Nanostructured surfaces for analysis of anticancer drug and cell diagnosis based on electrochemical and SERS tools

NASA Astrophysics Data System (ADS)

El-Said, Waleed A.; Yoon, Jinho; Choi, Jeong-Woo

2018-04-01

Discovering new anticancer drugs and screening their efficacy requires a huge amount of resources and time-consuming processes. The development of fast, sensitive, and nondestructive methods for the in vitro and in vivo detection of anticancer drugs' effects and action mechanisms have been done to reduce the time and resources required to discover new anticancer drugs. For the in vitro and in vivo detection of the efficiency, distribution, and action mechanism of anticancer drugs, the applications of electrochemical techniques such as electrochemical cell chips and optical techniques such as surface-enhanced Raman spectroscopy (SERS) have been developed based on the nanostructured surface. Research focused on electrochemical cell chips and the SERS technique have been reviewed here; electrochemical cell chips based on nanostructured surfaces have been developed for the in vitro detection of cell viability and the evaluation of the effects of anticancer drugs, which showed the high capability to evaluate the cytotoxic effects of several chemicals at low concentrations. SERS technique based on the nanostructured surface have been used as label-free, simple, and nondestructive techniques for the in vitro and in vivo monitoring of the distribution, mechanism, and metabolism of different anticancer drugs at the cellular level. The use of electrochemical cell chips and the SERS technique based on the nanostructured surface should be good tools to detect the effects and action mechanisms of anticancer drugs.

Application of electrochemical method to microfabricated region in single-crystal device of FeSe1- x Te x superconductors

NASA Astrophysics Data System (ADS)

Okada, Kazuhiro; Takagi, Tomohiro; Kobayashi, Masahiro; Ohnuma, Haruka; Noji, Takashi; Koike, Yoji; Ayukawa, Shin-ya; Kitano, Haruhisa

2018-04-01

The application of an electrochemical method to the iron-based chalcogenide superconductors has great potentials in enhancing their properties such as the superconducting transition temperature. Unfortunately, this method has been limited to polycrystalline powders or thin film samples with a large surface area. Here, we demonstrate that the electrochemical method can be usefully applied to single-crystal devices of FeSe1- x Te x superconductors by combining it with the focused ion beam (FIB) microfabrication techniques. Our results open a new route to developing the high-quality superconducting devices fabricated using layered iron-based chalcogenides, whose properties are electrochemically controlled.

Application of a Nanostructured Enzymatic Biosensor Based on Fullerene and Gold Nanoparticles to Polyphenol Detection.

PubMed

Tortolini, Cristina; Sanzò, Gabriella; Antiochia, Riccarda; Mazzei, Franco; Favero, Gabriele

2017-01-01

Electrochemical biosensors provide an attractive means of analyzing the content of a biological sample due to the direct conversion of a biological event to an electronic signal. The signal transduction and the general performance of electrochemical biosensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. We show herein a novel electrochemical biosensing platform based on the coupling of two different nanostructured materials (gold nanoparticles and fullerenols) displaying interesting electrochemical features. The use of these nanomaterials improved the electrochemical performance of the proposed biosensor.An application of the nanostructured enzyme-based biosensor has been developed for evaluating the detection of polyphenols either in buffer solution or in real wine samples.

Porous TiO2-ZrO2 thin film formed by electrochemical technique to improve the biocompatibility of titanium alloy in physiological environment

NASA Astrophysics Data System (ADS)

Benea, L.; Dănăilă, E.; Ponthiaux, P.

2017-02-01

Porous Ti and Ti alloys have received increasing research interest for bone tissue engineering, especially for dental and orthopaedic implants because they provide cell ingrowths and vascularization, improving of adhesion and osseointegration. The tribocorrosion process is encountered in orthopaedic and dentistry applications, since it is known that the implants are often exposed to simultaneous chemical/electrochemical and mechanical stresses. The purpose of this study was to carry out a systematic investigation of the tribo-electrochemical performance of porous TiO2-ZrO2 thin film formed by anodization of Ti-10Zr alloy surface in an artificial saliva solution and to compare the resulted performance with that of the untreated Ti-10Zr alloy surface in order to be applied for biomedical use. The in situ electrochemical technique used for investigation of tribo-electrochemical degradation was the open circuit potential (OCP) measurement performed before, during and after sliding tests. The results presented herein show that controlled anodic oxidation method can significantly improve the tribocorrosion and friction performances of Ti-10Zr alloy surface intended for biomedical applications.

A biofilm microreactor system for simultaneous electrochemical and nuclear magnetic resonance techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renslow, Ryan S.; Babauta, Jerome T.; Majors, Paul D.

2014-03-01

In order to fully understand electrochemically active biofilms and the limitations to their scale-up in industrial biofilm reactors, a complete picture of the microenvironments inside the biofilm is needed. Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for non-invasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live electrochemically active biofilms. Here, we introduce a novel biofilm microreactor system that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactorsmore » were designed with custom radiofrequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system, we grew Geobacter sulfurreducens biofilms. NMR was used to investigate growth media flow velocities, which were compared to simulated laminar flow, and electron donor concentrations inside the biofilms. We use Monte Carlo error analysis to estimate standard deviations of the electron donor concentration measurements within the biofilm. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms.« less

Binder free MnO2/PIn electrode material for supercapacitor application

NASA Astrophysics Data System (ADS)

Purty, B.; Choudhary, R. B.; Kandulna, R.; Singh, R.

2018-05-01

Electrochemically stable MnO2/PIn nanocomposite was synthesized via in-situ chemical oxidative polymerization process. The structural and morphological properties were studied through FTIR and FESEM characterizing techniques. Sphere like PIn and MnO2 nanorods offers interacting surface for charge transfer action. The electrochemical properties were investigated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopic (EIS) techniques. The significant enhancement in capacitance value with 95% coulombic efficiency and relatively low equivalent series resistance (ESR)˜0.4 Ω proved that MnO2/PIn nanocomposite is an excellent performer as an electrode material in the spectrum of supercapcitors and optoelectronic devices.

Multifunctional scanning ion conductance microscopy

PubMed Central

Page, Ashley; Unwin, Patrick R.

2017-01-01

Scanning ion conductance microscopy (SICM) is a nanopipette-based technique that has traditionally been used to image topography or to deliver species to an interface, particularly in a biological setting. This article highlights the recent blossoming of SICM into a technique with a much greater diversity of applications and capability that can be used either standalone, with advanced control (potential–time) functions, or in tandem with other methods. SICM can be used to elucidate functional information about interfaces, such as surface charge density or electrochemical activity (ion fluxes). Using a multi-barrel probe format, SICM-related techniques can be employed to deposit nanoscale three-dimensional structures and further functionality is realized when SICM is combined with scanning electrochemical microscopy (SECM), with simultaneous measurements from a single probe opening up considerable prospects for multifunctional imaging. SICM studies are greatly enhanced by finite-element method modelling for quantitative treatment of issues such as resolution, surface charge and (tip) geometry effects. SICM is particularly applicable to the study of living systems, notably single cells, although applications extend to materials characterization and to new methods of printing and nanofabrication. A more thorough understanding of the electrochemical principles and properties of SICM provides a foundation for significant applications of SICM in electrochemistry and interfacial science. PMID:28484332

3D printed stretchable capacitive sensors for highly sensitive tactile and electrochemical sensing

NASA Astrophysics Data System (ADS)

Li, Kai; Wei, Hong; Liu, Wenguang; Meng, Hong; Zhang, Peixin; Yan, Chaoyi

2018-05-01

Developments of innovative strategies for the fabrication of stretchable sensors are of crucial importance for their applications in wearable electronic systems. In this work, we report the successful fabrication of stretchable capacitive sensors using a novel 3D printing method for highly sensitive tactile and electrochemical sensing applications. Unlike conventional lithographic or templated methods, the programmable 3D printing technique can fabricate complex device structures in a cost-effective and facile manner. We designed and fabricated stretchable capacitive sensors with interdigital and double-vortex designs and demonstrated their successful applications as tactile and electrochemical sensors. Especially, our stretchable sensors exhibited a detection limit as low as 1 × 10-6 M for NaCl aqueous solution, which could have significant potential applications when integrated in electronics skins.

3D printed stretchable capacitive sensors for highly sensitive tactile and electrochemical sensing.

PubMed

Li, Kai; Wei, Hong; Liu, Wenguang; Meng, Hong; Zhang, Peixin; Yan, Chaoyi

2018-05-04

Developments of innovative strategies for the fabrication of stretchable sensors are of crucial importance for their applications in wearable electronic systems. In this work, we report the successful fabrication of stretchable capacitive sensors using a novel 3D printing method for highly sensitive tactile and electrochemical sensing applications. Unlike conventional lithographic or templated methods, the programmable 3D printing technique can fabricate complex device structures in a cost-effective and facile manner. We designed and fabricated stretchable capacitive sensors with interdigital and double-vortex designs and demonstrated their successful applications as tactile and electrochemical sensors. Especially, our stretchable sensors exhibited a detection limit as low as 1 × 10 -6 M for NaCl aqueous solution, which could have significant potential applications when integrated in electronics skins.

Ion-conducting ceramic apparatus, method, fabrication, and applications

DOEpatents

Yates, Matthew [Penfield, NY; Liu, Dongxia [Rochester, NY

2012-03-06

A c-axis-oriented HAP thin film synthesized by seeded growth on a palladium hydrogen membrane substrate. An exemplary synthetic process includes electrochemical seeding on the substrate, and secondary and tertiary hydrothermal treatments under conditions that favor growth along c-axes and a-axes in sequence. By adjusting corresponding synthetic conditions, an HAP this film can be grown to a controllable thickness with a dense coverage on the underlying substrate. The thin films have relatively high proton conductivity under hydrogen atmosphere and high temperature conditions. The c-axis oriented films may be integrated into fuel cells for application in the intermediate temperature range of 200-600.degree. C. The electrochemical-hydrothermal deposition technique may be applied to create other oriented crystal materials having optimized properties, useful for separations and catalysis as well as electronic and electrochemical applications, electrochemical membrane reactors, and in chemical sensors.

Methods for understanding microbial community structures and functions in microbial fuel cells: a review.

PubMed

Zhi, Wei; Ge, Zheng; He, Zhen; Zhang, Husen

2014-11-01

Microbial fuel cells (MFCs) employ microorganisms to recover electric energy from organic matter. However, fundamental knowledge of electrochemically active bacteria is still required to maximize MFCs power output for practical applications. This review presents microbiological and electrochemical techniques to help researchers choose the appropriate methods for the MFCs study. Pre-genomic and genomic techniques such as 16S rRNA based phylogeny and metagenomics have provided important information in the structure and genetic potential of electrode-colonizing microbial communities. Post-genomic techniques such as metatranscriptomics allow functional characterizations of electrode biofilm communities by quantifying gene expression levels. Isotope-assisted phylogenetic analysis can further link taxonomic information to microbial metabolisms. A combination of electrochemical, phylogenetic, metagenomic, and post-metagenomic techniques offers opportunities to a better understanding of the extracellular electron transfer process, which in turn can lead to process optimization for power output. Copyright © 2014 Elsevier Ltd. All rights reserved.

Scanning electrochemical microscopy (SECM) as a tool in biosensor research.

PubMed

Stoica, Leonard; Neugebauer, Sebastian; Schuhmann, Wolfgang

2008-01-01

Scanning electrochemical microscopy (SECM) is discussed as a versatile tool to provide localized (electro)chemical information in the context of biosensor research. Advantages of localized electrochemical measurements will be discussed and a brief introduction to SECM and its operation modes will be given. Experimental challenges of the different detection modes of SECM and its applicability for different fields in biosensor research are discussed. Among these are the evaluation of immobilization techniques by probing the local distribution of biological activity, the visualization of diffusion profiles of reactants, cofactors, mediators, and products, and the elucidation of (local) kinetic parameters. The combination of SECM with other scanning-probe techniques allows to maximize the information on a given biosensing system. The potential of SECM as a tool in micro-fabrication aiming for the fabrication of microstructured biosensors will be shortly discussed.

Application of electrochemical impedance spectroscopy: A phase behavior study of babassu biodiesel-based microemulsions.

PubMed

Pereira, Thulio C; Conceição, Carlos A F; Khan, Alamgir; Fernandes, Raquel M T; Ferreira, Maira S; Marques, Edmar P; Marques, Aldaléa L B

2016-11-05

Microemulsions are thermodynamically stable systems of two immiscible liquids, one aqueous and the other of organic nature, with a surfactant and/or co-surfactant adsorbed in the interface between the two phases. Biodiesel-based microemulsions, consisting of alkyl esters of fatty acids, open a new means of analysis for the application of electroanalytical techniques, and is advantageous as it eliminates the required pre-treatment of a sample. In this work, the phase behaviours of biodiesel-based microemulsions were investigated through the electrochemical impedance spectroscopy (EIS) technique. We observed thatan increase in the amount of biodiesel in the microemulsion formulation increases the resistance to charge transfer at the interface. Also, the electrical conductivity measurements revealed that a decrease or increase in electrical properties depends on the amount of biodiesel. EIS studies of the biodiesel-based microemulsion samples showed the presence of two capacitive arcs: one high-frequency and the other low-frequency. Thus, the formulation of microemulsions plays an important role in estimating the electrical properties through the electrochemical impedance spectroscopy technique. Copyright © 2016 Elsevier B.V. All rights reserved.

Studies on activated carbon derived from neem (azadirachta indica) bio-waste, and its application as supercapacitor electrode

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Parvaz, M.; Johari, Rahul; Rafat, M.

2018-04-01

The present study reports the preparation of quasi solid-state supercapacitor employing activated carbon (AC) electrodes and gel polymer electrolyte (GPE). AC was derived from Neem leaves by means of chemical activation using zinc chloride as activating agent. GPE was prepared using solution-cast technique and comprises of LiClO 4 salt, dispersed in EC:PC (1:1 vol.) and entrapped in PVdF-HFP solution. Extensive physical and electrochemical characterization of synthesized AC and GPE was done. AC was characterized using the techniques of SEM, TEM, XRD, Raman spectroscopy, TGA and BET tests while GPE was characterized by electrochemical stability window (ESW) and conductivity test. The fabricated supercapacitor cell was tested using standard electrochemical characterization techniques. It was found that the fabricated cell offers high values of specific capacitance (74.41 F g‑1), specific energy (10.33 Wh kg‑1) and specific power (4.66 kW kg‑1). These results demonstrate the suitability of prepared AC as promising electrode material for supercapacitor applications.

Application of electrochemical impedance spectroscopy: A phase behavior study of babassu biodiesel-based microemulsions

NASA Astrophysics Data System (ADS)

Pereira, Thulio C.; Conceição, Carlos A. F.; Khan, Alamgir; Fernandes, Raquel M. T.; Ferreira, Maira S.; Marques, Edmar P.; Marques, Aldaléa L. B.

2016-11-01

Microemulsions are thermodynamically stable systems of two immiscible liquids, one aqueous and the other of organic nature, with a surfactant and/or co-surfactant adsorbed in the interface between the two phases. Biodiesel-based microemulsions, consisting of alkyl esters of fatty acids, open a new means of analysis for the application of electroanalytical techniques, and is advantageous as it eliminates the required pre-treatment of a sample. In this work, the phase behaviours of biodiesel-based microemulsions were investigated through the electrochemical impedance spectroscopy (EIS) technique. We observed thatan increase in the amount of biodiesel in the microemulsion formulation increases the resistance to charge transfer at the interface. Also, the electrical conductivity measurements revealed that a decrease or increase in electrical properties depends on the amount of biodiesel. EIS studies of the biodiesel-based microemulsion samples showed the presence of two capacitive arcs: one high-frequency and the other low-frequency. Thus, the formulation of microemulsions plays an important role in estimating the electrical properties through the electrochemical impedance spectroscopy technique.

Electrochemical characterization of pulsed layer deposited hydroxyapatite-zirconia layers on Ti-21Nb-15Ta-6Zr alloy for biomedical application

NASA Astrophysics Data System (ADS)

Izquierdo, Javier; Bolat, Georgiana; Cimpoesu, Nicanor; Trinca, Lucia Carmen; Mareci, Daniel; Souto, Ricardo Manuel

2016-11-01

A new titanium base Ti-21Nb-15Ta-6Zr alloy covered with hydroxyapatite-zirconia (HA-ZrO2) by pulsed laser deposition (PLD) technique was characterized regarding its corrosion resistance in simulated physiological Ringer's solution at 37 °C. For the sake of comparison, Ti-6Al-4V standard implant alloy, with and without hydroxyapatite-zirconia coating, was also characterized. Multiscale electrochemical analysis using both conventional averaging electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, and spatially-resolved microelectrochemical techniques (scanning electrochemical microscopy, SECM) were used to investigate the electrochemical behaviour of the materials. In addition, scanning electron microscopy evidenced that no relevant surface morphology changes occurred on the materials upon immersion in the simulated physiological solution, despite variations in their electrochemical behaviour. Although uncoated metals appear to show better performances during conventional corrosion tests, the response is still quite similar for the HA-ZrO2 coated materials while providing superior resistance towards electron transfer due to the formation of a more dense film on the surface, thus effectively behaving as a passive material. It is believed corrosion of the HA-ZrO2 coated Ti-21Nb-15Ta-6Zr alloy will have negligible effect upon biochemical and cellular events at the bone-implant interface and could facilitate osseointegration.

On-line biofilm monitoring by "BIOX" electrochemical probe.

PubMed

Mollica, A; Cristiani, P

2003-01-01

The innovative electrochemical monitoring probe (BIOX) recently developed to improve the antifouling treatments of cooling systems in industrial plants is presented. On the basis of the good results obtained from applications on marine sites, some research has been stated to validate this technique in biofilm growth and prevention of microbial corrosion in fresh and drinking waters.

Spectroelectrochemistry: The Combination of Optical and Electrochemical Techniques.

ERIC Educational Resources Information Center

Heineman, William R.

1983-01-01

Two different techniques, electrochemistry and spectroscopy, can be combined for studying the redox chemistry of inorganic, organic, and biological molecules. Several commonly used spectroelectrochemical methods and their applications are described. Includes discussions of optically transparent electrodes, optical absorption/fluorescence…

Disposable Screen Printed Electrochemical Sensors: Tools for Environmental Monitoring

PubMed Central

Hayat, Akhtar; Marty, Jean Louis

2014-01-01

Screen printing technology is a widely used technique for the fabrication of electrochemical sensors. This methodology is likely to underpin the progressive drive towards miniaturized, sensitive and portable devices, and has already established its route from “lab-to-market” for a plethora of sensors. The application of these sensors for analysis of environmental samples has been the major focus of research in this field. As a consequence, this work will focus on recent important advances in the design and fabrication of disposable screen printed sensors for the electrochemical detection of environmental contaminants. Special emphasis is given on sensor fabrication methodology, operating details and performance characteristics for environmental applications. PMID:24932865

Ion-/proton-conducting apparatus and method

DOEpatents

Yates, Matthew [Penfield, NY; Liu, Dongxia [Rochester, NY

2011-05-17

A c-axis-oriented HAP thin film synthesized by seeded growth on a palladium hydrogen membrane substrate. An exemplary synthetic process includes electrochemical seeding on the substrate, and secondary and tertiary hydrothermal treatments under conditions that favor growth along c-axes and a-axes in sequence. By adjusting corresponding synthetic conditions, an HAP this film can be grown to a controllable thickness with a dense coverage on the underlying substrate. The thin films have relatively high proton conductivity under hydrogen atmosphere and high temperature conditions. The c-axis oriented films may be integrated into fuel cells for application in the intermediate temperature range of 200-600.degree. C. The electrochemical-hydrothermal deposition technique may be applied to create other oriented crystal materials having optimized properties, useful for separations and catalysis as well as electronic and electrochemical applications, electrochemical membrane reactors, and in chemical sensors.

Electrochemical separation is an attractive strategy for development of radionuclide generators for medical applications.

PubMed

Chakravarty, Rubel; Dash, Ashutosh; Pillai, M R A

2012-07-01

Electrochemical separation techniques are not widely used in radionuclide generator technology and only a few studies have been reported [1-4]. Nevertheless, this strategy is useful when other parent-daughter separation techniques are not effective or not possible. Such situations are frequent when low specific activity (LSA) parent radionuclides are used for instance with adsorption chromatographic separations, which can result in lower concentration of the daughter radionuclide in the eluent. In addition, radiation instability of the column matrix in many cases can affect the performance of the generator when long lived parent radionuclides are used. Intricate knowledge of the chemistry involved in the electrochemical separation is crucial to develop a reproducible technology that ensures that the pure daughter radionuclide can be obtained in a reasonable time of operation. Crucial parameters to be critically optimized include the applied potential, choice of electrolyte, selection of electrodes, temperature of electrolyte bath and the time of electrolysis in order to ensure that the daughter radionuclide can be reproducibly recovered in high yields and high purity. The successful electrochemical generator technologies which have been developed and are discussed in this paper include the (90)Sr/(90)Y, (188)W/(188)Re and (99)Mo/(99m)Tc generators. Electrochemical separation not only acts as a separation technique but also is an effective concentration methodology which yields high radioactive concentrations of the daughter products. The lower consumption of reagents and minimal generation of radioactive wastes using such electrochemical techniques are compatible with 'green chemistry' principles.

Fabrication of π-type flexible thermoelectric generators using an electrochemical deposition method for thermal energy harvesting applications at room temperature

NASA Astrophysics Data System (ADS)

Trung, Nguyen Huu; Van Toan, Nguyen; Ono, Takahito

2017-12-01

Although the electrochemical deposition of thermoelectric materials is a potential method for applications such as flexible thermoelectric power generators (FTEGs), to date the use of this technique is limited. This paper demonstrates a new fabrication of self-supported π-type FTEGs using electrochemical deposition of thermoelectric materials. Two types of the devices based on Bi2Te3-Cu and Bi2Te3-Sb2Te3 have been fully completed and characterized. The Bi2Te3-Cu and Bi2Te3-Sb2Te3 devices consist of 24 pairs of thermocouples that can harvest thermal energy with output power densities of 1-4 µW cm-2 from temperature differences of approximately 2 °C-4 °C from the human body. The highly scalable and new devices demonstrated in this work open up opportunities for the applications of electrochemically deposited thermoelectric materials.

Electrochemical sensor and biosensor platforms based on advanced nanomaterials for biological and biomedical applications.

PubMed

Maduraiveeran, Govindhan; Sasidharan, Manickam; Ganesan, Vellaichamy

2018-04-30

Introduction of novel functional nanomaterials and analytical technologies signify a foremost possibility for the advance of electrochemical sensor and biosensor platforms/devices for a broad series of applications including biological, biomedical, biotechnological, clinical and medical diagnostics, environmental and health monitoring, and food industries. The design of sensitive and selective electrochemical biological sensor platforms are accomplished conceivably by offering new surface modifications, microfabrication techniques, and diverse nanomaterials with unique properties for in vivo and in vitro medical analysis via relating a sensibly planned electrode/solution interface. The advantageous attributes such as low-cost, miniaturization, energy efficient, easy fabrication, online monitoring, and the simultaneous sensing capability are the driving force towards continued growth of electrochemical biosensing platforms, which have fascinated the interdisciplinary research arenas spanning chemistry, material science, biological science, and medical industries. The electrochemical biosensor platforms have potential applications in the early-stage detection and diagnosis of disease as stout and tunable diagnostic and therapeutic systems. The key aim of this review is to emphasize the newest development in the design of sensing and biosensing platforms based on functional nanomaterials for biological and biomedical applications. High sensitivity and selectivity, fast response, and excellent durability in biological media are all critical aspects which will also be wisely addressed. Potential applications of electrochemical sensor and biosensor platforms based on advanced functional nanomaterials for neuroscience diagnostics, clinical, point-of-care diagnostics and medical industries are also concisely presented. Copyright © 2017 Elsevier B.V. All rights reserved.

Dual-Mode Electro-Optical Techniques for Biosensing Applications: A Review

PubMed Central

Johnson, Steven

2017-01-01

The monitoring of biomolecular interactions is a key requirement for the study of complex biological processes and the diagnosis of disease. Technologies that are capable of providing label-free, real-time insight into these interactions are of great value for the scientific and clinical communities. Greater understanding of biomolecular interactions alongside increased detection accuracy can be achieved using technology that can provide parallel information about multiple parameters of a single biomolecular process. For example, electro-optical techniques combine optical and electrochemical information to provide more accurate and detailed measurements that provide unique insights into molecular structure and function. Here, we present a comparison of the main methods for electro-optical biosensing, namely, electrochemical surface plasmon resonance (EC-SPR), electrochemical optical waveguide lightmode spectroscopy (EC-OWLS), and the recently reported silicon-based electrophotonic approach. The comparison considers different application spaces, such as the detection of low concentrations of biomolecules, integration, the tailoring of light-matter interaction for the understanding of biomolecular processes, and 2D imaging of biointeractions on a surface. PMID:28880211

Dual-Mode Electro-Optical Techniques for Biosensing Applications: A Review.

PubMed

Juan-Colás, José; Johnson, Steven; Krauss, Thomas F

2017-09-07

The monitoring of biomolecular interactions is a key requirement for the study of complex biological processes and the diagnosis of disease. Technologies that are capable of providing label-free, real-time insight into these interactions are of great value for the scientific and clinical communities. Greater understanding of biomolecular interactions alongside increased detection accuracy can be achieved using technology that can provide parallel information about multiple parameters of a single biomolecular process. For example, electro-optical techniques combine optical and electrochemical information to provide more accurate and detailed measurements that provide unique insights into molecular structure and function. Here, we present a comparison of the main methods for electro-optical biosensing, namely, electrochemical surface plasmon resonance (EC-SPR), electrochemical optical waveguide lightmode spectroscopy (EC-OWLS), and the recently reported silicon-based electrophotonic approach. The comparison considers different application spaces, such as the detection of low concentrations of biomolecules, integration, the tailoring of light-matter interaction for the understanding of biomolecular processes, and 2D imaging of biointeractions on a surface.

Electrochemical surface modification of titanium in dentistry.

PubMed

Kim, Kyo-Han; Ramaswamy, Narayanan

2009-01-01

Titanium and its alloys have good biocompatibility with body cells and tissues and are widely used for implant applications. However, clinical procedures place more stringent and tough requirements on the titanium surface necessitating artificial surface treatments. Among the many methods of titanium surface modification, electrochemical techniques are simple and cheap. Anodic oxidation is the anodic electrochemical technique while electrophoretic and cathodic depositions are the cathodic electrochemical techniques. By anodic oxidation it is possible to obtain desired roughness, porosity and chemical composition of the oxide. Anodic oxidation at high voltages can improve the crystallinity of the oxide. The chief advantage of this technique is doping of the coating of the bath constituents and incorporation of these elements improves the properties of the oxide. Electrophoretic deposition uses hydroxyapatite (HA) powders dispersed in a suitable solvent at a particular pH. Under these operating conditions these particles acquire positive charge and coatings are obtained on the cathodic titanium by applying an external electric field. These coatings require a post-sintering treatment to improve the coating properties. Cathodic deposition is another type of electrochemical method where HA is formed in situ from an electrolyte containing calcium and phosphate ions. It is also possible to alter structure and/or chemistry of the obtained deposit. Nano-grained HA has higher surface energy and greater biological activity and therefore emphasis is being laid to produce these coatings by cathodic deposition.

Effects of pH on the electrochemical behaviour of titanium alloys for implant applications.

PubMed

Souza, Maria E P; Lima, Lonetá; Lima, Carmo R P; Zavaglia, Cecília A C; Freire, Célia M A

2009-02-01

The electrochemical behaviour of two commercial titanium alloys Ti-6Al-4 V (ASTM F136) and Ti-13Nb-13Zr (ASTM F1713) was investigated in Ringer physiological solution at two pH values (5.5 and 7.0). The corrosion properties were examined by using electrochemical techniques: Potentiodynamic anodic polarization, cyclic polarization and electrochemical impedance spectroscopy (EIS). The electrochemical corrosion properties of both alloys at different conditions were measured in terms of corrosion potential (E (corr)), corrosion current density (i (corr)) and passivation current density (i (pass)). Equivalent electrical circuits were used to modulate EIS data, in order to characterize alloys surface and better understanding the pH effect on the interface alloy/solution.

Disease-Related Detection with Electrochemical Biosensors: A Review.

PubMed

Huang, Ying; Xu, Jin; Liu, Junjie; Wang, Xiangyang; Chen, Bin

2017-10-17

Rapid diagnosis of diseases at their initial stage is critical for effective clinical outcomes and promotes general public health. Classical in vitro diagnostics require centralized laboratories, tedious work and large, expensive devices. In recent years, numerous electrochemical biosensors have been developed and proposed for detection of various diseases based on specific biomarkers taking advantage of their features, including sensitivity, selectivity, low cost and rapid response. This article reviews research trends in disease-related detection with electrochemical biosensors. Focus has been placed on the immobilization mechanism of electrochemical biosensors, and the techniques and materials used for the fabrication of biosensors are introduced in details. Various biomolecules used for different diseases have been listed. Besides, the advances and challenges of using electrochemical biosensors for disease-related applications are discussed.

Chronocoulometry: A Convenient, Rapid and Reliable Technique for Detection and Determination of Adsorbed Reactants.

ERIC Educational Resources Information Center

Anson, Fred C.; Osteryoung, Robert A.

1983-01-01

Measurement of the time dependence of the flow of charge constitutes the procedure known as chronocoulometry. Although the technique is useful in a variety of electrochemical measurements, the discussion focuses on the evaluation of reactant adsorption, the application for which the technique was originally devised. (JN)

Internal corrosion monitoring of subsea oil and gas production equipment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joosten, M.W.; Fischer, K.P.; Strommen, R.

1995-04-01

Nonintrusive techniques will dominate subsea corrosion monitoring compared with the intrusive methods because such methods do not interfere with pipeline operations. The long-term reliability of the nonintrusive techniques in general is considered to be much better than that of intrusive-type probes. The nonintrusive techniques based on radioactive tracers (TLA, NA) and FSM and UT are expected to be the main types of subsea corrosion monitoring equipment in the coming years. Available techniques that could be developed specifically for subsea applications are: electrochemical noise, corrosion potentials (using new types of reference electrodes), multiprobe system for electrochemical measurements, and video camera inspectionmore » (mini-video camera with light source). The following innovative techniques have potential but need further development: ion selective electrodes, radioactive tracers, and Raman spectroscopy.« less

Integration of electrochemistry in micro-total analysis systems for biochemical assays: recent developments.

PubMed

Xu, Xiaoli; Zhang, Song; Chen, Hui; Kong, Jilie

2009-11-15

Micro-total analysis systems (microTAS) integrate different analytical operations like sample preparation, separation and detection into a single microfabricated device. With the outstanding advantages of low cost, satisfactory analytical efficiency and flexibility in design, highly integrated and miniaturized devices from the concept of microTAS have gained widespread applications, especially in biochemical assays. Electrochemistry is shown to be quite compatible with microanalytical systems for biochemical assays, because of its attractive merits such as simplicity, rapidity, high sensitivity, reduced power consumption, and sample/reagent economy. This review presents recent developments in the integration of electrochemistry in microdevices for biochemical assays. Ingenious microelectrode design and fabrication methods, and versatility of electrochemical techniques are involved. Practical applications of such integrated microsystem in biochemical assays are focused on in situ analysis, point-of-care testing and portable devices. Electrochemical techniques are apparently suited to microsystems, since easy microfabrication of electrochemical elements and a high degree of integration with multi-analytical functions can be achieved at low cost. Such integrated microsystems will play an increasingly important role for analysis of small volume biochemical samples. Work is in progress toward new microdevice design and applications.

Studies of Aqueous and Non-Aqueous Electrochemical Interface for Applications in Microelectronic and Energy Storage Systems

NASA Astrophysics Data System (ADS)

Zheng, Jianping

Various electrochemical techniques were utilized to study a wide range of electrochemical systems in this dissertation. Mainly they are grouped in three sections: 1) the conventional metal-aqueous systems for new applications in modern microelectronic devices, 2) unconventional ceramic-organic systems for applications in Li-ion batteries and 3) novel systems composed of ionic liquids and carbon series electrodes. The objects are to probe the electrochemical/chemical reactions and interfacial structures, which are the common features of the aforementioned systems. This dissertation mainly focuses on experimental aspects, however, some theories and new models used to elucidate the experiment data have also been developed and presented. Some new experimental techniques have been explored and their limitations and validity have also been discussed. Oxalic acid (OA)-based nonalkaline solutions with H2O 2 are found to support chemically mediated removal of Ta-oxide surface films on Ta. The associated surface reactions are critical for chemical mechanical planarization (CMP) of Ta barrier. In chapter 4, a Ta coupon electrode is used as a model system in abrasive-free solutions of OA and H2O 2, where the chemical component of CMP is selectively examined. In chapter 5, electrochemical impedance spectroscopy (EIS) is employed to study the competitive reactions of surface corrosion and passivating film formation on a Cu-rotating disc electrode (RDE) in pH-adjusted solutions of H2O2, acetic acid (HAc) and ammonium dodecyl sulfate (ADS). Micrometric LiMn2O4 particles are mechano-chemically modified by ball-milling to obtain a mixture of nano- and micro-scale particles. In chapter 6, this mixture is tested as a potential active cathode material for rapid-charge Li ion batteries, and also as a model system for studying the detailed kinetics of Li intercalation/de-intercalation in such electrodes. In chapter 7, cyclic voltammetry (CV) and EIS are compared as techniques for analyzing double layer capacitances of ionic liquids (ILs) at the surfaces of two carbon-based electrodes. These systems are relevant for energy storage supercapacitors and often are associated with unconventional electrochemical properties. In chapter 8, the electrochemical interfaces of a glassy carbon (GC) and a carbon nanotube (CNT) paper electrode have been studied in EmimBF 4 and BmimBF4 ILs using CV and EIS.

Application of Desalination with CFRP Composite Electrode to Concrete Deteriorated by Chloride Attack

NASA Astrophysics Data System (ADS)

Yamaguchi, Keisuke; Ueda, Takao; Nanasawa, Akira

As a new rehabilitation technique for recovery both of loading ability and durability of concrete structures deteriorated by chloride attack, desalination (electrochemical chloride removal technique from concrete) using CFRP composite electrode bonding to concrete has been developed. In this study, basic application was tried using small RC specimens, and also application to the large-scale RC beams deteriorated by the chloride attack through the long-term exposure in the outdoors was investigated. As the result of bending test of treated specimens, the decrease of strengthening effect with the electrochemical treatment was observed in the case of small specimens using low absorption rate resin for bonding, on the other hand, in the case of large-scale RC beam using 20% absorption rate resin for bonding CFRP composite electrode, enough strengthening effect was obtained by the bending failure of RC beam with the fracture of CFRP board.

Disease-Related Detection with Electrochemical Biosensors: A Review

PubMed Central

Huang, Ying; Xu, Jin; Liu, Junjie; Wang, Xiangyang; Chen, Bin

2017-01-01

Rapid diagnosis of diseases at their initial stage is critical for effective clinical outcomes and promotes general public health. Classical in vitro diagnostics require centralized laboratories, tedious work and large, expensive devices. In recent years, numerous electrochemical biosensors have been developed and proposed for detection of various diseases based on specific biomarkers taking advantage of their features, including sensitivity, selectivity, low cost and rapid response. This article reviews research trends in disease-related detection with electrochemical biosensors. Focus has been placed on the immobilization mechanism of electrochemical biosensors, and the techniques and materials used for the fabrication of biosensors are introduced in details. Various biomolecules used for different diseases have been listed. Besides, the advances and challenges of using electrochemical biosensors for disease-related applications are discussed. PMID:29039742

Nitric oxide selective electrodes.

PubMed

Davies, Ian R; Zhang, Xueji

2008-01-01

Since nitric oxide (NO) was identified as the endothelial-derived relaxing factor in the late 1980s, many approaches have attempted to provide an adequate means for measuring physiological levels of NO. Although several techniques have been successful in achieving this aim, the electrochemical method has proved the only technique that can reliably measure physiological levels of NO in vitro, in vivo, and in real time. We describe here the development of electrochemical sensors for NO, including the fabrication of sensors, the detection principle, calibration, detection limits, selectivity, and response time. Furthermore, we look at the many experimental applications where NO selective electrodes have been successfully used.

High-Density Droplet Microarray of Individually Addressable Electrochemical Cells.

PubMed

Zhang, Huijie; Oellers, Tobias; Feng, Wenqian; Abdulazim, Tarik; Saw, En Ning; Ludwig, Alfred; Levkin, Pavel A; Plumeré, Nicolas

2017-06-06

Microarray technology has shown great potential for various types of high-throughput screening applications. The main read-out methods of most microarray platforms, however, are based on optical techniques, limiting the scope of potential applications of such powerful screening technology. Electrochemical methods possess numerous complementary advantages over optical detection methods, including its label-free nature, capability of quantitative monitoring of various reporter molecules, and the ability to not only detect but also address compositions of individual compartments. However, application of electrochemical methods for the purpose of high-throughput screening remains very limited. In this work, we develop a high-density individually addressable electrochemical droplet microarray (eDMA). The eDMA allows for the detection of redox-active reporter molecules irrespective of their electrochemical reversibility in individual nanoliter-sized droplets. Orthogonal band microelectrodes are arranged to form at their intersections an array of three-electrode systems for precise control of the applied potential, which enables direct read-out of the current related to analyte detection. The band microelectrode array is covered with a layer of permeable porous polymethacrylate functionalized with a highly hydrophobic-hydrophilic pattern, forming spatially separated nanoliter-sized droplets on top of each electrochemical cell. Electrochemical characterization of single droplets demonstrates that the underlying electrode system is accessible to redox-active molecules through the hydrophilic polymeric pattern and that the nonwettable hydrophobic boundaries can spatially separate neighboring cells effectively. The eDMA technology opens the possibility to combine the high-throughput biochemical or living cell screenings using the droplet microarray platform with the sequential electrochemical read-out of individual droplets.

All-printed magnetically self-healing electrochemical devices

PubMed Central

Bandodkar, Amay J.; López, Cristian S.; Vinu Mohan, Allibai Mohanan; Yin, Lu; Kumar, Rajan; Wang, Joseph

2016-01-01

The present work demonstrates the synthesis and application of permanent magnetic Nd2Fe14B microparticle (NMP)–loaded graphitic inks for realizing rapidly self-healing inexpensive printed electrochemical devices. The incorporation of NMPs into the printable ink imparts impressive self-healing ability to the printed conducting trace, with rapid (~50 ms) recovery of repeated large (3 mm) damages at the same or different locations without any user intervention or external trigger. The permanent and surrounding-insensitive magnetic properties of the NMPs thus result in long-lasting ability to repair extreme levels of damage, independent of ambient conditions. This remarkable self-healing capability has not been reported for existing man-made self-healing systems and offers distinct advantages over common capsule and intrinsically self-healing systems. The printed system has been characterized by leveraging crystallographic, magnetic hysteresis, microscopic imaging, electrical conductivity, and electrochemical techniques. The real-life applicability of the new self-healing concept is demonstrated for the autonomous repair of all-printed batteries, electrochemical sensors, and wearable textile-based electrical circuits, indicating considerable promise for widespread practical applications and long-lasting printed electronic devices. PMID:27847875

Understanding materials challenges for rechargeable ion batteries with in situ transmission electron microscopy

NASA Astrophysics Data System (ADS)

Yuan, Yifei; Amine, Khalil; Lu, Jun; Shahbazian-Yassar, Reza

2017-08-01

An in-depth understanding of material behaviours under complex electrochemical environment is critical for the development of advanced materials for the next-generation rechargeable ion batteries. The dynamic conditions inside a working battery had not been intensively explored until the advent of various in situ characterization techniques. Real-time transmission electron microscopy of electrochemical reactions is one of the most significant breakthroughs poised to enable radical shift in our knowledge on how materials behave in the electrochemical environment. This review, therefore, summarizes the scientific discoveries enabled by in situ transmission electron microscopy, and specifically emphasizes the applicability of this technique to address the critical challenges in the rechargeable ion battery electrodes, electrolyte and their interfaces. New electrochemical systems such as lithium-oxygen, lithium-sulfur and sodium ion batteries are included, considering the rapidly increasing application of in situ transmission electron microscopy in these areas. A systematic comparison between lithium ion-based electrochemistry and sodium ion-based electrochemistry is also given in terms of their thermodynamic and kinetic differences. The effect of the electron beam on the validity of in situ observation is also covered. This review concludes by providing a renewed perspective for the future directions of in situ transmission electron microscopy in rechargeable ion batteries.

Understanding materials challenges for rechargeable ion batteries with in situ transmission electron microscopy

PubMed Central

Yuan, Yifei; Amine, Khalil; Lu, Jun; Shahbazian-Yassar, Reza

2017-01-01

An in-depth understanding of material behaviours under complex electrochemical environment is critical for the development of advanced materials for the next-generation rechargeable ion batteries. The dynamic conditions inside a working battery had not been intensively explored until the advent of various in situ characterization techniques. Real-time transmission electron microscopy of electrochemical reactions is one of the most significant breakthroughs poised to enable radical shift in our knowledge on how materials behave in the electrochemical environment. This review, therefore, summarizes the scientific discoveries enabled by in situ transmission electron microscopy, and specifically emphasizes the applicability of this technique to address the critical challenges in the rechargeable ion battery electrodes, electrolyte and their interfaces. New electrochemical systems such as lithium–oxygen, lithium–sulfur and sodium ion batteries are included, considering the rapidly increasing application of in situ transmission electron microscopy in these areas. A systematic comparison between lithium ion-based electrochemistry and sodium ion-based electrochemistry is also given in terms of their thermodynamic and kinetic differences. The effect of the electron beam on the validity of in situ observation is also covered. This review concludes by providing a renewed perspective for the future directions of in situ transmission electron microscopy in rechargeable ion batteries.

Conducting polymer-based electrochemical biosensors for neurotransmitters: A review.

PubMed

Moon, Jong-Min; Thapliyal, Neeta; Hussain, Khalil Khadim; Goyal, Rajendra N; Shim, Yoon-Bo

2018-04-15

Neurotransmitters are important biochemical molecules that control behavioral and physiological functions in central and peripheral nervous system. Therefore, the analysis of neurotransmitters in biological samples has a great clinical and pharmaceutical importance. To date, various methods have been developed for their assay. Of the various methods, the electrochemical sensors demonstrated the potential of being robust, selective, sensitive, and real time measurements. Recently, conducting polymers (CPs) and their composites have been widely employed in the fabrication of various electrochemical sensors for the determination of neurotransmitters. Hence, this review presents a brief introduction to the electrochemical biosensors, with the detailed discussion on recent trends in the development and applications of electrochemical neurotransmitter sensors based on CPs and their composites. The review covers the sensing principle of prime neurotransmitters, including glutamate, aspartate, tyrosine, epinephrine, norepinephrine, dopamine, serotonin, histamine, choline, acetylcholine, nitrogen monoxide, and hydrogen sulfide. In addition, the combination with other analytical techniques was also highlighted. Detection challenges and future prospective of the neurotransmitter sensors were discussed for the development of biomedical and healthcare applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Microfabricated Electrochemical Cell-Based Biosensors for Analysis of Living Cells In Vitro

PubMed Central

Wang, Jun; Wu, Chengxiong; Hu, Ning; Zhou, Jie; Du, Liping; Wang, Ping

2012-01-01

Cellular biochemical parameters can be used to reveal the physiological and functional information of various cells. Due to demonstrated high accuracy and non-invasiveness, electrochemical detection methods have been used for cell-based investigation. When combined with improved biosensor design and advanced measurement systems, the on-line biochemical analysis of living cells in vitro has been applied for biological mechanism study, drug screening and even environmental monitoring. In recent decades, new types of miniaturized electrochemical biosensor are emerging with the development of microfabrication technology. This review aims to give an overview of the microfabricated electrochemical cell-based biosensors, such as microelectrode arrays (MEA), the electric cell-substrate impedance sensing (ECIS) technique, and the light addressable potentiometric sensor (LAPS). The details in their working principles, measurement systems, and applications in cell monitoring are covered. Driven by the need for high throughput and multi-parameter detection proposed by biomedicine, the development trends of electrochemical cell-based biosensors are also introduced, including newly developed integrated biosensors, and the application of nanotechnology and microfluidic technology. PMID:25585708

Electrochemically formed 3D hierarchical thin films of cobalt-manganese (Co-Mn) hexacyanoferrate hybrids for electrochemical applications

NASA Astrophysics Data System (ADS)

Alam Venugopal, Narendra Kumar; Joseph, James

2016-02-01

Here we report the feasibility of forming 3D nanostructured hexacyanoferates of Cobalt and Manganese (Co-MnHCF) on GC surface by a facile electrochemical method. This 3D architecture on glassy carbon electrode characterised systematically by voltammetry and other physical characterisation techniques like Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform Infrared spectroscopy (FTIR) etc,. Electrochemical Quartz crystal microbalance (EQCM) studies helped out to calculate the total mass change during Co-MnHCF formation. Electrochemical studies reveal that the formal redox potentials of both Co and MnHCF films remained close to that of newly formed Co-MnHCF hybrid films. These 3D modified films were successfully applied for two different electrochemical applications i) For pseudocapacitor studies in KNO3 medium ii) Investigated the electrocatalytic behaviour of redox film towards water oxidation reaction in alkaline medium. Electrochemical performances of newly formed Co-MnHCF are compared with their individual transition metal (Co, Mn) hexacyanoferrates. The resulting material shows a specific capacitance of 350 F g-1 through its fast reversible redox reaction of electrochemically formed Co-MnHCF modified film. Interestingly we showed the overpotential of 450 mV (from its thermodynamic voltage 1.2 V) to attain its optimum current density of 10 mA cm-2 for O2 evolution in alkaline medium.

Numerical simulation of coupled electrochemical and transport processes in battery systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liaw, B.Y.; Gu, W.B.; Wang, C.Y.

1997-12-31

Advanced numerical modeling to simulate dynamic battery performance characteristics for several types of advanced batteries is being conducted using computational fluid dynamics (CFD) techniques. The CFD techniques provide efficient algorithms to solve a large set of highly nonlinear partial differential equations that represent the complex battery behavior governed by coupled electrochemical reactions and transport processes. The authors have recently successfully applied such techniques to model advanced lead-acid, Ni-Cd and Ni-MH cells. In this paper, the authors briefly discuss how the governing equations were numerically implemented, show some preliminary modeling results, and compare them with other modeling or experimental data reportedmore » in the literature. The authors describe the advantages and implications of using the CFD techniques and their capabilities in future battery applications.« less

Enzyme-linked electrochemical DNA ligation assay using magnetic beads.

PubMed

Stejskalová, Eva; Horáková, Petra; Vacek, Jan; Bowater, Richard P; Fojta, Miroslav

2014-07-01

DNA ligases are essential enzymes in all cells and have been proposed as targets for novel antibiotics. Efficient DNA ligase activity assays are thus required for applications in biomedical research. Here we present an enzyme-linked electrochemical assay based on two terminally tagged probes forming a nicked junction upon hybridization with a template DNA. Nicked DNA bearing a 5' biotin tag is immobilized on the surface of streptavidin-coated magnetic beads, and ligated product is detected via a 3' digoxigenin tag recognized by monoclonal antibody-alkaline phosphatase conjugate. Enzymatic conversion of napht-1-yl phosphate to napht-1-ol enables sensitive detection of the voltammetric signal on a pyrolytic graphite electrode. The technique was tested under optimal conditions and various situations limiting or precluding the ligation reaction (such as DNA substrates lacking 5'-phosphate or containing a base mismatch at the nick junction, or application of incompatible cofactor), and utilized for the analysis of the nick-joining activity of a range of recombinant Escherichia coli DNA ligase constructs. The novel technique provides a fast, versatile, specific, and sensitive electrochemical assay of DNA ligase activity.

Screen-Printed Electrodes Modified with “Green” Metals for Electrochemical Stripping Analysis of Toxic Elements

PubMed Central

Economou, Anastasios

2018-01-01

This work reviews the field of screen-printed electrodes (SPEs) modified with “green” metals for electrochemical stripping analysis of toxic elements. Electrochemical stripping analysis has been established as a useful trace analysis technique offering many advantages compared to competing optical techniques. Although mercury has been the preferred electrode material for stripping analysis, the toxicity of mercury and the associated legal requirements in its use and disposal have prompted research towards the development of “green” metals as alternative electrode materials. When combined with the screen-printing technology, such environment-friendly metals can lead to disposable sensors for trace metal analysis with excellent operational characteristics. This review focuses on SPEs modified with Au, Bi, Sb, and Sn for stripping analysis of toxic elements. Different modification approaches (electroplating, bulk modification, use of metal precursors, microengineering techniques) are considered and representative applications are described. A developing related field, namely biosensing based on stripping analysis of metallic nanoprobe labels, is also briefly mentioned. PMID:29596391

Screen-Printed Electrodes Modified with "Green" Metals for Electrochemical Stripping Analysis of Toxic Elements.

PubMed

Economou, Anastasios

2018-03-29

This work reviews the field of screen-printed electrodes (SPEs) modified with "green" metals for electrochemical stripping analysis of toxic elements. Electrochemical stripping analysis has been established as a useful trace analysis technique offering many advantages compared to competing optical techniques. Although mercury has been the preferred electrode material for stripping analysis, the toxicity of mercury and the associated legal requirements in its use and disposal have prompted research towards the development of "green" metals as alternative electrode materials. When combined with the screen-printing technology, such environment-friendly metals can lead to disposable sensors for trace metal analysis with excellent operational characteristics. This review focuses on SPEs modified with Au, Bi, Sb, and Sn for stripping analysis of toxic elements. Different modification approaches (electroplating, bulk modification, use of metal precursors, microengineering techniques) are considered and representative applications are described. A developing related field, namely biosensing based on stripping analysis of metallic nanoprobe labels, is also briefly mentioned.

A biofilm microreactor system for simultaneous electrochemical and nuclear magnetic resonance techniques.

PubMed

Renslow, R S; Babauta, J T; Majors, P D; Mehta, H S; Ewing, R J; Ewing, T W; Mueller, K T; Beyenal, H

2014-01-01

Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for noninvasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live biofilms respiring on electrodes. Here, we describe a biofilm microreactor system, including a reusable and a disposable reactor, that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactors were designed with custom radio frequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system we grew Geobacter sulfurreducens biofilms on electrodes. EC-NMR was used to investigate growth medium flow velocities and depth-resolved acetate concentration inside the biofilm. As a novel contribution we used Monte Carlo error analysis to estimate the standard deviations of the acetate concentration measurements. Overall, we found that the disposable EC-NMR microreactor provided a 9.7 times better signal-to-noise ratio over the reusable reactor. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms.

Estrone specific molecularly imprinted polymeric nanospheres: synthesis, characterization and applications for electrochemical sensor development.

PubMed

Congur, Gulsah; Senay, Hilal; Turkcan, Ceren; Canavar, Ece; Erdem, Arzum; Akgol, Sinan

2013-06-28

The aim of this study is (i) to prepare estrone-imprinted nanospheres (nano-EST-MIPs) and (ii) to integrate them into the electrochemical sensor as a recognition layer. N-methacryloyl-(l)-phenylalanine (MAPA) was chosen as the complexing monomer. Firstly, estrone (EST) was complexed with MAPA and the EST-imprinted poly(2-hyroxyethylmethacrylate-co-N-methacryloyl-(l)-phenylalanine) [EST-imprinted poly(HEMA-MAPA)] nanospheres were synthesized by surfactant- free emulsion polymerization method. The specific surface area of the EST-imprinted poly(HEMA-MAPA) nanospheres was found to be 1275 m2/g with a size of 163.2 nm in diameter. According to the elemental analysis results, the nanospheres contained 95.3 mmole MAPA/g nanosphere. The application of EST specific MIP nanospheres for the development of an electrochemical biosensor was introduced for the first time in our study by using electrochemical impedance spectroscopy (EIS) technique. This nano-MIP based sensor presented a great specificity and selectivity for EST.

A Corona Discharge Initiated Electrochemical Electrospray Ionization Technique

PubMed Central

Lloyd, John R.; Hess, Sonja

2009-01-01

We report here the development of a corona discharge (CD) initiated electrochemical (EC) electrospray ionization (ESI) technique using a standard electrospray ion source. This is a new ionization technique distinct from ESI, electrochemistry inherent to ESI, APCI, and techniques using hydroxyl radicals produced under atmospheric pressure conditions. By maximizing the observable CD at the tip of a stainless steel ESI capillary, efficient electrochemical oxidation of electrochemically active compounds is observed. For electrochemical oxidation to be observed, the ionization potential of the analyte must be lower than Fe. Ferrocene labeled compounds were chosen as the electrochemically active moiety. The electrochemical cell in the ESI source was robust and generated ions with selectivity according to the ionization potential of the analytes and up to zeptomolar sensitivity. Our results indicate that CD initiated electrochemical ionization has the potential to become a powerful technique to increase the dynamic range, sensitivity and selectivity of ESI experiments. Synopsis Using a standard ESI source a corona discharge initiated electrochemical ionization technique was established resulting from the electrochemistry occurring at the CD electrode surface. PMID:19747843

Electrochemical and nonenzymatic glucose biosensor based on MDPA/MWNT/PGE nanocomposite.

PubMed

Surucu, Ozge; Abaci, Serdar

2017-09-01

The nonenzymatic detection of glucose has been widely investigated in a variety of fields ranging from biomedical applications to ecological approaches. Among these fields, electrochemical methods have great advantages such as high electrocatalytic ability, high sensitivity, good selectivity and low-cost for the electrooxidation of glucose. Future trends on glucose sensing are nanostructured electrodes depending upon the development of nanotechnology. In this study, an electrochemical and nonenzymatic glucose sensor based on (E)-4-((5-methylthiazole-2-yl)diazenyl)-N-phenylaniline (MDPA)/multi-walled carbon nanotube (MWNT)/pencil graphite electrode (PGE) was performed. Electrochemical measurements were obtained using cyclic voltammetry and square wave voltammetry techniques, and characterization of surfaces was carried out using scanning electron microscope and electrochemical impedance spectroscopy techniques. The modification of PGE was made using MDPA and MWNT, and 10 cycles coating was used to prepare the proposed electrode. The effects of scan rate and pH on the peak potential and the peak current were determined. The limit of detection and linear range were calculated using various concentrations of glucose. The interference study was made using coexisting substances including metal ions such as Al 3+ , Cu 2+ , Fe 3+ and ascorbic acid. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochemical impedance spectroscopy investigation on the clinical lifetime of ProTaper rotary file system.

PubMed

Penta, Virgil; Pirvu, Cristian; Demetrescu, Ioana

2014-01-01

The main objective of the current paper is to show that electrochemical impedance spectroscopy (EIS) could be a method for evaluating and predicting of ProTaper rotary file system clinical lifespan. This particular aspect of everyday use of the endodontic files is of great importance in each dental practice and has profound clinical implications. The method used for quantification resides in the electrochemical impedance spectroscopy theory and has in its main focus the characteristics of the surface titanium oxide layer. This electrochemical technique has been adapted successfully to identify the quality of the Ni-Ti files oxide layer. The modification of this protective layer induces changes in corrosion behavior of the alloy modifying the impedance value of the file. In order to assess the method, 14 ProTaper sets utilized on different patients in a dental clinic have been submitted for testing using EIS. The information obtained in regard to the surface oxide layer has offered an indication of use and proves that the said layer evolves with each clinical application. The novelty of this research is related to an electrochemical technique successfully adapted for Ni-Ti file investigation and correlation with surface and clinical aspects.

ADHESION AND DE-ADHESION MECHANISMS AT POLYMER/METAL INTERFACES: Mechanistic Understanding Based on In Situ Studies of Buried Interfaces

NASA Astrophysics Data System (ADS)

Grundmeier, G.; Stratmann, M.

2005-08-01

The review highlights the state-of-the-art research regarding the application of modern in situ spectroscopic, microscopic, and electrochemical techniques to improve the understanding of the interaction of organic molecules with metal surfaces. We also consider the chemical and electrochemical processes that lead to a de-adhesion of polymers from metal surfaces. Spectroscopic techniques such as surface-enhanced infrared or Raman spectroscopy provide molecular understanding of organic molecules and water at buried metal surfaces. This information is complementary to adhesion studies by means of atomic force microscopy and de-adhesion studies of polymer layers from metals by means of a scanning Kelvin probe. Adhesion and de-adhesion mechanisms are discussed, especially those involving humid and corrosive environments, which are the predominant and most important for metal/polymer composites in engineering applications.

Hydrothermal Synthesis and Electrochemical Properties of CoS2-Reduced Graphene Oxide Nanocomposite for Supercapacitor Application

NASA Astrophysics Data System (ADS)

Venkateshalu, Sandhya; Rangappa, Dinesh; Grace, Andrews Nirmala

A Cobalt disulfide-reduced graphene oxide (CoS2-RGO) nanocomposite was prepared by a simple hydrothermal method and the prepared nanocomposite was characterized using various techniques like XRD, SEM and FTIR. The results of these techniques indicated the uniform deposition of CoS2 nanoparticles on Graphene sheets. Further, the prepared nanocomposites were tested for its activity towards energy storage and the test results showed a specific capacitance of 28F/g in an aqueous 20% KOH electrolyte at a current density of 0.5A/g. All these materials showed highly reversible charge-discharge cycles. The overall electrochemical performance of this composite is shown to be drastically improved when compared to bare CoS2 nanoparticles. Thus with the good electrochemical properties, CoS2-RGO nanocomposites could be effectively used as an electrode material for supercapacitors.

Probing electrokinetics in microchannels and nanochannels with electrochemical measurements

NASA Astrophysics Data System (ADS)

Schiffbauer, Jarrod; Park, Sinwook; Yossifon, Gilad

2013-11-01

We present a brief review of recent experimental and theoretical results concerning the use of electrochemical impedance spectroscopy (EIS), in conjunction with other electrochemical measurements (chronoamperometry, linear sweep voltammetry), to characterize the response of micro- and nanofluidic systems. Using these techniques, the interplay between conduction, diffusion, and convection are probed across a range of time- and length scales. The resulting information permits characterization of the respective roles of processes in both micro- and nanchannel regions of a fluidic device. Such techniques provide a useful probe of transient behavior at the micro-nanochannel interface, have great potential in biomolecular sensing applications, and may be useful in the study of surface properties at the fluid-solid interface. We wish to acknowledge Israel Science Foundation, grant number 2015240, the Technion Russel-Berrie Nanotechnology Institute (RBNI) and a fellowship grant from the Techion Faculty of Mechanical Engineering.

Synthesis, Characterization, and Electrochemical Properties of Polyaniline Thin Films

NASA Astrophysics Data System (ADS)

Rami, Soukaina

Conjugated polymers have been used in various applications (battery, supercapacitor, electromagnetic shielding, chemical sensor, biosensor, nanocomposite, light-emitting-diode, electrochromic display etc.) due to their excellent conductivity, electrochemical and optical properties, and low cost. Polyaniline has attracted the researchers from all disciplines of science, engineering, and industry due to its redox properties, environmental stability, conductivity, and optical properties. Moreover, it is a polymer with fast electroactive switching and reversible properties displayed at low potential, which is an important feature in many applications. The thin oriented polyaniline films have been fabricated using self-assembly, Langmuir-Blodgett, in-situ self-assembly, layer-by-layer, and electrochemical technique. The focus of this thesis is to synthesize and characterize polyaniline thin films with and without dyes. Also, the purpose of this thesis is to find the fastest electroactive switching PANI electrode in different electrolytic medium by studying their electrochemical properties. These films were fabricated using two deposition techniques: in-situ self-assembly and electrochemical deposition. The characterization of these films was done using techniques such as Fourier Transform Infrared Spectroscopy (FTIR), UV-spectroscopy, Scanning Electron Microscope (SEM), and X-Ray Diffraction (XRD). FTIR and UV-spectroscopy showed similar results in the structure of the polyaniline films. However, for the dye incorporated films, since there was an addition in the synthesis of the material, peak locations shifted, and new peaks corresponding to these materials appeared. The 1 layer PANI showed compact film morphology, comparing to other PANI films, which displayed a fiber-like structure. Finally, the electrochemical properties of these thin films were studied using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) in different scenarios. These scenarios included the study in different acid based electrolytes and different gel based electrolytes. The ultra-thin self-assembled PANI films were shown to have a faster switching time, especially for the 1 layer PANI, whereas the color contrast could be observed for the film containing the dye molecule. Also, HCl based electrolyte gave the best electrochemical reversibility compared to other acids used. For the gelatin and PVA based electrolytes, having the same concentration, the results were similar. Hence, the change in the electrolyte consistencies, from liquid to semi-solid, did not change the electrochemical properties of the films. Finally, in the EIS, it was shown that these PANI thin films exhibit a pseudo-capacitance behavior, and as the film thickness grew, the capacitance increased.

Role of carbon nanotubes in electroanalytical chemistry: a review.

PubMed

Agüí, Lourdes; Yáñez-Sedeño, Paloma; Pingarrón, José M

2008-08-01

This review covers recent advances in the development of new designs of electrochemical sensors and biosensors that make use of electrode surfaces modification with carbon nanotubes. Applications based on carbon nanotubes-driven electrocatalytic effects, and the construction and analytical usefulness of new hybrid materials with polymers or other nanomaterials will be treated. Moreover, electrochemical detection using carbon nanotubes-modified electrodes as detecting systems in separation techniques such as high performance liquid chromatography (HPLC) or capillary electrophoresis (CE) will be also considered. Finally, the preparation of electrochemical biosensors, including enzyme electrodes, immunosensors and DNA biosensors, in which carbon nanotubes play a significant role in their sensing performance will be separately considered.

Preliminary Electrochemical Characterization of Anode Supported Solid Oxide Cell (AS-SOC) Produced in the Institute of Power Engineering Operated in Electrolysis Mode (SOEC)

NASA Astrophysics Data System (ADS)

Kupecki, Jakub; Motyliński, Konrad; Skrzypkiewicz, Marek; Wierzbicki, Michał; Naumovich, Yevgeniy

2017-12-01

The article discusses the operation of solid oxide electrochemical cells (SOC) developed in the Institute of Power Engineering as prospective key components of power-to-gas systems. The fundamentals of the solid oxide cells operated as fuel cells (SOFC - solid oxide fuel cells) and electrolysers (SOEC - solid oxide fuel cells) are given. The experimental technique used for electrochemical characterization of cells is presented. The results obtained for planar cell with anodic support are given and discussed. Based on the results, the applicability of the cells in power-to-gas systems (P2G) is evaluated.

Recent Development of Advanced Electrode Materials by Atomic Layer Deposition for Electrochemical Energy Storage.

PubMed

Guan, Cao; Wang, John

2016-10-01

Electrode materials play a decisive role in almost all electrochemical energy storage devices, determining their overall performance. Proper selection, design and fabrication of electrode materials have thus been regarded as one of the most critical steps in achieving high electrochemical energy storage performance. As an advanced nanotechnology for thin films and surfaces with conformal interfacial features and well controllable deposition thickness, atomic layer deposition (ALD) has been successfully developed for deposition and surface modification of electrode materials, where there are considerable issues of interfacial and surface chemistry at atomic and nanometer scale. In addition, ALD has shown great potential in construction of novel nanostructured active materials that otherwise can be hardly obtained by other processing techniques, such as those solution-based processing and chemical vapor deposition (CVD) techniques. This review focuses on the recent development of ALD for the design and delivery of advanced electrode materials in electrochemical energy storage devices, where typical examples will be highlighted and analyzed, and the merits and challenges of ALD for applications in energy storage will also be discussed.

Recent Development of Advanced Electrode Materials by Atomic Layer Deposition for Electrochemical Energy Storage

PubMed Central

2016-01-01

Electrode materials play a decisive role in almost all electrochemical energy storage devices, determining their overall performance. Proper selection, design and fabrication of electrode materials have thus been regarded as one of the most critical steps in achieving high electrochemical energy storage performance. As an advanced nanotechnology for thin films and surfaces with conformal interfacial features and well controllable deposition thickness, atomic layer deposition (ALD) has been successfully developed for deposition and surface modification of electrode materials, where there are considerable issues of interfacial and surface chemistry at atomic and nanometer scale. In addition, ALD has shown great potential in construction of novel nanostructured active materials that otherwise can be hardly obtained by other processing techniques, such as those solution‐based processing and chemical vapor deposition (CVD) techniques. This review focuses on the recent development of ALD for the design and delivery of advanced electrode materials in electrochemical energy storage devices, where typical examples will be highlighted and analyzed, and the merits and challenges of ALD for applications in energy storage will also be discussed. PMID:27840793

Optimization of printing techniques for electrochemical biosensors

NASA Astrophysics Data System (ADS)

Zainuddin, Ahmad Anwar; Mansor, Ahmad Fairuzabadi Mohd; Rahim, Rosminazuin Ab; Nordin, Anis Nurashikin

2017-03-01

Electrochemical biosensors show great promise for point-of-care applications due to their low cost, portability and compatibility with microfluidics. The miniature size of these sensors provides advantages in terms of sensitivity, specificity and allows them to be mass produced in arrays. The most reliable fabrication technique for these sensors is lithography followed by metal deposition using sputtering or chemical vapor deposition techniques. This technique which is usually done in the cleanroom requires expensive masking followed by deposition. Recently, cheaper printing techniques such as screen-printing and ink-jet printing have become popular due to its low cost, ease of fabrication and mask-less method. In this paper, two different printing techniques namely inkjet and screen printing are demonstrated for an electrochemical biosensor. For ink-jet printing technique, optimization of key printing parameters, such as pulse voltages, drop spacing and waveform setting, in-house temperature and cure annealing for obtaining the high quality droplets, are discussed. These factors are compared with screen-printing parameters such as mesh size, emulsion thickness, minimum spacing of lines and curing times. The reliability and reproducibility of the sensors are evaluated using scotch tape test, resistivity and profile-meter measurements. It was found that inkjet printing is superior because it is mask-less, has minimum resolution of 100 µm compared to 200 µm for screen printing and higher reproducibility rate of 90% compared to 78% for screen printing.

Multimodal technique to eliminate humidity interference for specific detection of ethanol.

PubMed

Jalal, Ahmed Hasnain; Umasankar, Yogeswaran; Gonzalez, Pablo J; Alfonso, Alejandro; Bhansali, Shekhar

2017-01-15

Multimodal electrochemical technique incorporating both open circuit potential (OCP) and amperometric techniques have been conceptualized and implemented to improve the detection of specific analyte in systems where more than one analyte is present. This approach has been demonstrated through the detection of ethanol while eliminating the contribution of water in a micro fuel cell sensor system. The sensor was interfaced with LMP91000 potentiostat, controlled through MSP430F5529LP microcontroller to implement an auto-calibration algorithm tailored to improve the detection of alcohol. The sensor was designed and fabricated as a three electrode system with Nafion as a proton exchange membrane (PEM). The electrochemical signal of the interfering phase (water) was eliminated by implementing the multimodal electrochemical detection technique. The results were validated by comparing sensor and potentiostat performances with a commercial sensor and potentiostat respectively. The results suggest that such a sensing system can detect ethanol at concentrations as low as 5ppm. The structure and properties such as low detection limit, selectivity and miniaturized size enables potential application of this device in wearable transdermal alcohol measurements. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of differential pulse voltammetry to determine the efficiency of stripping tocopherols from commercial fish oil

USDA-ARS?s Scientific Manuscript database

There has been an increase in the use of electrochemical methods for monitoring antioxidant levels in a variety of disciplines due to the sensitivity, low detection limits, ease of use, low cost and rapid analysis time offered by these techniques. One technique that has received specific attention i...

Single-Atom Electrocatalysts.

PubMed

Zhu, Chengzhou; Fu, Shaofang; Shi, Qiurong; Du, Dan; Lin, Yuehe

2017-11-06

Recent years have witnessed a dramatic increase in the production of sustainable and renewable energy. However, the electrochemical performances of the various systems are limited, and there is an intensive search for highly efficient electrocatalysts by more rational control over the size, shape, composition, and structure. Of particular interest are the studies on single-atom catalysts (SACs), which have sparked new interests in electrocatalysis because of their high catalytic activity, stability, selectivity, and 100 % atom utilization. In this Review, we introduce innovative syntheses and characterization techniques for SACs, with a focus on their electrochemical applications in the oxygen reduction/evolution reaction, hydrogen evolution reaction, and hydrocarbon conversion reactions for fuel cells (electrooxidation of methanol, ethanol, and formic acid). The electrocatalytic performance is further considered at an atomic level and the underlying mechanisms are discussed. The ultimate goal is the tailoring of single atoms for electrochemical applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

New Techniques for Thermo-electrochemical Analysis of Lithium-ion Batteries for Space Applications

NASA Technical Reports Server (NTRS)

Walker, William; Ardebili, H.

2013-01-01

The overall goal of this study was achieved: Replicated the numerical assessment performed by Chen et. al. (2005). Displayed the ability of Thermal Desktop to be coupled with thermo-electrochemical analysis techniques. such that the local heat generated on the cells is a function of the model itself using logic blocks and arrays. Differences in the TD temperature vs. depth of discharge profiles and Chen's was most likely due to differences in two primary areas: Contact regions and conductance values. Differences in density and specific heat values. center dot The model results are highly dependent on the accuracy of the material properties with respect to the multiple layers of an individual cell.

Electrochemical methods for monitoring of environmental carcinogens.

PubMed

Barek, J; Cvacka, J; Muck, A; Quaiserová, V; Zima, J

2001-04-01

The use of modern electroanalytical techniques, namely differential pulse polarography, differential pulse voltammetry on hanging mercury drop electrode or carbon paste electrode, adsorptive stripping voltammetry and high performance liquid chromatography with electrochemical detection for the determination of trace amounts of carcinogenic N-nitroso compounds, azo compounds, heterocyclic compounds, nitrated polycyclic aromatic hydrocarbons and aromatic and heterocyclic amines is discussed. Scope and limitations of these methods are described and some practical applications based on their combination with liquid-liquid or solid phase extraction are given.

Electrochemical Nanoparticle Sizing Via Nano-Impacts: How Large a Nanoparticle Can be Measured?

PubMed Central

Bartlett, Thomas R; Sokolov, Stanislav V; Compton, Richard G

2015-01-01

The field of nanoparticle (NP) sizing encompasses a wide array of techniques, with electron microscopy and dynamic light scattering (DLS) having become the established methods for NP quantification; however, these techniques are not always applicable. A new and rapidly developing method that addresses the limitations of these techniques is the electrochemical detection of NPs in solution. The ‘nano-impacts’ technique is an excellent and qualitative in situ method for nanoparticle characterization. Two complementary studies on silver and silver bromide nanoparticles (NPs) were used to assess the large radius limit of the nano-impact method for NP sizing. Noting that by definition a NP cannot be larger than 100 nm in diameter, we have shown that the method quantitatively sizes at the largest limit, the lower limit having been previously reported as ∼6 nm.1 PMID:26491639

Fundamentals, achievements and challenges in the electrochemical sensing of pathogens.

PubMed

Monzó, Javier; Insua, Ignacio; Fernandez-Trillo, Francisco; Rodriguez, Paramaconi

2015-11-07

Electrochemical sensors are powerful tools widely used in industrial, environmental and medical applications. The versatility of electrochemical methods allows for the investigation of chemical composition in real time and in situ. Electrochemical detection of specific biological molecules is a powerful means for detecting disease-related markers. In the last 10 years, highly-sensitive and specific methods have been developed to detect waterborne and foodborne pathogens. In this review, we classify the different electrochemical techniques used for the qualitative and quantitative detection of pathogens. The robustness of electrochemical methods allows for accurate detection even in heterogeneous and impure samples. We present a fundamental description of the three major electrochemical sensing methods used in the detection of pathogens and the advantages and disadvantages of each of these methods. In each section, we highlight recent breakthroughs, including the utilisation of microfluidics, immunomagnetic separation and multiplexing for the detection of multiple pathogens in a single device. We also include recent studies describing new strategies for the design of future immunosensing systems and protocols. The high sensitivity and selectivity, together with the portability and the cost-effectiveness of the instrumentation, enhances the demand for further development in the electrochemical detection of microbes.

Electrochemical Biosensors - Sensor Principles and Architectures

PubMed Central

Grieshaber, Dorothee; MacKenzie, Robert; Vörös, Janos; Reimhult, Erik

2008-01-01

Quantification of biological or biochemical processes are of utmost importance for medical, biological and biotechnological applications. However, converting the biological information to an easily processed electronic signal is challenging due to the complexity of connecting an electronic device directly to a biological environment. Electrochemical biosensors provide an attractive means to analyze the content of a biological sample due to the direct conversion of a biological event to an electronic signal. Over the past decades several sensing concepts and related devices have been developed. In this review, the most common traditional techniques, such as cyclic voltammetry, chronoamperometry, chronopotentiometry, impedance spectroscopy, and various field-effect transistor based methods are presented along with selected promising novel approaches, such as nanowire or magnetic nanoparticle-based biosensing. Additional measurement techniques, which have been shown useful in combination with electrochemical detection, are also summarized, such as the electrochemical versions of surface plasmon resonance, optical waveguide lightmode spectroscopy, ellipsometry, quartz crystal microbalance, and scanning probe microscopy. The signal transduction and the general performance of electrochemical sensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. New nanotechnology-based approaches, such as the use of engineered ion-channels in lipid bilayers, the encapsulation of enzymes into vesicles, polymersomes, or polyelectrolyte capsules provide additional possibilities for signal amplification. In particular, this review highlights the importance of the precise control over the delicate interplay between surface nano-architectures, surface functionalization and the chosen sensor transducer principle, as well as the usefulness of complementary characterization tools to interpret and to optimize the sensor response. PMID:27879772

Electrochemical micro/nano-machining: principles and practices.

PubMed

Zhan, Dongping; Han, Lianhuan; Zhang, Jie; He, Quanfeng; Tian, Zhao-Wu; Tian, Zhong-Qun

2017-03-06

Micro/nano-machining (MNM) is becoming the cutting-edge of high-tech manufacturing because of the increasing industrial demand for supersmooth surfaces and functional three-dimensional micro/nano-structures (3D-MNS) in ultra-large scale integrated circuits, microelectromechanical systems, miniaturized total analysis systems, precision optics, and so on. Taking advantage of no tool wear, no surface stress, environmental friendliness, simple operation, and low cost, electrochemical micro/nano-machining (EC-MNM) has an irreplaceable role in MNM. This comprehensive review presents the state-of-art of EC-MNM techniques for direct writing, surface planarization and polishing, and 3D-MNS fabrications. The key point of EC-MNM is to confine electrochemical reactions at the micro/nano-meter scale. This review will bring together various solutions to "confined reaction" ranging from electrochemical principles through technical characteristics to relevant applications.

Green synthesis of novel zinc iron oxide (ZnFe2O4) nanocomposite via Moringa Oleifera natural extract for electrochemical applications

NASA Astrophysics Data System (ADS)

Matinise, N.; Kaviyarasu, K.; Mongwaketsi, N.; Khamlich, S.; Kotsedi, L.; Mayedwa, N.; Maaza, M.

2018-07-01

The main motivation of the research study involves development of reliable, accurate, inexpensive and environmental friendly method for the synthesis of zinc ferrite (ZnFe2O4) nanocomposites. It was thought of interest to synthesized zinc ferrite via green synthetic method using Moringa Oleifera extract. For the first time, we used green synthetic route via Moringa Oleifera extract acted as both chelating and reducing agents to synthesis spinel ZnFe2O4 nanocomposites. The physical and electrochemical properties were characterized using different techniques such as High Resolve Transmission Electron Microscope (HRTEM) Energy Dispersive X-ray Spectroscopy (EDS) X-ray diffraction (XRD) Fourier transform-infrared (FT-IR) Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The XRD pattern thus clearly illustrated that the ZnFe2O4 nanocmposites synthesized by the green method were good crystalline in nature. The time constant and exchange current of ZnFe2O4 nanocomposites from EIS analysis were calculated and found to be 5.2001 × 10-4 s/rad and 6.59432 × 10-4 A, respectively. Based on the electrochemical results, GCE/ZnFe2O4 electrode exhibited a good voltametric response, high electro-activity, and excellent electrochemical performance making it a highly suitable/promising electrode for electrochemical applications.

Technology transfer opportunities: patent license: electrochemical technique for introducing and redistributing ionic species into the earth

USGS Publications Warehouse

Leinz, Reinhard

1996-01-01

Scientists at the U.S. Geological Survey have expanded applications of the Chim electrode, technology used to perform partial geochemical extractions from soils. Recent applications of the the improved electrode technology show that geochemical extraction efficiencies can be improved by 2 orders of magnitude or better to about 30%.

Peptide-based biosensors: From self-assembled interfaces to molecular probes in electrochemical assays.

PubMed

Puiu, Mihaela; Bala, Camelia

2018-04-01

Redox-tagged peptides have emerged as functional materials with multiple applications in the area of sensing and biosensing applications due to their high stability, excellent redox properties and versatility of biomolecular interactions. They allow direct observation of molecular interactions in a wide range of affinity and enzymatic assays and act as electron mediators. Short helical peptides possess the ability to self-assemble in specific configurations with the possibility to develop in highly-ordered, stable 1D, 2D and 3D architectures in a hierarchical controlled manner. We provide here a brief overview of the electrochemical techniques available to study the electron transfer in peptide films with particular interest in developing biosensors with immobilized peptide motifs, for biological and clinical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Nanoscale Electrochemistry of sp(2) Carbon Materials: From Graphite and Graphene to Carbon Nanotubes.

PubMed

Unwin, Patrick R; Güell, Aleix G; Zhang, Guohui

2016-09-20

Carbon materials have a long history of use as electrodes in electrochemistry, from (bio)electroanalysis to applications in energy technologies, such as batteries and fuel cells. With the advent of new forms of nanocarbon, particularly, carbon nanotubes and graphene, carbon electrode materials have taken on even greater significance for electrochemical studies, both in their own right and as components and supports in an array of functional composites. With the increasing prominence of carbon nanomaterials in electrochemistry comes a need to critically evaluate the experimental framework from which a microscopic understanding of electrochemical processes is best developed. This Account advocates the use of emerging electrochemical imaging techniques and confined electrochemical cell formats that have considerable potential to reveal major new perspectives on the intrinsic electrochemical activity of carbon materials, with unprecedented detail and spatial resolution. These techniques allow particular features on a surface to be targeted and models of structure-activity to be developed and tested on a wide range of length scales and time scales. When high resolution electrochemical imaging data are combined with information from other microscopy and spectroscopy techniques applied to the same area of an electrode surface, in a correlative-electrochemical microscopy approach, highly resolved and unambiguous pictures of electrode activity are revealed that provide new views of the electrochemical properties of carbon materials. With a focus on major sp(2) carbon materials, graphite, graphene, and single walled carbon nanotubes (SWNTs), this Account summarizes recent advances that have changed understanding of interfacial electrochemistry at carbon electrodes including: (i) Unequivocal evidence for the high activity of the basal surface of highly oriented pyrolytic graphite (HOPG), which is at least as active as noble metal electrodes (e.g., platinum) for outer-sphere redox processes. (ii) Demonstration of the high activity of basal plane HOPG toward other reactions, with no requirement for catalysis by step edges or defects, as exemplified by studies of proton-coupled electron transfer, redox transformations of adsorbed molecules, surface functionalization via diazonium electrochemistry, and metal electrodeposition. (iii) Rationalization of the complex interplay of different factors that determine electrochemistry at graphene, including the source (mechanical exfoliation from graphite vs chemical vapor deposition), number of graphene layers, edges, electronic structure, redox couple, and electrode history effects. (iv) New methodologies that allow nanoscale electrochemistry of 1D materials (SWNTs) to be related to their electronic characteristics (metallic vs semiconductor SWNTs), size, and quality, with high resolution imaging revealing the high activity of SWNT sidewalls and the importance of defects for some electrocatalytic reactions (e.g., the oxygen reduction reaction). The experimental approaches highlighted for carbon electrodes are generally applicable to other electrode materials and set a new framework and course for the study of electrochemical and interfacial processes.

Nanoporous Gold: Fabrication, Characterization, and Applications

PubMed Central

Seker, Erkin; Reed, Michael L.; Begley, Matthew R.

2009-01-01

Nanoporous gold (np-Au) has intriguing material properties that offer potential benefits for many applications due to its high specific surface area, well-characterized thiol-gold surface chemistry, high electrical conductivity, and reduced stiffness. The research on np-Au has taken place on various fronts, including advanced microfabrication and characterization techniques to probe unusual nanoscale properties and applications spanning from fuel cells to electrochemical sensors. Here, we provide a review of the recent advances in np-Au research, with special emphasis on microfabrication and characterization techniques. We conclude the paper with a brief outline of challenges to overcome in the study of nanoporous metals.

Tribocorrosion behavior of beta titanium biomedical alloys in phosphate buffer saline solution.

PubMed

Pina, V Guiñón; Dalmau, A; Devesa, F; Amigó, V; Muñoz, A Igual

2015-06-01

The tribo-electrochemical behavior of different β titanium alloys for biomedical applications sintered by powder metallurgy has been investigated. Different mechanical, electrochemical and optical techniques were used to study the influence of the chemical composition, Sn content, and the electrochemical conditions on the tribocorrosion behavior of those alloys Ti30NbxSn alloys (where "x" is the weight percentage of Sn content, 2% and 4%). Sn content increases the active and passive dissolution rate of the titanium alloys, thus increasing the mechanically activated corrosion under tribocorrosion conditions. It also increases the mechanical wear of the alloy. Prevailing electrochemical conditions between -1 and 2V influences the wear accelerated corrosion by increasing it with the applied potential and slightly increases the mechanical wear of Ti30Nb4Sn. Wear accelerated corrosion can be predicted by existing models as a function of electrochemical and mechanical parameters of the titanium alloys. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrochemical behavior and corrosion resistance of Ti-15Mo alloy in naturally-aerated solutions, containing chloride and fluoride ions.

PubMed

Rodrigues, A V; Oliveira, N T C; dos Santos, M L; Guastaldi, A C

2015-01-01

The electrochemical behavior and corrosion resistance of Ti-15Mo alloy to applications as biomaterials in solutions 0.15 mol L(-1) Ringer, 0.15 mol L(-1) Ringer plus 0.036 mol L(-1) NaF and 0.036 mol L(-1) NaF (containing 1,500 ppm of fluoride ions, F(-)) were investigated using open-circuit potential, cyclic voltammetry, and electrochemical impedance spectroscopy techniques, X-ray photoelectron spectroscopy and scanning electron microscope. Corrosion resistance and electrochemical stability of the Ti-15Mo alloy decreased in solutions containing F(-) ions. In all cases, there were formation and growth of TiO2 and MoO3 (a protector film), not being observed pitting corrosion, which might enable Ti-15Mo alloys to be used as biomedical implant, at least in the studied conditions, since the electrochemical stability and corrosion resistance of the passive films formed are necessary conditions for osseointegration.

Preparation and characterizations of activated carbon monolith from rubber wood and its effect on supercapacitor performances

NASA Astrophysics Data System (ADS)

Taer, E.; Taslim, R.; Deraman, M.

2016-02-01

Preparation of activated carbon monolith (ACM) from rubber wood was investigated. Two kind of preparation method were carried out by pre-carbonized of rubber wood saw dust and rubber wood material as it is naturally. The samples were prepared with pelletizing method and small cutting of rubber wood in cross sectional method. Both of samples were characterized by physical and electrochemical technique. The physical properties such as morphology and porosity were investigated. The electrochemical properties of both samples such as equivalent series resistances (ESR) and specific capacitances were also compared. In conclusion, this study showed that both of different preparation method would propose a simple method of ACM electrode preparation technique for supercapacitor applications.

Sandia Laboratories in-house activities in support of solar thermal large power applications

NASA Astrophysics Data System (ADS)

Mar, R. W.

1980-03-01

The development of thermal energy storage subsystems for solar thermal large power applications is described. The emphasis is on characterizing the behavior of molten nitrate salts with regard to thermal decomposition, environmental interactions, and corrosion. Electrochemical techniques to determine the ionic species in the melt and for use in real time studies of corrosion are also briefly discussed.

Sandia Laboratories in-house activities in support of solar thermal large power applications

NASA Technical Reports Server (NTRS)

Mar, R. W.

1980-01-01

The development of thermal energy storage subsystems for solar thermal large power applications is described. The emphasis is on characterizing the behavior of molten nitrate salts with regard to thermal decomposition, environmental interactions, and corrosion. Electrochemical techniques to determine the ionic species in the melt and for use in real time studies of corrosion are also briefly discussed.

Facile synthesis of PdSx/C porous nanospheres and their applications for ethanol oxidation reaction

NASA Astrophysics Data System (ADS)

Zhang, Qiang; Zhang, Fuhua; Ma, Xuemei; Zheng, Yiqun; Hou, Shifeng

2016-12-01

We report a facile approach for the synthesis of carbon-supported palladium polysulphide porous nanospheres (PdSx/C) and their applications for ethanol oxidation reaction. Typical synthesis started with generation of palladium/poly (3,4-ethylenedioxythiophene)(Pd/PEDOT) nanospheres, followed by a calcination process at an optimized temperature to form PdSx/C, with an average size of 2.47 ± 0.60 and 50 nm of PdSx nanoparticles and carbon porous nanospheres, respectively. Various techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical techniques were performed to characterize their morphologies, compositions and structures. In contrary to most Pd-based electrochemical catalysts that could be easily poised with trace sulfur during the catalytic oxidation process, the as-prepared PdSx/C porous nanospheres exhibited high electrocatalytic activities and stabilities for the electrochemical catalytic oxidation of ethanol in alkaline medium. In particular, the forward peak current intensity achieved 162.1 mA mg-1 and still maintained at 46.7 mA mg-1 even after 1000 cycles. This current work not only offers a novel type of fuel-cell catalyst for ethanol oxidation reaction, but also provides a possible route for solving the sulfur-poisoning problem in catalysis.

Synthesis and Characterization of Mn3O4 - Graphene Core - Shell Quantum Dots for Electrochemical Pseudocapacitor Applications

NASA Astrophysics Data System (ADS)

Ko, Yohan; Son, Dong Ick

2018-05-01

We report on the in-situ chemical growth of unique core-shell quantum dots (QDs) with single layer graphene on the surfaces of the Mn3O4 QDs and on their structural, optical and electrical properties. The Mn3O4-graphene QDs were synthesized through a simple hydrothermal technique. In order to enhance performance for electrochemical energy storage, we developed core (active material) - shell (conductive material)-type Mn3O4 - graphene QDs as electrode materials by using an aqueous electrolyte (6M KOH). As a result, the performance of electrochemical energy storage exhibit a specific capacitance of 452.72 Fg-1 at a current density of 1 Ag-1.

Exploration of two-dimensional bio-functionalized phosphorene nanosheets (black phosphorous) for label free haptoglobin electro-immunosensing applications

NASA Astrophysics Data System (ADS)

Tuteja, Satish K.; Neethirajan, Suresh

2018-04-01

We report on the development of an antibody-functionalized interface based on electrochemically active liquid-exfoliated two-dimensional phosphorene (Ph) nanosheets—also known as black phosphorous nanosheets—for the label-free electrochemical immunosensing of a haptoglobin (Hp) biomarker, a clinical marker of severe inflammation. The electrodeposition has been achieved over the screen-printed electrode (SPE) using liquid-assisted ultrasonically exfoliated black phosphorus nanosheets. Subsequently, Ph-SPEs bioconjugated with Hp antibodies (Ab), using electrostatic interactions via a poly-L-lysine linker for biointerface development. Electrochemical analysis demonstrates that the Ab-modified Ph-SPEs (Ab@Ph-SPE) exhibit enhanced electroconducting behavior as compared to the pristine electrodes. This Ab-functionalized phosphorene-based electrochemical immunosensor platform has demonstrated remarkable sensitivity and specificity, having a dynamic linear response range from 0.01-10 mg ml-1 for Hp in standard and serum samples with a low detection limit (˜0.011 mg ml-1) using the label-free electrochemical technique. The sensor electrodes were also studied with other closely relative interferents to investigate cross reactivity and specificity. This strategy opens up avenues to POC (point-of-care) and on-farm livestock disease monitoring technologies for multiplexed diagnosis in complex biological samples such as serum. The technique is simple in fabrication and provides an analytical response in less than 60 s.

Electrochemical synthesis of MoS2 quantum dots embedded nanostructured porous silicon with enhanced electroluminescence property

NASA Astrophysics Data System (ADS)

Shrivastava, Megha; Kumari, Reeta; Parra, Mohammad Ramzan; Pandey, Padmini; Siddiqui, Hafsa; Haque, Fozia Z.

2017-11-01

In this report we present the successful enhancement in electroluminescence (EL) in nanostructured n-type porous silicon (PS) with an idea of embedding luminophorous Molybdenum disulfide (MoS2) quantum dots (QD's). Electrochemical anodization technique was used for the formation of PS surface and MoS2 QD's were prepared using the electrochemical route. Spin coating technique was employed for the proper incorporation of MoS2 QD's within the PS nanostructures. The crystallographic analysis was performed using X-ray diffraction (XRD), Raman and Fourier transform infrared (FT-IR) spectroscopy techniques. However, surface morphology was determined using Transmission electron microscopy (TEM) and Atomic force microscopy (AFM). The optical measurements were performed on photoluminescence (PL) spectrophotometer; additionally for electroluminescence (EL) study special arrangement of instrumental setup was made at laboratory level which provides novelty to this work. A diode prototype was made comprising Ag/MoS2:PS/Silicon/Ag for EL study. The MoS2:PS shows a remarkable concentration dependent enhancement in PL as well as in EL intensities, which paves a way to better utilize this strategy in optoelectronic device applications.

Electrochemical Determination of Pentachlorophenol in Water on a Multi-Wall Carbon Nanotubes-Epoxy Composite Electrode

PubMed Central

Remes, Adriana; Pop, Aniela; Manea, Florica; Baciu, Anamaria; Picken, Stephen J.; Schoonman, Joop

2012-01-01

The aim of this study was the preparation, characterization, and application of a multi-wall carbon nanotubes-epoxy composite electrode (MWCNT-EP) with 25%, wt. MWCNTs loading for the voltammetric/amperometric determination of pentachlorophenol (PCP) in aqueous solutions. The structural and morphological aspects of the MWCNT-EP composite electrode were examined by scanning electron microscopy. The electrical properties were characterized by direct-current conductivity measurements in relation with the percolation threshold. The electrochemical behavior of PCP at the MWCNT-EP composite electrode was investigated using cyclic voltammetry in 0.1 M Na2SO4 supporting electrolyte in order to establish the parameters for amperometric/voltammetric determination of PCP. The linear dependence of current vs. PCP concentrations was reached in a wide concentration range from 0.2 to 12 μM PCP using cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry, chronoamperometry, and multiple-pulsed amperometry techniques. The best electroanalytical performances of this composite electrode were achieved using a pre-concentration/square-wave voltammetric technique and also multiple-pulsed amperometry techniques envisaging the practical applications. The ease of preparation, high sensitivity, and stability of this composite electrode should open novel avenues and applications for fabricating robust sensors for detection of many important species. PMID:22969335

Electrochemical Sensors and Biosensors Based on Nanomaterials and Nanostructures

DOE PAGES

Zhu, Chengzhou; Yang, Guohai; Li, He; ...

2014-10-29

We report that considerable attention has been devoted to the integration of recognition elements with electronic elements to develop electrochemical sensors and biosensors.Various electrochemical devices, such as amperometric sensors, electrochemical impedance sensors, and electrochemical luminescence sensors as well as photoelectrochemical sensors, provide wide applications in the detection of chemical and biological targets in terms of electrochemical change of electrode interfaces. Here, this review focuses on recent advances in electrochemical sensors and biosensors based on nanomaterials and nanostructures during 2013 to 2014. The aim of this effort is to provide the reader with a clear and concise view of new advancesmore » in areas ranging from electrode engineering, strategies for electrochemical signal amplification, and novel electroanalytical techniques used in the miniaturization and integration of the sensors. Moreover, the authors have attempted to highlight areas of the latest and significant development of enhanced electrochemical nanosensors and nanobiosensors that inspire broader interests across various disciplines. Electrochemical sensors for small molecules, enzyme-based biosensors, genosensors, immunosensors, and cytosensors are reviewed herein (Figure 1). Such novel advances are important for the development of electrochemical sensors that open up new avenues and methods for future research. In conclusion, we recommend readers interested in the general principles of electrochemical sensors and electrochemical methods to refer to other excellent literature for a broad scope in this area.(3, 4) However, due to the explosion of publications in this active field, we do not claim that this Review includes all of the published works in the past two years and we apologize to the authors of excellent work, which is unintentionally left out.« less

Strategies for the removal of halides from drinking water sources, and their applicability in disinfection by-product minimisation: a critical review.

PubMed

Watson, K; Farré, M J; Knight, N

2012-11-15

The presence of bromide (Br(-)) and iodide (I(-)) in source waters leads to the formation of brominated and iodinated disinfection by-products (DBPs), which are often more toxic than their chlorinated analogues. The increasing scarcity of water resources in Australia is leading to use of impaired and alternative water supplies with high bromide and iodide levels, which may result in the production of more brominated and iodinated DBPs. This review aims to provide a summary of research into bromide and iodide removal from drinking water sources. Bromide and iodide removal techniques have been broadly classified into three categories, namely; membrane, electrochemical and adsorptive techniques. Reverse osmosis, nanofiltration and electrodialysis membrane techniques are reviewed. The electrochemical techniques discussed are electrolysis, capacitive deionization and membrane capacitive deionization. Studies on bromide and iodide removal using adsorptive techniques including; layered double hydroxides, impregnated activated carbons, carbon aerogels, ion exchange resins, aluminium coagulation and soils are also assessed. Halide removal techniques have been compared, and areas for future research have been identified. Copyright © 2012 Elsevier Ltd. All rights reserved.

Lignin and silicate based hydrogels for biosensor applications

NASA Astrophysics Data System (ADS)

Burrs, S. L.; Jairam, S.; Vanegas, D. C.; Tong, Z.; McLamore, E. S.

2013-05-01

Advances in biocompatible materials and electrocatalytic nanomaterials have extended and enhanced the field of biosensors. Immobilization of biorecognition elements on nanomaterial platforms is an efficient technique for developing high fidelity biosensors. Single layer (i.e., Langmuir-Blodgett) protein films are efficient, but disadvantages of this approach include high cost, mass transfer limitations, and Vromer competition for surface binding sites. There is a need for simple, user friendly protein-nanomaterial sensing membranes that can be developed in laboratories or classrooms (i.e., outside of the clean room). In this research, we develop high fidelity nanomaterial platforms for developing electrochemical biosensors using sustainable biomaterials and user-friendly deposition techniques. Catalytic nanomaterial platforms are developed using a combination of self assembled monolayer chemistry and electrodeposition. High performance biomaterials (e.g., nanolignin) are recovered from paper pulp waste and combined with proteins and nanomaterials to form active sensor membranes. These methods are being used to develop electrochemical biosensors for studying physiological transport in biomedical, agricultural, and environmental applications.

Efficient Transport Networks in a Dual Electron/Lithium-Conducting Polymeric Composite for Electrochemical Applications.

PubMed

McDonald, Michael B; Hammond, Paula T

2018-05-09

In this work, an all-functional polymer material composed of the electrically conductive poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid) (PEDOT:PSS) and lithium-conducting poly(ethylene oxide) (PEO) was developed to form a dual conductor for three-dimensional electrodes in electrochemical applications. The composite exhibits enhanced ionic conductivity (∼10 -4 S cm -1 ) and, counterintuitively, electronic conductivity (∼45 S cm -1 ) with increasing PEO proportion, optimal at a monomer ratio of 20:1 PEO:PEDOT. Microscopy reveals a unique morphology, where PSS interacts favorably with PEO, destabilizing PEDOT to associate into highly branched, interconnected networks that allow for more efficient electronic transport despite relatively low concentrations. Thermal and X-ray techniques affirm that the PSS-PEO domain suppresses crystallinity, explaining the high ionic conductivity. Electrochemical experiments in lithium cell environments indicate stability as a function of cycling and improved overpotential due to dual transport characteristics despite known issues with both individual components.

Bioelectronic platforms for optimal bio-anode of bio-electrochemical systems: From nano- to macro scopes.

PubMed

Kim, Bongkyu; An, Junyeong; Fapyane, Deby; Chang, In Seop

2015-11-01

The current trend of bio-electrochemical systems is to improve strategies related to their applicability and potential for scaling-up. To date, literature has suggested strategies, but the proposal of correlations between each research field remains insufficient. This review paper provides a correlation based on platform techniques, referred to as bio-electronics platforms (BEPs). These BEPs consist of three platforms divided by scope scale: nano-, micro-, and macro-BEPs. In the nano-BEP, several types of electron transfer mechanisms used by electrochemically active bacteria are discussed. In the micro-BEP, factors affecting the formation of conductive biofilms and transport of electrons in the conductive biofilm are investigated. In the macro-BEP, electrodes and separators in bio-anode are debated in terms of real applications, and a scale-up strategy is discussed. Overall, the challenges of each BEP are highlighted, and potential solutions are suggested. In addition, future research directions are provided and research ideas proposed to develop research interest. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrochemical Study and Applications of Selective Electrodeposition of Silver on Quantum Dots.

PubMed

Martín-Yerga, Daniel; Rama, Estefanía Costa; Costa-García, Agustín

2016-04-05

In this work, selective electrodeposition of silver on quantum dots is described. The particular characteristics of the nanostructured silver thus obtained are studied by electrochemical and microscopic techniques. On one hand, quantum dots were found to catalyze the silver electrodeposition, and on the other hand, a strong adsorption between electrodeposited silver and quantum dots was observed, indicated by two silver stripping processes. Nucleation of silver nanoparticles followed different mechanisms depending on the surface (carbon or quantum dots). Voltammetric and confocal microscopy studies showed the great influence of electrodeposition time on surface coating, and high-resolution transmission electron microscopy (HRTEM) imaging confirmed the initial formation of Janus-like Ag@QD nanoparticles in this process. By use of moderate electrodeposition conditions such as 50 μM silver, -0.1 V, and 60 s, the silver was deposited only on quantum dots, allowing the generation of localized nanostructured electrode surfaces. This methodology can also be employed for sensing applications, showing a promising ultrasensitive electrochemical method for quantum dot detection.

Kelvin Probe Force Microscopy in liquid using Electrochemical Force Microscopy

DOE PAGES

Collins, Liam; Jesse, Stephen; Kilpatrick, J.; ...

2015-01-19

Conventional closed loop-Kelvin probe force microscopy (KPFM) has emerged as a powerful technique for probing electric and transport phenomena at the solid-gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid–liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe-sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present). Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q watermore » and aqueous NaCl) and ionically-inactive (non-polar decane) liquids by electrochemical force microscopy (EcFM), a multidimensional (i.e., bias- and time-resolved) spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids), KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD) values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions). EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid–liquid interface.« less

Technological advancement in electrochemical biosensor based detection of Organophosphate pesticide chlorpyrifos in the environment: A review of status and prospects.

PubMed

Uniyal, Shivani; Sharma, Rajesh Kumar

2018-09-30

Chlorpyrifos (CP), an organophosphate insecticide is broadly used in the agricultural and industrial sectors to control a broad-spectrum of insects of economically important crops. CP detection has been gaining prominence due to its widespread contamination in different environmental matrices, high acute toxicity, and potential to cause long-term environmental and ecological damage even at trace levels. Traditional chromatographic methods for CP detection are complex and require sample preparation and highly skilled personnel for their operation. Over the past decades, electrochemical biosensors have emerged as a promising technology for CP detection as these circumvent deficiencies associated with classical chromatographic techniques. The advantageous features such as appreciable detection limit, miniaturization, sensitivity, low-cost and onsite detection potential are the propulsive force towards sustainable growth of electrochemical biosensing platforms. Recent development in enzyme immobilization methods, novel surface modifications, nanotechnology and fabrication techniques signify a foremost possibility for the design of electrochemical biosensing platforms with improved sensitivity and selectivity. The prime objective of this review is to accentuate the recent advances in the design of biosensing platforms based on diverse biomolecules and biomimetic molecules with unique properties, which would potentially fascinate their applicability for detection of CP residues in real samples. The review also covers the sensing principle of the prime biomolecule and biomimetic molecule based electrochemical biosensors along with their analytical performance, advantages and shortcomings. Present challenges and future outlooks in the field of electrochemical biosensors based CP detection are also discussed. This deep analysis of electrochemical biosensors will provide research directions for further approaching towards commercial development of the broad range of organophosphorus compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

Mass spectrometric methods for monitoring redox processes in electrochemical cells.

PubMed

Oberacher, Herbert; Pitterl, Florian; Erb, Robert; Plattner, Sabine

2015-01-01

Electrochemistry (EC) is a mature scientific discipline aimed to study the movement of electrons in an oxidation-reduction reaction. EC covers techniques that use a measurement of potential, charge, or current to determine the concentration or the chemical reactivity of analytes. The electrical signal is directly converted into chemical information. For in-depth characterization of complex electrochemical reactions involving the formation of diverse intermediates, products and byproducts, EC is usually combined with other analytical techniques, and particularly the hyphenation of EC with mass spectrometry (MS) has found broad applicability. The analysis of gases and volatile intermediates and products formed at electrode surfaces is enabled by differential electrochemical mass spectrometry (DEMS). In DEMS an electrochemical cell is sampled with a membrane interface for electron ionization (EI)-MS. The chemical space amenable to EC/MS (i.e., bioorganic molecules including proteins, peptides, nucleic acids, and drugs) was significantly increased by employing electrospray ionization (ESI)-MS. In the simplest setup, the EC of the ESI process is used to analytical advantage. A limitation of this approach is, however, its inability to precisely control the electrochemical potential at the emitter electrode. Thus, particularly for studying mechanistic aspects of electrochemical processes, the hyphenation of discrete electrochemical cells with ESI-MS was found to be more appropriate. The analytical power of EC/ESI-MS can further be increased by integrating liquid chromatography (LC) as an additional dimension of separation. Chromatographic separation was found to be particularly useful to reduce the complexity of the sample submitted either to the EC cell or to ESI-MS. Thus, both EC/LC/ESI-MS and LC/EC/ESI-MS are common. © 2013 The Authors. Mass Spectrometry Reviews published by Wiley Periodicals, Inc.

Mass spectrometric methods for monitoring redox processes in electrochemical cells

PubMed Central

Oberacher, Herbert; Pitterl, Florian; Erb, Robert; Plattner, Sabine

2015-01-01

Electrochemistry (EC) is a mature scientific discipline aimed to study the movement of electrons in an oxidation–reduction reaction. EC covers techniques that use a measurement of potential, charge, or current to determine the concentration or the chemical reactivity of analytes. The electrical signal is directly converted into chemical information. For in-depth characterization of complex electrochemical reactions involving the formation of diverse intermediates, products and byproducts, EC is usually combined with other analytical techniques, and particularly the hyphenation of EC with mass spectrometry (MS) has found broad applicability. The analysis of gases and volatile intermediates and products formed at electrode surfaces is enabled by differential electrochemical mass spectrometry (DEMS). In DEMS an electrochemical cell is sampled with a membrane interface for electron ionization (EI)-MS. The chemical space amenable to EC/MS (i.e., bioorganic molecules including proteins, peptides, nucleic acids, and drugs) was significantly increased by employing electrospray ionization (ESI)-MS. In the simplest setup, the EC of the ESI process is used to analytical advantage. A limitation of this approach is, however, its inability to precisely control the electrochemical potential at the emitter electrode. Thus, particularly for studying mechanistic aspects of electrochemical processes, the hyphenation of discrete electrochemical cells with ESI-MS was found to be more appropriate. The analytical power of EC/ESI-MS can further be increased by integrating liquid chromatography (LC) as an additional dimension of separation. Chromatographic separation was found to be particularly useful to reduce the complexity of the sample submitted either to the EC cell or to ESI-MS. Thus, both EC/LC/ESI-MS and LC/EC/ESI-MS are common. PMID:24338642

Electrochemical Characterization of a Low Modulus Ti-35.5Nb-7.3Zr-5.7Ta Alloy in a Simulated Body Fluid Using Eis for Biomedical Applications

NASA Astrophysics Data System (ADS)

Bhola, R.; Bhola, S. M.; Mishra, B.; Ayers, R. A.; Olson, D. L.

2011-06-01

Electrochemical characterization of the low modulus Ti-35.5Nb-7.3Zr-5.7Ta beta alloy (TNZT) has been performed in phosphate buffer saline solution at 37 °C using the non destructive electrochemical impedance spectroscopy technique. Measurements were performed at various immersion intervals at the open circuit potential (OCP), which was also monitored with time. Results obtained for TNZT alloy have been compared with those for the commercially used Ti-6Al-4V mixed alloy (Ti64) and the commercially pure titanium (Ti2) alpha alloy. Potentiodynamic polarization was performed to supplement the data obtained from EIS analysis. The TNZT alloy exhibits a two time constant impedance response, whereas the Ti64 and Ti2 alloys display a one time constant behavior. Human fetal osteoblast cells show a better adhesion and a higher cell count for the TNZT alloy compared to the other two alloys. The present investigation is an effort to understand the correlation between the electrochemical, morphological and cellular characteristics of titanium alloys to qualify them for implant applications.

The self-assembly of redox active peptides: Synthesis and electrochemical capacitive behavior.

PubMed

Piccoli, Julia P; Santos, Adriano; Santos-Filho, Norival A; Lorenzón, Esteban N; Cilli, Eduardo M; Bueno, Paulo R

2016-05-01

The present work reports on the synthesis of a redox-tagged peptide with self-assembling capability aiming applications in electrochemically active capacitive surfaces (associated with the presence of the redox centers) generally useful in electroanalytical applications. Peptide containing ferrocene (fc) molecular (redox) group (Ac-Cys-Ile-Ile-Lys(fc)-Ile-Ile-COOH) was thus synthesized by solid phase peptide synthesis (SPPS). To obtain the electrochemically active capacitive interface, the side chain of the cysteine was covalently bound to the gold electrode (sulfur group) and the side chain of Lys was used to attach the ferrocene in the peptide chain. After obtaining the purified redox-tagged peptide, the self-assembly and redox capability was characterized by cyclic voltammetry (CV) and electrochemical impedance-based capacitance spectroscopy techniques. The obtained results confirmed that the redox-tagged peptide was successfully attached by forming an electroactive self-assembled monolayer onto gold electrode. The design of redox active self-assembly ferrocene-tagged peptide is predictably useful in the development of biosensor devices precisely to detect, in a label-free platform, those biomarkers of clinical relevance. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 357-367, 2016. © 2016 Wiley Periodicals, Inc.

GaN light-emitting device based on ionic liquid electrolyte

NASA Astrophysics Data System (ADS)

Hirai, Tomoaki; Sakanoue, Tomo; Takenobu, Taishi

2018-06-01

Ionic liquids (ILs) are attractive materials for fabricating unique hybrid devices based on electronics and electrochemistry; thus, IL-gated transistors and organic light-emitting devices of light-emitting electrochemical cells (LECs) are investigated for future low-voltage and high-performance devices. In LECs, voltage application induces the formation of electrochemically doped p–n homojunctions owing to ion rearrangements in composites of semiconductors and electrolytes, and achieves electron–hole recombination for light emission at the homojunctions. In this work, we applied this concept of IL-induced electrochemical doping to the fabrication of GaN-based light-emitting devices. We found that voltage application to the layered IL/GaN structure accumulated electrons on the GaN surface owing to ion rearrangements and improved the conductivity of GaN. The ion rearrangement also enabled holes to be injected by the strong electric field of electric double layers on hole injection contacts. This simultaneous injection of holes and electrons into GaN mediated by ions achieves light emission at a low voltage of around 3.4 V. The light emission from the simple IL/GaN structure indicates the usefulness of an electrochemical technique in generating light emission with great ease of fabrication.

Highly crumpled solar reduced graphene oxide electrode for supercapacitor application

NASA Astrophysics Data System (ADS)

Mohanapriya, K.; Ahirrao, Dinesh J.; Jha, Neetu

2018-04-01

Highly crumpled solar reduced graphene oxide (CSRGO) was synthesized by simple and rapid method through freezing the solar reduced graphene oxide aqueous suspension using liquid nitrogen and used as electrode material for supercapacitor application. This electrode material was characterized by transmission electron microscope (TEM), X-Ray diffractometer (XRD) and Raman Spectroscopy techniques to understand the morphology and structure. The electrochemical performance was studied by cyclic voltammetry (CV), galvanostatic charge/discharge (CD) and electrochemical impedance spectroscopy (EIS) using 6M KOH electrolyte. The CSRGO exhibit high specifc capacitance of 210.1 F g-1 at the current density of 0.5 A g-1 and shows excellent rate capability. These features make the CSRGO material as promising electrode for high-performance supercapacitors.

Facile synthesis of nickel-based metal organic framework [Ni3(HCOO)6] by microwave method and application for supercapacitor

NASA Astrophysics Data System (ADS)

Luo, Jujie; Yang, Xing; Wang, Shumin; Bi, Yuhong; Nautiyal, Amit; Zhang, Xinyu

The metal organic framework (MOF) [Ni3(HCOO)6] was synthesized via the simple and fast microwave method, and the effect of irradiation power on crystallinity of synthesized Ni-based MOF was studied. The samples were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The synthesized Ni-based MOF was electrochemically characterized by using galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. The synthesized MOF showed the highest specific capacitance of 1196.2F/g at 1A/g with excellent cyclability (86.04% capacitance retention after 2,000 cycles), thereby demonstrating its potential application in supercapacitors.

Continuous piecewise-linear, reduced-order electrochemical model for lithium-ion batteries in real-time applications

NASA Astrophysics Data System (ADS)

Farag, Mohammed; Fleckenstein, Matthias; Habibi, Saeid

2017-02-01

Model-order reduction and minimization of the CPU run-time while maintaining the model accuracy are critical requirements for real-time implementation of lithium-ion electrochemical battery models. In this paper, an isothermal, continuous, piecewise-linear, electrode-average model is developed by using an optimal knot placement technique. The proposed model reduces the univariate nonlinear function of the electrode's open circuit potential dependence on the state of charge to continuous piecewise regions. The parameterization experiments were chosen to provide a trade-off between extensive experimental characterization techniques and purely identifying all parameters using optimization techniques. The model is then parameterized in each continuous, piecewise-linear, region. Applying the proposed technique cuts down the CPU run-time by around 20%, compared to the reduced-order, electrode-average model. Finally, the model validation against real-time driving profiles (FTP-72, WLTP) demonstrates the ability of the model to predict the cell voltage accurately with less than 2% error.

Spectroelectrochemical Sensing of Aqueous Iron: An Experiment for Analytical Chemistry

ERIC Educational Resources Information Center

Shtoyko, Tanya; Stuart, Dean; Gray, H. Neil

2007-01-01

We have designed a laboratory experiment to illustrate the use of spectroelectrochemical techniques for determination of aqueous iron. The experiment described in this article is applicable to an undergraduate laboratory course in analytical chemistry. Students are asked to fabricate spectroelectrochemical sensors, make electrochemical and optical…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Min, Ji Won; Kalathil, Abdul Kareem; Yim, Chul Jin

Li-rich Li{sub 1.2}Ni{sub 0.17}Co{sub 0.17}Mn{sub 0.5}O{sub 2} cathode materials were synthesized by electrospinning technique with different polymers, and their structural, morphological, and electrochemical performances were investigated. It was found that the electrospinning process leads to the formation of a fiber and flower-like morphology, by using different polymers and heat treatment conditions. The nanostructured morphology provided these materials with high initial discharge capacity. The cycling stability was improved with agglomerated nano-particles, as compared with porous materials. - Highlights: • Fiber and flower-like Li-rich cathode was synthesized by simple electrospinning. • Polymer dependent morphology and electrochemical performance was investigated. • Well-organized porousmore » structure facilitates the diffusion of lithium ions. • Technique could be applicable to other cathode materials as well.« less

Universal mobile electrochemical detector designed for use in resource-limited applications

PubMed Central

Nemiroski, Alex; Christodouleas, Dionysios C.; Hennek, Jonathan W.; Kumar, Ashok A.; Maxwell, E. Jane; Fernández-Abedul, Maria Teresa; Whitesides, George M.

2014-01-01

This paper describes an inexpensive, handheld device that couples the most common forms of electrochemical analysis directly to “the cloud” using any mobile phone, for use in resource-limited settings. The device is designed to operate with a wide range of electrode formats, performs on-board mixing of samples by vibration, and transmits data over voice using audio—an approach that guarantees broad compatibility with any available mobile phone (from low-end phones to smartphones) or cellular network (second, third, and fourth generation). The electrochemical methods that we demonstrate enable quantitative, broadly applicable, and inexpensive sensing with flexibility based on a wide variety of important electroanalytical techniques (chronoamperometry, cyclic voltammetry, differential pulse voltammetry, square wave voltammetry, and potentiometry), each with different uses. Four applications demonstrate the analytical performance of the device: these involve the detection of (i) glucose in the blood for personal health, (ii) trace heavy metals (lead, cadmium, and zinc) in water for in-field environmental monitoring, (iii) sodium in urine for clinical analysis, and (iv) a malarial antigen (Plasmodium falciparum histidine-rich protein 2) for clinical research. The combination of these electrochemical capabilities in an affordable, handheld format that is compatible with any mobile phone or network worldwide guarantees that sophisticated diagnostic testing can be performed by users with a broad spectrum of needs, resources, and levels of technical expertise. PMID:25092346

Ion/proton-conducting apparatus and method

DOEpatents

Yates, Matthew; Xue, Wei

2014-12-23

A c-axis-oriented HAP thin film synthesized by seeded growth on a palladium hydrogen membrane substrate. An exemplary synthetic process includes electrochemical seeding on the substrate, and secondary and tertiary hydrothermal treatments under conditions that favor growth along c-axes and a-axes in sequence. By adjusting corresponding synthetic conditions, an HAP this film can be grown to a controllable thickness with a dense coverage on the underlying substrate. The thin films have relatively high proton conductivity under hydrogen atmosphere and high temperature conditions. The c-axis oriented films may be integrated into fuel cells for application in the intermediate temperature range of 200-600.degree. C. The electrochemical-hydrothermal deposition technique may be applied to create other oriented crystal materials having optimized properties, useful for separations and catalysis as well as electronic and electrochemical applications, electrochemical membrane reactors, and in chemical sensors. Additional high-density and gas-tight HAP film compositions may be deposited using a two-step deposition method that includes an electrochemical deposition method followed by a hydrothermal deposition method. The two-step method uses a single hydrothermal deposition solution composition. The method may be used to deposit HAP films including but not limited to at least doped HAP films, and more particularly including carbonated HAP films. In addition, the high-density and gas-tight HAP films may be used in proton exchange membrane fuel cells.

A Highly-Sensitive Picric Acid Chemical Sensor Based on ZnO Nanopeanuts.

PubMed

Ibrahim, Ahmed A; Tiwari, Preeti; Al-Assiri, M S; Al-Salami, A E; Umar, Ahmad; Kumar, Rajesh; Kim, S H; Ansari, Z A; Baskoutas, S

2017-07-13

Herein, we report a facile synthesis, characterization, and electrochemical sensing application of ZnO nanopeanuts synthesized by a simple aqueous solution process and characterized by various techniques in order to confirm the compositional, morphological, structural, crystalline phase, and optical properties of the synthesized material. The detailed characterizations revealed that the synthesized material possesses a peanut-shaped morphology, dense growth, and a wurtzite hexagonal phase along with good crystal and optical properties. Further, to ascertain the useful properties of the synthesized ZnO nanopeanut as an excellent electron mediator, electrochemical sensors were fabricated based on the form of a screen printed electrode (SPE). Electrochemical and current-voltage characteristics were studied for the determination of picric acid sensing characteristics. The electrochemical sensor fabricated based on the SPE technique exhibited a reproducible and reliable sensitivity of ~1.2 μA/mM (9.23 μA·mM -1 ·cm -2 ), a lower limit of detection at 7.8 µM, a regression coefficient ( R ²) of 0.94, and good linearity over the 0.0078 mM to 10.0 mM concentration range. In addition, the sensor response was also tested using simple I-V techniques, wherein a sensitivity of 493.64 μA·mM -1 ·cm -2 , an experimental Limit of detection (LOD) of 0.125 mM, and a linear dynamic range (LDR) of 1.0 mM-5.0 mM were observed for the fabricated picric acid sensor.

A Highly-Sensitive Picric Acid Chemical Sensor Based on ZnO Nanopeanuts

PubMed Central

Ibrahim, Ahmed A.; Tiwari, Preeti; Al-Assiri, M. S.; Al-Salami, A. E.; Umar, Ahmad; Kumar, Rajesh; Kim, S. H.; Ansari, Z. A.; Baskoutas, S.

2017-01-01

Herein, we report a facile synthesis, characterization, and electrochemical sensing application of ZnO nanopeanuts synthesized by a simple aqueous solution process and characterized by various techniques in order to confirm the compositional, morphological, structural, crystalline phase, and optical properties of the synthesized material. The detailed characterizations revealed that the synthesized material possesses a peanut-shaped morphology, dense growth, and a wurtzite hexagonal phase along with good crystal and optical properties. Further, to ascertain the useful properties of the synthesized ZnO nanopeanut as an excellent electron mediator, electrochemical sensors were fabricated based on the form of a screen printed electrode (SPE). Electrochemical and current-voltage characteristics were studied for the determination of picric acid sensing characteristics. The electrochemical sensor fabricated based on the SPE technique exhibited a reproducible and reliable sensitivity of ~1.2 μA/mM (9.23 μA·mM−1·cm−2), a lower limit of detection at 7.8 µM, a regression coefficient (R2) of 0.94, and good linearity over the 0.0078 mM to 10.0 mM concentration range. In addition, the sensor response was also tested using simple I-V techniques, wherein a sensitivity of 493.64 μA·mM−1·cm−2, an experimental Limit of detection (LOD) of 0.125 mM, and a linear dynamic range (LDR) of 1.0 mM–5.0 mM were observed for the fabricated picric acid sensor. PMID:28773151

Association of Electrochemical Therapy With Optical, Mechanical, and Acoustic Impedance Properties of Porcine Skin.

PubMed

Moy, Wesley J; Su, Erica; Chen, Jason J; Oh, Connie; Jing, Joe C; Qu, Yueqiao; He, Youmin; Chen, Zhongping; Wong, Brian J F

2017-12-01

The classic management of burn scars and other injuries to the skin has largely relied on soft-tissue transfer to resurface damaged tissue with local tissue transfer or skin graft placement. In situ generation of electrochemical reactions using needle electrodes and an application of current may be a new approach to treat scars and skin. To examine the changes in optical, mechanical, and acoustic impedance properties in porcine skin after electrochemical therapy. This preclinical pilot study, performed from August 1, 2015, to November 1, 2016, investigated the effects of localized pH-driven electrochemical therapy of ex vivo porcine skin using 24 skin samples. Platinum-plated needle electrodes were inserted into fresh porcine skin samples. A DC power supply provided a voltage of 4 to 5 V with a 3-minute application time. Specimens were analyzed using optical coherence tomography, optical coherence elastography, and ultrasonography. Ultrasonography was performed under 3 conditions (n = 2 per condition), optical coherence tomography was performed under 2 conditions (n = 2 per condition), and optical coherence elastography was performed under 2 conditions (n = 2 per condition). The remaining samples were used for the positive and negative control groups (n = 10). Platinum-plated needle electrodes were inserted into fresh porcine skin samples. A DC power supply provided a voltage of 4 to 5 V with a 3-minute application. Tissue softening was observed at the anode and cathode sites as a result of electrochemical modification. Volumetric changes were noted using each optical and acoustic technique. A total of 24 ex vivo porcine skin samples were used for this pilot study. Optical coherence tomography measured spatial distribution of superficial tissue changes around each electrode site. At 4 V for 3 minutes, a total volumetric effect of 0.47 mm3 was found at the anode site and 0.51 mm3 at the cathode site. For 5 V for 3 minutes, a total volumetric effect of 0.85 mm3 was found at the anode site and 1.05 mm3 at the cathode site. Electrochemical therapy is a low-cost technique that is on par with the costs of suture and scalpel. The use of electrochemical therapy to create mechanical and physiologic changes in tissue has the potential to locally remodel the soft-tissue matrix, which ultimately may lead to an inexpensive scar treatment or skin rejuvenation therapy. NA.

Effect of MWCNT on prepared cathode material (Li2Mn(x)Fe(1-x)SiO4) for energy storage applications

NASA Astrophysics Data System (ADS)

Agnihotri, Shruti; Rattan, Sangeeta; Sharma, A. L.

2016-05-01

The electrode material Li2MnFeSiO4 was successfully synthesized by standard sol-gel method and further modified with multiwalled carbon nano tube (MWCNT) to achieve better electrochemical properties. Our strategy helps us to improve the performance and storage capacity as compared with the bared material. This novel composite structure constructs an efficient cation (Li+) and electron channel which significantly enhance the Li+ ion diffusion coefficient and reduced charge transfer resistance. Hence leads to high conductivity and specific capacity. Characterization technique like Field emission scanning electron microscopy (FESEM) has been used to confirm its morphology, structure and particle size which comes out to be of the order of ˜20 to 30 nm. Lesser particle size reveals better electrochemical properties. Electrical conductivity (˜10-5 Scm-1) of MWCNT doped oxide cathode materials was recorded using ac impedance spectroscopy technique which reflects tenfold increment when compared with pure oxide cathode materials. Cyclic voltametery analysis has been done to calculate specific capacity and potential window of materials with and without CNTs. The results obtained from different techniques are well correlated and suitable for energy storage applications.

Magnetic Particles Coupled to Disposable Screen Printed Transducers for Electrochemical Biosensing

PubMed Central

Yáñez-Sedeño, Paloma; Campuzano, Susana; Pingarrón, José M.

2016-01-01

Ultrasensitive biosensing is currently a growing demand that has led to the development of numerous strategies for signal amplification. In this context, the unique properties of magnetic particles; both of nano- and micro-size dimensions; have proved to be promising materials to be coupled with disposable electrodes for the design of cost-effective electrochemical affinity biosensing platforms. This review addresses, through discussion of selected examples, the way that nano- and micro-magnetic particles (MNPs and MMPs; respectively) have contributed significantly to the development of electrochemical affinity biosensors, including immuno-, DNA, aptamer and other affinity modes. Different aspects such as type of magnetic particles, assay formats, detection techniques, sensitivity, applicability and other relevant characteristics are discussed. Research opportunities and future development trends in this field are also considered. PMID:27681733

Conducting Polymer 3D Microelectrodes

PubMed Central

Sasso, Luigi; Vazquez, Patricia; Vedarethinam, Indumathi; Castillo-León, Jaime; Emnéus, Jenny; Svendsen, Winnie E.

2010-01-01

Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared with electrodes coated with only metal. An electrochemical characterization of gold/polypyrrole electrodes showed exceptional electrochemical behavior and activity. PC12 cells were finally cultured on the investigated materials as a preliminary biocompatibility assessment. These results show that the described electrodes are possibly suitable for future in-vitro neurological measurements. PMID:22163508

Electrochemically-driven large amplitude pH cycling for acid-base driven DNA denaturation and renaturation.

PubMed

Wang, Yong-Chun; Lin, Cong-Bin; Su, Jian-Jia; Ru, Ying-Ming; Wu, Qiao; Chen, Zhao-Bin; Mao, Bing-Wei; Tian, Zhao-Wu

2011-06-15

In this paper, we present an electrochemically driven large amplitude pH alteration method based on a serial electrolytic cell involving a hydrogen permeable bifacial working electrode such as Pd thin foil. The method allows solution pH to be changed periodically up to ±4~5 units without additional alteration of concentration and/or composition of the system. Application to the acid-base driven cyclic denaturation and renaturation of 290 bp DNA fragments is successfully demonstrated with in situ real-time UV spectroscopic characterization. Electrophoretic analysis confirms that the denaturation and renaturation processes are reversible without degradation of the DNA. The serial electrolytic cell based electrochemical pH alteration method presented in this work would promote investigations of a wide variety of potential-dependent processes and techniques.

Electrodeposition synthesis and electrochemical properties of nanostructured γ-MnO 2 films

NASA Astrophysics Data System (ADS)

Chou, Shulei; Cheng, Fangyi; Chen, Jun

The thin films of carambola-like γ-MnO 2 nanoflakes with about 20 nm in thickness and at least 200 nm in width were prepared on nickel sheets by combination of potentiostatic and cyclic voltammetric electrodeposition techniques. The as-prepared MnO 2 nanomaterials, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were used as the active material of the positive electrode for primary alkaline Zn/MnO 2 batteries and electrochemical supercapacitors. Electrochemical measurements showed that the MnO 2 nanoflake films displayed high potential plateau (around 1.0 V versus Zn) in primary Zn/MnO 2 batteries at the discharge current density of 500 mA g -1 and high specific capacitance of 240 F g -1 at the current density of 1 mA cm -2. This indicated the potential application of carambola-like γ-MnO 2 nanoflakes in high-power batteries and electrochemical supercapacitors. The growth process for the one- and three-dimensional nanostructured MnO 2 was discussed on the basis of potentiostatic and cyclic voltammetric techniques. The present synthesis method can be extended to the preparation of other nanostructured metal-oxide films.

A review of fractional-order techniques applied to lithium-ion batteries, lead-acid batteries, and supercapacitors

NASA Astrophysics Data System (ADS)

Zou, Changfu; Zhang, Lei; Hu, Xiaosong; Wang, Zhenpo; Wik, Torsten; Pecht, Michael

2018-06-01

Electrochemical energy storage systems play an important role in diverse applications, such as electrified transportation and integration of renewable energy with the electrical grid. To facilitate model-based management for extracting full system potentials, proper mathematical models are imperative. Due to extra degrees of freedom brought by differentiation derivatives, fractional-order models may be able to better describe the dynamic behaviors of electrochemical systems. This paper provides a critical overview of fractional-order techniques for managing lithium-ion batteries, lead-acid batteries, and supercapacitors. Starting with the basic concepts and technical tools from fractional-order calculus, the modeling principles for these energy systems are presented by identifying disperse dynamic processes and using electrochemical impedance spectroscopy. Available battery/supercapacitor models are comprehensively reviewed, and the advantages of fractional types are discussed. Two case studies demonstrate the accuracy and computational efficiency of fractional-order models. These models offer 15-30% higher accuracy than their integer-order analogues, but have reasonable complexity. Consequently, fractional-order models can be good candidates for the development of advanced battery/supercapacitor management systems. Finally, the main technical challenges facing electrochemical energy storage system modeling, state estimation, and control in the fractional-order domain, as well as future research directions, are highlighted.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Sangmo; Paranthaman, Mariappan Parans; Noh, Tae Won

The voltage spectroscopies in scanning probe microscopy (SPM) techniques are widely used to investigate the electrochemical processes in nanoscale volumes, which are important for current key applications, such as batteries, fuel cells, catalysts, and memristors. The spectroscopic measurements are commonly performed on a grid of multiple points to yield spatially resolved maps of reversible and irreversible electrochemical functionalities. Hence, the spacing between measurement points is an important parameter to be considered, especially for irreversible electrochemical processes. Here, we report nonlocal electrochemical dynamics in chains of Ag particles fabricated by the SPM tip on a silver ion solid electrolyte. When themore » grid spacing is small compared with the size of the formed Ag particles, anomalous chains of unequally sized particles with double periodicity evolve. This behavior is ascribed to a proximity effect during the tip-induced electrochemical process, specifically, size-dependent silver particle growth following the contact between the particles. In addition, fractal shape evolution of the formed Ag structures indicates that the growth-limiting process changes from Ag +/Ag redox reaction to Ag +-ion diffusion with the increase in the applied voltage and pulse duration. Our study shows that characteristic shapes of the electrochemical products are good indicators for determining the underlying growth-limiting process, and emergence of complex phenomena during spectroscopic mapping of electrochemical functionalities.« less

Link between the dielectric properties of mesomorphic and biological materials

NASA Astrophysics Data System (ADS)

Szwajczak, Elzbieta; Szymanski, Aleksander B.

2002-06-01

An application of liquid crystalline materials as a model materials for the use in dielectric spectroscopy of the artificial biological materials and the tissues is discussed. It is shown that an application of the standard electrochemical concepts may break in the case of liquid crystalline materials as well as biological materials. The presence of space charge regions as well as electrical non- linearities of the sample may suggest some special possibility of the time domain technique application.

Creating new superconducting & semiconducting nanomaterials and investigating the effect of reduced dimensionality on their properties

NASA Astrophysics Data System (ADS)

Mishra, Sukhada

The field of nanomaterials has continued to attract researchers to understand the fundamentals and to investigate potential applications in the fields of semiconductor physics, microfabrication, nanomedicine, surface sciences etc. One of the most critical aspects of the nanomaterials research is to establish synthetic protocols, which can address the underlying product requirements of reproducibility, homogenous morphology and controlled elemental composition. We have focused our research in exploring synthetic routes for the synthesis of superconducting and semiconducting nanomaterials and analyze their structure---property relationship through detailed characterizations. The first part of dissertation is focused on the synthesis of superconducting FeSe nanostructures using catalyst assisted chemical vapor deposition (CVD) technique. The effect of catalyst---FeSe interphase on the d spacing of the FeSe nanostructures has been analyzed, and the internal pressure effect on the Tc has been investigated further through in depth characterizations. The emphasis of second part is on the development of a simple yet versatile protocol for the synthesis of vertically aligned nanorod arrays on conducting substrate by combining electron beam lithography technique with electrochemical deposition. The technique has been utilized to fabricate photovoltaic CdTe nanorod arrays on conducting substrate and further extended to devise CdS---CdTe nanorod arrays to create radial and lateral p---n junction assembly. Using photo---electrochemical analysis, it was observed that, the nanorod arrays yielded higher photo---electrochemical current compared to the thin film counterpart. The third part of dissertation describes the CVD protocol to synthesize multifunctional, dumbbell shaped Au---CoSe nanoparticles, which possess potential applications in ' theronostic' biological examinations.

Nanoparticle shape evolution and proximity effects during tip-induced electrochemical processes

DOE PAGES

Yang, Sangmo; Paranthaman, Mariappan Parans; Noh, Tae Won; ...

2016-01-08

The voltage spectroscopies in scanning probe microscopy (SPM) techniques are widely used to investigate the electrochemical processes in nanoscale volumes, which are important for current key applications, such as batteries, fuel cells, catalysts, and memristors. The spectroscopic measurements are commonly performed on a grid of multiple points to yield spatially resolved maps of reversible and irreversible electrochemical functionalities. Hence, the spacing between measurement points is an important parameter to be considered, especially for irreversible electrochemical processes. Here, we report nonlocal electrochemical dynamics in chains of Ag particles fabricated by the SPM tip on a silver ion solid electrolyte. When themore » grid spacing is small compared with the size of the formed Ag particles, anomalous chains of unequally sized particles with double periodicity evolve. This behavior is ascribed to a proximity effect during the tip-induced electrochemical process, specifically, size-dependent silver particle growth following the contact between the particles. In addition, fractal shape evolution of the formed Ag structures indicates that the growth-limiting process changes from Ag +/Ag redox reaction to Ag +-ion diffusion with the increase in the applied voltage and pulse duration. Our study shows that characteristic shapes of the electrochemical products are good indicators for determining the underlying growth-limiting process, and emergence of complex phenomena during spectroscopic mapping of electrochemical functionalities.« less

An impressive approach to solving the ongoing stability problems of LiCoPO4 cathode: Nickel oxide surface modification with excellent core-shell principle

NASA Astrophysics Data System (ADS)

Örnek, Ahmet

2017-07-01

Nanoscale and NiO-coated LiCoPO4 cathode materials were prepared for the first time by a newly designed three-step synthesis route, which is a combined technique including advantages of the Stöber, hydrothermal and microwave synthesis methods. Using this extraordinary technique, LiCoPO4 particles are coated with a thin NiO layer with a perfect core-shell morphology and the technique's positive contribution to electrochemistry is elucidated in detail. The samples are interpreted using opto-analytical techniques and galvanostatic charge-discharge tests. The high-resolution transmission electron microscopy analysis proves that this well-elaborated technique makes it possible to achieve a continuous NiO surface coverage of 8-10 nm, a result that contributes towards solving the chronic electrochemical problems of 4.8 V cathode material. Our data reveal that NiO-coated LiCoPO4 cathode demonstrates superior cycle stability and specific capacity at relatively low rates. The 2.5% wt. NiO-coated cathode exhibits the best electrochemical property, which reaches a discharge capacity of 159 mAh g-1 at 0.l C current rate and shows almost 85% capacity retention after 80 charge-discharge cycles. It therefore achieves partial success in improving the electrochemical properties of the LiCoPO4 cathode material, which is especially crucial for energy storage to be applied in electric vehicles and plug-in hybrid electric applications.

Microbiome involved in microbial electrochemical systems (MESs): A review.

PubMed

Saratale, Rijuta Ganesh; Saratale, Ganesh Dattatraya; Pugazhendhi, Arivalagan; Zhen, Guangyin; Kumar, Gopalakrishnan; Kadier, Abudukeremu; Sivagurunathan, Periyasamy

2017-06-01

Microbial electrochemical systems (MESs) are an attracting technology for the disposal of wastewater treatment and simultaneous energy production. In MESs, at the anode microorganisms through the catalytic activity generates electrons that can be converted into electricity or other valuable chemical compounds. Microorganisms those having ability to donate and accept electrons to and from anode and cathode electrodes, respectively are recognized as 'exoelectrogens'. In the MESs, it renders an important function for its performance. In the present mini-review, we have discussed the role of microbiome including pure culture, enriched culture and mixed culture in different BESs application. The effects of operational and biological factors on microbiome development have been discussed. Further discussion about the molecular techniques for the evaluation of microbial community analysis is addressed. In addition different electrochemical techniques for extracellular electron transfer (EET) mechanism of electroactive biofilms have been discussed. This review highlights the importance of microbiome in the development of MESs, effective operational factors for exo-electrogens activities as well their key challenges and future technological aspects are also briefly discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrochemical and photoelectrochemical nano-immunesensing using origami paper based method.

PubMed

Hasanzadeh, Mohammad; Shadjou, Nasrin

2016-04-01

Patterned paper has characteristics that lead to miniaturized assays that run by capillary action with small volumes of fluids. These methods suggest a path for the development of simple, inexpensive, and portable diagnostic assays that can be useful in remote settings, where simple immunoassays are becoming increasingly important for detecting disease and monitoring health. Incorporation of nanomaterials plays a major role in sensing probe immobilization and detection sensitivity of paper-based devices. Nanomaterial properties, such as increased surface area, have aided with signal amplification and lower detection limits. This review focuses on application of nanomaterials as signal amplification elements on origami paper-based electro-analytical devices for immune biomarkers detection with a brief introduction about various fabrication techniques and designs, biological and detection methods. In this review, we comprehensively summarize the selected latest research articles from 2013 to May 2015 on application of nanomaterials in various types of origami paper based electrochemical and photoelectrochemical immunosensors. The review breaks into two parts. The first part devotes to the development and applications of nanomaterials in electrochemical immunesensing. The second part provides an overview of recent origami paper based photoelectrochemical immunosensors. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrochemical monitoring of high-temperature molten-salt corrosion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, G.; Stott, F.H.; Dawson, J.L.

1990-02-01

Hot molten-salt corrosion can cause serious metal degradation in boiler plant, incinerators, and furnaces. In this research, electrochemical-impedance and electrochemical-noise techniques have been evaluated for the monitoring of hot-corrosion processes in such plants. Tests have been carried out on Ni-1% Co and Alloy 800, a commercial material of interest to operators of industrial plants. Electrochemical-impedance and electrochemical-noise data were compared with the results of metallographic examination of the test alloys and showed reasonable correlation between the electrochemical data and the actual degradation processes. This preliminary work indicated that the electrochemical techniques show considerable promise as instruments for the monitoring ofmore » high-temperature corrosion processes.« less

Synthesis of iron oxides nanoparticles with very high saturation magnetization form TEA-Fe(III) complex via electrochemical deposition for supercapacitor applications

NASA Astrophysics Data System (ADS)

Elrouby, Mahmoud; Abdel-Mawgoud, A. M.; El-Rahman, Rehab Abd

2017-11-01

This work is devoted to the synthesis of magnetic iron oxides nanoparticles with very high saturation magnetization to be qualified for supercapacitor applications using, a simple electrodeposition technique. It is found that the electrochemical reduction process depends on concentration, temperature, deposition potential and the scan rate of potential. The nature of electrodeposition process has been characterized via voltammetric and chronoamperometric techniques. The morphology of the electrodeposits has been investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure and phase content of these investigated electrodeposits have been examined and calculated. The obtained iron oxides show a high saturation magnetization (Ms) of about 229 emu g-1. The data exhibited a relation between Ms of electrodeposited iron oxide and specific capacitance. This relation exhibits that the highest Ms value of electrodeposited iron oxides gives also highest specific capacitance of about 725 Fg-1. Moreover, the electrodeposited iron oxides exhibit a very good stability. The new characteristics of the electro synthesized iron oxides at our optimized conditions, strongly qualify them as a valuable material for high-performance supercapacitor applications.

Electrochemical biosensors for hormone analyses.

PubMed

Bahadır, Elif Burcu; Sezgintürk, Mustafa Kemal

2015-06-15

Electrochemical biosensors have a unique place in determination of hormones due to simplicity, sensitivity, portability and ease of operation. Unlike chromatographic techniques, electrochemical techniques used do not require pre-treatment. Electrochemical biosensors are based on amperometric, potentiometric, impedimetric, and conductometric principle. Amperometric technique is a commonly used one. Although electrochemical biosensors offer a great selectivity and sensitivity for early clinical analysis, the poor reproducible results, difficult regeneration steps remain primary challenges to the commercialization of these biosensors. This review summarizes electrochemical (amperometric, potentiometric, impedimetric and conductometric) biosensors for hormone detection for the first time in the literature. After a brief description of the hormones, the immobilization steps and analytical performance of these biosensors are summarized. Linear ranges, LODs, reproducibilities, regenerations of developed biosensors are compared. Future outlooks in this area are also discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Investigation of novel zinc molybdate-graphene nanocomposite for supercapacitor applications

NASA Astrophysics Data System (ADS)

Reddy, B. Joji; Vickraman, P.; Justin, A. Simon

2018-06-01

Novel zinc molybdate-graphene nanocomposite is prepared for the first time in a fast, facile and eco-friendly microwave synthesis route as an electrode material for electrochemical supercapacitors. The as-prepared sample is investigated by X-ray diffraction, FTIR, Raman, scanning electron microscope and transmission electron microscope techniques. The studies have confirmed the formation of ZnMoO4 and its composite with graphene. The synthesized materials are subjected to electrochemical characterization studies in 2M KOH electrolyte solution which prove that ZnMoO4-graphene as an effective electrode material for supercapacitor applications. ZnMoO4 in its composite behavior has exhibited a specific capacitance of 272.93 F g- 1 at 0.5 A g- 1 with good cyclic stability for 1000 cycles.

Acoustic Liquid Manipulation Used to Enhance Electrochemical Processes

NASA Technical Reports Server (NTRS)

Oeftering, Richard C.

2005-01-01

Working in concert with the NASA Technology Transfer and Partnership Office, the Great Lakes Industrial Technology Center, and Alchemitron Corporation of Elgin, Illinois, the NASA Glenn Research Center has applied nonlinear acoustic principles to industrial applications. High-intensity ultrasonic beam techniques employ the effects of acoustic radiation pressure and acoustic streaming to manipulate the behavior of liquids. This includes propelling liquids, moving bubbles, and ejecting liquids as droplets and fountains. Since these effects can be accomplished without mechanical pumps or moving parts, we are exploring how these techniques could be used to manipulate liquids in space applications. Some of these acoustic techniques could be used both in normal Earth gravity and in the microgravity of space.

Electrophoretically deposited reduced graphene oxide platform for food toxin detection

NASA Astrophysics Data System (ADS)

Srivastava, Saurabh; Kumar, Vinod; Ali, Md Azahar; Solanki, Pratima R.; Srivastava, Anchal; Sumana, Gajjala; Saxena, Preeti Suman; Joshi, Amish G.; Malhotra, B. D.

2013-03-01

Reduced graphene oxide (RGO) due to its excellent electrochemical properties and large surface area, has recently aroused much interest for electrochemical biosensing application. Here, the chemically active RGO has been synthesized and deposited onto an indium tin oxide (ITO) coated glass substrate by the electrophoretic deposition technique. This novel platform has been utilized for covalent attachment of the monoclonal antibodies of aflatoxin B1 (anti-AFB1) for food toxin (AFB1) detection. The electron microscopy, X-ray diffraction, and UV-visible studies reveal successful synthesis of reduced graphene oxide while the XPS and FTIR studies suggest its carboxylic functionalized nature. The electrochemical sensing results of the anti-AFB1/RGO/ITO based immunoelectrode obtained as a function of aflatoxin concentration show high sensitivity (68 μA ng-1 mL cm-2) and improved detection limit (0.12 ng mL-1). The association constant (ka) for antigen-antibody interaction obtained as 5 × 10-4 ng mL-1 indicates high affinity of antibodies toward the antigen (AFB1).Reduced graphene oxide (RGO) due to its excellent electrochemical properties and large surface area, has recently aroused much interest for electrochemical biosensing application. Here, the chemically active RGO has been synthesized and deposited onto an indium tin oxide (ITO) coated glass substrate by the electrophoretic deposition technique. This novel platform has been utilized for covalent attachment of the monoclonal antibodies of aflatoxin B1 (anti-AFB1) for food toxin (AFB1) detection. The electron microscopy, X-ray diffraction, and UV-visible studies reveal successful synthesis of reduced graphene oxide while the XPS and FTIR studies suggest its carboxylic functionalized nature. The electrochemical sensing results of the anti-AFB1/RGO/ITO based immunoelectrode obtained as a function of aflatoxin concentration show high sensitivity (68 μA ng-1 mL cm-2) and improved detection limit (0.12 ng mL-1). The association constant (ka) for antigen-antibody interaction obtained as 5 × 10-4 ng mL-1 indicates high affinity of antibodies toward the antigen (AFB1). Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr32242d

An electrochemical sensing approach for scouting microbial chemolithotrophic metabolisms.

PubMed

Saavedra, Albert; Figueredo, Federico; Cortón, Eduardo; Abrevaya, Ximena C

2018-05-01

The present study was aimed to test an electrochemical sensing approach for the detection of an active chemolithotrophic metabolism (and therefore the presence of chemolithotrophic microorganisms) by using the corrosion of pyrite by Acidithiobacillus ferrooxidans as a model. Different electrochemical techniques were combined with adhesion studies and scanning electron microscopy (SEM). The experiments were performed in presence or absence of A. ferrooxidans and without or with ferrous iron in the culture medium (0 and 0.5 g L -1 , respectively). Electrochemical parameters were in agreement with voltammetric studies and SEM showing that it is possible to distinguish between an abiotically-induced corrosion process (AIC) and a microbiologically-induced corrosion process (MIC). The results show that our approach not only allows the detection of chemolithotrophic activity of A. ferrooxidans but also can characterize the corrosion process. This may have different kind of applications, from those related to biomining to life searching missions in other planetary bodies. Copyright © 2018 Elsevier B.V. All rights reserved.

Sol-gel Technology and Advanced Electrochemical Energy Storage Materials

NASA Technical Reports Server (NTRS)

Chu, Chung-tse; Zheng, Haixing

1996-01-01

Advanced materials play an important role in the development of electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. The sol-gel process is a versatile solution for use in the fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. This processing technique is particularly useful in producing porous materials with high surface area and low density, two of the most desirable characteristics for electrode materials. In addition,the porous surface of gels can be modified chemically to create tailored surface properties, and inorganic/organic micro-composites can be prepared for improved material performance device fabrication. Applications of several sol-gel derived electrode materials in different energy storage devices are illustrated in this paper. V2O5 gels are shown to be a promising cathode material for solid state lithium batteries. Carbon aerogels, amorphous RuO2 gels and sol-gel derived hafnium compounds have been studied as electrode materials for high energy density and high power density electrochemical capacitors.

High voltage electrophoretic deposition for electrochemical energy storage and other applications

NASA Astrophysics Data System (ADS)

Santhanagopalan, Sunand

High voltage electrophoretic deposition (HVEPD) has been developed as a novel technique to obtain vertically aligned forests of one-dimensional nanomaterials for efficient energy storage. The ability to control and manipulate nanomaterials is critical for their effective usage in a variety of applications. Oriented structures of one-dimensional nanomaterials provide a unique opportunity to take full advantage of their excellent mechanical and electrochemical properties. However, it is still a significant challenge to obtain such oriented structures with great process flexibility, ease of processing under mild conditions and the capability to scale up, especially in context of efficient device fabrication and system packaging. This work presents HVEPD as a simple, versatile and generic technique to obtain vertically aligned forests of different one-dimensional nanomaterials on flexible, transparent and scalable substrates. Improvements on material chemistry and reduction of contact resistance have enabled the fabrication of high power supercapacitor electrodes using the HVEPD method. The investigations have also paved the way for further enhancements of performance by employing hybrid material systems and AC/DC pulsed deposition. Multi-walled carbon nanotubes (MWCNTs) were used as the starting material to demonstrate the HVEPD technique. A comprehensive study of the key parameters was conducted to better understand the working mechanism of the HVEPD process. It has been confirmed that HVEPD was enabled by three key factors: high deposition voltage for alignment, low dispersion concentration to avoid aggregation and simultaneous formation of holding layer by electrodeposition for reinforcement of nanoforests. A set of suitable parameters were found to obtain vertically aligned forests of MWCNTs. Compared with their randomly oriented counterparts, the aligned MWCNT forests showed better electrochemical performance, lower electrical resistance and a capability to achieve superhydrophpbicity, indicating their potential in a broad range of applications. The versatile and generic nature of the HVEPD process has been demonstrated by achieving deposition on flexible and transparent substrates, as well as aligned forests of manganese dioxide (MnO2) nanorods. A continuous roll-printing HVEPD approach was then developed to obtain aligned MWCNT forest with low contact resistance on large, flexible substrates. Such large-scale electrodes showed no deterioration in electrochemical performance and paved the way for practical device fabrication. The effect of a holding layer on the contact resistance between aligned MWCNT forests and the substrate was studied to improve electrochemical performance of such electrodes. It was found that a suitable precursor salt like nickel chloride could be used to achieve a conductive holding layer which helped to significantly reduce the contact resistance. This in turn enhanced the electrochemical performance of the electrodes. High-power scalable redox capacitors were then prepared using HVEPD. Very high power/energy densities and excellent cyclability have been achieved by synergistically combining hydrothermally synthesized, highly crystalline α-MnO 2 nanorods, vertically aligned forests and reduced contact resistance. To further improve the performance, hybrid electrodes have been prepared in the form of vertically aligned forest of MWCNTs with branches of α-MnO 2 nanorods on them. Large- scale electrodes with such hybrid structures were manufactured using continuous HVEPD and characterized, showing further improved power and energy densities. The alignment quality and density of MWCNT forests were also improved by using an AC/DC pulsed deposition technique. In this case, AC voltage was first used to align the MWCNTs, followed by immediate DC voltage to deposit the aligned MWCNTs along with the conductive holding layer. Decoupling of alignment from deposition was proven to result in better alignment quality and higher electrochemical performance.

Rapid, quantitative and sensitive immunochromatographic assay based on stripping voltammetric detection of a metal ion label

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Fang; Wang, Kaihua; Lin, Yuehe

2005-10-10

A novel, sensitive immunochromatographic electrochemical biosensor (IEB) which combines an immunochromatographic strip technique with an electrochemical detection technique is demonstrated. The IEB takes advantages of the speed and low-cost of the conventional immunochromatographic test kits and high-sensitivity of stripping voltammetry. Bismuth ions (Bi3+) have been coupled with the antibody through the bifunctional chelating agent diethylenetriamine pentaacetic acid (DTPA). After immunoreactions, Bi3+ was released and quantified by anodic stripping voltammetry at a built-in single-use screen-printed electrode. As an example for the applications of such novel device, the detection of human chorionic gonadotronphin (HCG) in a specimen was performed. This biosensor providesmore » a more user-friendly, rapid, clinically accurate, and less expensive immunoassay for such analysis in specimens than currently available test kits.« less

Significant enhancement in volumetric and gravimetric capacitance of Cu-TiO2/PPY composite for supercapacitor application

NASA Astrophysics Data System (ADS)

Purty, B.; Choudhary, R. B.

2018-04-01

Copper doped titanium dioxide-polypyrrole (Cu-TiO2/PPY) composite was successfully synthesized via chemical oxidative in-situ polymerization process. The structural and morphological properties of Cu-TiO2/PPY composite were investigated using X-ray diffractometer (XRD), field emission electron microscopy (FESEM) and transmission electron microscopy(TEM) techniques. The electrochemical properties of as-synthesized composite were studied using cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopic (EIS) techniques. The novel Cu-TiO2/PPY composite showed enhanced volumetric capacitance ˜714 F cm-1 and gravimetric capacitance ˜674 F g-1 at 1 A g-1. In addition an excellent coulombic efficiency and comparabley low charge transfer resistance than pure PPY suggests improved supercapacitive performance of Cu-TiO2/PPY composite as an electrode material.

Energy conversion and storage program

NASA Astrophysics Data System (ADS)

Cairns, E. J.

1992-03-01

The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: (1) production of new synthetic fuels; (2) development of high-performance rechargeable batteries and fuel cells; (3) development of advanced thermochemical processes for energy conversion; (4) characterization of complex chemical processes; and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

The Current Status of Hydrogen Storage Alloy Development for Electrochemical Applications.

PubMed

Young, Kwo-Hsiung; Nei, Jean

2013-10-17

In this review article, the fundamentals of electrochemical reactions involving metal hydrides are explained, followed by a report of recent progress in hydrogen storage alloys for electrochemical applications. The status of various alloy systems, including AB₅, AB₂, A₂B₇-type, Ti-Ni-based, Mg-Ni-based, BCC, and Zr-Ni-based metal hydride alloys, for their most important electrochemical application, the nickel metal hydride battery, is summarized. Other electrochemical applications, such as Ni-hydrogen, fuel cell, Li-ion battery, air-metal hydride, and hybrid battery systems, also have been mentioned.

Electrical impedance spectroscopy for quality assessment of meat and fish: A review on basic principles, measurement methods, and recent advances

USDA-ARS?s Scientific Manuscript database

Electrical impedance spectroscopy (EIS), as an effective analytical technique for electrochemical system, has shown a wide application for food quality and safety assessment recently. Individual differences of livestock cause high variation in quality of raw meat and fish and their commercialized pr...

To study the effect of different electrolytes and their concentrations on electrochemical micromachining

NASA Astrophysics Data System (ADS)

Singh, Ramandeep

2018-04-01

The machining of materials on micro-meter and sub-micrometre is considered the technology of future. Due to challenging applications of biomedical and aerospace industries, the traditional manufacturing techniques lacks in dimensional accuracy. Thus for such industries, the technique that can control micron tolerances is Electrochemical Micromachining (EMM). Hard metals and alloys can also be machined by this technique. Thus to develop a novel EMM system setup and to investigate the effect of three different electrolytes i.e NaCl, NaNO3 and HCl with their different concentrations, the current study was conducted. Stainless Steel-304 and copper were chosen as the work piece material in the present study. Taguchi L18 orthogonal array was used for the best combination of experiment. According to the present investigation most prominent factor affecting the material removal (MR) comes out was electrolyte. HCl provides the better MR among other electrolytes i.e. NaNO3 and NaCl. The amount of MR increased with the increase in the concentration of electrolyte.

Simultaneous Voltammetric Detection of Carbaryl and Paraquat Pesticides on Graphene-Modified Boron-Doped Diamond Electrode

PubMed Central

Pop, Aniela; Manea, Florica; Flueras, Adriana; Schoonman, Joop

2017-01-01

Monitoring of pesticide residues in food, beverages, and the environment requires fast, versatile, and sensitive analyzing methods. Direct electrochemical detection of pesticides could represent an efficient solution. Adequate electrode material, electrochemical technique, and optimal operation parameters define the detection method for practical application. In this study, cyclic voltammetric and differential pulse voltammetric techniques were used in order to individually and simultaneously detect two pesticides, i.e., carbaryl (CR) and paraquat (PQ), from an acetate buffer solution and also from natural apple juice. A graphene-modified boron-doped diamond electrode, denoted BDDGR, was obtained and successfully applied in the simultaneous detection of CR and PQ pesticides, using the differential pulse voltammetric technique with remarkable electroanalytical parameters in terms of sensitivity: 33.27 μA μM−1 cm−2 for CR and 31.83 μA μM−1 cm−2 for PQ. These outstanding results obtained in the acetate buffer supporting electrolyte allowed us to simultaneously detect the targeted pesticides in natural apple juice. PMID:28878151

Probing the chemistry of nickel/metal hydride battery cells using electrochemical impedance spectroscopy

NASA Technical Reports Server (NTRS)

Isaac, Bryan J.

1994-01-01

Electrochemical Impedance Spectroscopy (EIS) is a valuable tool for investigating the chemical and physical processes occurring at electrode surfaces. It offers information about electron transfer at interfaces, kinetics of reactions, and diffusion characteristics of the bulk phase between the electrodes. For battery cells, this technique offers another advantage in that it can be done without taking the battery apart. This non-destructive analysis technique can thus be used to gain a better understanding of the processes occurring within a battery cell. This also raises the possibility of improvements in battery design and identification or prediction of battery characteristics useful in industry and aerospace applications. EIS as a technique is powerful and capable of yielding significant information about the cell, but it also requires that the many parameters under investigation can be resolved. This implies an understanding of the processes occurring in a battery cell. Many battery types were surveyed in this work, but the main emphasis was on nickel/metal hydride batteries.

Electrochemical techniques on sequence-specific PCR amplicon detection for point-of-care applications.

PubMed

Luo, Xiaoteng; Hsing, I-Ming

2009-10-01

Nucleic acid based analysis provides accurate differentiation among closely affiliated species and this species- and sequence-specific detection technique would be particularly useful for point-of-care (POC) testing for prevention and early detection of highly infectious and damaging diseases. Electrochemical (EC) detection and polymerase chain reaction (PCR) are two indispensable steps, in our view, in a nucleic acid based point-of-care testing device as the former, in comparison with the fluorescence counterpart, provides inherent advantages of detection sensitivity, device miniaturization and operation simplicity, and the latter offers an effective way to boost the amount of targets to a detectable quantity. In this mini-review, we will highlight some of the interesting investigations using the combined EC detection and PCR amplification approaches for end-point detection and real-time monitoring. The promise of current approaches and the direction for future investigations will be discussed. It would be our view that the synergistic effect of the combined EC-PCR steps in a portable device provides a promising detection technology platform that will be ready for point-of-care applications in the near future.

Polypyrrole-coated samarium oxide nanobelts: fabrication, characterization, and application in supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Peng; Wang, Yunjiao; Wang, Xue; Yang, Chao; Yi, Yanfeng

2012-11-01

Polypyrrole-coated samarium oxide nanobelts were synthesized by the in situ chemical oxidative surface polymerization technique based on the self-assembly of pyrrole on the surface of the amine-functionalized Sm2O3 nanobelts. The morphologies of the polypyrrole/samarium oxide (PPy/Sm2O3) nanocomposites were characterized using transmission electron microscope. The UV-vis absorbance of these samples was also investigated, and the remarkable enhancement was clearly observed. The electrochemical behaviors of the PPy/Sm2O3 composites were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The results indicated that the PPy/Sm2O3 composite electrode was fully reversible and achieved a very fast Faradaic reaction. After being corrected into the weight percentage of the PPy/Sm2O3 composite at a current density of 20 mA cm-2 in a 1.0 M NaNO3 electrolyte solution, a maximum discharge capacity of 771 F g-1 was achieved in a half-cell setup configuration for the PPy/Sm2O3 composites electrode with the potential application to electrode materials for electrochemical capacitors.

The pH Response and Sensing Mechanism of n-Type ZnO/Electrolyte Interfaces

PubMed Central

Al-Hilli, Safaa; Willander, Magnus

2009-01-01

Ever since the discovery of the pH-sensing properties of ZnO crystals, researchers have been exploring their potential in electrochemical applications. The recent expansion and availability of chemical modification methods has made it possible to generate a new class of electrochemically active ZnO nanorods. This reduction in size of ZnO (to a nanocrystalline form) using new growth techniques is essentially an example of the nanotechnology fabrication principle. The availability of these ZnO nanorods opens up an entire new and exciting research direction in the field of electrochemical sensing. This review covers the latest advances and mechanism of pH-sensing using ZnO nanorods, with an emphasis on the nano-interface mechanism. We discuss methods for calculating the effect of surface states on pH-sensing at a ZnO/electrolyte interface. All of these current research topics aim to explain the mechanism of pH-sensing using a ZnO bulk- or nano-scale single crystal. An important goal of these investigations is the translation of these nanotechnology-modified nanorods into potential novel applications. PMID:22423211

Problems, pitfalls and probes: Welcome to the jungle of electrochemical noise technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edgemon, G.L.

1998-02-19

The rise in electrochemical noise (EN) as a corrosion monitoring technique has resulted in unique problems associated with the field application of this method. Many issues relate to the design of the EN probe electrodes. The ability of an electrochemical noise monitoring system to identify and discriminate between localized corrosion mechanisms is related primarily to the capability of the probe to separate the corrosion cell anode from the corresponding cathode. Effectiveness of this separation is largely determined by the details of and the proper design of the probe that is in the environment of interest. No single probe design ormore » geometry can be effectively use in every situation to monitor all types of corrosion. In this paper the authors focus on a case study and probe development history related to monitoring corrosion in an extremely hostile environment using EN. While the ultimate application of EN was and continues to be successful, the case study shows that patience and persistence was necessary to meet and properly implement the monitoring program. Other possible source of problems and frustration with implementing EN are also discussed.« less

The pH Response and Sensing Mechanism of n-Type ZnO/Electrolyte Interfaces.

PubMed

Al-Hilli, Safaa; Willander, Magnus

2009-01-01

Ever since the discovery of the pH-sensing properties of ZnO crystals, researchers have been exploring their potential in electrochemical applications. The recent expansion and availability of chemical modification methods has made it possible to generate a new class of electrochemically active ZnO nanorods. This reduction in size of ZnO (to a nanocrystalline form) using new growth techniques is essentially an example of the nanotechnology fabrication principle. The availability of these ZnO nanorods opens up an entire new and exciting research direction in the field of electrochemical sensing. This review covers the latest advances and mechanism of pH-sensing using ZnO nanorods, with an emphasis on the nano-interface mechanism. We discuss methods for calculating the effect of surface states on pH-sensing at a ZnO/electrolyte interface. All of these current research topics aim to explain the mechanism of pH-sensing using a ZnO bulk- or nano-scale single crystal. An important goal of these investigations is the translation of these nanotechnology-modified nanorods into potential novel applications.

Fabrication of free-standing, electrochemically active, and biocompatible graphene oxide-polyaniline and graphene-polyaniline hybrid papers.

PubMed

Yan, Xingbin; Chen, Jiangtao; Yang, Jie; Xue, Qunji; Miele, Philippe

2010-09-01

In this work, we report a low-cost technique via simple rapid-mixture polymerization of aniline using graphene oxide (GO) and graphene papers as substrates, respectively, to fabricate free-standing, flexible GO-polyaniline (PANI) and graphene-PANI hybrid papers. The morphology and microstructure of the obtained papers were characterized by FESEM, FTIR, Raman, and XRD. As results, nanostructural PANI can be deposited on the surfaces of GO and graphene papers, forming thin, lightweight, and flexible paperlike hybrid papers. The hybrid papers display a remarkable combination of excellent electrochemical performances and biocompatibility, making the paperlike materials attractive for new kinds of applications in biosciences.

Improving cycle life of layered lithium transition metal oxide (LiMO2) based positive electrodes for Li ion batteries by smart selection of the electrochemical charge conditions

NASA Astrophysics Data System (ADS)

Kasnatscheew, Johannes; Evertz, Marco; Streipert, Benjamin; Wagner, Ralf; Nowak, Sascha; Cekic Laskovic, Isidora; Winter, Martin

2017-08-01

Increasing the specific energy of a lithium ion battery and maintaining its cycle life is a predominant goal and major challenge for electrochemical energy storage applications. Focusing on the positive electrode as the specific energy bottleneck, cycle life characteristics of promising layered oxide type active materials (LiMO2) has been thoroughly investigated. Comparing the variety of LiMO2 compositions, it could be shown that the "Ni-rich" (Ni ≥ 60% for M in LiMO2) electrodes expectably revealed best performance compromises between specific energy and cycle life at 20 °C, but only LiNi0.6Mn0.2Co0.2O2 (NMC622) could also maintain sufficient cycle performance at elevated temperatures. Focusing on NMC622, it could be demonstrated that the applied electrochemical conditions (charge capacity, delithiation amount) in the formation cycles significantly influence the subsequent cycling performance. Moreover, the insignificant transition metal dissolution, demonstrated by means of total X-ray fluorescence (TXRF) technique, and unchanged lithiation degree in the discharged state, determined by the measurement of the Li+ content by means of the inductively coupled plasma optical emission spectroscopy (ICP-OES) technique, pointed to a delithiation (charge) hindrance capacity fade mechanism. Considering these insights, thoughtful modifications of the electrochemical charge conditions could significantly prolong the cycle life.

Sensitive detection of pyoverdine with an electrochemical sensor based on electrochemically generated graphene functionalized with gold nanoparticles.

PubMed

Gandouzi, Islem; Tertis, Mihaela; Cernat, Andreea; Bakhrouf, Amina; Coros, Maria; Pruneanu, Stela; Cristea, Cecilia

2018-04-01

The design and development of an electrochemical sensor for the sensitive and selective determination of pyoverdine, a virulence factor secreted by Pseudomonas aeruginosa, bacteria involved in nosocomial infections is presented in this work. The presence of pyoverdine in water and body fluids samples can be directly linked to the presence of the Pseudomonas bacteria, thus being a nontoxic and low cost marker for the detection of water pollution as well as for the biological contamination of other media. The sensor was elaborated using layer-by-layer technique for the deposition of a graphene‑gold nanoparticles composite film on the graphite-based screen printed electrode, from aqueous suspension. Under optimal conditions, the electrochemical signal corresponding to the pyoverdine oxidation process was proportional to its concentration, showing a wide linear range from 1 to 100μmolL -1 and a detection limit of 0.33μmolL -1 . This sensor discriminate with satisfactory recoveries the target analyte in different real matrices and also exhibited low response to other interfering species, proving that this technique is promising for medical and environmental applications. In addition, the proposed nanocomposite platform presented good reproducibility, high and long term stability, the sensitivity for pyoverdine remain unchanged after being stored at 4°C for four weeks. Copyright © 2017 Elsevier B.V. All rights reserved.

Real-time, multiplexed electrochemical DNA detection using an active complementary metal-oxide-semiconductor biosensor array with integrated sensor electronics.

PubMed

Levine, Peter M; Gong, Ping; Levicky, Rastislav; Shepard, Kenneth L

2009-03-15

Optical biosensing based on fluorescence detection has arguably become the standard technique for quantifying extents of hybridization between surface-immobilized probes and fluorophore-labeled analyte targets in DNA microarrays. However, electrochemical detection techniques are emerging which could eliminate the need for physically bulky optical instrumentation, enabling the design of portable devices for point-of-care applications. Unlike fluorescence detection, which can function well using a passive substrate (one without integrated electronics), multiplexed electrochemical detection requires an electronically active substrate to analyze each array site and benefits from the addition of integrated electronic instrumentation to further reduce platform size and eliminate the electromagnetic interference that can result from bringing non-amplified signals off chip. We report on an active electrochemical biosensor array, constructed with a standard complementary metal-oxide-semiconductor (CMOS) technology, to perform quantitative DNA hybridization detection on chip using targets conjugated with ferrocene redox labels. A 4 x 4 array of gold working electrodes and integrated potentiostat electronics, consisting of control amplifiers and current-input analog-to-digital converters, on a custom-designed 5 mm x 3 mm CMOS chip drive redox reactions using cyclic voltammetry, sense DNA binding, and transmit digital data off chip for analysis. We demonstrate multiplexed and specific detection of DNA targets as well as real-time monitoring of hybridization, a task that is difficult, if not impossible, with traditional fluorescence-based microarrays.

Operando Soft X-ray Absorption Spectroscopic Study on a Solid Oxide Fuel Cell Cathode during Electrochemical Oxygen Reduction.

PubMed

Nakamura, Takashi; Oike, Ryo; Kimura, Yuta; Tamenori, Yusuke; Kawada, Tatsuya; Amezawa, Koji

2017-05-09

An operando soft X-ray absorption spectroscopic technique, which enabled the analysis of the electronic structures of the electrode materials at elevated temperature in a controlled atmosphere and electrochemical polarization, was established and its availability was demonstrated by investigating the electronic structural changes of an La 2 NiO 4+δ dense-film electrode during an electrochemical oxygen reduction reaction. Clear O K-edge and Ni L-edge X-ray absorption spectra could be obtained below 773 K under an atmospheric pressure of 100 ppm O 2 /He, 0.1 % O 2 /He, and 1 % O 2 /He gas mixtures. Considerable spectral changes were observed in the O K-edge X-ray absorption spectra upon changing the PO2 and application of electrical potential, whereas only small spectral changes were observed in Ni L-edge X-ray absorption spectra. A pre-edge peak of the O K-edge X-ray absorption spectra, which reflects the unoccupied partial density of states of Ni 3d-O 2p hybridization, increased or decreased with cathodic or anodic polarization, respectively. The electronic structural changes of the outermost orbital of the electrode material due to electrochemical polarization were successfully confirmed by the operando X-ray absorption spectroscopic technique developed in this study. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Current Status of Hydrogen Storage Alloy Development for Electrochemical Applications

PubMed Central

Young, Kwo-hsiung; Nei, Jean

2013-01-01

In this review article, the fundamentals of electrochemical reactions involving metal hydrides are explained, followed by a report of recent progress in hydrogen storage alloys for electrochemical applications. The status of various alloy systems, including AB5, AB2, A2B7-type, Ti-Ni-based, Mg-Ni-based, BCC, and Zr-Ni-based metal hydride alloys, for their most important electrochemical application, the nickel metal hydride battery, is summarized. Other electrochemical applications, such as Ni-hydrogen, fuel cell, Li-ion battery, air-metal hydride, and hybrid battery systems, also have been mentioned. PMID:28788349

Vertically aligned single-walled carbon nanotubes by chemical assembly--methodology, properties, and applications.

PubMed

Diao, Peng; Liu, Zhongfan

2010-04-06

Single-walled carbon nanotubes (SWNTs), as one of the most promising one-dimension nanomaterials due to its unique structure, peculiar chemical, mechanical, thermal, and electronic properties, have long been considered as an important building block to construct ordered alignments. Vertically aligned SWNTs (v-SWNTs) have been successfully prepared by using direct growth and chemical assembly strategies. In this review, we focus explicitly on the v-SWNTs fabricated via chemical assembly strategy. We provide the readers with a full and systematic summary covering the advances in all aspects of this area, including various approaches for the preparation of v-SWNTs using chemical assembly techniques, characterization, assembly kinetics, and electrochemical properties of v-SWNTs. We also review the applications of v-SWNTs in electrochemical and bioelectrochemical sensors, photoelectric conversion, and scanning probe microscopy.

A review on various electrochemical techniques for heavy metal ions detection with different sensing platforms.

PubMed

Bansod, BabanKumar; Kumar, Tejinder; Thakur, Ritula; Rana, Shakshi; Singh, Inderbir

2017-08-15

Heavy metal ions are non-biodegradable and contaminate most of the natural resources occurring in the environment including water. Some of the heavy metals including Lead (Pb), Mercury (Hg), Arsenic (As), Chromium (Cr) and Cadmium (Cd) are considered to be highly toxic and hazardous to human health even at trace levels. This leads to the requirement of fast, accurate and reliable techniques for the detection of heavy metal ions. This review presents various electrochemical detection techniques for heavy metal ions those are user friendly, low cost, provides on-site and real time monitoring as compared to other spectroscopic and optical techniques. The categorization of different electrochemical techniques is done on the basis of different types of detection signals generated due to presence of heavy metal ions in the solution matrix like current, potential, conductivity, electrochemical impedance, and electrochemiluminescence. Also, the recent trends in electrochemical detection of heavy metal ions with various types of sensing platforms including metals, metal films, metal oxides, nanomaterials, carbon nano tubes, polymers, microspheres and biomaterials have been evoked. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochemical monitoring of biointeraction by graphene-based material modified pencil graphite electrode.

PubMed

Eksin, Ece; Zor, Erhan; Erdem, Arzum; Bingol, Haluk

2017-06-15

Recently, the low-cost effective biosensing systems based on advanced nanomaterials have received a key attention for development of novel assays for rapid and sequence-specific nucleic acid detection. The electrochemical biosensor based on reduced graphene oxide (rGO) modified disposable pencil graphite electrodes (PGEs) were developed herein for electrochemical monitoring of DNA, and also for monitoring of biointeraction occurred between anticancer drug, Daunorubicin (DNR), and DNA. First, rGO was synthesized chemically and characterized by using UV-Vis, TGA, FT-IR, Raman Spectroscopy and SEM techniques. Then, the quantity of rGO assembling onto the surface of PGE by passive adsorption was optimized. The electrochemical behavior of rGO-PGEs was examined by cyclic voltammetry (CV). rGO-PGEs were then utilized for electrochemical monitoring of surface-confined interaction between DNR and DNA using differential pulse voltammetry (DPV) technique. Additionally, voltammetric results were complemented with electrochemical impedance spectroscopy (EIS) technique. Electrochemical monitoring of DNR and DNA was resulted with satisfying detection limits 0.55µM and 2.71µg/mL, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Real-Time Evaluation of Live Cancer Cells by an in Situ Surface Plasmon Resonance and Electrochemical Study.

PubMed

Wu, Changyu; Rehman, Fawad Ur; Li, Jingyuan; Ye, Jing; Zhang, Yuanyuan; Su, Meina; Jiang, Hui; Wang, Xuemei

2015-11-11

This work presents a new strategy of the combination of surface plasmon resonance (SPR) and electrochemical study for real-time evaluation of live cancer cells treated with daunorubicin (DNR) at the interface of the SPR chip and living cancer cells. The observations demonstrate that the SPR signal changes could be closely related to the morphology and mass changes of adsorbed cancer cells and the variation of the refractive index of the medium solution. The results of light microscopy images and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide studies also illustrate the release or desorption of HepG2 cancer cells, which were due to their apoptosis after treatment with DNR. It is evident that the extracellular concentration of DNR residue can be readily determined through electrochemical measurements. The decreases in the magnitudes of SPR signals were linearly related to cell survival rates, and the combination of SPR with electrochemical study could be utilized to evaluate the potential therapeutic efficiency of bioactive agents to cells. Thus, this label-free, real-time SPR-electrochemical detection technique has great promise in bioanalysis or monitoring of relevant treatment processes in clinical applications.

Real-Time Optical Monitoring of Pt Catalyst Under the Potentiodynamic Conditions

NASA Astrophysics Data System (ADS)

Song, Hyeon Don; Lee, Minzae; Kim, Gil-Pyo; Choi, Inhee; Yi, Jongheop

2016-12-01

In situ monitoring of electrode materials reveals detailed physicochemical transition in electrochemical device. The key challenge is to explore the localized features of electrode surfaces, since the performance of an electrochemical device is determined by the summation of local architecture of the electrode material. Adaptive in situ techniques have been developed for numerous investigations; however, they require restricted measurement environments and provide limited information, which has impeded their widespread application. In this study, we realised an optics-based electrochemical in situ monitoring system by combining a dark-field micro/spectroscopy with an electrochemical workstation to investigate the physicochemical behaviours of Pt catalyst. We found that the localized plasmonic trait of a Pt-decorated Au nanoparticle as a model system varied in terms of its intensity and wavelength during the iterations of a cyclic voltammetry test. Furthermore, we show that morphological and compositional changes of the Pt catalyst can be traced in real time using changes in quantified plasmonic characteristics, which is a distinct advantage over the conventional electrochemistry-based in situ monitoring systems. These results indicate the substantial promise of online operando observation in a wide range of electrical energy conversion systems and electrochemical sensing areas.

Hydrothermal synthesis of PEDOT/rGO composite for supercapacitor applications

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Rafat, M.

2018-01-01

In this study, PEDOT/rGO composite has been successfully synthesized using hydrothermal method. Precursor solution of EDOT monomer was mixed with a predetermined solution of graphene oxide (GO). The resultant mixture was then hydrothermally treated. Surface morphology, crystal structure vibrational response and thermal stability have been studied using standard characterization techniques: field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and thermo-gravimetric analysis. The observed results confirm that the required composite of PEDOT/rGO has indeed been synthesized. Electrochemical properties of the synthesized product were studied in 6 M KOH aqueous solution, using characterization techniques such as: cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge measurements. The results show a high value of specific capacitance (102.8 F g-1) at 10 mV s-1, indicating that the composite can be profitably used for energy storage devices.

A 0.18 μm biosensor front-end based on 1/f noise, distortion cancelation and chopper stabilization techniques.

PubMed

Balasubramanian, Viswanathan; Ruedi, Pierre-Francois; Temiz, Yuksel; Ferretti, Anna; Guiducci, Carlotta; Enz

2013-10-01

This paper presents a novel sensor front-end circuit that addresses the issues of 1/f noise and distortion in a unique way by using canceling techniques. The proposed front-end is a fully differential transimpedance amplifier (TIA) targeted for current mode electrochemical biosensing applications. In this paper, we discuss the architecture of this canceling based front-end and the optimization methods followed for achieving low noise, low distortion performance at minimum current consumption are presented. To validate the employed canceling based front-end, it has been realized in a 0.18 μm CMOS process and the characterization results are presented. The front-end has also been tested as part of a complete wireless sensing system and the cyclic voltammetry (CV) test results from electrochemical sensors are provided. Overall current consumption in the front-end is 50 μA while operating on a 1.8 V supply.

Investigation of temperature and concentration oscillations in the directional solidification of Pb-Sn-Te

NASA Technical Reports Server (NTRS)

Anderson, T. J.; Narayanan, R.

1987-01-01

Directional solidification of the pseudobinary compound semiconductor material Pb sub 1-x Sn sub x Te by the Bridgman crystal growth process will be studied. Natural convection in the molten sample will be visualized with a novel electrochemical cell technique that employs the solid electrolyte material yttria-stabilized zirconia. Mass transfer by both diffusion and convection will be measured by detecting the motion of oxygen tracer in the liquid. Additional applications for electrochemical cells in semiconductor crystal growth are suggested. Unsteady convection in the melt will also be detected by the appearance of temperature oscillations. The purpose of this study is to experimentally characterize the overstable conditions for a Pb sub 1-x Sn sub x Te melt in the vertical Bridgman crystal growth technique and use a linear analysis to predict the onset of convection for this system.

A study of the effects of phosphates on copper corrosion in drinking water: Copper release, electrochemical, and surface analysis approach

NASA Astrophysics Data System (ADS)

Kang, Young C.

The following work is the study to evaluate the impact of corrosion inhibitors on the copper metal in drinking water and to investigate the corrosion mechanism in the presence and absence of inhibitors. Electrochemical experiments were conducted to understand the effect of specific corrosion inhibitors in synthetic drinking water which was prepared with controlled specific water quality parameters. Water chemistry was studied by Inductively Coupled Plasma--Atomic Emission Spectroscopy (ICP--AES) to investigate the copper leaching rate with time. Surface morphology, crystallinity of corrosion products, copper oxidation status, and surface composition were characterized by various solid surface analysis methods, such as Scanning Electron Microscopy/Energy--Dispersive Spectrometry (SEM/EDS), Grazing-Incidence-angle X-ray Diffraction (GIXRD), X-ray Photoelectron Spectroscopy (XPS), and Time-of-Flight Secondary Ions Mass Spectrometry (ToF-SIMS). The purpose of the first set of experiments was to test various electrochemical techniques for copper corrosion for short term before studying a long term loop system. Surface analysis techniques were carried out to identify and study the corrosion products that form on the fresh copper metal surface when copper coupons were exposed to test solutions for 2 days of experiments time. The second phase of experiments was conducted with a copper pipe loop system in a synthetic tap water over an extended period of time, i.e., 4 months. Copper release and electrochemically measured corrosion activity profiles were monitored carefully with and without corrosion inhibitor, polyphosphate. A correlation between the copper released into the solution and the electrochemically measured corrosion activities was also attempted. To investigate corrosion products on the copper pipe samples, various surface analysis techniques were applied in this study. Especially, static mass spectra acquisition and element distribution mapping were carried out by ToF-SIMS. Dynamic SIMS provided shallow depth profile of corroded copper sample. The third set of the experiments was related to electrochemical noise (EN) measurement through copper coupons to pipes. Calculating corrosion rate of a metal and predicting exactly how long it lasts are problematic since the metal corrosion may be caused by combined corrosion types. Many other metals undergo not only uniform corrosion, but localized corrosion. Uniform corrosion may be conducive for copper pipe to prevent it from further severe corrosion and form passivated film, but localized corrosion causes pinhole leaks and limits the copper pipe applications. The objective of this set of experiment is to discuss the application of electrochemical noise approaches to drinking water copper corrosion problems. Specially, a fundamental description of EN is presented including a discussion of how to interpret the results and technique limitations. Although it was indicated with electrochemical analysis that the corrosion activity was affected by orthophosphate addition in the short-term test, no copper-phosphate complex or compound was found by copper surface characterization. Apparently, orthophosphate can inhibit corrosion by adsorption on the copper surface, but cannot form solid complexes with copper in such a short time, 2 days. When polyphosphate was added into recirculating copper pipe system, copper level increased and polarization resistance decreased. Greenish blue residue on the copper pipe was suspected as copper phosphate complex and corrosion inhibition mechanism was proposed.

The Corrosion Protection of Magnesium Alloy AZ31B

NASA Technical Reports Server (NTRS)

Danford, M. D.; Mendrek, M. J.; Mitchell, M. L.; Torres, P. D.

1997-01-01

Corrosion rates for bare and coated Magnesium alloy AZ31B have been measured. Two coatings, Dow-23(Trademark) and Tagnite(Trademark), have been tested by electrochemical methods and their effectiveness determined. Electrochemical methods employed were the scanning reference electrode technique (SRET), the polarization resistance technique (PR) and the electrochemical impedance spectroscopy technique (EIS). In addition, general corrosion and stress corrosion methods were employed to examine the effectiveness of the above coatings in 90 percent humidity. Results from these studies are presented.

Evaluation of Thymus vulgaris plant extract as an eco-friendly corrosion inhibitor for stainless steel 304 in acidic solution by means of electrochemical impedance spectroscopy, electrochemical noise analysis and density functional theory.

PubMed

Ehsani, A; Mahjani, M G; Hosseini, M; Safari, R; Moshrefi, R; Mohammad Shiri, H

2017-03-15

Inhibition performance of Thymus vulgaris plant leaves extract (thyme) as environmentally friendly (green) inhibitor for the corrosion protection of stainless steel (SS) type 304 in 1.0molL -1 HCl solution was studied by potentiodynamic polarization, electrochemical impedance (EIS) and electrochemical noise measurements (EN) techniques. The EN data were analyzed with FFT technique to make the spectral power density plots. The calculations were performed by MATLAB 2014a software. Geometry optimization and calculation of the structural and electronic properties of the molecular system of inhibitor have been carried out using UB3LYP/6-311++G ∗∗ level. Moreover, the results obtained from electrochemical noise analysis were compared with potentiodynamic polarization and electrochemical impedance spectroscopy. All of the used techniques showed positive effect of green inhibitor with increasing inhibitor concentration. Copyright © 2016 Elsevier Inc. All rights reserved.

Woven electrochemical fabric-based test sensors (WEFTS): a new class of multiplexed electrochemical sensors.

PubMed

Choudhary, Tripurari; Rajamanickam, G P; Dendukuri, Dhananjaya

2015-05-07

We present textile weaving as a new technique for the manufacture of miniature electrochemical sensors with significant advantages over current fabrication techniques. Biocompatible silk yarn is used as the material for fabrication instead of plastics and ceramics used in commercial sensors. Silk yarns are coated with conducting inks and reagents before being handloom-woven as electrodes into patches of fabric to create arrays of sensors, which are then laminated, cut and packaged into individual sensors. Unlike the conventionally used screen-printing, which results in wastage of reagents, yarn coating uses only as much reagent and ink as required. Hydrophilic and hydrophobic yarns are used for patterning so that sample flow is restricted to a small area of the sensor. This simple fluidic control is achieved with readily available materials. We have fabricated and validated individual sensors for glucose and hemoglobin and a multiplexed sensor, which can detect both analytes. Chronoamperometry and differential pulse voltammetry (DPV) were used to detect glucose and hemoglobin, respectively. Industrial quantities of these sensors can be fabricated at distributed locations in the developing world using existing skills and manufacturing facilities. We believe such sensors could find applications in the emerging area of wearable sensors for chemical testing.

Coaxial Lithography

NASA Astrophysics Data System (ADS)

Ozel, Tuncay

The optical and electrical properties of heterogeneous nanowires are profoundly related to their composition and nanoscale architecture. However, the intrinsic constraints of conventional synthetic and lithographic techniques have limited the types of multi-compositional nanowires that can be realized and studied in the laboratory. This thesis focuses on bridging templated electrochemical synthesis and lithography for expanding current synthetic capabilities with respect to materials generality and the ability to tailor two-dimensional growth in the formation of core-shell structures for the rational design and preparation of nanowires with very complex architectures that cannot be made by any other techniques. Chapter 1 introduces plasmonics, templated electrochemical synthesis, and on-wire lithography concepts and their significances within chemistry and materials science. Chapter 2 details a powerful technique for the deposition of metals and semiconductors with nanometer resolution in segment and gap lengths using on-wire lithography, which serves as a new platform to explore plasmon-exciton interactions in the form of long-range optical nanoscale rulers. Chapter 3 highlights an approach for the electrochemical synthesis of solution dispersible core-shell polymeric and inorganic semiconductor nanowires with metallic leads. A photodetector based on a single core-shell semiconductor nanowire is presented to demonstrate the functionality of the nanowires produced using this approach. Chapter 4 describes a new materials general technique, termed coaxial lithography (COAL), bridging templated electrochemical synthesis and lithography for generating coaxial nanowires in a parallel fashion with sub-10 nanometer resolution in both axial and radial dimensions. Combinations of coaxial nanowires composed of metals, metal oxides, metal chalcogenides, conjugated polymers, and a core/shell semiconductor nanowire with an embedded plasmonic nanoring are presented to demonstrate the possibilities afforded by COAL. Chapter 5 addresses the use of COAL for the synthesis of solution dispersible metal nanorings and nanotubes with exceptional architectural tailorability of inner diameter, outer diameter, and length leading to precise spectral control over the resulting plasmonic fields ranging from visible to the near-IR. Chapter 6 is an outlook on templated electrochemical synthesis using coaxial lithography and highlights a few promising applications from nanoparticle assembly to light-matter interactions.

Contribution of Electrochemistry to the Biomedical and Pharmaceutical Analytical Sciences.

PubMed

Kauffmann, Jean-Michel; Patris, Stephanie; Vandeput, Marie; Sarakbi, Ahmad; Sakira, Abdul Karim

2016-01-01

All analytical techniques have experienced major progress since the last ten years and electroanalysis is also involved in this trend. The unique characteristics of phenomena occurring at the electrode-solution interface along with the variety of electrochemical methods currently available allow for a broad spectrum of applications. Potentiometric, conductometric, voltammetric and amperometric methods are briefly reviewed with a critical view in terms of performance of the developed instrumentation with special emphasis on pharmaceutical and biomedical applications.

Characterization of electrochemically deposited polypyrrole using magnetoelastic material transduction elements

NASA Technical Reports Server (NTRS)

Ersoz, Arzu; Ball, J. Christopher; Grimes, Craig A.; Bachas, Leonidas G.

2002-01-01

Magnetoelastic alloy films have been used as a working electrode in an electrochemical cell. This material allows magnetic interrogation of electrochemical deposition. This technique was used to monitor the electrochemical deposition of polypyrrole by multisweep (CV) and potentiostatic methods. Since the determination of the mass-sensitive magnetoelastic film's resonance frequency is based on magnetic transduction, an inherent advantage of this method is that it requires no electrical connections other than the working lead of the potentiostat. Increases in pyrrole deposition correlated with a decrease in the peak resonance frequency of the magnetoelastic alloy. This technique provides a novel approach by which one can monitor electrochemical processes.

New natural product -an efficient antimicrobial applications of new newly synthesized pyrimidine derivatives by the electrochemical oxidation of hydroxyl phenol in the presence of 2-mercapto-6-(trifluoromethyl) pyrimidine-4-ol as nucleophile.

PubMed

Khan, Zia Ul Haq; Khan, Amjad; Wan, Pingyu; Khan, Arif Ullah; Tahir, Kamran; Muhammad, Nawshad; Khan, Faheem Ullah; Shah, Hidayat Ullah; Khan, Zia Ullah

2018-05-01

Some new pyrimidine derivatives have been synthesised by electrochemical oxidation of catechol (1a) in the existence of 2-mercapto-6-(trifluoromethyl) pyrimidine-4-ol (3) as a nucleophile in aqueous solution using Cyclic Voltammetric and Controlled Potential Coulometry. The catechol has been oxidised to o-quinone through electrochemical method and participative in Michael addition reaction, leading to the development of some new pyrimidine derivatives. The products were achieved in good yield with high pureness. The mechanism of the reaction has been conformed from the Cyclic Voltammetric data and Controlled Potential Coulometry. After purification, the compounds were characterised using modern techniques. The synthesised materials were screened for antimicrobial actions using Gram positive and Gram negative strain of bacteria. These new synthesised pyrimidine derivatives showed very good antimicrobial activity.

Recent advances in polymer supporting layered double hydroxides nanocomposite for electrochemical biosensors

NASA Astrophysics Data System (ADS)

Dhanasekaran, T.; Padmanaban, A.; Gnanamoorthy, G.; Manigandan, R.; Praveen Kumar, S.; Stephen, A.; Narayanan, V.

2018-01-01

In recent years, layered double hydroxides (LDHs) materials having emerging due to their ability of intercalate a variety of anions, either organic or inorganic molecules. The most significance of the LDHs has been found potential applications in catalysis, wastewater treatment, and electrochemical sensors. The Mg-Al LDHs (MAL) and Poly-o-phenylenediamine @ Mg-Al LDHs (P-MAL) was prepared via simple one step hydrothermal method. As prepared material was characterized using many techniques such as, the structural and crystal phase was determined from XRD and Raman analyses. The functional groups were depicted using FT-IR spectroscopy. The optical propertied studied using diffuse reflectance spectroscopy UV-vis spectroscopy and the emission property were analyzed from Photoluminescence spectroscopy. The surface morphology and average particle size was analyzed using FESEM microscopy. The prepared polymer composite material P-MAL was further used for highly sensitive electrochemical detection towards dopamine (DA).

Interconnecting Carbon Fibers with the In-situ Electrochemically Exfoliated Graphene as Advanced Binder-free Electrode Materials for Flexible Supercapacitor.

PubMed

Zou, Yuqin; Wang, Shuangyin

2015-07-07

Flexible energy storage devices are highly demanded for various applications. Carbon cloth (CC) woven by carbon fibers (CFs) is typically used as electrode or current collector for flexible devices. The low surface area of CC and the presence of big gaps (ca. micro-size) between individual CFs lead to poor performance. Herein, we interconnect individual CFs through the in-situ exfoliated graphene with high surface area by the electrochemical intercalation method. The interconnected CFs are used as both current collector and electrode materials for flexible supercapacitors, in which the in-situ exfoliated graphene act as active materials and conductive "binders". The in-situ electrochemical intercalation technique ensures the low contact resistance between electrode (graphene) and current collector (carbon cloth) with enhanced conductivity. The as-prepared electrode materials show significantly improved performance for flexible supercapacitors.

Single-Step Reagentless Laser Scribing Fabrication of Electrochemical Paper-Based Analytical Devices.

PubMed

de Araujo, William R; Frasson, Carolina M R; Ameku, Wilson A; Silva, José R; Angnes, Lúcio; Paixão, Thiago R L C

2017-11-20

A single-step laser scribing process is used to pattern nanostructured electrodes on paper-based devices. The facile and low-cost technique eliminates the need for chemical reagents or controlled conditions. This process involves the use of a CO 2 laser to pyrolyze the surface of the paperboard, producing a conductive porous non-graphitizing carbon material composed of graphene sheets and composites with aluminosilicate nanoparticles. The new electrode material was extensively characterized, and it exhibits high conductivity and an enhanced active/geometric area ratio; it is thus well-suited for electrochemical purposes. As a proof-of-concept, the devices were successfully employed for different analytical applications in the clinical, pharmaceutical, food, and forensic fields. The scalable and green fabrication method associated with the features of the new material is highly promising for the development of portable electrochemical devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical DNA hybridization sensors based on conducting polymers.

PubMed

Rahman, Md Mahbubur; Li, Xiao-Bo; Lopa, Nasrin Siraj; Ahn, Sang Jung; Lee, Jae-Joon

2015-02-05

Conducting polymers (CPs) are a group of polymeric materials that have attracted considerable attention because of their unique electronic, chemical, and biochemical properties. This is reflected in their use in a wide range of potential applications, including light-emitting diodes, anti-static coating, electrochromic materials, solar cells, chemical sensors, biosensors, and drug-release systems. Electrochemical DNA sensors based on CPs can be used in numerous areas related to human health. This review summarizes the recent progress made in the development and use of CP-based electrochemical DNA hybridization sensors. We discuss the distinct properties of CPs with respect to their use in the immobilization of probe DNA on electrode surfaces, and we describe the immobilization techniques used for developing DNA hybridization sensors together with the various transduction methods employed. In the concluding part of this review, we present some of the challenges faced in the use of CP-based DNA hybridization sensors, as well as a future perspective.

Fe2P as a novel efficient catalyst promoter in Pd/C system for formic acid electro-oxidation in fuel cells reaction

NASA Astrophysics Data System (ADS)

Wang, Fulong; Xue, Huaiguo; Tian, Zhiqun; Xing, Wei; Feng, Ligang

2018-01-01

Developing catalyst promoter for Pd/C catalyst is significant for the catalytic ability improvement in energy transfer related electrochemical reactions. Herein, we demonstrate Fe2P as an efficient catalyst promoter in Pd/C catalyst system for formic acid electro-oxidation in fuel cells reactions. Adding Fe2P in the Pd/C catalyst system greatly increases the performances for formic acid oxidation by 3-4 times; the CO stripping technique displays two kinds of active sites formation in the Pd-Fe2P/C catalyst system coming from the interaction of Pd, Fe2P and Pd oxide species and both are more efficient for formic acid and CO-species electrooxidation. The smaller charge transfer resistance and Tafel slope for formic acid oxidation indicate the improvements in kinetics by Fe2P in the Pd-Fe2P/C system. The nanostructured hybrid units of Pd, Fe2P and carbon are evidently visible in the high resolution microscopy images and XPS technique confirmes the electronic effect in the catalyst system. The promotion effect of Fe2P in the catalyst system arising from the structure, composition and electronic effect changes is discussed with the help from multiple physical and electrochemical techniques. It is concluded that Fe2P as a significant catalyst promoter will have potential application in energy transfer related electrochemical reactions.

Synthesis of flower-like molybdenum sulfide/graphene hybrid as an efficient oxygen reduction electrocatalyst for anion exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Arunchander, A.; Peera, S. Gouse; Sahu, A. K.

2017-06-01

Nanostructured transition metal chalcogenides (TMCs) have significant interest towards electrochemical devices such as fuel cells, metal-ion batteries, due to their unique physical and electrochemical properties. Herein, we report a facile hydrothermal synthesis of flower-like nanostructured molybdenum sulphide and its incorporation on to graphene as a potential oxygen reduction reaction catalyst in alkaline medium. The phase purity and morphological evolution of MoS2 is systematically studied through X-ray diffraction and scanning electron microscopic techniques. The electronic states of metal and non-metallic species are deeply studied by X-ray photoelectron spectroscopy. The effect of annealing temperatures and TMC concentrations are also investigated by electrochemical techniques such as cyclic and linear sweep voltammograms. The optimised electrocatalyst (MoS2/G-500) delivers significant ORR activity with onset and half-wave potentials of 0.91 and 0.80 V (vs. RHE), respectively. Superior durability compared to state-of-art Pt/C catalyst is ascertained by repeating potential cycles for about 5000 times and also by chronoamperometric technique. Finally, the hybrid catalyst is evaluated in AEMFC as cathode catalyst which delivers peak power density of about 29 mW cm-2 under ambient temperature and pressure. The present findings emphasis that MoS2/G catalyst is promising as cost-effective and alternative to noble metal-based catalysts for fuel cell applications.

Designing of fluorescent and magnetic imprinted polymer for rapid, selective and sensitive detection of imidacloprid via activators regenerated by the electron transfer-atom transfer radical polymerization (ARGET-ATRP) technique

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Karfa, Paramita; Madhuri, Rashmi; Sharma, Prashant K.

2018-05-01

In this work, we report on a dual-behavior electrochemical/optical sensor for sensitive determination of Imidacloprid by fluorescent dye (fluorescein, FL) and imprinted polymer modified europium doped superparamagnetic iron oxide nanoparticles (FL@SPIONs@MIP). The imidacloprid (IMD)-imprinted polymer was directly synthesized on the Eu-SPIONs surface via Activators regenerated by the electron transfer-atom transfer radical polymerization (ARGET-ATRP) technique. Preparation, characterization and application of the prepared FL@SPIONs@MIP were systematically investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), fluorescence spectroscopy and electrochemical techniques. The electrochemical experiments exhibited a remarkable selectivity of the prepared sensor towards IMD. Determination of IMD by the square wave stripping voltammetry method represented a wide linear range of 0.059-0.791 μg L-1 with a detection limit of 0.0125 μg L-1. In addition, the fluorescence method shows a linear range of 0.039-0.942 μg L-1 and LOD of 0.0108 μg L-1. The fluorescence property of prepared FL@SPIONs@MIP was used for rapid, on-spot but selective detection of IMD in real samples. The proposed electrode displayed excellent repeatability and long-term stability and was successfully applied for quantitative and trace level determination of IMD in several real samples.

In situ electrochemical investigations of the kinetic and thermodynamic properties of nickel-metal hydride traction batteries

NASA Astrophysics Data System (ADS)

Yang, Xiao Guang; Liaw, Bor Yann

Although large ampere hour nickel-metal hydride (Ni-MH) traction batteries are in the stage of being commercialized for electric and hybrid vehicle applications, little is known about their performance characteristics. By using a standard Hg/HgO reference electrode in a commercial Ni-MH battery, we were able to conduct in situ measurements to determine both kinetic and thermodynamic properties of the system, including the characteristics of individual electrodes. Using the galvanostatic intermittent titration technique (GITT), we simultaneously and effectively determined the open-circuit voltage of the battery, the equilibrium electrode potentials, and the diffusion coefficient of proton and hydrogen in the nickel and metal hydride electrode, respectively, as a function of the states of charge (SOC). Using the current-step excitation technique, we found that the internal resistance of the battery primarily comes from the metal hydride electrode, which is greater by one order of magnitude than that of the Ni electrode. The cyclic linear micro-polarization experiments, on the other hand, showed that the charge-transfer resistance of the electrochemical reaction at the metal hydride electrode is about twice larger than that of the Ni counterpart above 20% SOC. In comparison, the internal resistance is an order of magnitude smaller than those of the electrochemical charge-transfer reactions. The micro-polarization technique also allowed us to calculate the exchange current densities of the respective electrode electrochemical reactions and the associated specific exchange current densities. These in situ, simple but detailed, characterizations of the thermodynamic and kinetic properties of the Ni-MH system provided valuable information for better understanding of the battery performance.

High-Resolution Graphene Films for Electrochemical Sensing via Inkjet Maskless Lithography.

PubMed

Hondred, John A; Stromberg, Loreen R; Mosher, Curtis L; Claussen, Jonathan C

2017-10-24

Solution-phase printing of nanomaterial-based graphene inks are rapidly gaining interest for fabrication of flexible electronics. However, scalable manufacturing techniques for high-resolution printed graphene circuits are still lacking. Here, we report a patterning technique [i.e., inkjet maskless lithography (IML)] to form high-resolution, flexible, graphene films (line widths down to 20 μm) that significantly exceed the current inkjet printing resolution of graphene (line widths ∼60 μm). IML uses an inkjet printed polymer lacquer as a sacrificial pattern, viscous spin-coated graphene, and a subsequent graphene lift-off to pattern films without the need for prefabricated stencils, templates, or cleanroom technology (e.g., photolithography). Laser annealing is employed to increase conductivity on thermally sensitive, flexible substrates [polyethylene terephthalate (PET)]. Laser annealing and subsequent platinum nanoparticle deposition substantially increases the electroactive nature of graphene as illustrated by electrochemical hydrogen peroxide (H 2 O 2 ) sensing [rapid response (5 s), broad linear sensing range (0.1-550 μm), high sensitivity (0.21 μM/μA), and low detection limit (0.21 μM)]. Moreover, high-resolution, complex graphene circuits [i.e., interdigitated electrodes (IDE) with varying finger width and spacing] were created with IML and characterized via potassium chloride (KCl) electrochemical impedance spectroscopy (EIS). Results indicated that sensitivity directly correlates to electrode feature size as the IDE with the smallest finger width and spacing (50 and 50 μm) displayed the largest response to changes in KCl concentration (∼21 kΩ). These results indicate that the developed IML patterning technique is well-suited for rapid, solution-phase graphene film prototyping on flexible substrates for numerous applications including electrochemical sensing.

Technology advancement of the electrochemical CO2 concentrating process

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Woods, R. R.; Hallick, T. M.; Heppner, D. B.

1978-01-01

The overall objectives of the present program are to: (1) improve the performance of the electrochemical CO2 removal technique by increasing CO2 removal efficiencies at pCO2 levels below 400 Pa, increasing cell power output and broadening the tolerance of electrochemical cells for operation over wide ranges of cabin relative humidity; (2) design, fabricate, and assemble development hardware to continue the evolution of the electrochemical concentrating technique from the existing level to an advanced level able to efficiently meet the CO2 removal needs of a spacecraft air revitalization system (ARS); (3) develop and incorporate into the EDC the components and concepts that allow for the efficient integration of the electrochemical technique with other subsystems to form a spacecraft ARS; (4) combine ARS functions to enable the elimination of subsystem components and interfaces; and (5) demonstrate the integration concepts through actual operation of a functionally integrated ARS.

A study for hypergolic vapor sensor development

NASA Technical Reports Server (NTRS)

Stetter, J. R.

1977-01-01

The use of an electrochemical technique for MMH and N02 measurement was investigated. Specific MMH and N02 electrochemical sensors were developed. Experimental techniques for preparation, handling, and analysis of hydrazine's vapor mixtures at ppb and ppm levels were developed. Two approaches to N02 instrument design were evaluated including specific adsorption and specific electrochemical reduction. Two approaches to hydrazines monitoring were evaluated including catalytic conversion to N0 with subsequent N0 detection and direct specific electrochemical oxidation. Two engineering prototype MMH/N02 monitors were designed and constructed.

Label-free Detection of Influenza Viruses using a Reduced Graphene Oxide-based Electrochemical Immunosensor Integrated with a Microfluidic Platform

NASA Astrophysics Data System (ADS)

Singh, Renu; Hong, Seongkyeol; Jang, Jaesung

2017-02-01

Reduced graphene oxide (RGO) has recently gained considerable attention for use in electrochemical biosensing applications due to its outstanding conducting properties and large surface area. This report presents a novel microfluidic chip integrated with an RGO-based electrochemical immunosensor for label-free detection of an influenza virus, H1N1. Three microelectrodes were fabricated on a glass substrate using the photolithographic technique, and the working electrode was functionalized using RGO and monoclonal antibodies specific to the virus. These chips were integrated with polydimethylsiloxane microchannels. Structural and morphological characterizations were performed using X-ray photoelectron spectroscopy and scanning electron microscopy. Electrochemical studies revealed good selectivity and an enhanced detection limit of 0.5 PFU mL-1, where the chronoamperometric current increased linearly with H1N1 virus concentration within the range of 1 to 104 PFU mL-1 (R2 = 0.99). This microfluidic immunosensor can provide a promising platform for effective detection of biomolecules using minute samples.

Excimer laser assisted very fast exfoliation and reduction of graphite oxide at room temperature under air ambient for Supercapacitors electrode

NASA Astrophysics Data System (ADS)

Malek Hosseini, S. M. B.; Baizaee, S. M.; Naderi, Hamid Reza; Dare Kordi, Ali

2018-01-01

Excimer laser was used for reduction and exfoliation of graphite oxide (GO) at room temperature under air ambient. The prepared excimer laser reduced graphite oxide (XLRGO) is characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), nitrogen adsorption/desorption (BET method), X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and UV-vis absorption techniques for surface, structural functional groups and band gap analysis. Electrochemical properties are investigated using cyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance spectroscopy (EIS) and continues cyclic voltammetry (CCV) in 0.5 M Na2SO4 as electrolyte. Electrochemical investigations revealed that XLRGO electrode has enhanced supercapacitive performance including specific capacitance of 299 F/g at a scan rate of 2 mV/s. Furthermore, CCV measurement showed that XLRGO electrode kept 97.8% of its initial capacitance/capacity after 4000 cycles. The obtained results from electrochemical investigations confirm that the reduction of GO by using an excimer laser produces high-quality graphene for supercapacitor applications without the need for additional operations.

Microfluidic electrochemical assay for rapid detection and quantification of Escherichia coli.

PubMed

Safavieh, Mohammadali; Ahmed, Minhaz Uddin; Tolba, Mona; Zourob, Mohammed

2012-01-15

Microfluidic electrochemical biosensor for performing Loop-mediated isothermal amplification (LAMP) was developed for the detection and quantification of Escherichia coli. The electrochemical detection for detecting the DNA amplification was achieved using Hoechst 33258 redox molecule and linear sweep voltametry (LSV). The DNA aggregation and minor groove binding with redox molecule cause a significant drop in the anodic oxidation of LSV. Unlike other electrochemical techniques, this method does not require the probe immobilization and the detection of the bacteria can be accomplished in a single chamber without DNA extraction and purification steps. The isothermal amplification time has a major role in the quantification of the bacteria. We have shown that we could detect and quantify 24 CFU/ml of bacteria and 8.6 fg/μl DNA in 60 min and 48 CFU/ml of bacteria in 35 min in LB media and urine samples. We believe that this microfluidic chip has great potential to be used as a point of care diagnostic (POC) device in the clinical/hospital application. Copyright © 2011 Elsevier B.V. All rights reserved.

Electrochemical writing on edible polysaccharide films for intelligent food packaging.

PubMed

Wu, Si; Wang, Wenqi; Yan, Kun; Ding, Fuyuan; Shi, Xiaowen; Deng, Hongbing; Du, Yumin

2018-04-15

Polysaccharide films used as intelligent food packaging possess the advantages of renewability, safety and biodegradability. Printing on the polysaccharidic food packaging is challenging due to the high demand for edible-ink and the need for a suitable printing technique. In this work, we propose an electrochemical method for writing on polysaccharide film. Unlike conventional printing, this electrochemical writing process relies on the pH responsive color change of anthocyanin embedded in the chitosan/agarose hydrogel. By biasing a negative potential to a stainless wire (used as a pen) contacting the surface of the chitosan/agarose/ATH hydrogel, the locally generated pH change induced the color change of ATH and wrote programmed information on the hydrogel. We demonstrate the writing can be temporary in the hydrogel but stable when the hydrogel is dried. We further demonstrate that the written film is applicable for the detection of the spoilage of crucian fish. The reported electrochemical writing process provides a novel method for printing information on polysaccharide film and great potential for intelligent food packaging. Copyright © 2018 Elsevier Ltd. All rights reserved.

Advanced carbon manufacturing for energy and biological applications

NASA Astrophysics Data System (ADS)

Turon Teixidor, Genis

The science of miniaturization has experienced revolutionary advances during the last decades, witnessing the development of the Integrated Circuit and the emergence of MEMS and Nanotechnology. Particularly, MEMS technology has pioneered the use of non-traditional materials in microfabrication by including polymers, ceramics and composites to the well known list of metals and semiconductors. One of the latest additions to this set of materials is carbon, which represents a very important inclusion given its significance in electrochemical energy conversion systems and in applications where it is used as sensor probe material. For these applications, carbon is optimal in several counts: It has a wide electrochemical stability window, good electrical and thermal conductivity, high corrosion resistance and mechanical stability, and is available in high purity at a low cost. Furthermore carbon is biocompatible. This thesis presents several microfabricated devices that take advantage of these properties. The thesis has two clearly differentiated parts. In the first one, applications of micromachined carbon in the field of energy conversion and energy storage are presented. These applications include lithium ion micro batteries and the development of new carbon electrodes with fractal geometries. In the second part, the focus shifts to biological applications. First, the study of the interaction of living cells with micromachined carbon is presented, followed by the description of a sensor based on interdigitated nano-electrode arrays, and finally the development of the new instrumentation needed to address arrays of carbon electrodes, a multiplexed potentiostat. The underlying theme that connects all these seemingly different topics is the use of carbon microfabrication techniques in electrochemical systems.

An electrochemical immunosensor for quantitative detection of ficolin-3

NASA Astrophysics Data System (ADS)

San, Lili; Zeng, Dongdong; Song, Shiping; Zuo, Xiaolei; Zhang, Huan; Wang, Chenguang; Wu, Jiarui; Mi, Xianqiang

2016-06-01

Diabetes mellitus (DM) is one of the most common metabolic disorders in the world, of which more than 90% is type-2 diabetes mellitus (T2DM). There is a rather urgent need for reliable, sensitive and quick detection techniques in clinical application of T2DM. Ficolin-3 is a potential biomarker of T2DM, because serum ficolin-3 levels are associated with insulin resistance and predict the incidence of T2DM. Herein, a sandwich-type electrochemical immunosensor was developed for the detection of ficolin-3 in human serum. Cyclic voltammetry and the amperometric current versus time were used to characterize the performance of the immunosensor. Under optimal conditions, the detection limitation of ficolin-3 was 100 ng ml-1 and the linear dynamic range was between 2 and 50 μg ml-1. The method has ideal accuracy, excellent stability and selectivity and has wide application prospects in clinical research.

Application of gas diffusion electrodes in bioelectrochemical syntheses and energy conversion.

PubMed

Horst, Angelika E W; Mangold, Klaus-Michael; Holtmann, Dirk

2016-02-01

Combining the advantages of biological components (e.g., reaction specificity, self-replication) and electrochemical techniques in bioelectrochemical systems offers the opportunity to develop novel efficient and sustainable processes for the production of a number of valuable products. The choice of electrode material has a great impact on the performance of bioelectrochemical systems. In addition to the redox process at the electrodes, interactions of biocatalysts with electrodes (e.g., enzyme denaturation or biofouling) need to be considered. In recent years, gas diffusion electrodes (GDEs) have proved to be very attractive electrodes for bioelectrochemical purposes. GDEs are porous electrodes, that posses a large three-phase boundary surface. At this interface, a solid catalyst supports the electrochemical reaction between gaseous and liquid phase. This mini-review discusses the application of GDEs in microbial and enzymatic fuel cells, for microbial electrolysis, in biosensors and for electroenzymatic synthesis reactions. © 2015 Wiley Periodicals, Inc.

C-MEMS for bio-sensing applications

NASA Astrophysics Data System (ADS)

Song, Yin; Agrawal, Richa; Wang, Chunlei

2015-05-01

Developing highly sensitive, selective, and reproducible miniaturized bio-sensing platforms require reliable biointerface which should be compatible with microfabrication techniques. In this study, we have fabricated pyrolyzed carbon arrays with high surface area as a bio-sensing electrode, and developed the surface functionalization methods to increase biomolecules immobilization efficiency and further understand electrochemical phenomena at biointerfaces. The carbon microelectrode arrays with high aspect ratio have been fabricated by carbon microelectromechanical systems (C-MEMS) and nanomaterials such as graphene have been integrated to further increase surface area. To achieve the efficient covalent immobilization of biomolecules, various oxidation and reduction functionalization methods have been investigated. The oxidation treatment in this study includes vacuum ultraviolet, electrochemical activation, UV/Ozone and oxygen RIE. The reduction treatment includes direct amination and diazonium grafting. The developed bio-sensing platform was then applied for several applications, such as: DNA sensor; H2O2 sensor; aptamer sensor and HIV sensor.

Macro-mechanics controls quantum mechanics: mechanically controllable quantum conductance switching of an electrochemically fabricated atomic-scale point contact.

PubMed

Staiger, Torben; Wertz, Florian; Xie, Fangqing; Heinze, Marcel; Schmieder, Philipp; Lutzweiler, Christian; Schimmel, Thomas

2018-01-12

Here, we present a silver atomic-scale device fabricated and operated by a combined technique of electrochemical control (EC) and mechanically controllable break junction (MCBJ). With this EC-MCBJ technique, we can perform mechanically controllable bistable quantum conductance switching of a silver quantum point contact (QPC) in an electrochemical environment at room temperature. Furthermore, the silver QPC of the device can be controlled both mechanically and electrochemically, and the operating mode can be changed from 'electrochemical' to 'mechanical', which expands the operating mode for controlling QPCs. These experimental results offer the perspective that a silver QPC may be used as a contact for a nanoelectromechanical relay.

Electrochemically controlled drug-mimicking protein release from iron-alginate thin-films associated with an electrode.

PubMed

Jin, Zhiyuan; Güven, Güray; Bocharova, Vera; Halámek, Jan; Tokarev, Ihor; Minko, Sergiy; Melman, Artem; Mandler, Daniel; Katz, Evgeny

2012-01-01

Novel biocompatible hybrid-material composed of iron-ion-cross-linked alginate with embedded protein molecules has been designed for the signal-triggered drug release. Electrochemically controlled oxidation of Fe(2+) ions in the presence of soluble natural alginate polymer and drug-mimicking protein (bovine serum albumin, BSA) results in the formation of an alginate-based thin-film cross-linked by Fe(3+) ions at the electrode interface with the entrapped protein. The electrochemically generated composite thin-film was characterized by electrochemistry and atomic force microscopy (AFM). Preliminary experiments demonstrated that the electrochemically controlled deposition of the protein-containing thin-film can be performed at microscale using scanning electrochemical microscopy (SECM) as the deposition tool producing polymer-patterned spots potentially containing various entrapped drugs. Application of reductive potentials on the modified electrode produced Fe(2+) cations which do not keep complexation with alginate, thus resulting in the electrochemically triggered thin-film dissolution and the protein release. Different experimental parameters, such as the film-deposition time, concentrations of compounds and applied potentials, were varied in order to demonstrate that the electrodepositon and electrodissolution of the alginate composite film can be tuned to the optimum performance. A statistical modeling technique was applied to find optimal conditions for the formation of the composite thin-film for the maximal encapsulation and release of the drug-mimicking protein at the lowest possible potential. © 2011 American Chemical Society

Decontamination of Petroleum-Contaminated Soils Using The Electrochemical Technique: Remediation Degree and Energy Consumption.

PubMed

Streche, Constantin; Cocârţă, Diana Mariana; Istrate, Irina-Aura; Badea, Adrian Alexandru

2018-02-19

Currently, there are different remediation technologies for contaminated soils, but the selection of the best technology must be not only the treatment efficiency but also the energy consumption (costs) during its application. This paper is focused on assessing energy consumption related to the electrochemical treatment of polluted soil with petroleum hydrocarbons. In the framework of a research project, two types of experiments were conducted using soil that was artificially contaminated with diesel fuel at the same level of contamination. The experimental conditions considered for each experiment were: different amounts of contaminated soils (6 kg and 18 kg, respectively), the same current intensity level (0.25A and 0.5A), three different contamination degrees (1%, 2.5% and 5%) and the same time for application of the electrochemical treatment. The remediation degree concerning the removal of petroleum hydrocarbons from soil increased over time by approximately 20% over 7 days. With regard to energy consumption, the results revealed that with an increase in the quantity of treated soil of approximately three times, the specific energy consumption decreased from 2.94 kWh/kg treated soil to 1.64 kWh/kg treated soil.

Activated carbon electrode from banana-peel waste for supercapacitor applications

NASA Astrophysics Data System (ADS)

Taer, E.; Taslim, R.; Aini, Z.; Hartati, S. D.; Mustika, W. S.

2017-01-01

Seven types of activated carbon electrode (ACM) have been produced from the banana peel waste for supercapacitor application. The difference type of the electrode was synthesized by the various conditions of carbonization and activation. The production of the ACM was begun by the milling process and molded by a solution casting technique. The next step was followed by drying, carbonization and activation process. Physical properties of the ACM were studied by the N2 gas absorption-desorption method to characterize the specific surface area of the sample. On the other side, the electrochemical properties such as specific capacitance (Csp), specific energy (E) and specific power (P) were resulted by calculating the current (I) and voltage (V) data from the cyclic voltammetry testing. Based on the data obtained the surface area of the ACM has a significant relationship with the electrochemical properties. The specific surface area (SBET), Csp, E and P were found the maximum value as high as 581m2 / g, 68 F/g, 0.75 Wh/kg and 31 W/kg, respectively. Further more, this paper were also analyzed the relationship between electrochemical properties of supercapacitor with the degree of crystallization of the ACM.

Novel Membrane-Based Electrochemical Sensor for Real-Time Bio-Applications

PubMed Central

Alatraktchi, Fatima AlZahra'a; Bakmand, Tanya; Dimaki, Maria; Svendsen, Winnie E.

2014-01-01

This article presents a novel membrane-based sensor for real-time electrochemical investigations of cellular- or tissue cultures. The membrane sensor enables recording of electrical signals from a cell culture without any signal dilution, thus avoiding loss of sensitivity. Moreover, the porosity of the membrane provides optimal culturing conditions similar to existing culturing techniques allowing more efficient nutrient uptake and molecule release. The patterned sensor electrodes were fabricated on a porous membrane by electron-beam evaporation. The electrochemical performance of the membrane electrodes was characterized by cyclic voltammetry and chronoamperometry, and the detection of synthetic dopamine was demonstrated down to a concentration of 3.1 pM. Furthermore, to present the membrane-sensor functionality the dopamine release from cultured PC12 cells was successfully measured. The PC12 cells culturing experiments showed that the membrane-sensor was suitable as a cell culturing substrate for bio-applications. Real-time measurements of dopamine exocytosis in cell cultures were performed, where the transmitter release was recorded at the point of release. The developed membrane-sensor provides a new functionality to the standard culturing methods, enabling sensitive continuous in vitro monitoring and closely mimicking the in vivo conditions. PMID:25421738

Nanometric MgFe2O4: Synthesis, characterization and its application towards supercapacitor and electrochemical uric acid sensor

NASA Astrophysics Data System (ADS)

Majumder, S.; Kumar, S.; Banerjee, S.

2017-05-01

In this paper, we have synthesized nanocrystalline MgFe2O4 (S1) by auto-combustion assisted sol-gel method. The structure and morphology and elemental study of S1 are examined by powder X-ray diffraction (PXRD), field emission scanning electron microscopic (FESEM) and energy dispersive X-ray spectroscopic (EDS) techniques. The FESEM images reveal that the morphology of the sample is rough and average particle size is 50 nm. The PXRD study indicates that the samples are well crystalline and single phase in nature. Moreover, we have performed supercapacitor study by electrochemical galvanostatic charge-discharge (GCD) measurement, which shows pseudo capacitive behavior. S1 contains a high specific capacitance of 428.9 Fg-1 at the current density 0.0625 Ag-1 and can deliver high energy and power density of 18.01 Wh kg-1 and 21468 Wkg-1 respectively. Moreover, uric acid (UA) sensing study has also been performed by cyclic voltmetry (CV) and electrochemical impedance spectroscopy measurement (EIS) of S1. We can use nanocrystalline MgFe2O4 as supercapacitor and UA sensor applications purpose.

Ambient synthesis, characterization, and electrochemical activity of LiFePO₄ nanomaterials derived from iron phosphate intermediates

DOE PAGES

Patete, Jonathan M.; Wong, Stanislaus S.; Scofield, Megan E.; ...

2015-05-30

LiFePO₄ materials have become increasingly popular as a cathode material due to the many benefits they possess including thermal stability, durability, low cost, and long life span. Nevertheless, to broaden the general appeal of this material for practical electrochemical applications, it would be useful to develop a relatively mild, reasonably simple synthesis method of this cathode material. Herein, we describe a generalizable, 2-step methodology of sustainably synthesizing LiFePO₄ by incorporating a template-based, ambient, surfactantless, seedless, U-tube protocol in order to generate size and morphologically tailored, crystalline, phase-pure nanowires. The purity, composition, crystallinity, and intrinsic quality of these wires were systematicallymore » assessed using transmission electron microscopy TEM, HRTEM, SEM, XRD, SAED, EDAX and high-resolution synchrotron XRD. From these techniques, we were able to determine that there is an absence of defects present in our wires, supporting the viability of our synthetic approach. Electrochemical analysis was also employed to assess their electrochemical activity. Although our nanowires do not contain any noticeable impurities, we attribute their less than optimal electrochemical rigor to differences in the chemical bonding between our LiFePO₄ nanowires and their bulk-like counterparts. Specifically, we demonstrate for the first time experimentally that the Fe-O3 chemical bond plays an important role in determining the overall conductivity of the material, an assertion which is further supported by recent first principles calculations. Nonetheless, our ambient, solution-based synthesis technique is capable of generating highly crystalline and phase-pure energy-storage-relevant nanowires that can be tailored so as to fabricate different sized materials of reproducible, reliable morphology.« less

X-ray Absorption Spectroscopy Characterization of Electrochemical Processes in Renewable Energy Storage and Conversion Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmand, Maryam

2013-05-19

The development of better energy conversion and storage devices, such as fuel cells and batteries, is crucial for reduction of our global carbon footprint and improving the quality of the air we breathe. However, both of these technologies face important challenges. The development of lower cost and better electrode materials, which are more durable and allow more control over the electrochemical reactions occurring at the electrode/electrolyte interface, is perhaps most important for meeting these challenges. Hence, full characterization of the electrochemical processes that occur at the electrodes is vital for intelligent design of more energy efficient electrodes. X-ray absorption spectroscopymore » (XAS) is a short-range order, element specific technique that can be utilized to probe the processes occurring at operating electrode surfaces, as well for studying the amorphous materials and nano-particles making up the electrodes. It has been increasingly used in recent years to study fuel cell catalysts through application of the and #916; and mgr; XANES technique, in combination with the more traditional X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) techniques. The and #916; and mgr; XANES data analysis technique, previously developed and applied to heterogeneous catalysts and fuel cell electrocatalysts by the GWU group, was extended in this work to provide for the first time space resolved adsorbate coverages on both electrodes of a direct methanol fuel cell. Even more importantly, the and #916; and mgr; technique was applied for the first time to battery relevant materials, where bulk properties such as the oxidation state and local geometry of a cathode are followed.« less

High Frequency Electromechanical Imaging of Ferroelectrics in a Liquid Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jesse, Stephen; Chu, Ying-Hao; Kalinin, Sergei V

The coupling between electrical and mechanical phenomena is a ubiquitous feature of many information and energy storage materials and devices. In addition to involvement in performance and degradation mechanisms, electromechanical effects underpin a broad spectrum of nanoscale imaging and spectroscopies including piezoresponse force and electrochemical strain microscopies. Traditionally, these studies are conducted under ambient conditions. However, applications related to imaging energy storage and electrophysiological phenomena require operation in a liquid phase and therefore the development of electromechanical probing techniques suitable to liquid environments. Due to the relative high conductivity of most liquids and liquid decomposition at low voltages, the transfermore » of characterization techniques from ambient to liquid is not straightforward. Here we present a detailed study of ferroelectric domain imaging and manipulation in thin film BiFeO{sub 3} using piezoresponse force microscopy in liquid environments as model systems for electromechanical phenomena in general. We explore the use of contact resonance enhancement and the application of multifrequency excitation and detection principles to overcome the experimental problems introduced by a liquid environment. Understanding electromechanical sample characterization in liquid is a key aspect not only for ferroelectric oxides but also for biological and electrochemical sample systems.« less

Microbial ecology-based engineering of Microbial Electrochemical Technologies.

PubMed

Koch, Christin; Korth, Benjamin; Harnisch, Falk

2018-01-01

Microbial ecology is devoted to the understanding of dynamics, activity and interaction of microorganisms in natural and technical ecosystems. Bioelectrochemical systems represent important technical ecosystems, where microbial ecology is of highest importance for their function. However, whereas aspects of, for example, materials and reactor engineering are commonly perceived as highly relevant, the study and engineering of microbial ecology are significantly underrepresented in bioelectrochemical systems. This shortfall may be assigned to a deficit on knowledge and power of these methods as well as the prerequisites for their thorough application. This article discusses not only the importance of microbial ecology for microbial electrochemical technologies but also shows which information can be derived for a knowledge-driven engineering. Instead of providing a comprehensive list of techniques from which it is hard to judge the applicability and value of information for a respective one, this review illustrates the suitability of selected techniques on a case study. Thereby, best practice for different research questions is provided and a set of key questions for experimental design, data acquisition and analysis is suggested. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Advanced Materials and Fabrication Techniques for the Orion Attitude Control Motor

NASA Technical Reports Server (NTRS)

Gorti, Sridhar; Holmes, Richard; O'Dell, John; McKechnie, Timothy; Shchetkovskiy, Anatoliy

2013-01-01

Rhenium, with its high melting temperature, excellent elevated temperature properties, and lack of a ductile-to-brittle transition temperature (DBTT), is ideally suited for the hot gas components of the ACM (Attitude Control Motor), and other high-temperature applications. However, the high cost of rhenium makes fabricating these components using conventional fabrication techniques prohibitive. Therefore, near-net-shape forming techniques were investigated for producing cost-effective rhenium and rhenium alloy components for the ACM and other propulsion applications. During this investigation, electrochemical forming (EL-Form ) techniques were evaluated for producing the hot gas components. The investigation focused on demonstrating that EL-Form processing techniques could be used to produce the ACM flow distributor. Once the EL-Form processing techniques were established, a representative rhenium flow distributor was fabricated, and samples were harvested for material properties testing at both room and elevated temperatures. As a lower cost and lighter weight alternative to an all-rhenium component, rhenium- coated graphite and carbon-carbon were also evaluated. The rhenium-coated components were thermal-cycle tested to verify that they could withstand the expected thermal loads during service. High-temperature electroforming is based on electrochemical deposition of compact layers of metals onto a mandrel of the desired shape. Mandrels used for electro-deposition of near-net shaped parts are generally fabricated from high-density graphite. The graphite mandrel is easily machined and does not react with the molten electrolyte. For near-net shape components, the inner surface of the electroformed part replicates the polished graphite mandrel. During processing, the mandrel itself becomes the cathode, and scrap or refined refractory metal is the anode. Refractory metal atoms from the anode material are ionized in the molten electrolytic solution, and are deposited onto the cathodic mandrel by electrochemical reduction. Rotation of the mandrel ensures uniform distribution of refractory material. The EL-Form process allows for manufacturing in an inert atmosphere with deposition rates from 0.0004 to 0.002 in./h (10.2 to 50.8 m/h). Thicknesses typically range from microns to greater than 0.5 in. (13 mm). The refractory component produced is fabricated, dependably, to within one micron of the desired tolerances with no shrinkage or distortion as in other refractory metal manufacture techniques. The electroforming process has been used to produce solid, nonporous deposits of rhenium, iridium, niobium, tungsten, and their alloys.

One-step sonochemical synthesis of 1D β-stannous tungstate nanorods: An efficient and excellent electrocatalyst for the selective electrochemical detection of antipsychotic drug chlorpromazine.

PubMed

Kokulnathan, Thangavelu; Kumar, Jeyaraj Vinoth; Chen, Shen-Ming; Karthik, Raj; Elangovan, Arumugam; Muthuraj, Velluchamy

2018-06-01

In the modern world, the contamination of ecosystem by human and veterinary pharmaceutical drugs through the metabolic excretion, improper disposal/industrial waste has been subjected to a hot issue. Therefore, exploitation of exclusive structured material and reliable technique is a necessary task to the precise detection of drugs. With this regards, we made an effort for the fabrication of novel one-dimensional (1D) stannous tungstate nanorods (β-SnW NRs) via simple sonochemical approach and used as an electrochemical sensor for the detection of antipsychotic drug chlorpromazine (CPZ) for the first time. The crystallographic structure, surface topology, elemental compositions and their distributions and ionic states were enquired by different spectroscopic techniques such as XRD, FTIR, SEM, EDS, elemental mapping and XPS analysis. The developed β-SnW NRs/GCE sensor exhibits a rapid and sensitive electrochemical response towards CPZ sensing with wide linear response range (0.01-457 µM), high sensitivity (2.487 µA µM -1  cm -2 ), low detection limit (0.003 µM) and excellent selectivity. Besides, the as-proposed electrochemical sensor was successfully applied to real sample analysis in commercial CPZ drug and biological fluids and the acquired recovery results are quite satisfactory. The proposed sonochemical method for the preparation of β-SnW NRs is low cost, very simple, fast and efficient for sensor applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Studies of electrode structures and dynamics using coherent X-ray scattering and imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

You, H.; Liu, Y.; Ulvestad, A.

2017-08-01

Electrochemical systems studied in situ with advanced surface X-ray scattering techniques are reviewed. The electrochemical systems covered include interfaces of single-crystals and nanocrystals with respect to surface modification, aqueous dissolution, surface reconstruction, and electrochemical double layers. An emphasis will be given on recent results by coherent X-ray techniques such as X-ray photon correlation spectroscopy, Bragg coherent diffraction imaging, and surface ptychography.

APPLICATIONS OF ELECTROCHEMICAL IMMUNOSENSORS TO ENVIRONMENTAL MONITORING

EPA Science Inventory

This paper discusses basic electrochemical immunoassay technology. Factors limiting the practical application of antibodies to anlaytical problems are also presented. It addresses the potential use of immunoassay methods based on electrochemical detection for the analysis of env...

Different Technical Applications of Carbon Nanotubes.

PubMed

Abdalla, S; Al-Marzouki, F; Al-Ghamdi, Ahmed A; Abdel-Daiem, A

2015-12-01

Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

Electro-chemical grinding

NASA Technical Reports Server (NTRS)

Feagans, P. L.

1972-01-01

Electro-chemical grinding technique has rotation speed control, constant feed rates, and contour control. Hypersonic engine parts of nickel alloys can be almost 100% machined, keeping tool pressure at virtual zero. Technique eliminates galling and permits constant surface finish and burr-free interrupted cutting.

A Twice Electrochemical-Etching Method to Fabricate Superhydrophobic-Superhydrophilic Patterns for Biomimetic Fog Harvest.

PubMed

Yang, Xiaolong; Song, Jinlong; Liu, Junkai; Liu, Xin; Jin, Zhuji

2017-08-18

Superhydrophobic-superhydrophilic patterned surfaces have attracted more and more attention due to their great potential applications in the fog harvest process. In this work, we developed a simple and universal electrochemical-etching method to fabricate the superhydrophobic-superhydrophilic patterned surface on metal superhydrophobic substrates. The anti-electrochemical corrosion property of superhydrophobic substrates and the dependence of electrochemical etching potential on the wettability of the fabricated dimples were investigated on Al samples. Results showed that high etching potential was beneficial for efficiently producing a uniform superhydrophilic dimple. Fabrication of long-term superhydrophilic dimples on the Al superhydrophobic substrate was achieved by combining the masked electrochemical etching and boiling-water immersion methods. A long-term wedge-shaped superhydrophilic dimple array was fabricated on a superhydrophobic surface. The fog harvest test showed that the surface with a wedge-shaped pattern array had high water collection efficiency. Condensing water on the pattern was easy to converge and depart due to the internal Laplace pressure gradient of the liquid and the contact angle hysteresis contrast on the surface. The Furmidge equation was applied to explain the droplet departing mechanism and to control the departing volume. The fabrication technique and research of the fog harvest process may guide the design of new water collection devices.

Design and synthesis of hierarchical MnO2 nanospheres/carbon nanotubes/conducting polymer ternary composite for high performance electrochemical electrodes.

PubMed

Hou, Ye; Cheng, Yingwen; Hobson, Tyler; Liu, Jie

2010-07-14

For efficient use of metal oxides, such as MnO(2) and RuO(2), in pseudocapacitors and other electrochemical applications, the poor conductivity of the metal oxide is a major problem. To tackle the problem, we have designed a ternary nanocomposite film composed of metal oxide (MnO(2)), carbon nanotube (CNT), and conducting polymer (CP). Each component in the MnO(2)/CNT/CP film provides unique and critical function to achieve optimized electrochemical properties. The electrochemical performance of the film is evaluated by cyclic voltammetry, and constant-current charge/discharge cycling techniques. Specific capacitance (SC) of the ternary composite electrode can reach 427 F/g. Even at high mass loading and high concentration of MnO(2) (60%), the film still showed SC value as high as 200 F/g. The electrode also exhibited excellent charge/discharge rate and good cycling stability, retaining over 99% of its initial charge after 1000 cycles. The results demonstrated that MnO(2) is effectively utilized with assistance of other components (fFWNTs and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) in the electrode. Such ternary composite is very promising for the next generation high performance electrochemical supercapacitors.

In-vitro biocompatibility and corrosion resistance of electrochemically assembled PPy/TNTA hybrid material for biomedical applications

NASA Astrophysics Data System (ADS)

Simi, V. S.; Satish, Aishwarya; Korrapati, Purna Sai; Rajendran, N.

2018-07-01

Nanostructured hybrid materials composed of inorganic and organic constituents of different chemistry and functionality have attracted wide range of biomedical applications. The uniform electrodeposition of polypyrrole into titania nanotube arrays was achieved by normal pulse voltammetry technique in lithium perchlorate electrolyte by varying the pulse period. The electrochemically assembled polypyrrole/titania nanotube arrays (PPy/TNTA) surface was characterized by structural characterizations including attenuated total reflectance -fourier transform infrared spectroscopy, Raman and X-ray photoelectron spectroscopy analysis. Morphological study carried out by high resolution scanning electron microscopy demonstrates the influence of varying pulse period in achieving the controlled deposition of polypyrrole into the nanotube frame work. Cyclic voltammetry study reveals the electroactive nature of the hybrid material. The contact angle measurements and In-vitro immersion studies in stimulated body fluid hanks' solution were carried out to evaluate the wettability and apatite forming ability of the developed hybrid material. The deposition of polypyrrole enhanced the corrosion resistance of TNTA as evidenced from the lower icorr value observed for PPy/TNTA. The corrosion protection behavior of the hybrid material revealed from the electrochemical impedance spectroscopic studies was clearly noticed from the increase in impedance and maximum phase angle values. Further In-vitro cell culture studies were carried out using MG63 osteoblast cells to evaluate the biocompatibility of the hybrid material. Noticeable improvement in corrosion protection and biocompatibility performance suggest the possible application of PPy/TNTA hybrid material for biomedical applications.

Nano-Electrochemistry and Nano-Electrografting with an Original Combined AFM-SECM

PubMed Central

Ghorbal, Achraf; Grisotto, Federico; Charlier, Julienne; Palacin, Serge; Goyer, Cédric; Demaille, Christophe; Ben Brahim, Ammar

2013-01-01

This study demonstrates the advantages of the combination between atomic force microscopy and scanning electrochemical microscopy. The combined technique can perform nano-electrochemical measurements onto agarose surface and nano-electrografting of non-conducting polymers onto conducting surfaces. This work was achieved by manufacturing an original Atomic Force Microscopy-Scanning ElectroChemical Microscopy (AFM-SECM) electrode. The capabilities of the AFM-SECM-electrode were tested with the nano-electrografting of vinylic monomers initiated by aryl diazonium salts. Nano-electrochemical and technical processes were thoroughly described, so as to allow experiments reproducing. A plausible explanation of chemical and electrochemical mechanisms, leading to the nano-grafting process, was reported. This combined technique represents the first step towards improved nano-processes for the nano-electrografting. PMID:28348337

Rapid Two-Millisecond Interrogation of Electrochemical, Aptamer-Based Sensor Response Using Intermittent Pulse Amperometry.

PubMed

Santos-Cancel, Mirelis; Lazenby, Robert A; White, Ryan J

2018-06-22

In this manuscript, we employ the technique intermittent pulse amperometry (IPA) to interrogate equilibrium and kinetic target binding to the surface of electrochemical, aptamer-based (E-AB) sensors, achieving as fast as 2 ms time resolution. E-AB sensors comprise an electrode surface modified with a flexible nucleic acid aptamer tethered at the 3'-terminus with a redox-active molecule. The introduction of a target changes the conformation and flexibility of the nucleic acid, which alters the charge transfer rate of the appended redox molecule. Typically, changes in charge transfer rate within this class of sensor are monitored via voltammetric methods. Here, we demonstrate that the use of IPA enables the detection of changes in charge transfer rates (i.e., current) at times <100 μs after the application of a potential pulse. Changes in sensor current are quantitatively related to target analyte concentration and can be used to create binding isotherms. Furthermore, the application of IPA enables rapid probing of the electrochemical surface with a time resolution equivalent to as low as twice the applied potential pulse width, not previously demonstrated with traditional voltammetric techniques employed with E-AB sensors (alternating current, square wave, cyclic). To visualize binding, we developed false-color plots analogous to those used in the field of fast-scan cyclic voltammetry. The use of IPA is universal, as demonstrated with two representative small molecule E-AB sensors directed against the aminoglycoside antibiotic tobramycin and adenosine triphosphate (ATP). Intermittent pulse amperometry exhibits an unprecedented sub-microsecond temporal response and is a general method for measuring rapid sensor performance.

Pyrolytic synthesis and characterization of N-doped carbon nanoflakes for electrochemical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savilov, S.V., E-mail: savilov@chem.msu.ru; N.S. Kurnakov Institute of General and Inorganic Chemistry Of Russian Academy of Sciences, Leninsky avenue, 31, Moscow 119991; Arkhipova, E.A.

2015-09-15

Highlights: • Carbon nanoflakes doped with nitrogen were produced by a pyrolytic technique. • Quarternary, pyrrolic and pyridinic types of nitrogen are confirmed by XPS. • Nitrogen content depends on precursor used and temperature processed. • Specific surface area values decrease with increasing of synthesis duration. • N-doped carbon nanoflakes may be suitable for electrochemical applications. - Abstract: Nitrogen doped carbon nanoflakes, which are very important for many electrochemical applications, were synthesized by pyrolysis of nitrogen containing organic compounds over metal oxide template. Acetonitrile, pyridine and butylamine, which are of different volatility were tested as N-containing precursors. Morphology, structure andmore » chemical composition of the as-synthesized materials were investigated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that materials are highly defective and consist of a few malformed graphene layers. X-ray photoelectron spectra reflect the dominant graphitic and pyridinic N-bonding configuration. It was also noted that specific surface area depends on the duration and temperature of the reaction. Increase in duration and temperature led to decrease of the specific surface area from 1000 to 160 m{sup 2}/g, 1170 to 210 m{sup 2}/g and 1180 to 480 m{sup 2}/g for acetonitrile, butylamine and pyridine precursors, respectively.« less

Electrochemical study of quinone redox cycling: A novel application of DNA-based biosensors for monitoring biochemical reactions.

PubMed

Ensafi, Ali A; Jamei, Hamid Reza; Heydari-Bafrooei, Esmaeil; Rezaei, B

2016-10-01

This paper presents the results of an experimental investigation of voltammetric and impedimetric DNA-based biosensors for monitoring biological and chemical redox cycling reactions involving free radical intermediates. The concept is based on associating the amounts of radicals generated with the electrochemical signals produced, using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). For this purpose, a pencil graphite electrode (PGE) modified with multiwall carbon nanotubes and poly-diallydimethlammonium chloride decorated with double stranded fish sperm DNA was prepared to detect DNA damage induced by the radicals generated from a redox cycling quinone (i.e., menadione (MD; 2-methyl-1,4-naphthoquinone)). Menadione was employed as a model compound to study the redox cycling of quinones. A direct relationship was found between free radical production and DNA damage. The relationship between MD-induced DNA damage and free radical generation was investigated in an attempt to identify the possible mechanism(s) involved in the action of MD. Results showed that DPV and EIS were appropriate, simple and inexpensive techniques for the quantitative and qualitative comparisons of different reducing reagents. These techniques may be recommended for monitoring DNA damages and investigating the mechanisms involved in the production of redox cycling compounds. Copyright © 2016 Elsevier B.V. All rights reserved.

In situ electrochemical detection of embryonic stem cell differentiation.

PubMed

Yea, Cheol-Heon; An, Jeung Hee; Kim, Jungho; Choi, Jeong-Woo

2013-06-20

Stem cell sensors have emerged as a promising technique to electrochemically monitor the functional status and viability of stem cells. However, efficient electrochemical analysis techniques are required for the development of effective electrochemical stem cell sensors. In the current study, we report a newly developed electrochemical cyclic voltammetry (CV) system to determine the status of mouse embryonic stem (ES) cells. 1-Naphthly phosphate (1-NP), which was dephosphorylated by alkaline phosphatase into a 1-naphthol on an undifferentiated mouse ES cell, was used as a substrate to electrochemically monitor the differentiation status of mouse ES cells. The peak current in the cyclic voltammetry of 1-NP increased linearly with the concentration of pure 1-NP (R(2)=0.9623). On the other hand, the peak current in the electrochemical responses of 1-NP decreased as the number of undifferentiated ES cells increased. The increased dephosphorylation of 1-NP to 1-naphthol made a decreased electrochemical signal. Non-toxicity of 1-NP was confirmed. In conclusion, the proposed electrochemical analysis system can be applied to an electrical stem cell chip for diagnosis, drug detection and on-site monitoring. Copyright © 2013 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhakaran, Venkateshkumar; Johnson, Grant E.; Wang, Bingbing

Molecular-level understanding of electrochemical processes occurring at electrode-electrolyte interfaces (EEI) is key to the rational development of high-performance and sustainable electrochemical technologies. This article reports the development and first application of solid-state in situ electrochemical probes to study redox and catalytic processes occurring at well-defined EEI generated using soft-landing of mass- and charge-selected cluster ions (SL). In situ electrochemical probes with excellent mass transfer properties are fabricated using carefully-designed nanoporous ionic liquid membranes. SL enables deposition of pure active species that are not obtainable with other techniques onto electrode surfaces with precise control over charge state, composition, and kinetic energy.more » SL is, therefore, a unique tool for studying fundamental processes occurring at EEI. For the first time using an aprotic electrochemical probe, the effect of charge state (PMo12O403-/2-) and the contribution of building blocks of Keggin polyoxometalate (POM) clusters to redox processes are characterized by populating EEI with novel POM anions generated by electrospray ionization and gas phase dissociation. Additionally, a proton conducting electrochemical probe has been developed to characterize the reactive electrochemistry (oxygen reduction activity) of bare Pt clusters (Pt40 ~1 nm diameter), thus demonstrating the capability of the probe for studying reactions in controlled gaseous environments. The newly developed in situ electrochemical probes combined with ion SL provide a versatile method to characterize the EEI in solid-state redox systems and reactive electrochemistry at precisely-defined conditions. This capability will advance molecular-level understanding of processes occurring at EEI that are critical to many energy-related technologies.« less

Printable Electrochemical Biosensors: A Focus on Screen-Printed Electrodes and Their Application

PubMed Central

Yamanaka, Keiichiro; Vestergaard, Mun’delanji C.; Tamiya, Eiichi

2016-01-01

In this review we present electrochemical biosensor developments, focusing on screen-printed electrodes (SPEs) and their applications. In particular, we discuss how SPEs enable simple integration, and the portability needed for on-field applications. First, we briefly discuss the general concept of biosensors and quickly move on to electrochemical biosensors. Drawing from research undertaken in this area, we cover the development of electrochemical DNA biosensors in great detail. Through specific examples, we describe the fabrication and surface modification of printed electrodes for sensitive and selective detection of targeted DNA sequences, as well as integration with reverse transcription-polymerase chain reaction (RT-PCR). For a more rounded approach, we also touch on electrochemical immunosensors and enzyme-based biosensors. Last, we present some electrochemical devices specifically developed for use with SPEs, including USB-powered compact mini potentiostat. The coupling demonstrates the practical use of printable electrode technologies for application at point-of-use. Although tremendous advances have indeed been made in this area, a few challenges remain. One of the main challenges is application of these technologies for on-field analysis, which involves complicated sample matrices. PMID:27775661

Manufacturing the Gas Diffusion Layer for PEM Fuel Cell Using a Novel 3D Printing Technique and Critical Assessment of the Challenges Encountered

PubMed Central

Singamneni, Sarat; Ramos, Maximiano; Al-Jumaily, Ahmed M

2017-01-01

The conventional gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells incorporates a carbon-based substrate, which suffers from electrochemical oxidation as well as mechanical degradation, resulting in reduced durability and performance. In addition, it involves a complex manufacturing process to produce it. The proposed technique aims to resolve both these issues by an advanced 3D printing technique, namely selective laser sintering (SLS). In the proposed work, polyamide (PA) is used as the base powder and titanium metal powder is added at an optimised level to enhance the electrical conductivity, thermal, and mechanical properties. The application of selective laser sintering to fabricate a robust gas diffusion substrate for PEM fuel cell applications is quite novel and is attempted here for the first time. PMID:28773156

Manufacturing the Gas Diffusion Layer for PEM Fuel Cell Using a Novel 3D Printing Technique and Critical Assessment of the Challenges Encountered.

PubMed

Jayakumar, Arunkumar; Singamneni, Sarat; Ramos, Maximiano; Al-Jumaily, Ahmed M; Pethaiah, Sethu Sundar

2017-07-14

The conventional gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells incorporates a carbon-based substrate, which suffers from electrochemical oxidation as well as mechanical degradation, resulting in reduced durability and performance. In addition, it involves a complex manufacturing process to produce it. The proposed technique aims to resolve both these issues by an advanced 3D printing technique, namely selective laser sintering (SLS). In the proposed work, polyamide (PA) is used as the base powder and titanium metal powder is added at an optimised level to enhance the electrical conductivity, thermal, and mechanical properties. The application of selective laser sintering to fabricate a robust gas diffusion substrate for PEM fuel cell applications is quite novel and is attempted here for the first time.

Simultaneous/Selective Detection of Dopamine and Ascorbic Acid at Synthetic Zeolite-Modified/Graphite-Epoxy Composite Macro/Quasi-Microelectrodes

PubMed Central

Ilinoiu, Elida Cristina; Manea, Florica; Serra, Pier Andrea; Pode, Rodica

2013-01-01

The present paper aims to miniaturize a graphite-epoxy and synthetic zeolite-modified graphite-epoxy composite macroelectrode as a quasi-microelectrode aiming in vitro and also, envisaging in vivo simultaneous electrochemical detection of dopamine (DA) and ascorbic acid (AA) neurotransmitters, or DA detection in the presence of AA. The electrochemical behavior and the response of the designed materials to the presence of dopamine and ascorbic acid without any protective membranes were studied by cyclic voltammetry and constant-potential amperometry techniques. The catalytic effect towards dopamine detection was proved for the synthetic zeolite-modified graphite-epoxy composite quasi-microelectrode, allowing increasing the sensitivity and selectivity for this analyte detection, besides a possible electrostatic attraction between dopamine cation and the negative surface of the synthetic zeolite and electrostatic repulsion with ascorbic acid anion. Also, the synthetic zeolite-modified graphite-epoxy composite quasi-microelectrode gave the best electroanalytical parameters for dopamine detection using constant-potential amperometry, the most useful technique for practical applications. PMID:23736851

Microelectrode voltammetry of multi-electron transfers complicated by coupled chemical equilibria: a general theory for the extended square scheme.

PubMed

Laborda, Eduardo; Gómez-Gil, José María; Molina, Angela

2017-06-28

A very general and simple theoretical solution is presented for the current-potential-time response of reversible multi-electron transfer processes complicated by homogeneous chemical equilibria (the so-called extended square scheme). The expressions presented here are applicable regardless of the number of electrons transferred and coupled chemical processes, and they are particularized for a wide variety of microelectrode geometries. The voltammetric response of very different systems presenting multi-electron transfers is considered for the most widely-used techniques (namely, cyclic voltammetry, square wave voltammetry, differential pulse voltammetry and steady state voltammetry), studying the influence of the microelectrode geometry and the number and thermodynamics of the (electro)chemical steps. Most appropriate techniques and procedures for the determination of the 'interaction' between successive transfers are discussed. Special attention is paid to those situations where homogeneous chemical processes, such as protonation, complexation or ion association, affect the electrochemical behaviour of the system by different stabilization of the oxidation states.

Simultaneous/selective detection of dopamine and ascorbic acid at synthetic zeolite-modified/graphite-epoxy composite macro/quasi-microelectrodes.

PubMed

Ilinoiu, Elida Cristina; Manea, Florica; Serra, Pier Andrea; Pode, Rodica

2013-06-03

The present paper aims to miniaturize a graphite-epoxy and synthetic zeolite-modified graphite-epoxy composite macroelectrode as a quasi-microelectrode aiming in vitro and also, envisaging in vivo simultaneous electrochemical detection of dopamine (DA) and ascorbic acid (AA) neurotransmitters, or DA detection in the presence of AA. The electrochemical behavior and the response of the designed materials to the presence of dopamine and ascorbic acid without any protective membranes were studied by cyclic voltammetry and constant-potential amperometry techniques. The catalytic effect towards dopamine detection was proved for the synthetic zeolite-modified graphite-epoxy composite quasi-microelectrode, allowing increasing the sensitivity and selectivity for this analyte detection, besides a possible electrostatic attraction between dopamine cation and the negative surface of the synthetic zeolite and electrostatic repulsion with ascorbic acid anion. Also, the synthetic zeolite-modified graphite-epoxy composite quasi-microelectrode gave the best electroanalytical parameters for dopamine detection using constant-potential amperometry, the most useful technique for practical applications.

Brief review: Preparation techniques of biomass based activated carbon monolith electrode for supercapacitor applications

NASA Astrophysics Data System (ADS)

Taer, Erman; Taslim, Rika

2018-02-01

The synthesis of activated carbon monolith electrode made from a biomass material using the hydrolytic pressure or the pelletization technique of pre-carbonized materials is one of standard reported methods. Several steps such as pre-carbonization, milling, chemical activation, hydraulic press, carbonization, physical activation, polishing and washing need to be accomplished in the production of electrodes by this method. This is relatively a long process that need to be simplified. In this paper we present the standard method and proceed with the introduction to several alternative methods in the synthesis of activated carbon monolith electrodes. The alternative methods were emphasized on the selection of suitable biomass materials. All of carbon electrodes prepared by different methods will be analyzed for physical and electrochemical properties. The density, degree of crystallinity, surface morphology are examples for physical study and specific capacitance was an electrochemical properties that has been analysed. This alternative method has offered a specific capacitance in the range of 10 to 171 F/g.

Smart bi-metallic perovskite nanofibers as selective and reusable sensors of nano-level concentrations of non-steroidal anti-inflammatory drugs.

PubMed

Mohamed, Mona A; Hasan, Menna M; Abdullah, Ibrahim H; Abdellah, Ahmed M; Yehia, Ali M; Ahmed, Nashaat; Abbas, Walaa; Allam, Nageh K

2018-08-01

A strategy for trace-level carbon-based electrochemical sensors is investigated via exploring the interesting properties of BaNb 2 O 6 nanofibers (NFs). Utilizing adsorptive stripping square wave voltammetry (ASSWV), an electrochemical sensing platform was developed based on BaNb 2 O 6 nanofibers-modified carbon paste electrode (CPE) for the sensitive detection of lornoxicam (LOR). Different techniques were used to characterize the fabricated BaNb 2 O 6 perovskite NFs. The obtained data show the feasibility to electro-oxidize LOR and paracetamol (PAR) on the surface of the fabricated sensor. The amount of nanofiber and testing conditions were optimized using response surface methodology and ASSWV technique. The optimized BaNb 2 O 6 /CPE sensor exhibits low detection limit of 6.39 × 10 -10 mol L -1 , even in the presence of the co-formulated drug paracetamol (PAR). The sensor was successfully applied for biological applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Detecting Corrosion Resistance of Coated Steel Rebars by Electrochemical Technique (eis)

NASA Astrophysics Data System (ADS)

Ryou, J.; Shah, S.

Electrochemical impedance spectroscopy (EIS) is one of the electrochemical techniques used in materials science. The present measurements are used to evaluate the corrosion resistance of new types of coated steel rebar used in reinforced concrete. In this study, Si-based coating materials are used and evaluated, because adding Si to metals and alloys, including steel, generally increases their corrosion, oxidation, and erosion resistance. The result suggests that electrochemical impedance spectroscopy may be useful for monitoring corrosion activity on coated steel rebars. Based upon impedance changes, it appears that the silicon powder coating bonds well to the steel, and that the coating has a good performance.

Synthesis and fabrication of porous activated carbon/nano ZnO composite electrode for supercapacitor

NASA Astrophysics Data System (ADS)

P, Shabeeba; Thayyil, Mohammed Shahin; Pillai, M. P.

2017-05-01

Supercapacitors, also called as ultracapacitors, are electrochemical energy-storage devices that exploit the electrostatic interaction between high-surface-area nanoporous electrodes and electrolyte ions that combine properties of conventional batteries and conventional capacitors. A symmetrical ZnO-Activated Carbon (ZAC) electrode supercapacitor have been fabricated in a simple and inexpensive manner. The electrochemical characteristics of fabricated supercapacitor was analyzed using Cyclic Voltammetry (CV), galvanostatic charge discharge technique, and impedance spectroscopy methods. Capacitance of fabricated ZAC electrode were showed capacitance in the range of 60-70 F/g respectively. It has been found that the cells have excellent electro chemical reversibility, capacitive characteristics in electrolyte and stable in cyclings, which is promising for energy storage applications.

Enhanced supercapacitor performances using C-doped porous TiO2 electrodes

NASA Astrophysics Data System (ADS)

Chen, Juanrong; Qiu, Fengxian; Zhang, Ying; Liang, Jianzheng; Zhu, Huijun; Cao, Shunsheng

2015-11-01

Considerable efforts have been paid to develop electrochemical capacitors with energy storage capability in order to meet the demands of multifunctional electronics. Here we report a facile method to fabricate C-doped porous anatase TiO2. This technique involves the preparation of monodisperse cationic polystyrene nanoparticles (CPN), following sequential deposition of tetrabutylorthotitanate (TBT), and directly carbonizing of CPN. Interestingly, during the process of carbonizing CPN, a phase transition of TiO2 will be happened and whist C-doped porous anatase TiO2 is in situ formed. When this porous C-doped TiO2 is used as electrode material to prepare electrochemical capacitor, it manifests a higher capacitance than the commercial P25, effectively broadening it potential for many practical applications.

Nanoscale visualization of redox activity at lithium-ion battery cathodes.

PubMed

Takahashi, Yasufumi; Kumatani, Akichika; Munakata, Hirokazu; Inomata, Hirotaka; Ito, Komachi; Ino, Kosuke; Shiku, Hitoshi; Unwin, Patrick R; Korchev, Yuri E; Kanamura, Kiyoshi; Matsue, Tomokazu

2014-11-17

Intercalation and deintercalation of lithium ions at electrode surfaces are central to the operation of lithium-ion batteries. Yet, on the most important composite cathode surfaces, this is a rather complex process involving spatially heterogeneous reactions that have proved difficult to resolve with existing techniques. Here we report a scanning electrochemical cell microscope based approach to define a mobile electrochemical cell that is used to quantitatively visualize electrochemical phenomena at the battery cathode material LiFePO4, with resolution of ~100 nm. The technique measures electrode topography and different electrochemical properties simultaneously, and the information can be combined with complementary microscopic techniques to reveal new perspectives on structure and activity. These electrodes exhibit highly spatially heterogeneous electrochemistry at the nanoscale, both within secondary particles and at individual primary nanoparticles, which is highly dependent on the local structure and composition.

Electrochemical investigations of advanced materials for microelectronic and energy storage devices

NASA Astrophysics Data System (ADS)

Goonetilleke, Pubudu Chaminda

A broad range of electrochemical techniques are employed in this work to study a selected set of advanced materials for applications in microelectronics and energy storage devices. The primary motivation of this study has been to explore the capabilities of certain modern electrochemical techniques in a number of emerging areas of material processing and characterization. The work includes both aqueous and non-aqueous systems, with applications in two rather general areas of technology, namely microelectronics and energy storage. The sub-systems selected for investigation are: (i) Electrochemical mechanical and chemical mechanical planarization (ECMP and CMP, respectively), (ii) Carbon nanotubes in combination with room temperature ionic liquids (ILs), and (iii) Cathode materials for high-performance Li ion batteries. The first group of systems represents an important building block in the fabrication of microelectronic devices. The second and third groups of systems are relevant for new energy storage technologies, and have generated immense interests in recent years. A common feature of these different systems is that they all are associated with complex surface reactions that dictate the performance of the devices based on them. Fundamental understanding of these reactions is crucial to further development and expansion of their associated technologies. It is the complex mechanistic details of these surface reactions that we address using a judicious combination of a number of state of the art electrochemical techniques. The main electrochemical techniques used in this work include: (i) Cyclic voltammetry (CV) and slow scan cyclic voltammetry (SSCV, a special case of CV); (ii) Galvanostatic (or current-controlled) measurements; (iii) Electrochemical impedance spectroscopy (EIS), based on two different methodologies, namely, Fourier transform EIS (FT-EIS, capable of studying fast reaction kinetics in a time-resolved mode), and EIS using frequency response analysis (employed to study slow reactions such as solid state diffusion of Li). The designs of both the experimental equipment and the control variables change for studying the different aqueous and non-aqueous systems. The protocols for data analysis also change depending on the systems. In addition, it often becomes necessary to combine different aspects of the different experimental methods to obtain the necessary information about the system(s) under study. The experimental strategies and the associated theoretical considerations for developing these strategies are discussed in appropriate contexts of this work. CNT electrodes in combination with IL electrolytes are potentially important for electrochemical super-capacitors. We have carried out electrochemical investigation of such a system involving a paper-electrode of multiwall CNT in the IL of 1-Ethyl-3-methyl imidazolium ethylsulfate (EMIM-EtSO4). Our study concentrated on the analytical aspects of cyclic voltammetry (CV) to probe the double layer capacitance of these relatively unconventional systems. (that involve rather large charge-discharge time constants). Both theoretical and experimental aspects of CV for such systems have been discussed, focusing in particular, on the effects of faradaic side-reactions, electrolyte resistance and voltage scan speeds. The results have been analyzed using an electrode equivalent circuit model, demonstrating a method to account for the typical artifacts expected in CV of CNT-IL interfaces. Chemical-mechanical planarization (CMP) of copper has now become an integral part of modern semiconductor fabrication technology. Recently, electrochemical-mechanical planarization (ECMP) has emerged as a possible extension of CMP, where through voltage-activated removal of Cu surface layers, one can substantially minimize the down-force necessary for mechanical polishing However, the detailed electrochemical factors that are central to designing efficient abrasive-free electrolytes for ECMP are not clearly understood at the present time. The present work has addressed this issue by studying the relative electrochemical effects of selected different chemical additives. Controlling the surface reactions (that is controlling the voltage-induced material removal) in ECMP requires a carefully designed combination of a number of electrochemical input variables (voltage activation program and electrolyte composition). We have studied the main experimental factors for designing these parameters, using triangular and rectangular-voltage-pulse modulated dissolution of Cu in electrolytes of different chemical compositions. Applications of rechargeable Li ion batteries have considerably expanded in recent years. As a result, research activities involving material-fabrication and characterization for these batteries also have expanded during this period. The importance of studying these specific materials lies in the fact that the cathode plays a major role in its contribution to the battery performance LiMn2O4 cathodes are being considered for next generation of Li ion batteries. The current work focuses on a specific problem commonly associated with Li cathode systems, namely surface film formation on the cathodes. LiMn2O4 cathodes tend to develop native surface films in carbonate electrolytes. By combining D.C. SSCV with A.C. EIS, we have studied how these films would react with an electrolyte of LiBF4 in ethylene and diethyl carbonates. We have demonstrated that such reactions could affect the measurement of the characteristic electrochemical parameters of the cathode, namely the intercalation capacitance, initial capacity-loss, coulometric titration profiles, and the solid state diffusion coefficient of Li+. A generalized framework for data analysis, based on the considerations of electrode equivalent circuits, has been used to combine the results of the D.C. and A.C. measurements.

Hydrothermal synthesis of reduced graphene sheets/Fe2O3 nanorods composites and their enhanced electrochemical performance for supercapacitors

NASA Astrophysics Data System (ADS)

Yang, Wanlu; Gao, Zan; Wang, Jun; Wang, Bin; Liu, Lianhe

2013-06-01

Reduced graphene nanosheets/Fe2O3 nanorods (GNS/Fe2O3) composite has been fabricated by a hydrothermal route for supercapacitor electrode materials. The obtained GNS/Fe2O3 composite formed a uniform structure with the Fe2O3 nanorods grew on the graphene surface and/or filled between the graphene sheets. The electrochemical performances of the GNS/Fe2O3 hybrid supercapacitor were tested by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge tests in 6 M KOH electrolyte. Comparing with the pure Fe2O3 electrode, GNS/Fe2O3 composite electrode exhibits an enhanced specific capacitance of 320 F g-1 at 10 mA cm-2 and an excellent cycle-ability with capacity retention of about 97% after 500 cycles. The simple and cost-effective preparation technique of this composite with good capacitive behavior encourages its potential commercial application.

Nano-engineering of three-dimensional core/shell nanotube arrays for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Grote, Fabian; Wen, Liaoyong; Lei, Yong

2014-06-01

Large-scale arrays of core/shell nanostructures are highly desirable to enhance the performance of supercapacitors. Here we demonstrate an innovative template-based fabrication technique with high structural controllability, which is capable of synthesizing well-ordered three-dimensional arrays of SnO2/MnO2 core/shell nanotubes for electrochemical energy storage in supercapacitor applications. The SnO2 core is fabricated by atomic layer deposition and provides a highly electrical conductive matrix. Subsequently a thin MnO2 shell is coated by electrochemical deposition onto the SnO2 core, which guarantees a short ion diffusion length within the shell. The core/shell structure shows an excellent electrochemical performance with a high specific capacitance of 910 F g-1 at 1 A g-1 and a good rate capability of remaining 217 F g-1 at 50 A g-1. These results shall pave the way to realize aqueous based asymmetric supercapacitors with high specific power and high specific energy.

Nanoplasmonic Biosensor Using Localized Surface Plasmon Resonance Spectroscopy for Biochemical Detection.

PubMed

Zhang, Diming; Zhang, Qian; Lu, Yanli; Yao, Yao; Li, Shuang; Liu, Qingjun

2017-01-01

Localized surface plasmon resonance (LSPR) associated with metal nanostructures has developed into a highly useful sensor technique. Optical LSPR spectroscopy of nanostructures often shows sharp absorption and scattering peaks, which can be used to probe several bio-molecular interactions. Here, we report nanoplasmonic biosensors using LSPR on nanocup arrays (nanoCA) to recognize bio-molecular binding for biochemical detection. These sensors can be modified to quantify binding of small molecules to proteins for odorant and explosive detections. Electrochemical LSPR biosensors can also be designed by coupling electrochemistry and LSPR spectroscopy measurements. Multiple sensing information can be obtained and electrochemical LSPR property can be investigated for biosensors. In some applications, the electrochemical LSPR biosensor can be used to quantify immunoreactions and enzymatic activity. The biosensors exhibit better performance than those of conventional optical LSPR measurements. With multi-transducers, the nanoplasmonic biosensor can provide a promising approach for bio-detection in environmental monitoring, healthcare diagnostics, and food quality control.

Influence of Pore Characteristics on Electrochemical and Biological Behavior of Ti Foams

NASA Astrophysics Data System (ADS)

Salehi, Akram; Barzegar, Faezeh; Amini Mashhadi, Hossein; Nokhasteh, Samira; Abravi, Mohammad Sadegh

2017-08-01

This study reports on titanium (Ti) foams produced using the powder metallurgy technique. During the investigation, the cross-sectional area and perimeter distributions of the pores within the foam were measured. Metallographic image processing analysis software combined with scanning electron microscopic images demonstrated that the pore size and circularity were affected by varying the volume percentage of the space-holder material. The corrosion resistance was investigated using electrochemical impedance spectroscopy and cyclic polarization tests. MG-63 osteoblast-like cells were used to study the biocompatibility and to evaluate the cell attachment, viability, and alkaline phosphatase activity. Analytical results indicated that 50 and 60 vol.% samples were suitable for biomedical applications. Because of the high degree of interconnectivity in the 60 and 70% porosity samples, the electrochemical parameters produced similar results. The corrosion rate of the porous samples showed that the amount of dissolved Ti was at an acceptable level that can be ejected by the body. Applying a fluoridated hydroxyapatite coating significantly increased the osteoblast cell functions on the porous surface.

Electric Arc and Electrochemical Surface Texturing Technologies

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Rutledge, Sharon K.; Snyder, Scott A.

1997-01-01

Surface texturing of conductive materials can readily be accomplished by means of a moving electric arc which produces a plasma from the environmental gases as well as from the vaporized substrate and arc electrode materials. As the arc is forced to move across the substrate surface, a condensate from the plasma re-deposits an extremely rough surface which is intimately mixed and attached to the substrate material. The arc textured surfaces produce greatly enhanced thermal emittance and hold potential for use as high temperature radiator surfaces in space, as well as in systems which use radiative heat dissipation such as computer assisted tomography (CAT) scan systems. Electrochemical texturing of titanium alloys can be accomplished by using sodium chloride solutions along with ultrasonic agitation to produce a random distribution of craters on the surface. The crater size and density can be controlled to produce surface craters appropriately sized for direct bone in-growth of orthopaedic implants. Electric arc texturing and electrochemical texturing techniques, surface properties and potential applications will be presented.

Electrochemical DNA Hybridization Sensors Based on Conducting Polymers

PubMed Central

Rahman, Md. Mahbubur; Li, Xiao-Bo; Lopa, Nasrin Siraj; Ahn, Sang Jung; Lee, Jae-Joon

2015-01-01

Conducting polymers (CPs) are a group of polymeric materials that have attracted considerable attention because of their unique electronic, chemical, and biochemical properties. This is reflected in their use in a wide range of potential applications, including light-emitting diodes, anti-static coating, electrochromic materials, solar cells, chemical sensors, biosensors, and drug-release systems. Electrochemical DNA sensors based on CPs can be used in numerous areas related to human health. This review summarizes the recent progress made in the development and use of CP-based electrochemical DNA hybridization sensors. We discuss the distinct properties of CPs with respect to their use in the immobilization of probe DNA on electrode surfaces, and we describe the immobilization techniques used for developing DNA hybridization sensors together with the various transduction methods employed. In the concluding part of this review, we present some of the challenges faced in the use of CP-based DNA hybridization sensors, as well as a future perspective. PMID:25664436

Fabrication and Characterization of Thin Film Nickel Hydroxide Electrodes for Micropower Applications.

PubMed

Falahati, Hamid; Kim, Edward; Barz, Dominik P J

2015-06-17

The utilization of micropower sources is attractive in portable microfluidic devices where only low-power densities and energy contents are required. In this work, we report on the microfabrication of patterned α-Ni(OH)2 films on glass substrates which can be used for rechargeable microbatteries as well as for microcapacitors. A multilayer deposition technique is developed based on e-beam evaporation, ultraviolet lithography, and electroplating/electrodeposition which creates thin-film electrodes that are patterned with arrays of micropillars. The morphology and the structure of the patterned electrode films are characterized by employing field emission scanning electron microscopy. The chemical (elemental) composition is investigated by using X-ray diffraction and X-ray photoelectron spectroscopy. Finally, cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge measurements are used to evaluate the electrochemical performance of the patterned thin film electrodes compared to patternless electrodes. We observe that patterning of the electrodes results in significantly improved stability and, thus, longer endurance while good electrochemical performance is maintained.

Biosensing with Paper-Based Miniaturized Printed Electrodes-A Modern Trend.

PubMed

Silveira, Célia M; Monteiro, Tiago; Almeida, Maria Gabriela

2016-09-28

From the bench-mark work on microfluidics from the Whitesides's group in 2007, paper technology has experienced significant growth, particularly regarding applications in biomedical research and clinical diagnostics. Besides the structural properties supporting microfluidics, other advantageous features of paper materials, including their versatility, disposability and low cost, show off the great potential for the development of advanced and eco-friendly analytical tools. Consequently, paper was quickly employed in the field of electrochemical sensors, being an ideal material for producing custom, tailored and miniaturized devices. Stencil-, inkjet-, or screen-printing are the preferential techniques for electrode manufacturing. Not surprisingly, we witnessed a rapid increase in the number of publications on paper based screen-printed sensors at the turn of the past decade. Among the sensing strategies, various biosensors, coupling electrochemical detectors with biomolecules, have been proposed. This work provides a critical review and a discussion on the future progress of paper technology in the context of miniaturized printed electrochemical biosensors.

Visualization of electrochemically driven solid-state phase transformations using operando hard X-ray spectro-imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Linsen; Chen-Wiegart, Yu-chen Karen; Wang, Jiajun

In situ techniques with high temporal, spatial and chemical resolution are key to understand ubiquitous solid-state phase transformations, which are crucial to many technological applications. Hard X-ray spectro-imaging can visualize electrochemically driven phase transformations but demands considerably large samples with strong absorption signal so far. Here we show a conceptually new data analysis method to enable operando visualization of mechanistically relevant weakly absorbing samples at the nanoscale and study electrochemical reaction dynamics of iron fluoride, a promising high-capacity conversion cathode material. In two specially designed samples with distinctive microstructure and porosity, we observe homogeneous phase transformations during both discharge andmore » charge, faster and more complete Li-storage occurring in porous polycrystalline iron fluoride, and further, incomplete charge reaction following a pathway different from conventional belief. In conclusion, these mechanistic insights provide guidelines for designing better conversion cathode materials to realize the promise of high-capacity lithium-ion batteries.« less

Biosensing with Paper-Based Miniaturized Printed Electrodes–A Modern Trend

PubMed Central

Silveira, Célia M.; Monteiro, Tiago; Almeida, Maria Gabriela

2016-01-01

From the bench-mark work on microfluidics from the Whitesides’s group in 2007, paper technology has experienced significant growth, particularly regarding applications in biomedical research and clinical diagnostics. Besides the structural properties supporting microfluidics, other advantageous features of paper materials, including their versatility, disposability and low cost, show off the great potential for the development of advanced and eco-friendly analytical tools. Consequently, paper was quickly employed in the field of electrochemical sensors, being an ideal material for producing custom, tailored and miniaturized devices. Stencil-, inkjet-, or screen-printing are the preferential techniques for electrode manufacturing. Not surprisingly, we witnessed a rapid increase in the number of publications on paper based screen-printed sensors at the turn of the past decade. Among the sensing strategies, various biosensors, coupling electrochemical detectors with biomolecules, have been proposed. This work provides a critical review and a discussion on the future progress of paper technology in the context of miniaturized printed electrochemical biosensors. PMID:27690119

Visualization of electrochemically driven solid-state phase transformations using operando hard X-ray spectro-imaging

DOE PAGES

Li, Linsen; Chen-Wiegart, Yu-chen Karen; Wang, Jiajun; ...

2015-04-20

In situ techniques with high temporal, spatial and chemical resolution are key to understand ubiquitous solid-state phase transformations, which are crucial to many technological applications. Hard X-ray spectro-imaging can visualize electrochemically driven phase transformations but demands considerably large samples with strong absorption signal so far. Here we show a conceptually new data analysis method to enable operando visualization of mechanistically relevant weakly absorbing samples at the nanoscale and study electrochemical reaction dynamics of iron fluoride, a promising high-capacity conversion cathode material. In two specially designed samples with distinctive microstructure and porosity, we observe homogeneous phase transformations during both discharge andmore » charge, faster and more complete Li-storage occurring in porous polycrystalline iron fluoride, and further, incomplete charge reaction following a pathway different from conventional belief. In conclusion, these mechanistic insights provide guidelines for designing better conversion cathode materials to realize the promise of high-capacity lithium-ion batteries.« less

ELECTROCHEMICAL TECHNIQUE FOR TNT USING DISPOSABLE SCREEN-PRINTED ELECTRODE

EPA Science Inventory

Screen-printed thick film electrodes are demonstrated as voltammetric sensors for measurement of 2,4,6-trinitrotoluene (TNT). The square wave voltammetric (SWV) scan technique is used to measure TNT in as little as 50 uL sample volumes. This electrochemical assay is coupled ...

Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode.

PubMed

Kalambate, Pramod K; Rawool, Chaitali R; Karna, Shashi P; Srivastava, Ashwini K

2016-12-01

A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (Ip) current for MM is found to be rectilinear in the range 4.0×10(-8)-2.0×10(-5)M with a detection limit of 7.1×10(-9)M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. Copyright © 2016. Published by Elsevier B.V.

Evaluation of Carbon Anodes for Rechargeable Lithium Cells

NASA Technical Reports Server (NTRS)

Huang, C-K.; Surampudi, S.; Attia, A.; Halpert, G.

1993-01-01

Both liquid phase intercalation technique and electrochemical intercalation technique were examined for the Li-carbon material preparation. The electrochemical techniques include a intermittent discharge method and a two step method. These two electrochemical techniques can ensure to achieve the maximum reversible Li capacity for common commercially available carbon materials. The carbon materials evaluated by the intercalacation method includes: pitch coke, petroleum cole, PAN fiber and graphite materials. Their reversible Li capacity were determined and compared. In this paper, we also demonstrate the importance of EPDM binder composition in the carbon electrode. Our results indicated that it can impact the Li intercalation and de-intercalation capacity in carbon materials. Finally, two possibilities that may help explain the capacity degradation during practical cell cycling were proposed.

Bioelectrochemical interface engineering: toward the fabrication of electrochemical biosensors, biofuel cells, and self-powered logic biosensors.

PubMed

Zhou, Ming; Dong, Shaojun

2011-11-15

Over the past decade, researchers have devoted considerable attention to the integration of living organisms with electronic elements to yield bioelectronic devices. Not only is the integration of DNA, enzymes, or whole cells with electronics of scientific interest, but it has many versatile potential applications. Researchers are using these ideas to fabricate biosensors for analytical applications and to assemble biofuel cells (BFCs) and biomolecule-based devices. Other research efforts include the development of biocomputing systems for information processing. In this Account, we focus on our recent progress in engineering at the bioelectrochemical interface (BECI) for the rational design and construction of important bioelectronic devices, ranging from electrochemical (EC-) biosensors to BFCs, and self-powered logic biosensors. Hydrogels and sol-gels provide attractive materials for the immobilization of enzymes because they make EC-enzyme biosensors stable and even functional in extreme environments. We use a layer-by-layer (LBL) self-assembly technique to fabricate multicomponent thin films on the BECI at the nanometer scale. Additionally, we demonstrate how carbon nanomaterials have paved the way for new and improved EC-enzyme biosensors. In addition to the widely reported BECI-based electrochemical impedance spectroscopy (EIS)-type aptasensors, we integrate the LBL technique with our previously developed "solid-state probe" technique for redox probes immobilization on electrode surfaces to design and fabricate BECI-based differential pulse voltammetry (DPV)-type aptasensors. BFCs can directly harvest energy from ambient biofuels as green energy sources, which could lead to their application as simple, flexible, and portable power sources. Porous materials provide favorable microenvironments for enzyme immobilization, which can enhance BFC power output. Furthermore, by introducing aptamer-based logic systems to BFCs, such systems could be applied as self-powered and intelligent aptasensors for the logic detection. We have developed biocomputing keypad lock security systems which can be also used for intelligent medical diagnostics. BECI engineering provides a simple but effective approach toward the design and fabrication of EC-biosensors, BFCs, and self-powered logic biosensors, which will make essential contributions in the development of creative and practical bioelectronic devices. The exploration of novel interface engineering applications and the creation of new fabrication concepts or methods merit further attention.

One pot electrochemical synthesis of polymer/CNT/metal nanoparticles for fuel cell applications

NASA Astrophysics Data System (ADS)

Ventrapragada, Lakshman; Zhu, Jingyi; Karakaya, Mehmet; Podila, Ramakrishna; Rao, Apparao; Clemson Nanomaterials center Team

Carbon nanotubes (CNTs) have become a key player in the design of materials for energy applications. They gained their popularity in industrial and scientific research due to their unique properties like excellent conductivity, high surface area, etc. Here we used chemical vapor deposition (CVD) to synthesize two types of CNTs namely, helically coiled CNTs and vertically aligned CNTs. These CNTs were subsequently used to make composites with conducting polymers and metal nanoparticles. One pot electrochemical synthesis was designed to electropolymerize aniline, pyrrole etc. on the surface of the electrode with simultaneous deposition of platinum and gold metal nanoparticles, and CNTs in the polymer matrix. The as synthesized composite materials were characterized with scanning electron microscope for surface morphology and spectroscopic techniques like Raman, UV-Vis for functionality. These were used to study electrocatalytic oxidation of methanol and ethanol for alkaline fuel cell applications. Electrodes fabricated from these composites not only showed good kinetics but also exhibited excellent stability. Uniqueness of this composite lies in its simple two step synthesis and it doesn't involve any surfactants unlike conventional chemical synthesis routes.

Electrochemical detection of Hg (II) ions using EDTA-PANI/SWNTs nanocomposite modified SS electrode

NASA Astrophysics Data System (ADS)

Deshmukh, M. A.; Patil, H. K.; Shirsat, M. D.; Ramanavicius, A.

2017-05-01

Detection of Hg (II) ions using EDTA modified polyaniline (PANI) and single walled carbon nanotubes (SWNTs) nanocomposite (PANI/SWNTs) was performed electrochemically via cyclic voltammetry (CV) technique. Dodecyl benzene sulphonic next step, PANI/SWNTs nanocomposite was modified acid sodium salt (DBSA) was used as a surfactant during this synthesis to get uniform suspension SWNTs. In the by EDTA solution containing crosslinking agent 1-ethyl-3(3-(dimethylamino) propyl) - carbodiimide (EDC) utilizing dip coating technique. The sensitivity of EDTA modified PANI/SWNTs nanocomposite towards Hg (II) ions was investigated. Differential pulse voltammetry (DPV) technique was applied for the electrochemical detection of Hg (II) ions.

Polyaniline nanowires-gold nanoparticles hybrid network based chemiresistive hydrogen sulfide sensor

NASA Astrophysics Data System (ADS)

Shirsat, Mahendra D.; Bangar, Mangesh A.; Deshusses, Marc A.; Myung, Nosang V.; Mulchandani, Ashok

2009-02-01

We report a sensitive, selective, and fast responding room temperature chemiresistive sensor for hydrogen sulfide detection and quantification using polyaniline nanowires-gold nanoparticles hybrid network. The sensor was fabricated by facile electrochemical technique. Initially, polyaniline nanowires with a diameter of 250-320 nm bridging the gap between a pair of microfabricated gold electrodes were synthesized using templateless electrochemical polymerization using a two step galvanostatic technique. Polyaniline nanowires were then electrochemically functionalized with gold nanoparticles using cyclic voltammetry technique. These chemiresistive sensors show an excellent limit of detection (0.1 ppb), wide dynamic range (0.1-100 ppb), and very good selectivity and reproducibility.

Sealed nickel cadmium batteries

NASA Astrophysics Data System (ADS)

Raudszus, W.; Kiehne, H. A.; Cloke, F. R.

1982-10-01

The design, manufacture, and application of maintenance-free sealed NiCd batteries are surveyed. The principles of electrochemical power supplies and the history of the development of NiCd cells are reviewed. The batteries produced by Varta Batterie AG are presented; topics discussed include design parameters, electrical and physical characteristics, performance under adverse conditions, type range, production, and quality control. Application techniques, including cell-type choice, charging units and charging circuits, and the construction of standby power supplies, are considered, with reference to national and international standards of performance and classification. No individual items are abstracted in this volume

Nanostructured MnO2 as Electrode Materials for Energy Storage

PubMed Central

Mauger, Alain

2017-01-01

Manganese dioxides, inorganic materials which have been used in industry for more than a century, now find great renewal of interest for storage and conversion of energy applications. In this review article, we report the properties of MnO2 nanomaterials with different morphologies. Techniques used for the synthesis, structural, physical properties, and electrochemical performances of periodic and aperiodic frameworks are discussed. The effect of the morphology of nanosized MnO2 particles on their fundamental features is evidenced. Applications as electrodes in lithium batteries and supercapacitors are examined. PMID:29149066

Electrochemical Processes Enhanced by Acoustic Liquid Manipulation

NASA Technical Reports Server (NTRS)

Oeftering, Richard C.

2004-01-01

Acoustic liquid manipulation is a family of techniques that employ the nonlinear acoustic effects of acoustic radiation pressure and acoustic streaming to manipulate the behavior of liquids. Researchers at the NASA Glenn Research Center are exploring new methods of manipulating liquids for a variety of space applications, and we have found that acoustic techniques may also be used in the normal Earth gravity environment to enhance the performance of existing fluid processes. Working in concert with the NASA Commercial Technology Office, the Great Lakes Industrial Technology Center, and Alchemitron Corporation (Elgin, IL), researchers at Glenn have applied nonlinear acoustic principles to industrial applications. Collaborating with Alchemitron Corporation, we have adapted the devices to create acoustic streaming in a conventional electroplating process.

Electrochemically Controlled Reconstitution of Immobilized Ferritins for Bioelectronic Applications

NASA Technical Reports Server (NTRS)

Kim, Jae-Woo; Choi, Sang H.; Lillehei, Peter T.; Chu, Sang-Hong; King, Glen C.; Watt, Gerald D.

2007-01-01

Site-specific reconstituted nanoparticles were fabricated via electrochemically-controlled biomineralization through the immobilization of biomolecules. The work reported herein includes the immobilization of ferritin with various surface modifications, the electrochemical biomineralization of ferritins with different inorganic cores, and the electrocatalytic reduction of oxygen on the reconstituted Pt-cored ferritins. Protein immobilization on the substrate is achieved by anchoring ferritins with dithiobis-N-succinimidyl propionate (DTSP). A reconstitution process of site-specific electrochemical biomineralization with a protein cage loads ferritins with different core materials. The ferritin acts as a nano-scale template, a biocompatible cage, and a separator between the nanoparticles. This first demonstration of electrochemically controlled site-specific reconstitution of biomolecules provides a new tool for biomineralization and opens the way to produce the bio-templated nanoparticles by electrochemical control. The nanosized platinum-cored ferritins on gold displayed good catalytic activity for the electrochemical reduction of oxygen, which is applicable to biofuel cell applications. This results in a smaller catalyst loading on the electrodes for fuel cells or other bioelectronic devices.

Simultaneous Interfacial Reactivity and Topography Mapping with Scanning Ion Conductance Microscopy.

PubMed

Momotenko, Dmitry; McKelvey, Kim; Kang, Minkyung; Meloni, Gabriel N; Unwin, Patrick R

2016-03-01

Scanning ion conductance microscopy (SICM) is a powerful technique for imaging the topography of a wide range of materials and interfaces. In this report, we develop the use and scope of SICM, showing how it can be used for mapping spatial distributions of ionic fluxes due to (electro)chemical reactions occurring at interfaces. The basic idea is that there is a change of ion conductance inside a nanopipet probe when it approaches an active site, where the ionic composition is different to that in bulk solution, and this can be sensed via the current flow in the nanopipet with an applied bias. Careful tuning of the tip potential allows the current response to be sensitive to either topography or activity, if desired. Furthermore, the use of a distance modulation SICM scheme allows reasonably faithful probe positioning using the resulting ac response, irrespective of whether there is a reaction at the interface that changes the local ionic composition. Both strategies (distance modulation or tuned bias) allow simultaneous topography-activity mapping with a single channel probe. The application of SICM reaction imaging is demonstrated on several examples, including voltammetric mapping of electrocatalytic reactions on electrodes and high-speed electrochemical imaging at rates approaching 4 s per image frame. These two distinct approaches provide movies of electrochemical current as a function of potential with hundreds of frames (images) of surface reactivity, to reveal a wealth of spatially resolved information on potential- (and time) dependent electrochemical phenomena. The experimental studies are supported by detailed finite element method modeling that places the technique on a quantitative footing.

Electrochemical impedance spectroscopy based MEMS sensors for phthalates detection in water and juices

NASA Astrophysics Data System (ADS)

Zia, Asif I.; Mohd Syaifudin, A. R.; Mukhopadhyay, S. C.; Yu, P. L.; Al-Bahadly, I. H.; Gooneratne, Chinthaka P.; Kosel, Jǘrgen; Liao, Tai-Shan

2013-06-01

Phthalate esters are ubiquitous environmental and food pollutants well known as endocrine disrupting compounds (EDCs). These developmental and reproductive toxicants pose a grave risk to the human health due to their unlimited use in consumer plastic industry. Detection of phthalates is strictly laboratory based time consuming and expensive process and requires expertise of highly qualified and skilled professionals. We present a real time, non-invasive, label free rapid detection technique to quantify phthalates' presence in deionized water and fruit juices. Electrochemical impedance spectroscopy (EIS) technique applied to a novel planar inter-digital (ID) capacitive sensor plays a vital role to explore the presence of phthalate esters in bulk fluid media. The ID sensor with multiple sensing gold electrodes was fabricated on silicon substrate using micro-electromechanical system (MEMS) device fabrication technology. A thin film of parylene C polymer was coated as a passivation layer to enhance the capacitive sensing capabilities of the sensor and to reduce the magnitude of Faradic current flowing through the sensor. Various concentrations, 0.002ppm through to 2ppm of di (2-ethylhexyl) phthalate (DEHP) in deionized water, were exposed to the sensing system by dip testing method. Impedance spectra obtained was analysed to determine sample conductance which led to consequent evaluation of its dielectric properties. Electro-chemical impedance spectrum analyser algorithm was employed to model the experimentally obtained impedance spectra. Curve fitting technique was applied to deduce constant phase element (CPE) equivalent circuit based on Randle's equivalent circuit model. The sensing system was tested to detect different concentrations of DEHP in orange juice as a real world application. The result analysis indicated that our rapid testing technique is able to detect the presence of DEHP in all test samples distinctively.

Application of poly (p-phenylene oxide) as blocking layer to reduce self-discharge in supercapacitors

NASA Astrophysics Data System (ADS)

Tevi, Tete; Yaghoubi, Houman; Wang, Jing; Takshi, Arash

2013-11-01

Supercapacitors are electrochemical energy storage devices with high power density. However, application of supercapacitors is limited mainly due to their high leakage current. In this work, application of an ultra-thin layer of electrodeposited poly (p-phenylene oxide) (PPO) has been investigated as a blocking layer to reduce the leakage current. The polymer was first deposited on a glassy carbon electrode. The morphology of the film was studied by atomic force microscopy (AFM), and the film thickness was estimated to be ˜1.5 nm by using the electrochemical impedance spectroscopy (EIS) technique. The same deposition method was applied to coat the surface of the activated carbon electrodes of a supercapacitor with PPO. The specific capacitance, the leakage current, and the series resistance were measured in two devices with and without the blocking layer. The results demonstrate that the application of the PPO layer reduced the leakage current by ˜78%. However, the specific capacitance was decreased by ˜56%, when the blocking layer was applied. Due to the lower rate of self-discharge, the suggested approach can be applied to fabricate devices with longer charge storage time.

Stress evolution in elastic-plastic electrodes during electrochemical processes: A numerical method and its applications

NASA Astrophysics Data System (ADS)

Wen, Jici; Wei, Yujie; Cheng, Yang-Tse

2018-07-01

Monitoring in real time the stress state in high capacity electrodes during charge-discharge processes is pivotal to the performance assessment and structural optimization of advanced batteries. The wafer curvature measurement technique broadly employed in thin-film industry, together with stress analysis using the Stoney equation, has been successfully adopted to measure in situ the stress in thin film electrodes. How large plastic deformation or interfacial delamination during electrochemical cycles in such electrodes affects the applicability of Stoney equation remains unclear. Here we develop a robust electrochemical-mechanical coupled numerical procedure to investigate the influence of large plastic deformation and interfacial failure on the measured stress in thin film electrodes. We identify how the constitutive behavior of electrode materials and film-substrate interfacial properties affect the measured stress-capacity curves of electrodes, and hence establish the relationship of electrode material parameters with the characteristics of stress-capacity curves. Using Li-ions batteries as examples, we show that plastic deformation and interfacial delamination account for the asymmetric stress-capacity loops seen in in situ stress measurements. The methods used here, along with the finite-element code in the supplementary material, may be used to model the electrode behavior as a function of the state of charge.

4D nano-tomography of electrochemical energy devices using lab-based X-ray imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heenan, T. M. M.; Finegan, D. P.; Tjaden, B.

Electrochemical energy devices offer a variety of alternate means for low-carbon, multi-scale energy conversion and storage. Reactions in these devices are supported by electrodes with characteristically complex microstructures. To meet the increasing capacity and lifetime demands across a range of applications, it is essential to understand microstructural evolutions at a cell and electrode level which are thought to be critical aspects influencing material and device lifetime and performance. X-ray computed tomography (CT) has become a highly employed method for non-destructive characterisation of such microstructures with high spatial resolution. However, sub-micron resolutions present significant challenges for sample preparation and handling particularlymore » in 4D studies, (three spatial dimensions plus time). Here, microstructural information is collected from the same region of interest within two electrode materials: a solid oxide fuel cell and the positive electrode from a lithium-ion battery. Using a lab-based X-ray instrument, tomograms with sub-micron resolutions were obtained between thermal cycling. The intricate microstructural evolutions captured within these two materials provide model examples of 4D X-ray nano-CT capabilities in tracking challenging degradation mechanisms. This technique is valuable in the advancement of electrochemical research as well as broader applications for materials characterisation.« less

In Situ Mass Spectrometric Monitoring of the Dynamic Electrochemical Process at the Electrode–Electrolyte Interface: a SIMS Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhaoying; Zhang, Yanyan; Liu, Bingwen

The in situ molecular characterization of reaction intermediates and products at electrode-electrolyte interfaces is central to mechanistic studies of complex electrochemical processes, yet a great challenge. The coupling of electrochemistry (EC) and mass spectrometry (MS) has seen rapid development and found broad applicability in tackling challenges in analytical and bioanalytical chemistry. However, few truly in situ and real-time EC-MS studies have been reported at electrode-electrolyte interfaces. An innovative EC-MS coupling method named in situ liquid secondary ion mass spectrometry (SIMS) was recently developed by combining SIMS with a vacuum compatible microfluidic electrochemical device. Using this novel capability we report themore » first in situ elucidation of the electro-oxidation mechanism of a biologically significant organic compound, ascorbic acid (AA), at the electrode-electrolyte interface. The short-lived radical intermediate was successfully captured, which had not been detected directly before. Moreover, we demonstrated the power of this new technique in real-time monitoring of the formation and dynamic evolution of electrical double layers at the electrode-electrolyte interface. This work suggests further promising applications of in situ liquid SIMS in studying more complex chemical and biological events at the electrode-electrolyte interface.« less

Electrochemical Deposition of Conformal and Functional Layers on High Aspect Ratio Silicon Micro/Nanowires.

PubMed

Ozel, Tuncay; Zhang, Benjamin A; Gao, Ruixuan; Day, Robert W; Lieber, Charles M; Nocera, Daniel G

2017-07-12

Development of new synthetic methods for the modification of nanostructures has accelerated materials design advances to furnish complex architectures. Structures based on one-dimensional (1D) silicon (Si) structures synthesized using top-down and bottom-up methods are especially prominent for diverse applications in chemistry, physics, and medicine. Yet further elaboration of these structures with distinct metal-based and polymeric materials, which could open up new opportunities, has been difficult. We present a general electrochemical method for the deposition of conformal layers of various materials onto high aspect ratio Si micro- and nanowire arrays. The electrochemical deposition of a library of coaxial layers comprising metals, metal oxides, and organic/inorganic semiconductors demonstrate the materials generality of the synthesis technique. Depositions may be performed on wire arrays with varying diameter (70 nm to 4 μm), pitch (5 μ to 15 μ), aspect ratio (4:1 to 75:1), shape (cylindrical, conical, hourglass), resistivity (0.001-0.01 to 1-10 ohm/cm 2 ), and substrate orientation. Anisotropic physical etching of wires with one or more coaxial shells yields 1D structures with exposed tips that can be further site-specifically modified by an electrochemical deposition approach. The electrochemical deposition methodology described herein features a wafer-scale synthesis platform for the preparation of multifunctional nanoscale devices based on a 1D Si substrate.

Biophysical and electrochemical properties of Self-assembled noncovalent SWNT/DNA hybrid and electroactive nanostructure

NASA Astrophysics Data System (ADS)

Mirzapoor, Aboulfazl; Ranjbar, Bijan

2017-09-01

DNA self-assembled hybrid nanostructures are widely used in recent research in nanobiotechnology. Combination of DNA with carbon based nanoparticles such as single-walled carbon nanotube (SWNT), multi-walled carbon nanotube (MWNT) and carbon quantum dot were applied in important biological applications. Many examples of biosensors, nanowires and nanoelectronic devices, nanomachine and drug delivery systems are fabricated by these hybrid nanostructures. In this study, a new hybrid nanostructure has been fabricated by noncovalent interactions between single or double stranded DNA and SWNT nanoparticles and biophysical properties of these structures were studied comparatively. Biophysical properties of hybrid nanostructures studied by circular dichroism, UV-vis and fluorescence spectroscopy techniques. Also, electrochemical properties studied by cyclic voltammetry, linear sweep voltammetry, square wave voltammetry, choronoamperometry and impedance spectroscopy (EIS). Results revealed that the biophysical and electrochemical properties of SWNT/DNA hybrid nanostructures were different compare to ss-DNA, ds-DNA and SWNT singly. Circular dichroism results showed that ss-DNA wrapped around the nanotubes through π-π stacking interactions. The results indicated that after adding SWNT to ss-DNA and ds-DNA intensity of CD and UV-vis spectrum peaks were decreased. Electrochemical experiments indicated that the modification of single-walled carbon nanotubes by ss-DNA improves the electron transfer rate of hybrid nanostructures. It was demonstrated SWNT/DNA hybrid nanostructures should be a good electroactive nanostructure that can be used for electrochemical detection or sensing.

Macro-mechanics controls quantum mechanics: mechanically controllable quantum conductance switching of an electrochemically fabricated atomic-scale point contact

NASA Astrophysics Data System (ADS)

Staiger, Torben; Wertz, Florian; Xie, Fangqing; Heinze, Marcel; Schmieder, Philipp; Lutzweiler, Christian; Schimmel, Thomas

2018-01-01

Here, we present a silver atomic-scale device fabricated and operated by a combined technique of electrochemical control (EC) and mechanically controllable break junction (MCBJ). With this EC-MCBJ technique, we can perform mechanically controllable bistable quantum conductance switching of a silver quantum point contact (QPC) in an electrochemical environment at room temperature. Furthermore, the silver QPC of the device can be controlled both mechanically and electrochemically, and the operating mode can be changed from ‘electrochemical’ to ‘mechanical’, which expands the operating mode for controlling QPCs. These experimental results offer the perspective that a silver QPC may be used as a contact for a nanoelectromechanical relay.

Investigation of storage system designs and techniques for optimizing energy conservation in integrated utility systems. Volume 3: (Assessment of technical and cost characteristics of candidate IUS energy storage devices)

NASA Technical Reports Server (NTRS)

1976-01-01

Six energy storage technologies (inertial, superconducting magnetic, electrochemical, chemical, compressed air, and thermal) were assessed and evaluated for specific applicability to the IUS. To provide a perspective for the individual storage technologies, a brief outline of the general nature of energy storage and its significance to the user is presented.

Assessment of electrochemical properties of a biogalvanic system for tissue characterisation

PubMed Central

Chandler, J.H.; Culmer, P.R.; Jayne, D.G.; Neville, A.

2015-01-01

Biogalvanic characterisation is a promising method for obtaining health-specific tissue information. However, there is a dearth of understanding in the literature regarding the underlying galvanic cell, electrode reactions and their controlling factors which limits the application of the technique. This work presents a parametric electrochemical investigation into a zinc–copper galvanic system using salt (NaCl) solution analogues at physiologically-relevant concentrations (1.71, 17.1 & 154 mM). The potential difference at open cell, closed cell maximum current and the internal resistance (based on published characterisation methods) were measured. Additionally, independent and relative polarisation scans of the electrodes were performed to improve understanding of the system. Our findings suggest that the prominent reaction at the cathode is that of oxygen-reduction, not hydrogen-evolution. Results indicate that cell potentials are influenced by the concentration of dissolved oxygen at low currents and maximum closed cell currents are limited by the rate of oxygen diffusion to the cathode. Characterised internal resistance values for the salt solutions did not correspond to theoretical values at the extremes of concentration (1.71 and 154 mM) due to electrode resistance and current limitation. Existing biogalvanic models do not consider these phenomena and should be improved to advance the technique and its practical application. PMID:25460609

Pencil Graphite Electrodes: A Versatile Tool in Electroanalysis

PubMed Central

2017-01-01

Due to their electrochemical and economical characteristics, pencil graphite electrodes (PGEs) gained in recent years a large applicability to the analysis of various types of inorganic and organic compounds from very different matrices. The electrode material of this type of working electrodes is constituted by the well-known and easy commercially available graphite pencil leads. Thus, PGEs are cheap and user-friendly and can be employed as disposable electrodes avoiding the time-consuming step of solid electrodes surface cleaning between measurements. When compared to other working electrodes PGEs present lower background currents, higher sensitivity, good reproducibility, and an adjustable electroactive surface area, permitting the analysis of low concentrations and small sample volumes without any deposition/preconcentration step. Therefore, this paper presents a detailed overview of the PGEs characteristics, designs and applications of bare, and electrochemically pretreated and chemically modified PGEs along with the corresponding performance characteristics like linear range and detection limit. Techniques used for bare or modified PGEs surface characterization are also reviewed. PMID:28255500

Development of adaptive control applied to chaotic systems

NASA Astrophysics Data System (ADS)

Rhode, Martin Andreas

1997-12-01

Continuous-time derivative control and adaptive map-based recursive feedback control techniques are used to control chaos in a variety of systems and in situations that are of practical interest. The theoretical part of the research includes the review of fundamental concept of control theory in the context of its applications to deterministic chaotic systems, the development of a new adaptive algorithm to identify the linear system properties necessary for control, and the extension of the recursive proportional feedback control technique, RPF, to high dimensional systems. Chaos control was applied to models of a thermal pulsed combustor, electro-chemical dissolution and the hyperchaotic Rossler system. Important implications for combustion engineering were suggested by successful control of the model of the thermal pulsed combustor. The system was automatically tracked while maintaining control into regions of parameter and state space where no stable attractors exist. In a simulation of the electrochemical dissolution system, application of derivative control to stabilize a steady state, and adaptive RPF to stabilize a period one orbit, was demonstrated. The high dimensional adaptive control algorithm was applied in a simulation using the Rossler hyperchaotic system, where a period-two orbit with two unstable directions was stabilized and tracked over a wide range of a system parameter. In the experimental part, the electrochemical system was studied in parameter space, by scanning the applied potential and the frequency of the rotating copper disk. The automated control algorithm is demonstrated to be effective when applied to stabilize a period-one orbit in the experiment. We show the necessity of small random perturbations applied to the system in order to both learn the dynamics and control the system at the same time. The simultaneous learning and control capability is shown to be an important part of the active feedback control.

Electrochemical sensors and biosensors for the analysis of antineoplastic drugs.

PubMed

Lima, Handerson Rodrigues Silva; da Silva, Josany Saibrosa; de Oliveira Farias, Emanuel Airton; Teixeira, Paulo Ronaldo Sousa; Eiras, Carla; Nunes, Lívio César Cunha

2018-06-15

Cancer is a leading cause of death worldwide, often being treated with antineoplastic drugs that have high potential for toxicity to humans and the environment, even at very low concentrations. Therefore, monitoring these drugs is of utmost importance. Among the techniques used to detect substances at low concentrations, electrochemical sensors and biosensors have been noted for their practicality and low cost. This review brings, for the first time, a simplified outline of the main electrochemical sensors and biosensors developed for the analysis of antineoplastic drugs. The drugs analyzed and the methodology used for electrochemical sensing are described, as are the techniques used for drug quantification and the analytical performance of each sensor, highlighting the limit of detection (LOD), as well as the linear range of quantification (LR) for each system. Finally, we present a technological prospection on the development and use of electrochemical sensors and biosensors in the quantification of antineoplastic drugs. A search of international patent databases revealed no patents currently submitted under this topic, suggesting this is an area to be further explored. We also show that the use of these systems has been gaining prominence in recent years, and that the quantification of antineoplastic drugs using electrochemical techniques could bring great financial and health benefits. Copyright © 2018. Published by Elsevier B.V.

Direct Synthesis of Lithium-Intercalated Graphene for Electrochemical Energy Storage Application

DTIC Science & Technology

2011-01-01

for Electrochemical Energy Storage Application Ashavani Kumar,† Arava Leela Mohana Reddy,†,* Arnab Mukherjee,‡ Madan Dubey,§ Xiaobo Zhan,† Neelam...L.; Loper, A. L.; Rao , A. M.; Eklund, P. C. Electrochemical Oxidation of Single Wall Carbon Nanotube Bundles in Sulfuric Acid. J. Phys. Chem. B 1999

REVIEW ARTICLE: Environmental applications of analytical biosensors

NASA Astrophysics Data System (ADS)

Marco, María-Pilar; Barceló, Damià

1996-11-01

A review of the fundamental aspects and environmental applications of biosensors is presented. The bases of different transducer principles such as electrochemical, optical and piezoelectric are discussed. Various examples are given of the applications of such principles to develop immunosensor devices to determine common environmental contaminants. Attention is also paid to catalytic biosensors, using enzymes as sensing elements. Biosensor devices based on the use of cholinesterase and various oxidase enzymes such as tyrosinase, laccase, peroxidase and aldehyde dehydrogenase are reported. Some examples are given of the applications of other biomolecules such as whole cells, DNA or proteins, to determine pollution. Validation studies are presented comparing biosensors with chromatographic techniques to determine organophosphorus pesticides and phenolic compounds in environmental samples.

A dye-sensitized solar cell acting as the electrical reading box of an immunosensor: Application to CEA determination.

PubMed

Truta, Liliana A A N A; Moreira, Felismina T C; Sales, M Goreti F

2018-06-01

Monitoring cancer biomarkers in biological fluids has become a key tool for disease diagnosis, which should be of easy access anywhere in the world. The possibility of reducing basic requirements in the field of electrochemical biosensing may open doors in this direction. This work proposes for this purpose an innovative electrochemical immunosensing system using a photovoltaic cell as an electrical reading box. Immunosensing ensures accuracy, the electrochemical-ground of the device ensures sensitivity and detectability, and the photovoltaic cell drives the system towards electrical autonomy. As proof-of-concept, Carcinoembryonic antigen (CEA) was used herein, a cancer biomarker of clinical relevance. In brief, a conductive glass with a fluorine doped tin oxide film was used as conductive support and modified with anti-CEA by means of a bottom-up approach. All stages involved in the biochemical modification of the FTO surface were followed by electrochemical techniques, namely electrochemical impedance spectroscopy and cyclic voltammetry. This electrode acted as counter electrode of a dye-sensitized solar cells, and the electrical output of this cell was monitored for the different concentrations of CEA. Under optimized conditions, the device displayed a linear behaviour against CEA concentration, from 5 pg/mL to 15 ng/mL. The immunosensor was applied to the analysis of CEA in urine from healthy individual and spiked with the antigen. Overall, the presented approach demonstrates that photovoltaic cells may be employed as an electrical reading box of electrochemical biosensors, yielding a new direction towards autonomous electrochemical biosensing. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

In situ solid-state electrochemistry of mass-selected ions at well-defined electrode–electrolyte interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhakaran, Venkateshkumar; Johnson, Grant E.; Wang, Bingbing

2016-11-07

Molecular-level understanding of electrochemical processes occurring at electrode-electrolyte interfaces (EEI) is key to the rational development of high-performance and sustainable electrochemical technologies. This article reports the development and first application of solid-state in situ electrochemical probes to study redox and catalytic processes occurring at well-defined EEI generated using soft-landing of mass- and charge-selected cluster ions (SL). In situ electrochemical probes with excellent mass transfer properties are fabricated using carefully-designed nanoporous ionic liquid membranes. SL enables deposition of pure active species that are not obtainable with other techniques onto electrode surfaces with precise control over charge state, composition, and kinetic energy.more » SL is, therefore, a unique tool for studying fundamental processes occurring at EEI. For the first time using an aprotic electrochemical probe, the effect of charge state (PMo12O403-/2-) and the contribution of building blocks of Keggin polyoxometalate (POM) clusters to redox processes are characterized by populating EEI with novel POM anions generated by electrospray ionization and gas phase dissociation. Additionally, a proton conducting electrochemical probe has been developed to characterize the reactive electrochemistry (oxygen reduction activity) of bare Pt clusters (Pt40 ~1 nm diameter), thus demonstrating the capability of the probe for studying reactions in controlled gaseous environments. The newly developed in situ electrochemical probes combined with ion SL provide a versatile method to characterize the EEI in solid-state redox systems and reactive electrochemistry at precisely-defined conditions. This capability will advance molecular-level understanding of processes occurring at EEI that are critical to many energy-related technologies.« less

Ultramicroelectrode Array Based Sensors: A Promising Analytical Tool for Environmental Monitoring

PubMed Central

Orozco, Jahir; Fernández-Sánchez, César; Jiménez-Jorquera, Cecilia

2010-01-01

The particular analytical performance of ultramicroelectrode arrays (UMEAs) has attracted a high interest by the research community and has led to the development of a variety of electroanalytical applications. UMEA-based approaches have demonstrated to be powerful, simple, rapid and cost-effective analytical tools for environmental analysis compared to available conventional electrodes and standardised analytical techniques. An overview of the fabrication processes of UMEAs, their characterization and applications carried out by the Spanish scientific community is presented. A brief explanation of theoretical aspects that highlight their electrochemical behavior is also given. Finally, the applications of this transducer platform in the environmental field are discussed. PMID:22315551

Surface morphology and electrochemical studies on polyaniline/CuO nano composites

NASA Astrophysics Data System (ADS)

Ashokkumar, S. P.; Vijeth, H.; Yesappa, L.; Niranjana, M.; Vandana, M.; Basappa, M.; Devendrappa, H.

2018-05-01

An electrochemically synthesized Polyaniline (PANI) and Polyaniline/copper oxide (PCN) nano composite have studied the morphology and electrochemical properties. The composite is characterized by X-ray diffraction (XRD) and surface morphology was studied using FESEM and electrochemical behavior is studied using cyclic voltammetry (CV) technique. The CV curves shows rectangular shaped curve and they have contribution to electrical double layer capacitance (EDCL).

Method of preparing porous, rigid ceramic separators for an electrochemical cell. [Patent application

DOEpatents

Bandyopadhyay, G.; Dusek, J.T.

Porous, rigid separators for electrochemical cells are prepared by first calcining particles of ceramic material at temperatures above about 1200/sup 0/C for a sufficient period of time to reduce the sinterability of the particles. A ceramic powder that has not been calcined is blended with the original powder to control the porosity of the completed separator. The ceramic blend is then pressed into a sheet of the desired shape and sintered at a temperature somewhat lower than the calcination temperature. Separator sheets of about 1 to 2.5 mm thickness and 30 to 70% porosity can be prepared by this technique. Ceramics such as yttria, magnesium oxide, and magnesium-aluminium oxide have advantageously been used to form separators by this method.

Corrosion Studies of Wrought and Cast NASA-23 Alloy

NASA Technical Reports Server (NTRS)

Danford, M. D.

1997-01-01

Corrosion studies were carried out for wrought and cast NASA-23 alloy using electrochemical methods. The scanning reference electrode technique (SRET), the polarization resistance technique (PR), and the electrochemical impedance spectroscopy (EIS) were employed. These studies corroborate the findings of stress corrosion studies performed earlier, in that the material is highly resistant to corrosion.

Design, fabrication, and evaluation of on-chip micro-supercapacitors

NASA Astrophysics Data System (ADS)

Beidaghi, Majid

Due to the increasing demand for high power and reliable miniaturized energy storage devices, the development of micro-supercapacitors or electrochemical micro-capacitors have attracted much attention in recent years. This dissertation investigates several strategies to develop on-chip micro-supercapacitors with high power and energy density. Micro-supercapacitors based on interdigitated carbon micro-electrode arrays are fabricated through carbon microelectromechanical systems (C-MEMS) technique which is based on carbonization of patterned photoresist. To improve the capacitive behavior, electrochemical activation is performed on carbon micro-electrode arrays. The developed micro-supercapacitors show specific capacitances as high as 75 mFcm-2 at a scan rate of 5 mVs -1 after electrochemical activation for 30 minutes. The capacitance loss is less than 13% after 1000 cyclic voltammetry (CV) cycles. These results indicate that electrochemically activated C-MEMS micro-electrode arrays are promising candidates for on-chip electrochemical micro-capacitor applications. The energy density of micro-supercapacitors was further improved by conformal coating of polypyrrole (PPy) on C-MEMS structures. In these types of micro-devices the three dimensional (3D) carbon microstructures serve as current collectors for high energy density PPy electrodes. The electrochemical characterizations of these micro-supercapacitors show that they can deliver a specific capacitance of about 162.07 mFcm-2 and a specific power of 1.62mWcm -2 at a 20 mVs-1 scan rate. Addressing the need for high power micro-supercapacitors, the application of graphene as electrode materials for micro-supercapacitor was also investigated. The present study suggests a novel method to fabricate graphene-based micro-supercapacitors with thin film or in-plane interdigital electrodes. The fabricated micro-supercapacitors show exceptional frequency response and power handling performance and could effectively charge and discharge at rates as high as 50 Vs-1. CV measurements show that the specific capacitance of the micro-supercapacitor based on reduced graphene oxide and carbon nanotube composites is 6.1 mFcm -2 at scan rate of 0.01Vs-1. At a very high scan rate of 50 Vs-1, a specific capacitance of 2.8 mFcm-2 (stack capacitance of 3.1 Fcm-3) is recorded. This unprecedented performance can potentially broaden the future applications of micro-supercapacitors.

In-situ fabrication of zirconium-titanium nano-composite and its coating on Ti-6Al-4V for biomedical applications.

PubMed

Chellappa, Manickam; Vijayalakshmi, Uthirapathy

2017-02-01

In this study, nanocomposite powder consisting of zirconia and titania (Zr-Ti) have been synthesised by sol-gel method, with the aim of protecting Ti-6Al-4V surface. A simple and low cost electrophoretic deposition (EPD) technique has been employed for coating the nanocomposite material on Ti-6Al-4V. The prepared nanocomposite powder was characterised for its functional groups, phase purity, surface topography by Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy. Further, the biocompatibility nature of the composite powder was studied by [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] colorimetric assay and fluorescence analysis with MG63 osteoblast cell lines. The electrochemical behaviour of composite coating was investigated by potentiodynamic polarization and electrochemical impedance method. The results obtained from the electrochemical techniques indicate more corrosion resistance behaviour with increase of R ct value with the corresponding decrease in R dl values. From the above findings, the composite coating acts as a barrier layer against corrosion by preventing the leaching of metal ions from a dense and defect free coating. A scratch test analyser was used to assess the integrity of the coating; the lower traction force value of composite coating with increase in load has confirmed the presence of thick adherent layer on the substrate.

Study of fibrinogen adsorption on hydroxyapatite and TiO2 surfaces by electrochemical piezoelectric quartz crystal impedance and FTIR-ATR spectroscopy.

PubMed

Yang, Qin; Zhang, Youyu; Liu, Meiling; Ye, Min; Zhang, YuQin; Yao, Shouzhuo

2007-07-30

The electrochemical piezoelectric quartz crystal impedance (EQCI), a combined technique of piezoelectric quartz crystal impedance (PQCI), electrochemical impedance (EI), and Fourier transform infrared spectroscopy-attenuated total internal reflectance spectroscopy (FTIR-ATR) were used to in situ study the adsorption process of fibrinogen onto the surface of biomaterials-TiO2 and hydroxyapatite (Ca5(PO4)3OH, HAP). The equivalent circuit parameters, the resonance frequencies and the half peak width of the conductance spectrum of the two biomaterial-modified piezoelectric quartz crystal (PQC) resonances as well as the FTIR-ATR spectra of fibrinogen during fibrinogen adsorption on TiO2 and HAP particles modified electrode surface were obtained. The adsorption kinetics and mechanism of fibrinogen were investigated and discussed as well. The results suggested that two consecutive steps occurred during the adsorption of fibrinogen onto TiO2 and hydroxyapatite (HAP) surface. The fibrinogen molecules were firstly adsorbed onto the surface, and then the rearrangement of adsorbed fibrinogen or multi-layered adsorption occurred. The FTIR-ATR spectroscopy investigations showed that the secondary structure of fibrinogen molecules was altered during the adsorption and the adsorption kinetics of fibrinogen related with the variety of biomaterials. These experimental results suggest a way for enriching biological analytical science and developing new applications of analytical techniques, such as PQCI, EI, and FTIR-ATR.

Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

NASA Astrophysics Data System (ADS)

Maruthupandy, Muthusamy; Anand, Muthusamy; Maduraiveeran, Govindhan; Sait Hameedha Beevi, Akbar; Jeeva Priya, Radhakrishnan

2015-12-01

The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

Electrochemical enzymatic fenitrothion sensor based on a tyrosinase/poly(2-hydroxybenzamide)-modified graphite electrode.

PubMed

Alves, Maria de Fátima; Corrêa, Ricardo Augusto Moreira de Souza; da Cruz, Filipe Soares; Franco, Diego Leoni; Ferreira, Lucas Franco

2018-07-15

This paper reports the electrosynthesis and characterisation of a polymeric film derived from 2-hydroxybenzamide over a graphite electrode and its application as an enzymatic biosensor for the determination and quantification of the pesticide fenitrothion. The material was analysed by scanning electron microscopy and its electrochemical properties characterised by cyclic voltammetry and electrochemical impedance spectroscopy. The enzyme tyrosinase was immobilised over the modified electrode by the drop and dry technique. Catechol was determined by direct reduction of biocatalytically formed o-quinone by employing the flow injection analysis technique. The analytical characteristics of the proposed sensor were optimised as follows: phosphate buffer 0.050 M at pH 6.5, flow rate 5.0 mL min -1 , sample injection volume 150 μL, catechol concentration 1.0 mM and maximum inhibition time by fenitrothion of 6 min. The biosensors showed a linear response to pesticide concentration from 0.018 to 3.60 μM. The limit of detection and limit of quantification were calculated as 4.70 nM and 15.9 nM (RSD < 2.7%), respectively. The intra- and inter-electrode RSDs were 3.35% (n = 15) and 8.70% (n = 7), respectively. In addition, water samples spiked with the pesticide showed an average recovery of 97.6% (±1.53). Copyright © 2018 Elsevier Inc. All rights reserved.

Coupled diffusion and mechanics in battery electrodes

NASA Astrophysics Data System (ADS)

Eshghinejad, Ahmadreza

We are living in a world with continuous production and consumption of energy. The energy production in the past decades has started to move away from petrochemical sources toward sustainable sources such as solar, wind and geothermal. Also, the energy consumption is further adapting to the sustainable sources. For instance, in recent years electric vehicles are growing fast that can consume sustainable electric energy stored in their batteries. In this direction, in order to further move toward sustainable energy, materials are becoming increasingly important for storing electric energy. Although, currently the technologies such as Li-ion batteries and solid-oxide fuel cells are commercially available for energy applications, improvements are crucial for the next generation of many other technologies producing or consuming sustainable energies. A critical aspect of the electrochemical activities involved in energy storage technologies such as Li-ion batteries and solid-oxide fuel cells is the diffusion of ions into the electrode materials. This process ultimately governs various functional properties of the batteries such as capacity and charging/discharging rates. The first goal of this dissertation is to develop mathematical tools to analyze the ionic diffusion and investigate its coupling with mechanics in electrodes. For this purpose, a thermodynamics-based modeling framework is developed and numerically solved using two numerical methods to analyze ionic diffusion in heterogeneous and structured electrodes. The next goal of this dissertation is to develop and analyze characterization techniques to probe the electrochemical processes at the nano-scale. To this end, the mathematical models are first employed to model a previously developed Atomic Force Microscopy based technique to probe local electrochemical activities called Electrochemical Strain Microscopy (ESM). This method probes the activities by inducing AC electric field to perturb ionic activities and measuring the surface vibrations. Different aspects of this technique are analyzed and the limitations are discussed. Such limitations moves the dissertation toward development of a new technique for probing the electrochemical activities, to overcome the previous limitations, called Scanning Thermo-ionic Microscopy (STIM). In this method, the local activities are probed by inducing AC temperature oscillations to perturb ionic activities and measuring the surface vibrations. The principle mathematical analysis of the coupled governing equations and the method of probing electrochemical activities are discussed in detail. Also, the method is implemented into the AFM hardware/software and the STIM response is confirmed using experiments on LiFePO4 and Sm-doped Ceria as well-known battery and fuel cell electrodes. The STIM method provides a clean method for analyzing energy storage materials and designing novel nano-structured materials for improved performance. Finally, conclusion of the presented work is discussed in the last chapter and the future works to continue the development of the modeling and experiments are listed.

Electrochemical studies of Copper, Tantalum and Tantalum Nitride surfaces in aqueous solutions for applications in chemical-mechanical and electrochemical-mechanical planarization

NASA Astrophysics Data System (ADS)

Sulyma, Christopher Michael

This report will investigate fundamental properties of materials involved in integrated circuit (IC) manufacturing. Individual materials (one at a time) are studied in different electrochemical environmental solutions to better understand the kinetics associated with the polishing process. Each system tries to simulate a real CMP environment in order to compare our findings with what is currently used in industry. To accomplish this, a variety of techniques are used. The voltage pulse modulation technique is useful for electrochemical processing of metal and alloy surfaces by utilizing faradaic reactions like electrodeposition and electrodissolution. A theoretical framework is presented in chapter 4 to facilitate quantitative analysis of experimental data (current transients) obtained in this approach. A typical application of this analysis is demonstrated for an experimental system involving electrochemical removal of copper surface layers, a relatively new process for abrasive-free electrochemical mechanical planarization of copper lines used in the fabrication of integrated circuits. Voltage pulse modulated electrodissolution of Cu in the absence of mechanical polishing is activated in an acidic solution of oxalic acid and hydrogen peroxide. The current generated by each applied voltage step shows a sharp spike, followed by a double-exponential decay, and eventually attains the rectangular shape of the potential pulses. For the second system in chapter 5, open-circuit potential measurements, cyclic voltammetry and Fourier transform impedance spectroscopy have been used to study pH dependent surface reactions of Cu and Ta rotating disc electrodes (RDEs) in aqueous solutions of succinic acid (SA, a complexing agent), hydrogen peroxide (an oxidizer), and ammonium dodecyl sulfate (ADS, a corrosion inhibitor for Cu). The surface chemistries of these systems are relevant for the development of a single-slurry approach to chemical mechanical planarization (CMP) of Cu lines and Ta barriers in the fabrication of semiconductor devices. It is shown that in non-alkaline solutions of H2O2, the SA-promoted surface complexes of Cu and Ta can potentially support chemically enhanced material removal in low-pressure CMP of surface topographies overlying fragile low-k dielectrics. ADS can suppress Cu dissolution without significantly affecting the surface chemistry of Ta. Chapter 6 discusses anodic corrosion of Ta, which is examined as a possible route to voltage induced removal of Ta for potential applications in electrochemical mechanical planarization (ECMP) of diffusion barriers. This strategy involves electro-oxidation of Ta in the presence of NO3- anions to form mechanically weak surface oxide films, followed by removal of the oxide layers by moderate mechanical abrasion. This NO3 - system is compared with a reference solution of Br -. In both electrolytes, the voltammetric currents of anodic oxidation exhibit oscillatory behaviors in the initial cycles of slow (5 mV s-1) voltage scans. The frequencies of these current oscillations are show signature attributes of localized pitting or general surface corrosion caused by Br- or NO3 -, respectively. Scanning electron microscopy, cyclic voltammetry, polarization resistance measurements, and time resolved Fourier transform impedance spectroscopy provide additional details about these corrosion mechanism. Apart from their relevance in the context of ECMP, the results also address certain fundamental aspects of pitting and general corrosions. The general protocols necessary to combine and analyze the results of D.C. and A.C. electrochemical measurements involving such valve metal corrosion systems are discussed in detail. In chapter 7 potassium salts of certain oxyanions (nitrate, sulfate and phosphate in particular) are shown to serve as effective surface-modifying agents in chemically enhanced, low-pressure chemical mechanical planarization (CMP) of Ta and TaN barrier layers for interconnect structures. The surface reactions that form the basis of this CMP strategy are investigated here in detail using the electrochemical techniques of cyclic voltammetry, open circuit potential analysis, polarization resistance measurements, and Fourier transform impedance spectroscopy. The results suggest that forming structurally weak oxide layers on the CMP samples is a key to achieving the goal of chemically controlled CMP of Ta/TaN at low down-pressures. (Abstract shortened by UMI.)

Elucidation of the Biological Redox Chemistry of Purines Using Electrochemical Techniques.

ERIC Educational Resources Information Center

Dryhurst, Glenn; And Others

1983-01-01

Electrochemical studies can give insights into the chemical aspects of enzymatic and in vivo redox reactions of naturally occurring organic compounds. This is illustrated by studies of the electrochemical oxidation of the purinem uric acid. The discussion is limited to information at pH 7 or greater. (JN)

Structures and fabrication techniques for solid state electrochemical devices

DOEpatents

Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

2006-10-10

Low-cost, mechanically strong, highly electronically conductive porous substrates and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures provide solid state electrochemical device substrates of novel composition and techniques for forming thin electrode/membrane/electrolyte coatings on the novel or more conventional substrates. In particular, in one aspect the invention provides techniques for co-firing of device substrate (often an electrode) with an electrolyte or membrane layer to form densified electrolyte/membrane films 5 to 20 microns thick. In another aspect, densified electrolyte/membrane films 5 to 20 microns thick may be formed on a pre-sintered substrate by a constrained sintering process. In some cases, the substrate may be a porous metal, alloy, or non-nickel cermet incorporating one or more of the transition metals Cr, Fe and Cu, or alloys thereof.

Stereoisomers Separation

NASA Astrophysics Data System (ADS)

Wieczorek, Piotr

The use of capillary electrophoresis for enantiomer separation and optical purity determination is presented. The contents start with basic information about the nature of stereoizomers and the mechanism of enantioseparation using capillary electrophoresis techniques. The molecules to be separated show identical chemical structure and electrochemical behavior. Therefore, the chiral recognition of enantiomers is possible only by bonding to chiral selector and the separation based on very small differences in complexation energies of diastereomer complexes formed. This method is useful for this purpose due to the fact that different compounds can be used as chiral selectors. The mostly used chiral selectors like cyclodextrins, crown ethers, chiral surfactants, macrocyclic antibiotics, transition metal complexes, natural, and synthetic polymers and their application for this purpose is also discussed. Finally, examples of practical applications of electromigration techniques for enantiomers separation and determination are presented.

Chemically deposited nano grain composed MoS(2) thin films for supercapacitor application.

PubMed

Pujari, R B; Lokhande, A C; Shelke, A R; Kim, J H; Lokhande, C D

2017-06-15

Low temperature soft chemical synthesis approach is employed towards MoS 2 thin film preparation on cost effective stainless steel substrate. 3-D semispherical nano-grain composed surface texture of MoS 2 film is observed through FE-SEM technique. Electrochemical supercapacitor performance of MoS 2 film is tested from cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) techniques in 1M aqueous Na 2 SO 4 electrolyte. Specific capacitance (C s ) of 180Fg -1 with CV cycling stability of 82% for 1000 cycles is achieved. Equivalent series resistance (R s ) of 1.78Ωcm -2 observed through Nyquist plot shows usefulness of MoS 2 thin film for charge conduction in supercapacitor application. Copyright © 2016. Published by Elsevier Inc.

Space Electrochemical Research and Technology

NASA Technical Reports Server (NTRS)

1991-01-01

The proceedings of NASA's third Space Electrochemical Research and Technology (SERT) conference are presented. The objective of the conference was to assess the present status and general thrust of research and development in those areas of electrochemical technology required to enable NASA missions in the next century. The conference provided a forum for the exchange of ideas and opinions of those actively involved in the field, in order to define new opportunities for the application of electrochemical processes in future NASA missions. Papers were presented in three technical areas: the electrochemical interface, the next generation in aerospace batteries and fuel cells, and electrochemistry for nonenergy storage applications.

Examination of Chemical Adsorption and Marine Biofouling on Metal Surfaces Using Raman Scattering Techniques and Electrochemical Impedance Spectroscopy

DTIC Science & Technology

1991-03-14

analyses of labeled model compounds, such as the protein, RuBisCO (Ribulose Bisphosphate CarboxylaselOxygenase). (3) Examine adsorption of...coverages were determined radiometrically using tritiated RuBisCO . Although natural thin films were detectable using Raman scattering techniques...optical, electrochemical, and radiometric techniques and the protein RuBisCO as a model adsorbate on titanium, copper, and iron, we have been able to

Low-dimensional carbon and MXene-based electrochemical capacitor electrodes.

PubMed

Yoon, Yeoheung; Lee, Keunsik; Lee, Hyoyoung

2016-04-29

Due to their unique structure and outstanding intrinsic physical properties such as extraordinarily high electrical conductivity, large surface area, and various chemical functionalities, low-dimension-based materials exhibit great potential for application in electrochemical capacitors (ECs). The electrical properties of electrochemical capacitors are determined by the electrode materials. Because energy charge storage is a surface process, the surface properties of the electrode materials greatly influence the electrochemical performance of the cell. Recently, graphene, a single layer of sp(2)-bonded carbon atoms arrayed into two-dimensional carbon nanomaterial, has attracted wide interest as an electrode material for electrochemical capacitor applications due to its unique properties, including a high electrical conductivity and large surface area. Several low-dimensional materials with large surface areas and high conductivity such as onion-like carbons (OLCs), carbide-derived carbons (CDCs), carbon nanotubes (CNTs), graphene, metal hydroxide, transition metal dichalcogenides (TMDs), and most recently MXene, have been developed for electrochemical capacitors. Therefore, it is useful to understand the current issues of low-dimensional materials and their device applications.

Insights into electrochemical reactions from ambient pressure photoelectron spectroscopy.

PubMed

Stoerzinger, Kelsey A; Hong, Wesley T; Crumlin, Ethan J; Bluhm, Hendrik; Shao-Horn, Yang

2015-11-17

The understanding of fundamental processes in the bulk and at the interfaces of electrochemical devices is a prerequisite for the development of new technologies with higher efficiency and improved performance. One energy storage scheme of great interest is splitting water to form hydrogen and oxygen gas and converting back to electrical energy by their subsequent recombination with only water as a byproduct. However, kinetic limitations to the rate of oxygen-based electrochemical reactions hamper the efficiency in technologies such as solar fuels, fuel cells, and electrolyzers. For these reactions, the use of metal oxides as electrocatalysts is prevalent due to their stability, low cost, and ability to store oxygen within the lattice. However, due to the inherently convoluted nature of electrochemical and chemical processes in electrochemical systems, it is difficult to isolate and study individual electrochemical processes in a complex system. Therefore, in situ characterization tools are required for observing related physical and chemical processes directly at the places where and while they occur and can help elucidate the mechanisms of charge separation and charge transfer at electrochemical interfaces. X-ray photoelectron spectroscopy (XPS), also known as ESCA (electron spectroscopy for chemical analysis), has been used as a quantitative spectroscopic technique that measures the elemental composition, as well as chemical and electronic state of a material. Building from extensive ex situ characterization of electrochemical systems, initial in situ studies were conducted at or near ultrahigh vacuum (UHV) conditions (≤10(-6) Torr) to probe solid-state electrochemical systems. However, through the integration of differential-pumping stages, XPS can now operate at pressures in the torr range, comprising a technique called ambient pressure XPS (AP-XPS). In this Account, we briefly review the working principles and current status of AP-XPS. We use several recent in situ studies on model electrochemical components as well as operando studies performed by our groups at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory to illustrate that AP-XPS is both a chemically and an electrically specific tool since photoelectrons carry information on both the local chemistry and electrical potentials. The applications of AP-XPS to oxygen electrocatalysis shown in this Account span well-defined studies of (1) the oxide/oxygen gas interface, (2) the oxide/water vapor interface, and (3) operando measurements of half and full electrochemical cells. Using specially designed model devices, we can expose and isolate the electrode or interface of interest to the incident X-ray beam and AP-XPS analyzer to relate the electrical potentials to the composition/chemical state of the key components and interfaces. We conclude with an outlook on new developments of AP-XPS end stations, which may provide significant improvement in the observation of dynamics over a wide range of time scales, higher spatial resolution, and improved characterization of boundary or interface layers (solid/solid and liquid/solid).

Fabrication strategies, sensing modes and analytical applications of ratiometric electrochemical biosensors.

PubMed

Jin, Hui; Gui, Rijun; Yu, Jianbo; Lv, Wei; Wang, Zonghua

2017-05-15

Previously developed electrochemical biosensors with single-electric signal output are probably affected by intrinsic and extrinsic factors. In contrast, the ratiometric electrochemical biosensors (RECBSs) with dual-electric signal outputs have an intrinsic built-in correction to the effects from system or background electric signals, and therefore exhibit a significant potential to improve the accuracy and sensitivity in electrochemical sensing applications. In this review, we systematically summarize the fabrication strategies, sensing modes and analytical applications of RECBSs. First, the different fabrication strategies of RECBSs were introduced, referring to the analytes-induced single- and dual-dependent electrochemical signal strategies for RECBSs. Second, the different sensing modes of RECBSs were illustrated, such as differential pulse voltammetry, square wave voltammetry, cyclic voltammetry, alternating current voltammetry, electrochemiluminescence, and so forth. Third, the analytical applications of RECBSs were discussed based on the types of target analytes. Finally, the forthcoming development and future prospects in the research field of RECBSs were also highlighted. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrodeposited manganese dioxide nanostructures on electro-etched carbon fibers: High performance materials for supercapacitor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazemi, Sayed Habib, E-mail: habibkazemi@iasbs.ac.ir; Center for Research in Climate Change and Global Warming; Maghami, Mostafa Ghaem

Highlights: • We report a facile method for fabrication of MnO{sub 2} nanostructures on electro-etched carbon fiber. • MnO{sub 2}-ECF electrode shows outstanding supercapacitive behavior even at high discharge rates. • Exceptional cycle stability was achieved for MnO{sub 2}-ECF electrode. • The coulombic efficiency of MnO{sub 2}-ECF electrode is nearly 100%. - Abstract: In this article we introduce a facile, low cost and additive/template free method to fabricate high-rate electrochemical capacitors. Manganese oxide nanostructures were electrodeposited on electro-etched carbon fiber substrate by applying a constant anodic current. Nanostructured MnO{sub 2} on electro-etched carbon fiber was characterized by scanning electron microscopy,more » X-ray diffraction and energy dispersive X-ray analysis. The electrochemical behavior of MnO{sub 2} electro-etched carbon fiber electrode was investigated by electrochemical techniques including cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. A maximum specific capacitance of 728.5 F g{sup −1} was achieved at a scan rate of 5 mV s{sup −1} for MnO{sub 2} electro-etched carbon fiber electrode. Also, this electrode showed exceptional cycle stability, suggesting that it can be considered as a good candidate for supercapacitor electrodes.« less

Electrochemical detection of Nanog in cell extracts via target-induced resolution of an electrode-bound DNA pseudoknot.

PubMed

Ma, Jiehua; Li, Chao; Tao, Yaqin; Feng, Chang; Li, Genxi

2016-12-15

Nanog is among the most important indicators of cell pluripotency and self-renew, so detection of Nanog is critical for tumor assessment and monitoring of clinical prognosis. In this work, a novel method for Nanog detection is proposed by using electrochemical technique based on target-induced conformational change of an electrode-bound DNA pseudoknot. In the absence of Nanog, the rigid structure of the pseudoknot will minimize the connection between the redox tag and the electrode, thus reducing the obtained faradaic current. Nevertheless, the Nanog binding may liberate the flexible single-stranded element that transforms the DNA pesudokont into DNA hairpin structure due to steric hindrance effect, thus making the electrochemical tag close to the electrode surface. Consequently, electron transfer can be enhanced and very well electrochemical response can be observed. By using the proposed method, Nanog can be determined in a linear range from 2nM to 25nM with a detection limit of 163 pM. Furthermore, the proposed method can be directly used to assay Nanog not only in purified samples but also in complex media (cell extracts), which shows potential applications in Nanog functional studies as well as clinical diagnosis in the future. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrochemistry of metal chloride cathodes in sodium batteries

NASA Technical Reports Server (NTRS)

Ratnakumar, B. V.; Di Stefano, S.; Halpert, G.

1990-01-01

Fundamental electrochemical studies on three candidate materials, i.e., FeCl2, NiCl2, and CuCl2, were carried out using various techniques, such as cyclic voltammetry, linear polarization, potentiodynamic polarization, and ac impedance. These studies were aimed at identifying various rate processes in the reduction, elucidating the reaction mechanisms, and determining the kinetic parameters for the reduction. The limitations in the performance of these cathode materials in high power density applications were also examined. Finally, recommendations were made from these studies for the selection of a candidate system among these materials for future NASA applications.

Mapping Ionic Currents and Reactivity on the Nanoscale: Electrochemical Strain Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalinin, S.V.

2010-10-19

Solid-state electrochemical processes in oxides underpin a broad spectrum of energy and information storage devices, ranging from Li-ion and Li-air batteries, to solid oxide fuel cells (SOFC) to electroresistive and memristive systems. These functionalities are controlled by the bias-driven diffusive and electromigration transport of mobile ionic species, as well as intricate a set of electrochemical and defect-controlled reactions at interfaces and in bulk. Despite the wealth of device-level and atomistic studies, little is known on the mesoscopic mechanisms of ion diffusion and electronic transport on the level of grain clusters, individual grains, and extended defects. The development of the capabilitymore » for probing ion transport on the nanometer scale is a key to deciphering complex interplay between structure, functionality, and performance in these systems. Here we introduce Electrochemical Strain Microscopy, a scanning probe microscopy technique based on strong strain-bias coupling in the systems in which local ion concentrations are changed by electrical fields. The imaging capability, as well as time- and voltage spectroscopies analogous to traditional current based electrochemical characterization methods are developed. The reversible intercalation of Li and mapping electrochemical activity in LiCoO2 is demonstrated, illustrating higher Li diffusivity at non-basal planes and grain boundaries. In Si-anode device structure, the direct mapping of Li diffusion at extended defects and evolution of Li-activity with charge state is explored. The electrical field-dependence of Li mobility is studied to determine the critical bias required for the onset of electrochemical transformation, allowing reaction and diffusion processes in the battery system to be separated at each location. Finally, the applicability of ESM for probing oxygen vacancy diffusion and oxygen reduction/evolution reactions is illustrated, and the high resolution ESM maps are correlated with aberration corrected scanning transmission electron microscopy imaging. The future potential for deciphering mechanisms of electrochemical transformations on an atomically-defined single-defect level is discussed.« less

MnO2 prepared by hydrothermal method and electrochemical performance as anode for lithium-ion battery.

PubMed

Feng, Lili; Xuan, Zhewen; Zhao, Hongbo; Bai, Yang; Guo, Junming; Su, Chang-Wei; Chen, Xiaokai

2014-01-01

Two α-MnO2 crystals with caddice-clew-like and urchin-like morphologies are prepared by the hydrothermal method, and their structure and electrochemical performance are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), galvanostatic cell cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The morphology of the MnO2 prepared under acidic condition is urchin-like, while the one prepared under neutral condition is caddice-clew-like. The identical crystalline phase of MnO2 crystals is essential to evaluate the relationship between electrochemical performances and morphologies for lithium-ion battery application. In this study, urchin-like α-MnO2 crystals with compact structure have better electrochemical performance due to the higher specific capacity and lower impedance. We find that the relationship between electrochemical performance and morphology is different when MnO2 material used as electrochemical supercapacitor or as anode of lithium-ion battery. For lithium-ion battery application, urchin-like MnO2 material has better electrochemical performance.

Microfluidic electrochemical reactors

DOEpatents

Nuzzo, Ralph G [Champaign, IL; Mitrovski, Svetlana M [Urbana, IL

2011-03-22

A microfluidic electrochemical reactor includes an electrode and one or more microfluidic channels on the electrode, where the microfluidic channels are covered with a membrane containing a gas permeable polymer. The distance between the electrode and the membrane is less than 500 micrometers. The microfluidic electrochemical reactor can provide for increased reaction rates in electrochemical reactions using a gaseous reactant, as compared to conventional electrochemical cells. Microfluidic electrochemical reactors can be incorporated into devices for applications such as fuel cells, electrochemical analysis, microfluidic actuation, pH gradient formation.

Electrochemical method for measuring corrosion of metals in wood

Treesearch

Samuel L. Zelinka; Douglas Rammer

2006-01-01

Preliminary studies have shown that electrochemical methods, especially Electrochemical Impedance Spectroscopy (EIS), appear to have great promise for measuring the corrosion rate of metals in wood. One of the major reasons for using these techniques is the ability to maintain moisture content and temperature at conditions encountered in service while measuring the...

Novel hand-held device for exhaled nitric oxide-analysis in research and clinical applications.

PubMed

Hemmingsson, Tryggve; Linnarsson, Dag; Gambert, Rudolf

2004-12-01

Changes in expired nitric oxide (NO) occur in airway inflammation and have proved to be important in the monitoring of inflammatory disease processes such as asthma. We set out to develop a novel hand-held NO-analyzer with a performance comparable to the present more costly and complex chemiluminescence instruments. The new device is based on a specially designed electrochemical sensor, where we have developed a novel sampling and analysis technology, compensating for the relatively slow response properties of the electrochemical sensor technique. A Lowest Detection Limit in NO-analysis from reference gas tests of less than 3 ppb and a response time of 15 seconds together with an average precision in human breath measurements of 1.4 ppb were obtained. We also show an agreement with the existing 'gold standard' FENO measurement technique, within 0.5 ppb in a group of 19 subjects together with a high linearity and accuracy compared to reference gases. The new analyzer enables affordable monitoring of inflammatory airway diseases in research and routine clinical practice.

An Electrochemical Impedance Spectroscopy System for Monitoring Pineapple Waste Saccharification.

PubMed

Conesa, Claudia; Ibáñez Civera, Javier; Seguí, Lucía; Fito, Pedro; Laguarda-Miró, Nicolás

2016-02-04

Electrochemical impedance spectroscopy (EIS) has been used for monitoring the enzymatic pineapple waste hydrolysis process. The system employed consists of a device called Advanced Voltammetry, Impedance Spectroscopy & Potentiometry Analyzer (AVISPA) equipped with a specific software application and a stainless steel double needle electrode. EIS measurements were conducted at different saccharification time intervals: 0, 0.75, 1.5, 6, 12 and 24 h. Partial least squares (PLS) were used to model the relationship between the EIS measurements and the sugar determination by HPAEC-PAD. On the other hand, artificial neural networks: (multilayer feed forward architecture with quick propagation training algorithm and logistic-type transfer functions) gave the best results as predictive models for glucose, fructose, sucrose and total sugars. Coefficients of determination (R²) and root mean square errors of prediction (RMSEP) were determined as R² > 0.944 and RMSEP < 1.782 for PLS and R² > 0.973 and RMSEP < 0.486 for artificial neural networks (ANNs), respectively. Therefore, a combination of both an EIS-based technique and ANN models is suggested as a promising alternative to the traditional laboratory techniques for monitoring the pineapple waste saccharification step.

One-pot electrochemical growth of sponge-like polyaniline-intercalated phosphorous-doped graphene oxide on nickel foam as binder-free electrode material of supercapacitor

NASA Astrophysics Data System (ADS)

Bigdeli, Hadise; Moradi, Morteza; Borhani, Saeid; Jafari, Elnaz Abbasi; Hajati, Shaaker; Kiani, Mohammad Ali

2018-06-01

In this work, phosphor-doped graphene oxide (PGO) was synthesized by chemical technique. Also, the sponge-like PGO@polyaniline nanocomposite (PGO@PANI) film was coated on the nickel foam by one-step electropolymerization. The active materials were then characterized by Fourier transforms infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller technique. When PANI/PGO was used as supercapacitor electrode, under current density of 1 A/g, the specific capacitance of the prepared PGO@PANI was measured as 603 F/g, which is 6.0 times higher than that of pure PANI (102 F/g). Moreover, capacity stability of the PANI/PGO increased significantly as compared to PANI (65% vs. 44%) after increasing the current density from 1 to 15 A/g. The clear electrochemical performance of PANI/PGO was enhanced owing to the synergistic effect of PGO and PANI. Our results demonstrate that PANI/PGO nanosheet arrays are promising candidate for electrode supercapacitor applications.

Fabrication of a symmetric micro supercapacitor based on tubular ruthenium oxide on silicon 3D microstructures

NASA Astrophysics Data System (ADS)

Wang, Xiaofeng; Yin, Yajiang; Li, Xiangyu; You, Zheng

2014-04-01

A micro-supercapacitor with a three-dimensional configuration has been fabricated using an ICP etching technique. Hydrous ruthenium oxide with a tubular morphology is successfully synthesized using a cathodic deposition technique with a Si micro prominence as a template. The desired tubular RuO2·xH2O architecture facilitates electrolyte penetration and proton exchange/diffusion. A single MEMS electrode is studied using cyclic voltammetry, and a specific capacitance of 99.3 mF cm-2 and 70 F g-1 is presented at 5 mV s-1 in neutral Na2SO4 solution. The accelerated cycle life is tested at 80 mV s-1, and satisfactory cyclability is observed. When placed on a chip, the symmetric cell exhibits good supercapacitor properties, and a specific capacitance as high as 23 mF cm-2 is achieved at 10 mA cm-2. Therefore, 3D MEMS microelectrode arrays with electrochemically deposited ruthenium oxide films are promising candidates for on-chip electrochemical micro-capacitor applications.

Electrochemical synthesis and photoelectrochemical properties of grass-like nanostructured α-Fe2O3 photoanodes for use in solar water oxidation

NASA Astrophysics Data System (ADS)

Hanedar, Yesim; Demir, Umit; Oznuluer, Tuba

2016-10-01

Grass-like nanostructured α-Fe2O3 photoelectrodes were prepared for the first time through a simple cathodic electrodeposition method from an oxygenated aqueous solution of Fe3+ at room temperature without using surfactant, capping agents or any other additives. The α-Fe2O3 electrodeposits were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis absorption and photoelectrochemical (PEC) techniques. The SEM and XRD results indicated that the as-deposited α-Fe2O3 are composed of single crystalline nanoleaves. The formation mechanisms of α-Fe2O3 have also been proposed based on a series of cyclic voltammetric and XPS studies. This new electrochemical method is expected to be a useful technique for the fabrication of single crystalline and photoactive α-Fe2O3 nanostructures directly onto the electrode surface, which is required in most applications, such as energy conversion and storage and sensors.

Electrochemically active biofilms: facts and fiction. A review

PubMed Central

Babauta, Jerome; Renslow, Ryan; Lewandowski, Zbigniew; Beyenal, Haluk

2014-01-01

This review examines the electrochemical techniques used to study extracellular electron transfer in the electrochemically active biofilms that are used in microbial fuel cells and other bioelectrochemical systems. Electrochemically active biofilms are defined as biofilms that exchange electrons with conductive surfaces: electrodes. Following the electrochemical conventions, and recognizing that electrodes can be considered reactants in these bioelectrochemical processes, biofilms that deliver electrons to the biofilm electrode are called anodic, ie electrode-reducing, biofilms, while biofilms that accept electrons from the biofilm electrode are called cathodic, ie electrode-oxidizing, biofilms. How to grow these electrochemically active biofilms in bioelec-trochemical systems is discussed and also the critical choices made in the experimental setup that affect the experimental results. The reactor configurations used in bioelectrochemical systems research are also described and the authors demonstrate how to use selected voltammetric techniques to study extracellular electron transfer in bioelectrochemical systems. Finally, some critical concerns with the proposed electron transfer mechanisms in bioelectrochemical systems are addressed together with the prospects of bioelectrochemical systems as energy-converting and energy-harvesting devices. PMID:22856464

Sputtered Pd as hydrogen storage for a chip-integrated microenergy system.

PubMed

Slavcheva, E; Ganske, G; Schnakenberg, U

2014-01-01

The work presents a research on preparation and physical and electrochemical characterisation of dc magnetron sputtered Pd films envisaged for application as hydrogen storage in a chip-integrated hydrogen microenergy system. The influence of the changes in the sputtering pressure on the surface structure, morphology, and roughness was analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AMF). The electrochemical activity towards hydrogen adsorption/desorption and formation of PdH were investigated in 0.5 M H2SO4 using the methods of cyclic voltammetry and galvanostatic polarisation. The changes in the electrical properties of the films as a function of the sputtering pressure and the level of hydrogenation were evaluated before and immediately after the electrochemical charging tests, using a four-probe technique. The research resulted in establishment of optimal sputter regime, ensuring fully reproducible Pd layers with highly developed surface, moderate porosity, and mechanical stability. Selected samples were integrated as hydrogen storage in a newly developed unitized microenergy system and tested in charging (water electrolysis) and discharging (fuel cell) operative mode at ambient conditions demonstrating a stable recycling performance.

A novel fabrication method of carbon electrodes using 3D printing and chemical modification process.

PubMed

Tian, Pan; Chen, Chaoyang; Hu, Jie; Qi, Jin; Wang, Qianghua; Chen, Jimmy Ching-Ming; Cavanaugh, John; Peng, Yinghong; Cheng, Mark Ming-Cheng

2017-11-23

Three-dimensional (3D) printing is an emerging technique in the field of biomedical engineering and electronics. This paper presents a novel biofabrication method of implantable carbon electrodes with several advantages including fast prototyping, patient-specific and miniaturization without expensive cleanroom. The method combines stereolithography in additive manufacturing and chemical modification processes to fabricate electrically conductive carbon electrodes. The stereolithography allows the structures to be 3D printed with very fine resolution and desired shapes. The resin is then chemically modified to carbon using pyrolysis to enhance electrochemical performance. The electrochemical characteristics of 3D printing carbon electrodes are assessed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The specific capacitance of 3D printing carbon electrodes is much higher than the same sized platinum (Pt) electrode. In-vivo electromyography (EMG) recording, 3D printing carbon electrodes exhibit much higher signal-to-noise ratio (40.63 ± 7.73) than Pt electrodes (14.26 ± 6.83). The proposed biofabrication method is envisioned to enable 3D printing in many emerging applications in biomedical engineering and electronics.

Application of 1-hydroxyethylidene-1, 1-diphosphonic acid in boiler water for industrial boilers.

PubMed

Zeng, Bin; Li, Mao-Dong; Zhu, Zhi-Ping; Zhao, Jun-Ming; Zhang, Hui

2013-01-01

The primary method used for boiler water treatment is the addition of chemicals to industrial boilers to prevent corrosion and scaling. The static scale inhibition method was used to evaluate the scale inhibition performance of 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP). Autoclave static experiments were used to study the corrosion inhibition properties of the main material for industrial boilers (20# carbon steel) with an HEDP additive in the industrial boiler water medium. The electrochemical behavior of HEDP on carbon steel corrosion control was investigated using electrochemical impedance spectroscopy and Tafel polarization techniques. Experimental results indicate that HEDP can have a good scale inhibition effect when added at a quantity of 5 to 7 mg/L at a test temperature of not more than 100 °C. To achieve a high scale inhibition rate, the HEDP dosage must be increased when the test temperature exceeds 100 °C. Electrochemical and autoclave static experimental results suggest that HEDP has a good corrosion inhibition effect on 20# carbon steel at a concentration of 25 mg/L. HEDP is an excellent water treatment agent.

Fixed Junction Light Emitting Electrochemical Cells based on Polymerizable Ionic Liquids

NASA Astrophysics Data System (ADS)

Brown, Erin; Limanek, Austin; Bauman, James; Leger, Janelle

Organic photovoltaic (OPV) devices are of interest due to ease of fabrication, which increases their cost-effectiveness. OPV devices based on fixed-junction light emitting electrochemical cells (LECs) in particular have shown promising results. LECs are composed of a layer of polymer semiconductor blended with a salt sandwiched between two electrodes. As a forward bias is applied, the ions within the polymer separate, migrate to the electrodes, and enable electrochemical doping, thereby creating a p-n junction analog. In a fixed junction device, the ions are immobilized after the desired distribution has been established, allowing for operation under reverse bias conditions. Fixed junctions can be established using various techniques, including chemically by mixing polymerizable salts that will bond to the polymer under a forward bias. Previously we have demonstrated the use of the polymerizable ionic liquid allyltrioctylammonium allysulfonate (ATOAAS) as an effective means of creating a chemically fixed junction in an LEC. Here we present the application of this approach to the creation of photovoltaic devices. Devices demonstrate higher open circuit voltages, faster charging, and an overall improved device performance over previous chemically-fixed junction PV devices.

One-step facile hydrothermal synthesis of Fe2O3@LiCoO2 composite as excellent supercapacitor electrode materials

NASA Astrophysics Data System (ADS)

Gopi, Chandu V. V. Muralee; Somasekha, A.; Reddy, Araveeti Eswar; Kim, Soo-Kyoung; Kim, Hee-Je

2018-03-01

Herein, for the first time, we demonstrate the fabrication of Fe2O3@LiCoO2 hybrid nanostructures on Ni foam substrate by facile one-step hydrothermal technique. Morphological studies reveal that aggregated Fe2O3 nanoflakes anchored on the surface of sphere-like LiCoO2 nanoflakes. Electrochemical studies are used to examine the performance of the supercapacitor electrodes. The composite Fe2O3@LiCoO2 electrode exhibited excellent electrochemical performance than Fe2O3 and LiCoO2 electrodes, such as a low charge transfer resistance, a high specific capacitance of 489 F g-1 at 5 mA cm-2 and an enhanced capacity retention of 108% over 3000 cycles at 15 mA cm-2. The composite Fe2O3@LiCoO2 holds great promise for electrochemical applications due to well-defined hierarchical morphology, synergetic effect of Fe2O3 and LiCoO2, enhanced electrical conductivity, efficient electrolyte penetration and fast electron transfer.

Metal Ir coatings on endocardial electrode tips, obtained by MOCVD

NASA Astrophysics Data System (ADS)

Vikulova, Evgeniia S.; Kal'nyi, Danila B.; Shubin, Yury V.; Kokovkin, Vasily V.; Morozova, Natalya B.; Hassan, Aseel; Basova, Tamara V.

2017-12-01

The present work demonstrates the application of the Metal-Organic Chemical Vapor Deposition technique to fabricate metal iridium coatings onto the pole tips of endocardial electrodes. Using iridium (III) acetylacetonate as a volatile precursor, the target coatings were successfully applied to the working surface of cathodes and anodes of pacemaker electrodes in the flow type reactor in hydrogen atmosphere at deposition temperature of 550 °C. The coating samples were characterized by means of XRD, SEM, Raman- and XPS-spectroscopies. The formation of non-textured coatings with fractal-like morphology and 7-24 nm crystallite size has been realized. The electrochemical properties of the coatings were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The charge storage capacity values of the electrochemically activated samples were 17.0-115 mC cm-2 and 14.4-76.5 mC cm-2 for measurements carried out in 0.1 M sulfuric acid and in phosphate buffer saline solutions, respectively. A comparison of some characteristics of the samples obtained with commercially available cathode of pacemaker electrodes is also presented.

Electrochemical camera chip for simultaneous imaging of multiple metabolites in biofilms

PubMed Central

Bellin, Daniel L.; Sakhtah, Hassan; Zhang, Yihan; Price-Whelan, Alexa; Dietrich, Lars E. P.; Shepard, Kenneth L.

2016-01-01

Monitoring spatial distribution of metabolites in multicellular structures can enhance understanding of the biochemical processes and regulation involved in cellular community development. Here we report on an electrochemical camera chip capable of simultaneous spatial imaging of multiple redox-active phenazine metabolites produced by Pseudomonas aeruginosa PA14 colony biofilms. The chip features an 8 mm × 8 mm array of 1,824 electrodes multiplexed to 38 parallel output channels. Using this chip, we demonstrate potential-sweep-based electrochemical imaging of whole-biofilms at measurement rates in excess of 0.2 s per electrode. Analysis of mutants with various capacities for phenazine production reveals distribution of phenazine-1-carboxylic acid (PCA) throughout the colony, with 5-methylphenazine-1-carboxylic acid (5-MCA) and pyocyanin (PYO) localized to the colony edge. Anaerobic growth on nitrate confirms the O2-dependence of PYO production and indicates an effect of O2 availability on 5-MCA synthesis. This integrated-circuit-based technique promises wide applicability in detecting redox-active species from diverse biological samples. PMID:26813638

CheapStat: an open-source, "do-it-yourself" potentiostat for analytical and educational applications.

PubMed

Rowe, Aaron A; Bonham, Andrew J; White, Ryan J; Zimmer, Michael P; Yadgar, Ramsin J; Hobza, Tony M; Honea, Jim W; Ben-Yaacov, Ilan; Plaxco, Kevin W

2011-01-01

Although potentiostats are the foundation of modern electrochemical research, they have seen relatively little application in resource poor settings, such as undergraduate laboratory courses and the developing world. One reason for the low penetration of potentiostats is their cost, as even the least expensive commercially available laboratory potentiostats sell for more than one thousand dollars. An inexpensive electrochemical workstation could thus prove useful in educational labs, and increase access to electrochemistry-based analytical techniques for food, drug and environmental monitoring. With these motivations in mind, we describe here the CheapStat, an inexpensive (<$80), open-source (software and hardware), hand-held potentiostat that can be constructed by anyone who is proficient at assembling circuits. This device supports a number of potential waveforms necessary to perform cyclic, square wave, linear sweep and anodic stripping voltammetry. As we demonstrate, it is suitable for a wide range of applications ranging from food- and drug-quality testing to environmental monitoring, rapid DNA detection, and educational exercises. The device's schematics, parts lists, circuit board layout files, sample experiments, and detailed assembly instructions are available in the supporting information and are released under an open hardware license.

Binder-free cobalt phosphate one-dimensional nanograsses as ultrahigh-performance cathode material for hybrid supercapacitor applications

NASA Astrophysics Data System (ADS)

Sankar, K. Vijaya; Lee, S. C.; Seo, Y.; Ray, C.; Liu, S.; Kundu, A.; Jun, S. C.

2018-01-01

One-dimensional (1D) nanostructure exhibits excellent electrochemical performance because of their unique physico-chemical properties like fast electron transfer, good rate capability, and cyclic stability. In the present study, Co3(PO4)2 1D nanograsses are grown on Ni foam using a simple and eco-friendly hydrothermal technique with different reaction times. The open space with uniform nanograsses displays a high areal capacitance, rate capability, energy density, and cyclic stability due to the nanostructure enhancing fast ion and material interactions. Ex-situ microscope images confirm the dependence of structural stability on the reaction time, and the nanograsses promoted ion interaction through material. Further, the reproducibility of the electrochemical performance confirms the binder-free Co3(PO4)2 1D nanograsses to be a suitable high-performance cathode material for application to hybrid supercapacitor. Finally, the assembled hybrid supercapacitor exhibits a high energy density (26.66 Wh kg-1 at 750 W kg-1) and longer lifetimes (80% retained capacitance after 6000 cycles). Our results suggests that the Co3(PO4)2 1D nanograss design have a great promise for application to hybrid supercapacitor.

CheapStat: An Open-Source, “Do-It-Yourself” Potentiostat for Analytical and Educational Applications

PubMed Central

Rowe, Aaron A.; Bonham, Andrew J.; White, Ryan J.; Zimmer, Michael P.; Yadgar, Ramsin J.; Hobza, Tony M.; Honea, Jim W.; Ben-Yaacov, Ilan; Plaxco, Kevin W.

2011-01-01

Although potentiostats are the foundation of modern electrochemical research, they have seen relatively little application in resource poor settings, such as undergraduate laboratory courses and the developing world. One reason for the low penetration of potentiostats is their cost, as even the least expensive commercially available laboratory potentiostats sell for more than one thousand dollars. An inexpensive electrochemical workstation could thus prove useful in educational labs, and increase access to electrochemistry-based analytical techniques for food, drug and environmental monitoring. With these motivations in mind, we describe here the CheapStat, an inexpensive (<$80), open-source (software and hardware), hand-held potentiostat that can be constructed by anyone who is proficient at assembling circuits. This device supports a number of potential waveforms necessary to perform cyclic, square wave, linear sweep and anodic stripping voltammetry. As we demonstrate, it is suitable for a wide range of applications ranging from food- and drug-quality testing to environmental monitoring, rapid DNA detection, and educational exercises. The device's schematics, parts lists, circuit board layout files, sample experiments, and detailed assembly instructions are available in the supporting information and are released under an open hardware license. PMID:21931613

Nanomaterials for Electrochemical Immunosensing

PubMed Central

Pan, Mingfei; Gu, Ying; Yun, Yaguang; Li, Min; Jin, Xincui; Wang, Shuo

2017-01-01

Electrochemical immunosensors resulting from a combination of the traditional immunoassay approach with modern biosensors and electrochemical analysis constitute a current research hotspot. They exhibit both the high selectivity characteristics of immunoassays and the high sensitivity of electrochemical analysis, along with other merits such as small volume, convenience, low cost, simple preparation, and real-time on-line detection, and have been widely used in the fields of environmental monitoring, medical clinical trials and food analysis. Notably, the rapid development of nanotechnology and the wide application of nanomaterials have provided new opportunities for the development of high-performance electrochemical immunosensors. Various nanomaterials with different properties can effectively solve issues such as the immobilization of biological recognition molecules, enrichment and concentration of trace analytes, and signal detection and amplification to further enhance the stability and sensitivity of the electrochemical immunoassay procedure. This review introduces the working principles and development of electrochemical immunosensors based on different signals, along with new achievements and progress related to electrochemical immunosensors in various fields. The importance of various types of nanomaterials for improving the performance of electrochemical immunosensor is also reviewed to provide a theoretical basis and guidance for the further development and application of nanomaterials in electrochemical immunosensors. PMID:28475158

Synthesis and characterization of prospective polyanionic electrode materials for high performance energy storage applications

NASA Astrophysics Data System (ADS)

Jayachandran, M.; Durai, G.; Vijayakumar, T.

2018-04-01

In the present study, Polyanionic compound (SO4)-group based on Li2Ni(SO4)2 (Lithium Nickel Sulphate) composite electrodes materials were prepared by a ball-milling method and solid-state reaction route. X-ray diffraction analysis confirmed the formation of a polycrystalline orthorhombic phase of composite Li2Ni(SO4)2 with an average crystallite size of about 50.16 nm. Field Emission Scanning electron microscopy investigation reveals the spherical shape particles with the particle size of around 200–500 nm. Raman and FTIR analysis confirms the structural and functional groups of the synthesized materials and also the formation of Li2Ni(SO4)2. The electrochemical measurements using cyclic voltammetry (CV) and galvanostatic charging-discharging (GCD) techniques were carried out to study the electrochemical supercapacitive performance of the composite Li2Ni (SO4)2 electrodes. From the CV investigations, an areal capacitance of 508 mF cm‑2 was obtained at 10 mV s‑1. The galvanostatic charge-discharge (GCD) measurements exhibited the areal capacitance of 101 mF cm‑2 at a constant current density of 2 mA cm‑2 in 2 M KOH. These GCD profiles were linear and also symmetric in nature with the maximum columbic efficiency of about 85%. The electrochemical performance of the composite Li2Ni(SO4)2 electrode material shows excellent performance for supercapacitor applications.

Quasi-monodimensional polyaniline nanostructures for enhanced molecularly imprinted polymer-based sensing.

PubMed

Berti, Francesca; Todros, Silvia; Lakshmi, Dhana; Whitcombe, Michael J; Chianella, Iva; Ferroni, Matteo; Piletsky, Sergey A; Turner, Anthony P F; Marrazza, Giovanna

2010-10-15

Recent advances in nanotechnology have allowed significant progress in utilising cutting-edge techniques associated with nanomaterials and nano-fabrication to expand the scope and capability of biosensors to a new level of novelty and functionality. The aim of this work was the development and characterisation of conductive polyaniline (PANI) nanostructures for applications in electrochemical biosensing. We explore a simple, inexpensive and fast route to grow PANI nanotubes, arranged in an ordered structure directly on an electrode surface, by electrochemical polymerisation using alumina nanoporous membranes as a 'nano-mould'. The deposited nanostructures have been characterised electrochemically and morphologically prior to grafting with a molecularly imprinted polymer (MIP) receptor in order to create a model sensor for catechol detection. In this way, PANI nanostructures resulted in a conductive nanowire system which allowed direct electrical connection between the electrode and the synthetic receptor (MIP). To our knowledge, this is the first example of integration between molecularly imprinted polymers and PANI nanostructured electrodes. The advantages of using nanostructures in this particular biosensing application have been evaluated by comparing the analytical performance of the sensor with an analogous non-nanostructured MIP-sensor for catechol detection that was previously developed. A significantly lower limit of detection for catechol has been obtained (29 nM, one order of magnitude), thus demonstrating that the nanostructures are capable of improving the analytical performance of the sensor. Copyright © 2010 Elsevier B.V. All rights reserved.

An innovative architectural design to enhance the electrochemical performance of La2NiO4+δ cathodes for solid oxide fuel cell applications

NASA Astrophysics Data System (ADS)

Sharma, Rakesh K.; Burriel, Mónica; Dessemond, Laurent; Martin, Vincent; Bassat, Jean-Marc; Djurado, Elisabeth

2016-06-01

An architectural design of the cathode microstructure based on combining electrostatic spray deposition (ESD) and screen-printing (SP) techniques has demonstrated to be an innovative strategy to enhance the electrochemical properties of La2NiO4+δ (LNO) as oxygen electrode on Ce0.9Gd0.1O2-δ (CGO) electrolyte for solid oxide fuel cells. For this purpose, the influence of the ESD process parameters on the microstructure has been systematically investigated. Electrochemical performances of four selected cathode microstructures are investigated: (i) 3-D coral nanocrystalline (average particle size ∼ 100 nm) LNO film grown by ESD; (ii) 3-D coral nanocrystalline film (average particle size ∼ 150 nm) grown by ESD with a continuous nanometric dense interface; (iii) porous screen-printed LNO film (average particle size ∼ 400 nm); and (iv) 3-D coral nanocrystalline film (average particle size ∼ 150 nm) with a continuous nanometric dense interface prepared by ESD topped by a LNO current collector prepared by SP. A significant reduction in the polarization resistance (Rpol) is obtained (0.08 Ω cm2 at 700 °C) for 3-D coral topped by the SP layer. Moreover LNO is found to be stable and compatible with CGO up to 800 °C for only 10 days duration in air, making it potentially suitable for SOFCs cathode application.

Tailoring the Electrochemical Properties of Carbon Nanotube Modified Indium Tin Oxide via in Situ Grafting of Aryl Diazonium.

PubMed

Hicks, Jacqueline M; Wong, Zhi Yi; Scurr, David J; Silman, Nigel; Jackson, Simon K; Mendes, Paula M; Aylott, Jonathan W; Rawson, Frankie J

2017-05-23

Our ability to tailor the electronic properties of surfaces by nanomodification is paramount for various applications, including development of sensing, fuel cell, and solar technologies. Moreover, in order to improve the rational design of conducting surfaces, an improved understanding of structure/function relationships of nanomodifications and effect they have on the underlying electronic properties is required. Herein, we report on the tuning and optimization of the electrochemical properties of indium tin oxide (ITO) functionalized with single-walled carbon nanotubes (SWCNTs). This was achieved by controlling in situ grafting of aryl amine diazonium films on the nanoscale which were used to covalently tether SWCNTs. The structure/function relationship of these nanomodifications on the electronic properties of ITO was elucidated via time-of-flight secondary ion mass spectrometry and electrochemical and physical characterization techniques which has led to new mechanistic insights into the in situ grafting of diazonium. We discovered that the connecting bond is a nitro group which is covalently linked to a carbon on the aryl amine. The increased understanding of the surface chemistry gained through these studies enabled us to fabricate surfaces with optimized electron transfer kinetics. The knowledge gained from these studies allows for the rational design and tuning of the electronic properties of ITO-based conducting surfaces important for development of various electronic applications.

Structures And Fabrication Techniques For Solid State Electrochemical Devices

DOEpatents

Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

2005-12-27

Provided are low-cost, mechanically strong, highly electronically conductive porous substrates and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical device substrates of novel composition and techniques for forming thin electrode/membrane/electrolyte coatings on the novel or more conventional substrates. In particular, in one embodiment the invention provides techniques for co-firing of device substrate (often an electrode) with an electrolyte or membrane layer to form densified electrolyte/membrane films 5 to 20 microns thick. In another embodiment, densified electrolyte/membrane films 5 to 20 microns thick may be formed on a pre-sintered substrate by a constrained sintering process. In some cases, the substrate may be a porous metal, alloy, or non-nickel cermet incorporating one or more of the transition metals Cr, Fe, Cu and Ag, or alloys thereof.

Structures and fabrication techniques for solid state electrochemical devices

DOEpatents

Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

2003-08-12

Provided are low-cost, mechanically strong, highly electronically conductive porous substrates and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical device substrates of novel composition and techniques for forming thin electrode/membrane/electrolyte coatings on the novel or more conventional substrates. In particular, in one embodiment the invention provides techniques for co-firing of device substrate (often an electrode) with an electrolyte or membrane layer to form densified electrolyte/membrane films 5 to 20 microns thick. In another embodiment, densified electrolyte/membrane films 5 to 20 microns thick may be formed on a pre-sintered substrate by a constrained sintering process. In some cases, the substrate may be a porous metal, alloy, or non-nickel cermet incorporating one or more of the transition metals Cr, Fe, Cu and Ag, or alloys thereof.

Magnetic nanomotor fabrication by plasma coating method and its biological application

NASA Astrophysics Data System (ADS)

Oksuz, Lutfi; Yurdabak Karaca, Gozde; Uygun, Emre; Uygun Oksuz, Aysegul

2017-10-01

Nano/micro scale motors are exciting research area due to a wide range of application area especially offer considerable promise for the diagnosis and treatment of the diseases. In this scope, the preparation and characterization of Gold (Au)/ Nickel (Ni) nanomotors transport and their applications based on the detection of miRNA-21 will be examined. In addition, magnetic segment Ni which was coated by RF magnetron sputter technique on to the electrochemical synthesized Au nanowire can also be used to focus on the controlled movement and target. We propose a sensitive stable plasma coated magnetic nanomotor-based approach for miRNA-21 detection for simple and cancer diagnosis.

Characterization of Nanopipettes.

PubMed

Perry, David; Momotenko, Dmitry; Lazenby, Robert A; Kang, Minkyung; Unwin, Patrick R

2016-05-17

Nanopipettes are widely used in electrochemical and analytical techniques as tools for sizing, sequencing, sensing, delivery, and imaging. For all of these applications, the response of a nanopipette is strongly affected by its geometry and surface chemistry. As the size of nanopipettes becomes smaller, precise geometric characterization is increasingly important, especially if nanopipette probes are to be used for quantitative studies and analysis. This contribution highlights the combination of data from voltage-scanning ion conductivity experiments, transmission electron microscopy and finite element method simulations to fully characterize nanopipette geometry and surface charge characteristics, with an accuracy not achievable using existing approaches. Indeed, it is shown that presently used methods for characterization can lead to highly erroneous information on nanopipettes. The new approach to characterization further facilitates high-level quantification of the behavior of nanopipettes in electrochemical systems, as demonstrated herein for a scanning ion conductance microscope setup.

High-performance flexible electrode based on electrodeposition of polypyrrole/MnO2 on carbon cloth for supercapacitors

NASA Astrophysics Data System (ADS)

Fan, Xingye; Wang, Xiaolei; Li, Ge; Yu, Aiping; Chen, Zhongwei

2016-09-01

A highly flexible electrodes based on electrodeposited MnO2 and polypyrrole composite on carbon cloth is designed and developed by a facile in-situ electrodeposition technique. Such flexible composite electrodes with multiply layered structure possess a high specific capacitance of 325 F g-1 at a current density of 0.2 A g-1, and an excellent rate capability with a capacitance retention of 70% at a high current density of 5.0 A g-1. The superior electrochemical performance is mainly due to the unique electrode with improved ion- and electron-transportation pathways as well as the efficient utilization of active materials and electrode robustness. The excellent electrochemical performance and the low cost property endow this flexible nanocomposite electrode with great promise in applications of flexible supercapacitors.

Carbon coated textiles for flexible energy storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jost, Kristy; Perez, Carlos R.; McDonough, John K.

This paper describes a flexible and lightweight fabric supercapacitor electrode as a possible energy source in smart garments. We examined the electrochemical behavior of porous carbon materials impregnated into woven cotton and polyester fabrics using a traditional printmaking technique (screen printing). The porous structure of such fabrics makes them attractive for supercapacitor applications that need porous films for ion transfer between electrodes. We used cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy to study the capacitive behaviour of carbon materials using nontoxic aqueous electrolytes including sodium sulfate and lithium sulfate. Electrodes coated with activated carbon (YP17) and tested at ~0.25more » A·g⁻¹ achieved a high gravimetric and areal capacitance, an average of 85 F·g⁻¹ on cotton lawn and polyester microfiber, both corresponding to ~0.43 F·cm⁻².« less

Carbon coated textiles for flexible energy storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jost, Kristy; Perez, Carlos O; Mcdonough, John

This paper describes a flexible and lightweight fabric supercapacitor electrode as a possible energy source in smart garments. We examined the electrochemical behavior of porous carbon materials impregnated into woven cotton and polyester fabrics using a traditional printmaking technique (screen printing). The porous structure of such fabrics makes them attractive for supercapacitor applications that need porous films for ion transfer between electrodes. We used cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy to study the capacitive behaviour of carbon materials using nontoxic aqueous electrolytes including sodium sulfate and lithium sulfate. Electrodes coated with activated carbon (YP17) and tested at 0.25more » A$g1 achieved a high gravimetric and areal capacitance, an average of 85 F$g1 on cotton lawn and polyester microfiber, both corresponding to 0.43 F$cm2.« less

Biosensor for detection of dissolved chromium in potable water: A review.

PubMed

Biswas, Puja; Karn, Abhinav Kumar; Balasubramanian, P; Kale, Paresh G

2017-08-15

The unprecedented deterioration rate of the environmental quality due to rapid urbanization and industrialization causes a severe global health concern to both ecosystem and humanity. Heavy metals are ubiquitous in nature and being used extensively in industrial processes, the exposure to excessive levels could alter the biochemical cycles of living systems. Hence the environmental monitoring through rapid and specific detection of heavy metal contamination in potable water is of paramount importance. Various standard analytical techniques and sensors are used for the detection of heavy metals include spectroscopy and chromatographic methods along with electrochemical, optical waveguide and polymer based sensors. However, the mentioned techniques lack the point of care application as it demands huge capital cost as well as the attention of expert personnel for sample preparation and operation. Recent advancements in the synergetic interaction among biotechnology and microelectronics have advocated the biosensor technology for a wide array of applications due to its characteristic features of sensitivity and selectivity. This review paper has outlined the overview of chromium toxicity, conventional analytical techniques along with a particular emphasis on electrochemical based biosensors for chromium detection in potable water. This article emphasized porous silicon as a host material for enzyme immobilization and elaborated the working principle, mechanism, kinetics of an enzyme-based biosensor for chromium detection. The significant characteristics such as pore size, thickness, and porosity make the porous silicon suitable for enzyme entrapment. Further, several schemes on porous silicon-based immobilized enzyme biosensors for the detection of chromium in potable water are proposed. Copyright © 2017 Elsevier B.V. All rights reserved.

A brief review on recent developments of electrochemical sensors in environmental application for PGMs.

PubMed

Silwana, Bongiwe; Van Der Horst, Charlton; Iwuoha, Emmanuel; Somerset, Vernon

2016-12-05

This study offers a brief review of the latest developments and applications of electrochemical sensors for the detection of Platinum Group Metals (PGMs) using electrochemical sensors. In particular, significant advances in electrochemical sensors made over the past decade and sensing methodologies associated with the introduction of nanostructures are highlighted. Amongst a variety of detection methods that have been developed for PGMs, nanoparticles offer the unrivaled merits of high sensitivity. Rapid detection of PGMs is a key step to promote improvement of the public health and individual quality of life. Conventional methods to detect PGMs rely on time-consuming and labor intensive procedures such as extraction, isolation, enrichment, counting, etc., prior to measurement. This results in laborious sample preparation and testing over several days. This study reviewed the state-of-the-art application of nanoparticles (NPs) in electrochemical analysis of environmental pollutants. This review is intended to provide environmental scientists and engineers an overview of current rapid detection methods, a close look at the nanoparticles based electrodes and identification of knowledge gaps and future research needs. We summarize electrodes that have been used in the past for detection of PGMs. We describe several examples of applications in environmental electrochemical sensors and performance in terms of sensitivity and selectivity for all the sensors utilized for PGMs detection. NPs have promising potential to increase competitiveness of electrochemical sensors in environmental monitoring, though this review has focused mainly on sensors used in the past decade for PGMs detection. This review therefore provides a synthesis of outstanding performances in recent advances in the nanosensor application for PGMs determination.

Anodic electrochemical performances of MgCo{sub 2}O{sub 4} synthesized by oxalate decomposition method and electrospinning technique for Li-ion battery application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darbar, Devendrasinh; Department of Mechanical Engineering, National University of Singapore, 117576; Department of Physics, National University of Singapore, 117542

2016-01-15

Highlights: • MgCo{sub 2}O{sub 4} was prepared by oxalate decomposition method and electrospinning technique. • Electrospun MgCo{sub 2}O{sub 4} shows the reversible capacity of 795 and 227 mAh g{sup −1} oxalate decomposition MgCo{sub 2}O{sub 4} after 50 cycle. • Electrospun MgCo{sub 2}O{sub 4} show good cycling stability and electrochemical performance. - Abstract: Magnesium cobalt oxide, MgCo{sub 2}O{sub 4} was synthesized by oxalate decomposition method and electrospinning technique. The electrochemical performances, structures, phase formation and morphology of MgCo{sub 2}O{sub 4} synthesized by both the methods are compared. Scanning electron microscope (SEM) studies show spherical and fiber type morphology, respectively for themore » oxalate decomposition and electrospinning method. The electrospun nanofibers of MgCo{sub 2}O{sub 4} calcined at 650 °C, showed a very good reversible capacity of 795 mAh g{sup −1} after 50 cycles when compared to bulk material capacity of 227 mAh g{sup −1} at current rate of 60 mA g{sup −1}. MgCo{sub 2}O{sub 4} nanofiber showed a reversible capacity of 411 mAh g{sup −1} (at cycle) at current density of 240 mA g{sup −1}. Improved performance was due to improved conductivity of MgO, which may act as buffer layer leading to improved cycling stability. The cyclic voltammetry studies at scan rate of 0.058 mV/s show main cathodic at around 1.0 V and anodic peaks at 2.1 V vs. Li.« less

Nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel and stainless steel alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, D.G.; Sorensen, N.R.

1998-02-01

This report presents a nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel alloys from stainless steel alloys as well as an evaluation of cleaning techniques to remove a thermal oxide layer on aircraft exhaust components. The results of this assessment are presented in terms of how effective each technique classifies a known exhaust material. Results indicate that either inspection technique can separate inconel and stainless steel alloys. Based on the experiments conducted, the electrochemical spot test is the optimum for use by airframe and powerplant mechanics. A spot test procedure is proposed for incorporation into themore » Federal Aviation Administration Advisory Circular 65-9A Airframe & Powerplant Mechanic - General Handbook. 3 refs., 70 figs., 7 tabs.« less

Electrochemical synthesis of poly(pyrrole-co-o-anisidine)/chitosan composite films

NASA Astrophysics Data System (ADS)

Yalçınkaya, Süleyman; Çakmak, Didem

2017-05-01

In this study, poly(pyrrole-co-o-anisidine)/chitosan composite films were electrochemically synthesized in various monomers feed ratio (pyrrole: o-anisidine; 9:1, 7:3, 1:1, 3:7 and 1:9) of pyrrole and o-anisidine on the platinum electrode. Electrochemical synthesis of the composite films was carried out via cyclic voltammetry technique. They were characterized by FT-IR, cyclic voltammetry, SEM micrographs, digital images, TGA and DSC techniques. The SEM results indicated that the particle size of the composite decreased with increasing o-anisidine ratio and the films became more likely to be smooth morphology. The TGA results proved that the film of the composite with 1:1 ratio showed highest final degradation temperature and lowest weight loss (83%) compared to copolymer and 9:1 1:9 composite films. The 1:1 composite film had higher thermal stability than copolymer and the other composite films (9:1 1:9). Meanwhile, electrochemical studies exhibited that the 1/9 composite film had good electrochemical stability as well.

A literature review of in situ transmission electron microscopy technique in corrosion studies.

PubMed

Song, Zhengwei; Xie, Zhi-Hui

2018-06-18

One of the biggest challenges in corrosion investigation is foreseeing precisely how and where materials will degenerate in a designated condition owing to scarceness of accurate corrosion mechanisms. Recent fast development of in situ transmission electron microscopy (TEM) technique makes it achievable to better understand the corrosion mechanism and physicochemical processes at the interfaces between samples and gases or electrolytes by dynamical capture the microstructural and chemical changes with high resolution within a realistic or near-realistic environment. However, a detailed and in-depth account summing up the development and latest achievements of in situ TEM techniques, especially the application of emerging liquid and electrochemical cells in the community of corrosion study in the last several years is lacking and is urgently needed for its heathy development. To fill this gap, this critical review summarizes firstly the key scientific issues in corrosion research, followed by introducing the configurations of several typical closed-type cells. Then, the achievements of in situ TEM using open-type or closed-type cells in corrosion study are presented in detail. The study directions in the future are commented finally in terms of spatial and temporal resolution, electron radiation, and linkage between microstructure and electrochemical performance in corrosion community. Copyright © 2018 Elsevier Ltd. All rights reserved.

An electrochemical and structural study of highly uniform tin oxide nanowires fabricated by a novel, scalable solvoplasma technique as anode material for sodium ion batteries

NASA Astrophysics Data System (ADS)

Mukherjee, Santanu; Schuppert, Nicholas; Bates, Alex; Jasinski, Jacek; Hong, Jong-Eun; Choi, Moon Jong; Park, Sam

2017-04-01

A novel solvoplasma based technique was used to fabricate highly uniform SnO2 nanowires (NWs) for application as an anode in sodium-ion batteries (SIBs). This technique is scalable, rapid, and utilizes a rigorous cleaning process to produce very pure SnO2 NWs with enhanced porosity; which improves sodium-ion hosting and reaction kinetics. The batch of NWs obtained from the plasma process were named the "as-made" sample and after cleaning the "pure" sample. Structural characterization showed that the as-made sample has a K+ ion impurity which is absent in the pure samples. The pure samples have a higher maximum specific capacity, 400.71 mAhg-1, and Coulombic efficiency, 85%, compared to the as-made samples which have a maximum specific capacity of 174.69 mAhg-1 and Coulombic efficiency of 74% upon cycling. A study of the electrochemical impedance spectra showed that the as-made samples have a higher interfacial and diffusion resistance than the pure samples and resistances increased after 50 cycles of cell operation for both samples due to progressive electrode degradation. Specific energy vs specific power plots were employed to analyze the performance of the system with respect to the working conditions.

Development of intraoperative electrochemical detection: wireless instantaneous neurochemical concentration sensor for deep brain stimulation feedback

PubMed Central

Van Gompel, Jamie J.; Chang, Su-Youne; Goerss, Stephan J.; Kim, In Yong; Kimble, Christopher; Bennet, Kevin E.; Lee, Kendall H.

2010-01-01

Deep brain stimulation (DBS) is effective when there appears to be a distortion in the complex neurochemical circuitry of the brain. Currently, the mechanism of DBS is incompletely understood; however, it has been hypothesized that DBS evokes release of neurochemicals. Well-established chemical detection systems such as microdialysis and mass spectrometry are impractical if one is assessing changes that are happening on a second-to-second time scale or for chronically used implanted recordings, as would be required for DBS feedback. Electrochemical detection techniques such as fast-scan cyclic voltammetry (FSCV) and amperometry have until recently remained in the realm of basic science; however, it is enticing to apply these powerful recording technologies to clinical and translational applications. The Wireless Instantaneous Neurochemical Concentration Sensor (WINCS) currently is a research device designed for human use capable of in vivo FSCV and amperometry, sampling at subsecond time resolution. In this paper, the authors review recent advances in this electrochemical application to DBS technologies. The WINCS can detect dopamine, adenosine, and serotonin by FSCV. For example, FSCV is capable of detecting dopamine in the caudate evoked by stimulation of the subthalamic nucleus/substantia nigra in pig and rat models of DBS. It is further capable of detecting dopamine by amperometry and, when used with enzyme linked sensors, both glutamate and adenosine. In conclusion, WINCS is a highly versatile instrument that allows near real-time (millisecond) detection of neurochemicals important to DBS research. In the future, the neurochemical changes detected using WINCS may be important as surrogate markers for proper DBS placement as well as the sensor component for a “smart” DBS system with electrochemical feedback that allows automatic modulation of stimulation parameters. Current work is under way to establish WINCS use in humans. PMID:20672923

Electrochemically reduced graphene oxide-modified screen-printed carbon electrodes for a simple and highly sensitive electrochemical detection of synthetic colorants in beverages.

PubMed

Jampasa, Sakda; Siangproh, Weena; Duangmal, Kiattisak; Chailapakul, Orawon

2016-11-01

A simple and highly sensitive electrochemical sensor based on an electrochemically reduced graphene oxide-modified screen-printed carbon electrode (ERGO-SPCE) for the simultaneous determination of sunset yellow (SY) and tartrazine (TZ) was proposed. An ERGO film was coated onto the electrode surface using a cyclic voltammetric method and then characterized by scanning electron microscopy (SEM). In 0.1M phosphate buffer at a pH of 6, the two oxidation peaks of SY and TZ appeared separately at 0.41 and 0.70V, respectively. Surprisingly, the electrochemical response remarkably increased approximately 90- and 20-fold for SY and TZ, respectively, using the modified electrode in comparison to the unmodified electrode. The calibration curves exhibited linear ranges from 0.01 to 20.0µM for SY and from 0.02 to 20.0µM for TZ. The limits of detection were found to be 0.50 and 4.50nM (at S/N=3) for SY and TZ, respectively. Furthermore, this detection platform provided very high selectivity for the measurement of both colorants. This electrochemical sensor was successfully applied to determine the amount of SY and TZ in commercial beverages. Comparison of the results obtained from this proposed method to those obtained by an in-house standard technique proved that this developed method has good agreement in terms of accuracy for practical applications. This sensor offers an inexpensive, rapid and sensitive determination. The proposed system is therefore suitable for routine analysis and should be an alternative method for the analysis of food colorants. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrochemical chloride extraction : influence of concrete surface on treatment.

DOT National Transportation Integrated Search

2002-10-01

One bridge restoration technique available for reducing corrosion-induced concrete deterioration, which removes : chloride ions while simultaneously realkalizing the concrete adjacent to the steel, is electrochemical chloride extraction : (ECE). Stud...

Electrochemical Chloride Extraction : Influence of Concrete Surface on Treatment

DOT National Transportation Integrated Search

2002-09-01

One bridge restoration technique available for reducing corrosion-induced concrete deterioration, which removes chloride ions while simultaneously realkalizing the concrete adjacent to the steel, is electrochemical chloride extraction (ECE). Studies ...

Engineering of Metal Oxide Nanoparticles for Application in Electrochemical Devices

NASA Astrophysics Data System (ADS)

Santos, Lidia Sofia Leitao

The growing demand for materials and devices with new functionalities led to the increased interest in the field of nanomaterials and nanotechnologies. Nanoparticles, not only present a reduced size as well as high reactivity, which allows the development of electronic and electrochemical devices with exclusive properties, when compared with thin films. This dissertation aims to explore the development of several nanostructured metal oxides by solvothermal synthesis and its application in different electrochemical devices. Within this broad theme, this study has a specific number of objectives: a) research of the influence of the synthesis parameters to the structure and morphology of the nanoparticles; b) improvement of the performance of the electrochromic devices with the application of the nanoparticles as electrode; c) application of the nanoparticles as probes to sensing devices; and d) production of solution-pro-cessed transistors with a nanostructured metal oxide semiconductor. Regarding the results, several conclusions can be exposed. Solvothermal synthesis shows to be a very versatile method to control the growth and morphology of the nanoparticles. The electrochromic device performance is influenced by the different structures and morphologies of WO3 nanoparticles, mainly due to the surface area and conductivity of the materials. The deposition of the electrochromic layer by inkjet printing allows the patterning of the electrodes without wasting material and without any additional steps. Nanostructured WO3 probes were produced by electrodeposition and drop casting and applied as pH sensor and biosensor, respectively. The good performance and sensitivity of the devices is explained by the high number of electrochemical reactions occurring at the surface of the na-noparticles. GIZO nanoparticles were deposited by spin coating and used in electrolyte-gated transistors, which promotes a good interface between the semiconductor and the dielectric. The produced transistors work at low potential and with improved ON-OFF current ratio, up to 6 orders of mag-nitude. To summarize, the low temperatures used in the production of the devices are compatible with flexible substrates and additionally, the low cost of the techniques involved can be adapted for disposable devices.

Solution synthesis of metal oxides for electrochemical energy storage applications.

PubMed

Xia, Xinhui; Zhang, Yongqi; Chao, Dongliang; Guan, Cao; Zhang, Yijun; Li, Lu; Ge, Xiang; Bacho, Ignacio Mínguez; Tu, Jiangping; Fan, Hong Jin

2014-05-21

This article provides an overview of solution-based methods for the controllable synthesis of metal oxides and their applications for electrochemical energy storage. Typical solution synthesis strategies are summarized and the detailed chemical reactions are elaborated for several common nanostructured transition metal oxides and their composites. The merits and demerits of these synthesis methods and some important considerations are discussed in association with their electrochemical performance. We also propose the basic guideline for designing advanced nanostructure electrode materials, and the future research trend in the development of high power and energy density electrochemical energy storage devices.

MnO2 prepared by hydrothermal method and electrochemical performance as anode for lithium-ion battery

PubMed Central

2014-01-01

Two α-MnO2 crystals with caddice-clew-like and urchin-like morphologies are prepared by the hydrothermal method, and their structure and electrochemical performance are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), galvanostatic cell cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The morphology of the MnO2 prepared under acidic condition is urchin-like, while the one prepared under neutral condition is caddice-clew-like. The identical crystalline phase of MnO2 crystals is essential to evaluate the relationship between electrochemical performances and morphologies for lithium-ion battery application. In this study, urchin-like α-MnO2 crystals with compact structure have better electrochemical performance due to the higher specific capacity and lower impedance. We find that the relationship between electrochemical performance and morphology is different when MnO2 material used as electrochemical supercapacitor or as anode of lithium-ion battery. For lithium-ion battery application, urchin-like MnO2 material has better electrochemical performance. PMID:24982603

Electrochemical impedimetric sensor based on molecularly imprinted polymers/sol-gel chemistry for methidathion organophosphorous insecticide recognition.

PubMed

Bakas, Idriss; Hayat, Akhtar; Piletsky, Sergey; Piletska, Elena; Chehimi, Mohamed M; Noguer, Thierry; Rouillon, Régis

2014-12-01

We report here a novel method to detect methidathion organophosphorous insecticides. The sensing platform was architected by the combination of molecularly imprinted polymers and sol-gel technique on inexpensive, portable and disposable screen printed carbon electrodes. Electrochemical impedimetric detection technique was employed to perform the label free detection of the target analyte on the designed MIP/sol-gel integrated platform. The selection of the target specific monomer by electrochemical impedimetric methods was consistent with the results obtained by the computational modelling method. The prepared electrochemical MIP/sol-gel based sensor exhibited a high recognition capability toward methidathion, as well as a broad linear range and a low detection limit under the optimized conditions. Satisfactory results were also obtained for the methidathion determination in waste water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Chemically Integrated Inorganic-Graphene Two-Dimensional Hybrid Materials for Flexible Energy Storage Devices.

PubMed

Peng, Lele; Zhu, Yue; Li, Hongsen; Yu, Guihua

2016-12-01

State-of-the-art energy storage devices are capable of delivering reasonably high energy density (lithium ion batteries) or high power density (supercapacitors). There is an increasing need for these power sources with not only superior electrochemical performance, but also exceptional flexibility. Graphene has come on to the scene and advancements are being made in integration of various electrochemically active compounds onto graphene or its derivatives so as to utilize their flexibility. Many innovative synthesis techniques have led to novel graphene-based hybrid two-dimensional nanostructures. Here, the chemically integrated inorganic-graphene hybrid two-dimensional materials and their applications for energy storage devices are examined. First, the synthesis and characterization of different kinds of inorganic-graphene hybrid nanostructures are summarized, and then the most relevant applications of inorganic-graphene hybrid materials in flexible energy storage devices are reviewed. The general design rules of using graphene-based hybrid 2D materials for energy storage devices and their current limitations and future potential to advance energy storage technologies are also discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon nanofibers wrapped with zinc oxide nano-flakes as promising electrode material for supercapacitors.

PubMed

Pant, Bishweshwar; Park, Mira; Ojha, Gunendra Prasad; Park, Juhyeong; Kuk, Yun-Su; Lee, Eun-Jung; Kim, Hak-Yong; Park, Soo-Jin

2018-07-15

A combination of electrospinning technique and hydrothermal process was carried out to fabricate zinc oxide nano-flakes wrapped carbon nanofibers (ZnO/CNFs) composite as an effective electrode material for supercapacitor. The morphology of the as-synthesized composite clearly revealed that the carbon nanofibers were successfully wrapped with ZnO nano-flakes. The electrochemical performance of the as-synthesized nanocomposite electrode was evaluated by the cyclic voltammetry (CV), galvanostatic charge-discharge (GDC), and electrochemical impedance spectroscopy (EIS), and compared with the pristine ZnO nanofibers. It was found that the composite exhibited a higher specific capacitance (260 F/g) as compared to pristine ZnO NFs (118 F/g) at the scan rate of 5 mV/s. Furthermore, the ZnO/CNFs composite also exhibited good capacity retention (73.33%). The obtained results indicated great potential applications of ZnO/CNFs composite in developing energy storage devices with high energy and power densities. The present work might provide a new route for utilizing ZnO based composites for energy storage applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Preparation of highly porous binderless activated carbon electrodes from fibres of oil palm empty fruit bunches for application in supercapacitors.

PubMed

Farma, R; Deraman, M; Awitdrus, A; Talib, I A; Taer, E; Basri, N H; Manjunatha, J G; Ishak, M M; Dollah, B N M; Hashmi, S A

2013-03-01

Fibres from oil palm empty fruit bunches, generated in large quantities by palm oil mills, were processed into self-adhesive carbon grains (SACG). Untreated and KOH-treated SACG were converted without binder into green monolith prior to N2-carbonisation and CO2-activation to produce highly porous binderless carbon monolith electrodes for supercapacitor applications. Characterisation of the pore structure of the electrodes revealed a significant advantage from combining the chemical and physical activation processes. The electrochemical measurements of the supercapacitor cells fabricated using these electrodes, using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge techniques consistently found that approximately 3h of activation time, achieved via a multi-step heating profile, produced electrodes with a high surface area of 1704m(2)g(-1) and a total pore volume of 0.889cm(3)g(-1), corresponding to high values for the specific capacitance, specific energy and specific power of 150Fg(-1), 4.297Whkg(-1) and 173Wkg(-1), respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

In vitro corrosion study by EIS of a nickel-free stainless steel for orthopaedic applications.

PubMed

Rondelli, G; Torricelli, P; Fini, M; Giardino, R

2005-03-01

The electrochemical impedance spectroscopy (EIS) technique was used for the study of the electrochemical behaviour of Ni-free austenitic stainless steel for orthopaedic applications. Experiments were carried out using four different test solutions: (i) phosphate-buffered saline (PBS), (ii) minimum essential medium (MEM), (iii) MEM + 10% fetal calf serum (FCS), (iv) MEM + 10% fetal calf serum + L929 fibroblast cell line (Cell). Bode-phase spectra showed the presence of two maxima and were fitted with an equivalent circuit characterized by two parallel combinations (Resistance, Constant Phase Element). The (R(1), CPE(1)) branch was assigned to the inner compact passive film and the (R(2), CPE(2)) branch to the external porous film. The resistance of the inner film R(1), here directly related to the material's uniform corrosion resistance, raised with the immersion time and increased in the following order: PBS

Parallel Electrochemical Treatment System and Application for Identifying Acid-Stable Oxygen Evolution Electrocatalysts

DOE PAGES

Jones, Ryan J. R.; Shinde, Aniketa; Guevarra, Dan; ...

2015-01-05

There are many energy technologies require electrochemical stability or preactivation of functional materials. Due to the long experiment duration required for either electrochemical preactivation or evaluation of operational stability, parallel screening is required to enable high throughput experimentation. We found that imposing operational electrochemical conditions to a library of materials in parallel creates several opportunities for experimental artifacts. We discuss the electrochemical engineering principles and operational parameters that mitigate artifacts int he parallel electrochemical treatment system. We also demonstrate the effects of resistive losses within the planar working electrode through a combination of finite element modeling and illustrative experiments. Operationmore » of the parallel-plate, membrane-separated electrochemical treatment system is demonstrated by exposing a composition library of mixed metal oxides to oxygen evolution conditions in 1M sulfuric acid for 2h. This application is particularly important because the electrolysis and photoelectrolysis of water are promising future energy technologies inhibited by the lack of highly active, acid-stable catalysts containing only earth abundant elements.« less

Effect of various de-anodizing techniques on the surface stability of non-colored and colored nanoporous AAO films in acidic solution

NASA Astrophysics Data System (ADS)

Awad, Ahmed M.; Shehata, Omnia S.; Heakal, Fakiha El-Taib

2015-12-01

Anodic aluminum oxide (AAO) is well known as an important nanostructured material, and a useful template in the fabrication of nanostructures. Nanoporous anodic alumina (PAA) with high open porosity was prepared by adopting three de-anodizing regimes following the first anodizing step and preceding the second one. The de-anodizing methods include electrolytic etching (EE) and chemical etching using either phosphoric acid (PE) or sodium hydroxide (HE) solutions. Three of the obtained AAO samples were black colored by electrodeposition of copper nanoparticles in their pores. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques were used to characterize the electrochemical performance of the two sets of the prepared samples. In general, the data obtained in aggressive aerated 0.5 M HCl solution demonstrated dissimilar behavior for the three prepared samples despite that the second anodizing step was the same for all of them. The data indicated that the resistance and thickness of the inner barrier part of nano-PAA film, are the main controlling factors determining its stability. On the other hand, coloring the film decreased its stability due to the galvanic effect. The difference in the electrochemical behavior of the three colored samples was discussed based on the difference in both the pore size and thickness of the outer porous part of PAA film as supported by SEM, TEM and cross-sectional micrographs. These results can thus contribute for better engineering applications of nanoporous AAO.

Preliminary results of the comparison of the electrochemical behavior of a thioether and biphenyl

NASA Technical Reports Server (NTRS)

Morales, W.; Jones, W. R.

1983-01-01

An electrochemical cell was constructed to explore the feasibility of using electrochemical techniques to simulate the tribochemistry of various substances. The electrochemical cell was used to study and compare the behavior of a thioether 1,3-bis(phenylthio) benzene and biphenyl. It is found that under controlled conditions biphenyl undergoes a reversible reduction to a radical anion whereas the thioether undergoes an irreversible reduction yielding several products. The results are discussed in relationship to boundary lubrication.

Electrochemical Deposition of High Purity Silicon from Molten Salts

NASA Astrophysics Data System (ADS)

Haarberg, Geir Martin

Several approaches were tried in order to develop an electrochemical route for producing high purity silicon from molten salts. SiO2, K2SiF6 and metallurgical silicon were used as the source of silicon. Molten electrolytes based on chloride (CaCl2-NaCl) and fluoride (LiF-KF) at temperatures from 550 - 900 oC were used. Transient electrochemical techniques were used to study the electrochemical behaviour of dissolved silicon species. Electrolysis experiments were carried out to deposit silicon.

Electrochemical Deposition of High Purity Silicon in Molten Salts

NASA Astrophysics Data System (ADS)

Haarberg, Geir Martin

Several approaches were tried in order to develop an electrochemical route for producing high purity silicon from molten salts. SiO2, K2SiF6 and metallurgical silicon were used as the source of silicon. Molten electrolytes based on chloride (CaCl2-NaCl) and fluoride (LiF-KF) at temperatures from 550 - 900 °C were used. Transient electrochemical techniques were used to study the electrochemical behaviour of dissolved silicon species. Electrolysis experiments were carried out to deposit silicon.

Lateral electrochemical etching of III-nitride materials for microfabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Jung

Conductivity-selective lateral etching of III-nitride materials is described. Methods and structures for making vertical cavity surface emitting lasers with distributed Bragg reflectors via electrochemical etching are described. Layer-selective, lateral electrochemical etching of multi-layer stacks is employed to form semiconductor/air DBR structures adjacent active multiple quantum well regions of the lasers. The electrochemical etching techniques are suitable for high-volume production of lasers and other III-nitride devices, such as lasers, HEMT transistors, power transistors, MEMs structures, and LEDs.

A Comprehensive Pitting Study of High Velocity Oxygen Fuel Inconel 625 Coating by Using Electrochemical Testing Techniques

NASA Astrophysics Data System (ADS)

Niaz, Akbar; Khan, Sajid Ullah

2016-01-01

In the present work, Inconel 625 was coated on a mild steel substrate using a high velocity oxygen fuel coating process. The pitting propensity of the coating was tested by using open circuit potential versus time, potentiodynamic polarization, electrochemical potentiokinetic reactivation, and scanning electrochemical microscopy. The pitting propensity of the coating was compared with bulk Inconel 625 alloy. The results confirmed that there were regions of different electrochemical activities on the coating which have caused pitting corrosion.

Neutron diffraction as a tool to monitor the establishment of the electro-osmotic flux during realkalisation of carbonated concrete

NASA Astrophysics Data System (ADS)

Castellote, Marta; Llorente, I.; Andrade, Carmen; Turrillas, X.; Alonso, Cruz; Campo, Javier

2006-11-01

Realkalisation is an electrochemical technique for repairing concrete structures damaged by rebar corrosion due to carbonation. The treatment aims at restoring alkalinity of the concrete by application of a continuous current between the rebar, acting as a cathode, and an external auxiliary electrode placed in a carbonate solution and connected to a positive pole of a power supply. Here we report the application of neutron diffraction in the in situ monitoring of a realkalisation treatment, analysing at the same time the development of the electro-osmotic flux and the microstructural variations in the surroundings of the rebar.

Hemispherical cavities on silicon substrates: an overview of micro fabrication techniques

NASA Astrophysics Data System (ADS)

Poncelet, O.; Rasson, J.; Tuyaerts, R.; Coulombier, M.; Kotipalli, R.; Raskin, J.-P.; Francis, L. A.

2018-04-01

Hemispherical photonic crystals found in species like Papilio blumei and Cicendella chinensis have inspired new applications like anti-counterfeiting devices and gas sensors. In this work, we investigate and compare four different ways to micro fabricate such hemispherical cavities: using colloids as template, by wet (HNA) or dry (XeF2) isotropic etching of silicon and by electrochemical etching of silicon. The shape and the roughness of the obtained cavities have been discussed and the pros/cons for each method are highlighted.

Characterization of graphene oxide produced by Hummers method and its supercapacitor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akgül, Ö., E-mail: omeraakgul@gmail.com; Tanrıverdi, A., E-mail: aa.kudret@hotmail.com; Alver, Ü., E-mail: ualver@ktu.edu.tr

2016-03-25

In this study, Graphene Oxide (GO) is produced using Hummers method. The produced GO were investigated by x-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), UV-Vis spectrum, Raman spectroscopy and scanning electron microscopy (SEM). GO films on Ni foam were prepared by doctor-blading technique. The electrochemical performances of the as-synthesized GO electrode was evaluated using cyclic voltammetry (CV) in 6 M KOH aqueous solution. Capacitances of GO electrode was measured as 0.76 F/g.

Investigating effectiveness of activated carbons of natural sources on various supercapacitors

NASA Astrophysics Data System (ADS)

Faisal, Md. Shahnewaz Sabit; Rahman, Muhammad M.; Asmatulu, Ramazan

2016-04-01

Activated carbon can be produced from natural sources, such as pistachio and acorn shells, which can be an inexpensive and sustainable sources of natural wastes for the energy storage devices, such as supercapacitors. The carbonaceous materials used in this study were carbonized at the temperatures of 700°C and 900°C after the stabilization process at 240°C for two hours. These shells showed approximately 60% carbon yield. Carbonized nutshells were chemically activated using1wt% potassium hydroxide (KOH). Activated carbon powders with polyvinylidene fluoride (PVdF) were used to construct carbon electrodes. A 1M of tetraethylammonium tetrafluoroborate (TEABF4) and propylene carbonate (PC) were used as electrolytes. Electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for the characterization of the supercapacitors. Scanning electron microscopy (SEM) was used to inspect the surface texture of the activated carbons. Activated pistachio shells carbonized at 700°C showed more porous surface texture than those carbonized at 900°C. Effects of the carbonization temperatures were studied for their electrochemical characteristics. The shells carbonized at 700°C showed better electrochemical characteristics compared to those carbonized at 900°C. The test results provided about 27,083 μF/g specific capacitance at a scan rate of 10mV/s. This study showed promising results for using these activated carbons produced from the natural wastes for supercapacitor applications.

ZnO nanoparticles via Moringa oleifera green synthesis: Physical properties & mechanism of formation

NASA Astrophysics Data System (ADS)

Matinise, N.; Fuku, X. G.; Kaviyarasu, K.; Mayedwa, N.; Maaza, M.

2017-06-01

The research work involves the development of better and reliable method for the bio-fabrication of Zinc oxide nanoparticles through green method using Moringa Oleifera extract as an effective chelating agent. The electrochemical activity, crystalline structure, morphology, isothermal behavior, chemical composition and optical properties of ZnO nanoparticles were studied using various characterization techniques i.e. Cyclic voltammetry (CV), X-ray powder diffraction (XRD), High resolution transmission electron microscopy (HRTEM), Selected area electron diffraction (SEAD), Differential scanning calorimetry/thermogravimetric analysis (DSC/TGA), Fourier Transform Infrared analysis (FTIR) and Ultraviolet spectroscopy studies (UV-vis). The electrochemical analysis proved that the ZnO nano has high electrochemical activity without any modifications and therefore are considered as a potential candidate in electrochemical applications. The XRD pattern confirmed the crystallinity and pure phase of the sample. DSC/TGA analysis of ZnO sample (before anneal) revealed three endothermic peaks around 140.8 °C, 223.7 °C and 389.5 °C. These endothermic peaks are attributed to the loss of volatile surfactant, conversion of zinc hydroxide to zinc oxide nanoparticles and transformation of zinc oxide into zinc nanoparticles. Mechanisms of formation of the ZnO nanoparticles via the chemical reaction of the Zinc nitrate precursor with the bioactive compounds of the Moringa oleifera are proposed for each of the major family compounds: Vitamins, Flavonoids, and Phenolic acids.

Analysis of Protein-Phenolic Compound Modifications Using Electrochemistry Coupled to Mass Spectrometry.

PubMed

Kallinich, Constanze; Schefer, Simone; Rohn, Sascha

2018-01-29

In the last decade, electrochemical oxidation coupled with mass spectrometry has been successfully used for the analysis of metabolic studies. The application focused in this study was to investigate the redox potential of different phenolic compounds such as the very prominent chlorogenic acid. Further, EC/ESI-MS was used as preparation technique for analyzing adduct formation between electrochemically oxidized phenolic compounds and food proteins, e.g., alpha-lactalbumin or peptides derived from a tryptic digestion. In the first step of this approach, two reactant solutions are combined and mixed: one contains the solution of the digested protein, and the other contains the phenolic compound of interest, which was, prior to the mixing process, electrochemically transformed to several oxidation products using a boron-doped diamond working electrode. As a result, a Michael-type addition led to covalent binding of the activated phenolic compounds to reactive protein/peptide side chains. In a follow-up approach, the reaction mix was further separated chromatographically and finally detected using ESI-HRMS. Compound-specific, electrochemical oxidation of phenolic acids was performed successfully, and various oxidation and reaction products with proteins/peptides were observed. Further optimization of the reaction (conditions) is required, as well as structural elucidation concerning the final adducts, which can be phenolic compound oligomers, but even more interestingly, quite complex mixtures of proteins and oxidation products.

Stretchable Electrochemical Sensor for Real-Time Monitoring of Cells and Tissues.

PubMed

Liu, Yan-Ling; Jin, Zi-He; Liu, Yan-Hong; Hu, Xue-Bo; Qin, Yu; Xu, Jia-Quan; Fan, Cui-Fang; Huang, Wei-Hua

2016-03-24

Stretchable electrochemical sensors are conceivably a powerful technique that provides important chemical information to unravel elastic and curvilinear living body. However, no breakthrough was made in stretchable electrochemical device for biological detection. Herein, we synthesized Au nanotubes (NTs) with large aspect ratio to construct an effective stretchable electrochemical sensor. Interlacing network of Au NTs endows the sensor with desirable stability against mechanical deformation, and Au nanostructure provides excellent electrochemical performance and biocompatibility. This allows for the first time, real-time electrochemical monitoring of mechanically sensitive cells on the sensor both in their stretching-free and stretching states as well as sensing of the inner lining of blood vessels. The results demonstrate the great potential of this sensor in electrochemical detection of living body, opening a new window for stretchable electrochemical sensor in biological exploration. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Review of Interface Electronic Systems for AT-cut Quartz Crystal Microbalance Applications in Liquids

PubMed Central

Arnau, Antonio

2008-01-01

From the first applications of AT-cut quartz crystals as sensors in solutions more than 20 years ago, the so-called quartz crystal microbalance (QCM) sensor is becoming into a good alternative analytical method in a great deal of applications such as biosensors, analysis of biomolecular interactions, study of bacterial adhesion at specific interfaces, pathogen and microorganism detection, study of polymer film-biomolecule or cell-substrate interactions, immunosensors and an extensive use in fluids and polymer characterization and electrochemical applications among others. The appropriate evaluation of this analytical method requires recognizing the different steps involved and to be conscious of their importance and limitations. The first step involved in a QCM system is the accurate and appropriate characterization of the sensor in relation to the specific application. The use of the piezoelectric sensor in contact with solutions strongly affects its behavior and appropriate electronic interfaces must be used for an adequate sensor characterization. Systems based on different principles and techniques have been implemented during the last 25 years. The interface selection for the specific application is important and its limitations must be known to be conscious of its suitability, and for avoiding the possible error propagation in the interpretation of results. This article presents a comprehensive overview of the different techniques used for AT-cut quartz crystal microbalance in in-solution applications, which are based on the following principles: network or impedance analyzers, decay methods, oscillators and lock-in techniques. The electronic interfaces based on oscillators and phase-locked techniques are treated in detail, with the description of different configurations, since these techniques are the most used in applications for detection of analytes in solutions, and in those where a fast sensor response is necessary. PMID:27879713

A novel electrochemical biosensor based on polyadenine modified aptamer for label-free and ultrasensitive detection of human breast cancer cells.

PubMed

Wang, Kun; He, Meng-Qi; Zhai, Fu-Heng; He, Rong-Huan; Yu, Yong-Liang

2017-05-01

Simple, rapid, sensitive, and specific detection of cancer cells plays a pivotal role in the diagnosis and prognosis of cancer. A sandwich electrochemical biosensor was developed based on polyadenine (polydA)-aptamer modified gold electrode (GE) and polydA-aptamer functionalized gold nanoparticles/graphene oxide (AuNPs/GO) hybrid for the label-free and selective detection of breast cancer cells (MCF-7) via a differential pulse voltammetry (DPV) technique. Due to the intrinsic affinity between multiple consecutive adenines of polydA sequences and gold, polydA modified aptamer instead of thiol terminated aptamer was immobilized on the surface of GE and AuNPs/GO. The label-free MCF-7 cells could be recognized by polydA-aptamer and self-assembled onto the surface of GE. The polydA-aptamer functionalized AuNPs/GO hybrid could further bind to MCF-7 cells to form a sandwich sensing system. Characterization of the surface modified GE was carried out by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using Fe(CN) 6 3-/4- as a redox probe. Under the optimized experimental conditions, a detection limit of 8 cellsmL -1 (3σ/slope) was obtained for MCF-7 cells by the present electrochemical biosensor, along with a linear range of 10-10 5 cellsmL -1 . By virtue of excellent sensitivity, specificity and repeatability, the present electrochemical biosensor provides a potential application in point-of-care cancer diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Space Electrochemical Research and Technology. Abstracts

NASA Technical Reports Server (NTRS)

1995-01-01

This document contains abstracts of the proceedings of NASA's fifth Space Electrochemical Research and Technology (SERT) Conference, held at the NASA Lewis Research Center on May 1-3, 1995. The objective of the conference was to assess the present status and general thrust of research and development in those areas of electrochemical technology required to enable NASA missions into the next century. The conference provided a forum for the exchange of ideas and opinions of those actively involved in the field, in order to define new opportunities for the application of electrochemical processes in future NASA missions. Papers were presented in three technical areas: (1) the electrochemical interface, (2) the next generation in aerospace batteries and fuel cells, and (3) electrochemistry for non-energy storage applications. This document contains the abstracts of the papers presented.

Fundamentals of electrochemical detection techniques for CE and MCE.

PubMed

Kubán, Pavel; Hauser, Peter C

2009-10-01

The electroanalytical techniques of amperometry, conductometry and potentiometry match well with the instrumental simplicity of CE. Indeed, all three detection approaches have been reported for electrophoretic separations. However, the characteristics of the three methods are quite distinct and these are not related to the optical methods more commonly employed. A detailed discussion of the underlying principles of each is given. The issue of possible effects of the separation voltage on the electrochemical detection techniques is considered in depth, and approaches to the elimination of such interferences are also discussed for each case.

Electrochemical immunoassay for tumor markers based on hydrogels.

PubMed

Yin, Shuang; Ma, Zhanfang

2018-05-08

Hydrogel-based electrochemical immunoassays exhibit a large surface-to-volume ratio, excellent biocompatibility, unique stimuli-responsive behavior, high permeability and hydrophilicity and, thus, have shown great potential in the sensitive and accurate detection of tumor markers. Electrochemical immunosensing techniques for tumor markers based on hydrogels have greatly progressed in recent years. Areas covered: In this review, the authors describe the recent advances of hydrogel-based electrochemical immunosensing interface of tumor markers based on the different functions of hydrogels including conductive, catalytic, redox, stimuli-responsive and antifouling hydrogels. Expert commentary: Hydrogels have been successfully employed in electrochemical immunoassay of tumor markers, which is accountable to their unique properties. For further exploitation of hydrogel-based electrochemical biosensors, more variety of hydrogels need be fabricated with improved functionality.

Electrochemical Synthesis of Graphene/MnO2 Nano-Composite for Application to Supercapacitor Electrode.

PubMed

Jeong, Kwang Ho; Lee, Hyeon Jeong; Simpson, Michael F; Jeong, Mun

2016-05-01

Graphene/MnO2 nano-composite was electrochemically synthesized for application to an electrode material for electrochemical supercapacitors. The nanosized needle-like MnO2 was obtained by use of a graphene substrate. The prepared composite exhibited an ideal supercapacitive behavior. A capacitance retention of 94% was achieved with a 4 h deposition time (an initial capacitance of 574 mF/cm2 at a scan rate of 20 mV/s) and the retention declined with further deposition time. The results demonstrate enhanced contact between the electrode and electrolyte and improved power density as an electrochemical capacitor.

Vertically aligned nanowires from boron-doped diamond.

PubMed

Yang, Nianjun; Uetsuka, Hiroshi; Osawa, Eiji; Nebel, Christoph E

2008-11-01

Vertically aligned diamond nanowires with controlled geometrical properties like length and distance between wires were fabricated by use of nanodiamond particles as a hard mask and by use of reactive ion etching. The surface structure, electronic properties, and electrochemical functionalization of diamond nanowires were characterized by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) as well as electrochemical techniques. AFM and STM experiments show that diamond nanowire etched for 10 s have wire-typed structures with 3-10 nm in length and with typically 11 nm spacing in between. The electrode active area of diamond nanowires is enhanced by a factor of 2. The functionalization of nanowire tips with nitrophenyl molecules is characterized by STM on clean and on nitrophenyl molecule-modified diamond nanowires. Tip-modified diamond nanowires are promising with respect to biosensor applications where controlled biomolecule bonding is required to improve chemical stability and sensing significantly.

Composite polymer electrolyte based on PEO/Pvdf-HFP with MWCNT for lithium battery applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pradeepa, P.; Edwinraj, S.; Sowmya, G.

In the present study PEO and PVdF-HFP blend based composite polymer electrolytes (CPEs) has been prepared by using Multi Walled Carbon Nanotube (MWCNT), in order to examine the filler addition effect on the electrochemical properties. The complexed nanocomposite polymer electrolytes were obtained in the form of dimensionally stable and free standing films by using solution casting technique. The electrochemical properties of CPEs were measured by the AC impedance method. From the ionic conductivity results, the CPE containing MWCNT 2wt% showed the highest ionic conductivity with an excellent thermal stability at room temperature. The dielectric loss curve s for the samplemore » 6.25wt% PEO: 18.75 wt% PVdF-HFP: 2wt% MWCNT reveal the low frequency β relaxation peak pronounced at high temperature, and it may caused by side group dipoles.« less

Electrochemical and spectroelectrochemical study on novel non-peripherally tetra 1,2,4-triazole substituted phthalocyanines

NASA Astrophysics Data System (ADS)

Demirbaş, Ümit; Akyüz, Duygu; Akçay, Hakkı Türker; Koca, Atıf; Bekircan, Olcay; Kantekin, Halit

2018-03-01

In the present study novel tetra 4-(4-fluorophenyl)-5-(4-methoxyphenyl)-4H-1,2,4-triazole-3-thio substituted non-peripherally metal free (4), zinc(II) (5), lead (II) (6) and copper(II) (7) phthalocyanines were synthesized. The obtained novel compounds were characterized by a combination of FT-IR, 1H NMR, UV-Vis and MALDI-TOF techniques. The redox properties of the complexes have been investigated via cyclic voltammetry, square wave voltammetry and in situ spectroelectrochemistry. The compounds displayed ring-based, reversible and/or quasi-reversible reduction and oxidation processes and aggregation of the complexes influenced the redox character of the processes. The color changes during the redox processes of metallo phthalocyanine were recorded by in-situ spectroelectrochemical measurements. In situ UV-vis spectroelectrochemical measurements, which was associated with color change of the complexes, showed their applicability in the fields of the electrochemical technologies.

Operando characterization of batteries using x-ray absorption spectroscopy: advances at the beamline XAFS at synchrotron Elettra

NASA Astrophysics Data System (ADS)

Aquilanti, Giuliana; Giorgetti, Marco; Dominko, Robert; Stievano, Lorenzo; Arčon, Iztok; Novello, Nicola; Olivi, Luca

2017-02-01

X-ray absorption spectroscopy is a synchrotron radiation based technique that is able to provide information on both local structure and electronic properties in a chemically selective manner. It can be used to characterize the dynamic processes that govern the electrochemical energy storage in batteries, and to shed light on the redox chemistry and changes in structure during galvanostatic cycling to design cathode materials with improved properties. Operando XAS studies have been performed at beamline XAFS at Elettra on different systems. For Li-ion batteries, a multiedge approach revealed the role of the different cathode components during the charge and discharge of the battery. In addition, Li-S batteries for automotive applications were studied. Operando sulfur K-edge XANES and EXAFS analysis was used to characterize the redox chemistry of sulfur, and to relate the electrochemical mechanism to its local structure.

In Situ NMR Observation of the Temporal Speciation of Lithium Sulfur Batteries during Electrochemical Cycling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hao; Sa, Niya; He, Meinan

The understanding of the reaction mechanism and temporal speciation of the lithium sulfur batteries is challenged by complex polysulfide disproportionation chemistry coupled with the precipitation and dissolution of species. In this report, for the first time, we present a comprehensive method to investigate lithium sulfur electrochemistry using in situ 7Li NMR spectroscopy, a technique that is capable of quantitatively capturing the evolution of the soluble and precipitated lithium (poly)sulfides during electrochemical cycling. Furthermore, through deconvolution and quantification, every lithium-bearing species was closely tracked and four-step soluble lithium polysulfide-mediated lithium sulfur electrochemistry was demonstrated in never before seen detail. Significant irreversiblemore » accumulation of Li 2S is observed on the Li metal anode after four cycles because of sulfur shuttling. We present the application of the method in order to study electrolyte/additive development and lithium protection research can be readily envisaged.« less

In Situ NMR Observation of the Temporal Speciation of Lithium Sulfur Batteries during Electrochemical Cycling

DOE PAGES

Wang, Hao; Sa, Niya; He, Meinan; ...

2017-03-03

The understanding of the reaction mechanism and temporal speciation of the lithium sulfur batteries is challenged by complex polysulfide disproportionation chemistry coupled with the precipitation and dissolution of species. In this report, for the first time, we present a comprehensive method to investigate lithium sulfur electrochemistry using in situ 7Li NMR spectroscopy, a technique that is capable of quantitatively capturing the evolution of the soluble and precipitated lithium (poly)sulfides during electrochemical cycling. Furthermore, through deconvolution and quantification, every lithium-bearing species was closely tracked and four-step soluble lithium polysulfide-mediated lithium sulfur electrochemistry was demonstrated in never before seen detail. Significant irreversiblemore » accumulation of Li 2S is observed on the Li metal anode after four cycles because of sulfur shuttling. We present the application of the method in order to study electrolyte/additive development and lithium protection research can be readily envisaged.« less

Epoxy Chip-in-Carrier Integration and Screen-Printed Metalization for Multichannel Microfluidic Lab-on-CMOS Microsystems.

PubMed

Li, Lin; Yin, Heyu; Mason, Andrew J

2018-04-01

The integration of biosensors, microfluidics, and CMOS instrumentation provides a compact lab-on-CMOS microsystem well suited for high throughput measurement. This paper describes a new epoxy chip-in-carrier integration process and two planar metalization techniques for lab-on-CMOS that enable on-CMOS electrochemical measurement with multichannel microfluidics. Several design approaches with different fabrication steps and materials were experimentally analyzed to identify an ideal process that can achieve desired capability with high yield and low material and tool cost. On-chip electrochemical measurements of the integrated assembly were performed to verify the functionality of the chip-in-carrier packaging and its capability for microfluidic integration. The newly developed CMOS-compatible epoxy chip-in-carrier process paves the way for full implementation of many lab-on-CMOS applications with CMOS ICs as core electronic instruments.

Morphology, Composition, and Bioactivity of Strontium-Doped Brushite Coatings Deposited on Titanium Implants via Electrochemical Deposition

PubMed Central

Liang, Yongqiang; Li, Haoyan; Xu, Jiang; Li, Xin; Qi, Mengchun; Hu, Min

2014-01-01

Surface modification techniques have been applied to generate titanium implant surfaces that promote osseointegration for use in dental applications. In this study, strontium-doped brushite coatings were deposited on titanium by electrochemical deposition. The phase composition of the coating was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. The surface morphologies of the coatings were studied through scanning electron microscopy, and the cytocompatibility and bioactivity of the strontium-doped brushite coatings were evaluated using cultured osteoblasts. Osteoblast proliferation was enhanced by the addition of strontium, suggesting a possible mechanism by which strontium incorporation in brushite coatings increased bone formation surrounding the implants. Cell growth was also strongly influenced by the composition of the deposited coatings, with a 10% Sr-doped brushite coating inducing the greatest amount of bone formation among the tested materials. PMID:24901526

Carbon materials modified by plasma treatment as electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Lota, Grzegorz; Tyczkowski, Jacek; Kapica, Ryszard; Lota, Katarzyna; Frackowiak, Elzbieta

The carbon material was modified by RF plasma with various reactive gases: O 2, Ar and CO 2. Physicochemical properties of the final carbon products were characterized using different techniques such as gas adsorption method and XPS. Plasma modified materials enriched in oxygen functionalities were investigated as electrodes for supercapacitors in acidic medium. The electrochemical measurements have been carried out using cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy. The electrochemical measurements have confirmed that capacity characteristics are closely connected with a type of plasma exposition. Modification processes have an influence on the kind and amount of surface functional groups in the carbon matrix. The moderate increase of capacity of carbon materials modified by plasma has been observed using symmetric two-electrode systems. Whereas investigations made in three-electrode system proved that the suitable selection of plasma modification parameters allows to obtain promising negative and positive electrode materials for supercapacitor application.

PILOT SCALE REACTOR FOR ELECTROCHEMICAL DECHLORINATION OF MODEL CHLORINATED CONTAMINANTS

EPA Science Inventory

Electrochemical degradation (ECD) is a promising technology for in-situ remediation of diversely contaminated submarine matrices, by the application of low level DC electric fields. This study, prompted by successful bench-scale electrochemical dechlorination of Trichloroe...

Characterization of Copper Corrosion Products in Drinking Water by Combining Electrochemical and Surface Analyses

EPA Science Inventory

This study focuses on the application of electrochemical approaches to drinking water copper corrosion problems. Applying electrochemical approaches combined with copper solubility measurements, and solid surface analysis approaches were discussed. Tafel extrapolation and Electro...

Characterization of Copper Corrosion Products Formed in Drinking Water by Combining Electrochemical and Surface Analyses

EPA Science Inventory

This study focuses on the application of electrochemical approaches to drinking water copper corrosion problems. Applying electrochemical approaches combined with copper solubility measurements, and solid surface analysis approaches were discussed. Tafel extrapolation and Electro...

Electrochemistry at Nanometer-Scaled Electrodes

ERIC Educational Resources Information Center

Watkins, John J.; Bo Zhang; White, Henry S.

2005-01-01

Electrochemical studies using nanometer-scaled electrodes are leading to better insights into electrochemical kinetics, interfacial structure, and chemical analysis. Various methods of preparing electrodes of nanometer dimensions are discussed and a few examples of their behavior and applications in relatively simple electrochemical experiments…

Material Characterization in the Electro-Analytic Approach for Applications in Chemical Mechanical Planarization and Electrochemical Energy Systems

NASA Astrophysics Data System (ADS)

Rock, Simon E.

The work presented in this thesis covers electro-analytical characterization for multiple applications in material science. Electrochemical techniques were used to investigate soluble film formation on metals used in chemical mechanical planarization in order to better understand the removal rate process by studying new chemicals proposed by groups in industry. Second, an ionic liquid was used as an electrolyte in a lithium ion cathode half cell to show the essential functionality of the IL and the temperature advantage over traditional electrolytes. Lastly, a comprehensive measurement for charge recombination in dye-sensitized solar cells was performed using both open-circuit voltage decay and impedance spectroscopy, which may be used to better understand the limiting factors that affect the cell's efficiently. Electrochemical techniques were applied to new methods and materials to extend the development of material manufacturing and advance the measurement process. The fabrication of interconnect structures for semiconductor devices requires low down-pressure chemical mechanical planarization (CMP) of Ta barrier layers. Guanidine carbonate (GC) serves as an effective surface-complexing agent for such CMP applications, where the rate of Ta removal can be chemically controlled through pH-tuned selectivity with respect to the removal of Cu lines. Electrochemical techniques are employed in this work to study the surface-modifying roles of GC that make this chemical an attractive complexing agent for Ta CMP. In addition, the effects of including H2O2 (an oxidizer) and dodecyl benzene sulfonic acid (DBSA, a dissolution inhibitor for Cu) in GC-based CMP solutions are investigated to examine the selective CMP mechanisms of Ta and Cu in these solutions. The results suggest that the removal of Ta is supported in part by structurally weak guanidinium-tantalic-acid surface complexes formed on Ta/Ta2O5. The bicarbonate/carbonate anions of GC also facilitate Ta removal through the generation of ion-incorporated tantalum pentoxide. DBSA strongly affects the CMP chemistry of Cu, but exhibits relatively weaker effects on the surface activity of Ta, and thus plays a vital role in dictating the selectivity of Ta:Cu polish rates. CMP of tantalum nitride is also an essential step of material processing in the fabrication of integrated circuits, which is looked separately in this thesis. The present work investigates certain chemical aspects of this strategy of TaN-CMP by also using guanidine carbonate (GC) as a surface complexing agent, and employing electrochemical experiments. The experiments are designed to study the chemical and electrochemical origins of the CMP-specific surface complex films formed on a TaN wafer in acidic solutions of GC and hydrogen peroxide. Open circuit potential, polarization resistance, and electrochemical impedance measurements are employed to probe the surface effects that facilitate material removal in chemically prevailing CMP of TaN. The results are discussed in view of designing slurry variables to support barrier layer planarization with reduced roles of mechanical abrasion. Nonvolatile and nonflammable ionic liquids (ILs) have distinct thermal advantages over the traditional organic solvent electrolytes of lithium ion batteries. However, this beneficial feature of ILs is often counterbalanced by their high viscosity (a limiting factor for ionic conductivity) and, sometimes, by their unsuitable electrochemistry for generating protective layers on electrode surfaces. In an effort to alleviate these limiting Aspects of ILs, we have synthesized a PEGylated imidazolium bis(triflouromethylsulfonyl)amide (bistriflamide) IL that exhibited better thermal and electrochemical stability than a conventional electrolyte based on a blend of ethylene carbonate and diethyl carbonate. The electrochemical performance of this IL has been demonstrated using a cathode consisting of ball-milled LiMn2O4 particles. A direct comparison of the ionic liquid electrolyte with the nonionic low-viscosity conventional solvent blend is presented. Charge recombination at the electrolyte-photoanode interface of a dye sensitized solar cell (DSSC) is a major efficiency-limiting factor of the cell. To mitigate this recombination effect it is necessary to ensure that the effective electron lifetime in the DSSC is longer than the electron's transit time across the photoanode of mesoporous TiO2. While the efforts aimed at accomplishing this goal are often based on new materials/designs of photoanodes, a quantitative evaluation of these designs relies on the precision of the benchmarking measurements of electron lifetimes. The open circuit voltage decay (OCVD) technique offers an effective yet straightforward method for such measurements. The present work focuses on certain experimental criteria for ensuring the accuracy of these experiments, and probes the associated effects of temperature variations in the solar cell. The results demonstrate that, a high rate of data sampling is essential for adequately resolving the fast initial stages of charge recombination. The results also show the effects of nonlinear recombination where second order OCV variations are operative. The findings of the OCVD experiments are compared with a parallel set of tests carried out using impedance spectroscopy. The relative roles of the two sets of analytical measurements are examined.

Design and fabrication of nanoelectrodes for applications with scanning electrochemical microscopy

NASA Astrophysics Data System (ADS)

Thakar, Rahul

Scanning electrochemical microscope (SECM) was introduced two decades ago and has since emerged as a powerful research tool to investigate localized electrochemical reactions at the surface of material and biological samples. The ability to obtain chemical information at a surface differentiates SECM from competing scanning probe microscopy (SPM) techniques. Although, chemical specificity is a unique advantage offered by SECM, inherent limitations due to a slow feedback response, and challenges associated with production of smaller electrodes have remained major drawbacks. Initially in this research, SECM was utilized as a characterization and investigative tool. Later, advances in SECM imaging were achieved with design and production of multifunctional nanoelectrodes. At first, platinum based nanoelectrodes were fabricated for use as electrochemical probes to investigate local electron transfer at chemically-modified surfaces. Further, micron and sub-micron platinum electrodes with chemically modified shrouds were prepared and characterized with voltammetric measurements. Studies reveal experimental evidence for the presence of edge-effects that are typically associated with submicron electrodes. Interestingly, we observed selectivity of these electrodes based on hydrophobic/ hydrophilic character. Through vapor deposition of parylene over microstructured material, single-pore membranes and porous membrane arrays were produced. Pore size characterization within porous membranes was performed with templated growth of micro/nanostructures. Characterization of transport properties of ions and redox-active molecules through hydrophobic parylene membranes was investigated with ion conductance microscopy and SECM, individually. Parylene is an insulative material that is chemically resistant, deposits conformally over high-aspect ratio objects and also converts into conductive carbon at high-temperature pyrolysis. Motivated by these results we identified a unique strategy to fabricate parylene based carbon electrodes Here, we have developed a unique strategy to obtain carbon based nanoelectrodes from vapor deposition of parylene over pulled glass nanopipettes. With this approach, multiple electrode geometries were constructed and the application of individual geomtery with SECM is demonstrated. In particular, enhanced spatial resolution and electrochemical information were obtained with the use of carbon ring/nanopore electrodes. Practical implications of edge-effects observed with carbon ring/nanopore electrodes is discussed with substrate generation tip collection (SG/TC) SECM Carbon ring/nanopore electrodes have also enabled the use of SECM in conjunction with ion conductance microscopy to alleviate the issue of poor feedback response. This has further helped in deconvolution of electrochemcial and topographical signals. Although, use of carbon nanoelectrodes is discussed with specific applications to electrochemcial microscopy, these probes have wide utility in electroanalytical applications. Initial proof-of-concept experiments along with future directions for this work are presented.

Synthesis and characterization of Cu3Se2 nanofilms by an underpotential deposition based electrochemical codeposition technique

NASA Astrophysics Data System (ADS)

Aydın, Zehra Yazar; Abacı, Serdar

2017-12-01

The Cu3Se2 nanofilms were synthesized with underpotential deposition based electrochemical codeposition technique for the first time in the literature. The electrochemical behaviors of copper and selenium were investigated in 0.1 M H2SO4 on Au electrode. The effects of concentration and scan rate on the electrochemical behavior of selenium were studied. The electrochemical behaviors in underpotential deposition and bulk regions of the Cu-Se system were investigated in acidic solution by cyclic voltammetry and electrolysis techniques. X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and ultraviolet and visible absorption spectroscopy techniques were used for characterization of synthesized films. According to the X-ray photoelectron spectroscopy spectrum, Cu/Se ratio was determined to be approximately 3/2. Copper selenide nanofilms are two phases and polycrystalline according to X-ray diffraction. The films mainly formed tetragonal Cu3Se2 (umangite mineral structure) structure and the particle size was approximately 45.95 nm. Scanning electron microscopy images showed that Cu3Se2 nanofilms consisted of uniform, nano-sizes and two-dimensional. It was found through AFM that the surface roughness of the film was 6.173 nm, with a mean particle size of around 50 nm. Depending on the deposition time, the band gaps of the Cu3Se2 films were in the range of 2.86-3.20 eV. Three characteristic vibrational modes belonging to Cu3Se2 nanofilms were recorded in the Raman spectrum.

Aptamer-aided target capturing with biocatalytic metal deposition: an electrochemical platform for sensitive detection of cancer cells.

PubMed

Yi, Zi; Li, Xiao-Yan; Gao, Qing; Tang, Li-Juan; Chu, Xia

2013-04-07

A novel aptamer biosensor for cancer cell assay has been reported on the basis of ultrasensitive electrochemical detection. Cancer cell capturing is first accomplished via aptamer-aided recognition, and the cell-aptamer binding events then mediate an alkaline phosphatase-catalyzed silver deposition reaction which can be probed by electrochemical detection. Following biocatalytic silver deposition, an efficient amplification approach for sensitive electrochemical measurements is demonstrated, for cell detection with high sensitivity. Ramos cell are used as a model case, a typical biomarker of the acute blood cell cancer, Burkitt's lymphoma. The results reveal that the developed technique displays desirable selectivity in Ramos cell discrimination, and linear response range from 10 to 10(6) cells with a detection limit as low as 10 cells. Due to the simple procedures, label-free and electrochemistry based detection format, this technique is simple and cost-effective, and exhibits excellent compatibility with miniaturization technologies. The electrochemical cell detection strategy may create an intrinsically specific and sensitive platform for cancer cell assay and associated studies.

Investigation of the electrochemically active surface area and lithium diffusion in graphite anodes by a novel OsO4 staining method

NASA Astrophysics Data System (ADS)

Pfaffmann, Lukas; Birkenmaier, Claudia; Müller, Marcus; Bauer, Werner; Mitsch, Tim; Feinauer, Julian; Krämer, Yvonne; Scheiba, Frieder; Hintennach, Andreas; Schleid, Thomas; Schmidt, Volker; Ehrenberg, Helmut

2016-03-01

Negative electrodes of lithium-ion batteries generally consist of graphite-based active materials. In order to realize batteries with a high current density and therefore accelerated charging processes, the intercalation of lithium and the diffusion processes of these carbonaceous materials must be understood. In this paper, we visualized the electrochemical active surface area for three different anode materials using a novel OsO4 staining method in combination with scanning electron microscopy techniques. The diffusion behavior of these three anode materials is investigated by potentiostatic intermittent titration technique measurements. From those we determine the diffusion coefficient with and without consideration of the electrochemical active surface area.

Biocompatible enzymatic roller pens for direct writing of biocatalytic materials: "do-it-yourself" electrochemical biosensors.

PubMed

Bandodkar, Amay J; Jia, Wenzhao; Ramírez, Julian; Wang, Joseph

2015-06-03

The development of enzymatic-ink-based roller pens for direct drawing of biocatalytic sensors, in general, and for realizing renewable glucose sensor strips, in particular, is described. The resulting enzymatic-ink pen allows facile fabrication of high-quality inexpensive electrochemical biosensors of any design by the user on a wide variety of surfaces having complex textures with minimal user training. Unlike prefabricated sensors, this approach empowers the end user with the ability of "on-demand" and "on-site" designing and fabricating of biocatalytic sensors to suit their specific requirement. The resulting devices are thus referred to as "do-it-yourself" sensors. The bio-active pens produce highly reproducible biocatalytic traces with minimal edge roughness. The composition of the new enzymatic inks has been optimized for ensuring good biocatalytic activity, electrical conductivity, biocompati-bility, reproducible writing, and surface adherence. The resulting inks are characterized using spectroscopic, viscometric, electrochemical, thermal and microscopic techniques. Applicability to renewable blood glucose testing, epidermal glucose monitoring, and on-leaf phenol detection are demonstrated in connection to glucose oxidase and tyrosinase-based carbon inks. The "do-it-yourself" renewable glucose sensor strips offer a "fresh," reproducible, low-cost biocatalytic sensor surface for each blood test. The ability to directly draw biocatalytic conducting traces even on unconventional surfaces opens up new avenues in various sensing applications in low-resource settings and holds great promise for diverse healthcare, environmental, and defense domains. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Real time and in vivo monitoring of nitric oxide by electrochemical sensors--from dream to reality.

PubMed

Zhang, Xueji

2004-09-01

Nitric oxide is a key intercellular messenger in the human and animal bodies. The identification of nitric oxide (NO) as the endothelium-derived relaxing factor (EDRF) has driven an enormous effort to further elucidate the chemistry, biology and therapeutic actions of this important molecule. It has found that nitric oxide is involved in many disease states such as such as chronic heart failure, stroke, impotent (erectile dysfunction). The bioactivity of nitric oxide intrinsically linked to its diffusion from its site production to the sites of action. Accurate reliable in real time detection of NO in various biological systems is therefore crucial to understanding its biological role. However, the instability of NO in aqueous solution and its high reactivity with other molecules can cause difficulties for its measurement depending on the detection method employed. Although a variety of methods have been described to measure NO in aqueous environments, it is now generally accepted that electrochemical (amperometric) detection using NO-specific electrodes is the most reliable and sensitive technique available for real-time in situ detection of NO. In 1992 the first commercial NO electrode-based amperometric detection system was developed by WPI. The system has been used successfully for a number of years in a wide range of research applications, both in vitro and in vivo. Recently, many new electrochemical nitric sensors have been invented and commercialized. Here we describe some of the background principles in NO sensors design, methodology and their applications.

Signal-on electrochemical detection of antibiotics at zeptomole level based on target-aptamer binding triggered multiple recycling amplification.

PubMed

Wang, Hongzhi; Wang, Yu; Liu, Su; Yu, Jinghua; Guo, Yuna; Xu, Ying; Huang, Jiadong

2016-06-15

In the work, a signal-on electrochemical DNA sensor based on multiple amplification for ultrasensitive detection of antibiotics has been reported. In the presence of target, the ingeniously designed hairpin probe (HP1) is opened and the polymerase-assisted target recycling amplification is triggered, resulting in autonomous generation of secondary target. It is worth noting that the produced secondary target could not only hybridize with other HP1, but also displace the Helper from the electrode. Consequently, methylene blue labeled HP2 forms a "close" probe structure, and the increase of signal is monitored. The increasing current provides an ultrasensitive electrochemical detection for antibiotics down to 1.3 fM. To our best knowledge, such work is the first report about multiple recycling amplification combing with signal-on sensing strategy, which has been utilized for quantitative determination of antibiotics. It would be further used as a general strategy associated with more analytical techniques toward the detection of a wide spectrum of analytes. Thus, it holds great potential for the development of ultrasensitive biosensing platform for the applications in bioanalysis, disease diagnostics, and clinical biomedicine. Copyright © 2016 Elsevier B.V. All rights reserved.

Sputtered Pd as Hydrogen Storage for a Chip-Integrated Microenergy System

PubMed Central

Slavcheva, E.; Ganske, G.; Schnakenberg, U.

2014-01-01

The work presents a research on preparation and physical and electrochemical characterisation of dc magnetron sputtered Pd films envisaged for application as hydrogen storage in a chip-integrated hydrogen microenergy system. The influence of the changes in the sputtering pressure on the surface structure, morphology, and roughness was analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AMF). The electrochemical activity towards hydrogen adsorption/desorption and formation of PdH were investigated in 0.5 M H2SO4 using the methods of cyclic voltammetry and galvanostatic polarisation. The changes in the electrical properties of the films as a function of the sputtering pressure and the level of hydrogenation were evaluated before and immediately after the electrochemical charging tests, using a four-probe technique. The research resulted in establishment of optimal sputter regime, ensuring fully reproducible Pd layers with highly developed surface, moderate porosity, and mechanical stability. Selected samples were integrated as hydrogen storage in a newly developed unitized microenergy system and tested in charging (water electrolysis) and discharging (fuel cell) operative mode at ambient conditions demonstrating a stable recycling performance. PMID:24516356

The role of nanomaterials in redox-based supercapacitors for next generation energy storage devices.

PubMed

Zhao, Xin; Sánchez, Beatriz Mendoza; Dobson, Peter J; Grant, Patrick S

2011-03-01

The development of more efficient electrical storage is a pressing requirement to meet future societal and environmental needs. This demand for more sustainable, efficient energy storage has provoked a renewed scientific and commercial interest in advanced capacitor designs in which the suite of experimental techniques and ideas that comprise nanotechnology are playing a critical role. Capacitors can be charged and discharged quickly and are one of the primary building blocks of many types of electrical circuit, from microprocessors to large-sale power supplies, but usually have relatively low energy storage capability when compared with batteries. The application of nanostructured materials with bespoke morphologies and properties to electrochemical supercapacitors is being intensively studied in order to provide enhanced energy density without comprising their inherent high power density and excellent cyclability. In particular, electrode materials that exploit physical adsorption or redox reactions of electrolyte ions are foreseen to bridge the performance disparity between batteries with high energy density and capacitors with high power density. In this review, we present some of the novel nanomaterial systems applied for electrochemical supercapacitors and show how material morphology, chemistry and physical properties are being tailored to provide enhanced electrochemical supercapacitor performance.

Electrochemical MIP-Sensors for Drugs.

PubMed

Yarman, Aysu; Kurbanoglu, Sevinc; Jetzschmann, Katharina J; Ozkan, Sibel A; Wollenberger, Ulla; Scheller, Frieder

2017-10-05

In order to replace bio-macromolecules by stable synthetic materials in separation techniques and bioanalysis biomimetic receptors and catalysts have been developed: Functional monomers are polymerized together with the target analyte and after template removal cavities are formed in the "molecularly imprinted polymer" (MIP) which resemble the active sites of antibodies and enzymes. Staring almost 80 years ago, around 1,100 papers on MIPs were published in 2016. Electropolymerization allows to deposit MIPs directly on voltammetric electrodes or chips for quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). For the readout of MIPs for drugs amperometry, differential pulse voltammetry (DPV) and impedance spectroscopy (EIS) offer higher sensitivity as compared with QCM or SPR. Application of simple electrochemical devices allows both the reproducible preparation of MIP sensors, but also the sensitive signal generation. Electrochemical MIP-sensors for the whole arsenal of drugs, e.g. the most frequently used analgesics, antibiotics and anticancer drugs have been presented in literature and tested under laboratory conditions. These biomimetic sensors typically have measuring ranges covering the lower nano- up to millimolar concentration range and they are stable under extreme pH and in organic solvents like non-aqueous extracts. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Electrochemical attosyringe.

PubMed

Laforge, François O; Carpino, James; Rotenberg, Susan A; Mirkin, Michael V

2007-07-17

The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10(-18) to 10(-12) liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems.

Electrochemical attosyringe

PubMed Central

Laforge, François O.; Carpino, James; Rotenberg, Susan A.; Mirkin, Michael V.

2007-01-01

The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10−18 to 10−12 liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems. PMID:17620612

Electrochemical properties of TiO2-V2O5 nanocomposites as a high performance supercapacitors electrode material

NASA Astrophysics Data System (ADS)

Ray, Apurba; Roy, Atanu; Sadhukhan, Priyabrata; Chowdhury, Sreya Roy; Maji, Prasenjit; Bhattachrya, Swapan Kumar; Das, Sachindranath

2018-06-01

The individual components being ample, inexpensive and non-toxic material, TiO2-V2O5 has drawn more attention compared to other metal oxides. The cost-effective, non-toxic TiO2-V2O5 nanocomposites with various molar ratios of Ti and V have been synthesized through wet chemical method. Microstructure studies have been performed using X-ray diffraction (XRD), FESEM, HRTTEM and other spectroscopic (XPS, FTIR) techniques. The synthesized TiO2-V2O5 nanocomposite with molar ratio 10:20 exhibits 3D, mesoporous interlinked tube-like structure with excellent electrochemical properties by delivering highest specific capacitance of 310 F g-1 at 2 mV s-1 scan rate compared to individual TiO2 and V2O5 material. Increase in vanadium ratio plays a leading role to the chemical properties. The synergistic effects between TiO2 and V2O5 have also been observed in this work. Due to the excellent electrochemical as well as other acceptable performance, the porous interconnected tube like nanocomposite can be used for energy storage application mainly for pseudocapacitor electrode material.

High-quality metal oxide core/shell nanowire arrays on conductive substrates for electrochemical energy storage.

PubMed

Xia, Xinhui; Tu, Jiangping; Zhang, Yongqi; Wang, Xiuli; Gu, Changdong; Zhao, Xin-Bing; Fan, Hong Jin

2012-06-26

The high performance of a pseudocapacitor electrode relies largely on a scrupulous design of nanoarchitectures and smart hybridization of bespoke active materials. We present a powerful two-step solution-based method for the fabrication of transition metal oxide core/shell nanostructure arrays on various conductive substrates. Demonstrated examples include Co(3)O(4) or ZnO nanowire core and NiO nanoflake shells with a hierarchical and porous morphology. The "oriented attachment" and "self-assembly" crystal growth mechanisms are proposed to explain the formation of the NiO nanoflake shell. Supercapacitor electrodes based on the Co(3)O(4)/NiO nanowire arrays on 3D macroporous nickel foam are thoroughly characterized. The electrodes exhibit a high specific capacitance of 853 F/g at 2 A/g after 6000 cycles and an excellent cycling stability, owing to the unique porous core/shell nanowire array architecture, and a rational combination of two electrochemically active materials. Our growth approach offers a new technique for the design and synthesis of transition metal oxide or hydroxide hierarchical nanoarrays that are promising for electrochemical energy storage, catalysis, and gas sensing applications.

Investigation of molybdenum-crosslinker interfaces for affinity based electrochemical biosensing applications

NASA Astrophysics Data System (ADS)

Kamakoti, Vikramshankar; Shanmugam, Nandhinee Radha; Tanak, Ambalika Sanjeev; Jagannath, Badrinath; Prasad, Shalini

2018-04-01

Molybdenum (Mo) has been investigated for implementation as an electrode material for affinity based biosensing towards devloping flexibe electronic biosensors. Treatment of the native oxide of molybdenum was investigated through two surface treatment strategies namely thiol and carbodiimide crosslinking methods. The binding interaction between cross-linker molecules and Mo electrode surface has been characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and optical microscopy. The efficacy of treatment of Mo with its native oxide using carbodiimide cross linking methodology was established. The carbodiimide cross-linking chemistry was found to possess better surface coverage and binding affinity with Molybdenum electrode surface when compared to thiol cross-linking chemistry.Electrochemical characterization of Mo electrode using Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltametry (CV) techniques was performed to evaluate the effect of ionic properties of solution buffer on the Mo electrode's performance. Affinity based biosensing of C-Reactive Protein (CRP) has been demonstrated on a flexible nanoporous polymeric substrate with detection threshold of 100 pg/ml in synthetic urine buffer medium. The biosensor has been evaluated to be developed as a dipstick based point of care device for detection of biomarkers in urine.

The role of nanomaterials in redox-based supercapacitors for next generation energy storage devices

NASA Astrophysics Data System (ADS)

Zhao, Xin; Sánchez, Beatriz Mendoza; Dobson, Peter J.; Grant, Patrick S.

2011-03-01

The development of more efficient electrical storage is a pressing requirement to meet future societal and environmental needs. This demand for more sustainable, efficient energy storage has provoked a renewed scientific and commercial interest in advanced capacitor designs in which the suite of experimental techniques and ideas that comprise nanotechnology are playing a critical role. Capacitors can be charged and discharged quickly and are one of the primary building blocks of many types of electrical circuit, from microprocessors to large-sale power supplies, but usually have relatively low energy storage capability when compared with batteries. The application of nanostructured materials with bespoke morphologies and properties to electrochemical supercapacitors is being intensively studied in order to provide enhanced energy density without comprising their inherent high power density and excellent cyclability. In particular, electrode materials that exploit physical adsorption or redox reactions of electrolyte ions are foreseen to bridge the performance disparity between batteries with high energy density and capacitors with high power density. In this review, we present some of the novel nanomaterial systems applied for electrochemical supercapacitors and show how material morphology, chemistry and physical properties are being tailored to provide enhanced electrochemical supercapacitor performance.

In situ fabrication of electrochemically grown mesoporous metallic thin films by anodic dissolution in deep eutectic solvents.

PubMed

Renjith, Anu; Roy, Arun; Lakshminarayanan, V

2014-07-15

We describe here a simple electrodeposition process of forming thin films of noble metallic nanoparticles such as Au, Ag and Pd in deep eutectic solvents (DES). The method consists of anodic dissolution of the corresponding metal in DES followed by the deposition on the cathodic surface. The anodic dissolution process in DES overcomes the problems associated with copious hydrogen and oxygen evolution on the electrode surface when carried out in aqueous medium. The proposed method utilizes the inherent abilities of DES to act as a reducing medium while simultaneously stabilizing the nanoparticles that are formed. The mesoporous metal films were characterized by SEM, XRD and electrochemical techniques. Potential applications of these substrates in surface enhanced Raman spectroscopy and electrocatalysis have been investigated. A large enhancement of Raman signal of analyte was achieved on the mesoporous silver substrate after removing all the stabilizer molecules from the surface by calcination. The highly porous texture of the electrodeposited film provides superior electro catalytic performance for hydrogen evolution reaction (HER). The mechanisms of HER on the fabricated substrates were studied by Tafel analysis and electrochemical impedance spectroscopy (EIS). Copyright © 2014 Elsevier Inc. All rights reserved.

In situ cell culture monitoring on a Ti-6Al-4V surface by electrochemical techniques.

PubMed

García-Alonso, M C; Saldaña, L; Alonso, C; Barranco, V; Muñoz-Morris, M A; Escudero, M L

2009-05-01

In this work, the in situ interaction between Ti-6Al-4V alloy and osteoblastic cells has been studied by electrochemical techniques as a function of time. The interaction has been monitored for cell adhesion and growth of human osteoblastic Saos-2 cells on Ti-6Al-4V samples. The study has been carried out by electrochemical techniques, e.g., studying the evolution of corrosion potential with exposure time and by electrochemical impedance spectroscopy. The impedance results have been analyzed by using different equivalent circuit models that simulate the interface state at each testing time. The adhesion of the osteoblastic cells on the Ti-6Al-4V alloy leads to surface areas with different cell coverage rates, thus showing the different responses in the impedance diagrams with time. The effect of the cells on the electrochemical response of Ti-6Al-4V alloy is clearly seen after 4 days of testing, in which two isolated and well-differentiated time constants are clearly observed. One of these is associated with the presence of the cells and the other with a passive film on the Ti-6Al-4V alloy. After 7 days of culture, the system is governed by a resistive component over a wide frequency range which is associated with an increase in the cell coverage rate on the surface due to the extracellular matrix.

Synthesis and electrochemical performance of polyaniline @MnO2/graphene ternary composites for electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Pan, Chao; Gu, Haiteng; Dong, Li

2016-01-01

We introduce a facile method to construct new ternary hierarchical nanocomposites by combining MnO2 coated one dimensional (1D) conducting polyaniline (PANI) nanowires with 2D graphene sheets (GNs). The hierarchical nanocomposite structures of PANI@MnO2/GNs (PMGNs) are further proved by X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The electrochemical characteristics of the electrodes made of the hierarchical structured PMGNs materials are determined by the CV and galvanostatic measurements. These electrochemical tests indicate that electrodes made of the nanostructured PMGNs exhibit an improved reversible capacitance of 695 F g-1 after 1000 cycles at a high current density of 4 A g-1. The ternary composites possess higher electrochemical capacitance than each individual component as supercapacitor electrode materials. Such intriguing electrochemical performance is mainly attributed to the synergistic effects of MnO2, PANI and graphene. The hierarchical ternary nanocomposites show excellent electrochemical properties for energy storage applications, which evidence their potential application as supercapacitors.

Flexible and High Performance Supercapacitors Based on NiCo2O4for Wide Temperature Range Applications

NASA Astrophysics Data System (ADS)

Gupta, Ram K.; Candler, John; Palchoudhury, Soubantika; Ramasamy, Karthik; Gupta, Bipin Kumar

2015-10-01

Binder free nanostructured NiCo2O4 were grown using a facile hydrothermal technique. X-ray diffraction patterns confirmed the phase purity of NiCo2O4. The surface morphology and microstructure of the NiCo2O4 analyzed by scanning electron microscopy (SEM) showed flower-like morphology composed of needle-like structures. The potential application of binder free NiCo2O4 as an electrode for supercapacitor devices was investigated using electrochemical methods. The cyclic voltammograms of NiCo2O4 electrode using alkaline aqueous electrolytes showed the presence of redox peaks suggesting pseudocapacitance behavior. Quasi-solid state supercapacitor device fabricated by sandwiching two NiCo2O4 electrodes and separating them by ion transporting layer. The performance of the device was tested using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The device showed excellent flexibility and cyclic stability. The temperature dependent charge storage capacity was measured for their variable temperature applications. Specific capacitance of the device was enhanced by ~150% on raising the temperature from 20 to 60 °C. Hence, the results suggest that NiCo2O4 grown under these conditions could be a suitable material for high performance supercapacitor devices that can be operated at variable temperatures.

Flexible and High Performance Supercapacitors Based on NiCo2O4for Wide Temperature Range Applications.

PubMed

Gupta, Ram K; Candler, John; Palchoudhury, Soubantika; Ramasamy, Karthik; Gupta, Bipin Kumar

2015-10-20

Binder free nanostructured NiCo2O4 were grown using a facile hydrothermal technique. X-ray diffraction patterns confirmed the phase purity of NiCo2O4. The surface morphology and microstructure of the NiCo2O4 analyzed by scanning electron microscopy (SEM) showed flower-like morphology composed of needle-like structures. The potential application of binder free NiCo2O4 as an electrode for supercapacitor devices was investigated using electrochemical methods. The cyclic voltammograms of NiCo2O4 electrode using alkaline aqueous electrolytes showed the presence of redox peaks suggesting pseudocapacitance behavior. Quasi-solid state supercapacitor device fabricated by sandwiching two NiCo2O4 electrodes and separating them by ion transporting layer. The performance of the device was tested using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The device showed excellent flexibility and cyclic stability. The temperature dependent charge storage capacity was measured for their variable temperature applications. Specific capacitance of the device was enhanced by ~150% on raising the temperature from 20 to 60 °C. Hence, the results suggest that NiCo2O4 grown under these conditions could be a suitable material for high performance supercapacitor devices that can be operated at variable temperatures.

Flexible and High Performance Supercapacitors Based on NiCo2O4for Wide Temperature Range Applications

PubMed Central

Gupta, Ram K.; Candler, John; Palchoudhury, Soubantika; Ramasamy, Karthik; Gupta, Bipin Kumar

2015-01-01

Binder free nanostructured NiCo2O4 were grown using a facile hydrothermal technique. X-ray diffraction patterns confirmed the phase purity of NiCo2O4. The surface morphology and microstructure of the NiCo2O4 analyzed by scanning electron microscopy (SEM) showed flower-like morphology composed of needle-like structures. The potential application of binder free NiCo2O4 as an electrode for supercapacitor devices was investigated using electrochemical methods. The cyclic voltammograms of NiCo2O4 electrode using alkaline aqueous electrolytes showed the presence of redox peaks suggesting pseudocapacitance behavior. Quasi-solid state supercapacitor device fabricated by sandwiching two NiCo2O4 electrodes and separating them by ion transporting layer. The performance of the device was tested using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The device showed excellent flexibility and cyclic stability. The temperature dependent charge storage capacity was measured for their variable temperature applications. Specific capacitance of the device was enhanced by ~150% on raising the temperature from 20 to 60 °C. Hence, the results suggest that NiCo2O4 grown under these conditions could be a suitable material for high performance supercapacitor devices that can be operated at variable temperatures. PMID:26482921

Surface modification of a biodegradable magnesium alloy with phosphorylcholine (PC) and sulfobetaine (SB) functional macromolecules for reduced thrombogenicity and acute corrosion resistance.

PubMed

Ye, Sang-Ho; Jang, Yong-Seok; Yun, Yeo-Heung; Shankarraman, Venkat; Woolley, Joshua R; Hong, Yi; Gamble, Lara J; Ishihara, Kazuhiko; Wagner, William R

2013-07-02

Siloxane functionalized phosphorylcholine (PC) or sulfobetaine (SB) macromolecules (PCSSi or SBSSi) were synthesized to act as surface modifying agents for degradable metallic surfaces to improve acute blood compatibility and slow initial corrosion rates. The macromolecules were synthesized using a thiol-ene radical photopolymerization technique and then utilized to modify magnesium (Mg) alloy (AZ31) surfaces via an anhydrous phase deposition of the silane functional groups. X-ray photoelectron spectroscopy surface analysis results indicated successful surface modification based on increased nitrogen and phosphorus or sulfur composition on the modified surfaces relative to unmodified AZ31. In vitro acute thrombogenicity assessment after ovine blood contact with the PCSSi and SBSSi modified surfaces showed a significant decrease in platelet deposition and bulk phase platelet activation compared with the control alloy surfaces. Potentiodynamic polarization and electrochemical impedance spectroscopy data obtained from electrochemical corrosion testing demonstrated increased corrosion resistance for PCSSi- and SBSSi-modified AZ31 versus unmodified surfaces. The developed coating technique using PCSSi or SBSSi showed promise in acutely reducing both the corrosion and thrombotic processes, which would be attractive for application to blood contacting devices, such as vascular stents, made from degradable Mg alloys.

High-aspect ratio micro- and nanostructures enabled by photo-electrochemical etching for sensing and energy harvesting applications

NASA Astrophysics Data System (ADS)

Alhalaili, Badriyah; Dryden, Daniel M.; Vidu, Ruxandra; Ghandiparsi, Soroush; Cansizoglu, Hilal; Gao, Yang; Saif Islam, M.

2018-03-01

Photo-electrochemical (PEC) etching can produce high-aspect ratio features, such as pillars and holes, with high anisotropy and selectivity, while avoiding the surface and sidewall damage caused by traditional deep reactive ion etching (DRIE) or inductively coupled plasma (ICP) RIE. Plasma-based techniques lead to the formation of dangling bonds, surface traps, carrier leakage paths, and recombination centers. In pursuit of effective PEC etching, we demonstrate an optical system using long wavelength (λ = 975 nm) infra-red (IR) illumination from a high-power laser (1-10 W) to control the PEC etching process in n-type silicon. The silicon wafer surface was patterned with notches through a lithography process and KOH etching. Then, PEC etching was introduced by illuminating the backside of the silicon wafer to enhance depth, resulting in high-aspect ratio structures. The effect of the PEC etching process was optimized by varying light intensities and electrolyte concentrations. This work was focused on determining and optimizing this PEC etching technique on silicon, with the goal of expanding the method to a variety of materials including GaN and SiC that are used in designing optoelectronic and electronic devices, sensors and energy harvesting devices.

An Electrochemical Impedance Spectroscopy System for Monitoring Pineapple Waste Saccharification

PubMed Central

Conesa, Claudia; Ibáñez Civera, Javier; Seguí, Lucía; Fito, Pedro; Laguarda-Miró, Nicolás

2016-01-01

Electrochemical impedance spectroscopy (EIS) has been used for monitoring the enzymatic pineapple waste hydrolysis process. The system employed consists of a device called Advanced Voltammetry, Impedance Spectroscopy & Potentiometry Analyzer (AVISPA) equipped with a specific software application and a stainless steel double needle electrode. EIS measurements were conducted at different saccharification time intervals: 0, 0.75, 1.5, 6, 12 and 24 h. Partial least squares (PLS) were used to model the relationship between the EIS measurements and the sugar determination by HPAEC-PAD. On the other hand, artificial neural networks: (multilayer feed forward architecture with quick propagation training algorithm and logistic-type transfer functions) gave the best results as predictive models for glucose, fructose, sucrose and total sugars. Coefficients of determination (R2) and root mean square errors of prediction (RMSEP) were determined as R2 > 0.944 and RMSEP < 1.782 for PLS and R2 > 0.973 and RMSEP < 0.486 for artificial neural networks (ANNs), respectively. Therefore, a combination of both an EIS-based technique and ANN models is suggested as a promising alternative to the traditional laboratory techniques for monitoring the pineapple waste saccharification step. PMID:26861317

Electrochemical fluorination of La(2)CuO(4): a mild "chimie douce" route to superconducting oxyfluoride materials.

PubMed

Delville, M H; Barbut, D; Wattiaux, A; Bassat, J M; Ménétrier, M; Labrugère, C; Grenier, J C; Etourneau, J

2009-08-17

The fluorination of La(2)CuO(4) was achieved for the first time under normal conditions of pressure and temperature (1 MPa and 298 K) via electrochemical insertion in organic fluorinated electrolytes and led to lanthanum oxyfluorides of general formula La(2)CuO(4)F(x). Analyses showed that, underneath a very thin layer of LaF(3) (a few atomic layers), fluorine is effectively inserted in the material's structure. The fluorination strongly modifies the lanthanum environment, whereas very little modification is observed on copper, suggesting an insertion in the La(2)O(2) blocks of the structure. In all cases, fluorine insertion breaks the translation symmetry and introduces a long-distance disorder, as shown by electron spin resonance. These results highlight the efficiency of electrochemistry as a new "chimie douce" type fluorination technique for solid-state materials. Performed at room temperature, it additionally does not require any specific experimental care. The choice of the electrolytic medium is crucial with regard to the fluorine insertion rate as well as the material deterioration. Successful application of this technique to the well-known La(2)CuO(4) material provides a basis for further syntheses from other oxides.

Room-Temperature, Ambient-Pressure Chemical Synthesis of Amine-Functionalized Hierarchical Carbon-Sulfur Composites for Lithium-Sulfur Battery Cathodes.

PubMed

Chae, Changju; Kim, Jinmin; Kim, Ju Young; Ji, Seulgi; Lee, Sun Sook; Kang, Yongku; Choi, Youngmin; Suk, Jungdon; Jeong, Sunho

2018-02-07

Recently, the achievement of newly designed carbon-sulfur composite materials has attracted a tremendous amount of attention as high-performance cathode materials for lithium-sulfur batteries. To date, sulfur materials have been generally synthesized by a sublimation technique in sealed containers. This is a well-developed technique for the synthesizing of well-ordered sulfur materials, but it is limited when used to scale up synthetic procedures for practical applications. In this study, we suggest an easily scalable, room-temperature/ambient-pressure chemical pathway for the synthesis of highly functioning cathode materials using electrostatically assembled, amine-terminated carbon materials. It is demonstrated that stable cycling performance outcomes are achievable with a capacity of 730 mAhg -1 at a current density of 1 C with good cycling stability by a virtue of the characteristic chemical/physical properties (a high conductivity for efficient charge conduction and the presence of a number of amine groups that can interact with sulfur atoms during electrochemical reactions) of composite materials. The critical roles of conductive carbon moieties and amine functional groups inside composite materials are clarified with combinatorial analyses by X-ray photoelectron spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy.

Interconnected V2O5 nanoporous network for high-performance supercapacitors.

PubMed

Saravanakumar, B; Purushothaman, Kamatchi K; Muralidharan, G

2012-09-26

Vanadium pentoxide (V(2)O(5)) has attracted attention for supercapcitor applications because of its extensive multifunctional properties. In the present study, V(2)O(5) nanoporous network was synthesized via simple capping-agent-assisted precipitation technique and it is further annealed at different temperatures. The effect of annealing temperature on the morphology, electrochemical and structural properties, and stability upon oxidation-reduction cycling has been analyzed for supercapacitor application. We achieved highest specific capacitance of 316 F g(-1) for interconnected V(2)O(5) nanoporous network. This interconnected nanoporous network creates facile nanochannels for ion diffusion and facilitates the easy accessibility of ions. Moreover, after six hundred consecutive cycling processes the specific capacitance has changed only by 24%. A simple cost-effective preparation technique of V(2)O(5) nanoporous network with excellent capacitive behavior, energy density, and stability encourages its possible commercial exploitation for the development of high-performance supercapacitors.

Ultraflexible and robust graphene supercapacitors printed on textiles for wearable electronics applications

NASA Astrophysics Data System (ADS)

Abdelkader, Amr M.; Karim, Nazmul; Vallés, Cristina; Afroj, Shaila; Novoselov, Kostya S.; Yeates, Stephen G.

2017-09-01

Printed graphene supercapacitors have the potential to empower tomorrow’s wearable electronics. We report a solid-state flexible supercapacitor device printed on textiles using graphene oxide ink and a screen-printing technique. After printing, graphene oxide was reduced in situ via a rapid electrochemical method avoiding the use of any reducing reagents that may damage the textile substrates. The printed electrodes exhibited excellent mechanical stability due to the strong interaction between the ink and textile substrate. The unique hierarchical porous structure of the electrodes facilitated ionic diffusion and maximised the surface area available for the electrolyte/active material interface. The obtained device showed outstanding cyclic stability over 10 000 cycles and maintained excellent mechanical flexibility, which is necessary for wearable applications. The simple printing technique is readily scalable and avoids the problems associated with fabricating supercapacitor devices made of conductive yarn, as previously reported in the literature.

Metallographic examination of TD-nickel base alloys. [thermal and chemical etching technique evaluation

NASA Technical Reports Server (NTRS)

Kane, R. D.; Petrovic, J. J.; Ebert, L. J.

1975-01-01

Techniques are evaluated for chemical, electrochemical, and thermal etching of thoria dispersed (TD) nickel alloys. An electrochemical etch is described which yielded good results only for large grain sizes of TD-nickel. Two types of thermal etches are assessed for TD-nickel: an oxidation etch and vacuum annealing of a polished specimen to produce an etch. It is shown that the first etch was somewhat dependent on sample orientation with respect to the processing direction, the second technique was not sensitive to specimen orientation or grain size, and neither method appear to alter the innate grain structure when the materials were fully annealed prior to etching. An electrochemical etch is described which was used to observe the microstructures in TD-NiCr, and a thermal-oxidation etch is shown to produce better detail of grain boundaries and to have excellent etching behavior over the entire range of grain sizes of the sample.

Enzyme-based electrochemical biosensors for determination of organophosphorus and carbamate pesticides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Everett, W.R.; Rechnitz, G.A.

1999-01-01

A mini review of enzyme-based electrochemical biosensors for inhibition analysis of organophosphorus and carbamate pesticides is presented. Discussion includes the most recent literature to present advances in detection limits, selectivity and real sample analysis. Recent reviews on the monitoring of pesticides and their residues suggest that the classical analytical techniques of gas and liquid chromatography are the most widely used methods of detection. These techniques, although very accurate in their determinations, can be quite time consuming and expensive and usually require extensive sample clean up and pro-concentration. For these and many other reasons, the classical techniques are very difficult tomore » adapt for field use. Numerous researchers, in the past decade, have developed and made improvements on biosensors for use in pesticide analysis. This mini review will focus on recent advances made in enzyme-based electrochemical biosensors for the determinations of organophosphorus and carbamate pesticides.« less

Corrosive effect of the type of soil in the systems of grounding more used (copper and stainless steel) for local soil samples from the city of Tunja (Colombia), by means of electrochemical techniques

NASA Astrophysics Data System (ADS)

Guerrero, L.; Salas, Y.; Blanco, J.

2016-02-01

In this work electrochemical techniques were used to determine the corrosion behaviour of copper and stainless steel electrodes, used in grounding varying soil type with which they react. A slight but significant change in the corrosion rate, linear polarization resistance and equivalent parameters in the technique of electrochemical impedance spectroscopy circuit was observed. Electrolytes in soils are slightly different depending on laboratory study, but the influence was noted in the retention capacity of water, mainly due to clays, affecting ion mobility and therefore measures such as the corrosion rate. Behaviour was noted in lower potential for copper corrosion, though the corrosion rate regardless of the type of soil, was much higher for electrodes based on copper, by several orders of magnitude.

Application of Electro Chemical Machining for materials used in extreme conditions

NASA Astrophysics Data System (ADS)

Pandilov, Z.

2018-03-01

Electro-Chemical Machining (ECM) is the generic term for a variety of electrochemical processes. ECM is used to machine work pieces from metal and metal alloys irrespective of their hardness, strength or thermal properties, through the anodic dissolution, in aerospace, automotive, construction, medical equipment, micro-systems and power supply industries. The Electro Chemical Machining is extremely suitable for machining of materials used in extreme conditions. General overview of the Electro-Chemical Machining and its application for different materials used in extreme conditions is presented.

Corrosion Performance of High Damping Alloys in 3.5% Sodium Chloride Environment.

DTIC Science & Technology

1987-09-01

Electrochemical Technique, Sea Exposure, Scanning Electron Microscopy. 9 .,5MAZT (Continue on rvre of necessary ad 4*er.#y by boock numbver# -The... electrochemical nature of corrosion provides a means of determining an almost instantaneous corrosion rate. Corrosion rate and the nature of corrosion attack were... electrochemical nature of corrosion provides a means of determining an almost instantaneous corrosion rate. Corrosion rate and the nature of

Fully integrated three-dimensional electrodes for electrochemical detection in microchips: fabrication, characterization, and applications.

PubMed

Pai, Rekha S; Walsh, Kevin M; Crain, Mark M; Roussel, Thomas J; Jackson, Douglas J; Baldwin, Richard P; Keynton, Robert S; Naber, John F

2009-06-15

A scalable and rather inexpensive solution to producing microanalytical systems with "on-chip" three-dimensional (3D) microelectrodes is presented in this study, along with applicability to practical electrochemical (EC) detection scenarios such as preconcentration and interferant removal. This technique to create high-aspect-ratio (as much as 4:1) gold microstructures in constrained areas involved the modification of stud bump geometry with microfabricated silicon molds via an optimized combination of temperature, pressure, and time. The microelectrodes that resulted consisted of an array of square pillars approximately 18 microm tall and 20 microm wide on each side, placed at the end of a microfabricated electrophoresis channel. This technique increased the active surface area of the microelectrodes by as much as a factor of 50, while mass transfer and, consequently, preconcentration collection efficiencies were increased to approximately 100%, compared to approximately 30% efficiency for planar nonmodified microelectrodes (samples that were used included the neurotransmitters dopamine and catechol). The 3D microelectrodes were used both in a stand-alone configuration, for direct EC detection of model catecholamine analytes, and, more interestingly, in dual electrode configurations for EC sample processing prior to detection downstream at a second planar electrode. In particular, the 3D electrodes were shown to be capable of performing coulometry or complete (100%) redox conversion of analyte species over a wide range of concentrations, from 4.3 microM to 4.4 mM, in either plug-flow or continuous-flow formats.

First-principles data-driven discovery of transition metal oxides for artificial photosynthesis

NASA Astrophysics Data System (ADS)

Yan, Qimin

We develop a first-principles data-driven approach for rapid identification of transition metal oxide (TMO) light absorbers and photocatalysts for artificial photosynthesis using the Materials Project. Initially focusing on Cr, V, and Mn-based ternary TMOs in the database, we design a broadly-applicable multiple-layer screening workflow automating density functional theory (DFT) and hybrid functional calculations of bulk and surface electronic and magnetic structures. We further assess the electrochemical stability of TMOs in aqueous environments from computed Pourbaix diagrams. Several promising earth-abundant low band-gap TMO compounds with desirable band edge energies and electrochemical stability are identified by our computational efforts and then synergistically evaluated using high-throughput synthesis and photoelectrochemical screening techniques by our experimental collaborators at Caltech. Our joint theory-experiment effort has successfully identified new earth-abundant copper and manganese vanadate complex oxides that meet highly demanding requirements for photoanodes, substantially expanding the known space of such materials. By integrating theory and experiment, we validate our approach and develop important new insights into structure-property relationships for TMOs for oxygen evolution photocatalysts, paving the way for use of first-principles data-driven techniques in future applications. This work is supported by the Materials Project Predictive Modeling Center and the Joint Center for Artificial Photosynthesis through the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract No. DE-AC02-05CH11231. Computational resources also provided by the Department of Energy through the National Energy Supercomputing Center.

Creating an Electronic Reference and Information Database for Computer-aided ECM Design

NASA Astrophysics Data System (ADS)

Nekhoroshev, M. V.; Pronichev, N. D.; Smirnov, G. V.

2018-01-01

The paper presents a review on electrochemical shaping. An algorithm has been developed to implement a computer shaping model applicable to pulse electrochemical machining. For that purpose, the characteristics of pulse current occurring in electrochemical machining of aviation materials have been studied. Based on integrating the experimental results and comprehensive electrochemical machining process data modeling, a subsystem for computer-aided design of electrochemical machining for gas turbine engine blades has been developed; the subsystem was implemented in the Teamcenter PLM system.

Electrochemical Fabrication of Metallic Quantum Wires

ERIC Educational Resources Information Center

Tao, Nongjian

2005-01-01

The fabrication of metallic quantum wires using simple electrochemical techniques is described. The conductance of the system can be readily measured that allows one to constantly monitor the conductance during fabrication and use conductance quantization as a signature to guide the fabrication.

Platinum nanowire microelectrode arrays for neurostimulation applications: Fabrication, characterization, and in-vitro retinal cell stimulation

NASA Astrophysics Data System (ADS)

Whalen, John J., III

Implantable electrical neurostimulating devices are being developed for a number of applications, including artificial vision through retinal stimulation. The epiretinal prosthesis will use a two-dimensional array microelectrodes to address individual cells of the retina. MEMS fabrication processes can produce arrays of microelectrodes with these dimensions, but there are two critical issues that they cannot satisfy. One, the stimulating electrodes are the only part of the implanted electrical device that penetrate through the water impermeable package, and must do so without sacrificing hermeticity. Two, As electrode size decreases, the current density (A cm-2 ) increases, due to increased electrochemical impedance. This reduces the amount of charge that can be safely injected into the tissue. To date, MEMS processing method, cannot produce electrode arrays with good, prolonged hermetic properties. Similarly, MEMS approaches do not account for the increased impedance caused by decreased surface area. For these reasons there is a strong motivation for the development of a water-impermeable, substrate-penetrating electrode array with low electrochemical impedance. This thesis presents a stimulating electrode array fabricated from platinum nanowires using a modified electrochemical template synthesis approach. Nanowires are electrochemically deposited from ammonium hexachloroplatinate solution into lithographically patterned nanoporous anodic alumina templates to produce microarrays of platinum nanowires. The platinum nanowires penetrating through the ceramic aluminum oxide template serve as parallel electrical conduits through the water impermeable, electrically insulating substrate. Electrode impedance can be adjusted by either controlling the nanowire hydrous platinum oxide content or by partially etching the alumina template to expose additional surface area. A stepwise approach to this project was taken. First, the electrochemistry of ammonium hexachloroplatinate solution was characterized, and physical properties of electrodeposited thin films were correlated to deposition conditions used. Second, platinum nanowires were fabricated and their properties characterized, using similar deposition conditions. Third, the feasibility of fabricating platinum nanowire stimulating electrode arrays with a variety of surface structures was demonstrated. Fourth, the enhanced charge transfer characteristics of these structures were demonstrated using electrochemical techniques. Finally, retinal cell stimulation was demonstrated using electrodes from platinum nanowire arrays.

Electrochemical and AFM Characterization of G-Quadruplex Electrochemical Biosensors and Applications

PubMed Central

2018-01-01

Guanine-rich DNA sequences are able to form G-quadruplexes, being involved in important biological processes and representing smart self-assembling nanomaterials that are increasingly used in DNA nanotechnology and biosensor technology. G-quadruplex electrochemical biosensors have received particular attention, since the electrochemical response is particularly sensitive to the DNA structural changes from single-stranded, double-stranded, or hairpin into a G-quadruplex configuration. Furthermore, the development of an increased number of G-quadruplex aptamers that combine the G-quadruplex stiffness and self-assembling versatility with the aptamer high specificity of binding to a variety of molecular targets allowed the construction of biosensors with increased selectivity and sensitivity. This review discusses the recent advances on the electrochemical characterization, design, and applications of G-quadruplex electrochemical biosensors in the evaluation of metal ions, G-quadruplex ligands, and other small organic molecules, proteins, and cells. The electrochemical and atomic force microscopy characterization of G-quadruplexes is presented. The incubation time and cations concentration dependence in controlling the G-quadruplex folding, stability, and nanostructures formation at carbon electrodes are discussed. Different G-quadruplex electrochemical biosensors design strategies, based on the DNA folding into a G-quadruplex, the use of G-quadruplex aptamers, or the use of hemin/G-quadruplex DNAzymes, are revisited. PMID:29666699

100-Fold Enhancement of Charge Transport in Uniaxially Oriented Mesoporous Anatase TiO 2 Films

DOE PAGES

Li, Ke; Liu, Jie; Sheng, Xia; ...

2017-12-04

Mesoporous semiconductor films are of considerable interest for applications in photoelectrochemical devices, however, despite intensive research till now, their charge transport properties remain significantly lower than their single-crystal counterparts. Herein, we report a novel low-temperature template-free technique for growing high surface area mesoporous anatase TiO2 films with a preferred [001] crystalline-orientation on FTO-coated glass substrate. Compared to mesoporous films that comprised of randomly oriented crystallites, the uniaxial orientation enables a 100-fold increase in the rate of electron transport. The uniaxially oriented mesoporous anatase TiO2 films exhibit should greatly facilitate the development and application of photoelectrochemical and electrochemical devices.

Conducting Polymeric Hydrogel Electrolyte Based on Carboxymethylcellulose and Polyacrylamide/Polyaniline for Supercapacitor Applications

NASA Astrophysics Data System (ADS)

Suganya, N.; Jaisankar, V.; Sivakumar, E. K. T.

Conducting polymer hydrogels represent a unique class of materials that possess enormous application in flexible electronic devices. In the present work, conducting carboxymethylcellulose (CMC)-co-polyacrylamide (PAAm)/polyaniline was synthesized by a two-step interpenetrating network solution polymerization technique. The synthesized CMC-co-PAAm/polyaniline with interpenetrating network structure was prepared by in situ polymerization of aniline to enhance conductivity. The molecular structure and morphology of the copolymer hydrogels were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The novel conducting polymer hydrogels show good electrical and electrochemical behavior, which makes them potentially useful in electronic devices such as supercapacitors, biosensors, bioelectronics, solar cells and memory devices.

Optical polarimetry: Instrumentation and applications; Proceedings of the Seminar, San Diego, Calif., August 23, 24, 1977

NASA Technical Reports Server (NTRS)

Azzam, R. M. A. (Editor); Coffeen, D. L.

1977-01-01

Instrumentation used in optical polarimetry is discussed with reference to high-resolution spectropolarimetry, an orbiter cloud photopolarimeter, X-ray polarimeters, and the design of a self-nulling ellipsometer. Consideration is given to surface and thin-film ellipsometry noting studies of electrochemical surface layers, surface anisotropy, polish layers on infrared window materials, and anodic films. Papers on biological, chemical, and physical polarimetry are presented including birefringence in biological materials, vibrational optical activity, and the optical determination of the thermodynamic phase diagram of a metamagnet. Remote sensing is discussed in terms of polarization imagery, the optical polarimetry of particulate surfaces, and techniques and applications of elliptical polarimetry in astronomy and atmospheric studies.

Reduced Graphene Oxide/Carbon Nanotube Composites as Electrochemical Energy Storage Electrode Applications.

PubMed

Yang, Wenyao; Chen, Yan; Wang, Jingfeng; Peng, Tianjun; Xu, Jianhua; Yang, Bangchao; Tang, Ke

2018-06-15

We demonstrate an electrochemical reduction method to reduce graphene oxide (GO) to electrochemically reduced graphene oxide (ERGO) with the assistance of carbon nanotubes (CNTs). The faster and more efficient reduction of GO can be achieved after proper addition of CNTs into GO during the reduction process. This nanotube/nanosheet composite was deposited on electrode as active material for electrochemical energy storage applications. It has been found that the specific capacitance of the composite film was strongly affected by the mass ratio of GO/CNTs and the scanning ratio of cyclic voltammetry. The obtained ERGO/CNT composite electrode exhibited a 279.4 F/g-specific capacitance and showed good cycle rate performance with the evidence that the specific capacitance maintained above 90% after 6000 cycles. The synergistic effect between ERGO and CNTs as well as crossing over of CNTs into ERGO is attributed to the high electrochemical performance of composite electrode.

Electrochemical deposition of silver crystals aboard Skylab 4

NASA Technical Reports Server (NTRS)

Grodzka, P. G.; Facemire, B. R.; Johnston, M. H.; Gates, D. W.

1976-01-01

Silver crystals were grown aboard Skylab 4 by an electro-chemical reaction and subsequently returned to earth for comparison with crystals grown at 1- and 5-g. Both the Skylab and earth-grown crystals show a variety of structures. Certain tendencies in structure dependency on gravity level, however, can be discerned. In addition, downward growing dendrite streamers; upward growing chunky crystal streamers; growth along an air/liquid interface; and ribbon, film, and fiber crystal habits were observed in experiments conducted on the ground with solutions of varying concentrations. It was also observed that the crystal structures of space and ground electro-deposited silver crystals were very similar to the structures of germanium selenide and germanium telluride crystals grown in space and on the ground by a vapor transport technique. Consideration of the data leads to the conclusions that: (1) the rate of electrochemical displacement of silver ions from a 5 percent aqueous solution by copper is predominantly diffussion controlled in space and kinetically controlled in 1- and higher-g because of augmentation of mass transport by convection; (2) downward and upward crystal streamers are the result of gravity-driven convection, the flow patterns of which can be delineated. Lateral growths along an air/liquid interface are the result of surface-tension-driven convection, the pattern of which also can be delineated; (3) electrolysis in space or low-g environments can produce either dendritic crystals with more perfect microcrystalline structures or massive, single crystals with fewer defects than those grown on ground or at higher g-levels. Ribbons or films of space-grown silicon crystals would find a ready market for electronic substrate and photocell applications. Space-grown dendritic, metal crystals present the possibility of unique catalysts. Large perfect crystals of various materials are desired for a number of electronic and optical applications; and (4) vapor transport growth of germanium selenide and germanium telluride is affected by convection mechanisms similar to the mechanisms hypothesized for the electrochemical deposition of silver crystals. Evidence and considerations leading to the preceding summaries and conclusions are presented. The implications of the findings and conclusions for technological applications are discussed, and recommendations for further experiments are presented.

Corrosion inhibition performance of imidazolium ionic liquids and their influence on surface ferrous carbonate layer formation

NASA Astrophysics Data System (ADS)

Yang, Dongrui

Corrosion inhibitors as effective anti-corrosion applications were widely studied and drawn much attention in both academe and industrial area. In this work, a systematic work, including inhibitors selection, anti-corrosion property and characterization, influence on scale formation, testing system design and so on, were reported. The corrosion inhibition performance of four imidazolium ionic liquids in carbon dioxide saturated NaCl solution was investigated by using electrochemical and surface analysis technologies. The four compounds are 1-ethyl-3-methylimidazolium chloride (a), 1-butyl-3-methylimidazolium chloride (b), 1-hexyl-3-methylimidazolium chloride (c), 1-decyl-3-methylimidazolium chloride (d). Under the testing conditions, compound d showed the highest inhibition efficiency and selected as the main object of further study. As a selected representative formula, 1-decyl-3-methylimidazolium chloride was studied in detail about its corrosion inhibition performance on mild steel in carbon dioxide saturated NaCl brine at pH 3.8 and 6.8. Electrochemical and surface analysis techniques were used to characterize the specimen corrosion process during the immersion in the blank and inhibiting solutions. The precorrosion of specimen surface showed significant and different influences on the anti-corrosion property of DMICL at pH 3.8 and 6.8. The corrosion inhibition efficiency (IE) was calculated based on parameters obtained from electrochemical techniques; the achieved IE was higher than 98% at the 25th hour for the steel with a well-polished surface at pH 3.8. The fitting parameters obtained from electrochemical data helped to account for the interfacial changes. As proved in previous research, 1-decyl-3-methylimidazolium chloride could be used as good corrosion inhibitors under certain conditions. However, under other conditions, such chemicals, as well as other species in oil transporting system, could be a factor influencing the evolution of protective surface inorganic layer. In this part, the FeCO3 layer evolution process for API 5L X52 carbon steel in CO2-saturated NaCl brine in the absence and in the presence of 1-decyl-3-methylimidazolium chloride ionic liquid was characterized using electrochemical techniques. Two models were developed to account for the interfacial evolution: the first model considered the balance of positive and negative charges at the interface of the metal and electrolyte in blank solution, while the second one considered the layer coverage and evolution with the imidazolium compound. The corrosion testing system is scientifically and practically critical for corrosion testing and simulations. In this part, a flowing fluid loop cell (FFLC) system was constructed to simulate the corrosion environment in the pipeline. Main content of this work include the construction of the flowing fluid cell loop (FFLC) system, as well as FFLC-based corrosion/anticorrosion tests under simulated acid conditions. Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Resistance (LPR) were used as prime techniques to quantify and characterize the corrosion behaviors of carbon steel specimen. The Eff vs. Reynolds number (Re) plots for the specimen located in the chamber and in the loop branch were provided.

Solid-state supercapacitors with ionic liquid gel polymer electrolyte based on poly (3, 4-ethylenedioxythiophene), carbon nanotubes, and metal oxides nanocomposites for electrical energy storage

NASA Astrophysics Data System (ADS)

Obeidat, Amr M.

Clean and renewable energy systems have emerged as an important area of research having diverse and significant new applications. These systems utilize different energy storage methods such as the batteries and supercapacitors. Supercapacitors are electrochemical energy storage devices that are designed to bridge the gap between batteries and conventional capacitors. Supercapacitors which store electrical energy by electrical double layer capacitance are based on large surface area structured carbons. The materials systems in which the Faradaic reversible redox reactions store electrical energy are the transition metal oxides and electronically conducting polymers. Among the different types of conducting polymers, poly (3, 4- ethylenedioxythiophene) (PEDOT) is extensively investigated owing to its chemical and mechanical stability. Due to instability of aqueous electrolytes at high voltages and toxicity of organic electrolytes, potential of supercapacitors has not been fully exploited. A novel aspect of this work is in utilizing the ionic liquid gel polymer electrolyte to design solid-state supercapacitors for energy storage. Various electrochemical systems were investigated including graphene, PEDOT, PEDOT-carbon nanotubes, PEDOT-manganese oxide, and PEDOT-iron oxide nanocomposites. The electrochemical performance of solid-state supercapacitor devices was evaluated based on cyclic voltammetry (CV), charge-discharge (CD), prolonged cyclic tests, and electrochemical impedance spectroscopy (EIS) techniques. Raman spectroscopy technique was also utilized to analyze the bonding structure of the electrode materials. The graphene solid-state supercapacitor system displayed areal capacitance density of 141.83 mF cm-2 based on high potential window up to 4V. The PEDOT solid-state supercapacitor system was synthesized in acetonitrile and aqueous mediums achieving areal capacitance density of 219.17 mF cm-2. The hybrid structure of solid-state supercapacitors was also studied in solid-state design based on PEDOT and graphene electrodes that produced areal capacitance density of 198.26 mF cm-2. Symmetrical PEDOT-manganese oxide nanocomposites were synthesized by co-deposition and dip-coating techniques to fabricate solid-state supercapacitor systems achieving areal capacitance density of 122.08 mF cm-2 credited to the PEDOT-MnO2 supercapacitor that was synthesized by dipping the PEDOT electrode in pure KMnO4 solution. The electrochemical performance of PEDOT-carbon nanotube solid-state supercapacitors was also investigated in both acetonitrile and aqueous medium showing good dispersion characteristics with optimum CNT content of 1 mg. The PEDOT-CNT solid-state supercapacitor system synthesized in acetonitrile displayed areal capacitance density of 297.43 mF cm-2. PEDOT-Fe2O3 nanocomposites were synthesized by single-step co-deposition techniques, and these were used to fabricate solid-state supercapacitors achieving areal capacitance density of 96.89 mF cm-2. Furthermore, some of these thin flexible solid-state supercapacitors were integrated with solar cells for direct storage of solar electricity, which proved to be promising as autonomous power source for flexible and wearable electronics. This dissertation describes the electrode synthesis, design and properties of solid-state supercapacitors, and their electrochemical performance in the storage of electrical energy.

A novel quantitative electrochemical method to monitor DNA double-strand breaks caused by a DNA cleavage agent at a DNA sensor.

PubMed

Banasiak, Anna; Cassidy, John; Colleran, John

2018-06-01

To date, DNA cleavage, caused by cleavage agents, has been monitored mainly by gel and capillary electrophoresis. However, these techniques are time-consuming, non-quantitative and require gel stains. In this work, a novel, simple and, importantly, a quantitative method for monitoring the DNA nuclease activity of potential anti-cancer drugs, at a DNA electrochemical sensor, is presented. The DNA sensors were prepared using thiol-modified oligonucleotides that self-assembled to create a DNA monolayer at gold electrode surfaces. The quantification of DNA double-strand breaks is based on calculating the DNA surface coverage, before and after exposure to a DNA cleavage agent. The nuclease properties of a model DNA cleavage agent, copper bis-phenanthroline ([Cu II (phen) 2 ] 2+ ), that can cleave DNA in a Fenton-type reaction, were quantified electrochemically. The DNA surface coverage decreased on average by 21% after subjecting the DNA sensor to a nuclease assay containing [Cu II (phen) 2 ] 2+ , a reductant and an oxidant. This percentage indicates that 6 base pairs were cleaved in the nuclease assay from the immobilised 30 base pair strands. The DNA cleavage can be also induced electrochemically in the absence of a chemical reductant. [Cu II (phen) 2 ] 2+ intercalates between DNA base pairs and, on application of a suitable potential, can be reduced to [Cu I (phen) 2 ] + , with dissolved oxygen acting as the required oxidant. This reduction process is facilitated through DNA strands via long-range electron transfer, resulting in DNA cleavage of 23%. The control measurements for both chemically and electrochemically induced cleavage revealed that DNA strand breaks did not occur under experimental conditions in the absence of [Cu II (phen) 2 ] 2+ . Copyright © 2018 Elsevier B.V. All rights reserved.

Layered double hydroxide materials coated carbon electrode: New challenge to future electrochemical power devices

NASA Astrophysics Data System (ADS)

Djebbi, Mohamed Amine; Braiek, Mohamed; Namour, Philippe; Ben Haj Amara, Abdesslem; Jaffrezic-Renault, Nicole

2016-11-01

Layered double hydroxides (LDHs) have been widely used in the past years due to their unique physicochemical properties and promising applications in electroanalytical chemistry. The present paper is going to focus exclusively on magnesium-aluminum and zinc-aluminum layered double hydroxides (MgAl & ZnAl LDHs) in order to investigate the property and structure of active cation sites located within the layer structure. The MgAl and ZnAl LDH nanosheets were prepared by the constant pH co-precipitation method and uniformly supported on carbon-based electrode materials to fabricate an LDH electrode. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy revealed the LDH form and well-crystallized materials. Wetting surface properties (hydrophilicity and hydrophobicity) of both prepared LDHs were recorded by contact angle measurement show hydrophilic character and basic property. The electrochemical performance of these hybrid materials was investigated by mainly cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry techniques to identify the oxidation/reduction processes at the electrode/electrolyte interface and the effect of the divalent metal cations in total reactivity. The hierarchy of the modified electrode proves that the electronic conductivity of the bulk material is considerably dependent on the divalent cation and affects the limiting parameter of the overall redox process. However, MgAl LDH shows better performance than ZnAl LDH, due to the presence of magnesium cations in the layers. Following the structural, morphological and electrochemical behavior studies of both synthesized LDHs, the prepared LDH modified electrodes were tested through microbial fuel cell configuration, revealing a remarkable, potential new pathway for high-performance and cost-effective electrode use in electrochemical power devices.

The application of electrochemistry to pharmaceutical stability testing--comparison with in silico prediction and chemical forced degradation approaches.

PubMed

Torres, Susana; Brown, Roland; Szucs, Roman; Hawkins, Joel M; Zelesky, Todd; Scrivens, Garry; Pettman, Alan; Taylor, Mark R

2015-11-10

The aim of this study was to evaluate the use of electrochemistry to generate oxidative degradation products of a model pharmaceutical compound. The compound was oxidized at different potentials using an electrochemical flow-cell fitted with a glassy carbon working electrode, a Pd/H2 reference electrode and a titanium auxiliary electrode. The oxidative products formed were identified and structurally characterized by LC-ESI-MS/MS using a high resolution Q-TOF mass spectrometer. Results from electrochemical oxidation using electrolytes of different pH were compared to those from chemical oxidation and from accelerated stability studies. Additionally, oxidative degradation products predicted using an in silico commercially available software were compared to those obtained from the various experimental methods. The electrochemical approach proved to be useful as an oxidative stress test as all of the final oxidation products observed under accelerated stability studies could be generated; previously reported reactive intermediate species were not observed most likely because the electrochemical mechanism differs from the oxidative pathway followed under accelerated stability conditions. In comparison to chemical degradation tests electrochemical degradation has the advantage of being much faster and does not require the use of strong oxidizing agents. Moreover, it enables the study of different operating parameters in short periods of time and optimisation of the reaction conditions (pH and applied potential) to achieve different oxidative products mixtures. This technique may prove useful as a stress test condition for the generation of oxidative degradation products and may help accelerate structure elucidation and development of stability indicating analytical methods. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermo-electrochemical evaluation of lithium-ion batteries for space applications

NASA Astrophysics Data System (ADS)

Walker, W.; Yayathi, S.; Shaw, J.; Ardebili, H.

2015-12-01

Advanced energy storage and power management systems designed through rigorous materials selection, testing and analysis processes are essential to ensuring mission longevity and success for space exploration applications. Comprehensive testing of Boston Power Swing 5300 lithium-ion (Li-ion) cells utilized by the National Aeronautics and Space Administration (NASA) to power humanoid robot Robonaut 2 (R2) is conducted to support the development of a test-correlated Thermal Desktop (TD) Systems Improved Numerical Differencing Analyzer (SINDA) (TD-S) model for evaluation of power system thermal performance. Temperature, current, working voltage and open circuit voltage measurements are taken during nominal charge-discharge operations to provide necessary characterization of the Swing 5300 cells for TD-S model correlation. Building from test data, embedded FORTRAN statements directly simulate Ohmic heat generation of the cells during charge-discharge as a function of surrounding temperature, local cell temperature and state of charge. The unique capability gained by using TD-S is demonstrated by simulating R2 battery thermal performance in example orbital environments for hypothetical extra-vehicular activities (EVA) exterior to a small satellite. Results provide necessary demonstration of this TD-S technique for thermo-electrochemical analysis of Li-ion cells operating in space environments.

Application of morphological synthesis for understanding electrode microstructure evolution as a function of applied charge/discharge cycles

DOE PAGES

Glazoff, Michael V.; Dufek, Eric J.; Shalashnikov, Egor V.

2016-09-15

Morphological analysis and synthesis operations were employed for analysis of electrode microstructure transformations and evolution accompanying the application of charge/discharge cycles to electrochemical storage systems (batteries). Using state-of-the-art morphological algorithms, it was possible to predict microstructure evolution in porous Si electrodes for Li-ion batteries with sufficient accuracy. Algorithms for image analyses (segmentation, feature extraction, and 3D-reconstructions using 2D-images) were also developed. Altogether, these techniques could be considered supplementary to phase-field mesoscopic approach to microstructure evolution that is based upon clear and definitive changes in the appearance of microstructure. However, unlike in phase-field, the governing equations for morphological approach are geometry-,more » not physics-based. Similar non-physics based approach to understanding different phenomena was attempted with the introduction of cellular automata. It is anticipated that morphological synthesis and analysis will represent a useful supplementary tool to phase-field and will render assistance to unraveling the underlying microstructure-property relationships. The paper contains data on electrochemical characterization of different electrode materials that was conducted in parallel to morphological study.« less

Large Size Color-tunable Electroluminescence from Cationic Iridium Complexes-based Light-emitting Electrochemical Cells

PubMed Central

Zeng, Qunying; Li, Fushan; Guo, Tailiang; Shan, Guogang; Su, Zhongmin

2016-01-01

Solution-processable light-emitting electrochemical cells (LECs) with simple device architecture have become an attractive candidate for application in next generation lighting and flat-panel displays. Herein, single layer LECs employing two cationic Ir(III) complexes showing highly efficient blue-green and yellow electroluminescence with peak current efficiency of 31.6 cd A−1 and 40.6 cd A−1, respectively, have been reported. By using both complexes in the device, color-tunable LECs with a single spectral peak in the wavelength range from 499 to 570 nm were obtained by varying their rations. In addition, the fabrication of efficient LECs was demonstrated based on low cost doctor-blade coating technique, which was compatible with the roll to roll fabrication process for the large size production. In this work, for the first time, 4 inch LEC devices by doctor-blade coating were fabricated, which exhibit the efficiencies of 23.4 cd A−1 and 25.4 cd A−1 for the blue-green and yellow emission, respectively. The exciting results indicated that highly efficient LECs with controllable color could be realized and find practical application in large size lighting and displays. PMID:27278527

Citrus maxima (Pomelo) juice mediated eco-friendly synthesis of ZnO nanoparticles: Applications to photocatalytic, electrochemical sensor and antibacterial activities

NASA Astrophysics Data System (ADS)

Pavithra, N. S.; Lingaraju, K.; Raghu, G. K.; Nagaraju, G.

2017-10-01

In the present work, Zinc oxide nanoparticles (ZnO Nps) have been successfully prepared through a simple, effective and low cost solution combustion method using Zn (NO3)2·6H2O as an oxidizer, chakkota (Common name = Pomelo) fruit juice as novel fuel. X-ray diffraction pattern indicates the hexagonal wurtzite structure with average crystallite size of 22 nm. ZnO Nps were characterized with the aid of different spectroscopic techniques such as Raman spectroscopy, Fourier Transform Infrared spectroscopy, Photoluminescence and UV-Visible spectroscopy. FTIR shows characteristic ZnO vibrational mode at 393 cm- 1. SEM images show that the particles are agglomerated. TEM image shows the size of the particles are about 10-20 nm. Further, in order to establish practical applicability of the synthesized ZnO Nps, photocatalytic degradation of methylene blue (MB) dye as a model system was studied in presence of UV (665 nm) light. In addition to this, the antibacterial activity was screen against 3 bacterial strains and electrochemical sensor performance towards the quantification of dopamine at nano molar concentrations was also explored.

Electrochemical Approach for Effective Antifouling and Antimicrobial Surfaces.

PubMed

Gaw, Sheng Long; Sarkar, Sujoy; Nir, Sivan; Schnell, Yafit; Mandler, Daniel; Xu, Zhichuan J; Lee, Pooi See; Reches, Meital

2017-08-09

Biofouling, the adsorption of organisms to a surface, is a major problem today in many areas of our lives. This includes: (i) health, as biofouling on medical device leads to hospital-acquired infections, (ii) water, since the accumulation of organisms on membranes and pipes in desalination systems harms the function of the system, and (iii) energy, due to the heavy load of the organic layer that accumulates on marine vessels and causes a larger consumption of fuel. This paper presents an effective electrochemical approach for generating antifouling and antimicrobial surfaces. Distinct from previously reported antifouling or antimicrobial electrochemical studies, we demonstrate the formation of a hydrogen gas bubble layer through the application of a low-voltage square-waveform pulses to the conductive surface. This electrochemically generated gas bubble layer serves as a separation barrier between the surroundings and the target surface where the adhesion of bacteria can be deterred. Our results indicate that this barrier could effectively reduce the adsorption of bacteria to the surface by 99.5%. We propose that the antimicrobial mechanism correlates with the fundamental of hydrogen evolution reaction (HER). HER leads to an arid environment that does not allow the existence of live bacteria. In addition, we show that this drought condition kills the preadhered bacteria on the surface due to water stress. This work serves as the basis for the exploration of future self-sustainable antifouling techniques such as incorporating it with photocatalytic and photoelectrochemical reactions.

Electrochemical hydrogenation of thiophene on SPE electrodes

NASA Astrophysics Data System (ADS)

Huang, Haiyan; Yuan, Penghui; Yu, Ying; Chung, Keng H.

2017-01-01

Electrochemical reduction desulfurization is a promising technology for petroleum refining which is environmental friendly, low cost and able to achieve a high degree of automation. Electrochemical hydrogenation of thiophene was performed in a three-electrode system which SPE electrode was the working electrode. The electrochemical desulfurization was studied by cyclic voltammetry and bulk electrolysis with coulometry (BEC) techniques. The results of cyclic voltammetry showed that the electrochemical hydrogenation reduction reaction occurred at -0.4V. The BEC results showed that the currents generated from thiophene hydrogenation reactions increased with temperature. According to Arrhenius equation, activation energy of thiophene electrolysis was calculated and lower activation energy value indicated it was diffusion controlled reaction. From the products of electrolytic reactions, the mechanisms of electrochemical hydrogenation of thiophene were proposed, consisting of two pathways: openingring followed by hydrogenation, and hydrogenation followed by ring opening.

Frangible electrochemical cell and sealing technique

NASA Technical Reports Server (NTRS)

Halpert, G.; Haynos, J.; Sherfey, J.

1969-01-01

Electrochemical cell assembly, which includes a positive electrode plate between two negative electrode plates, is both flexible and compact, and frangible under severe shock conditions. Leak-tight integrity of the housing is maintained by polymer-to-polymer fusion bonds through holes in the expanded metal electrode terminals.

Progress in Nano-Engineered Anodic Aluminum Oxide Membrane Development.

PubMed

Poinern, Gerrard Eddy Jai; Ali, Nurshahidah; Fawcett, Derek

2011-02-25

The anodization of aluminum is an electro-chemical process that changes the surface chemistry of the metal, via oxidation, to produce an anodic oxide layer. During this process a self organized, highly ordered array of cylindrical shaped pores can be produced with controllable pore diameters, periodicity and density distribution. This enables anodic aluminum oxide (AAO) membranes to be used as templates in a variety of nanotechnology applications without the need for expensive lithographical techniques. This review article is an overview of the current state of research on AAO membranes and the various applications of nanotechnology that use them in the manufacture of nano-materials and devices or incorporate them into specific applications such as biological/chemical sensors, nano-electronic devices, filter membranes and medical scaffolds for tissue engineering.

Progress in Nano-Engineered Anodic Aluminum Oxide Membrane Development

PubMed Central

Poinern, Gerrard Eddy Jai; Ali, Nurshahidah; Fawcett, Derek

2011-01-01

The anodization of aluminum is an electro-chemical process that changes the surface chemistry of the metal, via oxidation, to produce an anodic oxide layer. During this process a self organized, highly ordered array of cylindrical shaped pores can be produced with controllable pore diameters, periodicity and density distribution. This enables anodic aluminum oxide (AAO) membranes to be used as templates in a variety of nanotechnology applications without the need for expensive lithographical techniques. This review article is an overview of the current state of research on AAO membranes and the various applications of nanotechnology that use them in the manufacture of nano-materials and devices or incorporate them into specific applications such as biological/chemical sensors, nano-electronic devices, filter membranes and medical scaffolds for tissue engineering. PMID:28880002

The fuel cell model of abiogenesis: a new approach to origin-of-life simulations.

PubMed

Barge, Laura M; Kee, Terence P; Doloboff, Ivria J; Hampton, Joshua M P; Ismail, Mohammed; Pourkashanian, Mohamed; Zeytounian, John; Baum, Marc M; Moss, John A; Lin, Chung-Kuang; Kidd, Richard D; Kanik, Isik

2014-03-01

In this paper, we discuss how prebiotic geo-electrochemical systems can be modeled as a fuel cell and how laboratory simulations of the origin of life in general can benefit from this systems-led approach. As a specific example, the components of what we have termed the "prebiotic fuel cell" (PFC) that operates at a putative Hadean hydrothermal vent are detailed, and we used electrochemical analysis techniques and proton exchange membrane (PEM) fuel cell components to test the properties of this PFC and other geo-electrochemical systems, the results of which are reported here. The modular nature of fuel cells makes them ideal for creating geo-electrochemical reactors with which to simulate hydrothermal systems on wet rocky planets and characterize the energetic properties of the seafloor/hydrothermal interface. That electrochemical techniques should be applied to simulating the origin of life follows from the recognition of the fuel cell-like properties of prebiotic chemical systems and the earliest metabolisms. Conducting this type of laboratory simulation of the emergence of bioenergetics will not only be informative in the context of the origin of life on Earth but may help in understanding whether life might emerge in similar environments on other worlds.

Nanomaterial-Based Electrochemical Biosensors and Bioassays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Guodong; Mao, Xun; Gurung, Anant

2010-08-31

This book chapter summarizes the recent advance in nanomaterials for electrochemical biosensors and bioassays. Biofunctionalization of nanomaterials for biosensors fabrication and their biomedical applications are discussed.

Graphene-based electrochemical energy conversion and storage: fuel cells, supercapacitors and lithium ion batteries.

PubMed

Hou, Junbo; Shao, Yuyan; Ellis, Michael W; Moore, Robert B; Yi, Baolian

2011-09-14

Graphene has attracted extensive research interest due to its strictly 2-dimensional (2D) structure, which results in its unique electronic, thermal, mechanical, and chemical properties and potential technical applications. These remarkable characteristics of graphene, along with the inherent benefits of a carbon material, make it a promising candidate for application in electrochemical energy devices. This article reviews the methods of graphene preparation, introduces the unique electrochemical behavior of graphene, and summarizes the recent research and development on graphene-based fuel cells, supercapacitors and lithium ion batteries. In addition, promising areas are identified for the future development of graphene-based materials in electrochemical energy conversion and storage systems. This journal is © the Owner Societies 2011

Multilayered films of cobalt oxyhydroxide nanowires/manganese oxide nanosheets for electrochemical capacitor

NASA Astrophysics Data System (ADS)

Zheng, Huajun; Tang, Fengqiu; Lim, Melvin; Mukherji, Aniruddh; Yan, Xiaoxia; Wang, Lianzhou; (Max) Lu, Gao Qing

Multilayered films of cobalt oxyhydroxide nanowires (CoOOHNW) and exfoliated manganese oxide nanosheet (MONS) are fabricated by potentiostatic deposition and electrostatic self-assembly on indium-tin oxide coated glass substrates. The morphology and chemical composition of these films are characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS) and the potential application as electrochemical supercapacitors are investigated using cyclic voltammetry and charge-discharge measurements. These ITO/CoOOHNW/MONS multilayered film electrodes exhibit excellent electrochemical capacitance properties, including high specific capacitance (507 F g -1) and long cycling durability (less 2% capacity loss after 5000 charge/discharge cycles). These characteristics indicate that these newly developed films may find important application for electrochemical capacitors.

Ferrocene bound poly(vinyl chloride) as ion to electron transducer in electrochemical ion sensors.

PubMed

Pawlak, Marcin; Grygolowicz-Pawlak, Ewa; Bakker, Eric

2010-08-15

We report here on the synthesis of poly(vinyl chloride) (PVC) covalently modified with ferrocene groups (FcPVC) and the electrochemical behavior of the resulting polymeric membranes in view of designing all solid state voltammetric ion sensors. The Huisgen cycloaddition ("click chemistry") was found to be a simple and efficient method for ferrocene attachment. A degree of PVC modification with ferrocene groups between 1.9 and 6.1 mol % was achieved. The chemical modification of the PVC backbone does not significantly affect the ion-selective properties (selectivity, mobility, and solvent casting ability) of potentiometric sensing membranes applying this polymer. Importantly, the presence of such ferrocene groups may eliminate the need for an additional redox-active layer between the membrane and the inner electric contact in all solid state sensor designs. Electrochemical doping of this system was studied in a symmetrical sandwich configuration: glassy carbon electrode |FcPVC| glassy carbon electrode. Prior electrochemical doping from aqueous solution, resulting in a partial oxidation of the ferrocene groups, was confirmed to be necessary for the sandwich configuration to pass current effectively. The results suggest that only approximately 2.3 mol % of the ferrocene groups are electrochemically accessible, likely due to surface confined electrochemical behavior in the polymer. Indeed, cyclic voltammetry of aqueous hexacyanoferrate (III) remains featureless at cathodic potentials (down to -0.5 V). This indicates that the modified membrane is not responsive to redox-active species in the sample solution, making it possible to apply this polymer as a traditional, single membrane. Yet, the redox capacity of the electrode modified with this type of membrane was more than 520 microC considering a 20 mm(2) active electrode area, which appears to be sufficient for numerous practical ion voltammetric applications. The electrode was observed to operate reproducibly, with 1% standard deviation, when applying pulsed amperometric techniques.

Strategies for "wiring" redox-active proteins to electrodes and applications in biosensors, biofuel cells, and nanotechnology.

PubMed

Nöll, Tanja; Nöll, Gilbert

2011-07-01

In this tutorial review the basic approaches to establish electrochemical communication between redox-active proteins and electrodes are elucidated and examples for applications in electrochemical biosensors, biofuel cells and nanotechnology are presented. The early stage of protein electrochemistry is described giving a short overview over electron transfer (ET) between electrodes and proteins, followed by a brief introduction into experimental procedures for studying proteins at electrodes and possible applications arising thereof. The article starts with discussing the electrochemistry of cytochrome c, the first redox-active protein, for which direct reversible ET was obtained, under diffusion controlled conditions and after adsorption to electrodes. Next, examples for the electrochemical study of redox enzymes adsorbed on electrodes and modes of immobilization are discussed. Shortly the experimental approach for investigating redox-active proteins adsorbed on electrodes is outlined. Possible applications of redox enzymes in electrochemical biosensors and biofuel cells working by direct ET (DET) and mediated ET (MET) are presented. Furthermore, the reconstitution of redox active proteins at electrodes using molecular wire-like units in order to "wire" the proteins to the electrode surface and possible applications in nanotechnology are discussed.

Electrochemical hydrogen sulfide biosensors.

PubMed

Xu, Tailin; Scafa, Nikki; Xu, Li-Ping; Zhou, Shufeng; Abdullah Al-Ghanem, Khalid; Mahboob, Shahid; Fugetsu, Bunshi; Zhang, Xueji

2016-02-21

The measurement of sulfide, especially hydrogen sulfide, has held the attention of the analytical community due to its unique physiological and pathophysiological roles in biological systems. Electrochemical detection offers a rapid, highly sensitive, affordable, simple, and real-time technique to measure hydrogen sulfide concentration, which has been a well-documented and reliable method. This review details up-to-date research on the electrochemical detection of hydrogen sulfide (ion selective electrodes, polarographic hydrogen sulfide sensors, etc.) in biological samples for potential therapeutic use.

Model Based Optimal Control, Estimation, and Validation of Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Perez, Hector Eduardo

This dissertation focuses on developing and experimentally validating model based control techniques to enhance the operation of lithium ion batteries, safely. An overview of the contributions to address the challenges that arise are provided below. Chapter 1: This chapter provides an introduction to battery fundamentals, models, and control and estimation techniques. Additionally, it provides motivation for the contributions of this dissertation. Chapter 2: This chapter examines reference governor (RG) methods for satisfying state constraints in Li-ion batteries. Mathematically, these constraints are formulated from a first principles electrochemical model. Consequently, the constraints explicitly model specific degradation mechanisms, such as lithium plating, lithium depletion, and overheating. This contrasts with the present paradigm of limiting measured voltage, current, and/or temperature. The critical challenges, however, are that (i) the electrochemical states evolve according to a system of nonlinear partial differential equations, and (ii) the states are not physically measurable. Assuming available state and parameter estimates, this chapter develops RGs for electrochemical battery models. The results demonstrate how electrochemical model state information can be utilized to ensure safe operation, while simultaneously enhancing energy capacity, power, and charge speeds in Li-ion batteries. Chapter 3: Complex multi-partial differential equation (PDE) electrochemical battery models are characterized by parameters that are often difficult to measure or identify. This parametric uncertainty influences the state estimates of electrochemical model-based observers for applications such as state-of-charge (SOC) estimation. This chapter develops two sensitivity-based interval observers that map bounded parameter uncertainty to state estimation intervals, within the context of electrochemical PDE models and SOC estimation. Theoretically, this chapter extends the notion of interval observers to PDE models using a sensitivity-based approach. Practically, this chapter quantifies the sensitivity of battery state estimates to parameter variations, enabling robust battery management schemes. The effectiveness of the proposed sensitivity-based interval observers is verified via a numerical study for the range of uncertain parameters. Chapter 4: This chapter seeks to derive insight on battery charging control using electrochemistry models. Directly using full order complex multi-partial differential equation (PDE) electrochemical battery models is difficult and sometimes impossible to implement. This chapter develops an approach for obtaining optimal charge control schemes, while ensuring safety through constraint satisfaction. An optimal charge control problem is mathematically formulated via a coupled reduced order electrochemical-thermal model which conserves key electrochemical and thermal state information. The Legendre-Gauss-Radau (LGR) pseudo-spectral method with adaptive multi-mesh-interval collocation is employed to solve the resulting nonlinear multi-state optimal control problem. Minimum time charge protocols are analyzed in detail subject to solid and electrolyte phase concentration constraints, as well as temperature constraints. The optimization scheme is examined using different input current bounds, and an insight on battery design for fast charging is provided. Experimental results are provided to compare the tradeoffs between an electrochemical-thermal model based optimal charge protocol and a traditional charge protocol. Chapter 5: Fast and safe charging protocols are crucial for enhancing the practicality of batteries, especially for mobile applications such as smartphones and electric vehicles. This chapter proposes an innovative approach to devising optimally health-conscious fast-safe charge protocols. A multi-objective optimal control problem is mathematically formulated via a coupled electro-thermal-aging battery model, where electrical and aging sub-models depend upon the core temperature captured by a two-state thermal sub-model. The Legendre-Gauss-Radau (LGR) pseudo-spectral method with adaptive multi-mesh-interval collocation is employed to solve the resulting highly nonlinear six-state optimal control problem. Charge time and health degradation are therefore optimally traded off, subject to both electrical and thermal constraints. Minimum-time, minimum-aging, and balanced charge scenarios are examined in detail. Sensitivities to the upper voltage bound, ambient temperature, and cooling convection resistance are investigated as well. Experimental results are provided to compare the tradeoffs between a balanced and traditional charge protocol. Chapter 6: This chapter provides concluding remarks on the findings of this dissertation and a discussion of future work.

Kinetics of intercalation of lithium into NbSe3 and TiS2 cathodes

NASA Technical Reports Server (NTRS)

Ratnakumar, B. V.; Nagasubramanian, G.; Di Stefano, S.; Bankston, C. P.

1992-01-01

Titanium disulfide and niobium triselenide are two well-studied candidate materials for positive electrodes in rechargeable lithium cells. A comparative study of the kinetics of intercalation of lithium in both the cathodes is made here based on various electrochemical techniques, i.e., linear polarization, potentiodynamic polarization, and ac impedance under different experimental conditions such as prismatic or disk configuration of fresh, partially discharged, or cycled electrode. Further, the diffusion coefficients of lithium ions in these cathodes are estimated under these conditions using conventional techniques, i.e., ac impedance, chronocoulometry, chronoamperometry, and current pulse relaxation. Based on the values of the diffusion coefficients, the applicability of these methods for the determination of diffusion coefficients is discussed.

Recycling Titanium and Its Alloys by Utilizing Molten Salt

NASA Astrophysics Data System (ADS)

Okabe, Toru H.; Taninouchi, Yu-ki

It is commonly believed that the deoxidation of titanium (Ti), or the direct removal of oxygen (O) dissolved in metallic Ti, is practically impossible when magnesium (Mg) is used as the deoxidizing agent. In recent years, it has been experimentally demonstrated that O dissolved in Ti can be directly removed using MgCl2 molten salt electrolysis. By the electrochemical deoxidation technique, Ti wires containing 0.12 mass% O were deoxidized to less than 0.02 mass% O. In some cases, the concentration of O in the Ti wires was reduced to the level of 0.01 mass% O, which cannot be attained using the current Kroll process. The possible application of this deoxidation technique to practical industrial recycling processes is also discussed.

Design of an electrochemical prototype to determine relative NaCl content and its application in fresh cheeses

USDA-ARS?s Scientific Manuscript database

An electrochemical prototype (ECP) was designed and validated to determine NaCl electrical variables [volt (V), ampere (A), resistance (R), and power (P)] and its application for detection of possible adulteration in fresh cheeses. The ECP circuit consisted of two electrodes, aluminum (anode) and c...

Chemical modification of graphene aerogels for electrochemical capacitor applications.

PubMed

Hong, Jin-Yong; Wie, Jeong Jae; Xu, Yu; Park, Ho Seok

2015-12-14

Graphene aerogel is a relatively new type of aerogel that is ideal for energy storage applications because of its large surface area, high electrical conductivity and good chemical stability. Also, three dimensional interconnected macropores offer many advantages such as low density, fast ion and mass transfer, and easy access to storage sites. Such features allow graphene aerogels to be intensively applied for electrochemical capacitor applications. Despite the growing interest in graphene aerogel-based electrochemical capacitors, however, the graphene aerogels still suffer from their low capacitive performances and high fragility. Both relatively low capacitance and brittleness of physically crosslinked graphene aerogels remain a critical challenge. Until now, a number of alternative attempts have been devoted to overcome these shortcomings. In this perspective, we summarize the recent research progress towards the development of advanced graphene aerogel-based electrochemical capacitors according to the different approaches (e.g. porosity, composition and structure controls). Then, the recently proposed chemical strategies to improve the capacitive performances and mechanical durability of graphene aerogels for practical applications are highlighted. Finally, the current challenges and perspectives in this emerging material are also discussed.

The new age of carbon nanotubes: an updated review of functionalized carbon nanotubes in electrochemical sensors.

PubMed

Gao, Chao; Guo, Zheng; Liu, Jin-Huai; Huang, Xing-Jiu

2012-03-21

Since the discovery of carbon nanotubes (CNTs), they have drawn considerable research attention and have shown great potential application in many fields due to their unique structural, mechanical, and electronic properties. However, their native insolubility severely holds back the process of application. In order to overcome this disadvantage and broaden the scope of their application, chemical functionalization of CNTs has attracted great interest over the past several decades and produced various novel hybrid materials with specific applications. Notably, the rapid development of functionalized CNTs used as electrochemical sensors has been successfully witnessed. In this featured article, the recent progress of electrochemical sensors based on functionalized CNTs is discussed and classified according to modifiers covering organic (oxygen functional groups, small organic molecules, polymers, DNA, protein, etc.), inorganic (metal nanoparticles, metal oxide, etc.) and organic-inorganic hybrids. By employing some representative examples, it will be demonstrated that functionalized CNTs as templates, carriers, immobilizers and transducers are promising for the construction of electrochemical sensors. This journal is © The Royal Society of Chemistry 2012

Non-aqueous electrolytes for electrochemical cells

DOEpatents

Zhang, Zhengcheng; Dong, Jian; Amine, Khalil

2016-06-14

An electrolyte electrochemical device includes an anodic material and an electrolyte, the electrolyte including an organosilicon solvent, a salt, and a hybrid additiving having a first and a second compound, the hybrid additive configured to form a solid electrolyte interphase film on the anodic material upon application of a potential to the electrochemical device.

The Rise of Voltammetry: From Polarography to the Scanning Electrochemical Microscope

ERIC Educational Resources Information Center

Bard, Allen J.

2007-01-01

The drooping mercury electrode (DME) was previously used to carry out electrochemical experiments but invention of polarography technique changed this. Voltammetry with DME was given the term polarography and are used in measurement of current as a function of potential at small electrodes.

Nanostructured core-shell electrode materials for electrochemical capacitors

NASA Astrophysics Data System (ADS)

Jiang, Long-bo; Yuan, Xing-zhong; Liang, Jie; Zhang, Jin; Wang, Hou; Zeng, Guang-ming

2016-11-01

Core-shell nanostructure represents a unique system for applications in electrochemical energy storage devices. Owing to the unique characteristics featuring high power delivery and long-term cycling stability, electrochemical capacitors (ECs) have emerged as one of the most attractive electrochemical storage systems since they can complement or even replace batteries in the energy storage field, especially when high power delivery or uptake is needed. This review aims to summarize recent progress on core-shell nanostructures for advanced supercapacitor applications in view of their hierarchical architecture which not only create the desired hierarchical porous channels, but also possess higher electrical conductivity and better structural mechanical stability. The core-shell nanostructures include carbon/carbon, carbon/metal oxide, carbon/conducting polymer, metal oxide/metal oxide, metal oxide/conducting polymer, conducting polymer/conducting polymer, and even more complex ternary core-shell nanoparticles. The preparation strategies, electrochemical performances, and structural stabilities of core-shell materials for ECs are summarized. The relationship between core-shell nanostructure and electrochemical performance is discussed in detail. In addition, the challenges and new trends in core-shell nanomaterials development have also been proposed.

Preparation and characterization of green-nano-composite material based on polyaniline, multiwalled carbon nano tubes and carboxymethyl cellulose: For electrochemical sensor applications.

PubMed

Gautam, Vineeta; Singh, Karan Pratap; Yadav, Vijay Laxmi

2018-06-01

In this paper, we are presenting the preparation and characterization of "polyaniline/multiwalled carbon nanotubes/carboxymethyl cellulose" based novel composite material. It's morphological, thermal, structural, and electrochemical properties were investigated by using different instrumental techniques. During the in-situ chemical polymerization of aniline in the aqueous suspension of CMC and MWCNTs, the particle size change in two different ways "top to bottom" (low molecular weight oligomers grows in size) and "bottom to top" (long fibers of CMC fragmented in the reaction mixture). The combination of these two processes facilitated the fabrication of an integrated green-nano-composite material. In addition, a little amount of conductive nanofillers (MWCNTs) boosts the electrical and electrocatalytic properties of the material. Electron-rich centers of benzenoid rings exhibited π-π stacking with sp 2 carbon of MWCNTs. CMC dominantly impact on the properties of PANI, negatively charged carboxylate group of CMC ionically bonded with protonated amine/imine. FTIR and Raman analysis confirmed that the material has dominated quinoid units and effective charge transfer. Hydroxyl and carboxyl groups and bonded water molecules of CMC results in a network of hydrogen bonds (which induced directional property). PANI/MWCNTs/CMC have nanobead-like structures (TEM analysis), large surface area, large pore volume, small pore diameter (BET and BJH studies) and good dispersion ability in the aqueous phase. Nanostructures of aligned PANI exhibited excellent electrochemical properties have attracted increasing attention. Modified carbon paste electrode was used for electrocatalytic detection of ascorbic acid (as a model analyte). The sensor exhibited a linear range 0.05 mM-5 mM, sensitivity 100.63 μA mM -1  cm -2 , and limit of detection 0.01 mM. PANI/MWCNTs/CMC is suitable nanocomposite material for apply electroactive/conducting ink and membrane (which could be used in electrochemical sensor applications). Copyright © 2018 Elsevier Ltd. All rights reserved.

Salt-Assisted Ultrasonicated De-Aggregation and Advanced Redox Electrochemistry of Detonation Nanodiamond

PubMed Central

Gupta, Sanju; Evans, Brendan; Henson, Alex; Carrizosa, Sara B.

2017-01-01

Nanodiamond particles form agglomerates in the dry powder state and this poses limitation to the accessibility of their diamond-like core thus dramatically impacting their technological advancement. In this work, we report de-agglomeration of nanodiamond (ND) by using a facile technique namely, salt-assisted ultrasonic de-agglomeration (SAUD). Utilizing ultrasound energy and ionic salts (sodium chloride and sodium acetate), SAUD is expected to break apart thermally treated nanodiamond aggregates (~50–100 nm) and produce an aqueous slurry of de-aggregated stable colloidal nanodiamond dispersions by virtue of ionic interactions and electrostatic stabilization. Moreover, the SAUD technique neither has toxic chemicals nor is it difficult to remove impurities and therefore the isolated nanodiamonds produced are exceptionally suited for engineered nanocarbon for mechanical (composites, lubricants) and biomedical (bio-labeling, biosensing, bioimaging, theranostic) applications. We characterized the microscopic structure using complementary techniques including transmission electron microscopy combined with selected-area electron diffraction, optical and vibrational spectroscopy. We immobilized SAUD produced NDs on boron-doped diamond electrodes to investigate fundamental electrochemical properties. They included surface potential (or Fermi energy level), carrier density and mapping electrochemical (re)activity using advanced scanning electrochemical microscopy in the presence of a redox-active probe, with the aim of understanding the surface redox chemistry and the interfacial process of isolated nanodiamond particles as opposed to aggregated and untreated nanoparticles. The experimental findings are discussed in terms of stable colloids, quantum confinement and predominantly surface effects, defect sites (sp2–bonded C and unsaturated bonds), inner core (sp3–bonded C)/outer shell (sp2–bonded C) structure, and surface functionality. Moreover, the surface electronic states give rise to midgap states which serve as electron donors (or acceptors) depending upon the bonding (or antibonding). These are important as electroanalytical platforms for various electrocatalytic processes. PMID:29125547

Conducting polymers: Synthesis and industrial applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gottesfeld, S.

1997-04-01

The Conducting Polymer project funded by the AIM Program has developed new methods for the synthesis of conducting polymers and evaluated new industrial applications for these materials which will result in significant reductions in energy usage or industrial waste. The applications specifically addressed during FY 1996 included two ongoing efforts on membranes for gas separation and on electrochemical capacitors and a third new application: electrochemical reactors (ECRs) based on polymeric electrolytes. As a gas separation membrane, conducting polymers offer high selectivity and the potential to chemically or electrically adapt the membrane for specific gas combinations. Potential energy savings in themore » US for this application are estimated at 1 to 3 quads/yr. As an active material in electrochemical capacitors, electronically conducting polymers have the potential of storing large amounts of electric energy in low cost materials. Potential energy savings estimated at 1 quad/yr would result from introduction of electrochemical capacitors as energy storage devices in power trains of electric and hybrid vehicles, once such vehicles reach 20% of the total transportation market in the US. In the chlor-alkali industry, electrochemical reactors based on polymer electrolyte membranes consume around 1 % of the total electric power in the US. A new activity, started in FY 1996, is devoted to energy efficient ECRs. In the case of the chlor-alkali industry, energy savings as high as 50% seem possible with the novel ECR technology demonstrated by the author in 1996.« less

Electrochemical growth of SnS thin film: application to the photocatalytic degradation of rhodamine B under visible light

NASA Astrophysics Data System (ADS)

Kabouche, S.; Louafi, Y.; Bellal, B.; Trari, M.

2017-08-01

A facile and template-free wet electrochemical technique was used to deposit SnS on tin substrate. Longer time (>40 min) is required for the formation of the chalcogenide thin films and the potential must be carefully controlled to come out with a rough chemical identification of sulfide deposited at low potential scan. The deposition potential is selected from the cyclic voltammetry to preclude the oxidation of SnS to SnS2. The SnS films are uniform and well adhered to the substrate. They were characterized by X-ray diffraction, UV-Vis spectroscopy and electrochemical impedance spectroscopy (EIS). SnS crystallizes in an orthorhombic symmetry (SG: Pnma) and a crystallite size of 42 nm was obtained. The Mott-Schottky plot exhibited a linear behavior with a negative slope, characteristic of p-type conductivity. Holes density of 9.75 × 1020 cm-3, a flat band potential of 0.56 V SCE and a depletion width of 38 nm were determined. The valence band was located at (-5.41 eV/0.66 V) and derives mainly from S 2-: 3 p while the conduction band (3.8 eV/-0.95 V) was primarily made up of Sn2+: 5 p orbital. The EIS spectra measured over the frequency range (3 × 10-3-105 Hz) revealed mainly a bulk contribution. On application, rhodamine B was successfully oxidized on SnS films, 38% of the initial concentration (10 mg L-1) disappeared after 4 h of exposure to solar light (90 mW cm-2).

Metal-organic frameworks and their derived materials for electrochemical energy storage and conversion: Promises and challenges.

PubMed

Wu, Hao Bin; Lou, Xiong Wen David

2017-12-01

In addition to their conventional uses, metal-organic frameworks (MOFs) have recently emerged as an interesting class of functional materials and precursors of inorganic materials for electrochemical energy storage and conversion technologies. This class of MOF-related materials can be broadly categorized into two groups: pristine MOF-based materials and MOF-derived functional materials. Although the diversity in composition and structure leads to diverse and tunable functionalities of MOF-based materials, it appears that much more effort in this emerging field is devoted to synthesizing MOF-derived materials for electrochemical applications. This is in view of two main drawbacks of MOF-based materials: the low conductivity nature and the stability issue. On the contrary, MOF-derived synthesis strategies have substantial advantages in controlling the composition and structure of MOF-derived materials. From this perspective, we review some emerging applications of both groups of MOF-related materials as electrode materials for rechargeable batteries and electrochemical capacitors, efficient electrocatalysts, and even electrolytes for electrochemical devices. By highlighting the advantages and challenges of each class of materials for different applications, we hope to shed some light on the future development of this highly exciting area.

Metal-organic frameworks and their derived materials for electrochemical energy storage and conversion: Promises and challenges

PubMed Central

Wu, Hao Bin; Lou, Xiong Wen (David)

2017-01-01

In addition to their conventional uses, metal-organic frameworks (MOFs) have recently emerged as an interesting class of functional materials and precursors of inorganic materials for electrochemical energy storage and conversion technologies. This class of MOF-related materials can be broadly categorized into two groups: pristine MOF-based materials and MOF-derived functional materials. Although the diversity in composition and structure leads to diverse and tunable functionalities of MOF-based materials, it appears that much more effort in this emerging field is devoted to synthesizing MOF-derived materials for electrochemical applications. This is in view of two main drawbacks of MOF-based materials: the low conductivity nature and the stability issue. On the contrary, MOF-derived synthesis strategies have substantial advantages in controlling the composition and structure of MOF-derived materials. From this perspective, we review some emerging applications of both groups of MOF-related materials as electrode materials for rechargeable batteries and electrochemical capacitors, efficient electrocatalysts, and even electrolytes for electrochemical devices. By highlighting the advantages and challenges of each class of materials for different applications, we hope to shed some light on the future development of this highly exciting area. PMID:29214220

Evaluation of electrochemical, UV/VIS and Raman spectroelectrochemical detection of Naratriptan with screen-printed electrodes.

PubMed

Hernández, Carla Navarro; Martín-Yerga, Daniel; González-García, María Begoña; Hernández-Santos, David; Fanjul-Bolado, Pablo

2018-02-01

Naratriptan, active pharmaceutical ingredient with antimigraine activity was electrochemically detected in untreated screen-printed carbon electrodes (SPCEs). Cyclic voltammetry and differential pulse voltammetry were used to carry out quantitative analysis of this molecule (in a Britton-Robinson buffer solution at pH 3.0) through its irreversible oxidation (diffusion controlled) at a potential of +0.75V (vs. Ag pseudoreference electrode). Naratriptan oxidation product is an indole based dimer with a yellowish colour (maximum absorption at 320nm) so UV-VIS spectroelectrochemistry technique was used for the very first time as an in situ characterization and quantification technique for this molecule. A reflection configuration approach allowed its measurement over the untreated carbon based electrode. Finally, time resolved Raman Spectroelectrochemistry is used as a powerful technique to carry out qualitative and quantitative analysis of Naratriptan. Electrochemically treated silver screen-printed electrodes are shown as easy to use and cost-effective SERS substrates for the analysis of Naratriptan. Copyright © 2017 Elsevier B.V. All rights reserved.

Corrosion anisotropy of titanium deformed by the hydrostatic extrusion

NASA Astrophysics Data System (ADS)

Chojnacka, A.; Kawalko, J.; Koscielny, H.; Guspiel, J.; Drewienkiewicz, A.; Bieda, M.; Pachla, W.; Kulczyk, M.; Sztwiertnia, K.; Beltowska-Lehman, E.

2017-12-01

The corrosion behaviour of titanium rods deformed by hydrostatic extrusion (HE) in artificial saliva (Carter-Brugirard's solution of pH 7.6) was investigated using open-circuit potentials (OCPs), (DC) potentiodynamic polarisation curves and (AC) electrochemical impedance spectroscopy (EIS) techniques. Various electrochemical parameters (corrosion potential Ecorr, corrosion current (icorr), polarisation resistance Rp, charge transfer resistance Rct and oxide film resistance Rf) were analysed. Significant coherence was observed between results achieved from these procedures, i.e., all applied techniques showed the same trend for corrosion resistance. The obtained electrochemical data were then related to the microstructure parameters (crystallographic texture, grain size, grain boundary distribution and density) determined using the EBSD/SEM technique. It was found that the corrosion behaviour of titanium processed by the HE method was superior compared to the unprocessed Ti, and this was clearly dependent on the extrusion direction. The highest corrosion resistance was revealed for the HE-deformed Ti rod of the surface oriented longitudinal (parallel) to the extrusion direction.

Surface engineered porous silicon for stable, high performance electrochemical supercapacitors

PubMed Central

Oakes, Landon; Westover, Andrew; Mares, Jeremy W.; Chatterjee, Shahana; Erwin, William R.; Bardhan, Rizia; Weiss, Sharon M.; Pint, Cary L.

2013-01-01

Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10–40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage. PMID:24145684

Surface engineered porous silicon for stable, high performance electrochemical supercapacitors.

PubMed

Oakes, Landon; Westover, Andrew; Mares, Jeremy W; Chatterjee, Shahana; Erwin, William R; Bardhan, Rizia; Weiss, Sharon M; Pint, Cary L

2013-10-22

Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10-40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage.

Surface engineered porous silicon for stable, high performance electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Oakes, Landon; Westover, Andrew; Mares, Jeremy W.; Chatterjee, Shahana; Erwin, William R.; Bardhan, Rizia; Weiss, Sharon M.; Pint, Cary L.

2013-10-01

Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10-40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage.

Recent progress on the development of biofuel cells for self-powered electrochemical biosensing and logic biosensing: A review

DOE PAGES

Zhou, Ming

2015-06-12

Biofuel cells (BFCs) based on enzymes and microorganisms have been recently received considerable attention because they are recognized as an attractive type of energy conversion technology. In addition to the research activities related to the application of BFCs as power source, we have witnessed recently a growing interest in using BFCs for self-powered electrochemical biosensing and electrochemical logic biosensing applications. Compared with traditional biosensors, one of the most significant advantages of the BFCs-based self-powered electrochemical biosensors and logic biosensors is their ability to detect targets integrated with chemical-to-electrochemical energy transformation, thus obviating the requirement of external power sources. Following mymore » previous review (Electroanalysis 2012, 24, 197-209), the present review summarizes, discusses and updates the most recent progress and latest advances on the design and construction of BFCs-based self-powered electrochemical biosensors and logic biosensors. In addition to the traditional approaches based on substrate effect, inhibition effect, blocking effect and gene regulation effect for BFCs-based self-powered electrochemical biosensors and logic biosensors design, some new principles including enzyme effect, co-stabilization effect, competition effect and hybrid effect are summarized and discussed by me in details. The outlook and recommendation of future directions of BFCs-based self-powered electrochemical biosensors and logic biosensors are discussed in the end.« less

Unravelling the electrochemical double layer by direct probing of the solid/liquid interface

PubMed Central

Favaro, Marco; Jeong, Beomgyun; Ross, Philip N.; Yano, Junko; Hussain, Zahid; Liu, Zhi; Crumlin, Ethan J.

2016-01-01

The electrochemical double layer plays a critical role in electrochemical processes. Whilst there have been many theoretical models predicting structural and electrical organization of the electrochemical double layer, the experimental verification of these models has been challenging due to the limitations of available experimental techniques. The induced potential drop in the electrolyte has never been directly observed and verified experimentally, to the best of our knowledge. In this study, we report the direct probing of the potential drop as well as the potential of zero charge by means of ambient pressure X-ray photoelectron spectroscopy performed under polarization conditions. By analyzing the spectra of the solvent (water) and a spectator neutral molecule with numerical simulations of the electric field, we discern the shape of the electrochemical double layer profile. In addition, we determine how the electrochemical double layer changes as a function of both the electrolyte concentration and applied potential. PMID:27576762

Comparative study of the antioxidant capacity and polyphenol content of Douro wines by chemical and electrochemical methods.

PubMed

Rebelo, M J; Rego, R; Ferreira, M; Oliveira, M C

2013-11-01

A comparative study of the antioxidant capacity and polyphenols content of Douro wines by chemical (ABTS and Folin-Ciocalteau) and electrochemical methods (cyclic voltammetry and differential pulse voltammetry) was performed. A non-linear correlation between cyclic voltammetric results and ABTS or Folin-Ciocalteau data was obtained if all types of wines (white, muscatel, ruby, tawny and red wines) are grouped together in the same correlation plot. In contrast, a very good linear correlation was observed between the electrochemical antioxidant capacity determined by differential pulse voltammetry and the radical scavenging activity of ABTS. It was also found that the antioxidant capacity of wines evaluated by the electrochemical methods (expressed as gallic acid equivalents) depend on background electrolyte of the gallic acid standards, type of electrochemical signal (current or charge) and electrochemical technique. Copyright © 2013 Elsevier Ltd. All rights reserved.

Solid-state energy storage module employing integrated interconnect board

DOEpatents

Rouillard, Jean; Comte, Christophe; Daigle, Dominik; Hagen, Ronald A.; Knudson, Orlin B.; Morin, Andre; Ranger, Michel; Ross, Guy; Rouillard, Roger; St-Germain, Philippe; Sudano, Anthony; Turgeon, Thomas A.

2000-01-01

The present invention is directed to an improved electrochemical energy storage device. The electrochemical energy storage device includes a number of solid-state, thin-film electrochemical cells which are selectively interconnected in series or parallel through use of an integrated interconnect board. The interconnect board is typically disposed within a sealed housing which also houses the electrochemical cells, and includes a first contact and a second contact respectively coupled to first and second power terminals of the energy storage device. The interconnect board advantageously provides for selective series or parallel connectivity with the electrochemical cells, irrespective of electrochemical cell position within the housing. In one embodiment, a sheet of conductive material is processed by employing a known milling, stamping, or chemical etching technique to include a connection pattern which provides for flexible and selective interconnecting of individual electrochemical cells within the housing, which may be a hermetically sealed housing. Fuses and various electrical and electro-mechanical devices, such as bypass, equalization, and communication devices for example, may also be mounted to the interconnect board and selectively connected to the electrochemical cells.

Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

DOE PAGES

Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; ...

2014-10-22

Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were furthermore » correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. In conclusion, these studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses.« less

Metal current collect protected by oxide film

DOEpatents

Jacobson, Craig P.; Visco, Steven J.; DeJonghe, Lutgard C.

2004-05-25

Provided are low-cost, mechanically strong, highly electronically conductive current collects and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical devices having as current interconnects a ferritic steel felt or screen coated with a protective oxide film.

Electrochemical Study and Determination of Electroactive Species with Screen-Printed Electrodes

ERIC Educational Resources Information Center

Martín-Yerga, Daniel; Costa Rama, Estefanía; Costa García, Agustín

2016-01-01

A lab appropriate to introduce voltammetric techniques and basic electrochemical parameters is described in this work. It is suitable to study theoretical concepts of electrochemistry in an applied way for analytical undergraduate courses. Two electroactive species, hexaammineruthenium and dopamine, are used as simple redox systems. Screen-printed…

The Impedance Response of Semiconductors: An Electrochemical Engineering Perspective.

ERIC Educational Resources Information Center

Orazem, Mark E.

1990-01-01

Shows that the principles learned in the study of mass transport, thermodynamics, and kinetics associated with electrochemical systems can be applied to the transport and reaction processes taking place within a semiconductor. Describes impedance techniques and provides several graphs illustrating impedance data for diverse circuit systems. (YP)

Preparation and characterization of hierarchical porous carbons derived from solid leather waste for supercapacitor applications.

PubMed

Konikkara, Niketha; Kennedy, L John; Vijaya, J Judith

2016-11-15

Utilization of crust leather waste (CLW) as precursors for the preparation of hierarchical porous carbons (HPC) were investigated. HPCs were prepared from CLW by pre-carbonization followed by chemical activation using KOH at relatively high temperatures. Textural properties of HPC's showed an extent of micro-and mesoporosity with maximum BET surface area of 716m(2)/g. Inducements of graphitic planes in leather waste derived carbons were observed from X-ray diffraction and HR-TEM analysis. Microstructure, thermal behavior and surface functional groups were identified using FT-Raman, thermo gravimetric analysis and FT-IR techniques. HPCs were evaluated for electrochemical properties by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) by three electrode system. CLC9 sample showed a maximum capacitance of 1960F/g in 1M KCl electrolyte. Results achieved from rectangular curves of CV, GCD symmetric curves and Nyquist plots show that the leather waste carbon is suitable to fabricate supercapacitors as it possess high specific capacitance and electrochemical cycle stability. The present study proposes an effective method for solid waste management in leather industry by the way of converting toxic leather waste to new graphitic porous carbonaceous materials as a potential candidate for energy storage devices. Copyright © 2016 Elsevier B.V. All rights reserved.

Sensitive, selective, disposable electrochemical dopamine sensor based on PEDOT-modified laser scribed graphene.

PubMed

Xu, Guangyuan; Jarjes, Zahraa A; Desprez, Valentin; Kilmartin, Paul A; Travas-Sejdic, Jadranka

2018-06-01

The fabrication of a novel, and highly selective electrochemical sensor based on a poly(3,4-ethylenedioxythiophene) (PEDOT) modified laser scribed graphene (LSG), and detection of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA) is described. LSG electrodes were produced with a 3-dimensional macro-porous network and large electrochemically-active surface area via direct laser writing on polyimide sheets. PEDOT was electrodeposited on the LSG electrode, and the physical properties of the obtained films were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray diffraction microanalysis (EDAX). The modified electrodes were applied for the determination of DA in the presence of AA and UA using cyclic voltammetry (CV), and differential pulse voltammetry (DPV) techniques. The linear range for dopamine detection was found to be 1-150 µM with a sensitivity of 0.220 ± 0.011 µA μM -1 and a detection limit of 0.33 µM; superior values to those obtained without PEDOT. For the first time, PEDOT-modified LSG have been fabricated and assessed for high-performance dopamine sensing using cost-effective, disposable electrodes, with potential for development in further sensing applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation of Co3O4 conical nanotube and its application in calcium ion biosensor

NASA Astrophysics Data System (ADS)

Yuan, Hongwen; Ma, Chi; Geng, Junlong; Zhang, Liqiang; Cui, Hai; Liu, Cunzhi

2018-02-01

Calcium ion (Ca2+) is an important ion involved in body life activities, and its content detection in biomedical field owns great significance. In this study, we fabricated Co3O4 conical nanotube on F-doped tin oxide (FTO) substrate for detecting Ca2+. Co3O4 is fabricated through a hydrothermal method and demonstrates a regular hexagon structure, with a length of 5-10 μm and wall thickness of 30 nm. The structure and morphology of Co3O4 were characterized by X-ray diffraction (XRD), scanning electron microscope, and transmission electron microscopy, respectively. In addition, then, we used electrochemical technique to characterize the Ca2+ concentration in the simulated body fluid. The detection of Ca2+ is originated from the electrochemical reaction of hydrogen peroxide using Co3O4 as a catalyst, in which Ca2+ plays a significant role for accelerating the decomposition of hydrogen peroxide catalytic performance. By monitoring the electron transfer signals changes during the electrochemical reaction, we can quickly quantify the Ca2+ concentrations. It is found that this Ca2+ sensor owns a wide detection range (0.1-1.1 mM), a low detection limit (3.767 μM), and good anti-interference ability.

Hierarchical and Well-Ordered Porous Copper for Liquid Transport Properties Control.

PubMed

Pham, Quang N; Shao, Bowen; Kim, Yongsung; Won, Yoonjin

2018-05-09

Liquid delivery through interconnected pore network is essential for various interfacial transport applications ranging from energy storage to evaporative cooling. The liquid transport performance in porous media can be significantly improved through the use of hierarchical morphology that leverages transport phenomena at different length scales. Traditional surface engineering techniques using chemical or thermal reactions often show nonuniform surface nanostructuring within three-dimensional pore network due to uncontrollable diffusion and reactivity in geometrically complex porous structures. Here, we demonstrate hierarchical architectures on the basis of crystalline copper inverse opals using an electrochemistry approach, which offers volumetric controllability of structural and surface properties within the complex porous metal. The electrochemical process sequentially combines subtractive and additive steps-electrochemical polishing and electrochemical oxidation-to improve surface wetting properties without sacrificing structural permeability. We report the transport performance of the hierarchical inverse opals by measuring the capillary-driven liquid rise. The capillary performance parameter of hierarchically engineered inverse opal ( K/ R eff = ∼5 × 10 -3 μm) is shown to be higher than that of a typical crystalline inverse opal ( K/ R eff = ∼1 × 10 -3 μm) owing to the enhancement in fluid permeable and hydrophilic pathways. The new surface engineering method presented in this work provides a rational approach in designing hierarchical porous copper for transport performance enhancements.

Recent progress and developments in lithium cobalt phosphate chemistry- Syntheses, polymorphism and properties

NASA Astrophysics Data System (ADS)

Ludwig, Jennifer; Nilges, Tom

2018-04-01

This review summarizes the development, investigation, and optimization of polymorphic lithium cobalt phosphate LiCoPO4. One of the three polymorphs known to date, olivine-type or Pnma-LiCoPO4, shows intriguing electrochemical properties as a high-voltage cathode material, which are of interest for next-generation lithium-ion batteries with higher energy density. Hence, scientists have developed optimization strategies to improve its performance for commercial applications. Herein, a number of procedures for the synthesis of Pnma-LiCoPO4 is presented, including thermodynamic as well as kinetically controlled approaches. The continuous improvement of its electrochemical performance is illustrated, which was realized by the development of solvothermal techniques that allow a precise particle size and morphology control. In the course of these investigations, two new polymorphs, Pna21-LiCoPO4 and Cmcm-LiCoPO4, have been discovered which show different physical and structural properties compared to Pnma-LiCoPO4. Despite their significantly poorer electrochemical performance, these polymorphs allow interesting insights into the variable structure chemistry of transition-metal phosphates, which canalizes in intriguing magnetic and thermal properties. The similarities and differences in the chemical and physical properties of Pnma-LiCoPO4, Pna21-LiCoPO4, and Cmcm-LiCoPO4 are discussed.

Amplified electrochemiluminescence of quantum dots by electrochemically reduced graphene oxide for nanobiosensing of acetylcholine.

PubMed

Deng, Shengyuan; Lei, Jianping; Cheng, Lingxiao; Zhang, Yangyang; Ju, Huangxian

2011-07-15

A signal amplification system for electrochemiluminescence (ECL) of quantum dots (QDs) was developed by using electrochemically reduced graphene oxide (ERGO) to construct a nanobiosensing platform. Due to the structural defects of GO, the ECL emission of QDs coated on GO modified electrode was significantly quenched. After the electrochemical reduction of GO, the restoration of structural conjugation was observed with spectroscopic, morphologic and impedance techniques. Thus in the presence of dissolved O₂ as coreactant, the QDs/ERGO modified electrode showed ECL intensity increase by 4.2 and 178.9 times as compared with intrinsic QDs and QDs/GO modified electrodes due to the adsorption of dissolved O₂ on ERGO and the facilitated electron transfer. After choline oxidase (ChO) or ChO-acetylcholinesterase was further covalently cross-linked on the QDs/ERGO modified electrode, two ECL biosensors for choline and acetylcholine were fabricated, which showed the linear response ranges and detection limits of 10-210 μM and 8.8 μM for choline, and 10-250 μM and 4.7 μM for acetylcholine, respectively. This green and facile approach to prepare graphene-QDs system could be of potential applications in electronic device and bioanalysis. Copyright © 2011 Elsevier B.V. All rights reserved.

PH and Electrochemical Responsive Materials for Corrosion Smart Coating Applications

NASA Technical Reports Server (NTRS)

Li, Wenyan; Calle, Luz M.

2008-01-01

Corrosion is a costly issue for military operations and civil industries. While most corrosion initiates from localized corrosion form, such as pitting, failure directly caused by localized corrosion is the most dangerous kind, because it is difficult to anticipate and prevent, occurs very suddenly and can be catastrophic. One way of preventing these failures is with a coating that can detect and heal localized corrosion. pH and other electrochemical changes are often associated with localized corrosion, so it is expected that materials that are pH or otherwise electrochemical responsive can be used to detect and control corrosion. This paper will review various pH and electrochemical responsive materials and their potential applications in corrosion smart coatings. Current research results in this field will also be reported.

Polythiophene-carbon nanotubes composites as energy storage materials for supercapacitor application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thakur, A. K., E-mail: anukulphyism@gmail.com; Choudhary, R. B.; Sartale, S. D.

Polythiophene incorporated carbon materials have sought huge attention due to various improved electrochemical properties including enhanced electrical conductivity. Our work includes the synthesis of polythiophene (PTP)-multi-wallcarbon nanotubes (MWCNTs) via in-situ polymerization method. The homogeneous distribution of MWCNT in PTP was confirmed by Field Emission Scanning Electron Microscope (FESEM). Examination of the specimen using X-Ray diffraction (XRD), Fourier Transform-Infrared (FTIR) and Raman spectroscopy confirmed the composite formation. Other electrochemical characterizations like electrochemical impendence spectroscopy (EIS) and cyclic voltammetry (CV)of the PTP-MWCNT composite affirmed that incorporation of MWCNT improves the electrochemical properties of neat PTP including a significant increase in the capacitance.more » Hence making PTP-MWCNT isa better material for supercapacitor application than neat PTP.« less

Electrochemical Sensors for Clinic Analysis

PubMed Central

Wang, You; Xu, Hui; Zhang, Jianming; Li, Guang

2008-01-01

Demanded by modern medical diagnosis, advances in microfabrication technology have led to the development of fast, sensitive and selective electrochemical sensors for clinic analysis. This review addresses the principles behind electrochemical sensor design and fabrication, and introduces recent progress in the application of electrochemical sensors to analysis of clinical chemicals such as blood gases, electrolytes, metabolites, DNA and antibodies, including basic and applied research. Miniaturized commercial electrochemical biosensors will form the basis of inexpensive and easy to use devices for acquiring chemical information to bring sophisticated analytical capabilities to the non-specialist and general public alike in the future. PMID:27879810

Control of electro-chemical processes using energy harvesting materials and devices.

PubMed

Zhang, Yan; Xie, Mengying; Adamaki, Vana; Khanbareh, Hamideh; Bowen, Chris R

2017-12-11

Energy harvesting is a topic of intense interest that aims to convert ambient forms of energy such as mechanical motion, light and heat, which are otherwise wasted, into useful energy. In many cases the energy harvester or nanogenerator converts motion, heat or light into electrical energy, which is subsequently rectified and stored within capacitors for applications such as wireless and self-powered sensors or low-power electronics. This review covers the new and emerging area that aims to directly couple energy harvesting materials and devices with electro-chemical systems. The harvesting approaches to be covered include pyroelectric, piezoelectric, triboelectric, flexoelectric, thermoelectric and photovoltaic effects. These are used to influence a variety of electro-chemical systems such as applications related to water splitting, catalysis, corrosion protection, degradation of pollutants, disinfection of bacteria and material synthesis. Comparisons are made between the range harvesting approaches and the modes of operation are described. Future directions for the development of electro-chemical harvesting systems are highlighted and the potential for new applications and hybrid approaches are discussed.

Recent Progress in the Development of Conducting Polymer-Based Nanocomposites for Electrochemical Biosensors Applications: A Mini-Review.

PubMed

Naseri, Maryam; Fotouhi, Lida; Ehsani, Ali

2018-06-01

Among various immobilizing materials, conductive polymer-based nanocomposites have been widely applied to fabricate the biosensors, because of their outstanding properties such as excellent electrocatalytic activity, high conductivity, and strong adsorptive ability compared to conventional conductive polymers. Electrochemical biosensors have played a significant role in delivering the diagnostic information and therapy monitoring in a rapid, simple, and low cost portable device. This paper reviews the recent developments in conductive polymer-based nanocomposites and their applications in electrochemical biosensors. The article starts with a general and concise comparison between the properties of conducting polymers and conducting polymer nanocomposites. Next, the current applications of conductive polymer-based nanocomposites of some important conducting polymers such as PANI, PPy, and PEDOT in enzymatic and nonenzymatic electrochemical biosensors are overviewed. This review article covers an 8-year period beginning in 2010. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical production and use of free chlorine for pollutant removal: an experimental design approach.

PubMed

Antonelli, Raissa; de Araújo, Karla Santos; Pires, Ricardo Francisco; Fornazari, Ana Luiza de Toledo; Granato, Ana Claudia; Malpass, Geoffroy Roger Pointer

2017-10-28

The present paper presents the study of (1) the optimization of electrochemical-free chlorine production using an experimental design approach, and (2) the application of the optimum conditions obtained for the application in photo-assisted electrochemical degradation of simulated textile effluent. In the experimental design the influence of inter-electrode gap, pH, NaCl concentration and current was considered. It was observed that the four variables studied are significant for the process, with NaCl concentration and current being the most significant variables for free chlorine production. The maximum free chlorine production was obtained at a current of 2.33 A and NaCl concentrations in 0.96 mol dm -3 . The application of the optimized conditions with simultaneous UV irradiation resulted in up to 83.1% Total Organic Carbon removal and 100% of colour removal over 180 min of electrolysis. The results indicate that a systematic (statistical) approach to the electrochemical treatment of pollutants can save time and reagents.

Manganese oxide-based materials as electrochemical supercapacitor electrodes.

PubMed

Wei, Weifeng; Cui, Xinwei; Chen, Weixing; Ivey, Douglas G

2011-03-01

Electrochemical supercapacitors (ECs), characteristic of high power and reasonably high energy densities, have become a versatile solution to various emerging energy applications. This critical review describes some materials science aspects on manganese oxide-based materials for these applications, primarily including the strategic design and fabrication of these electrode materials. Nanostructurization, chemical modification and incorporation with high surface area, conductive nanoarchitectures are the three major strategies in the development of high-performance manganese oxide-based electrodes for EC applications. Numerous works reviewed herein have shown enhanced electrochemical performance in the manganese oxide-based electrode materials. However, many fundamental questions remain unanswered, particularly with respect to characterization and understanding of electron transfer and atomic transport of the electrochemical interface processes within the manganese oxide-based electrodes. In order to fully exploit the potential of manganese oxide-based electrode materials, an unambiguous appreciation of these basic questions and optimization of synthesis parameters and material properties are critical for the further development of EC devices (233 references).

Electrochemical Impedance Of Inorganic-Zinc-Coated Steel

NASA Technical Reports Server (NTRS)

Macdowell, Louis G.

1992-01-01

Report describes preliminary experiments to evaluate both direct-current and alternating-current electrochemical impedance measurements as candidate techniques for use in accelerated corrosion testing of mild-steel panels coated with inorganic zinc-rich primers and exposed to seaside air. Basic idea behind experiments to compare electrochemical impedance measurements with anticorrosion performances of coating materials to determine whether measurements can be used to predict performances. Part of continuing program to identify anticorrosion coating materials protecting steel panels adequately for as long as 5 years and beyond.

Characterization of pi-Conjugated Polymers for Transistor and Photovoltaic Applications

NASA Astrophysics Data System (ADS)

Paulsen, Bryan D.

pi-Conjugated polymers represent a unique class of optoelectronic materials. Being polymers, they are solution processable and inherently "soft" materials. This makes them attractive candidates for the production of roll-to-roll printed electronic devices on flexible substrates. The optical and electronic properties of pi-conjugated polymers are synthetically tunable allowing material sets to be tailored to specific applications. Two of the most heavily researched applications are the thin film transistor, the building block of electronic circuits, and the bulk heterojunction solar cell, which holds great potential as a renewable energy source. Key to developing commercially feasible pi-conjugated polymer devices is a thorough understanding of the electronic structure and charge transport behavior of these materials in relationship with polymer structure. Here this structure property relationship has been investigated through electrical and electrochemical means in concert with a variety of other characterization techniques and device test beds. The tunability of polymer optical band gap and frontier molecular orbital energy level was investigated in systems of vinyl incorporating statistical copolymers. Energy levels and band gaps are crucial parameters in developing efficient photovoltaic devices, with control of these parameters being highly desirable. Additionally, charge transport and density of electronic states were investigated in pi-conjugated polymers at extremely high electrochemically induced charge density. Finally, the effects of molecular weight on pi-conjugated polymer optical properties, energy levels, charge transport, morphology, and photovoltaic device performance was examined.

Mesoporous silicon oxide films and their uses as templates in obtaining nanostructured conductive polymers

NASA Astrophysics Data System (ADS)

Salgado, R.; Arteaga, G. C.; Arias, J. M.

2018-04-01

Obtaining conductive polymers (CPs) for the manufacture of OLEDs, solar cells, electrochromic devices, sensors, etc., has been possible through the use of electrochemical techniques that allow obtaining films of controlled thickness with positive results in different applications. Current trends point towards the manufacture of nanomaterials, and therefore it is necessary to develop methods that allow obtaining CPs with nanostructured morphology. This is possible by using a porous template to allow the growth of the polymeric materials. However, prior and subsequent treatments are required to separate the material from the template so that it can be evaluated in the applications mentioned above. This is why mesoporous silicon oxide films (template) are essential for the synthesis of nanostructured polymers since both the template and the polymer are obtained on the electrode surface, and therefore it is not necessary to separate the material from the template. Thus, the material can be evaluated directly in the applications mentioned above. The dimensions of the resulting nanostructures will depend on the power, time and technique used for electropolymerization as well as the monomer and the surfactant of the mesoporous film.

On-site applicability of hydrogen peroxide producing microbial electrochemical cells (MECs) coupled with UV in wastewater disinfection study

EPA Science Inventory

Background: There is an increased interest in the application of microbial electrochemical cell (MEC) for the recovery of value-added products such as hydrogen gas and hydrogen peroxide (H2O2) from wastewater. H2O2 has strong oxidation capability and produces hydroxyl radicals wh...