bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Behavior of Toluene in Adiponitrile
Authors: Cheek Graham T.
Published: February 2020

Introduction

Previous studies from this laboratory have involved the characterization of adiponitrile (NCCH2CH2CH2CH2CN) / tetraethylammonium tetrafluoroborate (TEABF4) as a versatile solvent system for organic electrochemistry (1,2). One very valuable feature of this system is the wide potential limit range, as noted by others (3). Considering that the positive potential limit is +5 V vs Ag/AgCl, the system is particularly attractive for the study of hydrocarbon oxidation. The present paper is a continuation of the study of various hydrocarbons in adiponitrile (4).

Experimental

Adiponitrile was obtained from Sigma-Aldrich Corporation, and tetraethylammonium tetrafluoroborate (TEA BF4) was purchased from Southwestern Analytical Chemicals. Cyclic voltammograms were obtained on a PAR 283 potentiostat using PowerSuite software. Potentials are referenced against a Ag/AgCl reference electrode (1). Platinum and glassy carbon electrodes (1 mm diameter each) were obtained from eDAQ.

Results and Discussion

Cyclic voltammograms of 6.8 mM toluene in adiponitrile / 0.2 M TEABF4 are shown in the attached figure. An initial positive scan at platinum from 0.00 V produced a multicomponent, irreversible oxidation process between +2V and +3V vs Ag/AgCl, with considerable current on the second sweep (not shown). Results at glassy carbon were somewhat similar; however, there is little evidence of multiple oxidation processes. In addition, the lack of oxidation current on the second sweep at glassy carbon indicates that considerable electrode filming at glassy carbon is involved. Reported peak potentials in acetonitrile / NaClO4 are similar to the values observed in the present study (5). This study shows that adiponitrile / 0.2 M TEA BF4 is a useful solvent system for the electrochemical study of toluene.

References

G.T. Cheek, ECS Trans., 58(46), 45-51 (2014).

G.T. Cheek, ECS Trans., 61(30), 19-24 (2104).

H. Duncan, N. Salem, and Y. Abu-Lebdeh, J. Electrochem. Soc., 160(6) A838-A848 (2013).

G.T. Cheek, ECS Trans., 72(26), 1-5 (2016).

W.C. Neikam and M.M. Desmond, J. Am. Chem. Soc., 86, 4811-4814 (1964).

Figure 1. Cyclic voltammograms of 6.8 mM toluene in adiponitrile / 0.2 M TEA BF4 at 100 mV/s.

Black (solid) curve : Platinum ; Red (dotted) curve : Glassy carbon

Figure 1
Invited: Efficient Proton Transport in Rhodopsins Biohybrid Electrochemical Materials and Systems
Authors: Xiang Yan
Published: February 2020

Efficient and directional proton transport is a very necessary energy conversion step whatever in biochemical process and artificial electrochemical energy systems. Microbial rhodopsins photosynthesis is an extremely simple but efficient natural light-driven proton pump energy conversion system. With advanced materials science and manufacturing engineering, the biohybrid nanosystems based on microbial rhodopsins and functional materials have been paid much attention.

In past five years, we devote ourselves on hybrid nanosystem through the integration of proton pump microbial rhodopsin, bacteriropoin(bR) and proteorhodopsin (pR), with functional materials for energy conversion, sensoring and artificial version studies. We focus on the artificial use of bR and pR photoelectric energy conversion through enhancing photocurrent density and enriching photocurrent waveform. Surface plasmonic effect of Au nanoparticles and proton conductor assisted 3D proton transfer have successfully improved bR and pR photocurrent, and greatly ameliorate the photoelectric performance [1, 2]. Inspired by the plasma membrane capacitor-like behavior, we developed a pR bio-capacitor system and regulated photocurrent duration time (PDT) through nanochannel resistance. Consequently, pR original transient photocurrent has been transformed into square-like waveform, which would be of broad use in further nanoenergy conversion [3, 4]. Taking advantage of pR pH-dependent photoelectric characteristics, a pR-hybrid pH sensor has achieved real-time pH detection with quick response and high sensitivity [5]. Recently, bR and pR frequency-responsive characterization was identified in the as prepared photoelectric system and further introduced to construct artificial vision [6]. Moreover, particular effort has been paid on the cooperation and adjustment between bio-components and functional materials. These original findings improve the perception on rhodopsin protein and provide mechanism insights from pure biophysical studies into the design and regulation of artificial biohybrid devices.

References:

1. Z. Guo, D. Liang, S. Rao and Y. Xiang, Nano Energy, 2015, 11, 654-661.

2. S. Rao, Z. Guo, D. Liang, D. Chen and Y. Xiang. Advanced Materials, 2015. 27(16): 2668

3. S. Rao, S. Lu, Z. Guo, Y. Li, D. Chen and Y. Xiang, Advanced Materials, 2014, 26, 5846-5850.

4. S. Rao, K. J. Si, L. W. Yap, Y. Xiang, and W. Cheng, ACS Nano, 2015, 9 (11), 11218– 11224

5. S. Rao, Z. Guo, D. Liang, D. Chen, Y. Wei and Y. Xiang, Physical Chemistry Chemical Physics, 2013, 15, 15821-15824.

6. S. Lu, Z. Guo, Y. Xiang, L. Jiang, Advanced Materials, DOI: 10.1002/adma.201603809
Orientational Control of Photosystem I on Electrodes
Authors: Cliffel David E , Gizzie Evan Alexander , Bryant Carson J
Published: February 2020

In our continuing quest to control the orientation of redox-active proteins on electrode surfaces, we have focused on chemical reactions at the lysine groups of Photosystem I while it is still part of the thylakoid membrane. The functionalization of protein complexes while still part of their native membrane can be confirmed by conventional analytical methods. After extraction of the now labeled stromal side of the photosystem I protein complex, we have explored a number of methods for achieving electron transfer directly through the orientated protein complex. These alternatives to direct chemisorption on surfce includes nanoparticle conjugation and other chemical reactions that take advantage of the chemical transformation on the stromal side. These advances will be detailed in this presentation.
Real-Time Monitoring of NADPH Oxidase Inhibitory Effect of ROS Production from THP-1 Cells Using Iron-Porphyrin Modified Carbon Electrode
Authors: Kasai Shigenobu , Prasad A. , Matsuoka R. , Takahashi A. , Nakagawa Atsushi , Sugiura Yamato , Koriyama Hiroki , Aoyagi S. , Aikawa T. , Kondo T. , Yuasa M.
Published: February 2020

Immune cells such as monocytes and neutrophils responds to external stimuli and during the invasion by foreign body undergoes phagocytosis during which reactive oxygen species (ROS) such as superoxide anion radical (O2
•−), hydrogen peroxide (H2O2) and hydroxyl radical (•OH) are produced. The iron-porphyrin modified carbon electrode is prepared by the electropolymerization of 1-methylimidazole-coordinated iron meso-tetra (3-thienyl) porphyrin ([Fe(im)2(ttp)]Br) [1].

The detection of O2
•− is based on amperometry comprising of counter electrode and working electrodes. The counter electrode is a platinum plate (2.5×2.5mm) while the working electrodes (φ1mm) is an iron-porphyrin modified carbon electrode. Ag/AgCl was used as a reference electrode. The iron-porphyrin modified carbon electrode acts as O2
•−detection sensor (Fig. 1).

The O2
•− generation was measured in THP-1 cells (cell lines of myeloid leukemia patients) under the effect of differentiation inducer phorbol 12-myristate 13-acetate (PMA) in the absence and presence of exogenous addition 0.1 wt% Triton X at 25°C at a cell density of 3.0 × 106 cells/well. Triton X is known to permeabilize the membranes of living cells. The results obtained showed no considerable changes in reduction currents for O2
•− under the effect of inducer (PMA). However, the addition of Triton-X showed a fast increase in oxidation current for O2
•− by about approximately 2 nA followed by a gradual drop which continued for a time span of more than 3 hours. We further investigated the effects of inhibitors for the activity of NADPH oxidase that catalytically produce ROS; apocynin were selected as inhibitors of NADPH oxidase [2].

The production of O2
•−of real-time monitoring of NADPH oxidase inhibitory effect of PMA induced THP-1 cells using iron-porphyrin modified carbon electrode were detected by amperometory. The results shown in Fig.2 suggests that amperometory is mainly derived from the O2
•−,whose expression is induced by NADPH oxidase.

[1] M. Yuasa et al. Polym. Adv. Technol. 16 (2005)287–292.

[2] S.Kasai et al. Analytica Chimica Acta 549 (2005)14-19.

Figure 1
Bactosomal Bioelectrode Design on a Cysteamine Self-Assembled Monolayer
Authors: Krishnan Sadagopan , Nerimetla Rajasekhara
Published: February 2020

We discuss here real-time monitoring of the formation of biocatalytically active films of membrane-bound human cytochrome P450 3A4 expressed with its reductase in E. Coli (so called bactosomes) on a cysteamine self-assembled monolayer of gold infused quartz crystals. Amount of immobilized P450 3A4 bactosomes was 471±21 μg cm–2 gold geometric area (N = 3 replicates). Scanning electron microscopic and impedance characterizations of the constructed P450 bactosomal films, electrocatalytic oxygen reduction activity, and voltage-driven (–0.6 V vs. Ag/AgCl, 1 M KCl) C-H functionalization of diclofenac to 4-hydroxydiclofenac typical of P450 3A4 catalysis are presented. The formation of 4-hydroxydiclofenac in the presence of added catalase (hydrogen peroxide scavenger) to the electrolysis solution suggested the reductase pathway of P450 3A4 catalysis followed in the designed bactosomal film, which is similar to the in vivo catalytic mechanism. This one-step construction of biocatalytically active films of cost-effective P450 bactosomes is quite useful for low cost, stereoselective, and NADPH-free drug metabolism assays, biosensing, and biocatalysis applications.
Nano/Micro Fabricated Sensor Chips for Human Sensing Platform
Authors: Li Li , Kelley Thomas , Shin Minchul , Burgess James
Published: February 2020

This research team is further developing a platform for electrochemical based human bio-sensing. Past work by this research group has demonstrated the ability to monitor the rate of cholesterol extraction from the cell plasma membrane at cholesterol oxidase modified microelectrodes positioned in contact with the cell surface. The electrode creates a local demand for cholesterol by enzymatic consumption and the flux of cholesterol to the electrode is measured. Studies at single cells and at mouse tissues show that the cholesterol efflux rate is elevated at cystic fibrosis samples relative to wild-type controls. In extending the measurement to human subjects, a double potential pulse data acquisition method was demonstrated where hydrogen peroxide from enzymatic cholesterol oxidation is allowed to accumulate prior to oxidation by potential pulse. A second pulse provides a unique background that is subtracted for evaluation of the amount of hydrogen peroxide. To increase signal to noise so that human measurements may be conducted without a faraday cage, micro/nano sensor chips have been produced that are composed of an array of separated, micron-sized regions containing immobilized enzyme as well as nano-platinum electrodes for oxidation of hydrogen peroxide. Characterization and performance of the sensor chips will be discussed.
Selective Nanomaterials for Glucose-to-Gluconate Oxidation in an Electrochemical Energy Converter: Cogenerating Organic Electrosynthesis
Authors: Holade Yaovi , Servat Karine , Napporn Teko W. , Kokoh Kouakou Boniface
Published: February 2020

Glucose is an environmentally friendly and sustainable carbohydrate that is actually a cyclized aldehyde in aqueous solution i.e. a hemiacetal. Its selective oxidation by the anomeric carbon in C1-position without any function protection is of great interest for cogeneration because the electrochemical process enables converting this highly functionalized organic molecule into electricity, heat and added-value chemicals. For this objective, we decided to synthesize effective nanomaterials towards glucose conversion at the anode and the oxygen reduction reaction (ORR) in the cathodic side of a fuel cell. The physical characterizations of the prepared materials and their electrochemical analysis at each half-cell, permitted to optimize the activity of the electrodes according to their elemental composition and structure. Furthermore, a constructed direct glucose fuel cell (DGFC) delivered an open-circuit voltage of 1.1 V in 0.5 mol L‒1 NaOH and an outstanding output power of 2 mW cm‒2 in 0.5 M KOH (Figure 1a). Complementary analytical techniques were employed to quantify the reaction processes involved in each compartment, to determine the reaction products resulted from the glucose transformation and thereby, to understand reaction mechanisms of the glucose oxidation and the ORR over the synthesized electrode materials used in alkaline medium. As results, the identification of gluconate as the sole reaction product in the anodic side showed a selective 2-electron conversion of glucose (Figure 1b), while the ORR proceeded through a 4-electron pathway over the designed cathode catalyst (Figure 1c).

Figure 1: (a) Fuel cell polarization curves for different concentrations of glucose in a single fuel cell. Anode: 20 wt.% Au/C (0.18 mgAu cm‒2); cathode 20 wt.% Pt/C (0.17 mgPt cm‒2); Fumatech AEM. Anode: 0.5 mol L‒1 KOH + glucose (deoxygenated by N2); cathode: 0.5 mol L‒1 KOH + O2. (b) LC–MS negative ionization mass spectrum (M-1) of the product. (c) Electrochemical durability tests: Comparison of the ORR polarization curves (at 5 mV s−1) before (black) and after 1000 CVs (red); insets show the normalized specific electrochemical active surface area (SECSA) decay over the 1000 cycles from 0.05 to 1.1 V vs. RHE at 50 mV s−1.

Acknowledgments

The authors gratefully acknowledge financial support from the French National Research Agency ANR-ChemBio-Energy

 

References

1. Y. Holade et al., ChemSusChem, 9, 252 (2016).

Figure 1
Electrochemical Imaging of Copper Contamination on Self-Assembled Organic Monolayer Modified Silicon Surfaces Following a ‘Click’ Reaction with Light-Addressable Potentiometric Sensors and Scanning Photo-Induced Impedance Microscopy
Authors: Wu Fan , Watkinson Michael , Krause Steffi
Published: February 2020

Light-addressable potentiometric sensors (LAPS)1 and scanning photo-induced impedance microscopy (SPIM)2, both of which are based on photocurrent measurements at electrolyte /insulator /semiconductor (EIS) field-effect structures can be used to detect local surface electrical potentials and impedance, respectively. While LAPS measures local potential changes by recording the shift of the photocurrent-voltage (I-V) curve along the voltage axis, SPIM records changes in the maximum photocurrent while the EIS structure is biased towards inversion. Both techniques have been extensively applied for chemical ion sensing, biosensing, and the investigation of cell metabolism, extracellular potentials, cell surface charge and impedance. Importantly, they have been reported to be highly sensitive to the surface contamination on self-assembled organic monolayers3.

In this work, a copper (I) catalyzed azide alkyne cycloaddition (CuAAC) reaction, combined with microcontact printing was employed successfully to pattern alkyne-terminated self-assembled organic monolayer modified silicon surfaces (Figure 1a). Despite the absence of a copper peak in XPS spectra, copper contamination was found and visualized using LAPS and SPIM, after the ‘click’ modified silicon surfaces were rinsed with hydrochloric acid solution (Figure 1b), which has been frequently used to remove copper residues in the past. Different strategies for avoiding copper contamination, including the use of bulky chelators for the copper (I) catalyst and rinsing with different reagents, were tested. Only cleaning of the silicon surfaces with an ethylenediaminetetraacetic acid (EDTA) solution after the ‘click’ modification proved to be an effective method as confirmed by LAPS and SPIM results, which showed the desirable electrical properties (surface charge and impedance) of an organic monolayer (Figure 1c).

1. Hafeman, D. G.; Parce, J. W.; McConnell, H. M., LIGHT-ADDRESSABLE POTENTIOMETRIC SENSOR FOR BIOCHEMICAL SYSTEMS. Science
1988,240, (4856), 1182-1185.

2. Krause, S.; Talabani, H.; Xu, M.; Moritz, W.; Griffiths, J., Scanning photo-induced impedance microscopy - an impedance based imaging technique. Electrochim. Acta
2002,47, (13-14), 2143-2148.

3. Wang, J.; Wu, F.; Watkinson, M.; Zhu, J. Y.; Krause, S., "Click" Patterning of Self-Assembled Monolayers on Hydrogen-Terminated Silicon Surfaces and Their Characterization Using Light-Addressable Potentiometric Sensors. Langmuir
2015, 31, (35), 9646-9654.

Figure 1
Electrolytes Related Dynamic Mechanical Properties of Nanoconfined Water
Authors: Khan Shah Haidar , Hoffmann Peter Manfred
Published: February 2020

Charged surfaces and electrolytes play an important role in many scientific and technological applications such as molecular friction, transport through bio-membranes, and generation of electrochemical energy. Using a home-built ultra-sensitive atomic force microscope, we have measured the stiffness, damping coefficient, and Maxwell’s relaxation time of a few molecular layers thin film of electrolytic water against atomically smooth mica surface. Water containing NaCl and CsCl have been compared with ultrapure water. The viscoelastic properties of the nanoconfined film exhibit a strong dependence on the compression rate of the film as well as the type of electrolyte present. The increase in Maxwell’s relaxation time as a function of NaCl concentration gives rise to a solidlike dynamic mechanical response under quasi-static conditions (compression rate = 0.2 nm/s). In contrast, the CsCl containing electrolytic water seems to suppress the solidlike dynamic mechanical behavior, which results from an apparent jamming of the molecules during a squeeze-out, as suggested elsewhere (Khan et al., Phys. Rev. Lett. 2010). These results suggest that the size and hydration number of ions play an important role in nanoconfined water.
Highly Branched Poly(ethylene oxide) for Solid Electrolytes
Authors: Paranjape Nachiket , Lin Haiqing , Wu Gang , Mandadapu Praphulla
Published: February 2020

Commercial Li ion batteries use liquid electrolytes between the electrodes to obtain good Li ion conductivity and thus good energy density. However, the liquids are highly flammable, which presents a great challenge in designing large scale batteries. Solid polymer electrolytes (SPEs) based on poly(ethylene oxide) (PEO) have been widely explored as an alternative of all-solid-state Li ion batteries. However, their wide adoption is prohibited due to their low conductivity at room temperatures (lower than 10-5 S cm-1), presumably because PEO is semicrystalline and crystals may not be available for ion conductivity. The goal of this study is to design and prepare series of polymers containing amorphous PEO with high free volume, achieving higher Li ion conductivity than the semi-crystalline PEO. Specifically, polymers were prepared using UV photopolymerization from poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) methyl ether acrylate (PEGMEA). The addition of PEGMEA in PEGDA increases the free volume and polymer chain flexibility. Polymer electrolytes based on PEGDA-co-PEGMEA and lithium perchlorate (LiClO4) have been prepared and characterized using DSC, WAXD and electrochemical impedance spectroscopy (EIS). At PEGMEA content of 90% in the polymer with an O:Li ratio of 14, the conductivity approaches the current industrial targeted value (10-5 S/cm), which is two orders of magnitude higher than that of pure PEO. This presentation will also compare the results with those based on the PEO-containing materials using the Vogel-Fulcher-Tammann (VFT) equation. The implication of the VFT model on the potential of PEO-based SPEs in terms of ionic conductivity will be elucidated.
Sulfonated Block Copolyphenylchinoxalines As Proton Exchange Membranes
Authors: Janietz Silvia , Egorov-Brening Tatjana
Published: February 2020

The proton exchange membrane fuel cell (PEMFC) is considered to be the most promising power source for portable and automotive applications. Currently, perfluorinated polymers such as Nafion are the state of the art materials because of their good physical and chemical stability along with high proton conductivity under a wide range of relative humidity at moderate operation temperatures. However, high operation temperatures, cause weakening of their properties. In addition, their shortcomings such as high cost and high methanol permeation property, limit their application. To remedy these problems, aromatic hydrocarbon polymers have been extensively studied as alternative materials for proton exchange membranes (PEMs)and many sulfonated aromatic polymers such as poly(phenylene)poly(ether ether ketone)s, poly(ether ether sulfone) poly(arylene ether) and polyimides have been developed as alternate candidates. Generally, membranes based on these polymers can achieve high proton conductivity by increasing their ion exchange capacities (IECs), resulting in huge water uptake and a dramatic loss of mechanical properties. Recently, introduction of block copolymer structures to PEMs has been considered as a strategy to overcome the weak points of a random copolymer system. Block copolymers composed of hydrophilic and hydrophobic segments are expected to form ion transport channels due to hydrophilic/hydrophobic phase separated structures and show improved proton conductivity. Poly(phenlyquinoxalines) are a family of aromatic condensation polymers known their outstanding thermal and chemical stability. Based on this polymer class new sulfonated block copolyphenylchinoxalines with hydrophilic and hydrophobic segments have been developed. The block copolymers were synthesized via polycondensation reactions between 3,3`-4,4`tetraaminodiphenylether and two different tetracetones, followed by sulfonation using a mixture of concentrated sulfuric acid. and oleum (4:1).High molecular-weight polymers over 20 000 in number average molecular weight were easily obtained and gave tough and flexible membranes by solvent casting. The properties of their membranes, such as proton conductivity, water uptake, oxidation and dimensional stability were investigated und presented.
Measurement of Thickness of High-Resistivity Substrate By Photoconduction Enhanced Capacitance Displacement Sensor
Authors: Lee T. -H. , Lin M. -C.
Published: February 2020

Capacitive displacement sensors can offer non-contact, extreme resolution, and absolute accuracy thickness measurements. However, for general capacitive displacenent sensors, if the resistivity of a target substrate is within 105-107 ohm-cm, a measurement uncertainty will occur in the thickness measurement. The measnurement uncentration may be several microon meters. The common solution is to adjust the resistivity to be outside the range that causes the measurement uncertainty by implanting dopants and followed by an activation anneal, but this will unavoidably lead to changes in the material properties and morphology. Here, we exploit the photoconductive effect to generate sufficient high amount of electron-hole pairs, thereby temporarily decreasing the resistivity and thus enabling the capacitive displacement sensor to accurately measure the thickness at nanoscale resolution. After the measurement is complete, the resistivity of the substrate will return to its original status. The photoconductive effect can be simply induced via laser irradiation at the sensing point, which narrows or eliminates the gap in the measurement range of capacitive sensors to include high-resistivity substrates.
Electrooxidation of Hexacyanoferrate(II) Anions in the Microfabricated Electrochemical Sensor-Array System
Authors: Pitman Kätlin , Nerut Jaak , Lust Enn , Raud Merlin , Kikas Timo , Franssila Sami
Published: February 2020

The field of application of micro-electrodes is very wide: from electroanalytical applications (detection of ultra-low quantities of analyte, biosensors, etc.), kinetic studies of very fast and complex reactions, to measurements in solutions of very low conductivity, etc.1-3 Often several micro-electrodes are combined into sensor-arrays for simultaneous analysis of various parameters.

In this work the microfabrication technique was used to prepare a six-channel sensor-array chip.4 The sensor-array has been fabricated of borosilicate wafer containing Pt electrodes and connection pads and the silicon wafer with through holes, which were bonded using adhesion bonding method with SU-8. Although the fabrication process of two wafers is simple, the extensively perforated silicon wafer is brittle and can break down during bonding step. However, with the customized bonding process, a good bonding was achieved and all the chips were applicable after dicing.

The cyclic voltammetry and electrochemical impedance experiments were carried out in a three-electrode electrochemical system to characterize the prepared sensor-array chips. Sputtered platinum was used for micro-electrodes, and Ag/AgCl/sat. KCl as a reference electrode. The high surface area Pt counter electrode has been used for studies.

It was shown that the measured current density depends on the electrode potential sweep rate, however both linear and radial diffusion mass transfer components are important at high electrode potential scanning rate. When using slow potential sweep rates (v = 0.005 V s‒1) the pseudo steady-state has been achieved and the electrodes behaved as the micro-electrodes. It was shown that the pseudo steady-state current density depends linearly on the concentration of potassium hexacyanoferrate(II) in the 1.0 M KCl aqueous solution.

Based on the electrochemical characterization data it can be concluded that the produced sensor array is suitable for future research including BOD biosensor-array construction. The sensor-array developed can be modified with microorganisms by immobilizing the bacteria into the cavities fabricated onto/into the chip.

Acknowledgements

This research was supported by the EU through the European Regional Development Fund (Centre of Excellence, 2014-2020.4.01.15-0011), Institutional Research Grant IUT20-13, and Estonian Science Foundation (Grant ETF 9136).

References

1. J. Heinze, Angew.
Chem. Int. Ed. Engl., 32, 1268 (1993).

2. A.M. Bond, Analyst, 119, 1R (1994).

3. A. J. Bard and L. R. Faulkner, Electrochemical methods: fundamentals and applications, John Wiley & Sons Inc., New York (1980).

4. K. Pitman, M. Raud, G. Scotti, V.P. Jokinen, S. Franssila, J. Nerut, E. Lust, and T. Kikas, Electroanalysis (2016). Published online (DOI: 10.1002/elan.201600559).
Autonomous Silicate Electrochemical Sensor in Seawater
Authors: Chen Legrand Dancheng , Barus Carole , Striebig Nicolas , Garcon Véronique
Published: February 2020

Long term monitoring of dissolved inorganic nutrient concentrations such as silicate is the key to improve our understanding of biogeochemical cycles in the ocean. Electrochemical methods are proposed to measure in situ silicate concentration as they allow to develop miniaturized, reagentless sensor. We report here on the development and the optimization of the in situversion of our silicate sensor.

Silicate is a non-electroactive specie and its determination is performed by measuring its corresponding silicomolybdic complex formed in situ at acidic pH after the oxidation of a molybdenum electrode while the counter electrode is isolated behind a Nafion® membrane [1].

The mechanical design of the sensor has been adapted from the laboratory prototype containing two connected cells: one for the complexation and one for the detection on a gold electrode (Æ=2mm) by cyclic voltammetry. All the electrochemical and chemical parameters, such as the Mo oxidation, the complexation time, the silicomolybdic complex detection as well as the complex transfer from one cell to the other and the cleaning protocol have been optimized to detect the smallest silicate concentration possible with the shortest time. Reproducible calibrations performed with this sensor provided linear regressions between 2.5 µmol L-1 and 70 µmol L-1 and a limit of detection of 1 µmol L-1.

The 1st version of the sensor has been validated so far down to 50 meters using a pressure column and deployed in the Kiel fjord (Baltic Sea, Germany) down to 25 meters. The electronics (including datalogger) was also validated in situ as well as the solenoid pump placed into an equi-pressure compartment filled with dielectric oil. Some mechanical improvements have been done and the 2ndversion of the silicate sensor is currently in fabrication. This new version will be deployed off Chile (South of Coquimbo) in April 2017 and results obtained will be discussed.

[1] Lacombe et al., Talanta 77 (2008) 744-750.
Sensitive Double-Layer Coil Detector for the Detection of Salmonella Typhimurium Using Magnetoelastic Biosensors
Authors: Liu Yuzhe , Du Songtao , Horikawa Shin , Chai Yating , Wikle Howard Clyde , Suh Sang-Jin , Chin Bryan Allen
Published: February 2020

The design, simulation, fabrication, and characterization of a highly sensitive double-layer coil detector, utilized with magnetoelastic (ME) biosensors to detect bacterial pathogens, is presented in this paper. The former coil detector was a single-layer coil employed to realize wireless Salmonella detection on various food surfaces, while the double-layer coil in this work has enhancement in sensor excitation and detection sensitivity. With the double-layer coil, not only the wireless detection distance can be further, but also a smaller ME biosensor can be used in the detection to provide higher mass sensitivity. Various coil design parameters, including the thickness of layers, width, height, and spacing of coil turns, were studied. Both theoretical calculations and experimental data showed that the above parameters have a significant impact on the signal amplitude and stand-off distance. Finally, with the newly fabricated double-layer coil detector, detection of Salmonella Typhimurium using multiple biosensors on a food grade Ultra-high-molecular-weight polyethylene (UHMW-PE) board surface was demonstrated. This double-layer coil detector, therefore, facilitates the detection of pathogens on food and food contact surfaces.
Combining Electrochemistry and Biology to Create a Suite of Portable Biosensors for Water Analysis
Authors: Mayall Robert Matthew
Published: February 2020

Water analysis is a complex process requiring sample preparation, shipping, and analytical machinery. Often this process is removed from the individuals who require the test results. FREDsense Technologies is developing a platform sensor system for the fast and efficient analysis of water chemistry using biosensors. By combining biology and electrochemistry, microbes can be utilized to specifically measure a variety of different chemical compounds. FREDsense has demonstrated the efficacy of the platform through the development of an arsenic sensor (FRED-As) and FREDsense aims to commercialize and launch this product for near real-time arsenic analysis in the field.

The FRED system works through genetically engineering bacteria such that when they encounter a contaminant of interest they cleave a substrate in proportion to the target compound to produce a redox active species. This species then diffuses to a screen-printed carbon electrode surface to undergo a reversible oxidation detected either via cyclic or square wave voltammetry. This use of bacteria as an intermediary in the detection of compounds of interest creates a large signal amplification, as trace quantities of pollutants (low ppb) can be translated into the production of currents that are easily detectable on an inexpensive handheld potentiostat system (< $100).

To date, this system has been shown to respond reliably to single ppb levels of As (III) in under an hour in a laboratory setting, with field trials currently underway in multiple locations. This is coupled with an inexpensive and easy to manufacture potentiostat system running open-source software. This system is also expandable to detect other contaminants through the implementation of different genetic circuits, producing a selection of bacteria that can be chosen to monitor the varied needs of unique testing locations. Combined, this creates a powerful platform technology that can simplify the water analysis process for a variety of industries.
Sensitive Colorimetric Detection of Nitrite Ions Based on the Aggregation of Gold Nanoparticles
Authors: Kulkarni Aniruddha , Bird Victoria , Ziegler Kirk J
Published: February 2020

Determination of nitrite both environmentally and in life processes has been of importance as its presence above a threshold causes detrimental effects. Hence, there is a need to develop new, simple and highly sensitive analytical assays. Nitrite detection has been achieved through various methods, including chemiluminescence, electrochemistry, and surface-enhanced Raman scattering which involve use of expensive equipments, tedious procedures and time consumption.

However, colorimetric assays can provide visual, on-site analysis, providing a simple and instantaneous detection method. In this work, a facile colorimetic assay has been proposed based on anti-aggregation of gold nanoparticles. Gold nanoparticles coated with aromatic amines react with nitrite ions that alter the aggregation state of the nanoparticles. The change to the aggregation state causes a shift in the local surface plasmon resonance bands, triggering a colorimetric response. An increase in the concentration of nitrite ions changes the color of the solution, which can be detected by the naked eye.

While many approaches have used thiol-based linkers, our use of disulphide cross-linkers, which bind more strongly to gold has increased the sensitivity of detection by an order of magnitude. Furthermore, the effect of this assay on synthetic urine has been explored to understand the effect of the presence of foreign ions on the detection of nitrite.

Keywords: Anti- aggregation, gold nanoparticles, surface plasmon, aromatic amines
Interactions of TiO2 Nanotubes with Contaminants of Emerging Concern for Applications in Point-of-Use Electrochemical Detection
Authors: Timmerman Ashley , Mohanty Swomitra K. , Carlson Krista
Published: February 2020

The electrochemical detection of several pharmaceuticals and personal care products (PPCPs) in water was performed using titanium dioxide nanotube-based (Ti-NT) arrays. Sensing was performed with various pharmaceuticals in water from natural sources, achieving ppb detection limits. Low bias voltages (-1.2 V to +1.2 V) were selected for operation and correlates to sensor performance. Bias voltage was determined by cyclic voltammetry in order to record maximum oxidation and reduction peaks for the specific metal and chemical of interest. The Ti-NT arrays were decorated with various metal nanoparticles to increase the specificity and sensitivity of the sensor. Metals were chosen based on Density Functional Theory methods to calculate which metals are most likely to bind with the chemical of interest. For example, Ti-NTs functionalized with zinc nanoparticles were able to detect ppb levels of ibuprofen, while no detection occurred with the blank Ti-NTs.

Figure 1
The Benefit of an Integrative, Multiscale (Molecular- to Meso-Scale) Perspective for the Investigation of Energy Storage Materials
Authors: Marschilok Amy C , Takeuchi Kenneth J , Takeuchi Esther S
Published: February 2020

Overcoming the difference between the usable output of any energy storage systems and its theoretical energy content remains a critical challenge. The inefficiency typically results in the production of waste heat (q) rather than useful work (w). Minimization of inefficiency can be approached through optimization at the macro level, where bulk parameters are identified and varied. One approach to analyze multivariate systems is through optimization, often involving statistical methods such as design of experiments. This is an effective tool when the needed information regarding the parameters affecting the system is known. However, the diversity and intricacies of new and modified battery materials inherently reduce the probability of optimization experiments resulting in marketable products because the detailed operation mechanisms are unknown. Further, optimization will likely not yield insight into the complexities of electric energy storage systems, especially when considering any heterogeneity of ion and electron flux at the numerous interfaces over several scale lengths within a battery. This would require multiple characterization approaches used in concert, to assemble information gathered at the local or atomic level and link it to mesoscale characterization and finally system level performance. Thus, the ability to control and ultimately predict the behavior of complex systems demands not just parameterization at the bulk scale, but rather specific experimentation and understanding over multiple length scales within the same battery system, from the molecular- to the meso-scale through understanding the associated basic science. This presentation will examine insights and implications from multiscale investigations of energy storage related materials.
A Sulfide Solid Electrolyte Surface Layer Formed Via Electrolyte Additives Enables Stable Plating of Li Metal
Authors: Pang Quan , Nazar Linda F
Published: February 2020

Li metal batteries promise the next-generation rechargeable batteries for electric vehicles applications due to the highest specific capacity (3840 mA h g-1) and lowest reduction potential (−3.04 V vs. S.H.E.) of Li among all alkali and alkaline earth metals. However, a non-uniform solid electrolyte interphase (SEI) layer formed via parasite reactions of Li with the electrolytes leads to locally site-specific Li deposition, i.e., dendritic plating.1 Dynamic breaking and forming of this layer, in turn, leads to the accumulative loss of Li, build-up of the SEI and consumption of the electrolyte causing cell failure. Upon prolonged cycling, penetration of dendrites through the separator causes hazardous cell short-circuits. Modified electrolytes including concentrated electrolytes,2 LiF additive3 and artificial SEI layer4 have shown promise in suppressing dendrites.

In this presentation, we will demonstrate an in-vivo formed sulfide-based ionic conductive layer — realized by using a low concentration complexed electrolyte additive — that not only generates a kinetically favorable interface, but also reduces the corrosive reactions of the electrolyte with Li. Upon Li plating, the high ionic conductivity of the solid electrolyte layer allows the Li+flux to be evenly distributed over the conductive surface. Furthermore, even at extremely high current densities when incipient dendritic Li start to form, the reservoir additives in the electrolyte facilitate local formation of the conductive layer.

Upon resting at OCV, the Li|Li symmetric cell in the presence of the electrolyte additive shows much lower interfacial charge transfer resistance than a cell with a “blank” electrolyte (20 vs. 320 Ω cm-2). Furthermore, the impedance is stable over 2 days of rest, in contrast with significantly increasing impedance exhibited by the blank cell. Greatly improved long-term cycling of the symmetric cells is observed. The cell with additive exhibits extremely stable voltage evolution over 400 hours, whereas the blank electrolyte cell experiences voltage fluctuation followed by short-circuit after 270 hours (Figure 1a). Notably, stable cycling of Li|Li symmetric cells over 2500 hours at 1 mA cm-2 with 1 mA h cm-2 capacity was achieved using 100 mM additive (Figure 1b), and a significant decrease in polymerized solvent is observed compared to a cell with no additive. In a full Li metal cell using Li4Ti5O12 as the positive electrode, the cell with the electrolyte additive exhibits very stable capacity retention (88%) over 400 cycles. Reference

1. Y. S. Cohen, Y. Cohen, D. Aurbach, J. Phys. Chem. B, 2000, 104, 12282-12291.

2. J. Qian, W. A. Henderson, W. Xu, P. Bhattacharya, M. Engelhard, O. Borodin, J.-G. Zhang, Nat. Commun., 2015, 6, 6362.

3. Y. Lu, Z. Tu, L. A. Archer, Nat. Mater., 2014, 13, 961–969.

4. G. Zheng, S. W. Lee, Z. Liang, H.-W. Lee, K. Yan, H. Yao, H. Wang, W. Li, S. Chu, Y. Cui, Nat. Nanotech., 2014, 9, 618–623.

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Electrochemical Studies of Ru+4O2 Reactions with Lithium at Low Voltages
Authors: Yang Yiqun , Williams Jere A. , Arnold Corey L , Douglas Lacey D , Meda Lamartine
Published: February 2020

Nanostructured pyramidal shape ruthenium oxide (Ru+4O2) was studied electrochemically using cyclic voltammetry (CV) and cyclic charge-discharge (CCD) experiments. The experiments were performed at five different cut-off voltages (4.0 to 1.5, 1.0, 0.80, 0.4, and 0.1 V) versus Li/Li+. CCD experiments performed from 4.0 to 1.5 V and 4.0 to 1.0 V showed a plateau at approximately 2.1 V that corresponds to 100 and 350 mAh g-1, respectively, with no significant formation of solid electrolyte interface (SEI). Insertion and de-insertion of lithium ions in the crystalline lattice of Ru+4O2 were determined to be the dominant mechanism. CV experiments performed in the same voltage range showed a reduction and an oxidation peak at 2.1 and 2.5 V, respectively, that corroborated the CCD experiments. When the cut off voltage was set below 0.80 V, the CV showed two peak currents at ~1.0 V (Ru0/Li2O) and ~0.6 V (SEI) during the first forward potential sweep. The SEI disappeared during the second cycle and beyond. On the other hand, during the reverse potential sweep two peak currents are observed at ~1.2 V and ~2.7 V. The latter represents the oxidation of Ru0 to Ru+4 and the peak at 1.2 V is assigned to the decomposition of the SEI. The CCD experiment revealed a total capacity of approximately 1200 mAh g-1 (~6 Li+ per mol of Ru+4O2), which was determined in the voltage range from 4.0 to 0.1 V. However, the expected capacity is 806 mAh g-1 (4 Li+ per mol of Ru+4O2) as described by the conversion reaction of lithium with Ru+4O2 (Ru+4O2 + 4Li++4e- <--->Ru0 + 2Li2O). Therefore, there is an excess capacity of ~600 mAh g-1. To understand the source of the excess capacity, CCD experiments were performed in the range of 2.0 to 0.1 V vs. Li/Li+ which revealed that the material is behaving as a capacitor. CV experiments performed in the same voltage range supported the CCD experiments. The calculated storage capacity in this range is only 90 mAh g-1. This value is too small to explain the amount of excess capacity observed in this material. The most possible scenario for the excess capacity is pseudo-capacitive and interfacial storage.
Fe2C Nanocrystals Encapsulated in an Active Amorphous Carbon Matrix As High Performance Electrodes for Lithium-Ion Batteries
Authors: Che Haiying , Zhang Weimin , He Yushi , Ma Zi-Feng
Published: February 2020

A Fe2C nanocrystals encapsulated into a nitrogen and sulfur dual doped carbon matrix (Fe2C@C) was first synthesized by a simultaneous polymerization-precipitation technique followed with a high temperature pyrolysis process. This method can lead to an effective and homogenous distribution of core/shell Fe2C nanoparticles into the carbon matrix. The optimized material was applied as an anode for a lithium-ion battery, which showed a high capacity, excellent rate performance, and good cycling capability. It delivered a high specific capacity of 657.7 mA h g-1 at a current density of 0.2 A g-1, and even at a very high current density at 6 A g-1, the electrode still retained a very high specific capacity of 509.1 mA h g-1. After 150 cycles of charge/discharge at a current density of 1 A g-1, no capacity decay was observed which presents itself a promising high performance anode for LIBs. Also, the presence of Fe2C can greatly stabilize the structure of the electrode and the electrode process for the lithiation/delithiation of LIBs.

Figure 1
xLi2MnO3-yLiMn2O4-(1-x-y)LiNi0.5Mn0.5O2 for Lithium Ion Batteries
Authors: LopezdeVictoria Monica , Nieto Ramos Santander M , Torres Castro Loraine , Dorvilien Valerio , Katiyar Rajesh K. , Tripathi Balram , Morell Gerardo , Katiyar Ram S
Published: February 2020

Lithium-ion batteries are considered as an important power source for electric and hybrid electric vehicles. Li2MnO3 based composite cathode materials are one of the most investigated cathode materials due to their ability to provide high discharge capacity and excellent rate capability. In this study, we have focused on synthesizing a lithium intercalated cobalt-free layered-layered-spinel composite cathode material xLi2MnO3-yLiMn2O4-(1-x-y) LiNi0.5Mn0.5O2 (LLNMO) by solvothermal synthesis technique. The structure of the compositions was characterized using X-ray Diffraction (XRD) and Raman Spectroscopy; peaks corresponding to layered and spinel structures were identified by both study methods. The surface morphology was studied by Scanning Electron Microscope (SEM). SEM images showed agglomerations of the nano-sized particles as well as the presence of the corresponding transition metals in the compositions which was confirmed with Electron Disperse Spectroscopy (EDS). The electrochemical performance was performed on coin cells, assembled in the Ar- filled glove box; we used Li as counter electrode, spread material as cathode and Celgard as separator. LiPF6 with EC:DMC in the 1:2 ratio was used as the electrolyte. Cyclic voltammogram (CV) was performed using a scan rate of 0.1 mV/s in a voltage range from 2.0-4.8 V. The charge discharge studies were performed using a current density of 10mA/g in the same voltage range. Finally, the Electrochemical Impedance Spectroscopy (EIS) was studied between cycles to understand the effect of cycling in the charge transfer resistance and also the internal resistance of the cells. The CV, charge discharge and EIS studies revealed that the lithium intercalated cathode material developed is a promising, structurally stable material for high energy and high power density applications.
Properties of Lithium Phosphorus Oxynitride Films Prepared By Metalorganic Chemical Vapor Deposition Method
Authors: Fujibayashi Takashi , Iwabuchi Katsuhiko , Yoshii Naoki
Published: February 2020

3D-structured thin-film batteries draw attention to applications like IoT, wearable, and medical devices because of their having non-flammability, electrochemical stability, and flexibility; furthermore, their capacity density can be enhanced by designing the structure, e.g. the aspect ratio (AR) of trench and pillar structures. For realizing 3D-structured batteries with high-capacity density, the step coverage for high AR-patterned structures is a crucial process parameter. In the case of conventional physical vapor deposition (PVD) method, the coverage is not conformal enough to deposit onto a high AR-patterned surface. On the other hand, chemical vapor deposition (CVD) method is attractive to deposit much more conformal films than PVD. In this study, properties of lithium phosphorus oxynitride (LiPON), which is a promising thin-film electrolyte material due to high-chemical stability and nontoxicity, films deposited using metalorganic (MO) CVD are investigated in detail. In this experiment, utilized precursors were lithium tert-butoxide, tris(dimethylamino)phosphine, O2, and NH3. Chemical composition and microstructure of prepared films were evaluated by various analytical methods such as XPS, RBS/NRA, Raman spectroscopy, and XRD. In addition, electrochemical properties of the film were evaluated by AC impedance (Nyquist plot) and cyclic voltammetry methods. Using this MOCVD system, Li4.1PO4.2N0.7 film with 7.5 nm of crystallite size and 5.0 nm/min of deposition rate shows 5.9x10-6 S/cm at 200 nm and 3.3x10-6 S/cm at 50 nm of ionic conductivity, and an excellent step coverage on a patterned substrate is also shown by SEM and EDX (Fig. 1). These results demonstrate the LiPON film deposited by MOCVD would be successfully available for 3D-structured thin-film batteries.

Figure 1