor for detection of VOC’s. This mechanical based detection approach shows improved reproducibility and stability while using minimal power. MEMS accelerometers and gyroscopes are now in most cell phones, while ultra-low power chemical sensors are yet to be integrated. However sensors based upon changes in the thermophysical properties of gases, under development in collaboration with KWJ Engineering, may soon provide gas detection to monitor the environment, improve safety, and even provide breath analysis for heath care.
Hybrid Porous Silicon- Rhodamine B Derivative Nanostructures as Chemical Sensor for Hg(II) Detection
Authors: De la Cruz Guzman Paola Mayela , Aguilar-Aguilar Angelica , Bañuelos-Frias Alan , Chazaro-Ruiz Luis Felipe , Palestino Gabriela
Published: February 2020

In this work we propose a new method to produce a fluorescent chemical sensor for mercury detection (Hg(II)). This device is mainly based on the optical properties of porous silicon nanostructures (PSi) [1] coupled with the fluorescent properties of Rhodamine B [2] (Rh-urea-Ph-urea-Si) ligand derivative, which is covalently linked to PSi acting as receptor of metal ions. The Rh-urea-Ph-urea-Si (Ph=Phenil) compound was synthesized and its complexing ability was studied in liquid phase and solid by fluorescence spectrometry. The results showed that the fluorescence response of the metallic complex is metal concentration dependent. If the Hg(II) concentration increases, the florescence intensity also increases to reach the saturation point of the fluorophore. The electrochemical etching of crystalline silicon wafer [3] produced the PSi transducers, which in turn were functionalized with the organic receptors. The ligand infiltration into the PSi matrix and the metal coordination on the hybrid substrate were evaluated by specular reflectance, infrared and fluorescence spectroscopy, and SEM. Fluorescence microscopy confirmed the qualitative detection of Hg(II) ions due to the increase of the fluorescence observed after metal capture. The changes in electrical impedance upon porous silicon samples before and after the chemical modification, allowed us to obtain the approximate surface area of the porous devices. During the presentation of this work, the Hg (II) detection through voltammetric techniques will be discussed.

Acknowledgements.

This work was supported by the CONACYT, Project No. CB-153161 and 169634. P Mayela De la Cruz thanks the

CONACYT Scholarship: 237466. We acknowledge to Olga Dávalos Montoya for FTIR support and Prof. Jaime Ruiz for the facilities provided for the use of the fluorescent microscope.

References.

[1] A. Melek, D. Wissem, M. Ghrib, C. Radhouane, Ezzaouia. Journal of Luminescence. 132 (2012) 277-281.

[2] Zhisheng Wu, Xuanjun Wu, Yuhui Yang, Ting-bin Wen, Shoufa Han, Bioorganic & Medicinal Chemistry Letters. 22 (2012) 6358–6361.

[3] G. Palestino, M. Martin, V. Agarwal, R. Legros, T. Cloitre, László Zimanyi, C. Gergely, Phys. Status Solidi C. 6(7) (2009) 1624-1628