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.

Multi-dimensional construction of a novel active yolk@conductive shell nanofiber web as a self-standing anode for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Liu, Hao; Chen, Luyi; Liang, Yeru; Fu, Ruowen; Wu, Dingcai

2015-11-01

A novel active yolk@conductive shell nanofiber web with a unique synergistic advantage of various hierarchical nanodimensional objects including the 0D monodisperse SiO2 yolks, the 1D continuous carbon shell and the 3D interconnected non-woven fabric web has been developed by an innovative multi-dimensional construction method, and thus demonstrates excellent electrochemical properties as a self-standing LIB anode.A novel active yolk@conductive shell nanofiber web with a unique synergistic advantage of various hierarchical nanodimensional objects including the 0D monodisperse SiO2 yolks, the 1D continuous carbon shell and the 3D interconnected non-woven fabric web has been developed by an innovative multi-dimensional construction method, and thus demonstrates excellent electrochemical properties as a self-standing LIB anode. Electronic supplementary information (ESI) available: Experimental details and additional information about material characterization. See DOI: 10.1039/c5nr06531c

Graphene electrochemistry: an overview of potential applications.

PubMed

Brownson, Dale A C; Banks, Craig E

2010-11-01

Graphene, a 2D nanomaterial that possesses spectacular physical, chemical and thermal properties, has caused immense excitement amongst scientists since its freestanding form was isolated in 2004. With research into graphene rife, it promises enhancements and vast applicability within many industrial aspects. Furthermore, graphene possesses a vast array of unique and highly desirable electrochemical properties, and it is this application that offers the most enthralling and spectacular journey. We present a review of the current literature concerning the electrochemical applications and advancements of graphene, starting with its use as a sensor substrate through to applications in energy production and storage, depicting the truly remarkable journey of a material that has just come of age.

Electrochemical sensors and biosensors based on less aggregated graphene.

PubMed

Bo, Xiangjie; Zhou, Ming; Guo, Liping

2017-03-15

As a novel single-atom-thick sheet of sp 2 hybridized carbon atoms, graphene (GR) has attracted extensive attention in recent years because of its unique and remarkable properties, such as excellent electrical conductivity, large theoretical specific surface area, and strong mechanical strength. However, due to the π-π interaction, GR sheets are inclined to stack together, which may seriously degrade the performance of GR with the unique single-atom layer. In recent years, an increasing number of GR-based electrochemical sensors and biosensors are reported, which may reflect that GR has been considered as a kind of hot and promising electrode material for electrochemical sensor and biosensor construction. However, the active sites on GR surface induced by the irreversible GR aggregations would be deeply secluded inside the stacked GR sheets and therefore are not available for the electrocatalysis. So the alleviation or the minimization of the aggregation level for GR sheets would facilitate the exposure of active sites on GR and effectively upgrade the performance of GR-based electrochemical sensors and biosensors. Less aggregated GR with low aggregation and high dispersed structure can be used in improving the electrochemical activity of GR-based electrochemical sensors or biosensors. In this review, we summarize recent advances and new progress for the development of electrochemical sensors based on less aggregated GR. To achieve such goal, many strategies (such as the intercalation of carbon materials, surface modification, and structural engineering) have been applied to alleviate the aggregation level of GR in order to enhance the performance of GR-based electrochemical sensors and biosensors. Finally, the challenges associated with less aggregated GR-based electrochemical sensors and biosensors as well as related future research directions are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

The electrochemical Evaluation of a Zr-Based Bulk Metallic Glass in a Phosphate-Buffered Saline Electrolyte

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

Morrison, M. L.; Buchanan, R. A.; Leon, R. V.

2005-01-01

Bulk metallic glasses (BMGs) represent an emerging class of materials with an amorphous structure and a unique combination of properties. The objectives of this investigation were to define the electrochemical behavior of a specific Zr-based BMG alloy in a physiologically relevant environment and to compare these properties to standard, crystalline biomaterials as well as other Zr-based BMG compositions. Cyclic-anodic-polarization studies were conducted with a Zr{sub 52.5}Cu{sub 17.9}Ni{sub 14.6}Al{sub 10.0}Ti{sub 5.0} (at %) BMG in a phosphate-buffered saline electrolyte with a physiologically relevant oxygen content at 37 C. The results were compared to three common, crystalline biomaterials: CoCrMo, 316L stainless steel,more » and Ti-6Al-4V. The BMG alloy was found to have a lower corrosion penetration rate (CPR), as compared to the 316L stainless steel, and an equivalent CPR, as compared to the CoCrMo and Ti-6Al-4V alloys. Furthermore, the BMG alloy demonstrated better localized corrosion resistance than the 316L stainless steel. However, the localized corrosion resistance of the BMG alloy was not as high as those of the CoCrMo and Ti-6Al-4V alloys in the tested environment. The excellent electrochemical properties demonstrated by the BMG alloy are combined with a low modulus and unparalleled strength. This unique combination of properties dramatically demonstrates the potential for amorphous alloys as a new generation of biomaterials.« less

In Situ Electrochemical Sensing and Real-Time Monitoring Live Cells Based on Freestanding Nanohybrid Paper Electrode Assembled from 3D Functionalized Graphene Framework.

PubMed

Zhang, Yan; Xiao, Jian; Lv, Qiying; Wang, Lu; Dong, Xulin; Asif, Muhammad; Ren, Jinghua; He, Wenshan; Sun, Yimin; Xiao, Fei; Wang, Shuai

2017-11-08

In this work, we develop a new type of freestanding nanohybrid paper electrode assembled from 3D ionic liquid (IL) functionalized graphene framework (GF) decorated by gold nanoflowers (AuNFs), and explore its practical application in in situ electrochemical sensing of live breast cell samples by real-time tracking biomarker H 2 O 2 released from cells. The AuNFs modified IL functionalized GF (AuNFs/IL-GF) was synthesized via a facile and efficient dopamine-assisted one-pot self-assembly strategy. The as-obtained nanohybrid assembly exhibits a typical 3D hierarchical porous structure, where the highly active electrocatalyst AuNFs are well dispersed on IL-GF scaffold. And the graft of hydrophilic IL molecules (i.e., 1-butyl-3-methylimidazolium tetrafluoroborate, BMIMBF 4 ) on graphene nanosheets not only avoids their agglomeration and disorder stacking during the self-assembly but also endows the integrated IL-GF monolithic material with unique hydrophilic properties, which enables it to be readily dispersed in aqueous solution and processed into freestanding paperlike material. Because of the unique structural properties and the combinational advantages of different components in the AuNFs/IL-GF composite, the resultant nanohybrid paper electrode exhibits good nonenzymatic electrochemical sensing performance toward H 2 O 2 . When used in real-time tracking H 2 O 2 secreted from different breast cells attached to the paper electrode without or with radiotherapy treatment, the proposed electrochemical sensor based on freestanding AuNFs/IL-GF paper electrode can distinguish the normal breast cell HBL-100 from the cancer breast cells MDA-MB-231 and MCF-7 cells, and assess the radiotherapy effects to different breast cancer cells, which opens a new horizon in real-time monitoring cancer cells by electrochemical sensing platform.

Electrochromic WO[subscript 3] Films: Nanotechnology Experiments in Instrumental Analysis and Physical Chemistry Laboratories

ERIC Educational Resources Information Center

Hepel, Maria

2008-01-01

This experiment teaches students the methodology of investigating novel properties of materials using new instrumental techniques: atomic force microscopy (AFM), electrochemical quartz crystal nanobalance (EQCN), voltammetric techniques (linear potential scan and chronoamperometry), and light reflectance measurements. The unique capabilities of…

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.

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.

Electrochemical sensing of heavy metal ions with inorganic, organic and bio-materials.

PubMed

Cui, Lin; Wu, Jie; Ju, Huangxian

2015-01-15

As heavy metal ions severely harm human health, it is important to develop simple, sensitive and accurate methods for their detection in environment and food. Electrochemical detection featured with short analytical time, low power cost, high sensitivity and easy adaptability for in-situ measurement is one of the most developed methods. This review introduces briefly the recent achievements in electrochemical sensing of heavy metal ions with inorganic, organic and bio-materials modified electrodes. In particular, the unique properties of inorganic nanomaterials, organic small molecules or their polymers, enzymes and nucleic acids for detection of heavy metal ions are highlighted. By employing some representative examples, the design and sensing mechanisms of these electrodes are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Graphene-Selenium Hybrid Microballs as Cathode Materials for High-performance Lithium-Selenium Secondary Battery Applications.

PubMed

Youn, Hee-Chang; Jeong, Jun Hui; Roh, Kwang Chul; Kim, Kwang-Bum

2016-08-02

In this study, graphene-selenium hybrid microballs (G-SeHMs) are prepared in one step by aerosol microdroplet drying using a commercial spray dryer, which represents a simple, scalable continuous process, and the potential of the G-SeHMs thus prepared is investigated for use as cathode material in applications of lithium-selenium secondary batteries. These morphologically unique graphene microballs filled with Se particles exhibited good electrochemical properties, such as high initial specific capacity (642 mA h g(-1) at 0.1 C, corresponding to Se electrochemical utilisation as high as 95.1%), good cycling stability (544 mA h g(-1) after 100 cycles at 0.1 C; 84.5% retention) and high rate capability (specific capacity of 301 mA h g(-1) at 5 C). These electrochemical properties are attributed to the fact that the G-SeHM structure acts as a confinement matrix for suppressing the dissolution of polyselenides in the organic electrolyte, as well as an electron conduction path for increasing the transport rate of electrons for electrochemical reactions. Notably, based on the weight of hybrid materials, electrochemical performance is considerably better than that of previously reported Se-based cathode materials, attributed to the high Se loading content (80 wt%) in hybrid materials.

Electrochemical growth of linear conducting crystals in microgravity

NASA Technical Reports Server (NTRS)

Cronise, Raymond J., IV

1988-01-01

Much attention has been given to the synthesis of linear conducting materials. These inorganic, organic, and polymeric materials have some very interesting electrical and optical properties, including low temperature superconductivity. Because of the anisotropic nature of these compounds, impurities and defects strongly influences the unique physical properties of such crystals. Investigations have demonstrated that electrochemical growth has provided the most reproducible and purest crystals. Space, specifically microgravity, eliminates phenomena such as buoyancy driven convection, and could permit formation of crystals many times purer than the ones grown to date. Several different linear conductors were flown on Get Away Special G-007 on board the Space Shuttle Columbia, STS 61-C, the first of a series of Project Explorer payloads. These compounds were grown by electrochemical methods, and the growth was monitored by photographs taken throughout the mission. Due to some thermal problems, no crystals of appreciable size were grown. The experimental results will be incorporated into improvements for the next 2 missions of Project Explorer. The results and conclusions of the first mission are discussed.

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

Label-free immunosensor based on Pd nanoplates for amperometric immunoassay of alpha-fetoprotein.

PubMed

Wang, Huan; Li, He; Zhang, Yihe; Wei, Qin; Ma, Hongmin; Wu, Dan; Li, Yan; Zhang, Yong; Du, Bin

2014-03-15

In this paper, Pd nanoplates were used as a kind of electrode materials for fabrication of an electrochemical immunosensor, which was applied for detection of cancer biomarker alpha-fetoprotein (AFP). Thanks to the unique structure and properties of Pd nanoplates, the antibody of AFP (Ab) was effectively immobilized onto the surface of the Pd nanoplates modified glassy carbon electrode (GCE). Moreover, the good electrochemical properties of Pd nanoplates greatly improved the electronic transmission rate and enhanced the electrochemical signal, which led to an increase of the detection sensitivity. Based on the specific antibody-antigen interaction, a label-free immunosensor based on Pd nanoplates was developed for sensing of AFP. The current method allows us to detect AFP over a wide concentration range from 0.01 to 75.0 ng/mL with a detection limit of 4 pg/mL. The proposed immunosensor has been used to determine AFP in human serum with satisfactory results. © 2013 Elsevier B.V. All rights reserved.

Three-Dimensional Architectures Constructed from Transition-Metal Dichalcogenide Nanomaterials for Electrochemical Energy Storage and Conversion.

PubMed

Yun, Qinbai; Lu, Qipeng; Zhang, Xiao; Tan, Chaoliang; Zhang, Hua

2018-01-15

Transition-metal dichalcogenides (TMDs) have attracted considerable attention in recent years because of their unique properties and promising applications in electrochemical energy storage and conversion. However, the limited number of active sites as well as blocked ion and mass transport severely impair their electrochemical performance. The construction of three-dimensional (3D) architectures from TMD nanomaterials has been proven to be an effective strategy to solve the aforementioned problems as a result of their large specific surface areas and short ion and mass transport distances. This Review summarizes the commonly used routes to build 3D TMD architectures and highlights their applications in electrochemical energy storage and conversion, including batteries, supercapacitors, and electrocatalytic hydrogen evolution. The challenges and outlook in this research area are also discussed. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The edge- and basal-plane-specific electrochemistry of a single-layer graphene sheet

PubMed Central

Yuan, Wenjing; Zhou, Yu; Li, Yingru; Li, Chun; Peng, Hailin; Zhang, Jin; Liu, Zhongfan; Dai, Liming; Shi, Gaoquan

2013-01-01

Graphene has a unique atom-thick two-dimensional structure and excellent properties, making it attractive for a variety of electrochemical applications, including electrosynthesis, electrochemical sensors or electrocatalysis, and energy conversion and storage. However, the electrochemistry of single-layer graphene has not yet been well understood, possibly due to the technical difficulties in handling individual graphene sheet. Here, we report the electrochemical behavior at single-layer graphene-based electrodes, comparing the basal plane of graphene to its edge. The graphene edge showed 4 orders of magnitude higher specific capacitance, much faster electron transfer rate and stronger electrocatalytic activity than those of graphene basal plane. A convergent diffusion effect was observed at the sub-nanometer thick graphene edge-electrode to accelerate the electrochemical reactions. Coupling with the high conductivity of a high-quality graphene basal plane, graphene edge is an ideal electrode for electrocatalysis and for the storage of capacitive charges. PMID:23896697

The electrophotonic silicon biosensor

NASA Astrophysics Data System (ADS)

Juan-Colás, José; Parkin, Alison; Dunn, Katherine E.; Scullion, Mark G.; Krauss, Thomas F.; Johnson, Steven D.

2016-09-01

The emergence of personalized and stratified medicine requires label-free, low-cost diagnostic technology capable of monitoring multiple disease biomarkers in parallel. Silicon photonic biosensors combine high-sensitivity analysis with scalable, low-cost manufacturing, but they tend to measure only a single biomarker and provide no information about their (bio)chemical activity. Here we introduce an electrochemical silicon photonic sensor capable of highly sensitive and multiparameter profiling of biomarkers. Our electrophotonic technology consists of microring resonators optimally n-doped to support high Q resonances alongside electrochemical processes in situ. The inclusion of electrochemical control enables site-selective immobilization of different biomolecules on individual microrings within a sensor array. The combination of photonic and electrochemical characterization also provides additional quantitative information and unique insight into chemical reactivity that is unavailable with photonic detection alone. By exploiting both the photonic and the electrical properties of silicon, the sensor opens new modalities for sensing on the microscale.

Graphene Based Electrochemical Sensors and Biosensors: A Review

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

Shao, Yuyan; Wang, Jun; Wu, Hong

2010-05-01

Graphene, emerging as a true 2-dimensional material, has received increasing attention due to its unique physicochemical properties (high surface area, excellent conductivity, high mechanical strength, and ease of functionalization and mass production). This article selectively reviews recent advances in graphene-based electrochemical sensors and biosensors. In particular, graphene for direct electrochemistry of enzyme, its electrocatalytic activity toward small biomolecules (hydrogen peroxide, NADH, dopamine, etc.), and graphene-based enzyme biosensors have been summarized in more detail; Graphene-based DNA sensing and environmental analysis have been discussed. Future perspectives in this rapidly developing field are also discussed.

Electrochemical and optical biosensors based on nanomaterials and nanostructures: a review.

PubMed

Li, Ming; Li, Rui; Li, Chang Ming; Wu, Nianqiang

2011-06-01

Nanomaterials and nanostructures exhibit unique size-tunable and shape-dependent physicochemical properties that are different from those of bulk materials. Advances of nanomaterials and nanostructures open a new door to develop various novel biosensors. The present work has reviewed the recent progress in electrochemical, surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS) and fluorescent biosensors based on nanomaterials and nanostructures. An emphasis is put on the research that demonstrates how the performance of biosensors such as the limit of detection, sensitivity and selectivity is improved by the use of nanomaterials and nanostructures.

Porous silicon platform for optical detection of functionalized magnetic particles biosensing.

PubMed

Ko, Pil Ju; Ishikawa, Ryousuke; Sohn, Honglae; Sandhu, Adarsh

2013-04-01

The physical properties of porous materials are being exploited for a wide range of applications including optical biosensors, waveguides, gas sensors, micro capacitors, and solar cells. Here, we review the fast, easy and inexpensive electrochemical anodization based fabrication porous silicon (PSi) for optical biosensing using functionalized magnetic particles. Combining magnetically labeled biomolecules with PSi offers a rapid and one-step immunoassay and real-time detection by magnetic manipulation of superparamagnetic beads (SPBs) functionalized with target molecules onto corresponding probe molecules immobilized inside nano-pores of PSi. We first give an introduction to electrochemical and chemical etching procedures used to fabricate a wide range of PSi structures. Next, we describe the basic properties of PSi and underlying optical scattering mechanisms that govern their unique optical properties. Finally, we give examples of our experiments that demonstrate the potential of combining PSi and magnetic beads for real-time point of care diagnostics.

Improved electrochemical properties of morphology-controlled titania/titanate nanostructures prepared by in-situ hydrothermal surface modification of self-source Ti substrate for high-performance supercapacitors.

PubMed

Banerjee, Arghya Narayan; Anitha, V C; Joo, Sang W

2017-10-16

Ti substrate surface is modified into two-dimensional (2D) TiO 2 nanoplatelet or one-dimensional (1D) nanorod/nanofiber (or a mixture of both) structure in a controlled manner via a simple KOH-based hydrothermal technique. Depending on the KOH concentration, different types of TiO 2 nanostructures (2D platelets, 1D nanorods/nanofibers and a 2D+1D mixed sample) are fabricated directly onto the Ti substrate surface. The novelty of this technique is the in-situ modification of the self-source Ti surface into titania nanostructures, and its direct use as the electrochemical microelectrode without any modifications. This leads to considerable improvement in the interfacial properties between metallic Ti and semiconducting TiO 2 . Since interfacial states/defects have profound effect on charge transport properties of electronic/electrochemical devices, therefore this near-defect-free interfacial property of Ti-TiO 2 microelectrode has shown high supercapacitive performances for superior charge-storage devices. Additionally, by hydrothermally tuning the morphology of titania nanostructures, the electrochemical properties of the electrodes are also tuned. A Ti-TiO 2 electrode comprising of a mixture of 2D-platelet+1D-nanorod structure reveals very high specific capacitance values (~7.4 mF.cm -2 ) due to the unique mixed morphology which manifests higher active sites (hence, higher utilization of the active materials) in terms of greater roughness at the 2D-platelet structures and higher surface-to-volume-ratio in the 1D-nanorod structures.

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.

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

A graphene-based electrochemical sensor for sensitive detection of paracetamol

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

Kang, Xinhuang; Wang, Jun; Wu, Hong

2010-05-15

An electrochemical sensor based on the electrocatalytic activity of functionalized graphene for sensitive detection of paracetamol is presented. The electrochemical behaviors of paracetamol on graphene-modified glassy carbon electrodes (GCEs) were investigated by cyclic voltammetry and square-wave voltammetry. The results showed that the graphene-modified electrode exhibited excellent electrocatalytic activity to paracetamol. A quasi-reversible redox process of paracetamol at the modified electrode was obtained, and the over-potential of paracetamol decreased significantly compared with that at the bare GCE. Such electrocatalytic behavior of graphene is attributed to its unique physical and chemical properties, e.g., subtle electronic characteristics, attractive π–π interaction, and strong adsorptivemore » capability. The sensor shows great promise for simple, sensitive, and quantitative detection of paracetamol.« less

Development of a reinforced electrochemically aligned collagen bioscaffold for tendon tissue engineering applications

NASA Astrophysics Data System (ADS)

Uquillas Paredes, Jorge Alfredo

Type-I collagen is a promising biomaterial that can be used to synthesize bioscaffolds as a strategy to regenerate and repair damaged tendons. The existing in vitro prepared collagen bioscaffolds are in the form of gels, foams, or extruded fibers. These bioscaffolds readily present sites for attachment of biological factors and cells; however, they have extremely poor biomechanical properties in comparison to the properties of native tendons. The biomechanical function of type-I collagen bioscaffolds needs to be elevated to the level of natural tissues for this biomaterial to replace mechanically challenged tendons in a functionally meaningful way. The overall goal of this dissertation is to develop a reinforced electrochemically aligned collagenous bioscaffold for applications in tendon tissue engineering. The bioscaffold is synthesized by a unique electrochemical process via isoelectric focusing (IEF) to attain a very high degree of molecular alignment and packing density. This dissertation presents progress made on four aims: A) development of simple and descriptive electrochemical theory via the mathematical model of IEF and the forces acting on collagen alignment under an electric field; B) optimization of the post-alignment PBS treatment step to achieve d- banding pattern in uncrosslinked electrochemically aligned collagen (ELAC) bioscaffolds; C) optimization of the best crosslinking protocol to produce the strongest possible ELAC biomaterial with excellent cellular compatibility; and D) in vivo evaluation of the biocompatibility and biodegradability properties of electronically aligned collagen bioscaffolds. The results of this dissertation provide strong evidence showing that reinforced ELAC bioscaffolds could be used clinically in the future to repair damaged tendons.

Bioinspired peptide nanotubes: deposition technology, basic physics and nanotechnology applications.

PubMed

Rosenman, G; Beker, P; Koren, I; Yevnin, M; Bank-Srour, B; Mishina, E; Semin, S

2011-02-01

Synthetic peptide monomers can self-assemble into PNM such as nanotubes, nanospheres, hydrogels, etc. which represent a novel class of nanomaterials. Molecular recognition processes lead to the formation of supramolecular PNM ensembles containing crystalline building blocks. Such low-dimensional highly ordered regions create a new physical situation and provide unique physical properties based on electron-hole QC phenomena. In the case of asymmetrical crystalline structure, basic physical phenomena such as linear electro-optic, piezoelectric, and nonlinear optical effects, described by tensors of the odd rank, should be explored. Some of the PNM crystalline structures permit the existence of spontaneous electrical polarization and observation of ferroelectricity. The PNM crystalline arrangement creates highly porous nanotubes when various residues are packed into structural network with specific wettability and electrochemical properties. We report in this review on a wide research of PNM intrinsic physical properties, their electronic and optical properties related to QC effect, unique SHG, piezoelectricity and ferroelectric spontaneous polarization observed in PNT due to their asymmetric structure. We also describe PNM wettability phenomenon based on their nanoporous structure and its influence on electrochemical properties in PNM. The new bottom-up large scale technology of PNT physical vapor deposition and patterning combined with found physical effects at nanoscale, developed by us, opens the avenue for emerging nanotechnology applications of PNM in novel fields of nanophotonics, nanopiezotronics and energy storage devices. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.

Self-Assembled Three-Dimensional Graphene Macrostructures: Synthesis and Applications in Supercapacitors.

PubMed

Xu, Yuxi; Shi, Gaoquan; Duan, Xiangfeng

2015-06-16

Graphene and its derivatives are versatile building blocks for bottom-up assembly of advanced functional materials. In particular, with exceptionally large specific surface area, excellent electrical conductivity, and superior chemical/electrochemical stability, graphene represents the ideal material for various electrochemical energy storage devices including supercapacitors. However, due to the strong π-π interaction between graphene sheets, the graphene flakes tend to restack to form graphite-like powders when they are processed into practical electrode materials, which can greatly reduce the specific surface area and lead to inefficient utilization of the graphene layers for electrochemical energy storage. The self-assembly of two-dimensional graphene sheets into three-dimensional (3D) framework structures can largely retain the unique properties of individual graphene sheets and has recently garnered intense interest for fundamental investigations and potential applications in diverse technologies. In this Account, we review the recent advances in preparing 3D graphene macrostructures and exploring them as a unique platform for supercapacitor applications. We first describe the synthetic strategies, in which reduction of a graphene oxide dispersion above a certain critical concentration can induce the reduced graphene oxide sheets to cross-link with each other via partial π-π stacking interactions to form a 3D interconnected porous macrostructure. Multiple reduction strategies, including hydrothermal/solvothermal reduction, chemical reduction, and electrochemical reduction, have been developed for the preparation of 3D graphene macrostructures. The versatile synthetic strategies allow for easy incorporation of heteroatoms, carbon nanomaterials, functional polymers, and inorganic nanostructures into the macrostructures to yield diverse composites with tailored structures and properties. We then summarize the applications of the 3D graphene macrostructures for high-performance supercapacitors. With a unique framework structure in which the graphene sheets are interlocked in 3D space to prevent their restacking, the graphene macrostructures feature very high specific surface areas, rapid electron and ion transport, and superior mechanical strength. They can thus be directly used as supercapacitor electrodes with excellent specific capacitances, rate capabilities, and cycling stabilities. We finally discuss the current challenges and future opportunities in this research field. By regarding the graphene as both a single-atom-thick carbon sheet and a conjugated macromolecule, our work opens a new avenue to bottom-up self-assembly of graphene macromolecule sheets into functional 3D graphene macrostructures with remarkable electrochemical performances. We hope that this Account will promote further efforts toward fundamental investigation of graphene self-assembly and the development of advanced 3D graphene materials for their real-world applications in electrochemical energy storage devices and beyond.

Develop high activity, low cost non-PGM fuel cell electrocatalyst and stable supports

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

Colon-Mercado, H. R.; Elvington, M. C.; Garcia-Diaz, B. L.

2016-09-28

A unique approach has been developed to probe the non-PGM catalyst active site for the Oxygen Reduction Reaction (ORR) for PEMFC. Iron based functionalities have been engineered into Metallic Organic Framework (MOF) catalysts to evaluate their impact on activity for the ORR. A series of FePhen@MOF catalysts have been synthesized with varying [Fe] to investigate the effect on electrochemical and electrocatalytic properties. The magnitude of the Fe II/III redox couple and the electrochemical surface area are analyzed to determine if there is a correlation between [Fe] and the ORR onset potential and/or the relative number of active sites.

Enzyme-free monitoring of glucose utilization in stimulated macrophages using carbon nanotube-decorated electrochemical sensor

NASA Astrophysics Data System (ADS)

Madhurantakam, Sasya; Karnam, Jayanth Babu; Rayappan, John Bosco Balaguru; Krishnan, Uma Maheswari

2017-11-01

Carbon nanotubes (CNTs) have been extensively explored for a diverse range of applications due to their unique electrical and mechanical properties. CNT-incorporated electrochemical sensors have exhibited enhanced sensitivity towards the analyte molecule due to the excellent electron transfer properties of CNTs. In addition, CNTs possess a large surface area-to-volume ratio that favours the adhesion of analyte molecules as well as enhances the electroactive area. Most of the electrochemical sensors have employed CNTs as a nano-interface to promote electron transfer and as an immobilization matrix for enzymes. The present work explores the potential of CNTs to serve as a catalytic interface for the enzymeless quantification of glucose. The figure of merits for the enzymeless sensor was comparable to the performance of several enzyme-based sensors reported in literature. The developed sensor was successfully employed to determine the glucose utilization of unstimulated and stimulated macrophages. The significant difference in the glucose utilization levels in activated macrophages and quiescent cells observed in the present investigation opens up the possibilities of new avenues for effective medical diagnosis of inflammatory disorders.

Graphene as a signal amplifier for preparation of ultrasensitive electrochemical biosensors.

PubMed

Filip, Jaroslav; Kasák, Peter; Tkac, Jan

2015-01-01

Early diagnostics of diseases performed with minimal money and time consumption has become achievable due to recent advances in development of biosensors. These devices use biorecognition elements for selective interaction with an analyte and signal readout is obtained via different types of transducers. Operational characteristics of biosensors have been reported to improve substantially, when a diverse range of nanomaterials was employed. This review presents construction of electrochemical biosensors based on graphene, atomically thin 2D carbon crystals, which is currently intensively studied nanomaterial. The most attractive directions of graphene applications in biosensor preparation are discussed here including novel detection and amplification schemes exploiting graphene's unique electrochemical, physical and chemical properties. The future of graphene-based biosensors is most likely bright, but there is still a lot of work to do to fulfill high expectations.

Electrostatic Assembly of Nanomaterials for Hybrid Electrodes and Supercapacitors

NASA Astrophysics Data System (ADS)

Hammond, Paula

2015-03-01

Electrostatic assembly methods have been used to generate a range of new materials systems of interest for electrochemical energy and storage applications. Over the past several years, it has been demonstrated that carbon nanotubes, metals, metal oxides, polymeric nanomaterials, and biotemplated materials systems can be incorporated into ultrathin films to generate supercapacitors and battery electrodes that illustrate significant energy density and power. The unique ability to control the incorporation of such a broad range of materials at the nanometer length scale allows tailoring of the final properties of these unique composite systems, as well as the capability of creating complex micron-scale to nanoporous morphologies based on the scale of the nanomaterial that is absorbed within the structure, or the conditions of self-assembly. Recently we have expanded these capabilities to achieve new electrodes that are templated atop electrospun polmer fiber scaffolds, in which the polymer can be selectively removed to achieve highly porous materials. Spray-layer-by-layer and filtration methods of functionalized multiwall carbon nanotubes and polyaniline nanofibers enable the generation of electrode systems with unusually high surface. Incorporation of psuedocapacitive nanoparticles can enhance capacitive properties, and other catalytic or metallic nanoparticles can be implemented to enhance electrochemical or catalytic function.

Biomedical Probes Based on Inorganic Nanoparticles for Electrochemical and Optical Spectroscopy Applications

PubMed Central

Yakoh, Abdulhadee; Pinyorospathum, Chanika; Siangproh, Weena; Chailapakul, Orawon

2015-01-01

Inorganic nanoparticles usually provide novel and unique physical properties as their size approaches nanometer scale dimensions. The unique physical and optical properties of nanoparticles may lead to applications in a variety of areas, including biomedical detection. Therefore, current research is now increasingly focused on the use of the high surface-to-volume ratios of nanoparticles to fabricate superb chemical- or biosensors for various detection applications. This article highlights various kinds of inorganic nanoparticles, including metal nanoparticles, magnetic nanoparticles, nanocomposites, and semiconductor nanoparticles that can be perceived as useful materials for biomedical probes and points to the outstanding results arising from their use in such probes. The progress in the use of inorganic nanoparticle-based electrochemical, colorimetric and spectrophotometric detection in recent applications, especially bioanalysis, and the main functions of inorganic nanoparticles in detection are reviewed. The article begins with a conceptual discussion of nanoparticles according to types, followed by numerous applications to analytes including biomolecules, disease markers, and pharmaceutical substances. Most of the references cited herein, dating from 2010 to 2015, generally mention one or more of the following characteristics: a low detection limit, good signal amplification and simultaneous detection capabilities. PMID:26343676

Hierarchical structured Sm2O3 modified CuO nanoflowers as electrode materials for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Zhang, Xiaojuan; He, Mingqian; He, Ping; Liu, Hongtao; Bai, Hongmei; Chen, Jingchao; He, Shaoying; Zhang, Xingquan; Dong, Faqing; Chen, Yang

2017-12-01

By a simple and cost effective chemical precipitation-hydrothermal method, novel hierarchical structured Sm2O3 modified CuO nanoflowers are prepared and investigated as electrode materials for supercapacitors. The physical properties of prepared materials are characterized by XRD, FE-SEM, EDX and FTIR techniques. Furthermore, electrochemical performances of prepared materials are investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum in 1.0 M KOH electrolyte. The resulting Sm2O3 modified CuO based electrodes exhibit obviously enhanced capacitive properties owing to the unique nanostructures and strong synergistic effects. It is worth noting that the optimized SC-3 based electrode exhibits the best electrochemical performances in all prepared electrodes, including higher specific capacitance (383.4 F g-1 at 0.5 A g-1) and good rate capability (393.2 F g-1 and 246.3 F g-1 at 0.3 A g-1 and 3.0 A g-1, respectively), as well as excellent cycling stability (84.6% capacitance retention after 2000 cycles at 1.0 A g-1). The present results show that Sm2O3 is used as a promising modifier to change the morphology and improve electrochemical performances of CuO materials.

A comparitive investigation of electrochemical charge storage properties on β, γ, δ and λ-MnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Shafi, P. Muhammed; Johnson, Chelsea; Bose, A. Chandra

2018-04-01

Manganese dioxide and Manganese dioxide based materials have long been used in various energy storage systems because of their outstanding electrochemical behavior, low cost, and environmental compatibility. In recent years, many studies had focused on its nano scale applications due to the structural flexibility and the unique physicochemical properties. The basic crystal structure of manganese dioxide configures of one manganese atom surrounded by six oxygen atoms to form an octahedron. Here β-MnO2, γ-MnO2, λ-MnO2 and δ-MnO2 nanoparticles have been successfully synthesized by simple precipitation methods. Powder X-Ray Diffraction (XRD) analyses were performed for the identification and examination of the crystalline phase structures. Presence of functional groups and purity of the sample were evaluated by Fourier Transform Infrared Spectroscopy (FTIR). Morphology studies were carried out via Scanning Electron Microscopy (SEM). Electrochemical performances of the β, γ and δ phases were characterized by cyclic voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS). Among the four electrodes, δ-MnO2 exhibited the highest value for specific capacitance. These results show that the prepared MnO2 electrodes are good materials for supercapacitor application, especially δ-MnO2.

The Effect of Voltage Charging on the Transport Properties of Gold Nanotube Membranes.

PubMed

Experton, Juliette; Martin, Charles R

2018-05-01

Porous membranes are used in chemical separations and in many electrochemical processes and devices. Research on the transport properties of a unique class of porous membranes that contain monodisperse gold nanotubes traversing the entire membrane thickness is reviewed here. These gold nanotubes can act as conduits for ionic and molecular transports through the membrane. Because the tubes are electronically conductive, they can be electrochemically charged by applying a voltage to the membrane. How this "voltage charging" affects the transport properties of gold nanotube membranes is the subject of this Review. Experiments showing that voltage charging can be used to reversibly switch the membrane between ideally cation- and anion-transporting states are reviewed. Voltage charging can also be used to enhance the ionic conductivity of gold nanotube membranes. Finally, voltage charging to accomplish electroporation of living bacteria as they pass through gold nanotube membranes is reviewed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Critical V2O5/TeO2 Ratio Inducing Abrupt Property Changes in Vanadium Tellurite Glasses.

PubMed

Kjeldsen, Jonas; Rodrigues, Ana C M; Mossin, Susanne; Yue, Yuanzheng

2014-12-26

Transition metal containing glasses have unique electrical properties and are therefore often used for electrochemical applications, such as in batteries. Among oxide glasses, vanadium tellurite glasses exhibit the highest electronic conductivity and thus the high potential for applications. In this work, we investigate how the dynamic and physical properties vary with composition in the vanadium tellurite system. The results show that there exists a critical V(2)O(5) concentration of 45 mol %, above which the local structure is subjected to a drastic change with increasing V(2)O(5), leading to abrupt changes in both hardness and liquid fragility. Electronic conductivity does not follow the expected correlation to the valence state of the vanadium as predicted by the Mott-Austin equation but shows a linear correlation to the mean distance between vanadium ions. These findings could contribute to designing optimum vanadium tellurite compositions for electrochemical devices. The work gives insight into the mechanism of electron conduction in the vanadium tellurite systems.

Defining the origins of electron transfer at screen-printed graphene-like and graphite electrodes: MoO2 nanowire fabrication on edge plane sites reveals electrochemical insights.

PubMed

Rowley-Neale, Samuel J; Brownson, Dale A C; Banks, Craig E

2016-08-18

Molybdenum (di)oxide (MoO2) nanowires are fabricated onto graphene-like and graphite screen-printed electrodes (SPEs) for the first time, revealing crucial insights into the electrochemical properties of carbon/graphitic based materials. Distinctive patterns observed in the electrochemical process of nanowire decoration show that electron transfer occurs predominantly on edge plane sites when utilising SPEs fabricated/comprised of graphitic materials. Nanowire fabrication along the edge plane sites (and on edge plane like-sites/defects) of graphene/graphite is confirmed with Cyclic Voltammetry, Scanning Electron Microscopy (SEM) and Raman Spectroscopy. Comparison of the heterogeneous electron transfer (HET) rate constants (k°) at unmodified and nanowire coated SPEs show a reduction in the electrochemical reactivity of SPEs when the edge plane sites are effectively blocked/coated with MoO2. Throughout the process, the basal plane sites of the graphene/graphite electrodes remain relatively uncovered; except when the available edge plane sites have been utilised, in which case MoO2 deposition grows from the edge sites covering the entire surface of the electrode. This work clearly illustrates the distinct electron transfer properties of edge and basal plane sites on graphitic materials, indicating favourable electrochemical reactivity at the edge planes in contrast to limited reactivity at the basal plane sites. In addition to providing fundamental insights into the electron transfer properties of graphite and graphene-like SPEs, the reported simple, scalable, and cost effective formation of unique and intriguing MoO2 nanowires realised herein is of significant interest for use in both academic and commercial applications.

Understanding the Size-Dependent Sodium Storage Properties of Na2C6O6-Based Organic Electrodes for Sodium-Ion Batteries.

PubMed

Wang, Yaqun; Ding, Yu; Pan, Lijia; Shi, Ye; Yue, Zhuanghao; Shi, Yi; Yu, Guihua

2016-05-11

Organic electroactive materials represent a new generation of sustainable energy storage technology due to their unique features including environmental benignity, material sustainability, and highly tailorable properties. Here a carbonyl-based organic salt Na2C6O6, sodium rhodizonate (SR) dibasic, is systematically investigated for high-performance sodium-ion batteries. A combination of structural control, electrochemical analysis, and computational simulation show that rational morphological control can lead to significantly improved sodium storage performance. A facile antisolvent method was developed to synthesize microbulk, microrod, and nanorod structured SRs, which exhibit strong size-dependent sodium ion storage properties. The SR nanorod exhibited the best performance to deliver a reversible capacity of ∼190 mA h g(-1) at 0.1 C with over 90% retention after 100 cycles. At a high rate of 10 C, 50% of the capacity can be obtained due to enhanced reaction kinetics, and such high electrochemical activity maintains even at 80 °C. These results demonstrate a generic design route toward high-performance organic-based electrode materials for beyond Li-ion batteries. Using such a biomass-derived organic electrode material enables access to sustainable energy storage devices with low cost, high electrochemical performance and thermal stability.

Label-free immunosensor based on hyperbranched polyester for specific detection of α-fetoprotein.

PubMed

Niu, Yanlian; Yang, Tian; Ma, Shangshang; Peng, Fang; Yi, Meihui; Wan, Mimi; Mao, Chun; Shen, Jian

2017-06-15

A novel label-free immunosensor based on hyperbranched polyester nanoparticles with nitrite groups (HBPE-NO 2 ), which were synthesized through a simple one-step chemical reaction, was first developed for specific detection of α-fetoprotein (AFP), the tumor marker for liver cancer. The obtained HBPE-NO 2 nanoparticles (NPs) were characterized by the proton nuclear magnetic resonance spectroscopy ( 1 H NMR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). And the fabricated process of immunosensor was investigated by attenuated total reflection Fourier-transform infrared spectra (ATR-FTIR), static water contact angles, scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical performances of the AFP immunosensor were studied. Results indicated the prepared HBPE-NO 2 -modified immunosensor showed excellent electrochemical properties and satisfactory accuracy for the detection of AFP of the real clinical samples that attributed to the properties of the HBPE-NO 2 NPs, which had nanosized structure to increase the specific surface area and unique chemical reactivity for loading capacity of protein molecules. Construction of biosensors using the structure and properties of hyperbranched molecules will offer ideal electrode substrates, which provided more possibilities for the design of biosensor. Copyright © 2017 Elsevier B.V. All rights reserved.

Tailorable drug capacity of dexamethasone-loaded conducting polymer matrix

NASA Astrophysics Data System (ADS)

Krukiewicz, K.

2018-05-01

The unique properties of conducting polymers, which are in the same time biocompatible and electrically responsive materials, make them perfect candidates for controlled drug release systems. In this study, the electrically-triggered controlled release system based on dexamethasone-loaded poly (3, 4-ethylenedioxypyrrole) (PEDOP) matrix is described. It is shown that the electropolymerization conditions can facilitate or suppress the formation of PEDOP/Dex matrix, as well as they can have the effect on its electrochemical performance. The release experiments performed in three different modes show that the drug capacity of PEDOP matrix increases with the increase in Dex concentration in the step of matrix synthesis, and higher Dex concentrations make it easier to control the amount of Dex released in an electrically-triggered mode. These results confirm the importance of the careful optimization of immobilization conditions to maximize drug capacity of matrix and maintain its electrochemical properties.

Synthesis, spectroscopic and electrochemical characterization of secnidazole esters

NASA Astrophysics Data System (ADS)

Shahid, Hafiz Abdullah; Jahangir, Sajid; Hanif, Muddasir; Xiong, Tianrou; Muhammad, Haji; Wahid, Sana; Yousuf, Sammer; Qureshi, Naseem

2017-12-01

We report a low-cost, less toxic to environment and simple method for the esterification of secnidazole. This is first comprehensive structural characterization of novel secnidazole esters by the spectroscopic and electrochemical methods. The important EIMS fragmentation analysis showed unique contribution of heteroatom bonds explained by the fragmentation patterns. These peaks originate from the loss of single electron, loss of HCN, M-O, M-NO, M-NO2, M-C7H10N3O3, and M-C8H10N3O4. The comparison of 13C NMR predicted values with the experimental values showed that ChemBioDraw Ultra 14.0 has advantage of predicting aromatic (sp2) carbons, while MestReNova 6.1 predicts sp3 hybrid carbons more accurately. The electrochemical properties indicated an irreversible oxidation process and reversible reduction process in these ester molecules similar to the parent secnidazole.

Light-driven OR and XOR programmable chemical logic gates.

PubMed

Szaciłowski, Konrad; Macyk, Wojciech; Stochel, Grazyna

2006-04-12

Photoelectrodes made of nanocrystalline titanium dioxide modified with various pentacyanoferrates exhibit unique photoelectrochemical properties; photocurrent direction can be switched from anodic to cathodic and vice versa upon changes in photoelectrode potential and incident light wavelength (PhotoElectrochemical Photocurrent Switching, PEPS effect). At certain potentials, anodic photocurrent generated upon UV irradiation has the same intensity as the cathodic photocurrent generated upon visible irradiation. Under these conditions, simultaneous irradiation with UV and visible light results in compensation of anodic and cathodic photocurrents, and zero net photocurrent is observed. This process can be used for construction of unique light-driven chemical logic gates.

Design, hydrothermal synthesis and electrochemical properties of porous birnessite-type manganese dioxide nanosheets on graphene as a hybrid material for supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Ying; Yan, De; Zhuo, Renfu; Li, Shuankui; Wu, Zhiguo; Wang, Jun; Ren, Pingyuan; Yan, Pengxun; Geng, Zhongrong

2013-11-01

MnO2-graphene hybrid with a unique structure of porous birnessite-type manganese dioxide (MnO2) nanosheets on graphene has been designed and synthesized by a simple hydrothermal method. The formation mechanism of the hybrid is discussed based on a series of time-dependent experiments. Electrochemical measurements reveal that the MnO2-graphene electrode exhibits much higher specific capacitance (315 F g-1 at a current density of 0.2 A g-1) and better rate capability (even 193 F g-1 at 6 A g-1) compared with both the graphene and MnO2 electrodes. Moreover, the capacitance of MnO2-graphene electrode is still 87% retained after 2000 cycles at a charging rate of 3 A g-1. The superior capacitive performance of the hybrid is attributed to its unique structure, which provides good electronic conductivity, fast electron and ion transport, and high utilization of MnO2.

Meso-oblate spheroids of thermal-stabile linker-free aggregates with size-tunable subunits for reversible lithium storage.

PubMed

Deng, Da; Lee, Jim Yang

2014-01-22

The organization of nanoscale materials as building units into extended structures with specific geometry and functional properties is a challenging endeavor. Hereby, an environmentally benign, simple, and scalable method for preparation of stable, linker-free, self-supported, high-order 3D meso-oblate spheroids of CuO nanoparticle aggregates with size-tunable building nanounits for reversible lithium-ion storage is reported. In contrast to traditional spherical nanoparticle aggregation, a unique oblate spheroid morphology is achieved. The formation mechanism of the unusual oblate spheroid of aggregated nanoparticles is proposed. When tested for reversible lithium ion storage, the unique 3D meso-oblate spheroids of CuO nanoparticle aggregate demonstrated highly improved electrochemical performance (around ∼600 mAh/g over 20 cycles), which could be ascribed to the nanoporous aggregated mesostructure with abundant crystalline imperfection. Furthermore, the size of building units can be controlled (12 and 21 nm were tested) to further improve their electrochemical performance.

Exploitation of Unique Properties of Zeolites in the Development of Gas Sensors

PubMed Central

Zheng, Yangong; Li, Xiaogan; Dutta, Prabir K.

2012-01-01

The unique properties of microporous zeolites, including ion-exchange properties, adsorption, molecular sieving, catalysis, conductivity have been exploited in improving the performance of gas sensors. Zeolites have been employed as physical and chemical filters to improve the sensitivity and selectivity of gas sensors. In addition, direct interaction of gas molecules with the extraframework cations in the nanoconfined space of zeolites has been explored as a basis for developing new impedance-type gas/vapor sensors. In this review, we summarize how these properties of zeolites have been used to develop new sensing paradigms. There is a considerable breadth of transduction processes that have been used for zeolite incorporated sensors, including frequency measurements, optical and the entire gamut of electrochemical measurements. It is clear from the published literature that zeolites provide a route to enhance sensor performance, and it is expected that commercial manifestation of some of the approaches discussed here will take place. The future of zeolite-based sensors will continue to exploit its unique properties and use of other microporous frameworks, including metal organic frameworks. Zeolite composites with electronic materials, including metals will lead to new paradigms in sensing. Use of nano-sized zeolite crystals and zeolite membranes will enhance sensor properties and make possible new routes of miniaturized sensors. PMID:22666081

Gas-Phase Functionalization of Macroscopic Carbon Nanotube Fiber Assemblies: Reaction Control, Electrochemical Properties, and Use for Flexible Supercapacitors.

PubMed

Iglesias, Daniel; Senokos, Evgeny; Alemán, Belén; Cabana, Laura; Navío, Cristina; Marcilla, Rebeca; Prato, Maurizio; Vilatela, Juan J; Marchesan, Silvia

2018-02-14

The assembly of aligned carbon nanotubes (CNTs) into fibers (CNTFs) is a convenient approach to exploit and apply the unique physico-chemical properties of CNTs in many fields. CNT functionalization has been extensively used for its implementation into composites and devices. However, CNTF functionalization is still in its infancy because of the challenges associated with preservation of CNTF morphology. Here, we report a thorough study of the gas-phase functionalization of CNTF assemblies using ozone which was generated in situ from a UV source. In contrast with liquid-based oxidation methods, this gas-phase approach preserves CNTF morphology, while notably increasing its hydrophilicity. The functionalized material is thoroughly characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. Its newly acquired hydrophilicity enables CNTF electrochemical characterization in aqueous media, which was not possible for the pristine material. Through comparison of electrochemical measurements in aqueous electrolytes and ionic liquids, we decouple the effects of functionalization on pseudocapacitive reactions and quantum capacitance. The functionalized CNTF assembly is successfully used as an active material and a current collector in all-solid supercapacitor flexible devices with an ionic liquid-based polymer electrolyte.

Nanoparticle-Mediated Physical Exfoliation of Aqueous-Phase Graphene for Fabrication of Three-Dimensionally Structured Hybrid Electrodes.

PubMed

Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Noh, Seonmyeong; Ahn, Ki-Jin; Im, Kyungun; Kwon, Oh Seok; Yoon, Hyeonseok

2016-01-27

Monodispersed polypyrrole (PPy) nanospheres were physically incorporated as guest species into stacked graphene layers without significant property degradation, thereby facilitating the formation of unique three-dimensional hybrid nanoarchitecture. The electrochemical properties of the graphene/particulate PPy (GPPy) nanohybrids were dependent on the sizes and contents of the PPy nanospheres. The nanohybrids exhibited optimum electrochemical performance in terms of redox activity, charge-transfer resistance, and specific capacitance at an 8:1 PPy/graphite (graphene precursor) weight ratio. The packing density of the alternately stacked nanohybrid structure varied with the nanosphere content, indicating the potential for high volumetric capacitance. The nanohybrids also exhibited good long-term cycling stability because of a structural synergy effect. Finally, fabricated nanohybrid-based flexible all-solid state capacitor cells exhibited good electrochemical performance in an acidic electrolyte with a maximum energy density of 8.4 Wh kg(-1) or 1.9 Wh L(-1) at a maximum power density of 3.2 kW kg(-1) or 0.7 kW L(-1); these performances were based on the mass or packing density of the electrode materials.

Facile fabrication of self-assembled polyaniline nanotubes doped with D-tartaric acid for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Mu, Jingjing; Ma, Guofu; Peng, Hui; Li, Jiajia; Sun, Kanjun; Lei, Ziqiang

2013-11-01

Polyaniline (PANI) nanotubes with outstanding electrochemical properties have been successfully synthesized via a simple chemical template-free method in the presence of D-tartaric acid (D-TA) as the dopant, and ammonium persulfate ((NH4)2S2O8) as the oxidant. The morphologies and structures of PANI-(D-TA) with different [D-TA]/[aniline] molar ratios are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and X-ray diffraction (XRD). To assess the electrochemical properties of PANI-(D-TA) materials, cyclic voltammetry (CV) and galvanostatic charging-discharging measurements are performed. The PANI-(D-TA) nanotubes electrode, with [D-TA]/[aniline] molar ratio of 1:1, exhibits larger specific capacitance (as high as 625 F g-1 at 1 A g-1) and higher capacitance retention (77% of its initial capacitance after 500 cycles) in 1 M H2SO4 aqueous solution. The remarkable electrochemical characteristics of PANI-(D-TA) are mainly attributed to their unique nanotubular structures, which provide a high electrode/electrolyte contact area and short ions diffusion path. These novel PANI-(D-TA) nanotubes will be promising electrode materials for high-performance supercapacitors.

Nanoparticle-Mediated Physical Exfoliation of Aqueous-Phase Graphene for Fabrication of Three-Dimensionally Structured Hybrid Electrodes

PubMed Central

Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Noh, Seonmyeong; Ahn, Ki-Jin; Im, Kyungun; Kwon, Oh Seok; Yoon, Hyeonseok

2016-01-01

Monodispersed polypyrrole (PPy) nanospheres were physically incorporated as guest species into stacked graphene layers without significant property degradation, thereby facilitating the formation of unique three-dimensional hybrid nanoarchitecture. The electrochemical properties of the graphene/particulate PPy (GPPy) nanohybrids were dependent on the sizes and contents of the PPy nanospheres. The nanohybrids exhibited optimum electrochemical performance in terms of redox activity, charge-transfer resistance, and specific capacitance at an 8:1 PPy/graphite (graphene precursor) weight ratio. The packing density of the alternately stacked nanohybrid structure varied with the nanosphere content, indicating the potential for high volumetric capacitance. The nanohybrids also exhibited good long-term cycling stability because of a structural synergy effect. Finally, fabricated nanohybrid-based flexible all–solid state capacitor cells exhibited good electrochemical performance in an acidic electrolyte with a maximum energy density of 8.4 Wh kg−1 or 1.9 Wh L−1 at a maximum power density of 3.2 kW kg−1 or 0.7 kW L−1; these performances were based on the mass or packing density of the electrode materials. PMID:26813878

A versatile strategy toward binary three-dimensional architectures based on engineering graphene aerogels with porous carbon fabrics for supercapacitors.

PubMed

Song, Wei-Li; Song, Kuo; Fan, Li-Zhen

2015-02-25

Graphene-based supercapacitors and related flexible devices have attracted great attention because of the increasing demands in the energy storage. As promising three-dimensional (3D) nanostructures in the supercapacitor electrodes, graphene-based aerogels have been paid dramatic attention recently, and numerous methods have been developed for enhancing their performance in energy storage. In this study, an exclusive strategy is presented toward directly in situ growing reduced graphene oxide (RGO) aerogels inside the 3D porous carbon fabrics for engineering the interfaces of the resulting binary 3D architectures. Such unique architectures have shown various advantages in the improvements of the nanostructures and chemical compositions, allowing them to possess much enhanced electrochemical properties (391, 229, and 195 F g(-1) at current densities of 0.1, 1, and 5 A g(-1), respectively) with excellent cycling stability in comparison with the neat RGO aerogels. The results of the performance in the flexible all-solid-state supercapacitors along with discussion on the related mechanisms in the electrochemical properties indicate the remaining issues and associated opportunities in the development of advanced energy storage devices. This strategy is relatively facile, versatile, and tunable, which highlights a unique platform for engineering various 3D porous structures in many fields.

Layered Metal Nanoparticle Structures on Electrodes for Sensing, Switchable Controlled Uptake/Release, and Photo-electrochemical Applications.

PubMed

Tel-Vered, Ran; Kahn, Jason S; Willner, Itamar

2016-01-06

Layered metal nanoparticle (NP) assemblies provide highly porous and conductive composites of unique electrical and optical (plasmonic) properties. Two methods to construct layered metal NP matrices are described, and these include the layer-by-layer deposition of NPs, or the electropolymerization of monolayer-functionalized NPs, specifically thioaniline-modified metal NPs. The layered NP composites are used as sensing matrices through the use of electrochemistry or surface plasmon resonance (SPR) as transduction signals. The crosslinking of the metal NP composites with molecular receptors, or the imprinting of molecular recognition sites into the electropolymerized NP matrices lead to selective and chiroselective sensing interfaces. Furthermore, the electrosynthesis of redox-active, imprinted, bis-aniline bridged Au NP composites yields electrochemically triggered "sponges" for the switchable uptake and release of electron-acceptor substrates, and results in conductive surfaces of electrochemically controlled wettability. Also, photosensitizer-relay-crosslinked Au NP composites, or electrochemically polymerized layered semiconductor quantum dot/metal NP matrices on electrodes, are demonstrated as functional nanostructures for photoelectrochemical applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

2D nanomaterials based electrochemical biosensors for cancer diagnosis.

PubMed

Wang, Lu; Xiong, Qirong; Xiao, Fei; Duan, Hongwei

2017-03-15

Cancer is a leading cause of death in the world. Increasing evidence has demonstrated that early diagnosis holds the key towards effective treatment outcome. Cancer biomarkers are extensively used in oncology for cancer diagnosis and prognosis. Electrochemical sensors play key roles in current laboratory and clinical analysis of diverse chemical and biological targets. Recent development of functional nanomaterials offers new possibilities of improving the performance of electrochemical sensors. In particular, 2D nanomaterials have stimulated intense research due to their unique array of structural and chemical properties. The 2D materials of interest cover broadly across graphene, graphene derivatives (i.e., graphene oxide and reduced graphene oxide), and graphene-like nanomaterials (i.e., 2D layered transition metal dichalcogenides, graphite carbon nitride and boron nitride nanomaterials). In this review, we summarize recent advances in the synthesis of 2D nanomaterials and their applications in electrochemical biosensing of cancer biomarkers (nucleic acids, proteins and some small molecules), and present a personal perspective on the future direction of this area. Copyright © 2016 Elsevier B.V. All rights reserved.

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

Recent Advances in Electrochemical Biosensors Based on Fullerene-C60 Nano-Structured Platforms.

PubMed

Pilehvar, Sanaz; De Wael, Karolien

2015-11-23

Nanotechnology is becoming increasingly important in the field of (bio)sensors. The performance and sensitivity of biosensors is greatly improved with the integration of nanomaterials into their construction. Since its first discovery, fullerene-C60 has been the object of extensive research. Its unique and favorable characteristics of easy chemical modification, conductivity, and electrochemical properties has led to its tremendous use in (bio)sensor applications. This paper provides a concise review of advances in fullerene-C60 research and its use as a nanomaterial for the development of biosensors. We examine the research work reported in the literature on the synthesis, functionalization, approaches to nanostructuring electrodes with fullerene, and outline some of the exciting applications in the field of (bio)sensing.

Multi-Anion Intercalated Layered Double Hydroxide Nanosheet-Assembled Hollow Nanoprisms with Improved Pseudocapacitive and Electrocatalytic Properties.

PubMed

Li, Zhengping; Han, Fangchun; Li, Cheng; Jiao, Xiuling; Chen, Dairong

2018-05-04

Electrochemically active hollow nanostructured materials hold great promise in diverse energy conversion and storage applications, however, intricate synthesis steps and poor control over compositions and morphologies have limited the realization of delicate hollow structures with advanced functional properties. In this study, we demonstrate a one-step wet-chemical strategy for co-engineering the hollow nanostructure and anion intercalation of nickel cobalt layered double hydroxide (NiCo-LDH) to attain highly electrochemical active energy conversion and storage functionalities. Self-templated pseudomorphic transformation of cobalt acetate hydroxide solid nanoprisms using nickel nitrate leads to the construction of well-defined NiCo-LDH hollow nanoprisms (HNPs) with multi-anion intercalation. The unique hierarchical nanosheet-assembled hollow structure and efficiently expanded interlayer spacing offer an increased surface area and exposure of active sites, reduced mass and charge transfer resistance, and enhanced stability of the materials. This leads to a significant improvement in the pseudocapacitive and electrocatalytic properties of NiCo-LDH HNP with respect to specific capacitance, rate and cycling performance, and OER overpotential, outperforming most of the recently reported NiCo-based materials. This work establishes the potential of manipulating sacrificial template transformation for the design and fabrication of novel classes of functional materials with well-defined nanostructures for electrochemical applications and beyond. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solvothermal synthesis, electromagnetic and electrochemical properties of jellylike cylinder graphene-Mn3O4 composite with highly coupled effect

NASA Astrophysics Data System (ADS)

Long, Yuting; Xie, Junliang; Li, Hong; Liu, Zirui; Xie, Yahong

2017-12-01

Jellylike cylinder graphene-Mn3O4 composite with highly coupled effect was successfully synthesized by a simple solvothermal process. Without using toxic reducing agent and expensive equipment, this method is environmental compatible and suitable for low cost mass production. High capacitance Mn3O4 nanoparticles are homogeneously anchored on excellent conductivity graphene framework and a growth mechanism is hypothesized. Excellent electron conductivity and unique structure of Mn3O4-graphene composite give rise to various applications such as microwave absorber and electrode material. As a microwave absorber, the composite exhibits lowest reflection loss of -14.2 dB in the frequency range of 2-18 GHz. Good microwave absorption performance is due to the structure of the composite where conductive channels form between nano sized Mn3O4 and high conductivity graphene with defects and dangling bonds. As for electrochemical property, Mn3O4-graphene composite with coupled effect shows excellent performance with highest specific capacitance of 246.7 F g-1 in saturated K2SO4 at a scan rate of 5 mV s-1. Good electrochemical property is also attributed to the structure with high utilization of Mn3O4, fast charge carrier transmission, and excellent electronic conductivity. This composite shows a promising application in absorbing materials and electrodes.

Highly Flexible Self-Assembled V2O5 Cathodes Enabled by Conducting Diblock Copolymers

PubMed Central

An, Hyosung; Mike, Jared; Smith, Kendall A.; Swank, Lisa; Lin, Yen-Hao; L. Pesek, Stacy; Verduzco, Rafael; Lutkenhaus, Jodie L.

2015-01-01

Mechanically robust battery electrodes are desired for applications in wearable devices, flexible displays, and structural energy and power. In this regard, the challenge is to balance mechanical and electrochemical properties in materials that are inherently brittle. Here, we demonstrate a unique water-based self-assembly approach that incorporates a diblock copolymer bearing electron- and ion-conducting blocks, poly(3-hexylthiophene)-block-poly(ethyleneoxide) (P3HT-b-PEO), with V2O5 to form a flexible, tough, carbon-free hybrid battery cathode. V2O5 is a promising lithium intercalation material, but it remains limited by its poor conductivity and mechanical properties. Our approach leads to a unique electrode structure consisting of interlocking V2O5 layers glued together with micellar aggregates of P3HT-b-PEO, which results in robust mechanical properties, far exceeding the those obtained from conventional fluoropolymer binders. Only 5 wt % polymer is required to triple the flexibility of V2O5, and electrodes comprised of 10 wt % polymer have unusually high toughness (293 kJ/m3) and specific energy (530 Wh/kg), both higher than reduced graphene oxide paper electrodes. Furthermore, addition of P3HT-b-PEO enhances lithium-ion diffusion, eliminates cracking during cycling, and boosts cyclability relative to V2O5 alone. These results highlight the importance of tradeoffs between mechanical and electrochemical performance, where polymer content can be used to tune both aspects. PMID:26391053

Highly Flexible Self-Assembled V 2O 5 Cathodes Enabled by Conducting Diblock Copolymers

DOE PAGES

An, Hyosung; Mike, Jared; Smith, Kendall A.; ...

2015-09-22

Mechanically robust battery electrodes are desired for applications in wearable devices, flexible displays, and structural energy and power. In this regard, the challenge is to balance mechanical and electrochemical properties in materials that are inherently brittle. Here, we demonstrate a unique water-based self-assembly approach that incorporates a diblock copolymer bearing electron- and ion-conducting blocks, poly(3-hexylthiophene)-block-poly(ethyleneoxide) (P3HT-b-PEO), with V 2O 5 to form a flexible, tough, carbon-free hybrid battery cathode. V 2O 5 is a promising lithium intercalation material, but it remains limited by its poor conductivity and mechanical properties. Our approach leads to a unique electrode structure consisting of interlockingmore » V 2O 5 layers glued together with micellar aggregates of P3HT-b-PEO, which results in robust mechanical properties, far exceeding the those obtained from conventional fluoropolymer binders. Only 5 wt % polymer is required to triple the flexibility of V 2O 5, and electrodes comprised of 10 wt % polymer have unusually high toughness (293 kJ/m 3) and specific energy (530 Wh/kg), both higher than reduced graphene oxide paper electrodes. Furthermore, addition of P3HT-b-PEO enhances lithium-ion diffusion, eliminates cracking during cycling, and boosts cyclability relative to V 2O 5 alone. These results highlight the importance of tradeoffs between mechanical and electrochemical performance, where polymer content can be used to tune both aspects.« less

Fast solution combustion synthesis of porous NaFeTi3O8 with superior sodium storage properties

NASA Astrophysics Data System (ADS)

Zhao, Jin-Bao; Li, Xue; Xiao, Qian

2018-01-01

In this work, NaFeTi3O8 with three-dimensional porous net-like sheet morphology is firstly prepared by a simple and effective solution combustion method. Encouragingly, when being assessed as an anode electrode for sodium ion batteries, the NaFeTi3O8 net-like sheet composite exhibits superior electrochemical properties. We also study the effect of the combustion fuel glycine. The results indicate that the NaFeTi3O8 composite tends to be porous with glycine as the combustion fuel, which displays more excellent long cyclic stability (discharge capacity of 91 mA h g-1 after 1000 cycles at the current density of 0.5 A g-1) and superior rate performance (84.4 mA h g-1 even at 1.6 A g-1) than that of NaFeTi3O8 without glycine as the combustion agent. The enhanced electrochemical properties could be ascribed to the unique porous morphology, which achieves better electrolyte infiltration and faster ion diffusion. [Figure not available: see fulltext.

Two-Dimensional, Ordered, Double Transition Metals Carbides (MXenes)

DOE PAGES

Anasori, Babak; Xie, Yu; Beidaghi, Majid; ...

2015-07-24

The higher the chemical diversity and structural complexity of two-dimensional (2D) materials, the higher the likelihood they possess unique and useful properties. In this paper, density functional theory (DFT) is used to predict the existence of two new families of 2D ordered, carbides (MXenes), M' 2M"C 2 and M' 2M" 2C 3, where M' and M" are two different early transition metals. In these solids, M' layers sandwich M" carbide layers. By synthesizing Mo 2TiC 2T x, Mo 2Ti 2C 3T x, and Cr 2TiC 2T x (where T is a surface termination), we validated the DFT predictions. Since themore » Mo and Cr atoms are on the outside, they control the 2D flakes’ chemical and electrochemical properties. The latter was proven by showing quite different electrochemical behavior of Mo 2TiC 2T x and Ti 3C 2T x. Finally, this work further expands the family of 2D materials, offering additional choices of structures, chemistries, and ultimately useful properties.« less

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

Anasori, Babak; Xie, Yu; Beidaghi, Majid

The higher the chemical diversity and structural complexity of two-dimensional (2D) materials, the higher the likelihood they possess unique and useful properties. In this paper, density functional theory (DFT) is used to predict the existence of two new families of 2D ordered, carbides (MXenes), M' 2M"C 2 and M' 2M" 2C 3, where M' and M" are two different early transition metals. In these solids, M' layers sandwich M" carbide layers. By synthesizing Mo 2TiC 2T x, Mo 2Ti 2C 3T x, and Cr 2TiC 2T x (where T is a surface termination), we validated the DFT predictions. Since themore » Mo and Cr atoms are on the outside, they control the 2D flakes’ chemical and electrochemical properties. The latter was proven by showing quite different electrochemical behavior of Mo 2TiC 2T x and Ti 3C 2T x. Finally, this work further expands the family of 2D materials, offering additional choices of structures, chemistries, and ultimately useful properties.« less

In Situ Encapsulating α-MnS into N,S-Codoped Nanotube-Like Carbon as Advanced Anode Material: α → β Phase Transition Promoted Cycling Stability and Superior Li/Na-Storage Performance in Half/Full Cells.

PubMed

Liu, Dai-Huo; Li, Wen-Hao; Zheng, Yan-Ping; Cui, Zheng; Yan, Xin; Liu, Dao-Sheng; Wang, Jiawei; Zhang, Yu; Lü, Hong-Yan; Bai, Feng-Yang; Guo, Jin-Zhi; Wu, Xing-Long

2018-04-02

Incorporation of N,S-codoped nanotube-like carbon (N,S-NTC) can endow electrode materials with superior electrochemical properties owing to the unique nanoarchitecture and improved kinetics. Herein, α-MnS nanoparticles (NPs) are in situ encapsulated into N,S-NTC, preparing an advanced anode material (α-MnS@N,S-NTC) for lithium-ion/sodium-ion batteries (LIBs/SIBs). It is for the first time revealed that electrochemical α → β phase transition of MnS NPs during the 1st cycle effectively promotes Li-storage properties, which is deduced by the studies of ex situ X-ray diffraction/high-resolution transmission electron microscopy and electrode kinetics. As a result, the optimized α-MnS@N,S-NTC electrode delivers a high Li-storage capacity (1415 mA h g -1 at 50 mA g -1 ), excellent rate capability (430 mA h g -1 at 10 A g -1 ), and long-term cycling stability (no obvious capacity decay over 5000 cycles at 1 A g -1 ) with retained morphology. In addition, the N,S-NTC-based encapsulation plays the key roles on enhancing the electrochemical properties due to its high conductivity and unique 1D nanoarchitecture with excellent protective effects to active MnS NPs. Furthermore, α-MnS@N,S-NTC also delivers high Na-storage capacity (536 mA h g -1 at 50 mA g -1 ) without the occurrence of such α → β phase transition and excellent full-cell performances as coupling with commercial LiFePO 4 and LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathodes in LIBs as well as Na 3 V 2 (PO 4 ) 2 O 2 F cathode in SIBs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interpenetrating polyaniline-gold electrodes for SERS and electrochemical measurements

NASA Astrophysics Data System (ADS)

West, R. M.; Semancik, S.

2016-11-01

Facile fabrication of nanostructured electrode arrays is critical for development of bimodal SERS and electrochemical biosensors. In this paper, the variation of applied potential at a polyaniline-coated Pt electrode is used to selectivity deposit Au on the polyaniline amine sites or on the underlying Pt electrode. By alternating the applied potential, the Au is grown simultaneously from the top and the bottom of the polyaniline film, leading to an interpenetrated, nanostructured polymer-metal composite extending from the Pt electrode to the electrolyte solution. The resulting films have unique pH-dependent electrochemical properties, e.g. they retain electrochemical activity in both acidic and neutral solutions, and they also include SERS-active nanostructures. By varying the concentration of chloroaurate used during deposition, Au nanoparticles, nanodendrites, or nanosheets can be selectively grown. For the films deposited under optimal conditions, using 5 mmol/L chloroaurate, the SERS enhancement factor for Rhodamine 6G was found to be as high as 1.1 × 106 with spot-to-spot and electrode-to-electrode relative standard deviations as low as 8% and 12%, respectively. The advantages of the reported PANI-Au composite electrodes lie in their facile fabrication, enabling the targeted deposition of tunable nanostructures on sensing arrays, and their ability to produce orthogonal optical and electrochemical analytical results.

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.

Carbon nanomaterials-based electrochemical aptasensors.

PubMed

Wang, Zonghua; Yu, Jianbo; Gui, Rijun; Jin, Hui; Xia, Yanzhi

2016-05-15

Carbon nanomaterials (CNMs) have attracted increasing attention due to their unique electrical, optical, thermal, mechanical and chemical properties. CNMs are extensively applied in electronic, optoelectronic, photovoltaic and sensing devices fields, especially in bioassay technology. These excellent properties significantly depend on not only the functional atomic structures of CNMs, but also the interactions with other materials, such as gold nanoparticles, SiO2, chitosan, etc. This review systematically summarizes applications of CNMs in electrochemical aptasensors (ECASs). Firstly, definition and development of ECASs are introduced. Secondly, different ways of ECASs about working principles, classification and construction of CNMs are illustrated. Thirdly, the applications of different CNMs used in ECASs are discussed. In this review, different types of CNMs are involved such as carbon nanotubes, graphene, graphene oxide, etc. Besides, the newly emerging CNMs and CNMs-based composites are also discoursed. Finally, we demonstrate the future prospects of CNMs-based ECASs, and some suggestions about the near future development of CNMs-based ECASs are highlighted. Copyright © 2015 Elsevier B.V. All rights reserved.

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries.

PubMed

Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

2014-04-08

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries.

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

2014-04-01

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries.

Raman structural studies of the nickel electrode

NASA Technical Reports Server (NTRS)

Cornilsen, B. C.

1985-01-01

Raman spectroscopy is sensitive to empirically controlled nickel electrode structural variations, and has unique potential for structural characterization of these materials. How the structure relates to electrochemical properties is examined so that the latter can be more completely understood, controlled, and optimized. Electrodes were impregnated and cycled, and cyclic voltammetry is being used for electrochemical characterization. Structural variation was observed which has escaped detection using other methods. Structural changes are induced by: (1) cobalt doping, (2) the state of change or discharge, (3) the preparation conditions and type of buffer used, and (4) the formation process. Charged active mass has an NiOOH-type structure, agreeing with X-ray diffraction results. Discharged active mass, however, is not isostructural with beta-Ni(OH)2. Chemically prepared alpha phases are not isostructural either. A disordered structural model, containing point defects, is proposed for the cycled materials. This model explains K(+) incorporation. Band assignments were made and spectra interpreted for beta-Ni(OH)2, electrochemical NiOOH and chemically precipitated NiOOH.

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries

PubMed Central

Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

2014-01-01

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries. PMID:24710575

Synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel for electrochemical detection of dopamine.

PubMed

Li, Ruiyi; Yang, Tingting; Li, Zaijun; Gu, Zhiguo; Wang, Guangli; Liu, Junkang

2017-02-15

Integration of noble metal nanomaterials on graphene nanosheets potentially paves one way to improve their electronic, chemical and electrochemical properties. The study reported synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel composite (Pd@Au/N,S-MGA). The as-prepared composite offers a well-defined three-dimensional architecture with rich of mesopores. The Pd@Au nanoalloys were dispersed on the graphene framework networks and their active sites were fully exposed. The unique structure achieves to ultra high electron/ion conductivity, electrocatalytic activity and structural stability. The sensor based on the Pd@Au/N,S-MGA creates ultrasensitive electrochemical response towards dopamine due to significantly electrochemical synergy between Pd, Au and N,S-MGA. Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0 × 10 -9  M to 4.0 × 10 -5  M with the detection limit of 3.6 × 10 -10  M (S/N = 3). The analytical method provides the advantage of sensitivity, reproducibility, rapidity and long-term stability. It has been successfully applied in the detection of trace dopamine in biological samples. The study also opens a window on the electronic properties of graphene aerogel and metal nanomaterials as well their nanohybrids to meet needs of further applications as nanoelectronics in diagnosis, bioanalysis and catalysis. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

Recent advances in aptasensors based on graphene and graphene-like nanomaterials.

PubMed

Ping, Jianfeng; Zhou, Yubin; Wu, Yuanyuan; Papper, Vladislav; Boujday, Souhir; Marks, Robert S; Steele, Terry W J

2015-02-15

Graphene and graphene-like two-dimensional nanomaterials have aroused tremendous research interest in recent years due to their unique electronic, optical, and mechanical properties associated with their planar structure. Aptamers have exhibited many advantages as molecular recognition elements for sensing devices compared to traditional antibodies. The marriage of two-dimensional nanomaterials and aptamers has emerged many ingenious aptasensing strategies for applications in the fields of clinical diagnosis and food safety. This review highlights current advances in the development and application of two-dimensional nanomaterials-based aptasensors with the focus on two main signal-transducing mechanisms, i.e. electrochemical and optical. A special attention is paid to graphene, a one-atom thick layer of graphite with exceptional properties, representing a fastgrowing field of research. In view of the unique properties of two-dimensional nanostructures and their inherent advantages of synthetic aptamers, we expect that high-performance two-dimensional nanomaterials-based aptasensing devices will find extensive applications in environmental monitoring, biomedical diagnostics, and food safety. Copyright © 2014 Elsevier B.V. All rights reserved.

Role of Defects and Adsorbed Water Film in Influencing the Electrical, Optical and Catalytic Properties of Transition Metal Oxides

NASA Astrophysics Data System (ADS)

Wang, Qi

Transition metal oxides (TMOs) constitute a large group of materials that exhibit a wide range of optical, electrical, electrochemical, dielectric and catalytic properties, and thus making them highly regarded as promising materials for a variety of applications in next generation electronic, optoelectronic, catalytic, photonic, energy storage and energy conversion devices. Some of the unique properties of TMOs are their strong electron-electron correlations that exists between the valence electrons of narrow d- or f-shells and their ability to exist in variety of oxidation states. This gives TMOs an enormous range of fascinating electronic and other physical properties. Many of these remarkable properties of TMOs arises from the complex surface charge transfer processes at the oxide surface/electrochemical redox species interface and non-stoichiometry due to the presence of lattice vacancies that may cause significant perturbation to the electronic structure of the material. Stoichiometry, oxidation state of the metal center and lattice vacancy defects all play important roles in affecting the physical properties, electronic structures, device behavior and other functional properties of TMOs. However, the underlying relationships between them is not clearly known. For instance, the exchange of electrons between adsorbates and defects can lead to the passivation of existing defect states or formation of new defects, both of which affect defect equilibria, and consequently, functional properties. In depth understanding of the role of lattice defects on the electrical, catalytic and optical properties of TMOs is central to further expansion of the technological applications of TMO based devices. The focus of this work is to elucidate the interactions of vacancy defects with various electrochemical adsorbates in TMOs. The ability to directly probe the interactions of vacancy defects with gas and liquid phase species under in-operando conditions is highly desirable to obtain a mechanistic understanding of the charge transfer process. We have developed a spectroscopic technique for studying vacancy defects in TMOs using near-infrared photoluminescence (NIR-PL) spectroscopy and showed that this technique is uniquely suited for studying defect-adsorbate interactions. In this work, a series of studies were carried out to elucidate the underlying structure-defect-property correlations of TMOs and their role in catalyzing electrical and electrochemical properties. In the first study, we report a new type of electrical phase transition in p-type, non-stoichiometric nickel oxide involving a semiconductor-to-insulator-to-metal transition along with the complete change of conductivity from p- to n-type at room temperature induced by electrochemical Li+ intercalation. Direct observation of vacancy-ion interactions using in-situ NIR-PL show that the transition is a result of passivation of native nickel (cationic) vacancy defects and subsequent formation of oxygen (anionic) vacancy defects driven by Li+ insertion into the lattice. X-ray photoemission spectroscopy studies performed to examine the changes in the oxidation states of nickel due to defect interactions support the above conclusions. In the second study, main effects of oxygen vacancy defects on the electronic and optical properties of V2O5 nanowires were studied using in-situ Raman, photoluminescence, absorption, and photoemission spectroscopy. We show that both thermal reduction and electrochemical reduction via Li+ insertion results in the creation of oxygen vacancy defects in the crystal that leads to band filling and an increase in the optical band gap of V2O5 from 1.95 eV to 2.45 eV, an effect known as the Burstein-Moss effect. In the third study, we report a new type of semiconductor-adsorbed water interaction in metal oxides known as "electrochemical surface transfer doping," a phenomenon that has been previously been observed on hydrogen-terminated diamond, carbon nanotube, gallium nitride and zinc oxide. Most TMOs at room temperature are known to be strongly hydrated. We show that an adsorbed water film present on the surface of TMOs facilitates the dissolution of gaseous species and promotes charge transfers at the adsorbed-water/oxide interfaces. Further, we show the role of vacancy defects in enhancing catalytic processes by directly monitoring the charge transfer process between gaseous species and vacancy defects in non-stoichiometric p-type nickel oxide and n-type tungsten oxide using in-situ NIR-PL, electrical resistance, and X-ray photoelectron spectroscopy. We find the importance of adsorbed water and vacancy defects in affecting catalytic, electronic, electrical, and optical changes such as insulator-to-metal transitions and radiative emissions during electrochemical reactions. In addition, we demonstrate that electrochemical surface transfer doping exists in another system, specifically, in gallium nitride, and the presence of this adsorbed water film present on the surface of GaN induces electron transfer from GaN that leads to the formation of an electron depletion region on the surface.

Nanostructured Mo-based electrode materials for electrochemical energy storage.

PubMed

Hu, Xianluo; Zhang, Wei; Liu, Xiaoxiao; Mei, Yueni; Huang, Yunhui

2015-04-21

The development of advanced energy storage devices is at the forefront of research geared towards a sustainable future. Nanostructured materials are advantageous in offering huge surface to volume ratios, favorable transport features, and attractive physicochemical properties. They have been extensively explored in various fields of energy storage and conversion. This review is focused largely on the recent progress in nanostructured Mo-based electrode materials including molybdenum oxides (MoO(x), 2 ≤ x ≤ 3), dichalconides (MoX2, X = S, Se), and oxysalts for rechargeable lithium/sodium-ion batteries, Mg batteries, and supercapacitors. Mo-based compounds including MoO2, MoO3, MoO(3-y) (0 < y < 1), MMo(x)O(y) (M = Fe, Co, Ni, Ca, Mn, Zn, Mg, or Cd; x = 1, y = 4; x = 3, y = 8), MoS2, MoSe2, (MoO2)2P2O7, LiMoO2, Li2MoO3, etc. possess multiple valence states and exhibit rich chemistry. They are very attractive candidates for efficient electrochemical energy storage systems because of their unique physicochemical properties, such as conductivity, mechanical and thermal stability, and cyclability. In this review, we aim to provide a systematic summary of the synthesis, modification, and electrochemical performance of nanostructured Mo-based compounds, as well as their energy storage applications in lithium/sodium-ion batteries, Mg batteries, and pseudocapacitors. The relationship between nanoarchitectures and electrochemical performances as well as the related charge-storage mechanism is discussed. Moreover, remarks on the challenges and perspectives of Mo-containing compounds for further development in electrochemical energy storage applications are proposed. This review sheds light on the sustainable development of advanced rechargeable batteries and supercapacitors with nanostructured Mo-based electrode materials.

Recent Advances in Electrochemical Biosensors Based on Fullerene-C60 Nano-Structured Platforms

PubMed Central

Pilehvar, Sanaz; De Wael, Karolien

2015-01-01

Nanotechnology is becoming increasingly important in the field of (bio)sensors. The performance and sensitivity of biosensors is greatly improved with the integration of nanomaterials into their construction. Since its first discovery, fullerene-C60 has been the object of extensive research. Its unique and favorable characteristics of easy chemical modification, conductivity, and electrochemical properties has led to its tremendous use in (bio)sensor applications. This paper provides a concise review of advances in fullerene-C60 research and its use as a nanomaterial for the development of biosensors. We examine the research work reported in the literature on the synthesis, functionalization, approaches to nanostructuring electrodes with fullerene, and outline some of the exciting applications in the field of (bio)sensing. PMID:26610583

Electrochemical aptamer-based nanosensor fabricated on single Au nanowire electrodes for adenosine triphosphate assay.

PubMed

Wang, Dongmei; Xiao, Xiaoqing; Xu, Shen; Liu, Yong; Li, Yongxin

2018-01-15

In this work, single Au nanowire electrodes (AuNWEs) were fabricated by laser-assisted pulling/hydrofluoric acid (HF) etching process, which then were characterized by transmission electron microscopy (TEM), electrochemical method and finite-element simulation. The as-prepared single AuNWEs were used to construct electrochemical aptamer-based nanosensors (E-AB nanosensors) based on the formation of Au-S bond that duplex DNA tagged with methylene blue (MB) was modified on the surface of electrode. In the presence of adenosine triphosphate (ATP), the MB-labeled aptamer dissociated from the duplex DNA due to the strong specific affinity between aptamer and target, which lead to the reduction of MB electrochemical signals. Moreover, BSA was employed to further passivate electrode surface bonding sites for the stable of the sensor. The as-prepared E-AB nanosensor has been used for ATP assay with excellent sensitivity and selectivity, even in a complex system like cerebrospinal fluid of rat brain. Considering the unique properties of good stability, larger surface area and smaller overall dimensions, this E-AB nanosensor should be an ideal platform for widely sensing applications in living bio-system. Copyright © 2017 Elsevier B.V. All rights reserved.

Characteristics of biochar: Microchemical properties

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

Amonette, James E.; Joseph, Stephen

2009-03-13

Biochars, being derived from a variety of biological feedstocks that have been thermally degraded under a range of conditions, exhibit a correspondingly large range in composition and chemistry. Due in part to the somewhat chaotic nature of the thermal process itself, this chemical heterogeneity extends to the microscopic scale even within a single biochar. Thus, in the strictest sense, each biochar made under a particular feedstock/process combination presents a unique mixture of phases and microenvironments that gives rise to a unique set of chemical properties. In some respects, the chemical complexity of biochars rivals that of incipient soils. In thismore » chapter we focus on the chemical complexity of biochar as manifested primarily at a microscopic and molecular scale. We start by describing the biochar-formation process and how this influences the composition and nature of the solid phases, entrained oils, and their organization at the microscopic level. We then proceed to discuss the range of surface chemistries exhibited by biochars in terms of functional groups and electrochemical properties. We conclude with a discussion of the influence of these properties on the sorption of aqueous species at biochar surfaces.« less

A facile synthesis of 3D NiFe2O4 nanospheres anchored on a novel ionic liquid modified reduced graphene oxide for electrochemical sensing of ledipasvir: Application to human pharmacokinetic study.

PubMed

El-Wekil, Mohamed M; Mahmoud, Ashraf M; Alkahtani, Saad A; Marzouk, Adel A; Ali, Ramadan

2018-06-30

Novel and sensitive electrochemical sensor was fabricated for the assay of anti-HCV ledipasvir (LEDV) in different matrices. The designed sensor was based on 3D spinel ferromagnetic NiFe 2 O 4 nanospheres and reduced graphene oxide (RGO) supported by morpholinium acid sulphate (MHS), as an ionic liquid (RGO/NSNiFe 2 O 4 /MHS). This sensor design was assigned to synergistically tailor the unique properties of nanostructured ferrites, RGO, and ionic liquid to maximize the sensor response. Electrode modification prevented aggregation of NiFe 2 O 4, increasing electroactive surface area and allowed remarkable electro-catalytic oxidation of LEDV with an enhanced oxidation response. Differential pulse voltammetry was used for detection LEDV in complex matrices whereas; cyclic voltammetry and other techniques were employed to characterize the developed sensor properties. All experimental factors regarding sensor fabrication and chemical sensing properties were carefully studied and optimized. Under the optimum conditions, the designated sensor displayed a wide linear range (0.4-350 ng mL -1 ) with LOD of 0.133 ng mL -1 . Additionally, the proposed sensor demonstrated good selectivity, stability and reproducibility, enabling the quantitative detection of LEDV in Harvoni ® tablets, human plasma and in a pharmacokinetic study. Our findings suggest that the developed sensor is a potential prototype material for fabrication of high-performance electrochemical sensors. Copyright © 2018 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

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.

Polypyrrole based nanocomposites for supercapacitor applications: A review

NASA Astrophysics Data System (ADS)

Sardar, A.; Gupta, P. S.

2018-05-01

Recently conducting polymers have attracted great interest for supercapacitor applications. Among conducting polymers polypyrrole is most popular due to its unique electrical conductivity, optoelectrical properties, redox property and excellent environmental stability. In this article, we present a comprehensive review of polypyrrole and polypyrrole based nanocomposites for supercapacitor applications. We have included study of various parameters like power density, energy density, specific-capacitance by various authors for different kinds of nanocomposites where fillers are metal oxides, metal sulphides, graphene etc. Some polypyrrole nanocomposits show good electrochemical performances. The extremely stable supercapacitors with excellent flexibility and scalability hold considerable promise for the commerical application of flexible and wearable electronics.

Biological and chemical sensors based on graphene materials.

PubMed

Liu, Yuxin; Dong, Xiaochen; Chen, Peng

2012-03-21

Owing to their extraordinary electrical, chemical, optical, mechanical and structural properties, graphene and its derivatives have stimulated exploding interests in their sensor applications ever since the first isolation of free-standing graphene sheets in year 2004. This article critically and comprehensively reviews the emerging graphene-based electrochemical sensors, electronic sensors, optical sensors, and nanopore sensors for biological or chemical detection. We emphasize on the underlying detection (or signal transduction) mechanisms, the unique roles and advantages of the used graphene materials. Properties and preparations of different graphene materials, their functionalizations are also comparatively discussed in view of sensor development. Finally, the perspective and current challenges of graphene sensors are outlined (312 references).

Ruthenium and osmium complexes that bear functional azolate chelates for dye-sensitized solar cells.

PubMed

Chi, Yun; Wu, Kuan-Lin; Wei, Tzu-Chien

2015-05-01

The preparation of sensitizers for dye-sensitized solar cells (DSSCs) represents an active area of research for both sustainability and renewable energy. Both Ru(II) and Os(II) metal sensitizers offer unique photophysical and electrochemical properties that arise from the intrinsic electronic properties, that is, the higher propensity to form the lower-energy metal-to-ligand charge-transfer (MLCT) transition, and their capability to support chelates with multiple carboxy groups, which serve as a bridge to the metal oxide and enable efficient injection of the photoelectron. Here we present an overview of the synthesis and testing of these metal sensitizers that bear functional azolate chelates (both pyrazolate and triazolate), which are capable of modifying the metal sensitizers in a systematic and beneficial manner. Basic principles of the molecular designs, the structural relationship to the photophysical and electrochemical properties, and performances of the as-fabricated DSSCs are highlighted. The success in the breakthrough of the synthetic protocols and potential applications might provide strong stimulus for the future development of technologies such as DSSCs, organic light-emitting diodes, solar water splitting, and so forth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two‐Dimensional Fluorinated Graphene: Synthesis, Structures, Properties and Applications

PubMed Central

Long, Peng; Feng, Yiyu; Li, Yu

2016-01-01

Fluorinated graphene, an up‐rising member of the graphene family, combines a two‐dimensional layer‐structure, a wide bandgap, and high stability and attracts significant attention because of its unique nanostructure and carbon–fluorine bonds. Here, we give an extensive review of recent progress on synthetic methods and C–F bonding; additionally, we present the optical, electrical and electronic properties of fluorinated graphene and its electrochemical/biological applications. Fluorinated graphene exhibits various types of C–F bonds (covalent, semi‐ionic, and ionic bonds), tunable F/C ratios, and different configurations controlled by synthetic methods including direct fluorination and exfoliation methods. The relationship between the types/amounts of C–F bonds and specific properties, such as opened bandgap, high thermal and chemical stability, dispersibility, semiconducting/insulating nature, magnetic, self‐lubricating and mechanical properties and thermal conductivity, is discussed comprehensively. By optimizing the C–F bonding character and F/C ratios, fluorinated graphene can be utilized for energy conversion and storage devices, bioapplications, electrochemical sensors and amphiphobicity. Based on current progress, we propose potential problems of fluorinated graphene as well as the future challenge on the synthetic methods and C‐F bonding character. This review will provide guidance for controlling C–F bonds, developing fluorine‐related effects and promoting the application of fluorinated graphene. PMID:27981018

Unique Urchin-like Ca2Ge7O16 Hierarchical Hollow Microspheres as Anode Material for the Lithium Ion Battery.

PubMed

Li, Dan; Feng, Chuanqi; Liu, Hua Kun; Guo, Zaiping

2015-06-10

Germanium is an outstanding anode material in terms of electrochemical performance, especially rate capability, but its developments are hindered by its high price because it is rare in the crust of earth, and its huge volume variation during the lithium insertion and extraction. Introducing other cheaper elements into the germanium-based material is an efficient way to dilute the high price, but normally sacrifice its electrochemical performance. By the combination of nanostructure design and cheap element (calcium) introduction, urchin-like Ca2Ge7O16 hierarchical hollow microspheres have been successfully developed in order to reduce the price and maintain the good electrochemical properties of germanium-based material. The electrochemical test results in different electrolytes show that ethylene carbonate/dimethyl carbonate/diethyl carbonate (3/4/3 by volume) with 5 wt% fluoroethylene carbonate additive is the most suitable solvent for the electrolyte. From the electrochemical evaluation, the as-synthesized Ca2Ge7O16 hollow microspheres exhibit high reversible specific capacity of up to 804.6 mA h g(-1) at a current density of 100 mA g(-1) after 100 cycles and remarkable rate capability of 341.3 mA h g(-1) at a current density of 4 A g(-1). The growth mechanism is proposed based on our experimental results on the growth process.

Atomic force microscopy for two-dimensional materials: A tutorial review

NASA Astrophysics Data System (ADS)

Zhang, Hang; Huang, Junxiang; Wang, Yongwei; Liu, Rui; Huai, Xiulan; Jiang, Jingjing; Anfuso, Chantelle

2018-01-01

Low dimensional materials exhibit distinct properties compared to their bulk counterparts. A plethora of examples have been demonstrated in two-dimensional (2-D) materials, including graphene and transition metal dichalcogenides (TMDCs). These novel and intriguing properties at the nano-, molecular- and even monatomic scales have triggered tremendous interest and research, from fundamental studies to practical applications and even device fabrication. The unique behaviors of 2-D materials result from the special structure-property relationships that exist between surface topographical variations and mechanical responses, electronic structures, optical characteristics, and electrochemical properties. These relationships are generally convoluted and sensitive to ambient and external perturbations. Characterizing these systems thus requires techniques capable of providing multidimensional information under controlled environments, such as atomic force microscopy (AFM). Today, AFM plays a key role in exploring the basic principles underlying the functionality of 2-D materials. In this tutorial review, we provide a brief introduction to some of the unique properties of 2-D materials, followed by a summary of the basic principles of AFM and the various AFM modes most appropriate for studying these systems. Following that, we will focus on five important properties of 2-D materials and their characterization in more detail, including recent literature examples. These properties include nanomechanics, nanoelectromechanics, nanoelectrics, nanospectroscopy, and nanoelectrochemistry.

Synthesis and Electrochemical Property of LiMn2O4 Porous Hollow Nanofiber as Cathode for Lithium-Ion Batteries.

PubMed

Duan, Lianfeng; Zhang, Xueyu; Yue, Kaiqiang; Wu, Yue; Zhuang, Jian; Lü, Wei

2017-12-01

The LiMn 2 O 4 hollow nanofibers with a porous structure have been synthesized by modified electrospinning techniques and subsequent thermal treatment. The precursors were electrospun directly onto the fluorine-doped tin oxide (FTO) glass. The heating rate and FTO as substrate play key roles on preparing porous hollow nanofiber. As cathode materials for lithium-ion batteries (LIBs), LiMn 2 O 4 hollow nanofibers showed the high specific capacity of 125.9 mAh/g at 0.1 C and a stable cycling performance, 105.2 mAh/g after 400 cycles. This unique structure could relieve the structure expansion effectively and provide more reaction sites as well as shorten the diffusion path for Li + for improving electrochemical performance for LIBs.

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.

High-Performance Supercapacitor Electrode Based on Cobalt Oxide-Manganese Dioxide-Nickel Oxide Ternary 1D Hybrid Nanotubes.

PubMed

Singh, Ashutosh K; Sarkar, Debasish; Karmakar, Keshab; Mandal, Kalyan; Khan, Gobinda Gopal

2016-08-17

We report a facile method to design Co3O4-MnO2-NiO ternary hybrid 1D nanotube arrays for their application as active material for high-performance supercapacitor electrodes. This as-prepared novel supercapacitor electrode can store charge as high as ∼2020 C/g (equivalent specific capacitance ∼2525 F/g) for a potential window of 0.8 V and has long cycle stability (nearly 80% specific capacitance retains after successive 5700 charge/discharge cycles), significantly high Coulombic efficiency, and fast response time (∼0.17s). The remarkable electrochemical performance of this unique electrode material is the outcome of its enormous reaction platform provided by its special nanostructure morphology and conglomeration of the electrochemical properties of three highly redox active materials in a single unit.

Flexible superior electrode architectures based on three-dimensional porous spinous α-Fe2O3 with a high performance as a supercapacitor.

PubMed

Nan, Honghong; Yu, Liutao; Ma, Wenqin; Geng, Baoyou; Zhang, Xiaojun

2015-05-28

Flexible supercapacitors have recently attracted increasing attention as they show unique promising advantages, such as flexibility and shape diversity, and they are light-weight and so on. Herein, we designed a series of 3D porous spinous iron oxide materials synthesized on a thin iron plate through a facile method under mild conditions. The unique nanostructural features endow them with excellent electrochemical performance. The electrochemical properties of the integrated electrodes as active electrode materials for supercapacitors have been investigated using different electrochemical techniques including cyclic voltammetry, and galvanostatic charge-discharge in Na2SO4 and LiPF6/EC : DEC electrolyte solutions. These integrated electrodes showed high specific capacitance (as high as 524.6 F g(-1) at the current density of 1 A g(-1)) in 1.0 M Na2SO4 (see Table S1). Moreover, the integrated electrodes also show high power densities and high energy densities in a LiPF6/EC : DEC electrolyte solution; for example, the energy densities were 319.3, 252.5, 152.1, 74.13 and 38.6 W h kg(-1) at different power densities of 8.81, 21.59, 56.65, 92.09 and 152.64 kW kg(-1), respectively. Additionally, the flexible superior electrode exhibited excellent stability with capacitance retention of 92.9% after 5000 cycles. Therefore, such flexible integrated devices might be used in smart and portable electronics.

In situ electrochemical-electron spin resonance investigations of multi-electron redox reaction for organic radical cathodes

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

Huang, Qian; Walter, Eric D.; Cosimbescu, Lelia

2016-02-29

Organic radical batteries (ORBs) bearing robust radical polymers as energy storage species, are emerging promisingly with durable high energy and power characteristics by unique tunable redox properties. Here we report the development and application of in situ electrochemical-electron spin resonance (ESR) methodologies to identify the charge transfer mechanism of Poly(2,2,6,6- tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) based organic radical composite cathodes in the charge-discharge process of lithium half cells. The in situ experiments allow each electrochemical state to be associated with the chemical state (or environment) of the radical species upon the cell cycling. In situ ESR spectra of the composite cathode demonstratemore » a two-electron redox reaction of PTMA. Moreover, two different local environments of radical species are found in the composite electrode that includes both concentrated and isolated radicals. These two types of radicals show similarities during the redox reaction process while behave quite differently in the non-faradic reaction of ion sorption/desorption on the electrode surface.« less

Nitrogen-doped hollow carbon spheres wrapped with graphene nanostructure for highly sensitive electrochemical sensing of parachlorophenol.

PubMed

Yi, Yinhui; Zhu, Gangbing; Sun, Heng; Sun, Jianfan; Wu, Xiangyang

2016-12-15

Owing to awfully harmful to the environment and human health, the qualitative and quantitative determination of parachlorophenol (PCP) is of great significance. In this paper, by using silica@polydopamine as template, nitrogen-doped hollow carbon spheres wrapped with reduced graphene oxide (NHCNS@RG) nanostructure was prepared successfully via a self-assembly approach due to the electrostatic interaction, and the obtained NHCNS@RG could exhibit the unique properties of NHCNS and RG: the NHCNS could impede the aggregation tendency of RG and possess high electrocatalytic activity; the RG enlarges the contacting area and offers many area-normalized edge-plane structures and active sites. Scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction and electrochemical method were used to characterize the morphology and structure of NHCNS@RG. Then, the NHCNS@RG hybrids were applied for the electrochemical sensing of PCP, under the optimized conditions, the detection limit of PCP obtained in this work is 0.01μM and the linear range is 0.03-38.00μM. Copyright © 2016 Elsevier B.V. All rights reserved.

Clay-Inspired MXene-Based Electrochemical Devices and Photo-Electrocatalyst: State-of-the-Art Progresses and Challenges.

PubMed

Wang, Hou; Wu, Yan; Yuan, Xingzhong; Zeng, Guangming; Zhou, Jin; Wang, Xin; Chew, Jia Wei

2018-03-01

MXene, an important and increasingly popular category of postgraphene 2D nanomaterials, has been rigorously investigated since early 2011 because of advantages including flexible tunability in element composition, hydrophobicity, metallic nature, unique in-plane anisotropic structure, high charge-carrier mobility, tunable band gap, and favorable optical and mechanical properties. To fully exploit these potentials and further expand beyond the existing boundaries, novel functional nanostructures spanning monolayer, multilayer, nanoparticles, and composites have been developed by means of intercalation, delamination, functionalization, hybridization, among others. Undeniably, the cutting-edge developments and applications of clay-inspired 2D MXene platform as electrochemical electrode or photo-electrocatalyst have conferred superior performance and have made significant impact in the field of energy and advanced catalysis. This review provides an overview of the fundamental properties and synthesis routes of pure MXene, functionalized MXene and their hybrids, highlights the state-of-the-art progresses of MXene-based applications with respect to supercapacitors, batteries, electrocatalysis and photocatalysis, and presents the challenges and prospects in the burgeoning field. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

2D Black Phosphorus: from Preparation to Applications for Electrochemical Energy Storage

PubMed Central

Wu, Shuxing

2018-01-01

Abstract Black phosphorus (BP) is rediscovered as a 2D layered material. Since its first isolation in 2014, 2D BP has triggered tremendous interest in the fields of condensed matter physics, chemistry, and materials science. Given its unique puckered monolayer geometry, 2D BP displays many unprecedented properties and is being explored for use in numerous applications. The flexibility, large surface area, and good electric conductivity of 2D BP make it a promising electrode material for electrochemical energy storage devices (EESDs). Here, the experimental and theoretical progress of 2D BP is presented on the basis of its preparation methods. The structural and physiochemical properties, air instability, passivation, and EESD applications of 2D BP are discussed systemically. Specifically, the latest research findings on utilizing 2D BP in EESDs, such as lithium‐ion batteries, supercapacitors, and emerging technologies (lithium–sulfur batteries, magnesium‐ion batteries, and sodium‐ion batteries), are summarized. On the basis of the current progress, a few personal perspectives on the existing challenges and future research directions in this developing field are provided. PMID:29876201

Nanoscale surface modification of Li-rich layered oxides for high-capacity cathodes in Li-ion batteries

NASA Astrophysics Data System (ADS)

Lan, Xiwei; Xin, Yue; Wang, Libin; Hu, Xianluo

2018-03-01

Li-rich layered oxides (LLOs) have been developed as a high-capacity cathode material for Li-ion batteries, but the structural complexity and unique initial charging behavior lead to several problems including large initial capacity loss, capacity and voltage fading, poor cyclability, and inferior rate capability. Since the surface conditions are critical to electrochemical performance and the drawbacks, nanoscale surface modification for improving LLO's properties is a general strategy. This review mainly summarizes the surface modification of LLOs and classifies them into three types of surface pre-treatment, surface gradient doping, and surface coating. Surface pre-treatment usually introduces removal of Li2O for lower irreversible capacity while surface doping is aimed to stabilize the structure during electrochemical cycling. Surface coating layers with different properties, protective layers to suppress the interface side reaction, coating layers related to structural transformation, and electronic/ionic conductive layers for better rate capability, can avoid the shortcomings of LLOs. In addition to surface modification for performance enhancement, other strategies can also be investigated to achieve high-performance LLO-based cathode materials.

Hierarchical nanostructured conducting polymer hydrogel with high electrochemical activity

PubMed Central

Pan, Lijia; Yu, Guihua; Zhai, Dongyuan; Lee, Hye Ryoung; Zhao, Wenting; Liu, Nian; Wang, Huiliang; Tee, Benjamin C.-K.; Shi, Yi; Cui, Yi; Bao, Zhenan

2012-01-01

Conducting polymer hydrogels represent a unique class of materials that synergizes the advantageous features of hydrogels and organic conductors and have been used in many applications such as bioelectronics and energy storage devices. They are often synthesized by polymerizing conductive polymer monomer within a nonconducting hydrogel matrix, resulting in deterioration of their electrical properties. Here, we report a scalable and versatile synthesis of multifunctional polyaniline (PAni) hydrogel with excellent electronic conductivity and electrochemical properties. With high surface area and three-dimensional porous nanostructures, the PAni hydrogels demonstrated potential as high-performance supercapacitor electrodes with high specific capacitance (∼480 F·g-1), unprecedented rate capability, and cycling stability (∼83% capacitance retention after 10,000 cycles). The PAni hydrogels can also function as the active component of glucose oxidase sensors with fast response time (∼0.3 s) and superior sensitivity (∼16.7 μA·mM-1). The scalable synthesis and excellent electrode performance of the PAni hydrogel make it an attractive candidate for bioelectronics and future-generation energy storage electrodes. PMID:22645374

Facile synthesis and electrochemical properties of continuous porous spheres assembled from defect-rich, interlayer-expanded, and few-layered MoS2/C nanosheets for reversible lithium storage

NASA Astrophysics Data System (ADS)

Chen, Biao; Lu, Huihui; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; He, Chunnian; Ma, Liying

2018-05-01

Hollow or continuous porous hierarchical MoS2/C structures with large Li-ion and electron transport kinetics, and high structural stability are urgent needs for their application in lithium ion batteries. In this regard, a novel continuous porous micro-sphere constructed from defect-rich, interlayer-expanded, and few-layered MoS2/C nanosheets is successfully synthesized through a facile one-pot hydrothermal method. The polyvinyl pyrrolidone surfactant serves as carbon source and supporter, while the CS2 works as soft template and sulfur source during hydrothermal process. The morphologies, structures, and electrochemical properties are systematically characterized. Importantly, it should be noted that the unique porous micro-spheres with merits of rich-defect, expanded-interlayer, few-layer (<5 layers), abundant pores and integrating carbon are favorable for lithium ion batteries application. When the uniform composites are used as lithium ion batteries anode materials, they deliver a high reversible capacity, excellent cycling performance (average capacity fading of 0.037% per cycle at 0.2 A g-1), and good rate capability.

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.

Uniquely confining Cu2S nanoparticles in graphitized carbon fibers for enhanced oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Zhao, Xiaoqian; Liu, Li; Zhang, Yan; Zhang, Huijuan; Wang, Yu

2017-08-01

Up to now, the literature on Cu2S with specific morphology applied to oxygen evolution reaction (OER) in the electrocatalytic field has been limited. In this work, unique peapod-like Cu2S/C exhibiting superb electrocatalytic performance toward OER is successfully synthesized, by employing Cu(OH)2 nanorods as the template and nontoxic glucose as the carbon source and then annealing with sublimed sulfur. It can be seen that this work explores a new application area for Cu2S. More precisely, the novel morphology contributes to increasing the electrochemical active surface area effectively and promoting contact between the Cu2S nanoparticles and the electrolyte. During electrochemical measurements, the peapod-like Cu2S/C shows enhanced electrocatalytic activity with a low overpotential of 401 mV at the current density of 10 mA cm-2 and a Tafel slope of 52 mV dec-1. More importantly, our material is able to maintain stability for at least 8 h at constant potential and the current loss is negligible after 2000 cycles. Obviously, these striking properties fully demonstrate that the peapod-like Cu2S/C as an efficient catalyst shows great promise for OER.

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions.

PubMed

Samu, Gergely F; Scheidt, Rebecca A; Kamat, Prashant V; Janáky, Csaba

2018-02-13

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and for assembling them into hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr 3 and hybrid organic-inorganic MAPbI 3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. The presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that comparisons can more easily be made.

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.

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

Nitrogen-Doped Carbon Nanotube/Graphite Felts as Advanced Electrode Materials for Vanadium Redox Flow Batteries.

PubMed

Wang, Shuangyin; Zhao, Xinsheng; Cochell, Thomas; Manthiram, Arumugam

2012-08-16

Nitrogen-doped carbon nanotubes have been grown, for the first time, on graphite felt (N-CNT/GF) by a chemical vapor deposition approach and examined as an advanced electrode for vanadium redox flow batteries (VRFBs). The unique porous structure and nitrogen doping of N-CNT/GF with increased surface area enhances the battery performance significantly. The enriched porous structure of N-CNTs on graphite felt could potentially facilitate the diffusion of electrolyte, while the N-doping could significantly contribute to the enhanced electrode performance. Specifically, the N-doping (i) modifies the electronic properties of CNT and thereby alters the chemisorption characteristics of the vanadium ions, (ii) generates defect sites that are electrochemically more active, (iii) increases the oxygen species on CNT surface, which is a key factor influencing the VRFB performance, and (iv) makes the N-CNT electrochemically more accessible than the CNT.

3D flower-like hierarchical Ag@nickel-cobalt hydroxide microsphere with enhanced electrochemical properties

NASA Astrophysics Data System (ADS)

Lv, Zijian; Zhong, Qin; Bu, Yunfei; Wu, Junpeng

2016-10-01

The morphology and electrical conductivity are essential to electrochemical performance of electrode materials in renewable energy conversion and storage technologies such as fuel cells and supercapacitors. Here, we explored a facile method to grow Ag@nickel-cobalt layered double hydroxide (Ag@Ni/Co-LDHs) with 3D flower-like microsphere structure. The results show the morphology of Ni/Co-LDHs varies with the introduction of Ag species. The prepared Ag@Ni/Co-LDHs not only exhibits an open hierarchical structure with high specific capacitance but also shows good electrical conductivity to support fast electron transport. Benefiting from the unique structural features, these flower-like Ag@Ni/Co-LDHs microspheres have impressive specific capacitance as high as 1768 F g-1 at 1 A g-1. It can be concluded that engineering the structure of the electrode can increase the efficiency of the specific capacitance as a battery-type electrode for hybrid supercapacitors.

Ultrasensitive electrochemical cocaine biosensor based on reversible DNA nanostructure.

PubMed

Sheng, Qinglin; Liu, Ruixiao; Zhang, Sai; Zheng, Jianbin

2014-01-15

We proposed an ultrasensitive electrochemical cocaine biosensor based on the three-dimensional (3D) DNA structure conversion of nanostructure from Triangular Pyramid Frustum (TPFDNA) to Equilateral Triangle (ETDNA). The presence of cocaine triggered the aptamer-composed DNA nanostructure change from "Close" to "Open", leading to obvious faradaic impedance changes. The unique properties with excellent stability and specific rigid structure of the 3D DNA nanostructure made the biosensing functions stable, sensitive, and regenerable. The Faradaic impedance responses were linearly related to cocaine concentration between 1.0 nM and 2.0 μM with a correlation coefficient of 0.993. The limit of detection was calculated to be 0.21 nM following IUPAC recommendations (3Sb/b). It is expected that the distinctive features of DNA nanostructure would make it potentially advantageous for a broad range of biosensing, bionanoelectronics, and therapeutic applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Photo Protection of Haematococcus pluvialis Algae by Astaxanthin: Unique Properties of Astaxanthin Deduced by EPR, Optical and Electrochemical Studies

PubMed Central

Focsan, A. Ligia; Polyakov, Nikolay E.; Kispert, Lowell D.

2017-01-01

The antioxidant astaxanthin is known to accumulate in Haematococcus pluvialis algae under unfavorable environmental conditions for normal cell growth. The accumulated astaxanthin functions as a protective agent against oxidative stress damage, and tolerance to excessive reactive oxygen species (ROS) is greater in astaxanthin-rich cells. The detailed mechanisms of protection have remained elusive, however, our Electron Paramagnetic Resonance (EPR), optical and electrochemical studies on carotenoids suggest that astaxanthin’s efficiency as a protective agent could be related to its ability to form chelate complexes with metals and to be esterified, its inability to aggregate in the ester form, its high oxidation potential and the ability to form proton loss neutral radicals under high illumination in the presence of metal ions. The neutral radical species formed by deprotonation of the radical cations can be very effective quenchers of the excited states of chlorophyll under high irradiation. PMID:29065482

3D nitrogen-doped graphene aerogel nanomesh: Facile synthesis and electrochemical properties as the electrode materials for supercapacitors

NASA Astrophysics Data System (ADS)

Su, Xiao-Li; Fu, Lin; Cheng, Ming-Yu; Yang, Jing-He; Guan, Xin-Xin; Zheng, Xiu-Cheng

2017-12-01

Nitrogen-doped graphene aerogel nanomesh (N-GANM) has been hydrothermally prepared from graphene oxide and ammonium hydroxide using iron nitrate as the etching agent. The results showed that N-GANM with an interesting nanomesh structure on the graphene sheets maintained the 3D architecture of graphene aerogel (GA). Furthermore, it exhibited excellent electrochemical capacitive behavior and the specific capacitance value (290.0 F g-1 at 1 A g-1) remained approximately 90.3% after 2000 cycles in the three-electrode system. In addition, N-GANM displayed an energy density of 30.9 Wh kg-1 at the power density of 450.3 W kg-1 and excellent cycling stability retention (98%) after 10,000 cycles in the two-electrode symmetric device. The resulting N-GANM was expected to be a much favorable supercapacitor electrode material due to the heteroatom-doping and its unique porous structure.

Current applications of graphene oxide in nanomedicine

PubMed Central

Wu, Si-Ying; An, Seong Soo A; Hulme, John

2015-01-01

Graphene has attracted the attention of the entire scientific community due to its unique mechanical and electrochemical, electronic, biomaterial, and chemical properties. The water-soluble derivative of graphene, graphene oxide, is highly prized and continues to be intensely investigated by scientists around the world. This review seeks to provide an overview of the currents applications of graphene oxide in nanomedicine, focusing on delivery systems, tissue engineering, cancer therapies, imaging, and cytotoxicity, together with a short discussion on the difficulties and the trends for future research regarding this amazing material. PMID:26345988

Synthesis, Crystal Structures and Properties of Ferrocenyl Bis-Amide Derivatives Yielded via the Ugi Four-Component Reaction.

PubMed

Zhao, Mei; Shao, Guang-Kui; Huang, Dan-Dan; Lv, Xue-Xin; Guo, Dian-Shun

2017-05-04

Ten ferrocenyl bis-amide derivatives were successfully synthesized via the Ugi four-component reaction by treating ferrocenecarboxylic acid with diverse aldehydes, amines, and isocyanides in methanol solution. Their chemical structures were fully characterized by IR, NMR, HR-MS, and X-ray diffraction analyses. They feature unique molecular morphologies and create a 14-membered ring motif in the centro-symmetric dimers generated in the solid state. Moreover, the electrochemical behavior of these ferrocenyl bis-amides was assessed by cyclic voltammetry.

Electrochemical Performance of Ni-MOFs for Supercapacitors

NASA Astrophysics Data System (ADS)

Li, Yujuan; Song, Lili; Han, Yinghui; Wang, Guangyou

2018-03-01

In this work, the Ni-MOFs of electrode material has been synthesized, characterized and studied for the electrochemical properties of electrode materials. The effects of the doping amount of Ni, calcination temperature and time were studied in detail. The results suggested that the electrochemical properties were obviously improved by the Ni-MOFs of electrode material and the best preparation conditions can also improve the electrochemical properties of electrode materials. These results open a way for the design of tailored MOFs as electrode materials for supercapacitors.

Electrochemistry at Edge of Single Graphene Layer in a Nanopore

PubMed Central

Banerjee, Shouvik; Shim, Jiwook; Rivera, Jose; Jin, Xiaozhong; Estrada, David; Solovyeva, Vita; You, Xiuque; Pak, James; Pop, Eric; Aluru, Narayana; Bashir, Rashid

2013-01-01

We study the electrochemistry of single layer graphene edges using a nanopore-based structure consisting of stacked graphene and Al2O3 dielectric layers. Nanopores, with diameters ranging from 5 to 20 nm, are formed by an electron beam sculpting process on the stacked layers. This leads to unique edge structure which, along with the atomically thin nature of the embedded graphene electrode, demonstrates electrochemical current densities as high as 1.2 × 104 A/cm2. The graphene edge embedded structure offers a unique capability to study the electrochemical exchange at an individual graphene edge, isolated from the basal plane electrochemical activity. We also report ionic current modulation in the nanopore by biasing the embedded graphene terminal with respect to the electrodes in the fluid. The high electrochemical specific current density for a graphene nanopore-based device can have many applications in sensitive chemical and biological sensing, and energy storage devices. PMID:23249127

An InN/InGaN Quantum Dot Electrochemical Biosensor for Clinical Diagnosis

PubMed Central

Alvi, Naveed ul Hassan; Gómez, Victor J.; Rodriguez, Paul E.D. Soto; Kumar, Praveen; Zaman, Saima; Willander, Magnus; Nötzel, Richard

2013-01-01

Low-dimensional InN/InGaN quantum dots (QDs) are demonstrated for realizing highly sensitive and efficient potentiometric biosensors owing to their unique electronic properties. The InN QDs are biochemically functionalized. The fabricated biosensor exhibits high sensitivity of 97 mV/decade with fast output response within two seconds for the detection of cholesterol in the logarithmic concentration range of 1 × 10−6 M to 1 × 10−3 M. The selectivity and reusability of the biosensor are excellent and it shows negligible response to common interferents such as uric acid and ascorbic acid. We also compare the biosensing properties of the InN QDs with those of an InN thin film having the same surface properties, i.e., high density of surface donor states, but different morphology and electronic properties. The sensitivity of the InN QDs-based biosensor is twice that of the InN thin film-based biosensor, the EMF is three times larger, and the response time is five times shorter. A bare InGaN layer does not produce a stable response. Hence, the superior biosensing properties of the InN QDs are governed by their unique surface properties together with the zero-dimensional electronic properties. Altogether, the InN QDs-based biosensor reveals great potential for clinical diagnosis applications. PMID:24132228

Flower-like NiO structures: Controlled hydrothermal synthesis and electrochemical characteristic

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

Chai, Hui; Chen, Xuan; Key Laboratory of Advanced Functional Materials, Institute of Applied Chemistry, Xinjiang University, Urumqi 830046, Xinjiang

Graphical abstract: Flower-like porous NiO was obtained via thermal decomposition of the precursor prepared by a hydrothermal process using hexamethylenetetramine and polyethylene glycol as hydrolysis-controlling agent and surfactant, respectively. The morphology and microstructure of as-synthesized NiO were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results of electrochemical measurements demonstrated that the flower-like porous NiO has high capacity (340 F g{sup −1}) with excellent cycling performance as electrode materials of electrochemical capacitors (ECs), which may be attributed to the unique microstrcture of NiO. Data analyses indicated that NiO with novel porousmore » structure attractive for practical and large-scale applications in electrochemical capacitors. Display Omitted Highlights: ► Synthesis and characterization of NiO with novel porous structure is presented in this work. ► The electrochemical performance of product was examined. ► NiO with excellent performance as electrode materials may be due to the unique microstrcture. ► NiO with novel porous structure attractive for practical with high capacity (340 F g{sup −1}). -- Abstract: Flower-like porous NiO was obtained by thermal decomposition of the precursor prepared by a hydrothermal process with hexamethylenetetramine and polyethylene glycol as hydrolysis-controlling agent and surfactant, respectively. The morphology and microstructure of as-synthesized NiO were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The resulting structures of NiO exhibited porous like petal building blocks. The electrochemical measurements’ results demonstrated that flower-like porous NiO has high capacity (340 F g{sup −1}) with excellent cycling performance as electrode materials for electrochemical capacitors, which may be attributed to the unique structure of NiO. The results indicated that NiO with novel porous structure has been attractive for practical and large-scale applications in electrochemical capacitors.« less

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.

Ionic liquids and derived materials for lithium and sodium batteries.

PubMed

Yang, Qiwei; Zhang, Zhaoqiang; Sun, Xiao-Guang; Hu, Yong-Sheng; Xing, Huabin; Dai, Sheng

2018-03-21

The ever-growing demand for advanced energy storage devices in portable electronics, electric vehicles and large scale power grids has triggered intensive research efforts over the past decade on lithium and sodium batteries. The key to improve their electrochemical performance and enhance the service safety lies in the development of advanced electrode, electrolyte, and auxiliary materials. Ionic liquids (ILs) are liquids consisting entirely of ions near room temperature, and are characterized by many unique properties such as ultralow volatility, high ionic conductivity, good thermal stability, low flammability, a wide electrochemical window, and tunable polarity and basicity/acidity. These properties create the possibilities of designing batteries with excellent safety, high energy/power density and long-term stability, and also provide better ways to synthesize known materials. IL-derived materials, such as poly(ionic liquids), ionogels and IL-tethered nanoparticles, retain most of the characteristics of ILs while being endowed with other favourable features, and thus they have received a great deal of attention as well. This review provides a comprehensive review of the various applications of ILs and derived materials in lithium and sodium batteries including Li/Na-ion, dual-ion, Li/Na-S and Li/Na-air (O 2 ) batteries, with a particular emphasis on recent advances in the literature. Their unique characteristics enable them to serve as advanced resources, medium, or ingredient for almost all the components of batteries, including electrodes, liquid electrolytes, solid electrolytes, artificial solid-electrolyte interphases, and current collectors. Some thoughts on the emerging challenges and opportunities are also presented in this review for further development.

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

Young, Matthias J.; Schnabel, Hans-Dieter; Holder, Aaron M.

Nanoscale spinel lithium manganese oxide is of interest as a high-rate cathode material for advanced battery technologies among other electrochemical applications. In this work, the synthesis of ultrathin films of spinel lithium manganese oxide (LiMn 2O 4) between 20 and 200 nm in thickness by room-temperature electrochemical conversion of MnO grown by atomic layer deposition (ALD) is demonstrated. The charge storage properties of LiMn 2O 4 thin films in electrolytes containing Li +, Na +, K +, and Mg 2+ are investigated. A unified electrochemical band-diagram (UEB) analysis of LiMn 2O 4 informed by screened hybrid density functional theory calculationsmore » is also employed to expand on existing understanding of the underpinnings of charge storage and stability in LiMn 2O 4. It is shown that the incorporation of Li + or other cations into the host manganese dioxide spinel structure (λ-MnO 2) stabilizes electronic states from the conduction band which align with the known redox potentials of LiMn 2O 4. Furthermore, the cyclic voltammetry experiments demonstrate that up to 30% of the capacity of LiMn 2O 4 arises from bulk electronic charge-switching which does not require compensating cation mass transport. As a result, the hybrid ALD-electrochemical synthesis, UEB analysis, and unique charge storage mechanism described here provide a fundamental framework to guide the development of future nanoscale electrode materials for ion-incorporation charge storage.« less

Assembling Hollow Cobalt Sulfide Nanocages Array on Graphene-like Manganese Dioxide Nanosheets for Superior Electrochemical Capacitors.

PubMed

Chen, Hao; Wang, Min Qiang; Yu, Yanan; Liu, Heng; Lu, Shi-Yu; Bao, Shu-Juan; Xu, Maowen

2017-10-11

Metal-organic framework (MOF)-derived hollow cobalt sulfides have attracted extensive attention due to their porous shell that provides rich redox reactions for energy storage. However, their ultradispersed structure and the large size of MOF precursors result in relatively low conductivity, stability, and tap density. Therefore, the construction of an array of continuous hollow cages and tailoring of the inner cavity of MOF-derived materials is very effective for enhancing the electrochemical performance. Herein, we in situ assembled small Co-based zeolitic imidazolate framework (ZIF-67) on the both sides of negatively charged MnO 2 nanosheets to fabricate a hierarchical sandwich-type composite with hollow cobalt sulfide nanocages/graphene-like MnO 2 . The graphene-like MnO 2 nanosheets acted not only as a structure-directing agent to grow a ZIF-67 array but also as a promising electroactive material of electrochemical capacitors to provide capacitance. As an electrode material of supercapacitors, the as-prepared composites exhibit high specific capacitance (1635 F g -1 at 1 A g -1 ), great rate performance (reaching 1160 F g -1 at 10 A g -1 ), and excellent cycling stability (80% retention after 5000 cycles). The outstanding electrochemical properties of our designed materials can be attributed to the unique nanostructure that improved electrical conductivity, created more reactive active sites, and increased the diffusion pathway for electrolyte ions.

Inkjet printing of nanoporous gold electrode arrays on cellulose membranes for high-sensitive paper-like electrochemical oxygen sensors using ionic liquid electrolytes.

PubMed

Hu, Chengguo; Bai, Xiaoyun; Wang, Yingkai; Jin, Wei; Zhang, Xuan; Hu, Shengshui

2012-04-17

A simple approach to the mass production of nanoporous gold electrode arrays on cellulose membranes for electrochemical sensing of oxygen using ionic liquid (IL) electrolytes was established. The approach, combining the inkjet printing of gold nanoparticle (GNP) patterns with the self-catalytic growth of these patterns into conducting layers, can fabricate hundreds of self-designed gold arrays on cellulose membranes within several hours using an inexpensive inkjet printer. The resulting paper-based gold electrode arrays (PGEAs) had several unique properties as thin-film sensor platforms, including good conductivity, excellent flexibility, high integration, and low cost. The porous nature of PGEAs also allowed the addition of electrolytes from the back cellulose membrane side and controllably produced large three-phase electrolyte/electrode/gas interfaces at the front electrode side. A novel paper-based solid-state electrochemical oxygen (O(2)) sensor was therefore developed using an IL electrolyte, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF(6)). The sensor looked like a piece of paper but possessed high sensitivity for O(2) in a linear range from 0.054 to 0.177 v/v %, along with a low detection limit of 0.0075% and a short response time of less than 10 s, foreseeing its promising applications in developing cost-effective and environment-friendly paper-based electrochemical gas sensors.

Electrochemical Quartz Crystal Microbalance with Dissipation Real-Time Hydrodynamic Spectroscopy of Porous Solids in Contact with Liquids.

PubMed

Sigalov, Sergey; Shpigel, Netanel; Levi, Mikhael D; Feldberg, Moshe; Daikhin, Leonid; Aurbach, Doron

2016-10-18

Using multiharmonic electrochemical quartz crystal microbalance with dissipation (EQCM-D) monitoring, a new method of characterization of porous solids in contact with liquids has been developed. The dynamic gravimetric information on the growing, dissolving, or stationary stored solid deposits is supplemented by their precise in-operando porous structure characterization on a mesoscopic scale. We present a very powerful method of quartz-crystal admittance modeling of hydrodynamic solid-liquid interactions in order to extract the porous structure parameters of solids during their formation in real time, using different deposition modes. The unique hydrodynamic spectroscopic characterization of electrolytic and rf-sputtered solid Cu coatings that we use for our "proof of concept" provides a new strategy for probing various electrochemically active thin and thick solid deposits, thereby offering inexpensive, noninvasive, and highly efficient quantitative control over their properties. A broad spectrum of applications of our method is proposed, from various metal electroplating and finishing technologies to deeper insight into dynamic build-up and subsequent development of solid-electrolyte interfaces in the operation of Li-battery electrodes, as well as monitoring hydrodynamic consequences of metal corrosion, and growth of biomass coatings (biofouling) on different solid surfaces in seawater.

Chitosan Biomaterials for Current and Potential Dental Applications

PubMed Central

Husain, Shehriar; Al-Samadani, Khalid H.; Najeeb, Shariq; Zafar, Muhammad S.; Khurshid, Zohaib; Zohaib, Sana; Qasim, Saad B.

2017-01-01

Chitosan (CHS) is a very versatile natural biomaterial that has been explored for a range of bio-dental applications. CHS has numerous favourable properties such as biocompatibility, hydrophilicity, biodegradability, and a broad antibacterial spectrum (covering gram-negative and gram-positive bacteria as well as fungi). In addition, the molecular structure boasts reactive functional groups that provide numerous reaction sites and opportunities for forging electrochemical relationships at the cellular and molecular levels. The unique properties of CHS have attracted materials scientists around the globe to explore it for bio-dental applications. This review aims to highlight and discuss the hype around the development of novel chitosan biomaterials. Utilizing chitosan as a critical additive for the modification and improvement of existing dental materials has also been discussed. PMID:28772963

Biosensing with Förster Resonance Energy Transfer Coupling between Fluorophores and Nanocarbon Allotropes

PubMed Central

Ding, Shaowei; Cargill, Allison A.; Das, Suprem R.; Medintz, Igor L.; Claussen, Jonathan C.

2015-01-01

Nanocarbon allotropes (NCAs), including zero-dimensional carbon dots (CDs), one-dimensional carbon nanotubes (CNTs) and two-dimensional graphene, exhibit exceptional material properties, such as unique electrical/thermal conductivity, biocompatibility and high quenching efficiency, that make them well suited for both electrical/electrochemical and optical sensors/biosensors alike. In particular, these material properties have been exploited to significantly enhance the transduction of biorecognition events in fluorescence-based biosensing involving Förster resonant energy transfer (FRET). This review analyzes current advances in sensors and biosensors that utilize graphene, CNTs or CDs as the platform in optical sensors and biosensors. Widely utilized synthesis/fabrication techniques, intrinsic material properties and current research examples of such nanocarbon, FRET-based sensors/biosensors are illustrated. The future outlook and challenges for the research field are also detailed. PMID:26110411

Tuning the Morphologies of MnO/C Hybrids by Space Constraint Assembly of Mn-MOFs for High Performance Li Ion Batteries.

PubMed

Sun, Dan; Tang, Yougen; Ye, Delai; Yan, Jun; Zhou, Haoshen; Wang, Haiyan

2017-02-15

Morphology controllable fabrication of electrode materials is of great significance but is still a major challenge for constructing advanced Li ion batteries. Herein, we propose a novel space constraint assembly approach to tune the morphology of Mn(terephthalic acid) (PTA)-MOF, in which benzonic acid was employed as a modulator to adjust the available MOF assembly directions. As a result, Mn(PTA)-MOFs with microquadrangulars, microflakes, and spindle-like microrods morphologies have been achieved. MnO/C hybrids with preserved morphologies were further obtained by self-sacrificial and thermal transformation of Mn(PTA)-MOFs. As anodes for Li ion batteries, these morphologies showed great influence on the electrochemical properties. Owing to the abundant porous structure and unique architecture, the MnO/C spindle-like microrods demonstrated superior electrochemical properties with a high reversible capacity of 1165 mAh g -1 at 0.3 A g -1 , excellent rate capability of 580 mAh g -1 at 3 A g -1 , and no considerable capacity loss after 200 cycles at 1 A g -1 . This strategy could be extended to engineering the morphology of other MOF-derived functional materials in various structure-dependent applications.

Improving the performance of lithium-sulfur batteries by graphene coating

NASA Astrophysics Data System (ADS)

Zhou, Xiangyang; Xie, Jing; Yang, Juan; Zou, Youlan; Tang, Jingjing; Wang, Songcan; Ma, Lulu; Liao, Qunchao

2013-12-01

A graphene coating mesoporous carbon/sulfur (RGO@CMK-3/S) composite, which is characteristic of a hybrid structure by incorporating the merits of CMK-3 matrix and graphene (RGO) skin, is synthesized by a facile and scalable route. The CMK-3/S composite is synthesized via a simple melt-diffusion strategy, and then a thin RGO skin is absorbed on the CMK-3/S composite surface in aqueous solution. When evaluating the electrochemical properties of as-prepared RGO wrapped nanostructures as cathode materials in lithium-sulfur batteries, it exhibits much improved cyclical stability and high rate performance. The RGO@CMK-3/S composite with 53.14 wt.% sulfur presents a reversible discharge capacity of about 734 mA h g-1 after 100 cycles at 0.5 C. The improved performance is attributed to the unique structure of RGO@CMK-3/S composite. CMK-3 with extensively mesopores can offer buffering space for the volume change of sulfur and efficient diffusion channel for lithium ions during the charge/discharge process. Meanwhile, the conductive RGO coating skin physically and chemically prevents the dissolution of polysulfides from the cathode, both of which contribute to the reduced capacity fade and improved electrochemical properties.

Electrochemical Properties of Graphene Oxide/Resol Composites as Electrode Materials for Supercapacitor Applications.

PubMed

Park, Geon Woo; Jeon, Sang Kwon; Yang, Jin Yong; Choi, Sung Dae; Kim, Geon Joong

2016-05-01

RGO/Resol carbon composites were prepared from a mixture of reduced GO and a low-molecular-weight phenolic resin (Resol) solution. The effects of the calcination temperature, amount of Resol added and KOH treatment on the electrochemical performance of the RGO/Resol composites were investigated. The physical and electrochemical properties of the composite materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) surface areas measurements, and cyclic voltammetry (CV). The relationships between their physical properties and their electrochemical performance were examined for use as super-capacitors (SCs). The RGO/Resol composite calcined at 400 degrees C after the KOH loading showed dramatically improved electrochemical properties, showing a high BET surface and capacitance of 2190 m2/g and 220 F/g, respectively. The RGO/Resol composites calcined after the KOH treatment showed much better capacitor performance than those treated only thermally at the same temperature without KOH impregnation. The fabrication of high surface electrodes was essential for improving the SCs properties.

Rotaxane and catenane host structures for sensing charged guest species.

PubMed

Langton, Matthew J; Beer, Paul D

2014-07-15

CONSPECTUS: The promise of mechanically interlocked architectures, such as rotaxanes and catenanes, as prototypical molecular switches and shuttles for nanotechnological applications, has stimulated an ever increasing interest in their synthesis and function. The elaborate host cavities of interlocked structures, however, can also offer a novel approach toward molecular recognition: this Account describes the use of rotaxane and catenane host systems for binding charged guest species, and for providing sensing capability through an integrated optical or electrochemical reporter group. Particular attention is drawn to the exploitation of the unusual dynamic properties of interlocked molecules, such as guest-induced shuttling or conformational switching, as a sophisticated means of achieving a selective and functional sensor response. We initially survey interlocked host systems capable of sensing cationic guests, before focusing on our accomplishments in synthesizing rotaxanes and catenanes designed for the more challenging task of selective anion sensing. In our group, we have developed the use of discrete anionic templation to prepare mechanically interlocked structures for anion recognition applications. Removal of the anion template reveals an interlocked host system, possessing a unique three-dimensional geometrically restrained binding cavity formed between the interlocked components, which exhibits impressive selectivity toward complementary anionic guest species. By incorporating reporter groups within such systems, we have developed both electrochemical and optical anion sensors which can achieve highly selective sensing of anionic guests. Transition metals, lanthanides, and organic fluorophores integrated within the mechanically bonded structural framework of the receptor are perturbed by the binding of the guest, with a concomitant change in the emission profile. We have also exploited the unique dynamics of interlocked hosts by demonstrating that an anion-induced conformational change can be used as a means of signal transduction. Electrochemical sensing has been realized by integration of the redox-active ferrocene functionality within a range of rotaxane and catenanes; binding of an anion perturbs the metallocene, leading to a cathodic shift in the ferrocene/ferrocenium redox couple. In order to obtain practical sensors for target charged guest species, confinement of receptors at a surface is necessary in order to develop robust, reuseable devices. Surface confinement also offers advantages over solution based receptors, including amplification of signal, enhanced guest binding thermodynamics and the negation of solubility problems. We have fabricated anion-templated rotaxanes and catenanes on gold electrode surfaces and demonstrated that the resulting mechanically bonded self-assembled monolayers are electrochemically responsive to the binding of anions, a crucial first step toward the advancement of sophisticated, highly selective, anion sensory devices. Rotaxane and catenane host molecules may be engineered to offer a superior level of molecular recognition, and the incorporation of optical or electrochemical reporter groups within these interlocked frameworks can allow for guest sensing. Advances in synthetic templation strategies has facilitated the synthesis of interlocked architectures and widened their interest as prototype molecular machines. However, their unique host-guest properties are only now beginning to be exploited as a sophisticated approach to chemical sensing. The development of functional host-guest sensory systems such as these is of great interest to the interdisciplinary field of supramolecular chemistry.

High loading MnO2 nanowires on graphene paper: facile electrochemical synthesis and use as flexible electrode for tracking hydrogen peroxide secretion in live cells.

PubMed

Dong, Shuang; Xi, Jiangbo; Wu, Yanan; Liu, Hongwei; Fu, Chaoyang; Liu, Hongfang; Xiao, Fei

2015-01-01

Recent progress in flexible and lightweight electrochemical sensor systems requires the development of paper-like electrode materials. Here, we report a facile and green synthesis of a new type of MnO2 nanowires-graphene nanohybrid paper by one-step electrochemical method. This strategy demonstrates a collection of unique features including the effective electrochemical reduction of graphene oxide (GO) paper and the high loading of MnO2 nanowires on electrochemical reduced GO (ERGO) paper. When used as flexible electrode for nonenzymatic detection of hydrogen peroxide (H2O2), MnO2-ERGO paper exhibits high electrocatalytic activity toward the redox of H2O2 as well as excellent stability, selectivity and reproducibility. The amperometric responses are linearly proportional to H2O2 concentration in the range 0.1-45.4 mM, with a detection limit of 10 μM (S/N=3) and detection sensitivity of 59.0 μA cm(-2) mM(-1). These outstanding sensing performances enable the practical application of MnO2-ERGO paper electrode for the real-time tracking H2O2 secretion by live cells macrophages. Therefore, the proposed graphene-based nanohybrid paper electrode with intrinsic flexibility, tailorable shapes and adjustable properties can contribute to the full realization of high-performance flexible electrode material used in point-of-care testing devices and portable instruments for in-vivo clinical diagnostics and on-site environmental monitoring. Copyright © 2014 Elsevier B.V. All rights reserved.

Band diagram and rate analysis of thin film spinel LiMn 2O 4 formed by electrochemical conversion of ALD-grown MnO

DOE PAGES

Young, Matthias J.; Schnabel, Hans-Dieter; Holder, Aaron M.; ...

2016-09-22

Nanoscale spinel lithium manganese oxide is of interest as a high-rate cathode material for advanced battery technologies among other electrochemical applications. In this work, the synthesis of ultrathin films of spinel lithium manganese oxide (LiMn 2O 4) between 20 and 200 nm in thickness by room-temperature electrochemical conversion of MnO grown by atomic layer deposition (ALD) is demonstrated. The charge storage properties of LiMn 2O 4 thin films in electrolytes containing Li +, Na +, K +, and Mg 2+ are investigated. A unified electrochemical band-diagram (UEB) analysis of LiMn 2O 4 informed by screened hybrid density functional theory calculationsmore » is also employed to expand on existing understanding of the underpinnings of charge storage and stability in LiMn 2O 4. It is shown that the incorporation of Li + or other cations into the host manganese dioxide spinel structure (λ-MnO 2) stabilizes electronic states from the conduction band which align with the known redox potentials of LiMn 2O 4. Furthermore, the cyclic voltammetry experiments demonstrate that up to 30% of the capacity of LiMn 2O 4 arises from bulk electronic charge-switching which does not require compensating cation mass transport. As a result, the hybrid ALD-electrochemical synthesis, UEB analysis, and unique charge storage mechanism described here provide a fundamental framework to guide the development of future nanoscale electrode materials for ion-incorporation charge storage.« less

Immunosensor based on electrodeposition of gold-nanoparticles and ionic liquid composite for detection of Salmonella pullorum.

PubMed

Wang, Dan; Dou, Wenchao; Zhao, Guangying; Chen, Yan

2014-11-01

In order to increase the reproducibility and stability of electrochemical immunosensor, which is a key issue for its application and popularization, an accurate and stable immunosensor for rapid detection of Salmonella pullorum (S. pullorum) was proposed in this study. The immunosensor was fabricated by modifying Screen-printed Carbon Electrode (SPCE) with electrodeposited gold nanoparticles (AuNPs), HRP-labeled anti-S. pullorum and ionic liquids (ILs) (AuNP/HRP/IL). AuNPs are electrodeposited on the working electrode surface to increase the amount of antibodies that bind to the electrode and then modified with ILs to protect the antibodies from being inactivated in the test environment and maintain their biological activity and the stability of the detection electrode. The electrochemical characteristics of the stepwise modified electrodes and the detection of S. pullorum were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). As shown in the results of the experiments, AuNPs with unique electrochemical properties as well as biocompatibility characteristics have been proven to be able to strengthen the antibody combination effectively and to increase the electrochemical response signal. In addition, a crucial assessment regarding implementation of stability and reproducibility analysis of a range of immunosensors is provided. We found that application of AuNPs/ILs in the immune modified electrodes showed obvious improvement when compared with other groups. Given their high levels of reproducibility, stability, target specificity and sensitivity, AuNPs and ILs were considered to be excellent elements for electrode modification. Copyright © 2014 Elsevier B.V. All rights reserved.

Rapid biosensing tools for cancer biomarkers.

PubMed

Ranjan, Rajeev; Esimbekova, Elena N; Kratasyuk, Valentina A

2017-01-15

The present review critically discusses the latest developments in the field of smart diagnostic systems for cancer biomarkers. A wide coverage of recent biosensing approaches involving aptamers, enzymes, DNA probes, fluorescent probes, interacting proteins and antibodies in vicinity to transducers such as electrochemical, optical and piezoelectric is presented. Recent advanced developments in biosensing approaches for cancer biomarker owes much credit to functionalized nanomaterials due to their unique opto-electronic properties and enhanced surface to volume ratio. Biosensing methods for a plenty of cancer biomarkers has been summarized emphasizing the key principles involved. Copyright © 2016 Elsevier B.V. All rights reserved.

Demonstration of Electrochemical Cell Properties by a Simple, Colorful Oxidation-reduction Experiment.

ERIC Educational Resources Information Center

Hendricks, Lloyd J.; And Others

1982-01-01

Describes apparatus/methodology and provides background information for an experiment demonstrating electrochemical concepts and properties of electrochemical cells. The color of a solution close to an electrode is changed from that of the bulk solution to either of two contrasting colors depending on whether the reaction is oxidation or…

Concepts for smart nanocomposite materials

NASA Astrophysics Data System (ADS)

Pammi, SriLaxmi; Brown, Courtney; Datta, Saurabh; Kirikera, Goutham R.; Schulz, Mark J.

2003-10-01

This paper explores concepts for new smart materials that have extraordinary properties based on nanotechnology. Carbon and boron nitride nanotubes in theory can be used to manufacture fibers that have piezoelectric, pyroelectric, piezoresistive, and electrochemical field properties. Smart nanocomposites designed using these fibers will sense and respond to elastic, thermal, and chemical fields in a positive human-like way to improve the performance of structures, devices, and possibly humans. Remarkable strength, morphing, cooling, energy harvesting, strain and temperature sensing, chemical sensing and filtering, and high natural frequencies and damping will be the properties of these new materials. Synthesis of these unique atomically precise nanotubes, fibers, and nanocomposites is at present challenging and expensive, however, there is the possibility that we can synthesize the strongest and lightest actuators and most efficient sensors man has ever made. A particular advantage of nanotube transducers is their very high load bearing capability. Carbon nanotube electrochemical actuators have a predicted energy density at low frequencies that is thirty times greater than typical piezoceramic materials while boron nitride nanotubes are insulators and can operate at high temperatures, but they have a predicted piezoelectric induced stress constant that is about twenty times smaller than piezoceramic materials. Carbon nanotube fibers and composites exhibit a change in electrical conductivity due to strain that can be used for sensing. Some concepts for nanocomposite material sensors are presented and initial efforts to fabricate carbon nanocomposite load sensors are discussed.

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.

Electrochemical properties of titanium nitride nerve stimulation electrodes: an in vitro and in vivo study

PubMed Central

Meijs, Suzan; Fjorback, Morten; Jensen, Carina; Sørensen, Søren; Rechendorff, Kristian; Rijkhoff, Nico J. M.

2015-01-01

The in vivo electrochemical behavior of titanium nitride (TiN) nerve stimulation electrodes was compared to their in vitro behavior for a period of 90 days. Ten electrodes were implanted in two Göttingen minipigs. Four of these were used for electrical stimulation and electrochemical measurements. Five electrodes were kept in Ringer's solution at 37.5°C, of which four were used for electrical stimulation and electrochemical measurements. The voltage transients measured in vivo were 13 times greater than in vitro at implantation and they continued to increase with time. The electrochemical properties in vivo and the tissue resistance (Rtissue) followed a similar trend with time. There was no consistent significant difference between the electrochemical properties of the in vivo and in vitro electrodes after the implanted period. The differences between the in vivo and in vitro electrodes during the implanted period show that the evaluation of electrochemical performance of implantable stimulation electrodes cannot be substituted with in vitro measurements. After the implanted period, however, the performance of the in vivo and in vitro electrodes in saline was similar. In addition, the changes observed over time during the post-implantation period regarding the electrochemical properties of the in vivo electrodes and Rtissue were similar, which indicates that these changes are due to the foreign body response to implantation. PMID:26300717

Pyro-Synthesis of Functional Nanocrystals

PubMed Central

Gim, Jihyeon; Mathew, Vinod; Lim, Jinsub; Song, Jinju; Baek, Sora; Kang, Jungwon; Ahn, Docheon; Song, Sun-Ju; Yoon, Hyeonseok; Kim, Jaekook

2012-01-01

Despite nanomaterials with unique properties playing a vital role in scientific and technological advancements of various fields including chemical and electrochemical applications, the scope for exploration of nano-scale applications is still wide open. The intimate correlation between material properties and synthesis in combination with the urgency to enhance the empirical understanding of nanomaterials demand the evolution of new strategies to promising materials. Herein we introduce a rapid pyro-synthesis that produces highly crystalline functional nanomaterials under reaction times of a few seconds in open-air conditions. The versatile technique may facilitate the development of a variety of nanomaterials and, in particular, carbon-coated metal phosphates with appreciable physico-chemical properties benefiting energy storage applications. The present strategy may present opportunities to develop “design rules” not only to produce nanomaterials for various applications but also to realize cost-effective and simple nanomaterial production beyond lab-scale limitations. PMID:23230511

Pyro-synthesis of functional nanocrystals.

PubMed

Gim, Jihyeon; Mathew, Vinod; Lim, Jinsub; Song, Jinju; Baek, Sora; Kang, Jungwon; Ahn, Docheon; Song, Sun-Ju; Yoon, Hyeonseok; Kim, Jaekook

2012-01-01

Despite nanomaterials with unique properties playing a vital role in scientific and technological advancements of various fields including chemical and electrochemical applications, the scope for exploration of nano-scale applications is still wide open. The intimate correlation between material properties and synthesis in combination with the urgency to enhance the empirical understanding of nanomaterials demand the evolution of new strategies to promising materials. Herein we introduce a rapid pyro-synthesis that produces highly crystalline functional nanomaterials under reaction times of a few seconds in open-air conditions. The versatile technique may facilitate the development of a variety of nanomaterials and, in particular, carbon-coated metal phosphates with appreciable physico-chemical properties benefiting energy storage applications. The present strategy may present opportunities to develop "design rules" not only to produce nanomaterials for various applications but also to realize cost-effective and simple nanomaterial production beyond lab-scale limitations.

Shape-Tailorable Graphene-Based Ultra-High-Rate Supercapacitor for Wearable Electronics.

PubMed

Xie, Binghe; Yang, Cheng; Zhang, Zhexu; Zou, Peichao; Lin, Ziyin; Shi, Gaoquan; Yang, Quanhong; Kang, Feiyu; Wong, Ching-Ping

2015-06-23

With the bloom of wearable electronics, it is becoming necessary to develop energy storage units, e.g., supercapacitors that can be arbitrarily tailored at the device level. Although gel electrolytes have been applied in supercapacitors for decades, no report has studied the shape-tailorable capability of a supercapacitor, for instance, where the device still works after being cut. Here we report a tailorable gel-based supercapacitor with symmetric electrodes prepared by combining electrochemically reduced graphene oxide deposited on a nickel nanocone array current collector with a unique packaging method. This supercapacitor with good flexibility and consistency showed excellent rate performance, cycling stability, and mechanical properties. As a demonstration, these tailorable supercapacitors connected in series can be used to drive small gadgets, e.g., a light-emitting diode (LED) and a minimotor propeller. As simple as it is (electrochemical deposition, stencil printing, etc.), this technique can be used in wearable electronics and miniaturized device applications that require arbitrarily shaped energy storage units.

Mesoporous TiO2 nanosheets anchored on graphene for ultra long life Na-ion batteries.

PubMed

Zhang, Ruifang; Wang, Yuankun; Zhou, Han; Lang, Jinxin; Xu, Jingjing; Xiang, Yang; Ding, Shujiang

2018-06-01

Sodium-ion batteries, which have a similar electrochemical reaction mechanism to lithium-ion batteries, have been considered as one of the most potential lithium-ion battery alternatives due to the rich reserves of sodium. However, it is very hard to find appropriate electrode materials imputing the large radius of sodium-ion. TiO 2 is particularly interesting as anodes for sodium-ion batteries due to their reasonable operation voltage, cost, and nontoxicity. To obtain a better electrochemical property, mesoporous TiO 2 nanosheets (NSs)/reduced graphene oxide (rGO) composites have been synthesized via a scalable hydrothermal-solvothermal method with a subsequent calcination process. Benefitting from unique structure design, TiO 2 NSs@rGO exhibits a superior cycle stability (90 mAh g -1 after 10 000 cycles at a high current rate of 20 C) and satisfactory rate performance (97.3 mAh g -1 at 25 C). To our knowledge, such ultra long cycle life has not previously been reported.

Carbon-coated nanoparticle superlattices for energy applications

NASA Astrophysics Data System (ADS)

Li, Jun; Yiliguma, Affa; Wang, Yifei; Zheng, Gengfeng

2016-07-01

Nanoparticle (NP) superlattices represent a unique material architecture for energy conversion and storage. Recent reports on carbon-coated NP superlattices have shown exciting electrochemical properties attributed to their rationally designed compositions and structures, fast electron transport, short diffusion length, and abundant reactive sites via enhanced coupling between close-packed NPs, which are distinctive from their isolated or disordered NP or bulk counterparts. In this minireview, we summarize the recent developments of highly-ordered and interconnected carbon-coated NP superlattices featuring high surface area, tailorable and uniform doping, high conductivity, and structure stability. We then introduce the precisely-engineered NP superlattices by tuning/studying specific aspects, including intermetallic structures, long-range ordering control, and carbon coating methods. In addition, these carbon-coated NP superlattices exhibit promising characteristics in energy-oriented applications, in particular, in the fields of lithium-ion batteries, fuel cells, and electrocatalysis. Finally, the challenges and perspectives are discussed to further explore the carbon-coated NP superlattices for optimized electrochemical performances.

Self-Assembled Protein Nanofilter for Trapping Polysulfides and Promoting Li+ Transport in Lithium-Sulfur Batteries.

PubMed

Fu, Xuewei; Li, Chunhui; Wang, Yu; Scudiero, Louis; Liu, Jin; Zhong, Wei-Hong

2018-05-17

The diffusion of polysulfides in lithium-sulfur (Li-S) batteries represents a critical issue deteriorating the electrochemical performance. Here, borrowing the concepts from air filtration, we design and fabricate a protein-based nanofilter for effectively trapping polysulfides but facilitating Li + transport. The unique porous structures are formed through a protein-directed self-assembly process, and the surfaces are functionalized by the protein residues. The experiments and molecular simulation results demonstrate that our polysulfide nanofilter can effectively trap the dissolved polysulfides and promote Li + transport in Li-S batteries. When the polysulfide nanofilter is added in a Li-S battery, the electrochemical performance of the battery is significantly improved. Moreover, the contribution of the protein nanofilter to the ion transport is further analyzed by correlating filter properties and battery performance. This study is of universal significance for the understanding, design, and fabrication of advanced battery interlayers that can help realize good management of the ion transport inside advanced energy storage devices.

Novel amperometric glucose biosensor based on MXene nanocomposite.

PubMed

Rakhi, R B; Nayak, Pranati; Xia, Chuan; Alshareef, Husam N

2016-11-10

A biosensor platform based on Au/MXene nanocomposite for sensitive enzymatic glucose detection is reported. The biosensor leverages the unique electrocatalytic properties and synergistic effects between Au nanoparticles and MXene sheets. An amperometric glucose biosensor is fabricated by the immobilization of glucose oxidase (GOx) enzyme on Nafion solubilized Au/ MXene nanocomposite over glassy carbon electrode (GCE). The biomediated Au nanoparticles play a significant role in facilitating the electron exchange between the electroactive center of GOx and the electrode. The GOx/Au/MXene/Nafion/GCE biosensor electrode displayed a linear amperometric response in the glucose concentration range from 0.1 to 18 mM with a relatively high sensitivity of 4.2 μAmM -1 cm -2 and a detection limit of 5.9 μM (S/N = 3). Furthermore, the biosensor exhibited excellent stability, reproducibility and repeatability. Therefore, the Au/MXene nanocomposite reported in this work is a potential candidate as an electrochemical transducer in electrochemical biosensors.

One-step synthesis of 3D sulfur/nitrogen dual-doped graphene supported nano silicon as anode for Li-ion batteries

NASA Astrophysics Data System (ADS)

Li, Ruihong; Li, Junli; Qi, Kaiyu; Ge, Xin; Zhang, Qiwei; Zhang, Bangwen

2018-03-01

Silicon is one of the most promising candidates for next-generation anode of Lithium-ion batteries. However, poor electrical conductivity and large volume change during alloying/dealloying hinder its practical use. Here we reported a three-dimensional (3D) nitrogen and sulfur codoped graphene supported silicon nanoparticles composite (SN-G/Si) through one-step hydrothermal self-assembly. The obtained SN-G/Si was investigated in term of instrumental characterizations and electrochemical properties. The results show that SN-G/Si as a freestanding anode in LIBs delivers a reversible capacity of 2020 mAh g-1 after 100 cycles with coulombic efficiency of nearly 97%. The excellent electrochemical performance is associated with the unique structure and the synergistic effect of SN-G/Si, in which SN-G provides volume buffer for nano Si as the flexible loader, short paths/fast channels for electron/Li ion transport as porous skeleton, and low charge-transfer resistance.

Mesoporous TiO2 nanosheets anchored on graphene for ultra long life Na-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Ruifang; Wang, Yuankun; Zhou, Han; Lang, Jinxin; Xu, Jingjing; Xiang, Yang; Ding, Shujiang

2018-06-01

Sodium-ion batteries, which have a similar electrochemical reaction mechanism to lithium-ion batteries, have been considered as one of the most potential lithium-ion battery alternatives due to the rich reserves of sodium. However, it is very hard to find appropriate electrode materials imputing the large radius of sodium-ion. TiO2 is particularly interesting as anodes for sodium-ion batteries due to their reasonable operation voltage, cost, and nontoxicity. To obtain a better electrochemical property, mesoporous TiO2 nanosheets (NSs)/reduced graphene oxide (rGO) composites have been synthesized via a scalable hydrothermal-solvothermal method with a subsequent calcination process. Benefitting from unique structure design, TiO2 NSs@rGO exhibits a superior cycle stability (90 mAh g‑1 after 10 000 cycles at a high current rate of 20 C) and satisfactory rate performance (97.3 mAh g‑1 at 25 C). To our knowledge, such ultra long cycle life has not previously been reported.

Novel amperometric glucose biosensor based on MXene nanocomposite

PubMed Central

Rakhi, R. B.; Nayuk, Pranati; Xia, Chuan; Alshareef, Husam N.

2016-01-01

A biosensor platform based on Au/MXene nanocomposite for sensitive enzymatic glucose detection is reported. The biosensor leverages the unique electrocatalytic properties and synergistic effects between Au nanoparticles and MXene sheets. An amperometric glucose biosensor is fabricated by the immobilization of glucose oxidase (GOx) enzyme on Nafion solubilized Au/ MXene nanocomposite over glassy carbon electrode (GCE). The biomediated Au nanoparticles play a significant role in facilitating the electron exchange between the electroactive center of GOx and the electrode. The GOx/Au/MXene/Nafion/GCE biosensor electrode displayed a linear amperometric response in the glucose concentration range from 0.1 to 18 mM with a relatively high sensitivity of 4.2 μAmM−1 cm−2 and a detection limit of 5.9 μM (S/N = 3). Furthermore, the biosensor exhibited excellent stability, reproducibility and repeatability. Therefore, the Au/MXene nanocomposite reported in this work is a potential candidate as an electrochemical transducer in electrochemical biosensors. PMID:27830757

Quasi-Dual-Packed-Kerneled Au49 (2,4-DMBT)27 Nanoclusters and the Influence of Kernel Packing on the Electrochemical Gap.

PubMed

Liao, Lingwen; Zhuang, Shengli; Wang, Pu; Xu, Yanan; Yan, Nan; Dong, Hongwei; Wang, Chengming; Zhao, Yan; Xia, Nan; Li, Jin; Deng, Haiteng; Pei, Yong; Tian, Shi-Kai; Wu, Zhikun

2017-10-02

Although face-centered cubic (fcc), body-centered cubic (bcc), hexagonal close-packed (hcp), and other structured gold nanoclusters have been reported, it was unclear whether gold nanoclusters with mix-packed (fcc and non-fcc) kernels exist, and the correlation between kernel packing and the properties of gold nanoclusters is unknown. A Au 49 (2,4-DMBT) 27 nanocluster with a shell electron count of 22 has now been been synthesized and structurally resolved by single-crystal X-ray crystallography, which revealed that Au 49 (2,4-DMBT) 27 contains a unique Au 34 kernel consisting of one quasi-fcc-structured Au 21 and one non-fcc-structured Au 13 unit (where 2,4-DMBTH=2,4-dimethylbenzenethiol). Further experiments revealed that the kernel packing greatly influences the electrochemical gap (EG) and the fcc structure has a larger EG than the investigated non-fcc structure. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Younesi, Reza; Veith, Gabriel M.; Johansson, Patrik

Presently lithium hexafluorophosphate (LiPF 6) is the dominant Li-salt used in commercial rechargeable lithium-ion batteries (LIBs) based on a graphite anode and a 3-4 V cathode material. While LiPF 6 is not the ideal Li-salt for every important electrolyte property, it has a uniquely suitable combination of properties (temperature range, passivation, conductivity, etc.) rendering it the overall best Li-salt for LIBs. However, this may not necessarily be true for other types of Li-based batteries. Indeed, next generation batteries, for example lithium-metal (Li-metal), lithium-oxygen (Li-O 2), and lithium sulphur (Li-S), require a re-evaluation of Li-salts due to the different electrochemical andmore » chemical reactions and conditions within such cells. Furthermore, this review explores the critical role Li-salts play in ensuring in these batteries viability.« less

An introductory study using impedance spectroscopy technique with polarizable microelectrode for amino acids characterization

NASA Astrophysics Data System (ADS)

Chin, K. B.; Chi, I.; Pasalic, J.; Huang, C.-K.; Barge, Laura M.

2018-04-01

Portable, low power, yet ultra-sensitive life detection instrumentations are vital to future astrobiology flight programs at NASA. In this study, initial attempts to characterize amino acids in an aqueous environment by electrochemical impedance spectroscopy (EIS) using polarizable (blocking) electrodes in order to establish a means of detection via their electrical properties. Seven amino acids were chosen due to their scientific importance in demonstrating sensitivity levels in the range of part per billion concentration. Albeit more challenging in real systems of analyst mixtures, we found individual amino acids in aqueous environment do exhibit some degree of chemical and physical uniqueness to warrant characterization by EIS. The polar amino acids (Asp, Glu, and His) exhibited higher electrochemical activity than the non-polar amino acids (Ala, Gly, Val, and Leu). The non-polar amino acids (Gly and Ala) also exhibited unique electrical properties which appeared to be more dependent on physical characteristics such as molecular weight and structure. At concentrations above 1 mM where the amino acids play a more dominant transport role within the water, the conductivity was found to be more sensitive to concentrations. At lower concentrations <1 mM, however, the polar amino acid solution conductivity remained constant, suggesting poor chemical activity with water. As revealed by equivalent circuit modeling, the relaxation times showed a 1-2 order of magnitude difference between polar and non-polar amino acids. The pseudo-capacitance from EIS measurements on sample mixtures containing salt water and individual amino acids revealed the possibility for improvement in amino acid selectivity using gold nanoporous surface enhanced electrodes. This work establishes important methodologies for characterizing amino acids using EIS combined with microscale electrodes, supporting the case for instrumentation development for life detection and origin of life programs.

An introductory study using impedance spectroscopy technique with polarizable microelectrode for amino acids characterization.

PubMed

Chin, K B; Chi, I; Pasalic, J; Huang, C-K; Barge, Laura M

2018-04-01

Portable, low power, yet ultra-sensitive life detection instrumentations are vital to future astrobiology flight programs at NASA. In this study, initial attempts to characterize amino acids in an aqueous environment by electrochemical impedance spectroscopy (EIS) using polarizable (blocking) electrodes in order to establish a means of detection via their electrical properties. Seven amino acids were chosen due to their scientific importance in demonstrating sensitivity levels in the range of part per billion concentration. Albeit more challenging in real systems of analyst mixtures, we found individual amino acids in aqueous environment do exhibit some degree of chemical and physical uniqueness to warrant characterization by EIS. The polar amino acids (Asp, Glu, and His) exhibited higher electrochemical activity than the non-polar amino acids (Ala, Gly, Val, and Leu). The non-polar amino acids (Gly and Ala) also exhibited unique electrical properties which appeared to be more dependent on physical characteristics such as molecular weight and structure. At concentrations above 1 mM where the amino acids play a more dominant transport role within the water, the conductivity was found to be more sensitive to concentrations. At lower concentrations <1 mM, however, the polar amino acid solution conductivity remained constant, suggesting poor chemical activity with water. As revealed by equivalent circuit modeling, the relaxation times showed a 1-2 order of magnitude difference between polar and non-polar amino acids. The pseudo-capacitance from EIS measurements on sample mixtures containing salt water and individual amino acids revealed the possibility for improvement in amino acid selectivity using gold nanoporous surface enhanced electrodes. This work establishes important methodologies for characterizing amino acids using EIS combined with microscale electrodes, supporting the case for instrumentation development for life detection and origin of life programs.

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.

Structure, Electronic Properties, and Electrochemical Behavior of a Boron-Doped Diamond/Quartz Optically Transparent Electrode.

PubMed

Wächter, Naihara; Munson, Catherine; Jarošová, Romana; Berkun, Isil; Hogan, Timothy; Rocha-Filho, Romeu C; Swain, Greg M

2016-10-26

The morphology, microstructure, chemistry, electronic properties, and electrochemical behavior of a boron-doped nanocrystalline diamond (BDD) thin film grown on quartz were evaluated. Diamond optically transparent electrodes (OTEs) are useful for transmission spectroelectrochemical measurements, offering excellent stability during anodic and cathodic polarization and exposure to a variety of chemical environments. We report on the characterization of a BDD OTE by atomic force microscopy, optical spectroscopy, Raman spectroscopic mapping, alternating-current Hall effect measurements, X-ray photoelectron spectroscopy, and electrochemical methods. The results reported herein provide the first comprehensive study of the relationship between the physical and chemical structure and electronic properties of a diamond OTE and the electrode's electrochemical activity.

Synthesis and Electrochemical Properties Characterization of SnO2-coated LiNi1/3Co1/3Mn1/3O2 Cathode Material for Lithium Ion Batteries

DTIC Science & Technology

2009-01-01

Synthesis and electrochemical properties characterization of SnO2-coated LiNi1/3Co1/3Mn1/3O2 cathode material for lithium ion batteries Ping Yang...electrochemical properties characterization of SnO2-coated LiNi1/3Co1/3Mn1/3O2 cathode material for lithium ion batteries 5a. CONTRACT NUMBER 5b. GRANT NUMBER...electrochemical reaction. References 1. N Yabuuchi, T Ohzuku, “Novel lithium insertion material of LiCo1/3Ni1/3Mn1/3O2 for advanced lithium - ion batteries ”, J

Next-Generation Electrochemical Energy Materials for Intermediate Temperature Molten Oxide Fuel Cells and Ion Transport Molten Oxide Membranes.

PubMed

Belousov, Valery V

2017-02-21

High temperature electrochemical devices such as solid oxide fuel cells (SOFCs) and oxygen separators based on ceramic materials are used for efficient energy conversion. These devices generally operate in the temperature range of 800-1000 °C. The high operating temperatures lead to accelerated degradation of the SOFC and oxygen separator materials. To solve this problem, the operating temperatures of these electrochemical devices must be lowered. However, lowering the temperature is accompanied by decreasing the ionic conductivity of fuel cell electrolyte and oxygen separator membrane. Therefore, there is a need to search for alternative electrolyte and membrane materials that have high ionic conductivity at lower temperatures. A great many opportunities exist for molten oxides as electrochemical energy materials. Because of their unique electrochemical properties, the molten oxide innovations can offer significant benefits for improving energy efficiency. In particular, the newly developed electrochemical molten oxide materials show high ionic conductivities at intermediate temperatures (600-800 °C) and could be used in molten oxide fuel cells (MOFCs) and molten oxide membranes (MOMs). The molten oxide materials containing both solid grains and liquid channels at the grain boundaries have advantages compared to the ceramic materials. For example, the molten oxide materials are ductile, which solves a problem of thermal incompatibility (difference in coefficient of thermal expansion, CTE). Besides, the outstanding oxygen selectivity of MOM materials allows us to separate ultrahigh purity oxygen from air. For their part, the MOFC electrolytes show the highest ionic conductivity at intermediate temperatures. To evaluate the potential of molten oxide materials for technological applications, the relationship between the microstructure of these materials and their transport and mechanical properties must be revealed. This Account summarizes the latest results on oxygen ion transport in potential MOM materials and MOFC electrolytes. In addition, we consider the rapid oxygen transport in a molten oxide scale formed on a metal surface during catastrophic oxidation and show that the same transport could be used beneficially in MOMs and MOFCs. A polymer model explaining the oxygen transport in molten oxides is also considered. Understanding the oxygen transport mechanisms in oxide melts is important for the development of new generation energy materials, which will contribute to more efficient operation of electrochemical devices at intermediate temperatures. Here we highlight the progress made in developing this understanding. We also show the latest advances made in search of alternative molten oxide materials having high mixed ion electronic and ionic conductivities for use in MOMs and MOFCs, respectively. Prospects for further research are presented.

Flexible nanohybrid microelectrode based on carbon fiber wrapped by gold nanoparticles decorated nitrogen doped carbon nanotube arrays: In situ electrochemical detection in live cancer cells.

PubMed

Zhang, Yan; Xiao, Jian; Sun, Yimin; Wang, Lu; Dong, Xulin; Ren, Jinghua; He, Wenshan; Xiao, Fei

2018-02-15

The rapidly growing demand for in situ real-time monitoring of chemical information in vitro and in vivo has attracted tremendous research efforts into the design and construction of high-performance biosensor devices. Herein, we develop a new type of flexible nanohybrid microelectrode based on carbon fiber wrapped by gold nanoparticles decorated nitrogen-doped carbon nanotube arrays, and explore its practical application in in situ electrochemical detection of cancer biomarker H 2 O 2 secreted from live cancer cells. Our results demonstrate that carbon fiber material with microscale size and fascinating mechanical properties can be used as a robust and flexible microelectrode substrate in the electrochemical biosensor system. And the highly ordered nitrogen-doped carbon nanotube arrays that grown on carbon fiber possess high surface area-to-volume ratio and abundant active sites, which facilitate the loading of high-density and uniformly dispersed gold nanoparticles on it. Benefited from the unique microstructure and excellent electrocatalytic properties of different components in the nanohybrid fiber microelectrode, an effective electrochemical sensing platform based on it has been built up for the sensitive and selective detection of H 2 O 2 , the detection limit is calculated to be 50nM when the signal-to-noise ratio is 3:1, and the linear dynamic range is up to 4.3mM, with a high sensitivity of 142µAcm -2 mM -1 . These good sensing performances, coupled with its intrinsic mechanical flexibility and biocompatibility, allow for its use in in situ real-time tracking H 2 O 2 secreted from breast cancer cell lines MCF-7 and MBA-MD-231, and evaluating the sensitivity of different cancer cells to chemotherapy or radiotherapy treatments, which hold great promise for clinic application in cancer diagnose and management. Copyright © 2017 Elsevier B.V. All rights reserved.

Fundamental Properties of One-Dimensional Zinc Oxide Nanomaterials and Implementations in Various Detection Modes of Enhanced Biosensing

PubMed Central

Hahm, Jong-in

2016-01-01

Recent bioapplications of one-dimensional (1D) zinc oxide (ZnO) nanomaterials, despite the short development period, have shown promising signs as new sensors and assay platforms offering exquisite biomolecular sensitivity and selectivity. The incorporation of 1D ZnO nanomaterials has proven beneficial to various modes of biodetection owing to their inherent properties. The more widely explored electrochemical and electrical approaches tend to capitalize on the reduced physical dimensionality, yielding a high surface-to-volume ratio, as well as on the electrical properties of ZnO. The newer development of the use of 1D ZnO nanomaterials in fluorescence-based biodetection exploits the innate optical property of their high anisotropy. This review considers stimulating research advances made to identify and understand fundamental properties of 1D ZnO nanomaterials, and examines various biosensing modes utilizing them, while focusing on the unique optical properties of individual and ensembles of 1D ZnO nanomaterials specifically pertaining to their bio-optical applications in simple and complex fluorescence assays. PMID:27215822

Study on the electrochemical properties of cubic ordered mesoporous carbon for supercapacitors

NASA Astrophysics Data System (ADS)

Lang, Jun-Wei; Yan, Xing-Bin; Yuan, Xiao-Yan; Yang, Jie; Xue, Qun-Ji

Highly ordered, three-dimensional (3D) cubic mesoporous carbon CMK-8 is prepared by a facile nanocasting approach using cubic mesoporous silica KIT-6 as starting template. Afterwards, in order to increase the active sites of surface electrochemical reactions and promote the wettability in aqueous electrolyte, a chemical surface modification is carried out on the CMK-8 by nitric acid treatment. Two electrodes are prepared from the CMK-8 and the acid-modified CMK-8 (H-CMK-8) and used as the active materials for supercapacitors. The unique 3D mesoporous network combined with high specific surface area makes the nano-channel surfaces of the CMK-8 carbon favorable for charging the electric double-layer, resulting in that the CMK-8 and the H-CMK-8 electrodes both show well supercapacitive properties. Furthermore, the specific capacitance of the CMK-8 can be further improved by acid treatment, so that the H-CMK-8 exhibits the largest specific capacitance of 246 F g -1 at a current density of 0.625 A g -1 in 2 M KOH electrolyte. Also, the two carbon electrodes both exhibit good cycling stability and lifetime. Therefore, based on the above investigations, such CMK-8 carbon, especially H-CMK-8 carbon can be a potential candidate for supercapacitors.

New frontiers in materials science opened by ionic liquids.

PubMed

Torimoto, Tsukasa; Tsuda, Tetsuya; Okazaki, Ken-ichi; Kuwabata, Susumu

2010-03-19

Ionic liquids (ILs) including ambient-temperature molten salts, which exist in the liquid state even at room temperature, have a long research history. However, their applications were once limited because ILs were considered as highly moisture-sensitive solvents that should be handled in a glove box. After the first synthesis of moisture-stable ILs in 1992, their unique physicochemical properties became known in all scientific fields. ILs are composed solely of ions and exhibit several specific liquid-like properties, e.g., some ILs enable dissolution of insoluble bio-related materials and the use as tailor-made lubricants in industrial applications under extreme physicochemical conditions. Hybridization of ILs and other materials provides quasi-solid materials, which can be used to fabricate highly functional devices. ILs are also used as reaction media for electrochemical and chemical synthesis of nanomaterials. In addition, the negligible vapor pressure of ILs allows the fabrication of electrochemical devices that are operated under ambient conditions, and many liquid-vacuum technologies, such as X-ray photoelectron spectroscopy (XPS) analysis of liquids, electron microscopy of liquids, and sputtering and physical vapor deposition onto liquids. In this article, we review recent studies on ILs that are employed as functional advanced materials, advanced mediums for materials production, and components for preparing highly functional materials.

Synergistic gelation of silica nanoparticles and a sorbitol-based molecular gelator to yield highly-conductive free-standing gel electrolytes.

PubMed

Basrur, Veidhes R; Guo, Juchen; Wang, Chunsheng; Raghavan, Srinivasa R

2013-01-23

Lithium-ion batteries have emerged as the preferred type of rechargeable batteries, but there is a need to improve the performance of the electrolytes therein. Specifically, the challenge is to obtain electrolytes with the mechanical rigidity of solids but with liquid-like conductivities. In this study, we report a class of nanostructured gels that are able to offer this unique combination of properties. The gels are prepared by utilizing the synergistic interactions between a molecular gelator, 1,3:2,4-di-O-methyl-benzylidene-d-sorbitol (MDBS), and a nanoscale particulate material, fumed silica (FS). When MDBS and FS are combined in a liquid consisting of propylene carbonate with dissolved lithium perchlorate salt, the liquid electrolyte is converted into a free-standing gel due to the formation of a strong MDBS-FS network. The gels exhibit elastic shear moduli around 1000 kPa and yield stresses around 11 kPa-both values considerably exceed those obtainable by MDBS or FS alone in the same liquid. At the same time, the gel also exhibits electrochemical properties comparable to the parent liquid, including a high ionic conductivity (~5 × 10(-3) S/cm at room temperature) and a wide electrochemical stability window (up to 4.5 V).

Facile solvothermal synthesis of NaTi2(PO4)3/C porous plates as electrode materials for high-performance sodium ion batteries

NASA Astrophysics Data System (ADS)

Huang, Zhifeng; Liu, Li; Yi, Lingguang; Xiao, Wei; Li, Min; Zhou, Qian; Guo, Guoxiong; Chen, Xiaoying; Shu, Hongbo; Yang, Xiukang; Wang, Xianyou

2016-09-01

NaTi2(PO4)3/C porous plates have been successfully synthesized via solvothermal approach with ammonia as inductive agent combined in-situ carbon coating. It reveals that the inductive agent plays a critical role in morphology-controllable fabrication. The morphology, structure, and electrochemical properties of NaTi2(PO4)3/C composites with multilayered plates, single-layered plate, porous multilayered plates all have been investigated, which are prepared by using urea, triethylamine, and ammonia, respectively. Among these samples, NaTi2(PO4)3/C porous multilayered plates with ammonia addition exhibit the best electrochemical properties due to their unique mesoporous structure. NaTi2(PO4)3/C porous multilayered plates deliver an initial specific capacity of 125 and 110 mAh g-1 at 0.1 and 1 C, respectively. Furthermore, NaTi2(PO4)3/C porous multilayered plates show a good rate capability, whose capacity and corresponding capacity retention reach 85 mAh g-1 and 82.4%, respectively, after 120 cycles under the high rate of 10 C. The excellent results indicate that the NaTi2(PO4)3/C porous multilayered plates are a promising electrode candidate for sodium ion battery.

Detection of radiation-induced changes in electrochemical properties of austenitic stainless steels using miniaturized specimens and the single-loop electrochemical potentiokinetic reactivation method

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

Inazumi, T.; Bell, G.E.C.; Kenik, E.A.

1993-01-01

Single-loop electrochemical potentiokinetic reactivation testing of miniaturized (TEM) specimens can provide reliable data comparable to data obtained with larger specimens. Significant changes in electrochemical properties (increased reactivation current and Flade potential) were detected for PCA and type 316 stainless steels irradiated at 200--420[degrees]C up to 7--9 dpa. Irradiations in the FFTF Materials Open Test Assembly and in the Oak Ridge Research Reactor are reported on. 45 figs., 5 tabs., 52 refs.

Detection of radiation-induced changes in electrochemical properties of austenitic stainless steels using miniaturized specimens and the single-loop electrochemical potentiokinetic reactivation method

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

Inazumi, T.; Bell, G.E.C.; Kenik, E.A.

1993-01-01

Single-loop electrochemical potentiokinetic reactivation testing of miniaturized (TEM) specimens can provide reliable data comparable to data obtained with larger specimens. Significant changes in electrochemical properties (increased reactivation current and Flade potential) were detected for PCA and type 316 stainless steels irradiated at 200--420{degrees}C up to 7--9 dpa. Irradiations in the FFTF Materials Open Test Assembly and in the Oak Ridge Research Reactor are reported on. 45 figs., 5 tabs., 52 refs.

Preparation, electrochemical and spectral properties of free-base and manganese N-methyl-pyridylethynyl porphyrins.

PubMed

Lin, Ching-Yao; Chen, Yen-Chuan; Yao, Chi-Wen; Huang, Sung-Chou; Cheng, Yi-Hui

2008-02-14

Two series of free-base and manganese N-methyl-pyridylethynyl-5,15-biphenyl porphyrins were synthesized, and their UV-Visible, electrochemical and spectro-electrochemical properties were studied. Cyclic voltammetry experiments showed positive shifts in the reduction potentials and the UV-Visible spectra showed significant red-shifts in the absorption wavelengths of these porphyrins, indicating the effects of N-methyl-pyridylethynyl substituents.

Electrochemical Sensing and Imaging Based on Ion Transfer at Liquid/Liquid Interfaces

PubMed Central

Amemiya, Shigeru; Kim, Jiyeon; Izadyar, Anahita; Kabagambe, Benjamin; Shen, Mei; Ishimatsu, Ryoichi

2013-01-01

Here we review the recent applications of ion transfer (IT) at the interface between two immiscible electrolyte solutions (ITIES) for electrochemical sensing and imaging. In particular, we focus on the development and recent applications of the nanopipet-supported ITIES and double-polymer-modified electrode, which enable the dynamic electrochemical measurements of IT at nanoscopic and macroscopic ITIES, respectively. High-quality IT voltammograms are obtainable using either technique to quantitatively assess the kinetics and dynamic mechanism of IT at the ITIES. Nanopipet-supported ITIES serves as an amperometric tip for scanning electrochemical microscopy to allow for unprecedentedly high-resolution electrochemical imaging. Voltammetric ion sensing at double-polymer-modified electrodes offers high sensitivity and unique multiple-ion selectivity. The promising future applications of these dynamic approaches for bioanalysis and electrochemical imaging are also discussed. PMID:24363454

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.

Graphene and graphene-based materials for energy storage applications.

PubMed

Zhu, Jixin; Yang, Dan; Yin, Zongyou; Yan, Qingyu; Zhang, Hua

2014-09-10

With the increased demand in energy resources, great efforts have been devoted to developing advanced energy storage and conversion systems. Graphene and graphene-based materials have attracted great attention owing to their unique properties of high mechanical flexibility, large surface area, chemical stability, superior electric and thermal conductivities that render them great choices as alternative electrode materials for electrochemical energy storage systems. This Review summarizes the recent progress in graphene and graphene-based materials for four energy storage systems, i.e., lithium-ion batteries, supercapacitors, lithium-sulfur batteries and lithium-air batteries. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrospun carbon nanofibers surface-grafted with vapor-grown carbon nanotubes as hierarchical electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Zhou, Zhengping; Wu, Xiang-Fa; Fong, Hao

2012-01-01

This letter reports the fabrication and electrochemical properties of electrospun carbon nanofibers surface-grafted with vapor-grown carbon nanotubes (CNTs) as hierarchical electrodes for supercapacitors. The specific capacitance of the fabricated electrodes was measured up to 185 F/g at the low discharge current density of 625 mA/g; a decrease of 38% was detected at the high discharge current density of 2.5 A/g. The morphology and microstructure of the electrodes were examined by electron microscopy, and the unique connectivity of the hybrid nanomaterials was responsible for the high specific capacitance and low intrinsic contact electric resistance of the hierarchical electrodes.

Application of Ionic Liquids in Hydrometallurgy

PubMed Central

Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Lee, Jinyoung; Kwon, Kyungjung; Lee, Churl Kyoung

2014-01-01

Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry. PMID:25177864

Electrochemical and passive behaviour of tin alloyed ferritic stainless steel in concrete environment

NASA Astrophysics Data System (ADS)

Luo, Hong; Su, Huaizhi; Li, Baosong; Ying, Guobing

2018-05-01

In the present work, the electrochemical behavior and semiconducting properties of a tin alloyed ferritic stainless steel in simulated concrete solution in presence of NaCl were estimated by conventional electrochemical methods such as potentiodynamic polarization, electrochemical impedance spectroscopy, and capacitance measurement (Mott-Schottky approach). The surface passive film was analyzed by X-ray photoelectron spectroscopy. The results revealed a good agreement between pitting corrosion, electrochemical behaviour, and electronic properties. The p and n-type bilayer structure passive film were observed. The increase of Sn4+ oxide species in the passive film shows no beneficial effects on the pitting corrosion. In addition, the dehydration of the passive film was further discussed.

Electrochemical sensing platform based on the highly ordered mesoporous carbon-fullerene system.

PubMed

Zhou, Ming; Guo, Jidong; Guo, Li-ping; Bai, Jing

2008-06-15

In this paper, we report a novel all-carbon two-dimensionally ordered nanocomposite electrode system on the basis of the consideration of host-guest chemistry, which utilizes synergistic interactions between a nanostructured matrix of ordered mesoporous carbon (OMC) and an excellent electron acceptor of nanosized fullerene (C 60) to facilitate heterogeneous electron-transfer processes. The integration of OMC-C 60 by covalent interaction, especially its electrochemical applications for electrocatalysis, has not been explored thus far. Such integration may even appear to be counterintuitive because OMC and C 60 provide opposite electrochemical benefits in terms of facilitating heterogeneous electron-transfer processes. Nevertheless, the present work demonstrates the integration of OMC and C 60 can provide a remarkable synergistic augmentation of the current. To illuminate the concept, eight kinds of inorganic and organic electroactive compounds were employed to study the electrochemical response at an OMC-C 60 modified glassy carbon (OMC-C 60/GC) electrode for the first time, which shows more favorable electron-transfer kinetics than OMC/GC, carbon nanotube modified GC, C 60/GC, and GC electrodes. Such electrocatalytic behavior at OMC-C 60/GC electrode could be attributed to the unique physicochemical properties of OMC and C 60, especially the unusual host-guest synergy of OMC-C 60, which induced a substantial decrease in the overvoltage for NADH oxidation compared with GC electrode. The ability of OMC-C 60 to promote electron transfer not only suggests a new platform for the development of dehydrogenase-based bioelectrochemical devices but also indicates a potential of OMC-C 60 to be of a wide range of sensing applications because the electrocatalysis of different electroactive compounds at the OMC-C 60/GC electrode in this work should be a good model for constructing a novel and promising electrochemical sensing platform for further electrochemical detection of other biomolecules.

Best Practices for Operando Battery Experiments: Influences of X-ray Experiment Design on Observed Electrochemical Reactivity

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

Borkiewicz, O. J.; Wiaderek, Kamila M.; Chupas, Peter J.

Dynamic properties and multiscale complexities governing electrochemical energy storage in batteries are most ideally interrogated under simulated operating conditions within an electrochemical cell. We assess how electrochemical reactivity can be impacted by experiment design, including the X-ray measurements or by common features or adaptations of electrochemical cells that enable X-ray measurements.

Review of Fabrication Methods, Physical Properties, and Applications of Nanostructured Copper Oxides Formed via Electrochemical Oxidation.

PubMed

Stepniowski, Wojciech J; Misiolek, Wojciech Z

2018-05-29

Typically, anodic oxidation of metals results in the formation of hexagonally arranged nanoporous or nanotubular oxide, with a specific oxidation state of the transition metal. Recently, the majority of transition metals have been anodized; however, the formation of copper oxides by electrochemical oxidation is yet unexplored and offers numerous, unique properties and applications. Nanowires formed by copper electrochemical oxidation are crystalline and composed of cuprous (CuO) or cupric oxide (Cu₂O), bringing varied physical and chemical properties to the nanostructured morphology and different band gaps: 1.44 and 2.22 eV, respectively. According to its Pourbaix (potential-pH) diagram, the passivity of copper occurs at ambient and alkaline pH. In order to grow oxide nanostructures on copper, alkaline electrolytes like NaOH and KOH are used. To date, no systemic study has yet been reported on the influence of the operating conditions, such as the type of electrolyte, its temperature, and applied potential, on the morphology of the grown nanostructures. However, the numerous reports gathered in this paper will provide a certain view on the matter. After passivation, the formed nanostructures can be also post-treated. Post-treatments employ calcinations or chemical reactions, including the chemical reduction of the grown oxides. Nanostructures made of CuO or Cu₂O have a broad range of potential applications. On one hand, with the use of surface morphology, the wetting contact angle is tuned. On the other hand, the chemical composition (pure Cu₂O) and high surface area make such materials attractive for renewable energy harvesting, including water splitting. While compared to other fabrication techniques, self-organized anodization is a facile, easy to scale-up, time-efficient approach, providing high-aspect ratio one-dimensional (1D) nanostructures. Despite these advantages, there are still numerous challenges that have to be faced, including the strict control of the chemical composition and morphology of the grown nanostructures, their uniformity, and understanding the mechanism of their growth.

Redox Active Polymers as Soluble Nanomaterials for Energy Storage.

PubMed

Burgess, Mark; Moore, Jeffrey S; Rodríguez-López, Joaquín

2016-11-15

It is an exciting time for exploring the synergism between the chemical and dimensional properties of redox nanomaterials for addressing the manifold performance demands faced by energy storage technologies. The call for widespread adoption of alternative energy sources requires the combination of emerging chemical concepts with redesigned battery formats. Our groups are interested in the development and implementation of a new strategy for nonaqueous flow batteries (NRFBs) for grid energy storage. Our motivation is to solve major challenges in NRFBs, such as the lack of membranes that simultaneously allow fast ion transport while minimizing redox active species crossover between anolyte (negative electrolyte) and catholyte (positive electrolyte) compartments. This pervasive crossover leads to deleterious capacity fade and materials underutilization. In this Account, we highlight redox active polymers (RAPs) and related polymer colloids as soluble nanoscopic energy storing units that enable the simple but powerful size-exclusion concept for NRFBs. Crossover of the redox component is suppressed by matching high molecular weight RAPs with simple and inexpensive nanoporous commercial separators. In contrast to the vast literature on the redox chemistry of electrode-confined polymer films, studies on the electrochemistry of solubilized RAPs are incipient. This is due in part to challenges in finding suitable solvents that enable systematic studies on high polymers. Here, viologen-, ferrocene- and nitrostyrene-based polymers in various formats exhibit properties that make amenable their electrochemical exploration as solution-phase redox couples. A main finding is that RAP solutions store energy efficiently and reversibly while offering chemical modularity and size versatility. Beyond the practicality toward their use in NRFBs, the fundamental electrochemistry exhibited by RAPs is fascinating, showing clear distinctions in behavior from that of small molecules. Whereas RAPs conveniently translate the redox properties of small molecules into a nanostructure, they give rise to charge transfer mechanisms and electrolyte interactions that elicit distinct electrochemical responses. To understand how the electrochemical characteristics of RAPs depend on molecular features, including redox moiety, macromolecular size, and backbone structure, a range of techniques has been employed by our groups, including voltammetry at macro- and microelectrodes, rotating disk electrode voltammetry, bulk electrolysis, and scanning electrochemical microscopy. RAPs rely on three-dimensional charge transfer within their inner bulk, which is an efficient process and allows quantitative electrolysis of particles of up to ∼800 nm in radius. Interestingly, we find that interactions between neighboring pendants create unique opportunities for fine-tuning their electrochemical reactivity. Furthermore, RAP interrogation toward the single particle limit promises to shed light on fundamental charge storage mechanisms.

All-solid-state flexible supercapacitors fabricated with bacterial nanocellulose papers, carbon nanotubes, and triblock-copolymer ion gels.

PubMed

Kang, Yu Jin; Chun, Sang-Jin; Lee, Sung-Suk; Kim, Bo-Yeong; Kim, Jung Hyeun; Chung, Haegeun; Lee, Sun-Young; Kim, Woong

2012-07-24

We demonstrate all-solid-state flexible supercapacitors with high physical flexibility, desirable electrochemical properties, and excellent mechanical integrity, which were realized by rationally exploiting unique properties of bacterial nanocellulose, carbon nanotubes, and ionic liquid based polymer gel electrolytes. This deliberate choice and design of main components led to excellent supercapacitor performance such as high tolerance against bending cycles and high capacitance retention over charge/discharge cycles. More specifically, the performance of our supercapacitors was highly retained through 200 bending cycles to a radius of 3 mm. In addition, the supercapacitors showed excellent cyclability with C(sp) (~20 mF/cm(2)) reduction of only <0.5% over 5000 charge/discharge cycles at the current density of 10 A/g. Our demonstration could be an important basis for material design and development of flexible supercapacitors.

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.

Electrochemical properties of copper-based compounds with polyanion frameworks

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

Mizuno, Yoshifumi; Hata, Shoma; Suzuki, Kota

The copper-based polyanion compounds Li{sub 6}CuB{sub 4}O{sub 10} and Li{sub 2}CuP{sub 2}O{sub 7} were synthesized using a conventional solid-state reaction, and their electrochemical properties were determined. Li{sub 6}CuB{sub 4}O{sub 10} showed reversible capacity of 340 mA g{sup −1} at the first discharge–charge process, while Li{sub 2}CuP{sub 2}O{sub 7} showed large irreversible capacity and thus low charge capacity. Ex situ X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) measurements revealed that the electrochemical Li{sup +} intercalation/deintercalation reaction in Li{sub 6}CuB{sub 4}O{sub 10} occurred via reversible Cu{sup 2+}/Cu{sup +} reduction/oxidation reaction. These differences in their discharge/charge mechanisms are discussed basedmore » on the strength of the Cu–O covalency via their inductive effects. - Graphical abstract: Electrochemical properties for Cu-based polyanion compounds were investigated. The electrochemical reaction mechanisms are strongly affected by their Cu–O covalentcy. - Highlights: • Electrochemical properties of Cu-based polyanion compounds were investigated. • The Li{sup +} intercalation/deintercalation reaction progressed in Li{sub 6}CuB{sub 4}O{sub 10}. • The electrochemical displacement reaction progressed in Li{sub 2}CuP{sub 2}O{sub 7}. • The strength of Cu–O covalency affects the reaction mechanism.« less

Nickel hydroxide nanoparticles-reduced graphene oxide nanosheets film: layer-by-layer electrochemical preparation, characterization and rifampicin sensory application.

PubMed

Rastgar, Shokoufeh; Shahrokhian, Saeed

2014-02-01

Electrochemical deposition, as a well-controlled synthesis procedure, has been used for subsequently layer-by-layer preparation of nickel hydroxide nanoparticle-reduced graphene oxide nanosheets (Ni(OH)2-RGO) on a graphene oxide (GO) film pre-cast on a glassy carbon electrode surface. The surface morphology and nature of the nano-hybrid film (Ni(OH)2-RGO) was thoroughly characterized by scanning electron and atomic force microscopy, spectroscopy and electrochemical techniques. The modified electrode appeared as an effective electro-catalytic model for analysis of rifampicin (RIF) by using linear sweep voltammetry (LSV). The prepared modified electrode exhibited a distinctly higher activity for electro-oxidation of RIF than either GO, RGO nanosheets or Ni(OH)2 nanoparticles. Enhancement of peak currents is ascribed to the fast heterogeneous electron transfer kinetics that arise from the synergistic coupling between the excellent properties of RGO nanosheets (such as high density of edge plane sites, subtle electronic characteristics and attractive π-π interaction) and unique properties of metal nanoparticles. Under the optimized analysis conditions, the modified electrode showed two oxidation processes for rifampicin at potentials about 0.08 V (peak I) and 0.69 V (peak II) in buffer solution of pH 7.0 with a wide linear dynamic range of 0.006-10.0 µmol L(-1) and 0.04-10 µmol L(-1) with a detection limit of 4.16 nmol L(-1) and 2.34 nmol L(-1) considering peaks I and II as an analytical signal, respectively. The results proved the efficacy of the fabricated modified electrode for simple, low cost and highly sensitive medicine sensor well suited for the accurate determinations of trace amounts of rifampicin in the pharmaceutical and clinical preparations. © 2013 Elsevier B.V. All rights reserved.

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.

High Power Electrochemical Capacitors

DTIC Science & Technology

2012-03-23

electrochemical properties of vanadium oxide aerogels prepared by a freeze-drying process. Journal of the Electrochemical Society, 2004. 151(5): p...Electrochemical Society, 2002. 149(1): p. A26-A30. 12. Rolison, D.R. and B. Dunn, Electrically conductive oxide aerogels : new materials in...surface area vanadium oxide aerogels . Electrochemical and Solid-State Letters, 2000. 3(10): p. 457-459. 14. Shembel, E., et al., Synthesis, investigation

Electrochemical deposited nickel nanowires: influence of deposition bath temperature on the morphology and physical properties

NASA Astrophysics Data System (ADS)

Sofiah, A. G. N.; Kananathan, J.; Samykano, M.; Ulakanathan, S.; Lah, N. A. C.; Harun, W. S. W.; Sudhakar, K.; Kadirgama, K.; Ngui, W. K.; Siregar, J. P.

2017-10-01

This paper investigates the influence of the electrolytic bath temperature on the morphology and physical properties of nickel (Ni) nanowires electrochemically deposited into the anodic alumina oxide porous membrane (AAO). The synthesis was performed using nickel sulfate hexahydrate (NiSO4.6H2O) and boric acid (H3BO3) as an electrolytic bath for the electrochemical deposition of Ni nanowires. During the experiment, the electrolyte bath temperature varied from 40°C, 80°C, and 120°C. After the electrochemical deposition process, AAO templates cleaned with distilled water preceding to dissolution in sodium hydroxide (NaOH) solution to obtain free-standing Ni nanowires. Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDX) and X-ray Diffraction (XRD) analysis were employed to characterize the morphology and physical properties of the synthesized Ni nanowires. Finding reveals the electrodeposition bath temperature significantly influences the morphology and physical properties of the synthesized Ni nanowires. Rougher surface texture, larger crystal size, and longer Ni nanowires obtained as the deposition bath temperature increased. From the physical properties properties analysis, it can be concluded that deposition bath temperature influence the physical properties of Ni nanowires.

Viscosity, conductivity, and electrochemical property of dicyanamide ionic liquids

NASA Astrophysics Data System (ADS)

Yuan, Wen-Li; Yang, Xiao; He, Ling; Xue, Ying; Qin, Song; Tao, Guo-Hong

2018-03-01

The instructive structure-property relationships of ionic liquids (ILs) can be put to task-specific design of new functionalized ILs. The dicyanamide (DCA) ILs are typical CHN type ILs which are halogen free, chemical stable, low-viscous and fuel-rich. The transport properties of DCA ionic liquids are significant for their applications as solvents, electrolytes and hypergolic propellants. This work systematically investigates several important transport properties of four DCA ILs ([C4mim][N(CN)2], [C4m2im][N(CN)2], N4442[N(CN)2], and N8444[N(CN)2]) including viscosity, conductivity, and electrochemical property at different temperatures. The melting points, temperature-dependent viscosities and conductivities reveal the structure-activity relationship of four DCA ILs. From the Walden plots, the imidazolium cations exhibit stronger cation–anion attraction than the ammonium cations. DCA ILs have relatively high values of electrochemical windows (EWs), which indicates that the DCA ILs are potential candidates for electrolytes in electrochemical applications. The cyclic voltammograms of Eu(III) in these DCA ILs at GC working electrode at various temperatures 303–333 K consists of quasi-reversible waves. The electrochemical properties of the DCA ILs are also dominated by the cationic structures. The current intensity (ip), the diffusion coefficients (Do), the charge transfer rate constants (ks) of Eu(III) in DCA ILs all increased with the molar conductivities increased. The cationic structure-transport property relationships of DCA ILs were constructed for designing novel functionalized ILs to fulfill specific demands.

Viscosity, Conductivity, and Electrochemical Property of Dicyanamide Ionic Liquids

PubMed Central

Yuan, Wen-Li; Yang, Xiao; He, Ling; Xue, Ying; Qin, Song; Tao, Guo-Hong

2018-01-01

The instructive structure-property relationships of ionic liquids (ILs) can be put to task-specific design of new functionalized ILs. The dicyanamide (DCA) ILs are typical CHN type ILs which are halogen free, chemical stable, low-viscous, and fuel-rich. The transport properties of DCA ionic liquids are significant for their applications as solvents, electrolytes, and hypergolic propellants. This work systematically investigates several important transport properties of four DCA ILs ([C4mim][N(CN)2], [C4m2im][N(CN)2], N4442[N(CN)2], and N8444[N(CN)2]) including viscosity, conductivity, and electrochemical property at different temperatures. The melting points, temperature-dependent viscosities and conductivities reveal the structure-activity relationship of four DCA ILs. From the Walden plots, the imidazolium cations exhibit stronger cation–anion attraction than the ammonium cations. DCA ILs have relatively high values of electrochemical windows (EWs), which indicates that the DCA ILs are potential candidates for electrolytes in electrochemical applications. The cyclic voltammograms of Eu(III) in these DCA ILs at GC working electrode at various temperatures 303–333 K consists of quasi-reversible waves. The electrochemical properties of the DCA ILs are also dominated by the cationic structures. The current intensity (ip), the diffusion coefficients (Do), the charge transfer rate constants (ks) of Eu(III) in DCA ILs all increased with the molar conductivities increased. The cationic structure-transport property relationships of DCA ILs were constructed for designing novel functionalized ILs to fulfill specific demands. PMID:29600245

Contribution of tin in electrochemical properties of zinc antimonate nanostructures: An electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Balasubramaniam, M.; Balakumar, S.

2018-04-01

Tin (Sn) doped ZnSb2O6 nanostructures was synthesized by chemical precipitation method and was used as an electrode material for supercapacitors to explore its electrochemical stability and potentiality as energy storage materials. Their characteristic structural, morphological and compositional features were investigated through XRD, FESEM and XPS analysis. Results showed that the nanostructures have well ordered crystalline features with spherical particle morphology. As the size and morphology are the vital parameters in exhibiting better electrochemical properties, the prepared nanostructures exhibited a significant specific capacitance of 222 F/g at a current density of 0.5 A/g respectively. While charging and discharging for 1000 cycles, the capacitance retention was enhanced to 105.0% which depicts the stability and activeness of electrochemical sites present in the Sn doped ZnSb2O6 nanostructures even after cycling. Hence, the inclusion of Sn into ZnSb2O6 has contributed in improving the electrochemical properties thereby it represents itself as a potential electrode material for supercapacitors.

BF 3-promoted electrochemical properties of quinoxaline in propylene carbonate

DOE PAGES

Carino, Emily V.; Diesendruck, Charles E.; Moore, Jeffrey S.; ...

2015-02-04

Electrochemical and density functional studies demonstrate that coordination of electrolyte constituents to quinoxalines modulates their electrochemical properties. Quinoxalines are shown to be electrochemically inactive in most electrolytes in propylene carbonate, yet the predicted reduction potential is shown to match computational estimates in acetonitrile. We find that in the presence of LiBF 4 and trace water, an adduct is formed between quinoxaline and the Lewis acid BF3, which then displays electrochemical activity at 1–1.5 V higher than prior observations of quinoxaline electrochemistry in non-aqueous media. Direct synthesis and testing of a bis-BF 3 quinoxaline complex further validates the assignment of themore » electrochemically active species, presenting up to a ~26-fold improvement in charging capacity, demonstrating the advantages of this adduct over unmodified quinoxaline in LiBF 4-based electrolyte. The use of Lewis acids to effectively “turn on” the electrochemical activity of organic molecules may lead to the development of new active material classes for energy storage applications.« less

Alcohol dehydrogenase of acetic acid bacteria: structure, mode of action, and applications in biotechnology.

PubMed

Yakushi, Toshiharu; Matsushita, Kazunobu

2010-05-01

Pyrroquinoline quinone-dependent alcohol dehydrogenase (PQQ-ADH) of acetic acid bacteria is a membrane-bound enzyme involved in the acetic acid fermentation by oxidizing ethanol to acetaldehyde coupling with reduction of membranous ubiquinone (Q), which is, in turn, re-oxidized by ubiquinol oxidase, reducing oxygen to water. PQQ-ADHs seem to have co-evolved with the organisms fitting to their own habitats. The enzyme consists of three subunits and has a pyrroloquinoline quinone, 4 heme c moieties, and a tightly bound Q as the electron transfer mediators. Biochemical, genetic, and electrochemical studies have revealed the unique properties of PQQ-ADH since it was purified in 1978. The enzyme is unique to have ubiquinol oxidation activity in addition to Q reduction. This mini-review focuses on the molecular properties of PQQ-ADH, such as the roles of the subunits and the cofactors, particularly in intramolecular electron transport of the enzyme from ethanol to Q. Also, we summarize biotechnological applications of PQQ-ADH as to enantiospecific oxidations for production of the valuable chemicals and bioelectrocatalysis for sensors and fuel cells using indirect and direct electron transfer technologies and discuss unsolved issues and future prospects related to this elaborate enzyme.

Highly uniform Co9S8 nanoparticles grown on graphene nanosheets as advanced anode materials for improved Li-storage performance

NASA Astrophysics Data System (ADS)

Liu, Shumin; Wang, Jinxian; Wang, Jianwei; Zhang, Feifei; Wang, Limin

2016-12-01

A Co9S8/GNS (graphene nanosheets) nanocomposites has been synthesized via a facile solvothermal approach followed by thermal treatment in nitrogen at 500 °C using graphite oxide sheets, CoCl2·6H2O and thiourea as the starting materials. Highly uniform Co9S8 nanoparticles with a size of about 80-90 nm are evenly grafted on the surface of GNS, forming a unique Co9S8/GNS hybrid nanostructure. When evaluated as anode materials for lithium ion batteries, impressive electrochemical performances of the as-prepared nanocomposites are achieved compared to that of pure bulk Co9S8, with an high reversible capacity of 1480 mAh g-1. Moreover, the as-synthesized nanocomposites present excellent cycling durability and high-rate capability. The improvement in the electrochemical properties could be attributed to the well-designed structure of the Co9S8/GNS nanocomposite which possesses large number of accessible active sites for lithium-ion insertion, fast ion diffusion rate and good electronic conductivity.

Controlling the shape of LiCoPO4 nanocrystals by supercritical fluid process for enhanced energy storage properties

PubMed Central

Truong, Quang Duc; Devaraju, Murukanahally Kempaiah; Ganbe, Yoshiyuki; Tomai, Takaaki; Honma, Itaru

2014-01-01

Lithium-ion batteries offer promising opportunities for novel energy storage systems and future application in hybrid electric vehicles or electric vehicles. Cathode materials with high energy density are required for practical application. Herein, high-voltage LiCoPO4 cathode materials with different shapes and well-developed facets such as nanorods and nanoplates with exposed {010} facets have been synthesized by a one-pot supercritical fluid (SCF) processing. The effect of different amines and their roles on the morphology-control has been investigated in detail. It was found that amine having long alkyl chain such as hexamethylenediamine played important roles to manipulate the shape of the nanocrystals by selective adsorption on the specific {010} facets. More importantly, the nanorods and nanoplates showed better electrochemical performance than that of nanoparticles which was attributed to their unique crystallographic orientation with short Li ion diffusion path. The present study emphasizes the importance of crystallographic orientation in improving the electrochemical performance of the high voltage LiCoPO4 cathode materials for Li-ion batteries. PMID:24496051

Biomimetic Graphene-Based 3D Scaffold for Long-Term Cell Culture and Real-Time Electrochemical Monitoring.

PubMed

Hu, Xue-Bo; Liu, Yan-Ling; Wang, Wen-Jie; Zhang, Hai-Wei; Qin, Yu; Guo, Shan; Zhang, Xin-Wei; Fu, Lei; Huang, Wei-Hua

2018-01-16

Current achievements on electrochemical monitoring of cells are often gained on two-dimensional (2D) substrates, which fail in mimicking the cellular environments and accurately reproducing the cellular functions within a three-dimensional (3D) tissue. In this regard, 3D scaffold concurrently integrated with the function of cell culture and electrochemical sensing is conceivably a promising platform to monitor cells in real time under their in vivo-like 3D microenvironments. However, it is particularly challenging to construct such a multifunctional scaffold platform. Herein, we developed a 3-aminophenylboronic acid (APBA) functionalized graphene foam (GF) network, which combines the biomimetic property of APBA with the mechanical and electrochemical properties of GF. Hence, the GF network can serve as a 3D scaffold to culture cells for a long period with high viability and simultaneously as an electrode for highly sensitive electrochemical sensing. This allows monitoring of gaseous messengers H 2 S released from the cells cultured on the 3D scaffold in real time. This work represents considerable progress in fabricating 3D cell culture scaffold with electrochemical properties, thereby facilitating future studies of physiologically relevant processes.

Effect of Zr, Nb and Ti addition on injection molded 316L stainless steel for bio-applications: Mechanical, electrochemical and biocompatibility properties.

PubMed

Gulsoy, H Ozkan; Pazarlioglu, Serdar; Gulsoy, Nagihan; Gundede, Busra; Mutlu, Ozal

2015-11-01

The research investigated the effect of Zr, Nb and Ti additions on mechanical, electrochemical properties and biocompatibility of injection molded 316L stainless steel. Addition of elemental powder is promoted to get high performance of sintered 316L stainless steels. The amount of additive powder plays a role in determining the sintered microstructure and all properties. In this study, 316L stainless steel powders used with the elemental Zr, Nb and Ti powders. A feedstock containing 62.5 wt% powders loading was molded at different injection molded temperature. The binders were completely removed from molded components by solvent and thermal debinding at different temperatures. The debinded samples were sintered at 1350°C for 60 min. Mechanical, electrochemical property and biocompatibility of the sintered samples were performed mechanical, electrochemical, SBF immersion tests and cell culture experiments. Results of study showed that sintered 316L and 316L with additives samples exhibited high corrosion properties and biocompatibility in a physiological environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

The Influence of Nanopore Dimensions on the Electrochemical Properties of Nanopore Arrays Studied by Impedance Spectroscopy

PubMed Central

Kant, Krishna; Priest, Craig; Shapter, Joe G.; Losic, Dusan

2014-01-01

The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 μm to 20 μm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores. PMID:25393785

Advanced Micro/Nanostructures for Lithium Metal Anodes

PubMed Central

Zhang, Rui; Li, Nian‐Wu; Cheng, Xin‐Bing; Yin, Ya‐Xia

2017-01-01

Owning to their very high theoretical capacity, lithium metal anodes are expected to fuel the extensive practical applications in portable electronics and electric vehicles. However, unstable solid electrolyte interphase and lithium dendrite growth during lithium plating/stripping induce poor safety, low Coulombic efficiency, and short span life of lithium metal batteries. Lately, varies of micro/nanostructured lithium metal anodes are proposed to address these issues in lithium metal batteries. With the unique surface, pore, and connecting structures of different nanomaterials, lithium plating/stripping processes have been regulated. Thus the electrochemical properties and lithium morphologies have been significantly improved. These micro/nanostructured lithium metal anodes shed new light on the future applications for lithium metal batteries. PMID:28331792

Controlled fabrication of PANI/CNF hybrid films: molecular interaction induced various micromorphologies and electrochemical properties.

PubMed

Xu, Guiheng; Xu, Dongdong; Zhang, Jianan; Wang, Kaixi; Chen, Zhimin; Chen, Jiafu; Xu, Qun

2013-12-01

In this paper, a facile and efficient method is reported to prepare polyaniline/carbon nanofiber (PANI/CNF) hybrid films by in situ chemical polymerization of aniline. The various morphologies and microstructures of PANI/CNF hybrid films can be controlled by adjusting the concentration of aniline and different acids as the protonation reagent, and the formation mechanism is illustrated in this study. The surface morphologies and chemical structure of the PANI/CNF hybrid films are characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), water contact angle (CA), FT-IR, Raman, and UV-vis spectrophotometers. The different morphology of uniformly coated, twist-tangled, and needle-like PANI built on CNF films are obtained by using HCl, H2SO4, and HClO4 as protonation reagent and the obtained hybrid films are labeled as PANI/CNF-f1, PANI/CNF-f2, and PANI/CNF-f3, respectively. We demonstrated that the different protonation reagent has the determined effect on the surface properties of the obtained hybrid films that can transfer from hydrophilic to hydrophobic. Besides, the various morphologies of PANI play an important role in their electrochemical properties. PANI/CNF-f3 exhibits higher specific capacitance and better stability than that of the PANI/CNF-f1 and PANI/CNF-f2. Considering its unique needle-like structure, this work is a proof of concept that micro-structure and morphology can determine the macro-properties. And this study supplies a facile method to fabricate PANI/CNF hybrid films that can be used as electrode materials in supercapacitors. Copyright © 2013 Elsevier Inc. All rights reserved.

Investigation on the electrochemical interfacial properties of 2-aminothiophenol functionalized graphene oxide modified electrode

NASA Astrophysics Data System (ADS)

Immanuel, Susan; Aparna T., K.; Sivasubramanian, R.

2018-04-01

In this paper the interfacial behavior of graphene oxide and 2-aminothiophenol functionalized graphene oxide was investigated by electrochemical method. The GO was prepared by modified Hummers method and the 2-aminothiophenol was covalently attached on the surface of GO sheets. The electrochemical properties were investigated using a redox couple and the electrokinetic parameter was inferred. It was found that the ATP-GO exhibited slow kinetics compared to GO due to the increased deformation of GO sheets after ATP functionalization.

One-step electrodeposition of graphene loaded nickel oxides nanoparticles for acetaminophen detection.

PubMed

Liu, Gui-Ting; Chen, Hui-Fen; Lin, Guo-Ming; Ye, Ping-ping; Wang, Xiao-Ping; Jiao, Ying-Zhi; Guo, Xiao-Yu; Wen, Ying; Yang, Hai-Feng

2014-06-15

An electrochemical sensor of acetaminophen (AP) based on electrochemically reduced graphene (ERG) loaded nickel oxides (Ni2O3-NiO) nanoparticles coated onto glassy carbon electrode (ERG/Ni2O3-NiO/GCE) was prepared by a one-step electrodeposition process. The as-prepared electrode was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The electrocatalytic properties of ERG/Ni2O3-NiO modified glassy carbon electrode toward the oxidation of acetaminophen were analyzed via cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The electrodes of Ni2O3-NiO/GCE, ERG/GCE, and Ni2O3-NiO deposited ERG/GCE were fabricated for the comparison and the catalytic mechanism understanding. The studies showed that the one-step prepared ERG/Ni2O3-NiO/GCE displayed the highest electro-catalytic activity, attributing to the synergetic effect derived from the unique composite structure and physical properties of nickel oxides nanoparticles and graphene. The low detection limit of 0.02 μM (S/N=3) with the wide linear detection range from 0.04 μM to 100 μM (R=0.998) was obtained. The resulting sensor was successfully used to detect acetaminophen in commercial pharmaceutical tablets and urine samples. Copyright © 2014 Elsevier B.V. All rights reserved.

The orientation construction of S and N dual-doped discoid-like graphene with high-rate electrode property

NASA Astrophysics Data System (ADS)

Song, Xinyu; Ma, Xinlong; Ning, Guoqing; Gao, Daowei; Yu, Zhiqing; Xiao, Zhihua

2018-06-01

The orientation construction of S and N dual-doped discoid-like graphene (labeled as SNDG) is achieved by regular arrangement of the polycyclic aromatics in pitch molecules using natural diatomites as templates. The superior electrochemical energy storage ability of SNDG is demonstrated by cathode and anode tests, respectively. The synergistic effects of the robust scaffold coupled with the hollow structure, unique porous structure, the excellent structural stability and the dual-doping of S and N lead to the electrode property enhancement in terms of rate capability and durability. The Li ion hybrid capacitor using SNDG as both anode and cathode, presents excellent long-term cycling stability and markedly energy and power densities (up to 143 Wh kg-1 and 13,548 W kg-1). This work provides a novel pathway to realize the mass production of high-rate electrode materials via the high value-added utilization of pitch.

Ionic liquids and their solid-state analogues as materials for energy generation and storage

NASA Astrophysics Data System (ADS)

Macfarlane, Douglas R.; Forsyth, Maria; Howlett, Patrick C.; Kar, Mega; Passerini, Stefano; Pringle, Jennifer M.; Ohno, Hiroyuki; Watanabe, Masayoshi; Yan, Feng; Zheng, Wenjun; Zhang, Shiguo; Zhang, Jie

2016-02-01

Salts that are liquid at room temperature, now commonly called ionic liquids, have been known for more than 100 years; however, their unique properties have only come to light in the past two decades. In this Review, we examine recent work in which the properties of ionic liquids have enabled important advances to be made in sustainable energy generation and storage. We discuss the use of ionic liquids as media for synthesis of electromaterials, for example, in the preparation of doped carbons, conducting polymers and intercalation electrode materials. Focusing on their intrinsic ionic conductivity, we examine recent reports of ionic liquids used as electrolytes in emerging high-energy-density and low-cost batteries, including Li-ion, Li-O2, Li-S, Na-ion and Al-ion batteries. Similar developments in electrolyte applications in dye-sensitized solar cells, thermo-electrochemical cells, double-layer capacitors and CO2 reduction are also discussed.

Toward highly efficient electrocatalyst for Li–O 2 batteries using biphasic N-doping cobalt@graphene multiple-capsule heterostructures

DOE PAGES

Tan, Guoqiang; Chong, Lina; Amine, Rachid; ...

2017-04-12

To promote lithium-oxygen batteries available for practical applications, the development of advanced cathode catalysts with low-cost, high activity and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport, and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@graphene multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium-oxygen cells. The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electro-active zones possible; furthermore, the colander-like porous electrode facilitates themore » oxygen diffusion, catalytic reaction, and stable deposition of discharge products. Finally, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.« less

Toward Highly Efficient Electrocatalyst for Li–O 2 Batteries Using Biphasic N-Doping Cobalt@Graphene Multiple-Capsule Heterostructures

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

Tan, Guoqiang; Chong, Lina; Amine, Rachid

For the promotion of lithium oxygen batteries available for :practical applications, the development of advanced cathode catalysts with low-high activity, and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@grapbene Multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium oxygen cells. 'The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electroactive zones possible; furthermore the colander-like porousmore » electrode facilitates the oxygen diffusion, catalytic reaction,and stable deposition of discharge products. As a result, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.« less

Toward highly efficient electrocatalyst for Li–O 2 batteries using biphasic N-doping cobalt@graphene multiple-capsule heterostructures

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

Tan, Guoqiang; Chong, Lina; Amine, Rachid

To promote lithium-oxygen batteries available for practical applications, the development of advanced cathode catalysts with low-cost, high activity and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport, and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@graphene multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium-oxygen cells. The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electro-active zones possible; furthermore, the colander-like porous electrode facilitates themore » oxygen diffusion, catalytic reaction, and stable deposition of discharge products. Finally, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.« less

Toward Highly Efficient Electrocatalyst for Li-O2 Batteries Using Biphasic N-Doping Cobalt@Graphene Multiple-Capsule Heterostructures.

PubMed

Tan, Guoqiang; Chong, Lina; Amine, Rachid; Lu, Jun; Liu, Cong; Yuan, Yifei; Wen, Jianguo; He, Kun; Bi, Xuanxuan; Guo, Yuanyuan; Wang, Hsien-Hau; Shahbazian-Yassar, Reza; Al Hallaj, Said; Miller, Dean J; Liu, Dijia; Amine, Khalil

2017-05-10

For the promotion of lithium-oxygen batteries available for practical applications, the development of advanced cathode catalysts with low-cost, high activity, and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@graphene multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium-oxygen cells. The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electroactive zones possible; furthermore, the colander-like porous electrode facilitates the oxygen diffusion, catalytic reaction, and stable deposition of discharge products. As a result, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.

Biodegradable/biocompatible coated metal implants for orthopedic applications.

PubMed

Saleh, Mohamed M; Touny, A H; Al-Omair, Mohammed A; Saleh, M M

2016-05-12

Biocompatible metals have been suggested as revolutionary biomaterials for bone-grafting therapies. Although metals and their alloys are widely and successfully used in producing biomedical implants due to their good mechanical properties and corrosion resistance, they have a lack in bioactivity. Therefore coating of the metal surface with calcium phosphates (CaP) is a benign way to achieve well bioactivity and get controlled corrosion properties. The biocompatibility and bioactivity calcium phosphates (CaP) in bone growth were guided them to biomedical treatment of bone defects and fractures. Many techniques have been used for fabrication of CaP coatings on metal substrates such as magnesium and titanium. The present review will focus on the synthesis of CaP and their relative forms using different techniques especially electrochemical techniques. The latter has always been known of its unique way of optimizing the process parameters that led to a control in the structure and characteristics of the produced materials.

Lithium salts for advanced lithium batteries: Li-metal, Li-O 2, and Li-S

DOE PAGES

Younesi, Reza; Veith, Gabriel M.; Johansson, Patrik; ...

2015-06-01

Presently lithium hexafluorophosphate (LiPF 6) is the dominant Li-salt used in commercial rechargeable lithium-ion batteries (LIBs) based on a graphite anode and a 3-4 V cathode material. While LiPF 6 is not the ideal Li-salt for every important electrolyte property, it has a uniquely suitable combination of properties (temperature range, passivation, conductivity, etc.) rendering it the overall best Li-salt for LIBs. However, this may not necessarily be true for other types of Li-based batteries. Indeed, next generation batteries, for example lithium-metal (Li-metal), lithium-oxygen (Li-O 2), and lithium sulphur (Li-S), require a re-evaluation of Li-salts due to the different electrochemical andmore » chemical reactions and conditions within such cells. Furthermore, this review explores the critical role Li-salts play in ensuring in these batteries viability.« less

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.

Development of ionic gels using thiol-based monomers in ionic liquid

NASA Astrophysics Data System (ADS)

Ahmed, Kumkum; Naga, Naofumi; Kawakami, Masaru; Furukawa, Hidemitsu

2016-04-01

Ionic gels (IGs) using ionic liquids (ILs) can propose diverse applications in the field of optics, sensors and separation have opened wide prospects in materials science. ILs have attracted remarkable interest for gel polymer electrolytes and batteries based on their useful properties such as non-volatility, non-flammability, a wide electrochemical window, high thermal stability and a high ionic conductivity. The formation of gel in IL media makes it possible to immobilize ILs within organic or inorganic matrices and to take advantage of their unique properties in the solid state, thus eliminating some shortcomings related to shaping and risk of leakage. In this work for the first time we used multifunctional thiol monomers having uniform structure and good compatibility with the IL of our interest. Therefore we focused on developing thiol monomer-based IGs using multifunctional thiol monomers and acrylate crosslinkers utilizing thiol-ene reaction between monomer and crosslinking molecules in an IL medium and characterize their physico-chemical properties like thermal, conductive, mechanical properties etc.. This work has been focused mainly to improve the mechanical strength of IGs and make prospects of IGs in tribology and lubricants.

Novel technique for online characterization of cartilaginous tissue properties.

PubMed

Yuan, Tai-Yi; Huang, Chun-Yuh; Yong Gu, Wei

2011-09-01

The goal of tissue engineering is to use substitutes to repair and restore organ function. Bioreactors are an indispensable tool for monitoring and controlling the unique environment for engineered constructs to grow. However, in order to determine the biochemical properties of engineered constructs, samples need to be destroyed. In this study, we developed a novel technique to nondestructively online-characterize the water content and fixed charge density of cartilaginous tissues. A new technique was developed to determine the tissue mechano-electrochemical properties nondestructively. Bovine knee articular cartilage and lumbar annulus fibrosus were used in this study to demonstrate that this technique could be used on different types of tissue. The results show that our newly developed method is capable of precisely predicting the water volume fraction (less than 3% disparity) and fixed charge density (less than 16.7% disparity) within cartilaginous tissues. This novel technique will help to design a new generation of bioreactors which are able to actively determine the essential properties of the engineered constructs, as well as regulate the local environment to achieve the optimal conditions for cultivating constructs.

Prospects for graphene–nanoparticle-based hybrid sensors

PubMed Central

Yin, Perry T.; Kim, Tae-Hyung; Choi, Jeong-Woo; Lee, Ki-Bum

2014-01-01

Graphene is a single-atom thick, two-dimensional sheet of carbon that is characterized by exceptional chemical, electrical, material, optical, and physical properties. As a result, graphene and related materials, such as graphene oxide and reduced graphene oxide, have been brought to the forefront in the field of sensing. Recently, a number of reports have demonstrated that graphene–nanoparticle hybrid structures can act synergistically to offer a number of unique physicochemical properties that are desirable and advantageous for sensing applications. These graphene–nanoparticle hybrid structures are particularly interesting because not only do they display the individual properties of the nanoparticles and of graphene, but they can also exhibit additional synergistic properties thereby enhancing the achievable sensitivity and selectivity using a variety of sensing mechanisms. As such, in this perspective, we will discuss the progress that has been made in the development and application of graphene–nanoparticle hybrid sensors and their future prospects. In particular, we will focus on the preparation of graphene–nanoparticle hybrid structures as well as their application in electronic, electrochemical, and optical sensors. PMID:23828095

Additively manufactured biodegradable porous magnesium.

PubMed

Li, Y; Zhou, J; Pavanram, P; Leeflang, M A; Fockaert, L I; Pouran, B; Tümer, N; Schröder, K-U; Mol, J M C; Weinans, H; Jahr, H; Zadpoor, A A

2018-02-01

An ideal bone substituting material should be bone-mimicking in terms of mechanical properties, present a precisely controlled and fully interconnected porous structure, and degrade in the human body to allow for full regeneration of large bony defects. However, simultaneously satisfying all these three requirements has so far been highly challenging. Here we present topologically ordered porous magnesium (WE43) scaffolds based on the diamond unit cell that were fabricated by selective laser melting (SLM) and satisfy all the requirements. We studied the in vitro biodegradation behavior (up to 4 weeks), mechanical properties and biocompatibility of the developed scaffolds. The mechanical properties of the AM porous WE43 (E = 700-800 MPa) scaffolds were found to fall into the range of the values reported for trabecular bone even after 4 weeks of biodegradation. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), electrochemical tests and µCT revealed a unique biodegradation mechanism that started with uniform corrosion, followed by localized corrosion, particularly in the center of the scaffolds. Biocompatibility tests performed up to 72 h showed level 0 cytotoxicity (according to ISO 10993-5 and -12), except for one time point (i.e., 24 h). Intimate contact between cells (MG-63) and the scaffolds was also observed in SEM images. The study shows for the first time that AM of porous Mg may provide distinct possibilities to adjust biodegradation profile through topological design and open up unprecedented opportunities to develop multifunctional bone substituting materials that mimic bone properties and enable full regeneration of critical-size load-bearing bony defects. The ideal biomaterials for bone tissue regeneration should be bone-mimicking in terms of mechanical properties, present a fully interconnected porous structure, and exhibit a specific biodegradation behavior to enable full regeneration of bony defects. Recent advances in additive manufacturing have resulted in biomaterials that satisfy the first two requirements but simultaneously satisfying the third requirement has proven challenging so far. Here we present additively manufactured porous magnesium structures that have the potential to satisfy all above-mentioned requirements. Even after 4 weeks of biodegradation, the mechanical properties of the porous structures were found to be within those reported for native bone. Moreover, our comprehensive electrochemical, mechanical, topological, and biological study revealed a unique biodegradation behavior and the limited cytotoxicity of the developed biomaterials. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

An Electrochemical Study on the Copolymer Formed from Piperazine and Aniline Monomers.

PubMed

Dkhili, Samiha; López-Bernabeu, Sara; Kedir, Chahineze Nawel; Huerta, Francisco; Montilla, Francisco; Besbes-Hentati, Salma; Morallon, Emilia

2018-06-14

A study on the electrochemical oxidation of piperazine and its electrochemical copolymerization with aniline in acidic medium is presented. It was found that the homopolymerization of piperazine cannot be achieved under electrochemical conditions. A combination of electrochemistry, in situ Fourier transform infrared (FTIR), and ex situ X-ray photoelectron spectroscopy (XPS) spectroscopies was used to characterize both the chemical structure and the redox behavior of an electrochemically synthesized piperazine⁻aniline copolymer. The electrochemical sensing properties of the deposited material were also tested against ascorbic acid and dopamine as redox probes.

Spectroscopic and Electrochemical Properties of Lithium-Rich LiFePO4 Cathode Synthesized by Solid-State Reaction

NASA Astrophysics Data System (ADS)

Rosaiah, P.; Hussain, O. M.; Zhu, Jinghui; Qiu, Yejun

2017-08-01

Lithium iron phosphate (Li x FePO4) is synthesized by a solid-state reaction method. The structural, electrical and electrochemical properties are studied in detail. It is found that the increment of lithium concentration (up to x = 1.05) does not affect the structure of LiFePO4 but improves its electrical conductivity as well as electrochemical performance. Surface morphological studies exhibited the formation of rod-like nanoparticles with small size. Electric and dielectric properties are also investigated over a frequency range of 1 Hz-1 MHz at different temperatures. The conductivity increased with increasing temperature, which follows the Arrhenius relation with the activation energy of about 0.31 eV. And the electrochemical tests found that the Li1.05FePO4 cathode possessed improved discharge capacity with better cycling performance.

Evaluating the trade-off between mechanical and electrochemical performance of separators for lithium-ion batteries: Methodology and application

NASA Astrophysics Data System (ADS)

Plaimer, Martin; Breitfuß, Christoph; Sinz, Wolfgang; Heindl, Simon F.; Ellersdorfer, Christian; Steffan, Hermann; Wilkening, Martin; Hennige, Volker; Tatschl, Reinhard; Geier, Alexander; Schramm, Christian; Freunberger, Stefan A.

2016-02-01

Lithium-ion batteries are in widespread use in electric vehicles and hybrid vehicles. Besides features like energy density, cost, lifetime, and recyclability the safety of a battery system is of prime importance. The separator material impacts all these properties and requires therefore an informed selection. The interplay between the mechanical and electrochemical properties as key selection criteria is investigated. Mechanical properties were investigated using tensile and puncture penetration tests at abuse relevant conditions. To investigate the electrochemical performance in terms of effective conductivity a method based on impedance spectroscopy was introduced. This methodology is applied to evaluate ten commercial separators which allows for a trade-off analysis of mechanical versus electrochemical performance. Based on the results, and in combination with other factors, this offers an effective approach to select suitable separators for automotive applications.

Improvement of the electrochemical properties via poly(3,4-ethylenedioxythiophene) oriented micro/nanorods

NASA Astrophysics Data System (ADS)

Li, Yu; Wang, Bichen; Chen, Huimin; Feng, Wei

Arrays of oriented poly(3,4-ethylenedioxythiophene) (PEDOT) micro/nanorods are synthesized by electrochemical galvanostatic method at the current density of 1 mA cm -2 in the cetyltrimethylammonium bromide (CTAB) aqueous solution whose pH value is 1. The CTAB is used both as the surfactant and the supporting salt in the electrolyte solution. The electrochemical properties of PEDOT films are characterized by cyclic voltammetry and galvanostatic charge/discharge techniques, which indicate that the arrays of oriented PEDOT micro/nanorods can be applied as the electrode materials of supercapacitors. In addition, the cycling performance of PEDOT micro/nanorods is much better than that of traditional PEDOT particles. The effects of the concentration of CTAB, the current density, and pH value of electrolyte solutions on the morphologies and electrochemical properties of PEDOT films are investigated. The mechanism of different morphologies formation is discussed in this study as well.

Current Progress of Nanomaterials in Molecularly Imprinted Electrochemical Sensing.

PubMed

Zhong, Chunju; Yang, Bin; Jiang, Xinxin; Li, Jianping

2018-01-02

Nanomaterials have received much attention during the past decade because of their excellent optical, electronic, and catalytic properties. Nanomaterials possess high chemical reactivity, also high surface energy. Thus, provide a stable immobilization platform for biomolecules, while preserving their reactivity. Due to the conductive and catalytic properties, nanomaterials can also enhance the sensitivity of molecularly imprinted electrochemical sensors by amplifying the electrode surface, increasing the electron transfer, and catalyzing the electrochemical reactions. Molecularly imprinted polymers that contain specific molecular recognition sites can be designed for a particular target analyte. Incorporating nanomaterials into molecularly imprinted polymers is important because nanomaterials can improve the response signal, increase the sensitivity, and decrease the detection limit of the sensors. This study describes the classification of nanomaterials in molecularly imprinted polymers, their analytical properties, and their applications in the electrochemical sensors. The progress of the research on nanomaterials in molecularly imprinted polymers and the application of nanomaterials in molecularly imprinted polymers is also reviewed.

Effects of Salts and Metal Oxides on Electrochemical and Optical Properties of Streptococcus mutans

NASA Astrophysics Data System (ADS)

Kawai, Tsuyoshi; Nagame, Seigo; Kambara, Masaki; Yoshino, Katsumi

1994-10-01

The effects of calcium salts and metal oxide powders on electrochemical, optical and biological properties of Streptococcus mutans have been studied as a novel method to determine the strain. Electrochemical signals of Streptococcus mutans show remarkable decrease in the presence of saturated calcium salts such as CaHPO4, Ca3(PO4)2, and Ca5(PO4)3OH depending on the strains of Streptococcus mutans: Ingbritt, NCTC-10449, or GS-5. The number of viable cells also decreases upon addition of these powders. The effects of metal oxides such as ZnO and BaTiO3 on the electrochemical characteristics and photoluminescence of Streptococcus mutans have also been studied.

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.

Recent advances in electrochemical biosensors based on graphene two-dimensional nanomaterials.

PubMed

Song, Yang; Luo, Yanan; Zhu, Chengzhou; Li, He; Du, Dan; Lin, Yuehe

2016-02-15

Graphene as a star among two-dimensional nanomaterials has attracted tremendous research interest in the field of electrochemistry due to their intrinsic properties, including the electronic, optical, and mechanical properties associated with their planar structure. The marriage of graphene and electrochemical biosensors has created many ingenious biosensing strategies for applications in the areas of clinical diagnosis and food safety. This review provides a comprehensive overview of the recent advances in the development of graphene based electrochemical biosensors. Special attention is paid to graphene-based enzyme biosensors, immunosensors, and DNA biosensors. Future perspectives on high-performance graphene-based electrochemical biosensors are also discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermodynamic and Kinetic Properties of the Electrochemical Cell.

ERIC Educational Resources Information Center

Smith, Donald E.

1983-01-01

Describes basic characteristics of the electrochemical cell. Also describes basic principles of electrochemical procedures and use of these concepts to explain use of the term "primarily" in discussions of methods primarily responsive to equilibrium cell potential, bulk ohmic resistance, and the Faradaic impedance. (JN)

Synthesis of Gold Nanoparticles with Buffer-Dependent Variations of Size and Morphology in Biological Buffers.

PubMed

Ahmed, Syed Rahin; Oh, Sangjin; Baba, Rina; Zhou, Hongjian; Hwang, Sungu; Lee, Jaebeom; Park, Enoch Y

2016-12-01

The demand for biologically compatible and stable noble metal nanoparticles (NPs) has increased in recent years due to their inert nature and unique optical properties. In this article, we present 11 different synthetic methods for obtaining gold nanoparticles (Au NPs) through the use of common biological buffers. The results demonstrate that the sizes, shapes, and monodispersity of the NPs could be varied depending on the type of buffer used, as these buffers acted as both a reducing agent and a stabilizer in each synthesis. Theoretical simulations and electrochemical experiments were performed to understand the buffer-dependent variations of size and morphology exhibited by these Au NPs, which revealed that surface interactions and the electrostatic energy on the (111) surface of Au were the determining factors. The long-term stability of the synthesized NPs in buffer solution was also investigated. Most NPs synthesized using buffers showed a uniquely wide range of pH stability and excellent cell viability without the need for further modifications.

Enhanced Intrinsic Catalytic Activity of λ-MnO2 by Electrochemical Tuning and Oxygen Vacancy Generation.

PubMed

Lee, Sanghan; Nam, Gyutae; Sun, Jie; Lee, Jang-Soo; Lee, Hyun-Wook; Chen, Wei; Cho, Jaephil; Cui, Yi

2016-07-18

Chemically prepared λ-MnO2 has not been intensively studied as a material for metal-air batteries, fuel cells, or supercapacitors because of their relatively poor electrochemical properties compared to α- and δ-MnO2 . Herein, through the electrochemical removal of lithium from LiMn2 O4 , highly crystalline λ-MnO2 was prepared as an efficient electrocatalyst for the oxygen reduction reaction (ORR). The ORR activity of the material was further improved by introducing oxygen vacancies (OVs) that could be achieved by increasing the calcination temperature during LiMn2 O4 synthesis; a concentration of oxygen vacancies in LiMn2 O4 could be characterized by its voltage profile as the cathode in a lithiun-metal half-cell. λ-MnO2-z prepared with the highest OV exhibited the highest diffusion-limited ORR current (5.5 mA cm(-2) ) among a series of λ-MnO2-z electrocatalysts. Furthermore, the number of transferred electrons (n) involved in the ORR was >3.8, indicating a dominant quasi-4-electron pathway. Interestingly, the catalytic performances of the samples were not a function of their surface areas, and instead depended on the concentration of OVs, indicating enhancement in the intrinsic catalytic activity of λ-MnO2 by the generation of OVs. This study demonstrates that differences in the electrochemical behavior of λ-MnO2 depend on the preparation method and provides a mechanism for a unique catalytic behavior of cubic λ-MnO2 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Peculiarities of steel and alloy electrochemical and corrosion behavior after laser processing

NASA Astrophysics Data System (ADS)

Kuzmenko, Tat'yana G.; Kosyrev, Feliks K.; Rodin, Anatoly V.; Sayapin, V. P.

1997-04-01

Different types of laser processing can significantly increase the corrosion resistance of constructive materials, secure higher levels of metal properties in comparison with standard protection from corrosion and can be successfully used for industrial application. The research carried out in TRINITI during the last 10 years allowed us to create a data base about corrosion behavior in different chemical media of various metals, alloys and steels after welding, melting, surface alloying, etc. on technological continuous-wave carbon-dioxide-laser with average power up to 5 kilowatt. The investigated materials were subdivided into two groups: (1) without changes of phases composition after laser processing (pure metals, stainless steels); and (2) exposed to structural and phase changes under laser-matter interaction (carbon steels with different carbon content). It has allowed us to investigate the peculiarities of corrosion process mechanism depending on matter surface structure and phase composition both on laser irradiation regimes. Our research was based on the high sensitive electrochemical analysis combined with other corrosion and physical methods. The essential principles of electrochemical analysis are next. There are two main processes on metal under the interaction with electrolyte solution: anodic reaction -- which means the metal oxidation or transition of metal kations into solution; cathodic reaction -- the reoxidation of the ions or molecular of the solution. They are characterizing by the values of current densities and the rates of these reactions are dependent upon the potential arising on the metal-solution frontier. The electrochemical reactions kinetic investigations gives a unique possibility for the research of metal structure and corrosion behavior even in the case of small thickness of laser processed layers.

Preparation and electrochemical properties of mesoporous NiCo2O4 double-hemisphere used as anode for lithium-ion battery.

PubMed

Yang, Yue; Huang, Guo Yong; Sun, Hongyu; Ahmad, Mashkoor; Mou, Qinyao; Zhang, Hongmei

2018-06-19

NiCo 2 O 4 is a potential anode material for lithium ion battery due to its many advantages, such as high theoretical capacitance, low cost, and good electrochemical activity. In this study, mesoporous NiCo 2 O 4 double-hemisphere (3-5 μm) with high surface area (270.68 m 2 ·g -1 ) and excellent electrochemical performances has been synthesized through a facile precipitation method followed with thermal treatment process. The prepared NiCo 2 O 4 is pure phase and can be indexed as a face-centered-cubic with a typical spinel structure. Electrochemical tests show the prepared material has high specific capacities (910 mAh·g -1 at 100 mA·g -1 ), excellent cyclicity (908  mAh·g -1 at 100 mA·g -1 after 60 cycles) and remarkable high rate performance (after 100 cycles, 585 mAh·g -1 at 400 mAh·g -1 , 415 mAh·g -1 at 800 mAh·g -1 and 320 mAh·g -1 at 1600 mAh·g -1 with coulombic efficiencies of almost 100%). The excellent performances of prepared NiCo 2 O 4 are mainly caused by the unique double-hemisphere structure, which has large surface area, gives material more opportunity to contact with electrolyte and facilitates lithium ion spreading into the material along the radical direction, resulting in a promising application for next-generation lithium-ion batteries. Copyright © 2018 Elsevier Inc. All rights reserved.

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).

Selectivity control of carbonylation of methanol to dimethyl oxalate and dimethyl carbonate over gold anode by electrochemical potential.

PubMed

Funakawa, Akiyasu; Yamanaka, Ichiro; Takenaka, Sakae; Otsuka, Kiyoshi

2004-05-05

New and unique electrocatalysis of gold for the carbonylation of methanol to dimethyl oxalate (DMO) and dimethyl carbonate (DMC) was found. The selectivity to DMO and DMC could be controlled over gold anode by electrochemical potential, as you like. Drastic changes of gold electrocatalysis was due to changes of the oxidation state of gold, Au0 or Au3+.

Enhanced catalytic and dopamine sensing properties of electrochemically reduced conducting polymer nanocomposite doped with pure graphene oxide.

PubMed

Wang, Wenting; Xu, Guiyun; Cui, Xinyan Tracy; Sheng, Ge; Luo, Xiliang

2014-08-15

Significantly enhanced catalytic activity of a nanocomposite composed of conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) doped with graphene oxide (GO) was achieved through a simple electrochemical reduction process. The nanocomposite (PEDOT/GO) was electrodeposited on an electrode and followed by electrochemical reduction, and the obtained reduced nanocomposite (PEDOT/RGO) modified electrode exhibited lowered electrochemical impedance and excellent electrocatalytic activity towards the oxidation of dopamine. Based on the excellent catalytic property of PEDOT/RGO, an electrochemical sensor capable of sensitive and selective detection of DA was developed. The fabricated sensor can detect DA in a wide linear range from 0.1 to 175μM, with a detection limit of 39nM, and it is free from common interferences such as uric acid and ascorbic acid. Copyright © 2014 Elsevier B.V. All rights reserved.

Nanoparticles and DNA - a powerful and growing functional combination in bionanotechnology

NASA Astrophysics Data System (ADS)

Samanta, Anirban; Medintz, Igor L.

2016-04-01

Functionally integrating DNA and other nucleic acids with nanoparticles in all their different physicochemical forms has produced a rich variety of composite nanomaterials which, in many cases, display unique or augmented properties due to the synergistic activity of both components. These capabilities, in turn, are attracting greater attention from various research communities in search of new nanoscale tools for diverse applications that include (bio)sensing, labeling, targeted imaging, cellular delivery, diagnostics, therapeutics, theranostics, bioelectronics, and biocomputing to name just a few amongst many others. Here, we review this vibrant and growing research area from the perspective of the materials themselves and their unique capabilities. Inorganic nanocrystals such as quantum dots or those made from gold or other (noble) metals along with metal oxides and carbon allotropes are desired as participants in these hybrid materials since they can provide distinctive optical, physical, magnetic, and electrochemical properties. Beyond this, synthetic polymer-based and proteinaceous or viral nanoparticulate materials are also useful in the same role since they can provide a predefined and biocompatible cargo-carrying and targeting capability. The DNA component typically provides sequence-based addressability for probes along with, more recently, unique architectural properties that directly originate from the burgeoning structural DNA field. Additionally, DNA aptamers can also provide specific recognition capabilities against many diverse non-nucleic acid targets across a range of size scales from ions to full protein and cells. In addition to appending DNA to inorganic or polymeric nanoparticles, purely DNA-based nanoparticles have recently surfaced as an excellent assembly platform and have started finding application in areas like sensing, imaging and immunotherapy. We focus on selected and representative nanoparticle-DNA materials and highlight their myriad applications using examples from the literature. Overall, it is clear that this unique functional combination of nanomaterials has far more to offer than what we have seen to date and as new capabilities for each of these materials are developed, so, too, will new applications emerge.

Method for making an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.; Pal, Uday B.

1996-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is provided.

Electrochemical modification of properties of ZnO films

NASA Astrophysics Data System (ADS)

Abe, Koji; Okubo, Takamasa; Ishikawa, Hirohito

2017-12-01

The properties of Al-doped ZnO films and Li- and Al-doped ZnO films were modified by electrochemical treatment. A constant current was applied between a ZnO film and a Pt electrode in an electrolyte solution. The sheet resistance of the ZnO film increased and decreased depending on the direction of current flow during the electrochemical treatment. When the ZnO film was used as a cathode (forward biased condition), the sheet resistance of the ZnO film decreased with increasing treatment time. The optical bandgap of the H2-annealed ZnO film also depended on the direction of current flow and increased under the forward biased condition. The electrochemical treatment caused the Burstein-Moss effect.

The tribocorrosion behaviour of NiTi alloy

NASA Astrophysics Data System (ADS)

Kosec, Tadeja; Močnik, Petra; Legat, Andraž

2014-01-01

In biomedical applications, NiTi alloys are used mainly because of their favourable shape memory and superelastic properties. However, in many applications the tribocorrosion properties of these alloys can be of critical concern. For this reason the electrochemical and tribocorrosion properties of superelastic NiTi sheet and orthodontic archwire were studied, taking into account their microstructures and the effect of different surface finishes. In the case of the electrochemical tests, samples were tested in artificial saliva, whereas in the tribocorrosion tests the experiments were performed in ambient air, distilled water, and artificial saliva, the latter as a corrosive medium. In these tests, the total wear rate of the alloy samples was determined, together with the corresponding chemical and tribological contributions. It was confirmed that the microstructure of the investigated alloys had a significant effect on the measured electrochemical and tribocorrosion properties.

Nitrogen-doped graphene: effect of graphite oxide precursors and nitrogen content on the electrochemical sensing properties.

PubMed

Megawati, Monica; Chua, Chun Kiang; Sofer, Zdenek; Klímová, Kateřina; Pumera, Martin

2017-06-21

Graphene, produced via chemical methods, has been widely applied for electrochemical sensing due to its structural and electrochemical properties as well as its ease of production in large quantity. While nitrogen-doped graphenes are widely studied materials, the literature showing an effect of graphene oxide preparation methods on nitrogen quantity and chemical states as well as on defects and, in turn, on electrochemical sensing is non-existent. In this study, the properties of nitrogen-doped graphene materials, prepared via hydrothermal synthesis using graphite oxide produced by various classical methods using permanganate or chlorate oxidants Staudenmaier, Hummers, Hofmann and Brodie oxidation methods, were studied; the resulting nitrogen-doped graphene oxides were labeled as ST-GO, HU-GO, HO-GO and BR-GO, respectively. The electrochemical oxidation of biomolecules, such as ascorbic acid, uric acid, dopamine, nicotinamide adenine nucleotide and DNA free bases, was carried out using cyclic voltammetry and differential pulse voltammetry techniques. The nitrogen content in doped graphene oxides increased in the order ST-GO < BR-GO < HO-GO < HU-GO. In the same way, the pyridinic form of nitrogen increased and the electrocatalytic effect of N-doped graphene followed this trend, as shown in the cyclic voltammograms. This is a very important finding that provides insight into the electrocatalytic effect of N-doped graphene. The nitrogen-doped graphene materials exhibited improved sensitivity over bare glassy carbon for ascorbic acid, uric acid and dopamine detection. These studies will enhance our understanding of the effects of graphite oxide precursors on the electrochemical sensing properties of nitrogen-doped graphene materials.

Nature of the Electrochemical Properties of Sulphur Substituted LiMn2O4 Spinel Cathode Material Studied by Electrochemical Impedance Spectroscopy

PubMed Central

Bakierska, Monika; Świętosławski, Michał; Dziembaj, Roman; Molenda, Marcin

2016-01-01

In this work, nanostructured LiMn2O4 (LMO) and LiMn2O3.99S0.01 (LMOS1) spinel cathode materials were comprehensively investigated in terms of electrochemical properties. For this purpose, electrochemical impedance spectroscopy (EIS) measurements as a function of state of charge (SOC) were conducted on a representative charge and discharge cycle. The changes in the electrochemical performance of the stoichiometric and sulphur-substituted lithium manganese oxide spinels were examined, and suggested explanations for the observed dependencies were given. A strong influence of sulphur introduction into the spinel structure on the chemical stability and electrochemical characteristic was observed. It was demonstrated that the significant improvement in coulombic efficiency and capacity retention of lithium cell with LMOS1 active material arises from a more stable solid electrolyte interphase (SEI) layer. Based on EIS studies, the Li ion diffusion coefficients in the cathodes were estimated, and the influence of sulphur on Li+ diffusivity in the spinel structure was established. The obtained results support the assumption that sulphur substitution is an effective way to promote chemical stability and the electrochemical performance of LiMn2O4 cathode material. PMID:28773819

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.

Effect of ZnO core electrodeposition conditions on electrochemical and photocatalytic properties of polypyrrole-graphene oxide shelled nanoarrays

NASA Astrophysics Data System (ADS)

Pruna, A.; Shao, Q.; Kamruzzaman, M.; Li, Y. Y.; Zapien, J. A.; Pullini, D.; Busquets Mataix, D.; Ruotolo, A.

2017-01-01

Novel hybrid core-shell nanoarchitectures were fabricated by a simple two-step electrochemical approach: first ZnO nanorod core was electrodeposited from Zn(NO3)2 solution; further, the core nanoarray was coated with a shell based on polypyrrole hybridized with graphene oxide by electropolymerization. The properties of the core/shell nanoarchitectures were studied as a function of the core properties induced by electrodeposition parameters. The ZnO nanostructures showed improved crystallinity and c-axis preferred orientation with increasing cathodic deposition potential while the increased deposition duration resulted in a morphology transition from nanorod to pyramidal shape. The electrochemical activity of the core/shell arrays was found to increase with the deposition potential of ZnO core but decreased when morphology changed from nanorod to pyramid shape. The photocatalytic results showed improved activity for the core/hybrid shell nanoarrays with respect to ZnO and ZnO/PPy ones. The degradation rate for methylene blue decreased with prolonged deposition duration of the core. The obtained results highlight the importance of electrochemical tuning of ZnO-based core/shell nanoarrays for improved performance in electrochemical and photocatalytic applications.

Preparation and Characterization of Mesoporous Nickel derived from Liquid crystalline Template and Evaluation of its Electro catalytic activity towards Methanol Oxidation

NASA Astrophysics Data System (ADS)

Mohanapriya, S.; Renuka devi, R.; Raj, V.

2018-02-01

Mesoporous Nickel has been prepared by electrodeposition using non-ionic surfactant based liquid crystalline template under optimized processing conditions. Physico-chemical properties of mesoporous nickel is systematically characterized through XRD, SEM and AFM analyses. Comparison of electrocatalytic activity of mesoporous nickel with smooth nickel was interrogated using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) analyses. Distinctly enhanced electrocatalytic activity with improved surface poisoning resistance related to mesoporous nickel electrode towards methanol oxidation stems from unique mesoporous morphology. This mesoporous morphology with high surface to volume ratio is highly beneficial to promote active catalytic centers to offer readily accessible Pt catalytic sites for MOR, through facilitating mass and electron transports.

An overview of the applications of graphene-based materials in supercapacitors.

PubMed

Huang, Yi; Liang, Jiajie; Chen, Yongsheng

2012-06-25

Due to their unique 2D structure and outstanding intrinsic physical properties, such as extraordinarily high electrical conductivity and large surface area, graphene-based materials exhibit great potential for application in supercapacitors. In this review, the progress made so far for their applications in supercapacitors is reviewed, including electrochemical double-layer capacitors, pseudo-capacitors, and asymmetric supercapacitors. Compared with traditional electrode materials, graphene-based materials show some novel characteristics and mechanisms in the process of energy storage and release. Several key issues for improving the structure of graphene-based materials and for achieving better capacitor performance, along with the current outlook for the field, are also discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-performance Fuel Cell with Stretched Catalyst-Coated Membrane: One-step Formation of Cracked Electrode.

PubMed

Kim, Sang Moon; Ahn, Chi-Yeong; Cho, Yong-Hun; Kim, Sungjun; Hwang, Wonchan; Jang, Segeun; Shin, Sungsoo; Lee, Gunhee; Sung, Yung-Eun; Choi, Mansoo

2016-05-23

We have achieved performance enhancement of polymer electrolyte membrane fuel cell (PEMFC) though crack generation on its electrodes. It is the first attempt to enhance the performance of PEMFC by using cracks which are generally considered as defects. The pre-defined, cracked electrode was generated by stretching a catalyst-coated Nafion membrane. With the strain-stress property of the membrane that is unique in the aspect of plastic deformation, membrane electrolyte assembly (MEA) was successfully incorporated into the fuel cell. Cracked electrodes with the variation of strain were investigated and electrochemically evaluated. Remarkably, mechanical stretching of catalyst-coated Nafion membrane led to a decrease in membrane resistance and an improvement in mass transport, which resulted in enhanced device performance.

Conducting Polymer Nanostructures: Template Synthesis and Applications in Energy Storage

PubMed Central

Pan, Lijia; Qiu, Hao; Dou, Chunmeng; Li, Yun; Pu, Lin; Xu, Jianbin; Shi, Yi

2010-01-01

Conducting polymer nanostructures have received increasing attention in both fundamental research and various application fields in recent decades. Compared with bulk conducting polymers, conducting polymer nanostructures are expected to display improved performance in energy storage because of the unique properties arising from their nanoscaled size: high electrical conductivity, large surface area, short path lengths for the transport of ions, and high electrochemical activity. Template methods are emerging for a sort of facile, efficient, and highly controllable synthesis of conducting polymer nanostructures. This paper reviews template synthesis routes for conducting polymer nanostructures, including soft and hard template methods, as well as its mechanisms. The application of conducting polymer mesostructures in energy storage devices, such as supercapacitors and rechargeable batteries, are discussed. PMID:20717527

Conducting polymer nanostructures: template synthesis and applications in energy storage.

PubMed

Pan, Lijia; Qiu, Hao; Dou, Chunmeng; Li, Yun; Pu, Lin; Xu, Jianbin; Shi, Yi

2010-07-02

Conducting polymer nanostructures have received increasing attention in both fundamental research and various application fields in recent decades. Compared with bulk conducting polymers, conducting polymer nanostructures are expected to display improved performance in energy storage because of the unique properties arising from their nanoscaled size: high electrical conductivity, large surface area, short path lengths for the transport of ions, and high electrochemical activity. Template methods are emerging for a sort of facile, efficient, and highly controllable synthesis of conducting polymer nanostructures. This paper reviews template synthesis routes for conducting polymer nanostructures, including soft and hard template methods, as well as its mechanisms. The application of conducting polymer mesostructures in energy storage devices, such as supercapacitors and rechargeable batteries, are discussed.

Metal-organic frameworks for lithium ion batteries and supercapacitors

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

Ke, Fu-Sheng; Wu, Yu-Shan; Deng, Hexiang, E-mail: hdeng@whu.edu.cn

2015-03-15

Porous materials have been widely used in batteries and supercapacitors attribute to their large internal surface area (usually 100–1000 m{sup 2} g{sup −1}) and porosity that can favor the electrochemical reaction, interfacial charge transport, and provide short diffusion paths for ions. As a new type of porous crystalline materials, metal-organic frameworks (MOFs) have received huge attention in the past decade due to their unique properties, i.e. huge surface area (up to 7000 m{sup 2} g{sup −1}), high porosity, low density, controllable structure and tunable pore size. A wide range of applications including gas separation, storage, catalysis, and drug delivery benefitmore » from the recent fast development of MOFs. However, their potential in electrochemical energy storage has not been fully revealed. Herein, the present mini review appraises recent and significant development of MOFs and MOF-derived materials for rechargeable lithium ion batteries and supercapacitors, to give a glimpse into these potential applications of MOFs. - Graphical abstract: MOFs with large surface area and high porosity can offer more reaction sites and charge carriers diffusion path. Thus MOFs are used as cathode, anode, electrolyte, matrix and precursor materials for lithium ion battery, and also as electrode and precursor materials for supercapacitors. - Highlights: • MOFs have potential in electrochemical area due to their high porosity and diversity. • We summarized and compared works on MOFs for lithium ion battery and supercapacitor. • We pointed out critical challenges and provided possible solutions for future study.« less

Characterization of chemical interactions during chemical mechanical polishing (CMP) of copper

NASA Astrophysics Data System (ADS)

Lee, Seung-Mahn

2003-10-01

Chemical mechanical polishing (CMP) has received much attention as an unique technique to provide a wafer level planarization in semiconductor manufacturing. However, despite the extensive use of CMP, it still remains one of the least understood areas in semiconductor processing. The lack of the fundamental understanding is a significant barrier to further advancements in CMP technology. One critical aspect of metal CMP is the formation of a thin surface layer on the metal surface. The formation and removal of this layer controls all the aspects of the CMP process, including removal rate, surface finish, etc. In this dissertation, we focus on the characterization of the formation and removal of the thin surface layer on the copper surface. The formation dynamics was investigated using static and dynamic electrochemical techniques, including potentiodynamic scans and chronoamperometry. The results were validated using XPS measurements. The mechanical properties of the surface layer were investigated using nanoindentation measurements. The electrochemical investigation showed that the thickness of the surface layer is controlled by the chemicals such as an oxidizer (hydrogen peroxide), a corrosion inhibitor (benzotriazole), a complexing agent (citric acid), and their concentrations. The dynamic electrochemical measurements indicated that the initial layer formation kinetics is unaffected by the corrosion inhibitors. The passivation due to the corrosion inhibitor becomes important only on large time scales (>200 millisecond). The porosity and the density of the chemically modified surface layer can be affected by additives of other chemicals such as citric acid. An optimum density of the surface layer is required for high polishing rate while at the same time maintaining a high degree of surface finish. Nanoindentation measurements indicated that the mechanical properties of the surface layer are strongly dependent on the chemical additives in the slurry. The CMP removal rates were found to be in good agreement with the initial reaction kinetics as well as the mechanical properties of the chemically modified surface layer. In addition, the material removal model based on the micro- and nano-scale interactions, which were measured experimentally, has been developed.

Electrochemical Properties of Si Film Electrodes Containing TiNi Thin-Film Current Collectors

NASA Astrophysics Data System (ADS)

Im, Yeon-min; Noh, Jung-pil; Cho, Gyu-bong; Nam, Tea-hyun

2018-03-01

A 50.3Ti-49.7Ni thin film fabricated by DC sputtering was employed as a current collector of Si film electrode. The structural and electrochemical properties of Si/TiNi film electrode were compared with those of a Si/Cu film electrode. The TiNi film with cluster-like structures composed of B2 austenitic phase at room temperature displayed the high electrochemical stability for Li ions. The amorphous Si film deposited on the TiNi film also consisted of cluster-like structures on the surface. The Si film grown on the TiNi film current collector (Si/TiNi electrode) demonstrated a high columbic efficiency of 87% at the first cycle (363 μAh/cm2 of charge capacity and 314 μAh/cm2 of discharge capacity). The Si/TiNi electrode exhibited better electrochemical properties in terms of capacity, cycle performance, and structural stability compared to the Si electrode with a conventional Cu foil current collector.

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.

1995-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided.

In-situ electrical, mechanical and electrochemical characterizations of one-dimensional nanostructures

NASA Astrophysics Data System (ADS)

Mir Shah Ghassemi, Seyyed Hessam

One-dimensional nanostructures initiated new aspects to the materials applications due to their superior properties compared to the bulk materials. Properties of nanostructures have been characterized by many techniques and used for various device applications. However, simultaneous correlation between the physical and structural properties of these nanomaterials has not been widely investigated. Therefore, it is necessary to perform in-situ study on the physical and structural properties of nanomaterials to understand their relation. In this work, we will use a unique instrument to perform real time atomic force microscopy (AFM) and scanning tunneling microscopy (STM) of nanomaterials inside a transmission electron microscopy (TEM) system. This AFM/STM-TEM system is used to investigate the mechanical, electrical, and electrochemical properties of boron nitride nanotubes (BNNTs) and Silicon nanorods (SiNRs). BNNTs are one of the subjects of this PhD research due to their comparable, and in some cases superior, properties compared to carbon nanotubes. Therefore, to further develop their applications, it is required to investigate these characteristics in atomic level. In this research, the mechanical properties of multi-walled BNNTs were first studied. Several tests were designed to study and characterize their real-time deformation behavior to the applied force. Observations revealed that BNNTs possess highly flexible structures under applied force. Detailed studies were then conducted to understand the bending mechanism of the BNNTs. Formations of reversible ripples were observed and described in terms of thermodynamic energy of the system. Fracture failure of BNNTs were initiated at the outermost walls and characterized to be brittle. Second, the electrical properties of individual BNNTs were studied. Results showed that the bandgap and electronic properties of BNNTs can be engineered by means of applied strain. It was found that the conductivity, electron concentration and carrier mobility of BNNTs can be tuned as a function of applied stress. Although, BNNTs are considered to be candidate for field emission applications, observations revealed that their properties degrade upon cycles of emissions. Results showed that due to the high emission current density, the temperature of the sample was increased and reached to the decomposition temperature at which the B-N bonds start to break. In addition to BNNTs, we have also performed in-situ study on the electrochemical properties of silicon nanorods (SiNRs). Specifically, lithiation and delithiation of SiNRs were studied by our STM-TEM system. Our observations showed the direct formation of Li22Si 5 phases as a result of lithium intercalation. Radial expansion of the anode materials were observed and characterized in terms of size-scale. Later, the formation and growth of the lithium fibers on the surface of the anode materials were observed and studied. Results revealed the formation of lithium islands inside the ionic liquid electrolyte which then grew as Li dendrite toward the cathode material.

Thermally responsive polymer electrolytes for inherently safe electrochemical energy storage

NASA Astrophysics Data System (ADS)

Kelly, Jesse C.

Electrochemical double layer capacitors (EDLCs), supercapacitors and Li-ion batteries have emerged as premier candidates to meet the rising demands in energy storage; however, such systems are limited by thermal hazards, thermal runaway, fires and explosions, all of which become increasingly more dangerous in large-format devices. To prevent such scenarios, thermally-responsive polymer electrolytes (RPEs) that alter properties in electrochemical energy storage devices were designed and tested. These RPEs will be used to limit or halt device operation when temperatures increase beyond a predetermined threshold, therefore limiting further heating. The development of these responsive systems will offer an inherent safety mechanism in electrochemical energy storage devices, while preserving the performance, lifetimes, and versatility that large-format systems require. Initial work focused on the development of a model system that demonstrated the concept of RPEs in an electrochemical device. Aqueous electrolyte solutions of polymers exhibiting properties that change in response to temperature were developed for applications in EDLCs and supercapacitors. These "smart materials" provide a means to control electrochemical systems where polymer phase separation at high temperatures affects electrolyte properties and inhibits device performance. Aqueous RPEs were synthesized using N-isopropylacrylamide, which governs the thermal properties, and fractions of acrylic acid or vinyl sulfonic acids, which provide ions to the solution. The molecular properties of these aqueous RPEs, specifically the ionic composition, were shown to influence the temperature-dependent electrolyte properties and the extent to which these electrolytes control the energy storage characteristics of a supercapacitor device. Materials with high ionic content provided the highest room temperature conductivity and electrochemical activity; however, RPEs with low ionic content provided the highest "on-off" ratio in electrochemical activity at elevated temperatures. Overall, solution pH and conductivity were altered by an order of magnitude and device performance (ability to store charge) decreased by over 70%. After demonstration of a model responsive electrolyte in an aqueous system, ionic liquid (IL) based electrolytes were developed as a means of controlling the electrochemical performance in the non-aqueous environments that batteries, specifically Li-ion, require. Here, two systems were developed: (1) an electrolyte comprising poly(ethylene oxide) (PEO), the IL, [EMIM][BF4], and a lithium salt and (2) an electrolyte comprising poly(benzyl methacrylate) (PBzMA), the IL, [EMIM][TFSI], and a lithium salt. In each system, the polymer-IL phase separation inhibited device operation at elevated temperatures. For the PEO/IL electrolyte, the thermally induced liquid-liquid phase separation was shown to decrease the ionic conductivity, thereby affecting the concentration of ions at the electrode. Additionally, an increasing charge transfer resistance associated with the phase separated polymer coating the porous electrode was shown to limit electrochemical activity significantly. For the PBzMA/IL electrolyte, the solid-liquid phase separation did not show a change in conductivity, but did cause a drastic increase in charge transfer resistance, effectively shutting off Li-ion battery operation at high temperatures. Such responsive mixtures provide a transformative approach to regulating electrochemical processes, which is necessary to achieve inherently safe operation in large format energy storage with EDLCs, supercapacitors and Li-ion batteries.

Electrochemical reduction of carbon dioxide. Final report

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

LaConti, A.B.; Molter, T.M.; Zagaja, J.A.

1986-05-01

Many researchers have studied the electrochemical reduction of carbon dioxide and related organic species to form concentrated liquid/gaseous products in laboratory-scale hardware. Hamilton Standard has developed a high pressure SPE electrolysis cell capable of reducing carbon dioxide streams to form pure, concentrated alcohols, carboxylic acids, and other hydrocarbons. The process is unique in that the byproducts of reaction include oxygen and, under some test conditions water. In addition, a relatively simple test system was designed and constructed permitting both batch and semibatch type electrochemical reduction studies. In this study, cathode materials were developed which 1) had a characteristic high hydrogenmore » overvoltage, and 2) possessed the intrinsic affinity for electrochemical reduction of the carbon dioxide species. In addition, suitable anode electrocatalyst materials were identified. Studies involving the electrochemical reduction of carbon dioxide required the ability to identify and quantify reaction products obtained during cell evaluation. Gas chromatographic techniques were developed along with the establishment of ion chromatographic methods permitting the analysis of organic reaction products. Hamilton Standard has evaluated electrochemical carbon dioxide reduction cells under a variety of test conditions.« less

Electrochemically induced annealing of stainless-steel surfaces.

PubMed

Burstein, G T; Hutchings, I M; Sasaki, K

2000-10-19

Modification of the surface properties of metals without affecting their bulk properties is of technological interest in demanding applications where surface stability and hardness are important. When austenitic stainless steel is heavily plastically deformed by grinding or rolling, a martensitic phase transformation occurs that causes significant changes in the bulk and surface mechanical properties of the alloy. This martensitic phase can also be generated in stainless-steel surfaces by cathodic charging, as a consequence of lattice strain generated by absorbed hydrogen. Heat treatment of the steel to temperatures of several hundred degrees can result in loss of the martensitic structure, but this alters the bulk properties of the alloy. Here we show that martensitic structures in stainless steel can be removed by appropriate electrochemical treatment in aqueous solutions at much lower temperature than conventional annealing treatments. This electrochemically induced annealing process allows the hardness of cold-worked stainless steels to be maintained, while eliminating the brittle martensitic phase from the surface. Using this approach, we are able to anneal the surface and near-surface regions of specimens that contain rolling-induced martensite throughout their bulk, as well as those containing surface martensite induced by grinding. Although the origin of the electrochemical annealing process still needs further clarification, we expect that this treatment will lead to further development in enhancing the surface properties of metals.

Synthesis and electrochemical properties of polyaniline nanofibers by interfacial polymerization.

PubMed

Manuel, James; Ahn, Jou-Hyeon; Kim, Dul-Sun; Ahn, Hyo-Jun; Kim, Ki-Won; Kim, Jae-Kwang; Jacobsson, Per

2012-04-01

Polyaniline nanofibers were prepared by interfacial polymerization with different organic solvents such as chloroform and carbon tetrachloride. Field emission scanning electron microscopy and transmission electron microscopy were used to study the morphological properties of polyaniline nanofibers. Chemical characterization was carried out using Fourier transform infrared spectroscopy, UV-Vis spectroscopy, and X-ray diffraction spectroscopy and surface area was measured using BET isotherm. Polyaniline nanofibers doped with lithium hexafluorophosphate were prepared and their electrochemical properties were evaluated.

Utilization of nanoparticle labels for signal amplification in ultrasensitive electrochemical affinity biosensors: a review.

PubMed

Ding, Liang; Bond, Alan M; Zhai, Jianping; Zhang, Jie

2013-10-03

Nanoparticles with desirable properties not exhibited by the bulk material can be readily synthesized because of rapid technological developments in the fields of materials science and nanotechnology. In particular their highly attractive electrochemical properties and electrocatalytic activity have facilitated achievement of the high level of signal amplification needed for the development of ultrasensitive electrochemical affinity biosensors for the detection of proteins and DNA. This review article explains the basic principles of nanoparticle based electrochemical biosensors, highlights the recent advances in the development of nanoparticle based signal amplification strategies, and provides a critical assessment of the likely drawbacks associated with each strategy. Finally, future perspectives for achieving advanced signal simplification in nanoparticles based biosensors are considered. Copyright © 2013 Elsevier B.V. All rights reserved.

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

Computational evaluation of sub-nanometer cluster activity of singly exposed copper atom with various coordinative environment in catalytic CO2 transformation

NASA Astrophysics Data System (ADS)

Shanmugam, Ramasamy; Thamaraichelvan, Arunachalam; Ganesan, Tharumeya Kuppusamy; Viswanathan, Balasubramanian

2017-02-01

Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO2 to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO2 to CO at an applied potential of -0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO2 to various value added chemicals.

Facile hydrothermal synthesis of one-dimensional nanostructured α-MnO2 for supercapacitors

NASA Astrophysics Data System (ADS)

Wei, Hongmei; Wang, Jinxing; Yang, Shengwei; Zhang, Yangyang; Li, Tengfei; Zhao, Shuoqing

2016-09-01

α-MnO2 recently becomes a promising candidate of electrode materials for high effective supercapacitors in which it possesses of unique structure of 2×2 tunnels that can provide more electrons and ions diffusion paths. In this work, different morphologies MnO2 with α-phase crystalline structure have been prepared via a one-step facile hydrothermal method by adding various reagents. Compositions, microstructures and morphologies of these as-synthesized materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and electrochemical properties of α-MnO2 electrodes were studied by the cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) in 1 M Na2SO4 aqueous solution. The specific capacitance of nanowires were 158 F g-1 while the specific capacitance of nanorods were 106 F g-1 at current density of 4 A g-1, and improved performance of the wire-like electrode material was probably ascribed to the larger specific surface area that can provide relatively more active sites for high capacity. Meanwhile, both the nanowires and nanorods of MnO2 presented fine cycle stability after continuous multiple charge/discharge times.

Urchin-like NiCo2O4 nanoneedles grown on mesocarbon microbeads with synergistic electrochemical properties as electrodes for symmetric supercapacitors.

PubMed

Zhang, Yu; Zhang, Yihe; Zhang, Deyang; Sun, Li

2017-07-25

Here, we report a facile method to fabricate NiCo 2 O 4 nanoneedles on mesocarbon microbeads (MCMB) and form a unique urchin-like core-shell structure. In this composite, the MCMB not only provided high conductivity to benefit effective electron transfer, but also offered abundant adsorption points to load the NiCo 2 O 4 nanoneedles. The aggregation of the NiCo 2 O 4 nanoneedles was therefore alleviated and each NiCo 2 O 4 grain was unfolded to gain easy access to the electrolyte for efficient ion transfer. When the NiCo 2 O 4 @MCMB composite was evaluated as an electrode material for supercapacitors, a synergistic effect was exerted with high specific capacitance (458 F g -1 at 1 A g -1 ) and large reversibility (116% capacitance retention after 3000 cycles), both of which were of great advantage over individual MCMB and NiCo 2 O 4 nanoneedles. The NiCo 2 O 4 @MCMB was also used to construct a symmetric supercapacitor, which showed enlarged voltage profiles and could light the LED device for a few minutes, further confirming its excellent electrochemical performance.

C@SiNW/TiO2 Core-Shell Nanoarrays with Sandwiched Carbon Passivation Layer as High Efficiency Photoelectrode for Water Splitting

PubMed Central

Devarapalli, Rami Reddy; Debgupta, Joyashish; Pillai, Vijayamohanan K.; Shelke, Manjusha V.

2014-01-01

One-dimensional heterostructure nanoarrays are efficiently promising as high performance electrodes for photo electrochemical (PEC) water splitting applications, wherein it is highly desirable for the electrode to have a broad light absorption, efficient charge separation and redox properties as well as defect free surface with high area suitable for fast interfacial charge transfer. We present highly active and unique photoelectrode for solar H2 production, consisting of silicon nanowires (SiNWs)/TiO2 core-shell structures. SiNWs are passivated to reduce defect sites and protected against oxidation in air or water by forming very thin carbon layer sandwiched between SiNW and TiO2 surfaces. This carbon layer decreases recombination rates and also enhances the interfacial charge transfer between the silicon and TiO2. A systematic investigation of the role of SiNW length and TiO2 thickness on photocurrent reveals enhanced photocurrent density up to 5.97 mA/cm2 at 1.0 V vs.NHE by using C@SiNW/TiO2 nanoarrays with photo electrochemical efficiency of 1.17%. PMID:24810865

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.

Nanostructured metal sulfides for energy storage

NASA Astrophysics Data System (ADS)

Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

2014-08-01

Advanced electrodes with a high energy density at high power are urgently needed for high-performance energy storage devices, including lithium-ion batteries (LIBs) and supercapacitors (SCs), to fulfil the requirements of future electrochemical power sources for applications such as in hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles. Metal sulfides with unique physical and chemical properties, as well as high specific capacity/capacitance, which are typically multiple times higher than that of the carbon/graphite-based materials, are currently studied as promising electrode materials. However, the implementation of these sulfide electrodes in practical applications is hindered by their inferior rate performance and cycling stability. Nanostructures offering the advantages of high surface-to-volume ratios, favourable transport properties, and high freedom for the volume change upon ion insertion/extraction and other reactions, present an opportunity to build next-generation LIBs and SCs. Thus, the development of novel concepts in material research to achieve new nanostructures paves the way for improved electrochemical performance. Herein, we summarize recent advances in nanostructured metal sulfides, such as iron sulfides, copper sulfides, cobalt sulfides, nickel sulfides, manganese sulfides, molybdenum sulfides, tin sulfides, with zero-, one-, two-, and three-dimensional morphologies for LIB and SC applications. In addition, the recently emerged concept of incorporating conductive matrices, especially graphene, with metal sulfide nanomaterials will also be highlighted. Finally, some remarks are made on the challenges and perspectives for the future development of metal sulfide-based LIB and SC devices.

Effect of electric impulse for improved energy generation in mediatorless dual chamber microbial fuel cell through electroevolution of Escherichia coli.

PubMed

Nandy, Arpita; Kumar, Vikash; Kundu, Patit P

2016-05-15

The main emphasis of this study is to understand the electroactive behavior of a microbe in microbial fuel cell (MFC) under specific selection pressure. This study explores potential of a non-electrogenic microbe for power production in a mediatorless MFC under the influence of a specific stress. Electric pulse of specific magnitude has been applied to Escherichia coli cells in a MFC and compared the results with unpulsed (control) MFC. Maximum power density of 187.77 mW/m(2) and 284.44 mW/m(2) for the control and experimental MFC has been observed at corresponding current density of 1444.44 mA/m(2) and 1777.77 mA/m(2). The results show improved performance for the pulsed (experimental) system, despite of initial downfall with respect to the control system. This suggests bacterial adaptation against electrical pulses which leads to evolution of an efficient electrogen. This observation is further confirmed by analyzing the results of Cyclic Voltammetry (CV), Scanning Electron Microscopy (SEM) Electrochemical Impedence Spectroscopy (EIS), enlightening different attributes like electrochemical property, bacterial morphology and impedance. The study is focused on development of a microbial fuel cell catalysed by E. coli, through triggering electroactive property in the microbe by exposing it to external stress. This study is unique in nature as it is mediatorless, economical and describes about a new method of natural bacterial evolution. Copyright © 2016 Elsevier B.V. All rights reserved.

25th anniversary article: semiconductor nanowires--synthesis, characterization, and applications.

PubMed

Dasgupta, Neil P; Sun, Jianwei; Liu, Chong; Brittman, Sarah; Andrews, Sean C; Lim, Jongwoo; Gao, Hanwei; Yan, Ruoxue; Yang, Peidong

2014-04-09

Semiconductor nanowires (NWs) have been studied extensively for over two decades for their novel electronic, photonic, thermal, electrochemical and mechanical properties. This comprehensive review article summarizes major advances in the synthesis, characterization, and application of these materials in the past decade. Developments in the understanding of the fundamental principles of "bottom-up" growth mechanisms are presented, with an emphasis on rational control of the morphology, stoichiometry, and crystal structure of the materials. This is followed by a discussion of the application of nanowires in i) electronic, ii) sensor, iii) photonic, iv) thermoelectric, v) photovoltaic, vi) photoelectrochemical, vii) battery, viii) mechanical, and ix) biological applications. Throughout the discussion, a detailed explanation of the unique properties associated with the one-dimensional nanowire geometry will be presented, and the benefits of these properties for the various applications will be highlighted. The review concludes with a brief perspective on future research directions, and remaining barriers which must be overcome for the successful commercial application of these technologies. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Modification of Holey Graphene for Energy Storage

NASA Technical Reports Server (NTRS)

Lin, Yi; Kim, Jae-Woo; Connell, John W.

2015-01-01

Porous graphene materials have recently drawn significant interest for energy storage applications due to the effective use of the graphitic surface area provided by the pores. Holey graphene is a type of porous graphene with pores in the form of physical through thickness holes. This type of porous graphene provides a unique morphology that allows for effective transport of molecular species through the graphene plane. Therefore, as we recently demonstrated, holey graphene could be advantageous in the preparation of electrodes in supercapacitors with high volumetric performance.1 We have developed methodologies to scalably prepare holey graphene materials with or without the use of catalysts (Figure 1).1,2 In this presentation, we will discuss the choice of synthetic strategies and experimental conditions on the morphology and physical properties of holey graphene (Figure 2) and the effect on their electrochemical properties. We will also present the results on the further modification of holey graphene to study their physical and chemical properties, especially with regard to the stability and chemical reactivity of carbons located around the edges of the holes.

Microstructural and optical properties of CdS nanoparticles synthesized by sol gel method

NASA Astrophysics Data System (ADS)

Mahdi, Hadeel Salih; Parveen, Azra; Agrawal, Shraddha; Azam, Ameer

2018-05-01

Semiconductor nanoparticles of CdS are of great interest for both fundamental research and industrial development due to their unique size-dependent optical and electronic properties and their exciting utilization in the fields of light-emitting diode, electro-chemical cells, laser, hydrogen producing catalyst, biological label. We present a scheme to measure the optical properties of CdS nanoparticles The peaks were indexed by powder-x software. The XRD pattern analysis showed that CdS composition was found to have hexagonal structure with well crystalline nature. the surface morphology and the composition of the samples were investigated by SEM (JEOL, japan). The image shows the presence of large spherical aggregates of smaller individual nanoparticles of various sizes for pure cds. to check the chemical composition of the material, energy dispersive X-ray (EDX) spectroscopic analysis was also performed which further confirmed the presence of cd and s ions in the matrix. The optical absorption spectra of CdS sample was recorded by uv-vis spectrophotometer in the range of 200 to 800 nm.

Enhanced antibacterial properties, biocompatibility, and corrosion resistance of degradable Mg-Nd-Zn-Zr alloy.

PubMed

Qin, Hui; Zhao, Yaochao; An, Zhiquan; Cheng, Mengqi; Wang, Qi; Cheng, Tao; Wang, Qiaojie; Wang, Jiaxing; Jiang, Yao; Zhang, Xianlong; Yuan, Guangyin

2015-06-01

Magnesium (Mg), a potential biodegradable material, has recently received increasing attention due to its unique antibacterial property. However, rapid corrosion in the physiological environment and potential toxicity limit clinical applications. In order to improve the corrosion resistance meanwhile not compromise the antibacterial activity, a novel Mg alloy, Mg-Nd-Zn-Zr (Hereafter, denoted as JDBM), is fabricated by alloying with neodymium (Nd), zinc (Zn), zirconium (Zr). pH value, Mg ion concentration, corrosion rate and electrochemical test show that the corrosion resistance of JDBM is enhanced. A systematic investigation of the in vitro and in vivo antibacterial capability of JDBM is performed. The results of microbiological counting, CLSM, SEM in vitro, and microbiological cultures, histopathology in vivo consistently show JDBM enhanced the antibacterial activity. In addition, the significantly improved cytocompatibility is observed from JDBM. The results suggest that JDBM effectively enhances the corrosion resistance, biocompatibility and antimicrobial properties of Mg by alloying with the proper amount of Zn, Zr and Nd. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrochemical Properties of LaNi(sub 5-x)Ge(sub x) Alloys in Ni-MH Batteries

NASA Technical Reports Server (NTRS)

Bowman, R. C., Jr.; Witham, C.

1997-01-01

Electrochemical studies were performed on LaNi(sub 5-x)Ge(sub x) metal hydride alloys with 0 <= x <= 0.5. We carried out single-electrode studies to understand the effects of the Ge substituent on the hydrogen absorption characteristics, the electrochemical capacity, and the electrochemical kinetics of hydrogen absorption and desorption.

Novel Nanofiber-based Membrane Separators for Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Yanilmaz, Meltem

Lithium-ion batteries have been widely used in electronic devices including mobile phones, laptop computers, and cameras due to their high specific energy, high energy density, long cycling lifetime, and low self-discharge rate. Nowadays, lithium-ion batteries are finding new applications in electric/hybrid vehicles and energy storage for smart grids. To be used in these new applications, novel battery components are needed so that lithiumion batteries with higher cell performance, better safety, and lower cost can be developed. A separator is an important component to obtain safe batteries and its primary function is to prevent electronic contact between electrodes while regulating cell kinetics and ionic flow. Currently, microporous membranes are the most commonly used separator type and they have good mechanical properties and chemical stability. However, their wettability and thermal stabilities are not sufficient for applications that require high operating temperature and high performance. Due to the superior properties such as large specific surface area, small pore size and high porosity, electrospun nanofiber membranes can be good separator candidate for highperformance lithium-ion batteries. In this work, we focus our research on fabricating nanofiber-based membranes to design new high-performance separators with good thermal stability, as well as superior electrochemical performance compared to microporous polyolefin membranes. To combine the good mechanical strength of PP nonwovens with the excellent electrochemical properties of SiO2/polyvinylidene fluoride (PVDF) composite nanofibers, SiO 2/PVDF composite nanofiber-coated PP nonwoven membranes were prepared. It was found that the addition of SiO2 nanoparticles played an important role in improving the overall performance of these nanofiber-coated nonwoven membranes. Although ceramic/polymer composites can be prepared by encapsulating ceramic particles directly into polymer nanofibers, the performance of the resultant composite membranes is restricted because these nanoparticles are not exposed to liquid electrolytes and have limited effect on improving the cell performance. Hence, we introduced new nanoparticle-on-nanofiber hybrid membrane separators by combining electrospraying with electrospinning techniques. Electrochemical properties were enhanced due to the increased surface area caused by the unique hybrid structure of SiO2 nanoparticles and PVDF nanofibers. To design a high-performance separator with enhanced mechanical properties and good thermal stability, electrospun SiO2/nylon 6,6 nanofiber membranes were fabricated. It was found that SiO2/nylon 6,6 nanofiber membranes had superior thermal stability and mechanical strength. Electrospinning has serious drawbacks such as low spinning rate and high production cost. Centrifugal spinning is a fast, cost-effective and safe alternative to the electrospinning. SiO2/polyacrylonitrile (PAN) membranes were produced by using centrifugal spinning. Compared with commercial microporous polyolefin membranes, SiO2/PAN membranes had larger liquid electrolyte uptake, higher electrochemical oxidation limit, and lower interfacial resistance with lithium. SiO2/PAN membrane separators were assembled into lithium/lithium iron phosphate cells and these cells exhibited good cycling and C-rate performance.

The dopant type and amount governs the electrochemical performance of graphene platforms for the antioxidant activity quantification

NASA Astrophysics Data System (ADS)

Hui, Kai Hwee; Ambrosi, Adriano; Sofer, Zdeněk; Pumera, Martin; Bonanni, Alessandra

2015-05-01

Graphene doped with heteroatoms can show new or improved properties as compared to the original undoped material. It has been reported that the type of heteroatoms and the doping conditions can have a strong influence on the electronic and electrochemical properties of the resulting material. Here, we wish to compare the electrochemical behavior of two n-type and two p-type doped graphenes, namely boron-doped graphenes and nitrogen-doped graphenes containing different amounts of heteroatoms. We show that the boron-doped graphene containing a higher amount of dopants provides the best electroanalytical performance in terms of calibration sensitivity, selectivity and linearity of response for the detection of gallic acid normally used as the standard probe for the quantification of antioxidant activity of food and beverages. Our findings demonstrate that the type and amount of heteroatoms used for the doping have a profound influence on the electrochemical detection of gallic acid rather than the structural properties of the materials such as amounts of defects, oxygen functionalities and surface area. This finding has a profound influence on the application of doped graphenes in the field of analytical chemistry.Graphene doped with heteroatoms can show new or improved properties as compared to the original undoped material. It has been reported that the type of heteroatoms and the doping conditions can have a strong influence on the electronic and electrochemical properties of the resulting material. Here, we wish to compare the electrochemical behavior of two n-type and two p-type doped graphenes, namely boron-doped graphenes and nitrogen-doped graphenes containing different amounts of heteroatoms. We show that the boron-doped graphene containing a higher amount of dopants provides the best electroanalytical performance in terms of calibration sensitivity, selectivity and linearity of response for the detection of gallic acid normally used as the standard probe for the quantification of antioxidant activity of food and beverages. Our findings demonstrate that the type and amount of heteroatoms used for the doping have a profound influence on the electrochemical detection of gallic acid rather than the structural properties of the materials such as amounts of defects, oxygen functionalities and surface area. This finding has a profound influence on the application of doped graphenes in the field of analytical chemistry. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01045d

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, H.L.; Kramer, S.A.; Spears, M.A.

1995-04-04

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided. 17 figures.

Effect of uniaxial stress on the electrochemical properties of graphene with point defects

NASA Astrophysics Data System (ADS)

Szroeder, Paweł; Sagalianov, Igor Yu.; Radchenko, Taras M.; Tatarenko, Valentyn A.; Prylutskyy, Yuriy I.; Strupiński, Włodzimierz

2018-06-01

We report a calculational study of electron states and the resulting electrochemical properties of uniaxially strained graphene with point defects. For this study the reduction of ferricyanide to ferrocyanide serves as a benchmark electrochemical reaction. We find that the heterogeneous electron transfer activity of the perfect graphene electrode rises under uniaxial strain. However, evolution of the cathodic reaction rate depends on the direction of strain. For moderate lattice deformations, the zigzag strain improves electrochemical performance better than the armchair strain. Standard rate constant increases by 50% at the zigzag strain of 10%. Vacancies, covalently bonded moieties, charged adatoms and substitutional impurities in the zigzag strained graphene induce changes in the shape of the curve of the cathodic reaction rate. However, this changes do not translate into the electrocatalytic activity. Vacancies and covalently bonded moieties at concentration of 0.1% do not affect the electrochemical performance. Charged adatoms and substitutional impurities give a slight increase in the standard rate constant by, respectively, 2.2% and 3.4%.

Physicochemical properties of precursors of Al2O3-ZrO2 oxide ceramics prepared by electrochemical method

NASA Astrophysics Data System (ADS)

Petrova, E. V.; Dresvyannikov, A. F.; Ahmadi Daryakenari, M.; Khairullina, A. I.

2016-05-01

Scanning electron microscopy, X-ray, and thermal analysis are used to examine the structure and properties of dispersive systems based on aluminum and zirconium oxides prepared electrochemically. The effect the conditions of synthesis have on the structure and morphology of Al2O3-ZrO2 particles is studied. It is shown that the effect of an electric field on the reaction medium allows us to adjust the physicochemical properties and morphology.

Exploring the Parameters Controlling the Crystallinity-Conductivity Correlation of PFSA Ionomers

NASA Astrophysics Data System (ADS)

Kusoglu, Ahmet; Shi, Shouwen; Weber, Adam

Perfluorosulfonic-acid (PFSA) ionomers are the most commonly used solid-electrolyte in electrochemical energy devices because of their remarkable conductivity and chemical/mechanical stability, with the latter imparted by their semi-crystalline fluorocarbon backbone. PFSAs owe this unique combination of transport/stability functionalities to their phase-separated morphology of conductive hydrophilic ionic domains and the non-conductive hydrophobic backbone, which are connected via pendant chains. Thus, phase-separation is governed by fractions of backbone and ionic groups, which is controlled by the equivalent weight (EW). Therefore, EW, along with the pendant chain chemistry, directly impact the conductive vs non-conductive regions, and consequently the interrelation between transport and stability. Driven by the need to achieve higher conductivities without disrupting the crystallinity, various pendant-chain chemistries have been developed. In this talk, we will report the results of a systematic investigation on hydration, conductivity, mechanical properties and crystallinity of various types and EWs of PFSA ionomers to (i) develop a structure/property map, and (ii) identify the key parameters controlling morphology and properties. It will be discussed how the pendant-chain and backbone lengths affect the conductivity and crystallinity, respectively. Lastly, the data set will be analyzed to explore universal structure/property relationships for PFSAs.

Immobilization Techniques in the Fabrication of Nanomaterial-Based Electrochemical Biosensors: A Review

PubMed Central

Putzbach, William; Ronkainen, Niina J.

2013-01-01

The evolution of 1st to 3rd generation electrochemical biosensors reflects a simplification and enhancement of the transduction pathway. However, in recent years, modification of the transducer with nanomaterials has become increasingly studied and imparts many advantages. The sensitivity and overall performance of enzymatic biosensors has improved tremendously as a result of incorporating nanomaterials in their fabrication. Given the unique and favorable qualities of gold nanoparticles, graphene and carbon nanotubes as applied to electrochemical biosensors, a consolidated survey of the different methods of nanomaterial immobilization on transducer surfaces and enzyme immobilization on these species is beneficial and timely. This review encompasses modification of enzymatic biosensors with gold nanoparticles, carbon nanotubes, and graphene. PMID:23580051

Immobilization techniques in the fabrication of nanomaterial-based electrochemical biosensors: a review.

PubMed

Putzbach, William; Ronkainen, Niina J

2013-04-11

The evolution of 1st to 3rd generation electrochemical biosensors reflects a simplification and enhancement of the transduction pathway. However, in recent years, modification of the transducer with nanomaterials has become increasingly studied and imparts many advantages. The sensitivity and overall performance of enzymatic biosensors has improved tremendously as a result of incorporating nanomaterials in their fabrication. Given the unique and favorable qualities of gold nanoparticles, graphene and carbon nanotubes as applied to electrochemical biosensors, a consolidated survey of the different methods of nanomaterial immobilization on transducer surfaces and enzyme immobilization on these species is beneficial and timely. This review encompasses modification of enzymatic biosensors with gold nanoparticles, carbon nanotubes, and graphene.

Formation of Sn–M (M=Fe, Al, Ni) alloy nanoparticles by DC arc-discharge and their electrochemical properties as anodes for Li-ion batteries

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

Gao, Song; Huang, Hao, E-mail: huanghao@dlut.edu.cn; Wu, Aimin

2016-10-15

A direct current arc-discharge method was applied to prepare the Sn–M (M=Fe, Al, Ni) bi-alloy nanoparticles. Thermodynamic is introduced to analyze the energy circumstances for the formation of the nanoparticles during the physical condensation process. The electrochemical properties of as-prepared Sn–M alloy nanoparticles are systematically investigated as anodes of Li-ion batteries. Among them, Sn–Fe nanoparticles electrode exhibits high Coulomb efficiency (about 71.2%) in the initial charge/discharge (257.9 mA h g{sup −1}/366.6 mA h g{sup −1}) and optimal cycle stability (a specific reversible capacity of 240 mA h g{sup −1} maintained after 20 cycles) compared with others. Large differences in themore » electrochemical behaviors indicate that the chemical composition and microstructure of the nanoparticles determine the lithium-ion storage properties and the long-term cyclic stability during the charge/discharge process. - Graphical abstract: The growth mechanism and electrochemical performance of Sn-based alloy nanoparticles. - Highlights: • Thermodynamic analyses of oxides on Sn-M nanoparticles surface. • The relationship between chemical components and electrochemical responses. • Sn-Fe nanoparticles show excellent electrode performance.« less

Electrochemical Corrosion of Stainless Steel in Thiosulfate Solutions Relevant to Gold Leaching

NASA Astrophysics Data System (ADS)

Choudhary, Lokesh; Wang, Wei; Alfantazi, Akram

2016-01-01

This study aims to characterize the electrochemical corrosion behavior of stainless steel in the ammoniacal thiosulfate gold leaching solutions. Electrochemical corrosion response was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy, while the semi-conductive properties and the chemical composition of the surface film were characterized using Mott-Schottky analysis and X-ray photoelectron spectroscopy, respectively. The morphology of the corroded specimens was analyzed using scanning electron microscopy. The stainless steel 316L showed no signs of pitting in the ammoniacal thiosulfate solutions.

Interesting electrochemical properties of novel three-dimensional Ag3PO4 tetrapods as a new super capacitor electrode material

NASA Astrophysics Data System (ADS)

Li, Shouguang; Teng, Fei; Chen, Mindong; Li, Na; Hua, Xia; Wang, Kai; Li, Min

2014-05-01

The novel three-dimensional (3D) silver phosphate tetrapods (TA) are synthesized and employed as a super capacitor electrode material. The electrochemical properties are investigated by cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). It is interesting that compared with irregular silver phosphate particles (IA), TA shows a higher capacitance (250 vs. 160 F g-1), and a higher coulombic efficiency (80% vs. 74%), which is mainly ascribed to the 3D microstructure and its high conductivity. To the best of our knowledge, this is the first report on silver phosphate as a super capacitor material.

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.

Sol-Gel Electrolytes Incorporated by Lanthanide Luminescent Materials and Their Photophysical Properties

NASA Astrophysics Data System (ADS)

Yu, Chufang; Zhang, Zhengyang; Fu, Meizhen; Gao, Jinwei; Zheng, Yuhui

2017-10-01

A group of silica gel electrolytes with lanthanide luminescent hybrid materials were assembled and investigated. Photophysical studies showed that terbium and europium hybrids displayed characteristic green and red emissions within the electrolytes. The influence of different concentration of the lanthanide hybrids on the electrochemical behavior of a gelled electrolyte valve-regulated lead-acid battery were studied through cyclic voltammograms, electrochemical impedance spectroscopy, water holding experiments and mobility tests. The morphology and particle size were analyzed by scanning electron microscopy. The results proved that lanthanide (Tb3+/Eu3+) luminescent materials are effective additives which will significantly improve the electrochemical properties of lead-acid batteries.

Metal-Embedded Porous Graphitic Carbon Fibers Fabricated from Bamboo Sticks as a Novel Cathode for Lithium-Sulfur Batteries.

PubMed

Zhang, Xuqing; Zhong, Yu; Xia, Xinhui; Xia, Yang; Wang, Donghuang; Zhou, Cheng'ao; Tang, Wangjia; Wang, Xiuli; Wu, J B; Tu, Jiangping

2018-04-25

Lithium-sulfur batteries (LSBs) are deemed to be among the most prospective next-generation advanced high-energy batteries. Advanced cathode materials fabricated from biological carbon are becoming more popular due to their unique properties. Inspired by the fibrous structure of bamboo, herein we put forward a smart strategy to convert bamboo sticks for barbecue into uniform bamboo carbon fibers (BCF) via a simple hydrothermal treatment proceeded in alkaline solution. Then NiCl 2 is used to etch the fibers through a heat treatment to achieve Ni-embedded porous graphitic carbon fibers (PGCF/Ni) for LSBs. The designed PGCF/Ni/S electrode exhibits improved electrochemical performances including high initial capacity (1198 mAh g -1 at 0.2 C), prolonged cycling life (1030 mAh g -1 at 0.2 C after 200 cycles), and improved rate capability. The excellent properties are attributed to the synergistic effect of 3D porous graphitic carbon fibers with highly conductive Ni nanoparticles embedded.

Fabrication of hierarchical porous hollow carbon spheres with few-layer graphene framework and high electrochemical activity for supercapacitor

NASA Astrophysics Data System (ADS)

Chen, Jing; Hong, Min; Chen, Jiafu; Hu, Tianzhao; Xu, Qun

2018-06-01

Porous amorphous carbons with large number of defects and dangling bonds indicate great potential application in energy storage due to high specific surface area and strong adsorption properties, but poor conductivity and pore connection limit their practical application. Here few-layer graphene framework with high electrical conductivity is embedded and meanwhile hierarchical porous structure is constructed in amorphous hollow carbon spheres (HCSs) by catalysis of Fe clusters of angstrom scale, which are loaded in the interior of crosslinked polystyrene via a novel method. These unique HCSs effectively integrate the inherent properties from two-dimensional sp2-hybridized carbon, porous amorphous carbon, hierarchical pore structure and thin shell, leading to high specific capacitance up to 561 F g-1 at a current density of 0.5 A g-1 as an electrode of supercapacitor with excellent recyclability, which is much higher than those of other reported porous carbon materials up to present.

Fabrication of three-dimensionally interconnected nanoparticle superlattices and their lithium-ion storage properties

PubMed Central

Jiao, Yucong; Han, Dandan; Ding, Yi; Zhang, Xianfeng; Guo, Guannan; Hu, Jianhua; Yang, Dong; Dong, Angang

2015-01-01

Three-dimensional superlattices consisting of nanoparticles represent a new class of condensed materials with collective properties arising from coupling interactions between close-packed nanoparticles. Despite recent advances in self-assembly of nanoparticle superlattices, the constituent materials have been limited to those that are attainable as monodisperse nanoparticles. In addition, self-assembled nanoparticle superlattices are generally weakly coupled due to the surface-coating ligands. Here we report the fabrication of three-dimensionally interconnected nanoparticle superlattices with face-centered cubic symmetry without the presynthesis of the constituent nanoparticles. We show that mesoporous carbon frameworks derived from self-assembled supercrystals can be used as a robust matrix for the growth of nanoparticle superlattices with diverse compositions. The resulting interconnected nanoparticle superlattices embedded in a carbon matrix are particularly suitable for energy storage applications. We demonstrate this by incorporating tin oxide nanoparticle superlattices as anode materials for lithium-ion batteries, and the resulting electrochemical performance is attributable to their unique architectures. PMID:25739732

Study of electrochemical reduced graphene oxide and MnO2 heterostructure for supercapacitor application

NASA Astrophysics Data System (ADS)

Jana, S. K.; Rao, V. P.; Banerjee, S.

2013-02-01

In this paper we have shown enhanced supercapacitive property of electrochemically reduced graphene oxide (ERGO) and manganese dioxide (MnO2) based heterostructure over single MnO2 thin film grown by electrochemical deposition on indium tin oxide (ITO). ERGO improves the electrical conduction leading to decrease of the internal resistance of the heterostructure.

Facile synthesis of NiAl-layered double hydroxide/graphene hybrid with enhanced electrochemical properties for detection of dopamine

NASA Astrophysics Data System (ADS)

Li, Meixia; Zhu, Jun E.; Zhang, Lili; Chen, Xu; Zhang, Huimin; Zhang, Fazhi; Xu, Sailong; Evans, David G.

2011-10-01

Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine electrooxidation in comparison with the pristine NiAl-LDH modified electrode. Results of high-resolution transmission electron microscopy and Raman spectra provide convincing information on the nanostructure and composition underlying the enhancement. Our results of the NiAl-LDH/G modified electrodes with the enhanced electrochemical performance may allow designing a variety of promising hybrid sensors via a simple and feasible approach.Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine electrooxidation in comparison with the pristine NiAl-LDH modified electrode. Results of high-resolution transmission electron microscopy and Raman spectra provide convincing information on the nanostructure and composition underlying the enhancement. Our results of the NiAl-LDH/G modified electrodes with the enhanced electrochemical performance may allow designing a variety of promising hybrid sensors via a simple and feasible approach. Electronic supplementary information (ESI) available: Fig. S1 showing 2D fast Fourier transform (FFT) image of NiAl-LDH phase in NiAl-LDH/G composites, and Fig. S2 showing CV curve of the pristine G modified electrode. See DOI: 10.1039/c1nr10592b.

Nitrogen-Doped Three Dimensional Graphene for Electrochemical Sensing.

PubMed

Yan, Jing; Chen, Ruwen; Liang, Qionglin; Li, Jinghong

2015-07-01

The rational assembly and doping of graphene play an crucial role in the improvement of electrochemical performance for analytical applications. Covalent assembly of graphene into ordered hierarchical structure provides an interconnected three dimensional conductive network and large specific area beneficial to electrolyte transfer on the electrode surface. Chemical doping with heteroatom is a powerful tool to intrinsically modify the electronic properties of graphene due to the increased free charge-carrier densities. By incorporating covalent assembly and nitrogen doping strategy, a novel nitrogen doped three dimensional reduced graphene oxide nanostructure (3D-N-RGO) was developed with synergetic enhancement in electrochemical behaviors. The as prepared 3D-N-RGO was further applied for catechol detection by differential pulse voltammetry. It exhibits much higher electrocatalytic activity towards catechol with increased peak current and decreased potential difference between the oxidation and reduction peaks. Owing to the improved electro-chemical properties, the response of the electrochemical sensor varies linearly with the catechol concentrations ranging from 5 µM to 100 µM with a detection limit of 2 µM (S/N = 3). This work is promising to open new possibilities in the study of novel graphene nanostructure and promote its potential electrochemical applications.

Electrochemical analyses of redox-active iron minerals: a review of nonmediated and mediated approaches.

PubMed

Sander, Michael; Hofstetter, Thomas B; Gorski, Christopher A

2015-05-19

Redox-active minerals are ubiquitous in the environment and are involved in numerous electron transfer reactions that significantly affect biogeochemical processes and cycles as well as pollutant dynamics. As a consequence, research in different scientific disciplines is devoted to elucidating the redox properties and reactivities of minerals. This review focuses on the characterization of mineral redox properties using electrochemical approaches from an applied (bio)geochemical and environmental analytical chemistry perspective. Establishing redox equilibria between the minerals and working electrodes is a major challenge in electrochemical measurements, which we discuss in an overview of traditional electrochemical techniques. These issues can be overcome with mediated electrochemical analyses in which dissolved redox mediators are used to increase the rate of electron transfer and to facilitate redox equilibration between working electrodes and minerals in both amperometric and potentiometric measurements. Using experimental data on an iron-bearing clay mineral, we illustrate how mediated electrochemical analyses can be employed to derive important thermodynamic and kinetic data on electron transfer to and from structural iron. We summarize anticipated methodological advancements that will further contribute to advance an improved understanding of electron transfer to and from minerals in environmentally relevant redox processes.

Aluminum oxyhydroxide based separator/electrolyte and battery system, and a method making the same

DOEpatents

Gerald, II, Rex E.; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL

2011-03-08

The instant invention relates a solid-state electrochemical cell and a novel separator/electrolyte incorporated therein. A preferred embodiment of the invented electrochemical cell generally comprises a unique metal oxyhydroxide based (i.e. AlOOH) separator/electrolyte membrane sandwiched between a first electrode and a second electrode. A preferred novel separator/electrolyte comprises a nanoparticulate metal oxyhydroxide, preferably AlOOH and a salt which are mixed and then pressed together to form a monolithic metal oxyhydroxide-salt membrane.

Aluminum oxyhydroxide based separator/electrolyte and battery system, and a method of making the same

DOEpatents

Gerald, II; Rex, E [Brookfield, IL; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL

2011-02-15

The instant invention relates a solid-state electrochemical cell and a novel separator/electrolyte incorporated therein. The invented electrochemical cell generally comprising: a unique metal oxyhydroxide based (i.e. AlOOH) separator/electrolyte membrane sandwiched between a first electrode and a second electrode. The novel separator/electrolyte comprises a nanoparticulate metal oxyhydroxide, preferably AlOOH and a salt which are mixed and then pressed together to form a monolithic metal oxyhydroxide-salt membrane.

Some Topics in Applied Electrochemical Kinetics,

DTIC Science & Technology

1980-07-01

AD-A097 405- DEFENE RESEARCH ESTABLiSHMENT OTTAWA (6NTARID3 F/G 7/ 4 SOME TOPICS IN APP LIED ELECTROCHEMICAL K INETICS.(U) JUL go E J CASEY, J R...electroplating, for a trans- port masurement, for electropolishing ; or it may be a battery of cells for storage of electrical energy; ar it may be a cell for the...product, or some other. Sometimes, although not always, the UNCLASSIFIED 4 UNCLASSIFIED slopes of these different steps are unique and permit

Boron doped ZnO embedded into reduced graphene oxide for electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Alver, Ü.; Tanrıverdi, A.

2016-08-01

In this work, reduced graphene oxide/boron doped zinc oxide (RGO/ZnO:B) composites were fabricated by a hydrothermal process and their electrochemical properties were investigated as a function of dopant concentration. First, boron doped ZnO (ZnO:B) particles was fabricated with different boron concentrations (5, 10, 15 and 20 wt%) and then ZnO:B particles were embedded into RGO sheets. The physical properties of sensitized composites were characterized by XRD and SEM. Characterization indicated that the ZnO:B particles with plate-like structure in the composite were dispersed on graphene sheets. The electrochemical properties of the RGO/ZnO:B composite were investigated through cyclic voltammetry, galvanostatic charge/discharge measurements in a 6 M KOH electrolyte. Electrochemical measurements show that the specific capacitance values of RGO/ZnO:B electrodes increase with increasing boron concentration. RGO/ZnO:B composite electrodes (20 wt% B) display the specific capacitance as high as 230.50 F/g at 5 mV/s, which is almost five times higher than that of RGO/ZnO (52.71 F/g).

Synthesis and electrochemical properties of Na-rich Prussian blue analogues containing Mn, Fe, Co, and Fe for Na-ion batteries

NASA Astrophysics Data System (ADS)

Bie, Xiaofei; Kubota, Kei; Hosaka, Tomooki; Chihara, Kuniko; Komaba, Shinichi

2018-02-01

Electrochemical performance of Prussian blue analogues (PBAs) as positive electrode materials for non-aqueous Na-ion batteries is known to be highly dependent on their synthesis conditions according to the previous researches. Na-rich PBAs, NaxM[Fe(CN)6]·nH2O where M = Mn, Fe, Co, and Ni, are prepared via precipitation method under the same condition. The structure, chemical composition, morphology, valence of the transition metals, and electrochemical property of these samples are comparatively researched. The PBA with Mn shows large reversible capacity of 126 mAh g-1 in 2.0-4.2 V at a current density of 30 mA g-1 and the highest working voltage owning to high redox potential of Mn2+/3+ in MnN6 and Fe2+/3+ in FeC6. While, the PBA with Ni exhibits the best cyclability and rate performance though only 66 mAh g-1 is delivered. The significant differences in electrochemical behaviors of the PBAs originate from the various properties depending on different transition metals.

Pectin, Hemicellulose, or Lignin? Impact of the Biowaste Source on the Performance of Hard Carbons for Sodium-Ion Batteries.

PubMed

Dou, Xinwei; Hasa, Ivana; Hekmatfar, Maral; Diemant, Thomas; Behm, R Jürgen; Buchholz, Daniel; Passerini, Stefano

2017-06-22

Hard carbons are currently the most widely used negative electrode materials in Na-ion batteries. This is due to their promising electrochemical performance with capacities of 200-300 mAh g -1 and stable long-term cycling. However, an abundant and cheap carbon source is necessary in order to comply with the low-cost philosophy of Na-ion technology. Many biological or waste materials have been used to synthesize hard carbons but the impact of the precursors on the final properties of the anode material is not fully understood. In this study the impact of the biomass source on the structural and electrochemical properties of hard carbons is unraveled by using different, representative types of biomass as examples. The systematic structural and electrochemical investigation of hard carbons derived from different sources-namely corncobs, peanut shells, and waste apples, which are representative of hemicellulose-, lignin- and pectin-rich biomass, respectively-enables understanding and interlinking of the structural and electrochemical properties. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical Detection in Stacked Paper Networks.

PubMed

Liu, Xiyuan; Lillehoj, Peter B

2015-08-01

Paper-based electrochemical biosensors are a promising technology that enables rapid, quantitative measurements on an inexpensive platform. However, the control of liquids in paper networks is generally limited to a single sample delivery step. Here, we propose a simple method to automate the loading and delivery of liquid samples to sensing electrodes on paper networks by stacking multiple layers of paper. Using these stacked paper devices (SPDs), we demonstrate a unique strategy to fully immerse planar electrodes by aqueous liquids via capillary flow. Amperometric measurements of xanthine oxidase revealed that electrochemical sensors on four-layer SPDs generated detection signals up to 75% higher compared with those on single-layer paper devices. Furthermore, measurements could be performed with minimal user involvement and completed within 30 min. Due to its simplicity, enhanced automation, and capability for quantitative measurements, stacked paper electrochemical biosensors can be useful tools for point-of-care testing in resource-limited settings. © 2015 Society for Laboratory Automation and Screening.

Fabrication and Performance Study on Individual Zno Nanowires Based Bioelectrode

NASA Astrophysics Data System (ADS)

Zhao, Yanguang; Yan, Xiaoqin; Kang, Zhuo; Lin, Pei

2012-08-01

One-dimensional zinc oxide nanowires (ZnO NWs) have unique advantages for use in biosensors as follows: oxide stable surface, excellent biosafety, high specific surface area, high isoelectric point (IEP = 9.5). In this work, we have prepared a kind of electrochemical bioelectrode based on individual ZnO NWs. Here, ZnO NWs with high quality were successfully synthesized by CVD method, which were characterized by scanning electron microscopy, X-ray diffraction and photoluminescence. Then the Raman spectra and electrical characterization demonstrated the adsorption of uricase on ZnO wires. At last, a series of electrochemical measurements were carried out by using an electrochemical workstation with a conventional three-electrode system to obtain the cyclic voltammetry characteristics of the bioelectrodes. The excellent performance of the fabricated bioelectrode implies the potential application for single ZnO nanowire to construct electrochemical biosensor for the detection of uric acid.

Copper-Nitrogen-Doped Graphene Hybrid as an Electrochemical Sensing Platform for Distinguishing DNA Bases.

PubMed

Sun, Shu-Wen; Liu, Hai-Ling; Zhou, Yue; Wang, Feng-Bin; Xia, Xing-Hua

2017-10-17

An electrochemical sensor using ultralight and porous copper-nitrogen-doped graphene (CuNRGO) nanocomposite as the electrocatalyst has been constructed to simultaneously determine DNA bases such as guanine (G) and cytosine (C), adenine (A), and thymine (T). The nanocomposite is synthesized by thermally annealing an ice-templated structure of graphene oxide (GO) and Cu(phen) 2 . Because of the unique structure and the presence of Cu 2+ -N active sites, the CuNRGO exhibits outstanding electrocatalytic activity toward the oxidation of free DNA bases. After optimizing the experimental conditions, the CuNRGO-based electrochemical sensor shows good linear responses for the G, A, T, and C bases in the concentration ranges of 0.132-6.62 μM, 0.37-5.18 μM, 198.2-5551 μM, and 270.0-1575 μM, respectively. The results demonstrate that CuNRGO is a promising electrocatalyst for electrochemical sensing devices.

3D-Printed Graphene/Polylactic Acid Electrodes Promise High Sensitivity in Electroanalysis.

PubMed

Manzanares Palenzuela, C Lorena; Novotný, Filip; Krupička, Petr; Sofer, Zdeněk; Pumera, Martin

2018-05-01

Additive manufacturing provides a unique tool for prototyping structures toward electrochemical sensing, due to its ability to produce highly versatile, tailored-shaped devices in a low-cost and fast way with minimized waste. Here we present 3D-printed graphene electrodes for electrochemical sensing. Ring- and disc-shaped electrodes were 3D-printed with a Fused Deposition Modeling printer and characterized using cyclic voltammetry and scanning electron microscopy. Different redox probes K 3 Fe(CN) 6 :K 4 Fe(CN) 6 , FeCl 3 , ascorbic acid, Ru(NH 3 ) 6 Cl 3 , and ferrocene monocarboxylic acid) were used to assess the electrochemical performance of these devices. Finally, the electrochemical detection of picric acid and ascorbic acid was carried out as proof-of-concept analytes for sensing applications. Such customizable platforms represent promising alternatives to conventional electrodes for a wide range of sensing applications.

Crystal structure and electrochemical properties of rare earth non-stoichiometric AB5-type alloy as negative electrode material in Ni-MH battery

NASA Astrophysics Data System (ADS)

Zhang, Xinbo; Chai, Yujun; Yin, Wenya; Zhao, Minshou

2004-07-01

The La 0.85Mg xNi 4.5Co 0.35Al 0.15 (0.05⩽ x⩽0.35) system compounds have been prepared by arc melting method under Ar atmosphere. X-ray diffraction (XRD) analysis reveals that the as-prepared alloys have different lattice parameters and cell volumes. The electrochemical properties of these alloys have been studied through the charge-discharge recycle testing at different temperatures and discharge currents. It is found that the La 0.85Mg 0.25Ni 4.5Co 0.35Al 0.15 alloy electrode is capable of performing high-rate discharge. Moreover, it has very excellent electrochemical properties as negative electrode materials in Ni-MH battery at low temperature, even at -40°C.

High-performance Fuel Cell with Stretched Catalyst-Coated Membrane: One-step Formation of Cracked Electrode

PubMed Central

Kim, Sang Moon; Ahn, Chi-Yeong; Cho, Yong-Hun; Kim, Sungjun; Hwang, Wonchan; Jang, Segeun; Shin, Sungsoo; Lee, Gunhee; Sung, Yung-Eun; Choi, Mansoo

2016-01-01

We have achieved performance enhancement of polymer electrolyte membrane fuel cell (PEMFC) though crack generation on its electrodes. It is the first attempt to enhance the performance of PEMFC by using cracks which are generally considered as defects. The pre-defined, cracked electrode was generated by stretching a catalyst-coated Nafion membrane. With the strain-stress property of the membrane that is unique in the aspect of plastic deformation, membrane electrolyte assembly (MEA) was successfully incorporated into the fuel cell. Cracked electrodes with the variation of strain were investigated and electrochemically evaluated. Remarkably, mechanical stretching of catalyst-coated Nafion membrane led to a decrease in membrane resistance and an improvement in mass transport, which resulted in enhanced device performance. PMID:27210793

Metal-containing and related polymers for biomedical applications.

PubMed

Yan, Yi; Zhang, Jiuyang; Ren, Lixia; Tang, Chuanbing

2016-10-07

A survey of the most recent progress in the biomedical applications of metal-containing polymers is given. Due to the unique optical, electrochemical, and magnetic properties, at least 30 different metal elements, most of them transition metals, are introduced into polymeric frameworks for interactions with biology-relevant substrates via various means. Inspired by the advance of metal-containing small molecular drugs and promoted by the great progress in polymer chemistry, metal-containing polymers have gained momentum during recent decades. According to their different applications, this review summarizes the following biomedical applications: (1) metal-containing polymers as drug delivery vehicles; (2) metal-containing polymeric drugs and biocides, including antimicrobial and antiviral agents, anticancer drugs, photodynamic therapy agents, radiotherapy agents and biocides; (3) metal-containing polymers as biosensors, and (4) metal-containing polymers in bioimaging.

In situ synthesis of TiO2(B) nanotube/nanoparticle composite anode materials for lithium ion batteries.

PubMed

Liu, Xiang; Sun, Qian; Ng, Alan M C; Djurišić, Aleksandra B; Xie, Maohai; Liao, Changzhong; Shih, Kaimin; Vranješ, Mila; Nedeljković, Jovan M; Deng, Zhaofeng

2015-10-23

Titania nanotubes were prepared by a simple hydrothermal route. Their electrochemical performance has been examined in detail and compared to TiO2(B) nanoparticles, TiO2 anatase and P25 titania nanoparticles. The cycling and rate performance of TiO2 nanotubes is superior to both types of nanoparticles, and it can be further improved by an in situ titanium precursor treatment, which results in the formation of TiO2 nanoparticles on/between the nanotubes. The obtained specific capacity after 200 cycles at 0.2 A g(-1) charge/discharge rate remained above 130 mAh g(-1). The enhanced lithium storage properties of these samples can be attributed to their unique morphology and crystal structure.

Biomolecule-based nanomaterials and nanostructures.

PubMed

Willner, Itamar; Willner, Bilha

2010-10-13

Biomolecule-nanoparticle (or carbon nanotube) hybrid systems provide new materials that combine the unique optical, electronic, or catalytic properties of the nanoelements with the recognition or biocatalytic functions of biomolecules. This article summarizes recent applications of biomolecule-nanoparticle (or carbon nanotubes) hybrid systems for sensing, synthesis of nanostructures, and for the fabrication of nanoscale devices. The use of metallic nanoparticles for the electrical contacting of redox enzymes with electrodes, and as catalytic labels for the development of electrochemical biosensors is discussed. Similarly, biomolecule-quantum dot hybrid systems are implemented for optical biosensing, and for monitoring intracellular metabolic processes. Also, the self-assembly of biomolecule-metal nanoparticle hybrids into nanostructures and functional nanodevices is presented. The future perspectives of the field are addressed by discussing future challenges and highlighting different potential applications.

Peptide and protein-based nanotubes for nanobiotechnology.

PubMed

Petrov, Anna; Audette, Gerald F

2012-01-01

The development of biologically relevant nanosystems such as biomolecular probes and sensors requires systems that effectively interface specific biochemical environments with abiotic architectures. The most widely studied nanomaterial, carbon nanotubes, has proven challenging in their adaptation for biomedical applications despite their numerous advantageous physical and electrochemical properties. On the other hand, development of bionanosystems through adaptation of existing biological systems has several advantages including their adaptability through modern recombinant DNA strategies. Indeed, the use of peptides, proteins and protein assemblies as nanotubes, scaffolds, and nanowires has shown much promise as a bottom-up approach to the development of novel bionanosystems. We highlight several unique peptide and protein systems that generate protein nanotubes (PNTs) that are being explored for the development of biosensors, probes, bionanowires, and drug delivery systems. Copyright © 2012 Wiley Periodicals, Inc.

Electronic and Electrochemical Properties of Nitrogen Doped Carbon Nanotubes

DTIC Science & Technology

2006-10-31

will be investigated. The research results will evaluate the potentials of nitrogen-doped carbon nanotubes for development of cathodes, gas sensors ...DPA – diphenylanthracene CVD – chemical vapor deposition CNx – nitrogen-doped carbon CNT – carbon nanotube MWNT – multiwall carbon nanotube SEM...3 Summary Page The aim of the project was a study of effect of nitrogen doping on the electronic and electrochemical properties of CNT . During

Influence of implantation on the electrochemical properties of smooth and porous TiN coatings for stimulation electrodes

NASA Astrophysics Data System (ADS)

Meijs, S.; Sørensen, C.; Sørensen, S.; Rechendorff, K.; Fjorback, M.; Rijkhoff, N. J. M.

2016-04-01

Objective. To determine whether changes in electrochemical properties of porous titanium nitride (TiN) electrodes as a function of time after implantation are different from those of smooth TiN electrodes. Approach. Eight smooth and 8 porous TiN coated electrodes were implanted in 8 rats. Before implantation, voltage transients, cyclic voltammograms and impedance spectra were recorded in phosphate buffered saline (PBS). After implantation, these measurements were done weekly to investigate how smooth and porous electrodes were affected by implantation. Main results. The electrode capacitance of the porous TiN electrodes decreased more than the capacitance of the smooth electrodes due to acute implantation under fast measurement conditions (such as stimulation pulses). This indicates that protein adhesion presents a greater diffusion limitation for counter-ions for the porous than for the smooth electrodes. The changes in electrochemical properties during the implanted period were similar for smooth and porous TiN electrodes, indicating that cell adhesion poses a similar diffusion limitation for smooth and porous electrodes. Significance. This knowledge can be used to optimize the porous structure of the TiN film, so that the effect of protein adhesion on the electrochemical properties is diminished. Alternatively, an additional coating could be applied on the porous TiN that would prevent or minimize protein adhesion.

In situ monitoring magnetism and resistance of nanophase platinum upon electrochemical oxidation.

PubMed

Steyskal, Eva-Maria; Topolovec, Stefan; Landgraf, Stephan; Krenn, Heinz; Würschum, Roland

2013-01-01

Controlled tuning of material properties by external stimuli represents one of the major topics of current research in the field of functional materials. Electrochemically induced property tuning has recently emerged as a promising pathway in this direction making use of nanophase materials with a high fraction of electrode-electrolyte interfaces. The present letter reports on electrochemical property tuning of porous nanocrystalline Pt. Deeper insight into the underlying processes could be gained by means of a direct comparison of the charge-induced response of two different properties, namely electrical resistance and magnetic moment. For this purpose, four-point resistance measurements and SQUID magnetometry were performed under identical in situ electrochemical control focussing on the regime of electrooxidation. Fully reversible variations of the electrical resistance and the magnetic moment of 6% and 1% were observed upon the formation or dissolution of a subatomic chemisorbed oxygen surface layer, respectively. The increase of the resistance, which is directly correlated to the amount of deposited oxygen, is considered to be primarily caused by charge-carrier scattering processes at the metal-electrolyte interfaces. In comparison, the decrease of the magnetic moment upon positive charging appears to be governed by the electric field at the nanocrystallite-electrolyte interfaces due to spin-orbit coupling.

Electrochemical thermodynamic measurement system

DOEpatents

Reynier, Yvan [Meylan, FR; Yazami, Rachid [Los Angeles, CA; Fultz, Brent T [Pasadena, CA

2009-09-29

The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

The effect of grain size on aluminum anodes for Al-air batteries in alkaline electrolytes

NASA Astrophysics Data System (ADS)

Fan, Liang; Lu, Huimin

2015-06-01

Aluminum is an ideal material for metallic fuel cells. In this research, different grain sizes of aluminum anodes are prepared by equal channel angular pressing (ECAP) at room temperature. Microstructure of the anodes is examined by electron backscatter diffraction (EBSD) in scanning electron microscope (SEM). Hydrogen corrosion rates of the Al anodes in 4 mol L-1 NaOH are determined by hydrogen collection method. The electrochemical properties of the aluminum anodes are investigated in the same electrolyte using electrochemical impedance spectroscopy (EIS) and polarization curves. Battery performance is also tested by constant current discharge at different current densities. Results confirm that the electrochemical properties of the aluminum anodes are related to grain size. Finer grain size anode restrains hydrogen evolution, improves electrochemical activity and increases anodic utilization rate. The proposed method is shown to effectively improve the performance of Al-air batteries.

Synergetic effects of K + and Mg 2+ ion intercalation on the electrochemical and actuation properties of the two-dimensional Ti 3 C 2 MXene

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

Gao, Qiang; Come, Jeremy; Naguib, Michael

2017-01-01

Two-dimensional materials, such as MXenes, are attractive candidates for energy storage and electrochemical actuators due to their high volume changes upon ion intercalation. Of special interest for boosting energy storage is the intercalation of multivalent ions such as Mg 2+, which suffers from sluggish intercalation and transport kinetics due to its ion size. By combining traditional electrochemical characterization techniques with electrochemical dilatometry and contact resonance atomic force microscopy, the synergetic effects of the pre-intercalation of K +ions are demonstrated to improve the charge storage of multivalent ions, as well as tune the mechanical and actuation properties of the Ti 3Cmore » 2MXene. Our results have important implications for quantitatively understanding the charge storage processes in intercalation compounds and provide a new path for studying the mechanical evolution of energy storage materials.« less

Binder-induced surface structure evolution effects on Li-ion battery performance

NASA Astrophysics Data System (ADS)

Rezvani, S. J.; Pasqualini, M.; Witkowska, A.; Gunnella, R.; Birrozzi, A.; Minicucci, M.; Rajantie, H.; Copley, M.; Nobili, F.; Di Cicco, A.

2018-03-01

A comparative investigation on binder induced chemical and morphological evolution of Li4Ti5O12 electrodes was performed via X-ray photoemission spectroscopy, scanning electron microscopy, and electrochemical measurements. Composite electrodes were obtained using three different binders (PAA, PVdF, and CMC) with 80:10:10 ratio of active material:carbon:binder. The electrochemical performances of the electrodes, were found to be intimately correlated with the evolution of the microstructure of the electrodes, probed by XPS and SEM analysis. Our analysis shows that the surface chemistry, thickness of the passivation layers and the morphology of the electrodes are strongly dependent on the type of binders that significantly influence the electrochemical properties of the electrodes. These results point to a key role played by binders in optimization of the battery performance and improve our understanding of the previously observed and unexplained electrochemical properties of these electrodes.

Fabrication of bismuth ferrite based hybrid nanostructures: Insight into a catalytic and sensing properties for the detection of biomolecules

NASA Astrophysics Data System (ADS)

Bharathkumar, S.; Sakar, M.; Balakumar, S.

2018-04-01

We made an attempt to construct a photocatalytic and biosensor platform by using bismuth ferrite (BiFeO3/BFO) particulates and fibers nanostructures towards the degradation of dye and electrochemical sensing of ascorbic acid. The crystal phase and morphology of the BFO nanostructures were confirmed using XRD and FESEM respectively. Further, their photocatalytic activity was tested under sunlight. The BFO fibers showed relatively an enhanced degradation property and an efficient electrochemical sensing property compared to the Particulates.

Acid-functionalized carbon nanofibers for high stability, thermoelectrical and electrochemical properties of nanofluids.

PubMed

Said, Zafar; Allagui, Anis; Abdelkareem, Mohammad Ali; Alawadhi, Hussain; Elsaid, Khaled

2018-06-15

Carbon-based nanofluids are viewed as promising thermal fluids for heat transfer applications. However, other properties, such as electrical conductivity and electrochemical behavior, are usually overlooked and rarely investigated despite their importance for the overall performance characterization of a given application. In this study, we synthesized PAN-based carbon nanofibers (CNF) by electrospinning, and characterized them using electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and thermogravimetric analysis. Thermoelectrical and electrochemical measurements were carried out on nanofluids. We found that, although CNF nanofluids exhibit good thermal and electrical properties with a negligible corrosive effect, the suspensions tend to sediment within a few days. However, acid treatment of CNF (F-CNF), which resulted in the shortening of the fibers and the appearance of surface-oxygenated species, made F-CNF-based nanofluids exhibit superior stability in water that extended for more than 90 days, with consistent and superior thermal and electrical properties. Copyright © 2018 Elsevier Inc. All rights reserved.

Effect of preparation methods on dispersion stability and electrochemical performance of graphene sheets

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

Chen, Li, E-mail: chenli1981@lut.cn; Li, Na; Zhang, Mingxia

Chemical exfoliation is one of the most important strategies for preparing graphene. The aggregation of graphene sheets severely prevents graphene from exhibiting excellent properties. However, there are no attempts to investigate the effect of preparation methods on the dispersity of graphene sheets. In this study, three chemical exfoliation methods, including Hummers method, modified Hummers method, and improved method, were used to prepare graphene sheets. The influence of preparation methods on the structure, dispersion stability in organic solvents, and electrochemical properties of graphene sheets were investigated. Fourier transform infrared microscopy, Raman spectra, transmission electron microscopy, and UV–vis spectrophotometry were employed tomore » analyze the structure of the as-prepared graphene sheets. The results showed that graphene prepared by improved method exhibits excellent dispersity and stability in organic solvents without any additional stabilizer or modifier, which is attributed to the completely exfoliation and regular structure. Moreover, cyclic voltammetric and electrochemical impedance spectroscopy measurements showed that graphene prepared by improved method exhibits superior electrochemical properties than that prepared by the other two methods. - Graphical abstract: Graphene oxides with different oxidation degree were obtained via three methods, and then graphene with different crystal structures were created by chemical reduction of exfoliated graphene oxides. - Highlights: • Graphene oxides with different oxidation degree were obtained via three oxidation methods. • The influence of oxidation methods on microstructure of graphene was investigated. • The effect of oxidation methods on dispersion stability of graphene was investigated. • The effect of oxidation methods on electrochemical properties of graphene was discussed.« less

Two new phases in the ternary RE-Ga-S systems with the unique interlinkage of GaS4 building units: synthesis, structure, and properties.

PubMed

Lin, Hua; Shen, Jin-Ni; Zhu, Wei-Wei; Liu, Yi; Wu, Xin-Tao; Zhu, Qi-Long; Wu, Li-Ming

2017-10-17

Two novel ternary rare-earth chalcogenides, Yb 6 Ga 4 S 15 and Lu 5 GaS 9 , have been prepared by solid-state reactions of an elemental mixture at high temperatures. Their structures were determined on the basis of single-crystal X-ray diffraction. Yb 6 Ga 4 S 15 crystallizes in the monoclinic space group C2/m (no.12) [a = 23.557(2) Å, b = 3.7664(4) Å, c = 12.466(1) Å, β = 90.915(9)°, V = 1105.9(2) Å 3 and Z = 2], whereas Lu 5 GaS 9 crystallizes in the triclinic space group P1[combining macron] (no.2) [a = 7.735(3) Å, b = 10.033(4) Å, c = 10.120(4) Å, α = 106.296(4)°, β = 100.178(5)°, γ = 101.946(3)°, V = 714.1(5) Å 3 and Z = 2]. Both the structures feature complicated three dimensional frameworks with the unique interlinkages of GaS 4 as basic building units. Significantly, photo-electrochemical measurements indicated that title compounds were photoresponsive under visible-light illumination. Furthermore, the UV-visible-near IR diffuse reflectance spectra, thermal stabilities, electronic structures, physical properties as well as a structure change trend of the ternary rare-earth/gallium/sulfur compounds have been evaluated.

Enhanced optical and electrochemical properties of polyaniline/cobalt oxide nano composite

NASA Astrophysics Data System (ADS)

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

2018-05-01

Polyaniline and its composites at different wt. % of Cobalt oxide nano (PDC1, PDC2 and PDC5) were prepared by in-situ chemical reaction method The optical property was carried out using UV-Vis. Absorption Spectroscopy. The electrochemical property like cyclic voltammetry and galvonostatic charging-discharging was carried out for PANI and PDC nanocomposite electrode materials. A specific capacitance of 212.08 F/g and 336.41 F/g with scan rates 100 and 200 mV/s at 0.4 A/g current density respectively. These results are suggesting PDC composite is a prominent candidate for supercapacitor properties applications.

Electrochemical capacitor

DOEpatents

Anderson, Marc A.; Liu, Kuo -Chuan; Mohr, Charles M.

1999-10-05

An inexpensive porous metal oxide material having high surface area, good conductivity and high specific capacitance is advantageously used in an electrochemical capacitor. The materials are formed in a sol-gel process which affords control over the properties of the resultant metal oxide materials.

The Electrochemical Properties of Sr(Ti,Fe)O 3-δ for Anodes in Solid Oxide Fuel Cells

DOE PAGES

Nenning, Andreas; Volgger, Lukas; Miller, Elizabeth; ...

2017-02-18

Reduction-stable mixed ionic and electronic conductors such as Sr(Ti,Fe)O 3-δ (STF) are promising materials for application in anodes of solid oxide fuel cells. The defect chemistry of STF and its properties as solid oxide fuel cell (SOFC) cathode have been studied thoroughly, while mechanistic investigations of its electrochemical properties as SOFC anode material are still scarce. In this study, thin film model electrodes of STF with 30% and 70% Fe content were investigated in H 2+H 2O atmosphere by electrochemical impedance spectroscopy. Lithographically patterned thin film Pt current collectors were applied on top or beneath the STF thin films tomore » compensate for the low electronic conductivity under reducing conditions. Oxygen exchange resistances, electronic and ionic conductivities and chemical capacitances were quantified and discussed in a defect chemical model. Increasing Fe content increases the electro-catalytic activity of the STF surface as well as the electronic and ionic conductivity. Current collectors on top also increase the electrochemical activity due to a highly active Pt-atmosphere-STF triple phase boundary. Furthermore, the electrochemical activity depends decisively on the H 2:H 2O mixing ratio and the polarization. Lastly, Fe 0 nanoparticles may evolve on the surface in hydrogen rich atmospheres and increase the hydrogen adsorption rate.« less

High electrochemical performances of hierarchical hydrangea macrophylla like NiCo{sub 2}O{sub 4} and NiCo{sub 2}S{sub 4} as anode materials for Li-ion batteries

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

Jin, Rencheng, E-mail: jinrc427@126.com; Liu, Gang; Liu, Chunping

2016-08-15

Graphical abstract: Mesoporous hydrangea macrophylla like NiCo{sub 2}O{sub 4} and NiCo{sub 2}S{sub 4} have been fabricated, which present excellent electrochemical performances as anode materials for Li-ion batteries. - Highlights: • Hierarchical NiCo{sub 2}O{sub 4} is successfully fabricated. • Hierarchical NiCo{sub 2}S{sub 4} is prepared via sulfide anion exchange. • The hierarchical NiCo{sub 2}O{sub 4} and NiCo{sub 2}S{sub 4} exhibit good electrochemical properties. - Abstract: In this work, hierarchical hydrangea macrophylla like NiCo{sub 2}O{sub 4} has been synthesized by solvothermal method followed by calcination treatment in air. By using Na{sub 2}S as sulfur source, the NiCo{sub 2}O{sub 4} is converted intomore » NiCo{sub 2}S{sub 4}. Such hierarchical NiCo{sub 2}O{sub 4} exhibits a high specific capacity and excellent cycling stability (928 mAh g{sup −1} at a current density of 100 mA g{sup −1} after 100 cycles). Even at high current density of 2000 mA g{sup −1}, the electrode still delivers a specific capacity of 371 mAh g{sup −1} after 50 cycles. When the NiCo{sub 2}S{sub 4} is used as anode materials for lithium-ion batteries, a high discharge capacity of 1204 mAh g{sup −1} can be achieved. Meanwhile, the NiCo{sub 2}S{sub 4} electrode displays good cycling stability and rate capability. The excellent electrochemical performances can be attributed to the unique porous structure, which can effectively reduce the diffusion length for lithium ions and electrons, and alleviate volume expansion during the charge-discharge processes.« less

Thermoelectric Properties of Cobalt Triantimonide (CoSb3) Prepared by an Electrochemical Technique

DTIC Science & Technology

2010-04-01

of the Co0.95Pd0.05Te0.05Sb2.95 material. Y. Lan et al . (5) suggested that the 9 mean free path for electrons in doped silicon (Si)-germanium...Sakamoto ARL-TR-5141 April 2010 Approved for public release; distribution unlimited...Adelphi, MD 20783-1197 ARL-TR-5141 April 2010 Thermoelectric Properties of Cobalt Triantimonide (CoSb3) Prepared by an Electrochemical

Synthesis, photophysical, and electrochemical properties of wide band gap tetraphenylsilane-carbazole derivatives: Effect of the substitution position and naphthalene side chain

NASA Astrophysics Data System (ADS)

Ho, Kar Wei; Ariffin, A.

2016-12-01

Four tetraphenylsilane-carbazole derivatives with wide bandgaps (3.38-3.55 eV) were synthesized. The effects of the substitution position and of the presence of naphthalene groups on the photophysical, electrochemical and thermal properties were investigated. The derivatives exhibited maximum absorption peaks ranging from 293 to 304 nm and maximum emission peaks ranging from 347 to 386 nm. Changing the carbazole substitution position on the tetraphenylsilane did not significantly change the photophysical and electrochemical properties. However, p-substituted compounds exhibited higher glass transition temperatures than m-substituted compounds. Naphthalene groups with bulky structures had extended the conjugation lengths that red-shifted both the absorption and emission spectra. The LUMO level was decreased, which reduced the optical bandgap and triplet energy level. However, the naphthalene groups significantly improved the thermal stability by increasing the glass transition temperature of the compounds.

The fabrication and electrochemical properties of electrospun nanofibers of a multiwalled carbon nanotube grafted by chitosan

NASA Astrophysics Data System (ADS)

Feng, Wei; Wu, Zigang; Li, Yu; Feng, Yiyu; Yuan, Xiaoyan

2008-03-01

Multiwalled carbon nanotubes (MWCNTs) were grafted by chitosan (CS); the product could disperse well in poly(vinyl alcohol) (PVA) aqueous solution with 2% (v/v) acetic acid solution. Because this product has potential in several biological fields, it was electrospun so as to enlarge the surface area. Raman spectra indicated that the electrospinning process did not severely alter the electron hybridization of carbon atoms within the nanotube framework. Moreover and interestingly, these nanofibers showed a novel sheath-core structure; the outer and inner diameters of these sheath-core nanofibers were about 200 nm and 100 nm, respectively. These nanofibers' electrochemical properties were characterized by detection of hydrogen peroxide and voltammetric responses of potassium ferricyanide. The electrospun fibers' web displayed faster electron transfer kinetics and better electrochemical properties than its cast film, which justified further applications in biological areas.

Formation of Onion-Like NiCo2 S4 Particles via Sequential Ion-Exchange for Hybrid Supercapacitors.

PubMed

Guan, Bu Yuan; Yu, Le; Wang, Xiao; Song, Shuyan; Lou, Xiong Wen David

2017-02-01

Onion-like NiCo 2 S 4 particles with unique hollow structured shells are synthesized by a sequential ion-exchange strategy. With the structural and compositional advantages, these unique onion-like NiCo 2 S 4 particles exhibit enhanced electrochemical performance as an electrode material for hybrid supercapacitors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoporous gold-based microbial biosensor for direct determination of sulfide.

PubMed

Liu, Zhuang; Ma, Hanyue; Sun, Huihui; Gao, Rui; Liu, Honglei; Wang, Xia; Xu, Ping; Xun, Luying

2017-12-15

Environmental pollution caused by sulfide compounds has become a major problem for public health. Hence, there is an urgent need to explore a sensitive, selective, and simple sulfide detection method for environmental monitoring and protection. Here, a novel microbial biosensor was developed using recombinant Escherichia coli BL21 (E. coli BL21) expressing sulfide:quinone oxidoreductase (SQR) for sulfide detection. As an important enzyme involved in the initial step of sulfide metabolism, SQR oxidizes sulfides to polysulfides and transfers electrons to the electron transport chain. Nanoporous gold (NPG) with its unique properties was selected for recombinant E. coli BL21 cells immobilization, and then glassy carbon electrode (GCE) was modified by the resulting E. coli/NPG biocomposites to construct an E. coli/NPG/GCE bioelectrode. Due to the catalytic oxidation properties of NPG for sulfide, the electrochemical reaction of the E. coli/NPG/GCE bioelectrode is attributed to the co-catalysis of SQR and NPG. For sulfide detection, the E. coli/NPG/GCE bioelectrode showed a good linear response ranging from 50μM to 5mM, with a high sensitivity of 18.35μAmM -1 cm -2 and a low detection limit of 2.55μM. The anti-interference ability of the E. coli/NPG/GCE bioelectrode is better than that of enzyme-based inhibitive biosensors. Further, the E. coli/NPG/GCE bioelectrode was successfully applied to the detection of sulfide in wastewater. These unique properties potentially make the E. coli/NPG/GCE bioelectrode an excellent choice for reliable sulfide detection. Copyright © 2017 Elsevier B.V. All rights reserved.

Recent advancements in nanoelectrodes and nanopipettes used in combined scanning electrochemical microscopy techniques.

PubMed

Kranz, Christine

2014-01-21

In recent years, major developments in scanning electrochemical microscopy (SECM) have significantly broadened the application range of this electroanalytical technique from high-resolution electrochemical imaging via nanoscale probes to large scale mapping using arrays of microelectrodes. A major driving force in advancing the SECM methodology is based on developing more sophisticated probes beyond conventional micro-disc electrodes usually based on noble metals or carbon microwires. This critical review focuses on the design and development of advanced electrochemical probes particularly enabling combinations of SECM with other analytical measurement techniques to provide information beyond exclusively measuring electrochemical sample properties. Consequently, this critical review will focus on recent progress and new developments towards multifunctional imaging.

Difluoro-and Trifluoromethylation of Electron-Deficient Alkenes in an Electrochemical Microreactor.

PubMed

Arai, Kenta; Watts, Kevin; Wirth, Thomas

2014-02-01

Electrochemical microreactors, which have electrodes integrated into the flow path, can afford rapid and efficient electrochemical reactions without redox reagents due to the intrinsic properties of short diffusion distances. Taking advantage of electrochemical microreactors, Kolbe electrolysis of di-and trifluoroacetic acid in the presence of various electron-deficient alkenes was performed under constant current at continuous flow at room temperature. As a result, di-and trifluoromethylated compounds were effectively produced in either equal or higher yields than identical reactions under batch conditions previously reported by Uneyamas group. The strategy of using electrochemical microreactor technology is useful for an effective fluoromethylation of alkenes based on Kolbe electrolysis in significantly shortened reaction times.

In-situ synthesized ZnFe2O4 firmly anchored to the surface of MWCNTs as a long-life anode material with high lithium storage performance

NASA Astrophysics Data System (ADS)

Yang, Tianbo; Zhang, Wanxi; Li, Linlin; Jin, Bo; Jin, Enmei; Jeong, Sangmoon; Jiang, Qing

2017-12-01

Because of two different metal cations in the crystal structures, binary transition metal oxides possess a lot of unique properties. ZnFe2O4 emerges from these transition metal oxides on account of its high theoretical capacity (1072 mAh g-1). One-dimensional multi-walled carbon nanotubes (MWCNTs) would be a desirable conductive additive for ZnFe2O4, thereby improving the electrochemical performance of ZnFe2O4. In this work, we prepare ZnFe2O4/MWCNTs by solvothermal method with further heat-treatment. ZnFe2O4 nanoparticles are firmly anchored to the surface of MWCNTs. ZnFe2O4/MWCNTs nanocomposite displays high specific capacity (1278 mAh g-1 at a current density of 200 mA g-1 after 200 cycles, and 565 mAh g-1 at a current density of 1500 mA g-1 after 500 cycles), and good rate performance (367 mAh g-1 even at a current density of 6000 mAh g-1 after 80 cycles). The superior electrochemical performance may promote ZnFe2O4 to be a promising alternative anode in lithium-ion batteries.

Hydrothermal synthesis of MnO2/CNT nanocomposite with a CNT core/porous MnO2 sheath hierarchy architecture for supercapacitors.

PubMed

Xia, Hui; Wang, Yu; Lin, Jianyi; Lu, Li

2012-01-05

MnO2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy analyses reveal that birnessite-type MnO2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture is built with a highly porous layer consisting of interconnected MnO2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K0.2MnO2·0.33 H2O)/28 wt.% CNT has a large specific surface area of 237.8 m2/g. Electrochemical properties of the CNT, the pure MnO2, and the MnO2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The MnO2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport.

Hydrothermal synthesis of MnO2/CNT nanocomposite with a CNT core/porous MnO2 sheath hierarchy architecture for supercapacitors

PubMed Central

2012-01-01

MnO2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy analyses reveal that birnessite-type MnO2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture is built with a highly porous layer consisting of interconnected MnO2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K0.2MnO2·0.33 H2O)/28 wt.% CNT has a large specific surface area of 237.8 m2/g. Electrochemical properties of the CNT, the pure MnO2, and the MnO2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The MnO2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport. PMID:24576342

Hydrothermal synthesis of MnO2/CNT nanocomposite with a CNT core/porous MnO2 sheath hierarchy architecture for supercapacitors

NASA Astrophysics Data System (ADS)

Xia, Hui; Wang, Yu; Lin, Jianyi; Lu, Li

2012-01-01

MnO2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy analyses reveal that birnessite-type MnO2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture is built with a highly porous layer consisting of interconnected MnO2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K0.2MnO2·0.33 H2O)/28 wt.% CNT has a large specific surface area of 237.8 m2/g. Electrochemical properties of the CNT, the pure MnO2, and the MnO2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The MnO2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport.

Synthesis of Two-Dimensional Materials for Capacitive Energy Storage

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

Mendoza-Sánchez, Beatriz; Gogotsi, Yury

The unique properties and great variety of two-dimensional (2D) nanomaterials make them highly attractive for energy storage applications. Here, an insight into the progress made towards the application of 2D nanomaterials for capacitive energy storage is provided. Moreover, synthesis methods, and electrochemical performance of various classes of 2D nanomaterials, particularly based on graphene, transition metal oxides, dichalcogenides, and carbides, are presented. Some factors that directly influence capacitive performance are discussed throughout the text and include nanosheet composition, morphology and texture, electrode architecture, and device configuration. Recent progress in the fabrication of 2D-nanomaterials-based microsupercapacitors and flexible and free-standing supercapacitors is presented.more » The main electrode manufacturing techniques with emphasis on scalability and cost-effectiveness are discussed, and include laser scribing, printing, and roll-to-roll manufacture. Some various issues that prevent the use of the full energy-storage potential of 2D nanomaterials and how they have been tackled are discussed, and include nanosheet aggregation and the low electrical conductivity of some 2D nanomaterials. In particular, the design of hybrid and hierarchical 2D and 3D structures based on 2D nanomaterials is presented. Other challenges and opportunities are discussed and include: control of nanosheets size and thickness, chemical and electrochemical instability, and scale-up of electrode films.« less

Synthesis of Two-Dimensional Materials for Capacitive Energy Storage

DOE PAGES

Mendoza-Sánchez, Beatriz; Gogotsi, Yury

2016-06-02

The unique properties and great variety of two-dimensional (2D) nanomaterials make them highly attractive for energy storage applications. Here, an insight into the progress made towards the application of 2D nanomaterials for capacitive energy storage is provided. Moreover, synthesis methods, and electrochemical performance of various classes of 2D nanomaterials, particularly based on graphene, transition metal oxides, dichalcogenides, and carbides, are presented. Some factors that directly influence capacitive performance are discussed throughout the text and include nanosheet composition, morphology and texture, electrode architecture, and device configuration. Recent progress in the fabrication of 2D-nanomaterials-based microsupercapacitors and flexible and free-standing supercapacitors is presented.more » The main electrode manufacturing techniques with emphasis on scalability and cost-effectiveness are discussed, and include laser scribing, printing, and roll-to-roll manufacture. Some various issues that prevent the use of the full energy-storage potential of 2D nanomaterials and how they have been tackled are discussed, and include nanosheet aggregation and the low electrical conductivity of some 2D nanomaterials. In particular, the design of hybrid and hierarchical 2D and 3D structures based on 2D nanomaterials is presented. Other challenges and opportunities are discussed and include: control of nanosheets size and thickness, chemical and electrochemical instability, and scale-up of electrode films.« less

An overview of carbon materials for flexible electrochemical capacitors.

PubMed

He, Yongmin; Chen, Wanjun; Gao, Caitian; Zhou, Jinyuan; Li, Xiaodong; Xie, Erqing

2013-10-07

Under the background of the quick development of lightweight, flexible, and wearable electronic devices in our society, a flexible and highly efficient energy management strategy is needed for their counterpart energy-storage systems. Among them, flexible electrochemical capacitors (ECs) have been considered as one of the most promising candidates because of their significant advantages in power and energy densities, and unique properties of being flexible, lightweight, low-cost, and environmentally friendly compared with current energy storage devices. In a common EC, carbon materials play an irreplaceable and principal role in its energy-storage performance. Up till now, most progress towards flexible ECs technologies has mostly benefited from the continuous development of carbon materials. As a result, in view of the dual remarkable highlights of ECs and carbon materials, a summary of recent research progress on carbon-based flexible EC electrode materials is presented in this review, including carbon fiber (CF, consisting of carbon microfiber-CMF and carbon nanofiber-CNF) networks, carbon nanotube (CNT) and graphene coatings, CNT and/or graphene papers (or films), and freestanding three-dimensional (3D) flexible carbon-based macroscopic architectures. Furthermore, some promising carbon materials for great potential applications in flexible ECs are introduced. Finally, the trends and challenges in the development of carbon-based electrode materials for flexible ECs and their smart applications are analyzed.

Direct electrochemistry of hemoglobin immobilized in CuO nanowire bundles.

PubMed

Li, Yueming; Zhang, Qian; Li, Jinghong

2010-11-15

It is one of main challenges to find the suitable materials to enhance the direct electron transfer between the electrode and redox protein for direct electrochemistry field. Nano-structured metal oxides have attracted considerable interest because of unique properties, well biocompatibility, and good stability. In this paper, the copper oxide nanowire bundles (CuO NWBs) were prepared via a template route, and the bioelectrochemical performances of hemoglobin (Hb) on the CuO NWBs modified glass carbon electrodes (denoted as Hb-CuO NWBs/GC) were studied. TEM and XRD were used to characterize the morphology and structure of the as synthesized CuO NWBs. Fourier transform-infrared spectroscopy (FT-IR) proved that Hb in the CuO NWBs matrix could retain its native secondary structure. A pair of well-defined and quasi-reversible redox peaks at approximately -0.325 V (vs. Ag/AgCl saturated KCl) were shown in the cyclic voltammogram curve for the Hb-CuO NWBs/GC electrode, which indicated the direct electrochemical behavior. The Hb-CuO NWBs/GC electrode also displayed a good electrocatalytic activity toward the reduction of hydrogen peroxide. These results indicate that the CuO NWBs are good substrates for immobilization of biomolecules and might be promising in the fields of (bio) electrochemical analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

Simultaneous determination of ascorbic acid, dopamine and uric acid by a novel electrochemical sensor based on N2/Ar RF plasma assisted graphene nanosheets/graphene nanoribbons.

PubMed

Jothi, Lavanya; Neogi, Sudarsan; Jaganathan, Saravana Kumar; Nageswaran, Gomathi

2018-05-15

A novel nitrogen/argon (N 2 /Ar) radio frequency (RF) plasma functionalized graphene nanosheet/graphene nanoribbon (GS/GNR) hybrid material (N 2 /Ar/GS/GNR) was developed for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Various nitrogen mites introduced into GS/GNR hybrid structure was evidenced by a detailed microscopic, spectroscopic and surface area analysis. Owing to the unique structure and properties originating from the enhanced surface area, nitrogen functional groups and defects introduced on both the basal and edges, N 2 /Ar/GS/GNR/GCE showed high electrocatalytic activity for the electrochemical oxidations of AA, DA, and UA with the respective lowest detection limits of 5.3, 2.5 and 5.7 nM and peak-to-peak separation potential (ΔE P ) (vs Ag/AgCl) in DPV of 220, 152 and 372 mV for AA/DA, DA/UA and AA/UA respectively. Moreover, the selectivity, stability, repeatability and excellent performance in real time application of the fabricated N 2 /Ar/GS/GNR/GCE electrode suggests that it can be considered as a potential electrode material for simultaneous detection of AA, DA, and UA. Copyright © 2018 Elsevier B.V. All rights reserved.

Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

PubMed

Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

2016-02-05

As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Calendering effects on the physical and electrochemical properties of Li[Ni1/3Mn1/3Co1/3]O2 cathode

NASA Astrophysics Data System (ADS)

Zheng, Honghe; Tan, Li; Liu, Gao; Song, Xiangyun; Battaglia, Vincent S.

2012-06-01

Li[Ni1/3Mn1/3Co1/3]O2 cathode laminate containing 8% PVDF and 7% acetylene black is fabricated and calendered to different porosities. Calendering effects on the physical and electrochemical properties of the Li[Ni1/3Mn1/3Co1/3]O2 cathode are investigated. It is found that mechanical properties of the composite laminate strongly depend on the electrode porosity whereas the electronic conductivity is not significantly affected by calendering. Electrochemical performances including the specific capacity, the first coulombic efficiency, cycling performance and rate capability for the cathode at different porosities are compared. An optimized porosity of around 30-40% is identified. Electrochemical impedance spectroscopy (EIS) studies illustrate that calendering improves the electronic conductivity between active particles at relatively high porosities, but increases charge transfer resistance at electrode/electrolyte interface at relatively low porosities. An increase of activation energy of Li interfacial transfer for the electrode at 0% porosity indicates a relatively high barrier of activation at the electrode/electrolyte interface, which accounts for the poor rate capability of the electrode at extremely low porosity.

Nanomaterial-Based Electrochemical Immunosensors for Clinically Significant Biomarkers

PubMed Central

Ronkainen, Niina J.; Okon, Stanley L.

2014-01-01

Nanotechnology has played a crucial role in the development of biosensors over the past decade. The development, testing, optimization, and validation of new biosensors has become a highly interdisciplinary effort involving experts in chemistry, biology, physics, engineering, and medicine. The sensitivity, the specificity and the reproducibility of biosensors have improved tremendously as a result of incorporating nanomaterials in their design. In general, nanomaterials-based electrochemical immunosensors amplify the sensitivity by facilitating greater loading of the larger sensing surface with biorecognition molecules as well as improving the electrochemical properties of the transducer. The most common types of nanomaterials and their properties will be described. In addition, the utilization of nanomaterials in immunosensors for biomarker detection will be discussed since these biosensors have enormous potential for a myriad of clinical uses. Electrochemical immunosensors provide a specific and simple analytical alternative as evidenced by their brief analysis times, inexpensive instrumentation, lower assay cost as well as good portability and amenability to miniaturization. The role nanomaterials play in biosensors, their ability to improve detection capabilities in low concentration analytes yielding clinically useful data and their impact on other biosensor performance properties will be discussed. Finally, the most common types of electroanalytical detection methods will be briefly touched upon. PMID:28788700

Ohmic resistance in a multi-anode MxCs

EPA Pesticide Factsheets

A-3txf_sequence summary.xksx: Abundance of contigs or unique sequences for each biofilm samples from anodes in the MEC reactorHodon Waterloo final_fasta_working.docx: Raw sequences with their identification numbersRNA S1_MEC.docx: Representative sequences with their ID number and taxonomyThis dataset is associated with the following publication:Santodomingo, J., H. Ryu, B. Dhar, and H. Lee. Ohmic resistance affects microbial community and electrochemical kinetics in a multi-anode microbial electrochemical cell. JOURNAL OF POWER SOURCES. Elsevier Science Ltd, New York, NY, USA, 331: 315-321, (2016).

Note: A quartz cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope measurements.

PubMed

Xia, Zhigang; Wang, Jihao; Hou, Yubin; Lu, Qingyou

2014-09-01

In this paper, we provide and demonstrate a design of a unique cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope (ECSTM) measurements. The active metal Pt electrode can be protected from air contamination during the preparation process. The transparency of the cell allows the tip and bead to be aligned by direct observation. Based on this, a new and effective alignment method is introduced. The high-quality bead preparations through this new cell have been confirmed by the ECSTM images of Pt (111).

Simultaneously Coupled Mechanical-Electrochemical-Thermal Simulation of Lithium-Ion Cells

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

Zhang, C.; Santhanagopalan, S.; Sprague, M. A.

2016-07-28

Understanding the combined electrochemical-thermal and mechanical response of a system has a variety of applications, for example, structural failure from electrochemical fatigue and the potential induced changes of material properties. For lithium-ion batteries, there is an added concern over the safety of the system in the event of mechanical failure of the cell components. In this work, we present a generic multi-scale simultaneously coupled mechanical-electrochemical-thermal model to examine the interaction between mechanical failure and electrochemical-thermal responses. We treat the battery cell as a homogeneous material while locally we explicitly solve for the mechanical response of individual components using a homogenizationmore » model and the electrochemical-thermal responses using an electrochemical model for the battery. A benchmark problem is established to demonstrate the proposed modeling framework. The model shows the capability to capture the gradual evolution of cell electrochemical-thermal responses, and predicts the variation of those responses under different short-circuit conditions.« less

Simultaneously Coupled Mechanical-Electrochemical-Thermal Simulation of Lithium-Ion Cells: Preprint

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

Zhang, Chao; Santhanagopalan, Shriram; Sprague, Michael A.

2016-08-01

Understanding the combined electrochemical-thermal and mechanical response of a system has a variety of applications, for example, structural failure from electrochemical fatigue and the potential induced changes of material properties. For lithium-ion batteries, there is an added concern over the safety of the system in the event of mechanical failure of the cell components. In this work, we present a generic multi-scale simultaneously coupled mechanical-electrochemical-thermal model to examine the interaction between mechanical failure and electrochemical-thermal responses. We treat the battery cell as a homogeneous material while locally we explicitly solve for the mechanical response of individual components using a homogenizationmore » model and the electrochemical-thermal responses using an electrochemical model for the battery. A benchmark problem is established to demonstrate the proposed modeling framework. The model shows the capability to capture the gradual evolution of cell electrochemical-thermal responses, and predicts the variation of those responses under different short-circuit conditions.« less

Potential-sensing electrochemical atomic force microscopy for in operando analysis of water-splitting catalysts and interfaces

NASA Astrophysics Data System (ADS)

Nellist, Michael R.; Laskowski, Forrest A. L.; Qiu, Jingjing; Hajibabaei, Hamed; Sivula, Kevin; Hamann, Thomas W.; Boettcher, Shannon W.

2018-01-01

Heterogeneous electrochemical phenomena, such as (photo)electrochemical water splitting to generate hydrogen using semiconductors and/or electrocatalysts, are driven by the accumulated charge carriers and thus the interfacial electrochemical potential gradients that promote charge transfer. However, measurements of the "surface" electrochemical potential during operation are not generally possible using conventional electrochemical techniques, which measure/control the potential of a conducting electrode substrate. Here we show that the nanoscale conducting tip of an atomic force microscope cantilever can sense the surface electrochemical potential of electrocatalysts in operando. To demonstrate utility, we measure the potential-dependent and thickness-dependent electronic properties of cobalt (oxy)hydroxide phosphate (CoPi). We then show that CoPi, when deposited on illuminated haematite (α-Fe2O3) photoelectrodes, acts as both a hole collector and an oxygen evolution catalyst. We demonstrate the versatility of the technique by comparing surface potentials of CoPi-decorated planar and mesoporous haematite and discuss viability for broader application in the study of electrochemical phenomena.

Electrochemical and fluorescence properties of SnO2 thin films and its antibacterial activity

NASA Astrophysics Data System (ADS)

Henry, J.; Mohanraj, K.; Sivakumar, G.; Umamaheswari, S.

2015-05-01

Nanocrystalline SnO2 thin films were deposited by a simple and inexpensive sol-gel spin coating technique and the films were annealed at two different temperatures (350 °C and 450 °C). Structural, vibrational, optical and electrochemical properties of the films were analyzed using XRD, FTIR, UV-Visible, fluorescence and cyclic voltammetry techniques respectively and their results are discussed in detail. The antimicrobial properties of SnO2 thin films were investigated by agar agar method and the results confirm the antibacterial activity of SnO2 against Escherichia coli and Bacillus.

Synthesis of 2-Azulenyltetrathiafulvalenes by Palladium-Catalyzed Direct Arylation of 2-Chloroazulenes with Tetrathiafulvalene and Their Optical and Electrochemical Properties.

PubMed

Shoji, Taku; Araki, Takanori; Sugiyama, Shuhei; Ohta, Akira; Sekiguchi, Ryuta; Ito, Shunji; Okujima, Tetsuo; Toyota, Kozo

2017-02-03

Tetrathiafulvalene (TTF) derivatives with 2-azulenyl substituents 5-11 were prepared by the palladium-catalyzed direct arylation reaction of 2-chloroazulenes with TTF in good yield. Photophysical properties of these compounds were investigated by UV-vis spectroscopy and theoretical calculations. Redox behavior of the novel azulene-substituted TTFs was examined by using cyclic voltammetry and differential pulse voltammetry, which revealed their multistep electrochemical oxidation and/or reduction properties. Moreover, these TTF derivatives showed significant spectral change in the visible region under the redox conditions.

Improved electrochemical and thermal properties of nickel rich LiNi0.6Co0.2Mn0.2O2 cathode materials by SiO2 coating

NASA Astrophysics Data System (ADS)

Cho, Woosuk; Kim, Sang-Min; Song, Jun Ho; Yim, Taeeun; Woo, Sang-Gil; Lee, Ko-Woon; Kim, Jeom-Soo; Kim, Young-Jun

2015-05-01

A surface coating of SiO2 is applied to a Ni rich LiNi0.6Co0.2Mn0.2O2 cathode material in a bid to improve its electrochemical and thermal properties. A uniform coating is achieved through a wet process using nano-sized SiO2 powder, and though the coated electrode is found to exhibit a reduced rate capability, its cycle performance at a high temperature of 60 °C is greatly enhanced. The effect of this SiO2 coating is further investigated by electrochemical impedance spectroscopy, which confirms that it suppresses the growth of interfacial impedance during progressive cycles. The SiO2 coating also demonstrates good HF scavenging ability, producing a subsequent reduction in the degradation of the active core material. The thermal properties of LiNi0.6Co0.2Mn0.2O2 are also improved by the SiO2 coating due to a reduction in the direct contact between the electrode and electrolyte. On the basis of these results, SiO2 coating is considered a viable surface modification method for improving the electrochemical and thermal properties of LiNi0.6Co0.2Mn0.2O2.

Effect of Heat Treatment on Electrochemical Properties of Mg-9 wt.%Al-2.5 wt.%Pb Alloy in Sodium Chloride Solution

NASA Astrophysics Data System (ADS)

Wang, Linqian; Wang, Richu; Feng, Yan; Deng, Min; Wang, Naiguang

2017-12-01

Mg-Al-Pb alloy can serve as a good candidate for the anode material in seawater-activated batteries. The effect of solution and aging treatment on electrochemical properties of Mg-9 wt.%Al-2.5 wt.%Pb alloy in 3.5 wt.% NaCl solution was investigated through scanning electron microscopy and electrochemical tests. The results indicate that the discharge activity of Mg-9 wt.%Al-2.5 wt.%Pb alloy decreases after solution treatment, although its anodic efficiency increases slightly. In contrast, its discharge performance and anodic efficiency, which are crucial for the application of batteries, are both enhanced after aging at 200°C for 12 h.

Voltage assisted asymmetric nanoscale wear on ultra-smooth diamond like carbon thin films at high sliding speeds

PubMed Central

Rajauria, Sukumar; Schreck, Erhard; Marchon, Bruno

2016-01-01

The understanding of tribo- and electro-chemical phenomenons on the molecular level at a sliding interface is a field of growing interest. Fundamental chemical and physical insights of sliding surfaces are crucial for understanding wear at an interface, particularly for nano or micro scale devices operating at high sliding speeds. A complete investigation of the electrochemical effects on high sliding speed interfaces requires a precise monitoring of both the associated wear and surface chemical reactions at the interface. Here, we demonstrate that head-disk interface inside a commercial magnetic storage hard disk drive provides a unique system for such studies. The results obtained shows that the voltage assisted electrochemical wear lead to asymmetric wear on either side of sliding interface. PMID:27150446

Voltage assisted asymmetric nanoscale wear on ultra-smooth diamond like carbon thin films at high sliding speeds

NASA Astrophysics Data System (ADS)

Rajauria, Sukumar; Schreck, Erhard; Marchon, Bruno

2016-05-01

The understanding of tribo- and electro-chemical phenomenons on the molecular level at a sliding interface is a field of growing interest. Fundamental chemical and physical insights of sliding surfaces are crucial for understanding wear at an interface, particularly for nano or micro scale devices operating at high sliding speeds. A complete investigation of the electrochemical effects on high sliding speed interfaces requires a precise monitoring of both the associated wear and surface chemical reactions at the interface. Here, we demonstrate that head-disk interface inside a commercial magnetic storage hard disk drive provides a unique system for such studies. The results obtained shows that the voltage assisted electrochemical wear lead to asymmetric wear on either side of sliding interface.

Synthesis and Performance of Highly Stable Star-Shaped Polyaniline Electrochromic Materials with Triphenylamine Core

NASA Astrophysics Data System (ADS)

Xiong, Shanxin; Li, Shuaishuai; Zhang, Xiangkai; Wang, Ru; Zhang, Runlan; Wang, Xiaoqin; Wu, Bohua; Gong, Ming; Chu, Jia

2018-02-01

The molecular architecture of conducting polymers has a significant impact on their conjugated structure and electrochemical properties. We have investigated the influence of star-shaped structure on the electrochemical and electrochromic properties of polyaniline (PANI). Star-shaped PANI (SPANI) was prepared by copolymerization of aniline with triphenylamine (TPA) using an emulsion polymerization method. With addition of less than 4.0 mol.% TPA, the resulting SPANI exhibited good solubility in xylene with dodecylbenzenesulfonic acid (DBSA) as doping acid. The structure and thermal stability of the SPANI were characterized using Fourier-transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis, and the electrochemical behavior was analyzed by cyclic voltammetry (CV). The electrochromic properties of SPANI were tested using an electrochemical workstation combined with an ultraviolet-visible (UV-Vis) spectrometer. The results show that, with increasing TPA loading, the thermal stability of SPANI increased. With addition of 4.0 mol.% TPA, the weight loss of SPANI was 36.9% at 700°C, much lower than the value of 71.2% for PANI at the same temperature. The low oxidation potential and large enclosed area of the CV curves indicate that SPANI possesses higher electrochemical activity than PANI. Enhanced electrochromic properties including higher optical contrast and better electrochromic stability of SPANI were also obtained. SPANI with 1.6 mol.% TPA loading exhibited the highest optical contrast of 0.71, higher than the values of 0.58 for PANI, 0.66 for SPANI-0.4%, or 0.63 for SPANI-4.0%. Overdosing of TPA resulted in slow switching speed due to slow ion transport in short branched chains of star-shaped PANI electrochromic material. Long-term stability testing confirmed that all the SPANI-based devices exhibited better stability than the PANI-based device.

Recent advances on ionic liquid uses in separation techniques.

PubMed

Berthod, A; Ruiz-Ángel, M J; Carda-Broch, S

2018-07-20

The molten organic salts with melting point below 100°C, commonly called ionic liquids (ILs) have found numerous uses in separation sciences due to their exceptional properties as non molecular solvents, namely, a negligible vapor pressure, a high thermal stability, and unique solvating properties due to polarity and their ionic character of molten salts. Other properties, such as viscosity, boiling point, water solubility, and electrochemical window, are adjustable playing with which anion is associated with which cation. This review focuses on recent development of the uses of ILs in separation techniques actualizing our 2008 article (same authors, J. Chromatogr. A, 1184 (2008) 6-18) focusing on alkyl methylimidazolium salts. These developments include the use of ILs in nuclear waste reprocessing, highly thermally stable ILs that allowed for the introduction of polar gas chromatography capillary columns able to work at temperature never seen before (passing 300°C), the use of ILs in liquid chromatography and capillary electrophoresis, and the introduction of tailor-made ILs for mass spectrometry detection of trace anions at the few femtogram level. The recently introduced deep eutectic solvents are not exactly ILs, they are related enough so that their properties and uses in countercurrent chromatography are presented. Copyright © 2017 Elsevier B.V. All rights reserved.

A practical guide to using boron doped diamond in electrochemical research.

PubMed

Macpherson, Julie V

2015-02-07

Conducting, boron doped diamond (BDD), in addition to its superior material properties, offers several notable attributes to the electrochemist making it an intriguing material for electrochemical research. These include the widest solvent window of all electrode materials; low background and capacitive currents; reduced fouling compared to other electrodes and; the ability to withstand extreme potentials, corrosive and high temperature/pressure environments. However, BDD is not your typical electrode material, it is a semi-conductor doped degenerately with boron to present semi-metallic characteristics. Input from materials scientists, chemists and physicists has been required to aid understanding of how to work with this material from an electrochemical viewpoint and improve electrode quality. Importantly, depending on how the BDD has been grown and then subsequently treated, prior to electrochemical measurement, the resulting material properties can vary quite significantly from one electrode to the next. This likely explains the variability seen by different researchers working on the same experimental systems. The aim of this "protocols" article is not to provide a state-of-the-art review of diamond electrochemistry, suitable references are provided to the interested reader, but instead serves as a reference point for any researcher wishing to commence work with diamond electrodes and interpret electrochemical data. It provides information on how best to characterise the material properties of the electrode before use and outlines the interplay between boron dopant density, non-diamond-carbon content, grain morphology, surface chemistry and redox couple identity. All should ideally be considered when interpretating electrochemical data arising from the diamond electrode. This will aid the reader in making meaningful comparisons between data obtained by different researchers using different diamond electrodes. The guide also aims to help educate the researcher in choosing which form of BDD is best suited to their research application.

Core–shell PdPb@Pd aerogels with multiply-twinned intermetallic nanostructures: facile synthesis with accelerated gelation kinetics and their enhanced electrocatalytic properties

DOE PAGES

Zhu, Chengzhou; Shi, Qiurong; Fu, Shaofang; ...

2018-04-04

Delicately engineering well-defined noble metal aerogels with favorable structural and compositional features is of vital importance for wide applications. Here, we reported a one-pot and facile method for synthesizing core–shell PdPb@Pd hydrogels/aerogels with multiply-twinned grains and an ordered intermetallic phase using sodium hypophosphite as a multifunctional reducing agent. Due to the accelerated gelation kinetics induced by increased reaction temperature and the specific function of sodium hypophosphite, the formation of hydrogels can be completed within 4 h. As a result, owing to their unique porous structure and favorable geometric and electronic effects, the optimized PdPb@Pd aerogels exhibit enhanced electrochemical performance towardsmore » ethylene glycol oxidation with a mass activity of 5.8 times higher than Pd black.« less

Conjugated amplifying polymers for optical sensing applications.

PubMed

Rochat, Sébastien; Swager, Timothy M

2013-06-12

Thanks to their unique optical and electrochemical properties, conjugated polymers have attracted considerable attention over the last two decades and resulted in numerous technological innovations. In particular, their implementation in sensing schemes and devices was widely investigated and produced a multitude of sensory systems and transduction mechanisms. Conjugated polymers possess numerous attractive features that make them particularly suitable for a broad variety of sensing tasks. They display sensory signal amplification (compared to their small-molecule counterparts) and their structures can easily be tailored to adjust solubility, absorption/emission wavelengths, energy offsets for excited state electron transfer, and/or for use in solution or in the solid state. This versatility has made conjugated polymers a fluorescence sensory platform of choice in the recent years. In this review, we highlight a variety of conjugated polymer-based sensory mechanisms together with selected examples from the recent literature.

Nanomaterials as analytical tools for genosensors.

PubMed

Abu-Salah, Khalid M; Alrokyan, Salman A; Khan, Muhammad Naziruddin; Ansari, Anees Ahmad

2010-01-01

Nanomaterials are being increasingly used for the development of electrochemical DNA biosensors, due to the unique electrocatalytic properties found in nanoscale materials. They offer excellent prospects for interfacing biological recognition events with electronic signal transduction and for designing a new generation of bioelectronic devices exhibiting novel functions. In particular, nanomaterials such as noble metal nanoparticles (Au, Pt), carbon nanotubes (CNTs), magnetic nanoparticles, quantum dots and metal oxide nanoparticles have been actively investigated for their applications in DNA biosensors, which have become a new interdisciplinary frontier between biological detection and material science. In this article, we address some of the main advances in this field over the past few years, discussing the issues and challenges with the aim of stimulating a broader interest in developing nanomaterial-based biosensors and improving their applications in disease diagnosis and food safety examination.

Engineered Graphene Materials: Synthesis and Applications for Polymer Electrolyte Membrane Fuel Cells.

PubMed

He, Daping; Tang, Haolin; Kou, Zongkui; Pan, Mu; Sun, Xueliang; Zhang, Jiujun; Mu, Shichun

2017-05-01

Engineered graphene materials (EGMs) with unique structures and properties have been incorporated into various components of polymer electrolyte membrane fuel cells (PEMFCs) such as electrode, membrane, and bipolar plates to achieve enhanced performances in terms of electrical conductivity, mechanical durability, corrosion resistance, and electrochemical surface area. This research news article provides an overview of the recent development in EGMs and EGM-based PEMFCs with a focus on the effects of EGMs on PEMFC performance when they are incorporated into different components of PEMFCs. The challenges of EGMs for practical PEMFC applications in terms of production scale, stability, conductivity, and coupling capability with other materials are also discussed and the corresponding measures and future research trends to overcome such challenges are proposed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Core–shell PdPb@Pd aerogels with multiply-twinned intermetallic nanostructures: facile synthesis with accelerated gelation kinetics and their enhanced electrocatalytic properties

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

Zhu, Chengzhou; Shi, Qiurong; Fu, Shaofang

Delicately engineering well-defined noble metal aerogels with favorable structural and compositional features is of vital importance for wide applications. Here, we reported a one-pot and facile method for synthesizing core–shell PdPb@Pd hydrogels/aerogels with multiply-twinned grains and an ordered intermetallic phase using sodium hypophosphite as a multifunctional reducing agent. Due to the accelerated gelation kinetics induced by increased reaction temperature and the specific function of sodium hypophosphite, the formation of hydrogels can be completed within 4 h. As a result, owing to their unique porous structure and favorable geometric and electronic effects, the optimized PdPb@Pd aerogels exhibit enhanced electrochemical performance towardsmore » ethylene glycol oxidation with a mass activity of 5.8 times higher than Pd black.« less

Nanomaterials as Analytical Tools for Genosensors

PubMed Central

Abu-Salah, Khalid M.; Alrokyan, Salman A.; Khan, Muhammad Naziruddin; Ansari, Anees Ahmad

2010-01-01

Nanomaterials are being increasingly used for the development of electrochemical DNA biosensors, due to the unique electrocatalytic properties found in nanoscale materials. They offer excellent prospects for interfacing biological recognition events with electronic signal transduction and for designing a new generation of bioelectronic devices exhibiting novel functions. In particular, nanomaterials such as noble metal nanoparticles (Au, Pt), carbon nanotubes (CNTs), magnetic nanoparticles, quantum dots and metal oxide nanoparticles have been actively investigated for their applications in DNA biosensors, which have become a new interdisciplinary frontier between biological detection and material science. In this article, we address some of the main advances in this field over the past few years, discussing the issues and challenges with the aim of stimulating a broader interest in developing nanomaterial-based biosensors and improving their applications in disease diagnosis and food safety examination. PMID:22315580

Embroidered electrochemical sensors on gauze for rapid quantification of wound biomarkers.

PubMed

Liu, Xiyuan; Lillehoj, Peter B

2017-12-15

Electrochemical sensors are an attractive platform for analytical measurements due to their high sensitivity, portability and fast response time. These attributes also make electrochemical sensors well suited for wearable applications which require excellent flexibility and durability. Towards this end, we have developed a robust electrochemical sensor on gauze via a unique embroidery fabrication process for quantitative measurements of wound biomarkers. For proof of principle, this biosensor was used to detect uric acid, a biomarker for wound severity and healing, in simulated wound fluid which exhibits high specificity, good linearly from 0 to 800µM, and excellent reproducibility. Continuous sensing of uric acid was also performed using this biosensor which reveals that it can generate consistent and accurate measurements for up to 7h. Experiments to evaluate the robustness of the embroidered gauze sensor demonstrate that it offers excellent resilience against mechanical stress and deformation, making it a promising wearable platform for assessing and monitoring wound status in situ. Copyright © 2017 Elsevier B.V. All rights reserved.

2-Dimensional micro-network of boron-doped diamond film: fabrication and electrochemical sensing application.

PubMed

Luo, Daibing; Wu, Liangzhuan; Zhi, Jinfang

2010-09-21

By means of delicate and conventional methods based on photolithography and hot filament chemical vapor deposition (HFCVD) technology, a novel boron-doped diamond micro-network (BDDMN) film was fabricated, and this micro-structure showed excellent electrochemical sensing properties.

Free Energies of Formation Measurements on Solid-State Electrochemical Cells

ERIC Educational Resources Information Center

Rollino, J. A.; Aronson, S.

1972-01-01

A simple experiment is proposed that can provide the student with some insight into the chemical properties of solids. It also demonstrates the relationship between the Gibbs free energy of formation of an ionic solid and the emf of an electrochemical cell. (DF)

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

Highly Stretchable Fully-Printed CNT-Based Electrochemical Sensors and Biofuel Cells: Combining Intrinsic and Design-Induced Stretchability.

PubMed

Bandodkar, Amay J; Jeerapan, Itthipon; You, Jung-Min; Nuñez-Flores, Rogelio; Wang, Joseph

2016-01-13

We present the first example of an all-printed, inexpensive, highly stretchable CNT-based electrochemical sensor and biofuel cell array. The synergistic effect of utilizing specially tailored screen printable stretchable inks that combine the attractive electrical and mechanical properties of CNTs with the elastomeric properties of polyurethane as a binder along with a judiciously designed free-standing serpentine pattern enables the printed device to possess two degrees of stretchability. Owing to these synergistic design and nanomaterial-based ink effects, the device withstands extremely large levels of strains (up to 500% strain) with negligible effect on its structural integrity and performance. This represents the highest stretchability offered by a printed device reported to date. Extensive electrochemical characterization of the printed device reveal that repeated stretching, torsional twisting, and indenting stress has negligible impact on its electrochemical properties. The wide-range applicability of this platform to realize highly stretchable CNT-based electrochemical sensors and biofuel cells has been demonstrated by fabricating and characterizing potentiometric ammonium sensor, amperometric enzyme-based glucose sensor, enzymatic glucose biofuel cell, and self-powered biosensor. Highly stretchable printable multianalyte sensor, multifuel biofuel cell, or any combination thereof can thus be realized using the printed CNT array. Such combination of intrinsically stretchable printed nanomaterial-based electrodes and strain-enduring design patterns holds considerable promise for creating an attractive class of inexpensive multifunctional, highly stretchable printed devices that satisfy the requirements of diverse healthcare and energy fields wherein resilience toward extreme mechanical deformations is mandatory.

Impact of Backbone Tether Length and Structure on the Electrochemical Performance of Viologen Redox Active Polymers

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

Burgess, Mark; Chénard, Etienne; Hernández-Burgos, Kenneth

The design of chemically stable and electrochemically reversible redox active polymers (RAPs) is of great interest for energy storage technologies. Particularly, RAPs are new players for flow batteries relying on a size-exclusion based mechanism of electrolyte separation, but few studies have provided detailed molecular understanding of redox polymers in solution. Here, we use a systematic molecular design approach to investigate the impact of linker and redox-pendant electronic interactions on the performance of viologen RAPs. We used scanning electrochemical microscopy, cyclic voltammetry, bulk electrolysis, temperature-dependent absorbance, and spectroelectrochemistry to study the redox properties, charge transfer kinetics, and self-exchange of electrons throughmore » redox active dimers and their equivalent polymers. Stark contrast was observed between the electrochemical properties of viologen dimers and their corresponding polymers. Electron self-exchange kinetics in redox active dimers that only differ by their tether length and rigidity influences their charge transfer properties. Predictions from the Marcus Hush theory were consistent with observations in redox active dimers, but they failed to fully capture the behavior of macromolecular systems. For example, polymer bound viologen pendants, if too close in proximity, do not retain chemical reversibility. In contrast to polymer films, small modifications to the backbone structure decisively impact the bulk electrolysis of polymer solutions. This first comprehensive study highlights the careful balance between electronic interactions and backbone rigidity required to design RAPs with superior electrochemical performance.« less

The effect of crystal orientation on the aluminum anodes of the aluminum-air batteries in alkaline electrolytes

NASA Astrophysics Data System (ADS)

Fan, Liang; Lu, Huimin; Leng, Jing; Sun, Zegao; Chen, Chunbo

2015-12-01

Recently, aluminum-air (Al-air) batteries have received attention from researchers as an exciting option for safe and efficient batteries. The electrochemical performance of Aluminum anode remains an active area of investigation. In this paper, the electrochemical properties of polycrystalline Al, Al (001), (110) and (111) single crystals are investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 4 M NaOH and KOH. Hydrogen corrosion rates of the Al anodes are determined by hydrogen collection. Battery performance using the anodes is tested by constant current discharge at 10 mA cm-2. This is the first report showing that the electrochemical properties of Al are closely related to the crystallographic orientation in alkaline electrolytes. The (001) crystallographic plane has good corrosion resistance but (110) is more sensitive. Al (001) single crystals display higher anode efficiency and capacity density. Controlling the crystallographic orientation of the Al anode is another way to improve the performance of Al-air batteries in alkaline electrolytes.

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.

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.

Compacted carbon for electrochemical cells

DOEpatents

Greinke, Ronald Alfred; Lewis, Irwin Charles

1997-01-01

This invention provides compacted carbon that is useful in the electrode of an alkali metal/carbon electrochemical cell of improved capacity selected from the group consisting of: (a) coke having the following properties: (i) an x-ray density of at least 2.00 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 47%; and (b) graphite having the following properties: (i) an x-ray density of at least 2.20 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 25%. This invention also relates to an electrode for an alkali metal/carbon electrochemical cell comprising compacted carbon as described above and a binder. This invention further provides an alkali metal/carbon electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrolytically conductive salt and an alkali metal, and (c) a counterelectrode.

Compacted carbon for electrochemical cells

DOEpatents

Greinke, R.A.; Lewis, I.C.

1997-10-14

This invention provides compacted carbon that is useful in the electrode of an alkali metal/carbon electrochemical cell of improved capacity selected from the group consisting of: (a) coke having the following properties: (1) an x-ray density of at least 2.00 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 47%; and (b) graphite having the following properties: (1) an x-ray density of at least 2.20 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 25%. This invention also relates to an electrode for an alkali metal/carbon electrochemical cell comprising compacted carbon as described above and a binder. This invention further provides an alkali metal/carbon electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrolytically conductive salt and an alkali metal, and (c) a counter electrode. 10 figs.

Bio-functionalized graphene–graphene oxide nanocomposite based electrochemical immunosensing

PubMed Central

Sharma, Priyanka; Tuteja, Satish K.; Bhalla, Vijayender; Shekhawat, G.; Dravid, Vinayak P.; Suri, C.Raman

2014-01-01

We report a novel in-situ electrochemical synthesis approach for the formation of functionalized graphene–graphene oxide (fG–GO) nanocomposite on screen-printed electrodes (SPE). Electrochemically controlled nanocomposite film formation was studied by transmission electron microscopy (TEM) and Raman spectroscopy. Further insight into the nanocomposite has been accomplished by the Fourier transformed infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) spectroscopy. Configured as a highly responsive screen-printed immunosensor, the fG–GO nanocomposite on SPE exhibits electrical and chemical synergies of the nano-hybrid functional construct by combining good electronic properties of functionalized graphene (fG) and the facile chemical functionality of graphene oxide (GO) for compatible bio-interface development using specific anti-diuron antibody. The enhanced electrical properties of nanocomposite biofilm demonstrated a significant increase in electrochemical signal response in a competitive inhibition immunoassay format for diuron detection, promising its potential applicability for ultra-sensitive detection of range of target analytes. PMID:22884654

Electrochemistry and electron paramagnetic resonance spectroscopy of cytochrome c and its heme-disrupted analogs.

PubMed

Novak, David; Mojovic, Milos; Pavicevic, Aleksandra; Zatloukalova, Martina; Hernychova, Lenka; Bartosik, Martin; Vacek, Jan

2018-02-01

Cytochrome c (cyt c) is one of the most studied conjugated proteins due to its electron-transfer properties and ability to regulate the processes involved in homeostasis or apoptosis. Here we report an electrochemical strategy for investigating the electroactivity of cyt c and its analogs with a disrupted heme moiety, i.e. apocytochrome c (acyt c) and porphyrin cytochrome c (pcyt c). The electrochemical data are supplemented with low-temperature and spin-probe electron paramagnetic resonance (EPR) spectroscopy. The main contribution of this report is a complex evaluation of cyt c reduction and oxidation at the level of surface-localized amino acid residues and the heme moiety in a single electrochemical scan. The electrochemical pattern of cyt c is substantially different to both analogs acyt c and pcyt c, which could be applicable in further studies on the redox properties and structural stability of cytochromes and other hemeproteins. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochemically Controlled Ion-exchange Property of Carbon Nanotubes/Polypyrrole Nanocomposite in Various Electrolyte Solutions

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

Choi, Daiwon; Zhu, Chengzhou; Fu, Shaofang

2016-09-15

The electrochemically controlled ion-exchange properties of multi-wall carbon nanotube (MWNT)/electronically conductive polypyrrole (PPy) polymer composite in the various electrolyte solutions have been investigated. The ion-exchange behavior, rate and capacity of the electrochemically deposited polypyrrole with and without carbon nanotube (CNT) were compared and characterized using cyclic voltammetry (CV), chronoamperometry (CA), electrochemical quartz crystal microbalance (EQCM), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It has been found that the presence of carbon nanotube backbone resulted in improvement in ion-exchange rate, stability of polypyrrole, and higher anion loading capacity per PPy due to higher surface area, electronic conductivity, porous structuremore » of thin film, and thinner film thickness providing shorter diffusion path. Chronoamperometric studies show that electrically switched anion exchange could be completed more than 10 times faster than pure PPy thin film. The anion selectivity of CNT/PPy film is demonstrated using X-ray photoelectron spectroscopy (XPS).« less

Origin of electrochemical, structural and transport properties in non-aqueous zinc electrolytes

DOE PAGES

Han, Sang -Don; Rajput, Nav Nidhi; Qu, Xiaohui; ...

2016-01-14

Through coupled experimental analysis and computational techniques, we uncover the origin of anodic stability for a range of nonaqueous zinc electrolytes. By examination of electrochemical, structural, and transport properties of nonaqueous zinc electrolytes with varying concentrations, it is demonstrated that the acetonitrile Zn(TFSI) 2, acetonitrile Zn(CF 3SO 3) 2, and propylene carbonate Zn(TFSI) 2 electrolytes can not only support highly reversible Zn deposition behavior on a Zn metal anode (≥99% of Coulombic efficiency), but also provide high anodic stability (up to ~3.8 V). The predicted anodic stability from DFT calculations is well in accordance with experimental results, and elucidates thatmore » the solvents play an important role in anodic stability of most electrolytes. Molecular dynamics (MD) simulations were used to understand the solvation structure (e.g., ion solvation and ionic association) and its effect on dynamics and transport properties (e.g., diffusion coefficient and ionic conductivity) of the electrolytes. Lastly, the combination of these techniques provides unprecedented insight into the origin of the electrochemical, structural, and transport properties in nonaqueous zinc electrolytes« less

GO/PEDOT:PSS nanocomposites: effect of different dispersing agents on rheological, thermal, wettability and electrochemical properties

NASA Astrophysics Data System (ADS)

Giuri, Antonella; Masi, Sofia; Colella, Silvia; Listorti, Andrea; Rizzo, Aurora; Liscio, Andrea; Treossi, Emanuele; Palermo, Vincenzo; Gigli, Giuseppe; Mele, Claudio; Esposito Corcione, Carola

2017-04-01

In this work glucose (G), α-cyclodextrin (α-CD) and sodium salt of carboxymethyl cellulose (CMCNa) are used as dispersing agents for graphene oxide (GO), exploring the influence of both saccharide units and geometric/steric hindrance on the rheological, thermal, wettability and electrochemical properties of a GO/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) nanocomposite. By acting on the saccharide-based additives, we can modulate the rheological, thermal, and wettability properties of the GO/PEDOT:PSS nanocomposite. Firstly, the influence of all the additives on the rheological behaviour of GO and PEDOT:PSS was investigated separately in order to understand the effect of the dispersing agent on both the components of the ternary nanocomposite, individually. Subsequently, steady shear and dynamic frequency tests were conducted on all the nanocomposite solutions, characterized by thermal, wettability and morphological analysis. Finally, the electrochemical properties of the GO/PEDOT composites with different dispersing agents for supercapacitors were investigated using cyclic voltammetry (CV). The CV results revealed that GO/PEDOT with glucose exhibited the highest specific capacitance among the systems investigated.

Effect of carbonization temperature on the physical and electrochemical properties of supercapacitor electrode from fibers of oil palm empty fruit bunches

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

Ishak, M. M.; Deraman, M., E-mail: madra@ukm.my; Talib, I. A.

Self-adhesive carbon grains (SACG) was prepared from fibers of oil palm empty fruit bunches. The SACG green monoliths were carbonized in N{sub 2} environment at 400, 500, 600 and 700°C to produce carbon monoliths labeled as CM1, CM2, CM3 and CM4 respectively. The CMs were activated in CO{sub 2} surrounding at 800°C for 1 hour to produce activated carbon monolith electrodes (ACM1, ACM2, ACM3 and ACM4). The physical properties of the CMs and ACMs were investigated using X-ray diffraction, field emission scanning electron microscopy (FESEM) and N{sub 2} adsorption-desorption isotherm techniques. ACMs were used as electrode to fabricate symmetry supercapacitormore » cells and the cells’ performances were investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) standard techniques. In this paper we report the physical and electrochemical properties of the ACM electrodes by analyzing the influence of the carbonization temperature on these properties.« less

Ionic Liquid Catalyzed Electrolyte for Electrochemical Polyaniline Supercapacitors

NASA Astrophysics Data System (ADS)

Inamdar, A. I.; Im, Hyunsik; Jung, Woong; Kim, Hyungsang; Kim, Byungchul; Yu, Kook-Hyun; Kim, Jin-Sang; Hwang, Sung-Min

2013-05-01

The effect of different wt.% of ionic liquid "1,6-bis (trimethylammonium-1-yl) hexane tetrafluoroborate" in 0.5 M LiClO4+PC electrolyte on the supercapacitor properties of polyaniline (PANI) thin film are investigated. The PANI film is synthesized using electropolymerization of aniline in the presence of sulfuric acid. The electrochemical properties of the PANI thin film are studied by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) measurements. The optimum amount of the ionic liquid is found to be 2 wt.% which provides better ionic conductivity of the electrolyte. The highest specific capacitance of 259 F/g is obtained using the 2 wt.% electrolyte. This capacitance remains at up to 208 F/g (80% capacity retention) after 1000 charge-discharge cycles at a current density of 0.5 mA/g. The PANI film in the 2 wt.% ionic liquid catalyzed 0.5 M LiClO4+PC electrolyte shows small electrochemical resistance, better rate performance and higher cyclability. The increased ionic conductivity of the 2 wt.% ionic liquid catalyzed electrolyte causes a reduction in resistance at the electrode/electrolyte interface, which can be useful in electrochemically-preferred power devices for better applicability.

Doped Graphene for DNA Analysis: the Electrochemical Signal is Strongly Influenced by the Kind of Dopant and the Nucleobase Structure

PubMed Central

Tian, Huidi; Wang, Lu; Sofer, Zdenek; Pumera, Martin; Bonanni, Alessandra

2016-01-01

Doping graphene with heteroatoms can alter the electronic and electrochemical properties of the starting material. Contrasting properties should be expected when the doping is carried out with electron donating species (n-type dopants) or with electron withdrawing species (p-type dopants). This in turn can have a profound influence on the electroanalytical performance of the doped material being used for the detection of specific probes. Here we investigate the electrochemical oxidation of DNA bases adenine, guanine, thymine and cytosine on two heteroatom-doped graphene platforms namely boron-doped graphene (p-type dopant) and nitrogen-doped graphene (n-type dopant). We found that overall, boron–doped graphene provided the best response in terms of electrochemical signal sensitivity for all bases. This is due to the electron deficiency of boron-doped graphene, which can promote the oxidation of DNA bases, as opposed to nitrogen-doped graphene which possesses an excess of electrons. Moreover, also the structure of the nucleobase was found to have significant influence on the obtained signal. Our study may open new frontiers in the electrochemical detection of DNA bases which is the first step for label-free DNA analysis. PMID:27623951

Electrocatalytic interface based on novel carbon nanomaterials for advanced electrochemical sensors

DOE PAGES

Zhou, Ming; Guo, Shaojun

2015-07-17

The rapid development of nanoscience and nanotechnology provides new opportunities for the sustainable progress of nanoscale catalysts (i.e., nanocatalysts). The introduction of nanocatalysts into electronic devices implants their novel functions into electronic sensing systems, resulting in the testing of many advanced electrochemical sensors and the fabrication of some highly sensitive, selective, and stable sensing platforms. In this Review, we will summarize recent significant progress on exploring advanced carbon nanomaterials (such as carbon nanotubes, graphene, highly ordered mesoporous carbons, and electron cyclotron resonance sputtered nanocarbon film) as nanoscale electrocatalysts (i.e., nanoelectrocatalysts) for constructing the catalytic nanointerfaces of electronic devices to achievemore » high-sensitivity and high-selectivity electrochemical sensors. Furthermore, different mechanisms for the extraordinary and unique electrocatalytic activities of these carbon nanomaterials will be also highlighted, compared and discussed. An outlook on the future trends and developments in this area will be provided at the end. Notably, to elaborate the nature of carbon nanomaterial, we will mainly focus on the electrocatalysis of single kind of carbon materials rather than their hybrid composite materials. As a result, we expect that advanced carbon nanomaterials with unique electrocatalytic activities will continue to attract increasing research interest and lead to new opportunities in various fields of research.« less

High Surface Area Dendrite Nanoelectrodes for Electrochemistry

NASA Astrophysics Data System (ADS)

Nesbitt, Nathan; Glover, Jennifer; Goyal, Saurabh; Simidjiysky, Svetoslav; Naughton, Michael

2014-03-01

Solution-based electrodeposition of metal using a low ion concentration, surface passivation agents, and/or electrochemical crystal conditioning has allowed for the formation of high surface area metal electrodes, useful for Raman spectroscopy and electrochemical sensors. Additionally, high frequency electrical oscillations have been used to electrically connect co-planar electrodes, a process called directed electrochemical nanowire assembly (DENA). These approaches aim to control the crystal face that metal atoms in solution will nucleate onto, thus causing anisotropic growth of metal crystals. However, DENA has not been used to create high surface area electrodes, and no study has been conducted on the effect of micron-scale surface topography on the initial nucleation of metal crystals on the electrode surface. When DENA is used to create a high surface area electrode, such a texture has a strong impact on the subsequent topography of the three dimensional dendritic structures by limiting the areal density of crystals on the electrode surface. Such structures both demonstrate unique physics concerning the nucleation of metal dendrites, and offer a unique and highly facile fabrication method of high surface area electrodes, useful for chemical and biological sensing. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. (DGE-1258923).

Electrocatalytic interface based on novel carbon nanomaterials for advanced electrochemical sensors

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

Zhou, Ming; Guo, Shaojun

The rapid development of nanoscience and nanotechnology provides new opportunities for the sustainable progress of nanoscale catalysts (i.e., nanocatalysts). The introduction of nanocatalysts into electronic devices implants their novel functions into electronic sensing systems, resulting in the testing of many advanced electrochemical sensors and the fabrication of some highly sensitive, selective, and stable sensing platforms. In this Review, we will summarize recent significant progress on exploring advanced carbon nanomaterials (such as carbon nanotubes, graphene, highly ordered mesoporous carbons, and electron cyclotron resonance sputtered nanocarbon film) as nanoscale electrocatalysts (i.e., nanoelectrocatalysts) for constructing the catalytic nanointerfaces of electronic devices to achievemore » high-sensitivity and high-selectivity electrochemical sensors. Furthermore, different mechanisms for the extraordinary and unique electrocatalytic activities of these carbon nanomaterials will be also highlighted, compared and discussed. An outlook on the future trends and developments in this area will be provided at the end. Notably, to elaborate the nature of carbon nanomaterial, we will mainly focus on the electrocatalysis of single kind of carbon materials rather than their hybrid composite materials. As a result, we expect that advanced carbon nanomaterials with unique electrocatalytic activities will continue to attract increasing research interest and lead to new opportunities in various fields of research.« less

Development of the Electrochemical Biosensor for Organophosphate Chemicals Using CNT/Ionic Liquid Bucky Gel Electrode

DTIC Science & Technology

2010-04-01

www.elsevier .com/locate /e lecomDevelopment of the electrochemical biosensor for organophosphate chemicals using CNT/ ionic liquid bucky gel electrode Bong...hydrolase Ionic liquid CNT Electrochemical property1388-2481/$ - see front matter 2009 Elsevier B.V. A doi:10.1016/j.elecom.2009.01.006 * Corresponding...kaist.ac.kr (S.Y. Lee), whhOrganophosphorus hydrolase (OPH) immobilized on CNT/ ionic liquid (IL) electrodes were prepared by using three different intrinsic

Ferrocene conjugated oligonucleotide for electrochemical detection of DNA base mismatch.

PubMed

Hasegawa, Yusuke; Takada, Tadao; Nakamura, Mitsunobu; Yamana, Kazushige

2017-08-01

We describe the synthesis, binding, and electrochemical properties of ferrocene-conjugated oligonucleotides (Fc-oligos). The key step for the preparation of Fc-oligos contains the coupling of vinylferrocene to 5-iododeoxyuridine via Heck reaction. The Fc-conjugated deoxyuridine phosphoramidite was used in the Fc-oligonucleotide synthesis. We show that thiol-modified Fc-oligos deposited onto gold electrodes possess potential ability in electrochemical detection of DNA base mismatch. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrochemical immunosensor assay (EIA) for sensitive detection of E. coli O157:H7 with signal amplification on a SG-PEDOT-AuNPs electrode interface.

PubMed

Guo, Yuna; Wang, Yu; Liu, Su; Yu, Jinghua; Wang, Hongzhi; Cui, Min; Huang, Jiadong

2015-01-21

A novel electrochemical immunosensor assay (EIA) for highly sensitive and specific detection of Escherichia coli O157:H7 has been developed. This immunosensor is constructed by the assembly of capture antibody on SG-PEDOT-AuNPs composites modified glass carbon electrode. In the presence of target E. coli O157:H7, horseradish peroxidase (HRP)-labeled antibody is captured on the electrode surface to form a sandwich-type system via the specific identification. As a result, E. coli O157:H7 detection is realized by outputting a redox current from electro-reduction of hydrogen peroxide reaction catalyzed by HRP. In our assay, the combination of the unique properties of sulfonated graphene (SG) and gold nanoparticles (AuNPs) can not only accelerate electron transfer on electrode interface, but also provide an excellent scaffold for the conjugation of capture antibody that significantly improves the target capture efficiency and enhances the sensitivity of the biosensor. The results reveal the calibration plot obtained for E. coli O157:H7 is approximately linear from 7.8 × 10-7.8 × 10(6) colony-forming unit (cfu) mL(-1) with the limit of detection of 3.4 × 10 cfu mL(-1). In addition, the biosensor has been successfully applied to the quantitative assay of E. coli O157:H7 in synthetic samples (spring water and milk). Hence, the developed electrochemical-based immunosensor might provide a useful and practical tool for E. coli O157:H7 determination and related food safety analysis and clinical diagnosis.

Core-shell iron oxide-layered double hydroxide: High electrochemical sensing performance of H2O2 biomarker in live cancer cells with plasma therapeutics.

PubMed

Asif, Muhammad; Liu, Hongwei; Aziz, Ayesha; Wang, Haitao; Wang, Zhengyun; Ajmal, Muhammad; Xiao, Fei; Liu, Hongfang

2017-11-15

In this work, we develop a new type of multifunctional core-shell nanomaterial by controllable integration of CuAl layered double hydroxides (LDHs) over the surface of iron oxides (Fe 3 O 4 ) nanospheres (NSs) to fabricate (Fe 3 O 4 @CuAl NSs) hybrid material with interior tunability of LDH phase and explore its practical application in ultrasensitive detection of emerging biomarker, i.e., H 2 O 2 as cancer diagnostic probe. In addition, atmospheric pressure plasmas (APPs) have also been used as potential therapeutic approach for cancer treatment. Due to the synergistic combination of p-type semiconductive channels of LDHs with multi-functional properties, unique morphology and abundant surface active sites, the Fe 3 O 4 @CuAl NSs modified electrode exhibited attractive electrocatalytic activity towards H 2 O 2 reduction. Under the optimized conditions, the proposed biosensor demonstrated striking electrochemical sensing performances to H 2 O 2 including linear range as broad as 8 orders of magnitude, low real detection limit of 1nM (S/N = 3), high sensitivity, good reproducibility and long-term stability. Arising from the superb efficiency, the electrochemical biosensor has been used for in vitro determination of H 2 O 2 concentrations in human urine and serum samples prior to and following the intake of coffee, and real-time monitoring of H 2 O 2 efflux from different cancer cell lines in normal state and after plasma treatment. We believe that this novel nano-platform of structurally integrated core-shell nanohybrid materials combined with APPs will enhance diagnostic as well as therapeutic window for cancer diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

An efficient signal-on aptamer-based biosensor for adenosine triphosphate detection using graphene oxide both as an electrochemical and electrochemiluminescence signal indicator.

PubMed

Huang, Xiang; Li, Yuqin; Zhang, Xiaoshan; Zhang, Xin; Chen, Yaowen; Gao, Wenhua

2015-09-07

An efficient aptasensor was developed in which graphene oxide (GO) was employed as an indicator for both electrochemical impedance spectroscopy and electrochemiluminescence (ECL) signal generation. The aptasensor was fabricated by self-assembling the ECL probe of a thiolated adenosine triphosphate binding aptamer (ABA) tagged with a Ru complex (Ru(bpy)3(2+) derivatives) onto the surface of gold nanoparticle (AuNP) modified glassy carbon electrode (GCE). ABA immobilized onto AuNP modified GCE could strongly adsorb GO due to the strong π-π interaction between ABA and graphene oxide; ECL quenching of the Ru complex then takes place because of energy transfer and electron transfer, and a large increase of the electron transfer resistance (Ret) of the electrode. While in the presence of target adenosine triphosphate (ATP), the ABA prefers to form ABA-ATP bioaffinity complexes, which have weak affinity to graphene oxide and keep the graphene oxide away from the electrode surface, thus allowing the ECL signal enhancement, and in conjunction with the decrease of the Ret. Because of the high ECL quenching efficiency, unique structure, and electronic properties of graphene oxide, the Ret and ECL intensity versus the logarithm of ATP concentration was linear in the wide range from 10 pM to 10 nM with an ultra-low detection limit of 6.7 pM to 4.8 pM, respectively. The proposed aptasensor exhibited excellent reproducibility, stability, and outstanding selectivity, and ATP could be effectively distinguished from its analogues. More significantly, this efficient ECL aptasensor strategy based on GO acting both as an electrochemical and ECL signal indicator is general and can be easily extended to other biological binding events.

Mesostructured niobium-doped titanium oxide-carbon (Nb-TiO2-C) composite as an anode for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Hwang, Keebum; Sohn, Hiesang; Yoon, Songhun

2018-02-01

Mesostructured niobium (Nb)-doped TiO2-carbon (Nb-TiO2-C) composites are synthesized by a hydrothermal process for application as anode materials in Li-ion batteries. The composites have a hierarchical porous structure with the Nb-TiO2 nanoparticles homogenously distributed throughout the porous carbon matrix. The Nb content is controlled (0-10 wt%) to investigate its effect on the physico-chemical properties and electrochemical performance of the composite. While the crystalline/surface structure varied with the addition of Nb (d-spacing of TiO2: 0.34-0.36 nm), the morphology of the composite remained unaffected. The electrochemical performance (cycle stability and rate capability) of the Nb-TiO2-C composite anode with 1 wt% Nb doping improved significantly. First, a full cut-off potential (0-2.5 V vs. Li/Li+) of Nb-doped composite anode (1 wt%) provides a higher energy utilization than that of the un-doped TiO2-C anode. Second, Nb-TiO2-C composite anode (1 wt%) exhibits an excellent long-term cycle stability (100% capacity retention, 297 mAh/g at 0.5 C after 100 cycles and 221 mAh/g at 2 C after 500 cycles) and improved rate-capability (192 mAh/g at 5 C), respectively (1 C: 150 mA/g). The superior electrochemical performance of Nb-TiO2-C (1 wt%) could be attributed to the synergistic effect of improved electronic conductivity induced by optimal Nb doping (1 wt%) and lithium-ion penetration (high diffusion kinetics) through unique pore structures.

Luminescent Properties of Semiconductor Electrodes.

DTIC Science & Technology

1985-08-15

S. Gottesfeld, and N. Croitoru, J. Electroanal. Chem. Interfac. Electrochem. 150, 571 (1983). 71. H. H. Streckert, H. Van Ryswyk, R. N. Biagioni , and...Johnson, W. S. Hobson, and A. B. Ellis, unpublished observations. 104. P. M. Smiley, R. N. Biagioni , and A. B. Ellis, J. Electrochem. Soc. 131, 1068

Electrochemical Properties of Poly(Anthraquinonyl Sulfide)/Graphene Sheets Composites as Electrode Materials for Electrochemical Capacitors.

PubMed

Lee, Wonkyun; Suzuki, Shinya; Miyayama, Masaru

2014-07-30

Poly(anthraquinonyl sulfide) (PAQS)/graphene sheets (GSs) composite was synthesized through in situ polymerization to evaluate its performance as an electrode material for electrochemical capacitors. PAQS was successfully synthesized in the presence of GSs with uniform distribution. PAQS/GSs showed a pair of reversible redox peaks at around 0 V ( vs. Ag/AgCl). The specific capacitance of PAQS/GSs was 349 F·g -1 (86 mAh·g -1 ) at a current density of 500 mA·g -1 , and a capacitance of 305 F·g -1 was maintained even at a high current density of 5000 mA·g -1 . The in situ polymerization of PAQS with GSs facilitated their interaction and enabled faster charge transfer and redox reaction, resulting in enhanced electrode properties.

Preparation of Ni3B2O6 nanosheet-based flowerlike architecture by a precursor method and its electrochemical properties in lithium-ion battery

NASA Astrophysics Data System (ADS)

Liang, Pan; Du, Lu; Wang, Xia; Liu, Zhi-Hong

2014-11-01

A novel flower-like nickel borate of Ni3B2O6 nanostructure was prepared through a hydrothermal treatment and sequential thermal decomposition of precursor without employing any template or surfactant. All the samples were characterized by XRD, IR, XPS, TG-DTA, nitrogen adsorption, SEM and TEM. The flower-like Ni3B2O6 nanostructure was self-assembled by nanosheets with the thickness of about 40 nm. The electrochemical properties in lithium-ion battery of flower-like Ni3B2O6 nanostructure were studied by the cyclic voltammetry, galvanostatic cycling test, and electrochemical impedance spectroscopy, which showed it had a high initial discharge capacity and a good reversibility.

Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

PubMed Central

Movlaee, Kaveh; Ganjali, Mohmmad Reza; Norouzi, Parviz

2017-01-01

Iron oxide nanostructures (IONs) in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (bio)chemical substances. PMID:29168771

Molecularly imprinted electrochemical sensor based on amine group modified graphene covalently linked electrode for 4-nonylphenol detection.

PubMed

Chen, Hong-Jun; Zhang, Zhao-Hui; Cai, Rong; Chen, Xing; Liu, Yu-Nan; Rao, Wei; Yao, Shou-Zhuo

2013-10-15

In this work, an imprinted electrochemical sensor based on electrochemical reduced graphene covalently modified carbon electrode was developed for the determination of 4-nonylphenol (NP). An amine-terminated functional graphene oxide was covalently modified onto the electrode surface with diazonium salt reactions to improve the stability and reproducibility of the imprinted sensor. The electrochemical properties of each modified electrodes were investigated with differential pulse voltammetry (DPV). The electrochemical characteristic of the imprinted sensor was also investigated using electrochemical impedance spectroscopy (EIS) in detail. The response currents of the imprinted electrode exhibited a linear relationship toward 4-nonylphenol concentration ranging from 1.0 × 10(-11) to 1.0 × 10(-8) gm L(-1) with the detection limit of 3.5 × 10(-12) gm L(-1) (S/N=3). The fabricated electrochemical imprinted sensor was successfully applied to the detection of 4-nonylphenol in rain and lake water samples. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

Tin Oxide Crystals Exposed by Low-Energy {110} Facets for Enhanced Electrochemical Heavy Metal Ions Sensing: X-ray Absorption Fine Structure Experimental Combined with Density-Functional Theory Evidence.

PubMed

Jin, Zhen; Yang, Meng; Chen, Shao-Hua; Liu, Jin-Huai; Li, Qun-Xiang; Huang, Xing-Jiu

2017-02-21

Herein, we revealed that the electrochemical behaviors on the detection of heavy metal ions (HMIs) would largely rely on the exposed facets of SnO 2 nanoparticles. Compared to the high-energy {221} facet, the low-energy {110} facet of SnO 2 possessed better electrochemical performance. The adsorption/desorption tests, density-functional theory (DFT) calculations, and X-ray absorption fine structure (XAFS) studies showed that the lower barrier energy of surface diffusion on {110} facet was critical for the superior electrochemical property, which was favorable for the ions diffusion on the electrode, and further leading the enhanced electrochemical performance. Through the combination of experiments and theoretical calculations, a reliable interpretation of the mechanism for electroanalysis of HMIs with nanomaterials exposed by different crystal facets has been provided. Furthermore, it provides a deep insight into understanding the key factor to improve the electrochemical performance for HMIs detection, so as to design high-performance electrochemical sensors.

Electrocatalytic properties of graphite nanofibers-supported platinum catalysts for direct methanol fuel cells.

PubMed

Park, Soo-Jin; Park, Jeong-Min; Seo, Min-Kang

2009-09-01

Graphite nanofibers (GNFs) treated at various temperatures were used as carbon supports to improve the efficiency of PtRu catalysts. The electrochemical properties of the PtRu/GNFs catalysts were then investigated to evaluate their potential for application in DMFCs. The results indicated that the particle size and dispersibility of PtRu in the catalysts were changed by heat treatment, and the electrochemical activity of the catalysts was improved. Consequently, it was found that heat treatments could have an influence on the surface and structural properties of GNFs, resulting in enhancing an electrocatalytic activity of the catalysts for DMFCs.

Preparation, structure, and unique redox properties of mono-, bis-, and Tris(diarylmethylene)-1,3,5-trithianes and related compounds

PubMed

Suzuki; Yoshino; Nishida; Ohkita; Tsuji

2000-09-08

A series of 1,3,5-trithianes 1-3 having diarylmethylene units were designed as novel electron donors giving highly colored cationic species upon oxidation. They were prepared along with the dithiane and dithiazine derivatives 4-6 by the reactions of lithiated heterocycles with diaryl ketones followed by dehydration. Voltammetric analyses indicate that a large structural change and/or transannular bonding are induced during their electrochemical oxidation. Mono(diarylmethylene) derivative 1a exhibits electrochromism with vivid change in color from faintly yellow to deep blue with concomitant rotation around the exocyclic bond. Both of the strongly colored salts obtained upon oxidation of 2,4-bis- and 2,4,6-tris(diarylmethylene)-1,3,5-trithianes (2aa and 3) consist of the dications with a 1,2,4-trithiane ring, suggesting the easy skeletal rearrangement of the transannular dications with a trithiabicylo[3.1.0]hexane ring. Upon reduction of these salts were obtained bright yellow 12 and 13, respectively, with high electron-donating properties due to the tetraarylbutadiene-type conjugation, thus giving another class of electrochromic compounds.

Aluminum-Scandium Alloys: Material Characterization, Friction Stir Welding, and Compatibility With Hydrogen Peroxide (MSFC Center Director's Discretionary Fund Final Report, Proj. No. 04-14)

NASA Technical Reports Server (NTRS)

Lee, J. A.; Chen, P. S.

2004-01-01

This Technical Memorandum describes the development of several high-strength aluminum (Al) alloys that are compatible with hydrogen peroxide (H2O2) propellant for NASA Hypersonic-X (Hyper-X) vehicles fuel tanks and structures. The yield strengths for some of these Al-magnesium-based alloys are more than 3 times stronger than the conventional 5254-H112 Al alloy, while maintaining excellent H2O2 compatibility similar to class 1 5254 alloy. The alloy development strategy is to add scandium, zirconium, and other transitional metals with unique electrochemical properties, which will not act as catalysts, to decompose the highly concentrated 90 percent H2O2. Test coupons are machined from sheet metals for H2O2 long-term exposure testing and mechanical properties testing. In addition, the ability to weld the new alloys using friction stir welding has also been explored. The new high-strength alloys could represent an enabling material technology for Hyper-X vehicles, where flight weight reduction is a critical requirement.

Wire-in-Tube IrOx Architectures: Alternative Label-Free Immunosensor for Amperometric Immunoassay toward α-Fetoprotein.

PubMed

Li, Qingling; Liu, Dali; Xu, Lin; Xing, Ruiqing; Liu, Wei; Sheng, Kuang; Song, Hongwei

2015-10-14

A sensitive, label-free immunosensor based on iridium oxide (IrOx, 0≤x≤2) nanofibers, which were synthesized through a simple one-spinneret electrospinning method, was first developed for immunoassay of the cancer biomarker α-fetoprotein (AFP). The specific wire-in-tube nanostructure could be obtained and the composition of IrOx nanofibers also could be controlled through changing the annealing temperature. The unique structure and properties of IrOx nanofibers obtained at 500 °C not only led to increased electrode surface area and accelerated electron transfer kinetics but also could provide a highly stable matrix for the convenient conjugation of biomolecules together with chitosan (CS). The good electrochemical properties of the IrOx-nanofiber-modified immunosensor allowed one to detect AFP over a wide concentration range from 0.05 to 150 ng/mL, with a detection limit of 20 pg/mL. The proposed immunosensor also has been used to determine AFP in human serum with satisfactory results. The present protocol was shown to be quite promising for clinical screening of cancer biomarkers and point-of-care diagnostics applications.

Organometallic compounds: an opportunity for chemical biology?

PubMed

Patra, Malay; Gasser, Gilles

2012-06-18

Organometallic compounds are renowned for their remarkable applications in the field of catalysis, but much less is known about their potential in chemical biology. Indeed, such compounds have long been considered to be either unstable under physiological conditions or cytotoxic. As a consequence, little attention has been paid to their possible utilisation for biological purposes. Because of their outstanding physicochemical properties, which include chemical stability, structural diversity and unique photo- and electrochemical properties, however, organometallic compounds have the ability to play a leading role in the field of chemical biology. Indeed, remarkable examples of the use of such compounds-notably as enzyme inhibitors and as luminescent agents-have recently been reported. Here we summarise recent advances in the use of organometallic compounds for chemical biology purposes, an area that we define as "organometallic chemical biology". We also demonstrate that these recent discoveries are only a beginning and that many other organometallic complexes are likely to be found useful in this field of research in the near future. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchical nanorods constructed by Mn2Mo3O8@reduced graphene oxide nanosheet arrays with enhanced lithium storage properties

NASA Astrophysics Data System (ADS)

Zhang, Lifeng; Shen, Kechao; He, Wenjie; Liu, Yi; Yin, Lixiong; Guo, Shouwu

2018-10-01

3D hierarchical nanorods of Mn2Mo3O8@reduced graphene oxide (rGO) nanohybrid assembled with nanosheet arrays have been fabricated via a facile solvothermal process combined with subsequent anneal. It is identified that the annealing temperature and the input amount of graphene oxide (GO) are critical to form such unique Mn2Mo3O8@rGO nanostructure, whose hierarchical nanorods (ca. 470 nm of diameter) are constructed by vertical nanosheet arrays (30 ± 5 nm average thickness for individual nanosheet). As an anode material for lithium ion batteries, the hierarchical Mn2Mo3O8@rGO electrode delivers superior capability and rate properties to the compared nanostructure synthesized at different annealing temperature. The enhanced electrochemical performance is attributed to the rational combination of 3D nanorods and 2D nanosheets, which is beneficial to the fast penetration of electrolytes and thus provide more reactive facets, shorten the diffusion paths of Li+ and facilitate the electron conduction.

Nanomaterials-based biosensors for detection of microorganisms and microbial toxins.

PubMed

Sutarlie, Laura; Ow, Sian Yang; Su, Xiaodi

2017-04-01

Detection of microorganisms and microbial toxins is important for health and safety. Due to their unique physical and chemical properties, nanomaterials have been extensively used to develop biosensors for rapid detection of microorganisms with microbial cells and toxins as target analytes. In this paper, the design principles of nanomaterials-based biosensors for four selected analyte categories (bacteria cells, toxins, mycotoxins, and protozoa cells), closely associated with the target analytes' properties is reviewed. Five signal transducing methods that are less equipment intensive (colorimetric, fluorimetric, surface enhanced Raman scattering, electrochemical, and magnetic relaxometry methods) is described and compared for their sensory performance (in term oflimit of detection, dynamic range, and response time) for all analyte categories. In the end, the suitability of these five sensing principles for on-site or field applications is discussed. With a comprehensive coverage of nanomaterials, design principles, sensing principles, and assessment on the sensory performance and suitability for on-site application, this review offers valuable insight and perspective for designing suitable nanomaterials-based microorganism biosensors for a given application. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evidence of a reverse side-chain effect of tris(pentafluoroethyl)trifluorophosphate [FAP]-based ionic liquids against pathogenic bacteria.

PubMed

Weyhing-Zerrer, Nadine; Kalb, Roland; Oßmer, Rolf; Rossmanith, Peter; Mester, Patrick

2018-02-01

Increased interest in ionic liquids (ILs) is due to their designable and tunable unique physicochemical properties, which are utilized for a wide variety of chemical and biotechnological applications. ILs containing the tris(pentafluoroethyl)trifluorophosphate ([FAP]) anion have been shown to have excellent hydrolytic, electrochemical and thermal stability and have been successfully used in various applications. In the present study the influence of the cation on the toxicity of the [FAP] anion was investigated. Due to the properties of [FAP] ILs, the IL-toxicity of seven cations with [FAP] compared to [Cl] was examined by determination of minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) on six Gram-positive and six Gram-negative clinically-relevant bacteria. For the first time, to our knowledge, the results provide evidence for a decrease in toxicity with increasing alkyl side-chain length, indicating that the combination of both ions is responsible for this 'reverse side-chain effect'. These findings could portend development of new non-toxic ILs as green alternatives to conventional organic solvents. Copyright © 2017 Elsevier Inc. All rights reserved.

Benchmarking Density Functional Theory Based Methods To Model NiOOH Material Properties: Hubbard and van der Waals Corrections vs Hybrid Functionals.

PubMed

Zaffran, Jeremie; Caspary Toroker, Maytal

2016-08-09

NiOOH has recently been used to catalyze water oxidation by way of electrochemical water splitting. Few experimental data are available to rationalize the successful catalytic capability of NiOOH. Thus, theory has a distinctive role for studying its properties. However, the unique layered structure of NiOOH is associated with the presence of essential dispersion forces within the lattice. Hence, the choice of an appropriate exchange-correlation functional within Density Functional Theory (DFT) is not straightforward. In this work, we will show that standard DFT is sufficient to evaluate the geometry, but DFT+U and hybrid functionals are required to calculate the oxidation states. Notably, the benefit of DFT with van der Waals correction is marginal. Furthermore, only hybrid functionals succeed in opening a bandgap, and such methods are necessary to study NiOOH electronic structure. In this work, we expect to give guidelines to theoreticians dealing with this material and to present a rational approach in the choice of the DFT method of calculation.

Formation of Sn-M (M=Fe, Al, Ni) alloy nanoparticles by DC arc-discharge and their electrochemical properties as anodes for Li-ion batteries

NASA Astrophysics Data System (ADS)

Gao, Song; Huang, Hao; Wu, Aimin; Yu, Jieyi; Gao, Jian; Dong, Xinglong; Liu, Chunjing; Cao, Guozhong

2016-10-01

A direct current arc-discharge method was applied to prepare the Sn-M (M=Fe, Al, Ni) bi-alloy nanoparticles. Thermodynamic is introduced to analyze the energy circumstances for the formation of the nanoparticles during the physical condensation process. The electrochemical properties of as-prepared Sn-M alloy nanoparticles are systematically investigated as anodes of Li-ion batteries. Among them, Sn-Fe nanoparticles electrode exhibits high Coulomb efficiency (about 71.2%) in the initial charge/discharge (257.9 mA h g-1/366.6 mA h g-1) and optimal cycle stability (a specific reversible capacity of 240 mA h g-1 maintained after 20 cycles) compared with others. Large differences in the electrochemical behaviors indicate that the chemical composition and microstructure of the nanoparticles determine the lithium-ion storage properties and the long-term cyclic stability during the charge/discharge process.

Enhanced electrochemical properties of LiFePO4 (LFP) cathode using the carboxymethyl cellulose lithium (CMC-Li) as novel binder in lithium-ion battery.

PubMed

Qiu, Lei; Shao, Ziqiang; Wang, Daxiong; Wang, Wenjun; Wang, Feijun; Wang, Jianquan

2014-10-13

Novel water-based binder CMC-Li is synthesized using cotton as raw material. The mechanism of the CMC-Li as a binder is reported. Electrochemical properties of batteries cathodes based on commercially available lithium iron phosphate (LiFePO4, LFP) and CMC-Li as a water-soluble binder are investigated. CMC-Li is a novel lithium-ion binder. Compare with conventional poly(vinylidene fluoride) (PVDF) binder, and the battery with CMC-Li as the binder retained 97.8% of initial reversible capacity after 200 cycles at 176 mAh g(-1), which is beyond the theoretical specific capacity of LFP. Constant current charge-discharge test results demonstrate that the LFP electrode using CMC-Li as the binder has the highest rate capability, follow closely by that using PVDF binder. The batteries have good electrochemical property, outstanding pollution-free and excellent stability. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sequence Effects in Conjugated Donor-Acceptor Trimers and Polymers.

PubMed

Zhang, Shaopeng; Hutchison, Geoffrey R; Meyer, Tara Y

2016-06-01

To investigate the sequence effect on donor-acceptor conjugated oligomers and polymers, the trimeric isomers PBP and BPP, comprising dialkoxy phenylene vinylene (P), benzothiadiazole vinylene (B), and alkyl endgroups with terminal olefins, are synthesized. Sequence effects are evident in the optical/electrochemical properties and thermal properties. Absorption maxima for PBP and BPP differ by 41 nm and the electrochemical band gaps by 0.1 V. The molar emission intensity is five times greater in PBP than BPP. Both trimers are crystalline and the melting points differ by 17 °C. The PBP and BPP trimers are used as macromonomers in an acyclic diene metathesis polymerization to give PolyPBP and PolyBPP. The optical and electrochemical properties are similar to those of their trimer precursors-sequence effects are still evident. These results suggest that sequence is a tunable variable for electronic materials and that the polymerization of oligomeric sequences is a useful approach to introducing sequence into polymers. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical Sensing Applications of ZnO Nanomaterials

PubMed Central

Chaudhary, Savita; Umar, Ahmad; Bhasin, K. K.

2018-01-01

Recent advancement in nanoscience and nanotechnology has witnessed numerous triumphs of zinc oxide (ZnO) nanomaterials due to their various exotic and multifunctional properties and wide applications. As a remarkable and functional material, ZnO has attracted extensive scientific and technological attention, as it combines different properties such as high specific surface area, biocompatibility, electrochemical activities, chemical and photochemical stability, high-electron communicating features, non-toxicity, ease of syntheses, and so on. Because of its various interesting properties, ZnO nanomaterials have been used for various applications ranging from electronics to optoelectronics, sensing to biomedical and environmental applications. Further, due to the high electrochemical activities and electron communication features, ZnO nanomaterials are considered as excellent candidates for electrochemical sensors. The present review meticulously introduces the current advancements of ZnO nanomaterial-based chemical sensors. Various operational factors such as the effect of size, morphologies, compositions and their respective working mechanisms along with the selectivity, sensitivity, detection limit, stability, etc., are discussed in this article. PMID:29439528

Electrochemical Grafting of Graphene Nano Platelets with Aryl Diazonium Salts.

PubMed

Qiu, Zhipeng; Yu, Jun; Yan, Peng; Wang, Zhijie; Wan, Qijin; Yang, Nianjun

2016-10-26

To vary interfacial properties, electrochemical grafting of graphene nano platelets (GNP) with 3,5-dichlorophenyl diazonium tetrafluoroborate (aryl-Cl) and 4-nitrobenzene diazonium tetrafluoroborate (aryl-NO 2 ) was realized in a potentiodynamic mode. The covalently bonded aryl layers on GNP were characterized using atomic force microscopy and X-ray photoelectron spectroscopy. Electrochemical conversion of aryl-NO 2 into aryl-NH 2 was conducted. The voltammetric and impedance behavior of negatively and positively charged redox probes (Fe(CN) 6 3-/4- and Ru(NH 3 ) 6 2+/3+ ) on three kinds of aryl layers grafted on GNP reveal that their interfacial properties are determined by the charge states of redox probes and reactive terminal groups (-Cl, -NO 2 , -NH 2 ) in aryl layers. On aryl-Cl and aryl-NH 2 garted GNP, selective and sensitive monitoring of positively charged lead ions as well as negatively charged nitrite and sulfite ions was achieved, respectively. Such a grafting procedure is thus a perfect way to design and control interfacial properties of graphene.

Synthesis and electrochemical properties of Ti-doped DLC films by a hybrid PVD/PECVD process

NASA Astrophysics Data System (ADS)

Jo, Yeong Ju; Zhang, Teng Fei; Son, Myoung Jun; Kim, Kwang Ho

2018-03-01

Low electrical conductivity and poor adhesion to metallic substrates are the main drawbacks of diamond-like carbon (DLC) films when used in electrode applications. In this study, Ti-doped DLC films with various Ti contents were synthesized on metal Ti substrates by a hybrid PVD/PECVD process, where PECVD was used for deposition of DLC films and PVD was used for Ti doping. The effects of the Ti doping ratio on the microstructure, adhesion strength, and electrical and electrochemical properties of the DLC films were systematically investigated. An increase in the Ti content led to increased surface roughness and a higher sp2/sp3 ratio of the Ti-DLC films. Ti atoms existed as amorphous-phase Ti carbide when the Ti doping ratio was less than 2.8 at.%, while the nanocrystalline TiC phase was formed in DLC films when the Ti doping ratio was exceeded 4.0 at.%. The adhesion strength, electrical resistivity, electrochemical activity and reversibility of the DLC films were greatly improved by Ti doping. The influence of Ti doping ratio on the electrical and electrochemical properties of the DLC films were also investigated and the best performance was obtained at a Ti content of 2.8 at.%.

Investigation on Electrochemical Properties of Polythiophene Nanocomposite with Graphite Derivatives as Supercapacitor Material on Breath Figure-Decorated PMMA Electrode

NASA Astrophysics Data System (ADS)

Azimi, Mona; Abbaspour, Mohsen; Fazli, Ali; Setoodeh, Hamideh; Pourabbas, Behzad

2018-03-01

Breath figures have been formed by the direct breath figure method on polymethyl methacrylate electrode sand hexagonal oriented holes with 0.5- to 10- μm2 surface area have been created. Deposition of materials on the electrodes has been performed by the spray-coating method. polythiophene (PTh) nanoparticles, polythiophene-graphene oxide (PTh-GO) and polythiophene-reduced graphene oxide (PTh-G) nanocomposites were synthesized by emulsion polymerization, while characterization of synthetic materials have been carried out by Fourier transform infrared, Χ-ray diffraction, transmission electron microscopy, UV-Vis spectroscopy and field emission scanning electron microscopy techniques. Also, the electrochemical properties of the designed electrodes were investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques. Specific capacitance of porous electrodes coated by PTh nanoparticles, PTh-GO and PTh-G nanocomposites were calculated from cyclic voltammetry curves at 5 mV/s scan rate, andthe values are 3.5 F/g, 16.39 F/g, and 28.68 F/g, respectively. Also, the energy density of each electrode at 5 mV/s scan rate has been calculated and the results show that incorporation of GO and G nanolayers with PTh nanoparticles enhances the electrochemical properties of electrodes.

Effect of the synthesis conditions on the electrochemical properties of LiFePO{sub 4} obtained from NH{sub 4}FePO{sub 4}

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

Prosini, Pier Paolo, E-mail: pierpaolo.prosini@enea.it; Gislon, Paola; Cento, Cinzia

Graphical abstract: - Highlights: • Four different samples of FAP were synthesized by precipitation techniques. • The samples were used as precursors to synthesize electrochemical active LiFePO{sub 4}. • Their morphology, composition, structure and electrochemical performance were studied. • The LiFePO{sub 4} electrochemical performance resulted affected by the preparation method - Abstract: In this paper the morphological, structural and electrochemical properties of crystalline lithium iron phosphate (LiFePO{sub 4}) obtained from ferrous ammonium phosphate (FAP) have been studied. The FAP was obtained following four different processes, namely: (1) homogeneous phase precipitation, (2) heterogeneous phase precipitation from stoichiometric sodium phosphate, (3) heterogeneousmore » phase precipitation from stoichiometric ammonium phosphate, and (4) heterogeneous phase precipitation from over stoichiometric ammonium phosphate. Lithium iron phosphate was prepared by solid state reaction of FAP with lithium hydroxide. In order to evaluate the effect of reaction time and synthesis temperature the LiFePO{sub 4} was prepared varying the heating temperatures (550, 600 and 700 °C) and the reaction times (1 or 2 h). The morphology of the materials was evaluated by scanning electron microscopy while the chemical composition was determined by electron energy loss spectroscopy. X-ray diffraction was used to evaluate phase composition, crystal structure and crystallite size. The so obtained LiFePO{sub 4}'s were fully electrochemical characterized and a correlation was found between the crystal size and the electrochemical performance.« less

Electrochemical evaluation for corrosion resistance of bacterial exopolysaccharides on low carbon steel

USDA-ARS?s Scientific Manuscript database

Corrosion is a global issue that affects safety and economics. There is an increasing demand for bio-based polymers for industrial applications and production of polymers by microorganisms is especially attractive. This work reports on the electrochemical and physical properties of 29 strains or fr...

Unique Cobalt Sulfide/Reduced Graphene Oxide Composite as an Anode for Sodium-Ion Batteries with Superior Rate Capability and Long Cycling Stability.

PubMed

Peng, Shengjie; Han, Xiaopeng; Li, Linlin; Zhu, Zhiqiang; Cheng, Fangyi; Srinivansan, Madhavi; Adams, Stefan; Ramakrishna, Seeram

2016-03-09

Exploitation of high-performance anode materials is essential but challenging to the development of sodium-ion batteries (SIBs). Among all proposed anode materials for SIBs, sulfides have been proved promising candidates due to their unique chemical and physical properties. In this work, a facile solvothermal method to in situ decorate cobalt sulfide (CoS) nanoplates on reduced graphene oxide (rGO) to build CoS@rGO composite is described. When evaluated as anode for SIBs, an impressive high specific capacity (540 mAh g(-1) at 1 A g(-1) ), excellent rate capability (636 mAh g(-1) at 0.1 A g(-1) and 306 mAh g(-1) at 10 A g(-1)), and extraordinarily cycle stability (420 mAh g(-1) at 1 A g(-1) after 1000 cycles) have been demonstrated by CoS@rGO composite for sodium storage. The synergetic effect between the CoS nanoplates and rGO matrix contributes to the enhanced electrochemical performance of the hybrid composite. The results provide a facile approach to fabricate promising anode materials for high-performance SIBs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of boric acid (H3BO3) concentration on the physical properties of electrochemical deposited nickel (Ni) nanowires

NASA Astrophysics Data System (ADS)

Kananathan, J.; Sofiah, A. G. N.; Samykano, M.; Ulakanathan, S.; Lah, N. A. C.; Harun, W. S. W.; Sudhakar, K.; Kadirgama, K.; Ngui, W. K.; Siregar, J. P.

2017-10-01

Authors have investigated the influence of the stabilizer (Boric Acid) concentration during the template-assisted electrochemical deposition of Nickel (Ni) nanowires in Anodic Alumina Oxide (AAO) templates. The synthesis was performed using Ni Sulfate Hexahydrate (NiSO4.6H2O) as metal salts and Boric Acid (H3BO3) as a stabilizer. The mixture of both solutions creates electrolyte and utilized for the electrochemical deposition of Ni nanowires. During the experiment, the boric acid concentration varied between 5 g/L, 37.5 g/L and 60 g/L with a deposition temperature of 80 °C (constant). After the electrochemical deposition process, AAO templates were cleaned with distilled water before dissolution in Sodium Hydroxide (NaOH) solution to obtain the freestanding Ni nanowires. Physical properties of the synthesized Ni nanowires were analyzed using Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDX) and X-ray Diffraction (XRD). The physical properties of obtained Ni nanowires has eloborated by taking into account the effect of boric acid concentration on the surface morphology, growth length, elemental composition and crystal orientation crystal of the synthesized nickel nanowires. The finding exposes that the boric acid concentration does not influence all aspects in the physicals properties of the synthesized Ni nanowires. The boric acid concentration did not affect the surface texture and crystal orientation. However, shorter Ni nanowires obtained as the concentration of boric acid increased.

Insight into the isoelectronic character of azomethines and vinylenes using representative models: a spectroscopic and electrochemical study.

PubMed

Bolduc, Andréanne; Al Ouahabi, Abelaziz; Mallet, Charlotte; Skene, W G

2013-09-20

A series of azomethine and vinylene dyad and triad analogues were prepared. Their absorbance, fluorescence, and redox properties were examined experimentally and theoretically using density functional theory (DFT) calculations. These measurements were done to determine the effect of the heteroatom of the azomethine relative to its all-carbon counterpart and to assess the isoelectronic character of the two bonds. The orientation of the azomethine was found to have little effect on the absorbance, fluorescence, and electrochemical properties. In contrast, the spectral and electrochemical properties were highly contingent on the electronic groups and degree of conjugation. The spectral properties could be tuned 200 nm across the visible region. More importantly, the heteroatom in the conjugated bond was found to give rise to only a 20 nm bathochromic shift in the absorbance and fluorescence spectra. The fluorescence quantum yield (ΦFl) of the vinylene derivatives varied between 5% and 20% with fluorescence quenching occurring by photoisomerization from the E to Z isomers. In contrast, the fluorescence of the analogous azomethine derivatives was completely quenched. The collective spectroscopic and electrochemical ab initio DFT data additionally confirmed that the azomethine and its analogous vinylene are isoelectronic. It was also found that a conjugated thiophene vinylene dyad with primary amines in the α,α'-positions could be prepared and isolated. The compound was stable under aerobic conditions providing electron withdrawing (either ester or nitrile) groups were located in the adjacent positions.

Functional micro/nanostructures: simple synthesis and application in sensors, fuel cells, and gene delivery.

PubMed

Guo, Shaojun; Wang, Erkang

2011-07-19

In order to develop new, high technology devices for a variety of applications, researchers would like to better control the structure and function of micro/nanomaterials through an understanding of the role of size, shape, architecture, composition, hybridization, molecular engineering, assembly, and microstructure. However, researchers continue to face great challenges in the construction of well-defined micro/nanomaterials with diverse morphologies. At the same time, the research interface where micro/nanomaterials meet electrochemistry, analytical chemistry, biomedicine, and other fields provides rich opportunities to reveal new chemical, physical, and biological properties of micro/nanomaterials and to uncover many new functions and applications of these materials. In this Account, we describe our recent progress in the construction of novel inorganic and polymer nanostructures formed through different simple strategies. Our synthetic strategies include wet-chemical and electrochemical methods for the controlled production of inorganic and polymer nanomaterials with well-defined morphologies. These methods are both facile and reliable, allowing us to produce high-quality micro/nanostructures, such as nanoplates, micro/nanoflowers, monodisperse micro/nanoparticles, nanowires, nanobelts, and polyhedron and even diverse hybrid structures. We implemented a series of approaches to address the challenges in the preparation of new functional micro/nanomaterials for a variety of important applications This Account also highlights new or enhanced applications of certain micro/nanomaterials in sensing applications. We singled out analytical techniques that take advantage of particular properties of micro/nanomaterials. Then by rationally tailoring experimental parameters, we readily and selectively obtained different types of micro/nanomaterials with novel morphologies with high performance in applications such as electrochemical sensors, electrochemiluminescent sensors, gene delivery agents, and fuel cell catalysts. We expect that micro/nanomaterials with unique structural characteristics, properties, and functions will attract increasing research interest and will lead to new opportunities in various fields of research.

Selective sodium intercalation into sodium nickel-manganese sulfate for dual Na-Li-ion batteries.

PubMed

Marinova, Delyana M; Kukeva, Rosica R; Zhecheva, Ekaterina N; Stoyanova, Radostina K

2018-05-09

Double sodium transition metal sulfates combine in themselves unique intercalation properties with eco-compatible compositions - a specific feature that makes them attractive electrode materials for lithium and sodium ion batteries. Herein, we examine the intercalation properties of novel double sodium nickel-manganese sulfate, Na2Ni1/2Mn1/2(SO4)2, having a large monoclinic unit cell, through electrochemical and ex situ diffraction and spectroscopic methods. The sulfate salt Na2Ni1/2Mn1/2(SO4)2 is prepared by thermal dehydration of the corresponding hydrate salt Na2Ni1/2Mn1/2(SO4)2·4H2O having a blödite structure. The intercalation reactions on Na2Ni1-xMnx(SO4)2 are studied in two model cells: half-ion cell versus Li metal anode and full-ion cell versus Li4Ti5O12 anode by using lithium (LiPF6 dissolved in EC/DMC) and sodium electrolytes (NaPF6 dissolved in EC:DEC). Based on ex situ XRD and TEM analysis, it is found that sodium intercalation into Na2Ni1/2Mn1/2(SO4)2 takes place via phase separation into the Ni-rich monoclinic phase and Mn-rich alluaudite phase. The redox reactions involving participation of manganese and titanium ions are monitored by ex situ EPR spectroscopy. It has been demonstrated that manganese ions from the sulfate salt are participating in the electrochemical reaction, while the nickel ions remain intact. As a result, a reversible capacity of about 65 mA h g-1 is reached. The selective intercalation properties determine sodium nickel-manganese sulfate as a new electrode material for hybrid lithium-sodium ion batteries that is thought to combine the advantages of individual lithium and sodium batteries.

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.

Non-aqueous electrolyte for high voltage rechargeable magnesium batteries

DOEpatents

Doe, Robert Ellis; Lane, George Hamilton; Jilek, Robert E; Hwang, Jaehee

2015-02-10

An electrolyte for use in electrochemical cells is provided. The properties of the electrolyte include high conductivity, high Coulombic efficiency, and an electrochemical window that can exceed 3.5 V vs. Mg/Mg.sup.+2. The use of the electrolyte promotes the electrochemical deposition and dissolution of Mg without the use of any Grignard reagents, other organometallic materials, tetraphenyl borate, or tetrachloroaluminate derived anions. Other Mg-containing electrolyte systems that are expected to be suitable for use in secondary batteries are also described.

Electrochemical monitoring of malondialdehyde biomarker in biological samples via electropolymerized amino acid/chitosan nanocomposite.

PubMed

Hasanzadeh, Mohammad; Mokhtari, Fozieh; Jouyban-Gharamaleki, Vahid; Mokhtarzadeh, Ahad; Shadjou, Nasrin

2018-04-15

This study reports on the electropolymerization of a low toxic and biocompatible nanopolymer with entitle poly arginine-graphene quantum dots-chitosan (PARG-GQDs-CS) as a novel strategy for surface modification of glassy carbon surface and preparation of a new interface for measurement of malondialdehyde (MDA) in exhaled breath condensate. Electrochemical deposition, as a well-controlled synthesis procedure, has been used for subsequently layer-by-layer preparation of GQDs-CS nanostructures on a PARG prepolymerized on the surface of glassy carbon electrode using cyclic voltammetry techniques in the regime of -1.5 to 2 V. The modified electrode appeared as an effective electroactivity for detection of MDA by using cyclic voltammetry, linear sweep voltammetry, and differential pulse voltammetry. The prepared modified electrode demonstrated a noticeably good activity for electrooxidation of MDA than PARG. Enhancement of peak currents is ascribed to the fast heterogeneous electron transfer kinetics that arise from the synergistic coupling between the excellent properties of PARG and semiconducting polymer, GQDs as high density of edge plane sites and subtle electronic characteristics and unique properties of CS such as excellent film-forming ability, high permeability, good adhesion, nontoxicity, cheapness, and a susceptibility to chemical modification. The prepared sensor showed 1 oxidation processes for MDA at potentials about 1 V with a low limit of quantification 5.94 nM. Finally, application of new sensor for determination of MDA in exhaled breath condensate was suited. In general, the simultaneous attachment of GQDs and CS to structure of poly amino acids provides new opportunities within the personal healthcare. Copyright © 2018 John Wiley & Sons, Ltd.

One-pot preparation of PEDOT:PSS-reduced graphene decorated with Au nanoparticles for enzymatic electrochemical sensing of H2O2

NASA Astrophysics Data System (ADS)

Mercante, Luiza A.; Facure, Murilo H. M.; Sanfelice, Rafaela C.; Migliorini, Fernanda L.; Mattoso, Luiz H. C.; Correa, Daniel S.

2017-06-01

The development of novel graphene-based nanocomposites is a hotspot in materials science due to their unique optical, electronic, thermal, mechanical and catalytic properties for varied applications. The present work reports on the development of a graphene-based ternary nanocomposite of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), reduced graphene oxide and gold nanoparticles (PEDOT:PSS-rGO-AuNPs) for the detection of hydrogen peroxide (H2O2). The hybrid nanocomposite showed superior electrochemical properties and higher stability compared to each individual component as electrode materials, showing a synergistic effect between PEDOT, rGO and AuNPs. The nanocomposite was obtained via a facile one-step approach and was assembly with horseradish peroxidase (HRP). The PEDOT:PSS-rGO-AuNPs-HRP modified electrode has been used for the amperometric detection of H2O2 and exhibited a high sensitivity of up to 677 μA mM-1 cm-2, with a wide linear range from 5 to 400 μM and a low detection limit of 0.08 μM (S/N = 3). This developed enzymatic biosensor showed to be highly stable and unresponsive to potentially interfering substances, and it could be used for sensing H2O2 in real samples, including tap water and bovine milk samples. These enhanced sensing performance could be ascribed to the intimate contact of AuNPs onto the rough surface of the PEDOT:PSS-rGO nanocomposite, which has a high electrical conductivity and large surface area, providing it as an excellent substrate for the growth and support of nanoparticles. The method developed in this work opens up a general route to prepare a wide range of graphene-based hybrid nanocomposite films with multiple functions including sensing and biosensing.

Multilayer ZnO/Pd/ZnO Structure as Sensing Membrane for Extended-Gate Field-Effect Transistor (EGFET) with High pH Sensitivity

NASA Astrophysics Data System (ADS)

Rasheed, Hiba S.; Ahmed, Naser M.; Matjafri, M. Z.; Al-Hardan, Naif H.; Almessiere, Munirah Abdullah; Sabah, Fayroz A.; Al-Hazeem, Nabeel Z.

2017-10-01

Metal oxide nanostructures have attracted considerable attention as pH-sensitive membranes because of their unique advantages. Specifically, the special properties of ZnO thin film, including high surface-to-volume ratio, nontoxicity, thermal stability, chemical stability, electrochemical activity, and high mechanical strength, have attracted massive interest. ZnO exhibits wide bandgap of 3.37 eV, good biocompatibility, high reactivity, robustness, and environmental stability. These unique properties explain why ZnO has the most applications among all nanostructured metal oxides based on its structure and properties. Moreover, ZnO has excellent electrical characteristics, enabling its use in accurate sensors with rapid response. ZnO nanostructures can be used in novel pH and biomedical sensing applications. However, ZnO thin film exhibits large sheet resistance and low conductivity. Increasing the conductivity or reducing the resistivity of ZnO sensing membranes is important to achieve low impedance. We propose herein a new design using a multilayer ZnO/Pd/ZnO structure as a pH-sensing membrane. Multiple layers were deposited by radio frequency (RF) sputtering for ZnO and direct current (DC) sputtering for Pd to achieve low sheet resistance. These multilayers with low sheet resistance of 15.8 Ω/sq were then successfully used to control the conductivity in extended-gate field-effect transistors (EGFETs). The resulting multilayered EGFET pH-sensor demonstrated improved sensing performance. The measured sensitivity of the pH sensor was 40 μA/pH and 52 mV/pH within the pH range from 2 to 12, rendering this structure suitable for use in various applications, including pH sensors and biosensors.

Theoretical Investigations of the Electrochemical Reduction of CO on Single Metal Atoms Embedded in Graphene

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

Kirk, Charlotte; Chen, Leanne D.; Siahrostami, Samira

Single transition metal atoms embedded at single vacancies of graphene provide a unique paradigm for catalytic reactions. We present a density functional theory study of such systems for the electrochemical reduction of CO. Theoretical investigations of CO electrochemical reduction are particularly challenging in that electrochemical activation energies are a necessary descriptor of activity. We determined the electrochemical barriers for key proton–electron transfer steps using a state-of-the-art, fully explicit solvent model of the electrochemical interface. The accuracy of GGA-level functionals in describing these systems was also benchmarked against hybrid methods. We find the first proton transfer to form CHO from COmore » to be a critical step in C 1 product formation. On these single atom sites, the corresponding barrier scales more favorably with the CO binding energy than for 211 and 111 transition metal surfaces, in the direction of improved activity. Intermediates and transition states for the hydrogen evolution reaction were found to be less stable than those on transition metals, suggesting a higher selectivity for CO reduction. We present a rate volcano for the production of methane from CO. We identify promising candidates with high activity, stability, and selectivity for the reduction of CO. As a result, this work highlights the potential of these systems as improved electrocatalysts over pure transition metals for CO reduction.« less

Theoretical Investigations of the Electrochemical Reduction of CO on Single Metal Atoms Embedded in Graphene

DOE PAGES

Kirk, Charlotte; Chen, Leanne D.; Siahrostami, Samira; ...

2017-12-18

Single transition metal atoms embedded at single vacancies of graphene provide a unique paradigm for catalytic reactions. We present a density functional theory study of such systems for the electrochemical reduction of CO. Theoretical investigations of CO electrochemical reduction are particularly challenging in that electrochemical activation energies are a necessary descriptor of activity. We determined the electrochemical barriers for key proton–electron transfer steps using a state-of-the-art, fully explicit solvent model of the electrochemical interface. The accuracy of GGA-level functionals in describing these systems was also benchmarked against hybrid methods. We find the first proton transfer to form CHO from COmore » to be a critical step in C 1 product formation. On these single atom sites, the corresponding barrier scales more favorably with the CO binding energy than for 211 and 111 transition metal surfaces, in the direction of improved activity. Intermediates and transition states for the hydrogen evolution reaction were found to be less stable than those on transition metals, suggesting a higher selectivity for CO reduction. We present a rate volcano for the production of methane from CO. We identify promising candidates with high activity, stability, and selectivity for the reduction of CO. As a result, this work highlights the potential of these systems as improved electrocatalysts over pure transition metals for CO reduction.« less

Nanoarchitectures for Metal-Organic Framework-Derived Nanoporous Carbons toward Supercapacitor Applications.

PubMed

Salunkhe, Rahul R; Kaneti, Yusuf Valentino; Kim, Jeonghun; Kim, Jung Ho; Yamauchi, Yusuke

2016-12-20

The future advances of supercapacitors depend on the development of novel carbon materials with optimized porous structures, high surface area, high conductivity, and high electrochemical stability. Traditionally, nanoporous carbons (NPCs) have been prepared by a variety of methods, such as templated synthesis, carbonization of polymer precursors, physical and chemical activation, etc. Inorganic solid materials such as mesoporous silica and zeolites have been successfully utilized as templates to prepare NPCs. However, the hard-templating methods typically involve several synthetic steps, such as preparation of the original templates, formation of carbon frameworks, and removal of the original templates. Therefore, these methods are not favorable for large-scale production. Metal-organic frameworks (MOFs) with high surface areas and large pore volumes have been studied over the years, and recently, enormous efforts have been made to utilize MOFs for electrochemical applications. However, their low conductivity and poor stability still present major challenges toward their practical applications in supercapacitors. MOFs can be used as precursors for the preparation of NPCs with high porosity. Their parent MOFs can be prepared with endless combinations of organic and inorganic constituents by simple coordination chemistry, and it is possible to control their porous architectures, pore volumes, surface areas, etc. These unique properties of MOF-derived NPCs make them highly attractive for many technological applications. Compared with carbonaceous materials prepared using conventional precursors, MOF-derived carbons have significant advantages in terms of a simple synthesis with inherent diversity affording precise control over porous architectures, pore volumes, and surface areas. In this Account, we will summarize our recent research developments on the preparation of three-dimensional (3-D) MOF-derived carbons for supercapacitor applications. This Account will be divided into three main sections: (1) useful background on carbon materials for supercapacitor applications, (2) the importance of MOF-derived carbons, and (3) potential future developments of MOF-derived carbons for supercapacitors. This Account focuses mostly on carbons derived from two types of MOFs, namely, zeolite imidazolate framework-8 (ZIF-8) and ZIF-67. By using examples from our previous works, we will show the uniqueness of these carbons for achieving high performance by control of the chemical reactions/conditions as well proper utilization in asymmetric/symmetric supercapacitor configurations. This Account will promote further developments of MOF-derived multifunctional carbon materials with controlled porous architectures for optimization of their electrochemical performance toward supercapacitor applications.

Performance of solid state supercapacitors based on polymer electrolytes containing different ionic liquids

NASA Astrophysics Data System (ADS)

Tiruye, Girum Ayalneh; Muñoz-Torrero, David; Palma, Jesus; Anderson, Marc; Marcilla, Rebeca

2016-09-01

Four Ionic Liquid based Polymer Electrolytes (IL-b-PE) were prepared by blending a Polymeric Ionic Liquid, Poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PILTFSI), with four different ionic liquids: 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) (IL-b-PE1), 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide (PYR14FSI) (IL-b-PE2), 1-(2-hydroxy ethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (HEMimTFSI) (IL-b-PE3), and 1-Butyl-1-methylpyrrolidinium dicyanamide, (PYR14DCA) (IL-b-PE4). Physicochemical properties of IL-b-PE such as ionic conductivity, thermal and electrochemical stability were found to be dependent on the IL properties. For instance, ionic conductivity was significantly higher for IL-b-PE2 and IL-b-PE4 containing IL with small size anions (FSI and DCA) than IL-b-PE1 and IL-b-PE3 bearing IL with bigger anion (TFSI). On the other hand, wider electrochemical stability window (ESW) was found for IL-b-PE1 and IL-b-PE2 having ILs with electrochemically stable pyrrolidinium cation and FSI and TFSI anions. Solid state Supercapacitors (SCs) were assembled with activated carbon electrodes and their electrochemical performance was correlated with the polymer electrolyte properties. Best performance was obtained with SC having IL-b-PE2 that exhibited a good compromise between ionic conductivity and electrochemical window. Specific capacitance (Cam), real energy (Ereal) & real power densities (Preal) as high as 150 F g-1, 36 Wh kg-1 & 1170 W kg-1 were found at operating voltage of 3.5 V.

Nanostructured Metal Oxide Coatings for Electrochemical Energy Conversion and Storage Electrodes

NASA Astrophysics Data System (ADS)

Cordova, Isvar Abraxas

The realization of an energy future based on safe, clean, sustainable, and economically viable technologies is one of the grand challenges facing modern society. Electrochemical energy technologies underpin the potential success of this effort to divert energy sources away from fossil fuels, whether one considers alternative energy conversion strategies through photoelectrochemical (PEC) production of chemical fuels or fuel cells run with sustainable hydrogen, or energy storage strategies, such as in batteries and supercapacitors. This dissertation builds on recent advances in nanomaterials design, synthesis, and characterization to develop novel electrodes that can electrochemically convert and store energy. Chapter 2 of this dissertation focuses on refining the properties of TiO2-based PEC water-splitting photoanodes used for the direct electrochemical conversion of solar energy into hydrogen fuel. The approach utilized atomic layer deposition (ALD); a growth process uniquely suited for the conformal and uniform deposition of thin films with angstrom-level thickness precision. ALD's thickness control enabled a better understanding of how the effects of nitrogen doping via NH3 annealing treatments, used to reduce TiO2's bandgap, can have a strong dependence on TiO2's thickness and crystalline quality. In addition, it was found that some of the negative effects on the PEC performance typically associated with N-doped TiO2 could be mitigated if the NH 3-annealing was directly preceded by an air-annealing step, especially for ultrathin (i.e., < 10 nm) TiO2 films. ALD was also used to conformally coat an ultraporous conductive fluorine-doped tin oxide nanoparticle (nanoFTO) scaffold with an ultrathin layer of TiO2. The integration of these ultrathin films and the oxide nanoparticles resulted in a heteronanostructure design with excellent PEC water oxidation photocurrents (0.7 mA/cm2 at 0 V vs. Ag/AgCl) and charge transfer efficiency. In Chapter 3, two innovative nanoarchitectures were engineered in order to enhance the pseudocapacitive energy storage of next generation supercapacitor electrodes. The morphology and quantity of MnO2 electrodeposits was controlled by adjusting the density of graphene foliates on a novel graphenated carbon nanotube (g-CNT) scaffold. This control enabled the nanocomposite supercapacitor electrode to reach a capacitance of 640 F/g, under MnO2 specific mass loading conditions (2.3 mg/cm2) that are higher than previously reported. In the second engineered nanoarchitecture, the electrochemical energy storage properties of a transparent electrode based on a network of solution-processed Cu/Ni cores/shell nanowires (NWs) were activated by electrochemically converting the Ni metal shell into Ni(OH)2. Furthermore, an adjustment of the molar percentage of Ni plated onto the Cu NWs was found to result in a tradeoff between capacitance, transmittance, and stability of the resulting nickel hydroxide-based electrode. The nominal area capacitance and power performance results obtained for this Cu/Ni(OH)2 transparent electrode demonstrates that it has significant potential as a hybrid supercapacitor electrode for integration into cutting edge flexible and transparent electronic devices.

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.

Electrochemical studies on nanometal oxide-activated carbon composite electrodes for aqueous supercapacitors

NASA Astrophysics Data System (ADS)

Ho, Mui Yen; Khiew, Poi Sim; Isa, Dino; Chiu, Wee Siong

2014-11-01

In present study, the electrochemical performance of eco-friendly and cost-effective titanium oxide (TiO2)-based and zinc oxide-based nanocomposite electrodes were studied in neutral aqueous Na2SO3 electrolyte, respectively. The electrochemical properties of these composite electrodes were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS). The experimental results reveal that these two nanocomposite electrodes achieve the highest specific capacitance at fairly low oxide loading onto activated carbon (AC) electrodes, respectively. Considerable enhancement of the electrochemical properties of TiO2/AC and ZnO/AC nanocomposite electrodes is achieved via synergistic effects contributed from the nanostructured metal oxides and the high surface area mesoporous AC. Cations and anions from metal oxides and aqueous electrolyte such as Ti4+, Zn2+, Na+ and SO32- can occupy some pores within the high-surface-area AC electrodes, forming the electric double layer at the electrode-electrolyte interface. Additionally, both TiO2 and ZnO nanoparticles can provide favourable surface adsorption sites for SO32- anions which subsequently facilitate the faradaic processes for pseudocapacitive effect. These two systems provide the low cost material electrodes and the low environmental impact electrolyte which offer the increased charge storage without compromising charge storage kinetics.

Corrosion of NiTi Wires with Cracked Oxide Layer

NASA Astrophysics Data System (ADS)

Racek, Jan; Šittner, Petr; Heller, Luděk; Pilch, Jan; Petrenec, Martin; Sedlák, Petr

2014-07-01

Corrosion behavior of superelastic NiTi shape memory alloy wires with cracked TiO2 surface oxide layers was investigated by electrochemical corrosion tests (Electrochemical Impedance Spectroscopy, Open Circuit Potential, and Potentiodynamic Polarization) on wires bent into U-shapes of various bending radii. Cracks within the oxide on the surface of the bent wires were observed by FIB-SEM and TEM methods. The density and width of the surface oxide cracks dramatically increase with decreasing bending radius. The results of electrochemical experiments consistently show that corrosion properties of NiTi wires with cracked oxide layers (static load keeps the cracks opened) are inferior compared to the corrosion properties of the straight NiTi wires covered by virgin uncracked oxides. Out of the three methods employed, the Electrochemical Impedance Spectroscopy seems to be the most appropriate test for the electrochemical characterization of the cracked oxide layers, since the impedance curves (Nyquist plot) of differently bent NiTi wires can be associated with increasing state of the surface cracking and since the NiTi wires are exposed to similar conditions as the surfaces of NiTi implants in human body. On the other hand, the potentiodynamic polarization test accelerates the corrosion processes and provides clear evidence that the corrosion resistance of bent superelastic NiTi wires degrades with oxide cracking.

Engineering the electrochemical capacitive properties of graphene sheets in ionic-liquid electrolytes by correct selection of anions.

PubMed

Shi, Minjie; Kou, Shengzhong; Yan, Xingbin

2014-11-01

Graphene sheet (GS)-ionic liquid (IL) supercapacitors are receiving intense interest because their specific energy density far exceeds that of GS-aqueous electrolytes supercapacitors. The electrochemical properties of ILs mainly depend on their diverse ions, especially anions. Therefore, identifying suitable IL electrolytes for GSs is currently one of the most important tasks. The electrochemical behavior of GSs in a series of ILs composed of 1-ethyl-3-methylimidazolium cation (EMIM(+)) with different anions is systematically studied. Combined with the formula derivation and building models, it is shown that the viscosity, ion size, and molecular weight of ILs affect the electrical conductivity of ILs, and thus, determine the electrochemical performances of GSs. Because the EMIM-dicyanamide IL has the lowest viscosity, ion size, and molecular weight, GSs in it exhibit the highest specific capacitance, smallest resistance, and best rate capability. In addition, because the tetrafluoroborate anion (BF4(-)) has the best electrochemical stability, the GS-[EMIM][BF4] supercapacitor has the widest potential window, and thus, displays the largest energy density. These results may provide valuable information for selecting appropriate ILs and designing high-performance GS-IL supercapacitors to meet different needs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Development of Non-Enzymatic Glucose Biosensors Based on Electrochemically Prepared Polypyrrole-Chitosan-Titanium Dioxide Nanocomposite Films.

PubMed

Al-Mokaram, Ali M A Abdul Amir; Yahya, Rosiyah; Abdi, Mahnaz M; Mahmud, Habibun Nabi Muhammad Ekramul

2017-05-31

The performance of a modified electrode of nanocomposite films consisting of polypyrrole-chitosan-titanium dioxide (Ppy-CS-TiO₂) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO₂ nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO₂ NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO₂ in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1-14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO₂ nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell.

Effect of chemical treatment on the electrochemical properties of Li1.2NixMn0.8-xO2 (x = 0.2 and 0.25) in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Konishi, Hiroaki; Hirano, Tatsumi; Takamatsu, Daiko; Gunji, Akira; Feng, Xiaoliang; Furutsuki, Sho; Okumura, Takefumi; Terada, Shohei

2018-02-01

The effect of chemical treatment using (NH4)2SO4 on the electrochemical properties of Li1.2Ni0.2Mn0.6O2 and Li1.2Ni0.25Mn0.55O2 was investigated. The treatment was effective in improving the Coulombic efficiency and discharge capacity of a Li1.2Ni0.2Mn0.6O2 cathode, but treatment with too much (NH4)2SO4 degraded the cathode's electrochemical performance. The effect of (NH4)2SO4 treatment on the charge-discharge reaction mechanism of Li1.2Ni0.2Mn0.6O2 was investigated by evaluating reaction potential, particle configuration, and oxidation state of transition metal. The experimental results indicated that the changes in the electrochemical performance of the treated cathodes were attributed to the changes in the surface state and of the element contributing to the redox reaction. Treatment with an appropriate amount of (NH4)2SO4 also improved the electrochemical performance of the high-nickel-content lithium-rich layer-structured cathode material Li1.2Ni0.25Mn0.55O2.

Electrochemical properties and electrocatalytic activity of conducting polymer/copper nanoparticles supported on reduced graphene oxide composite

NASA Astrophysics Data System (ADS)

Ehsani, Ali; Jaleh, Babak; Nasrollahzadeh, Mahmoud

2014-07-01

Reduced graphene oxide (rGO) was used to support Cu nanoparticles. As electro-active electrodes for supercapacitors composites of reduced graphene oxide/Cu nanoparticles (rGO/CuNPs) and polytyramine (PT) with good uniformity are prepared by electropolymerization. Composite of rGO/CuNPs-PT was synthesized by cyclic voltammetry (CV) methods and electrochemical properties of film were investigated by using electrochemical techniques. The results show that, the rGO/CuNPs-PT/G has better capacitance performance. This is mainly because of the really large surface area and the better electronic and ionic conductivity of rGO/CuNPs-PT/G, which lead to greater double-layer capacitance and faradic pseudo capacitance. Modified graphite electrodes (rGO/CuNPs-PT/G) were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) were employed. In comparison with a Cu-PT/G (Graphite), rGO/CuNPs-PT/G modified electrode shows a significantly higher response for methanol oxidation. A mechanism based on the electro-chemical generation of Cu(III) active sites and their subsequent consumptions by methanol have been discussed.

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.

Self-healing effect of the protective inhibitor-containing coatings on Mg alloys

NASA Astrophysics Data System (ADS)

Gnedenkov, A. S.; Sinebryukhov, S. L.; Mashtalyar, D. V.; Gnedenkov, S. V.

2017-09-01

The method of self-healing coating formation on the surface of magnesium alloys on the base of plasma electrolytic oxidation (PEO) with subsequent impregnation of the obtained layer with inhibitor has been suggested. The protective and electrochemical properties of such coatings have been described. Localised Scanning Electrochemical Methods were used for determining the kinetics and mechanism of the self-healing process. The treatment with the solution containing inhibitor enables us to increase the protective properties of the PEO-coating in 30 times in the corrosion-active environment.

Determination of the Effect of Composition, Structure and Electrochemical Mass Transport Properties on Adhesion and Corrosion Inhibition of Paint Films.

DTIC Science & Technology

1981-10-01

Stirring speeds of approximately 100 rpm were achieved with a magnetic stir plate. The assembled Hittorf cell was placed in a Faraday cage during experiments...P AO-A113 975 ELECTROCNCNICAL TECHNOLOGY CORP SEATTLE WA F/6 11/3 DETERMINATION OF THE EFFECT OF COMPOSITION, STRUCTURE AND 4IECT--ETC(U) OCT 81 R T...ElllllEEllEEEI I! Contract No. N00014-79-C-0021 DETERMINATION OF THE EFFECT OF COMPOSITION, STRUCTURE AND ELECTROCHEMICAL MASS TRANSPORT PROPERTIES ON ADHESION

Photophysical, electrochemical, thermal and aggregation properties of new metal phthalocyanines

NASA Astrophysics Data System (ADS)

Jeong, Jaemyeng; Kumar, Rangaraju Satish; Mergu, Naveen; Son, Young-A.

2017-11-01

In this study, the synthesis of di(ethylene glycol) naphthalene substituted metal-phthalocyanines was reported. These novel phthalocyanines were characterized by elemental and spectroscopic analysis, including 1H NMR, FT-IR, UV-Vis spectral and MALDI-TOF mass data. The aggregation behavior of these phthalocyanines was examined in chloroform at different concentrations, and we confirmed that the phthalocyanines were non-aggregated. Further thermal stability, electrochemical, theoretical studies and metal sensing properties also investigated. In addition, we successfully prepared phthalocyanine (6d) blended polyurethane electrospun (ES) nanofibers.

Engineering hierarchical Diatom@CuO@MnO2 hybrid for high performance supercapacitor

NASA Astrophysics Data System (ADS)

Zhang, Yan; Guo, Wan Wan; Zheng, Tian Xu; Zhang, Yu Xin; Fan, Xing

2018-01-01

A rational and hierarchical Diatom@CuO@MnO2 hybrid was fabricated via a facile electroless copper plating technology, following by a one-pot hydrothermal reaction with KMnO4. Such unique architecture acts as a supercapacitor electrode, which exhibits a high specific capacitance (240 F g-1 at a current density of 0.5 A g-1), good rate capability (58.3% retention when the current density increases from 0.5 to 5 A g-1), and excellent electrochemical cycling stability (91.2% retention of the initial specific capacitance after 4000 cycles at a current density of 2 A g-1). The impressive electrochemical performance of this Diatom@CuO@MnO2 electrode ascribed to the synergistic effect between the CuO particles and MnO2 nanosheets. Therefore, it can be expected that this unique Diatom@CuO@MnO2 electrode may have great promise for the application in supercapacitors.

Nanoporous platinum-cobalt alloy for electrochemical sensing for ethanol, hydrogen peroxide, and glucose.

PubMed

Xu, Caixia; Sun, Fenglei; Gao, Hua; Wang, Jinping

2013-05-30

Nanoporous platinum-cobalt (NP-PtCo) alloy with hierarchical nanostructure is straightforwardly fabricated by dealloying PtCoAl alloy in a mild alkaline solution. Selectively etching Al resulted in a hierarchical three-dimensional network nanostructure with a narrow size distribution at 3 nm. The as-prepared NP-PtCo alloy shows superior performance toward ethanol and hydrogen peroxide (H2O2) with highly sensitive response due to its unique electrocatalytic activity. In addition, NP-PtCo also exhibits excellent amperometric durability and long-term stability for H2O2 as well as a good anti-interference toward ascorbic acid, uric acid, and dopamine. The hierarchical nanoporous architecture in PtCo alloy is also highly active for glucose sensing electrooxidation and sensing in a wide linear range. The NP-PtCo alloy holds great application potential for electrochemical sensing with simple preparation, unique catalytic activity, and high structure stability. Copyright © 2013 Elsevier B.V. All rights reserved.

Bubble template synthesis of hollow gold nanoparticles and their applications as theranostic agents

NASA Astrophysics Data System (ADS)

Huang, Chienwen

Hollow gold nanoparticle with a sub-30nm polycrystalline shell and a 50 nm hollow core has been successfully synthesized through the reduction of sodium gold sulfite by electrochemically evolved hydrogen. Such hollow gold nanoparticles exhibit unique plasmonic properties. They strongly scatter and absorb near infrared light. In this thesis we seek to understand the formation mechanism of hollow gold nanoparticles in this new synthesis process and their plasmonic properties. Also, we explore their biomedical applications as theranostic agents (therapeutic and diagnostic imaging). A lithographically patterned electrode consisting of Ag stripes on a glass substrate was used to investigate the formation process of hollow gold nanoparticles. Ag stripes served as working electrode for electrochemically evolution of hydrogen, and adjacent glass areas provided supporting surface for hydrogen nanobubbles nucleation and growth. Hydrogen nanobubbles served as both templates and reducing agents to trigger the autocatalytic disproportionation reaction of sodium gold sulfite. The effects of applied potential and the additives in the electrolyte have been studied. It has been found that the size and size distribution of hollow gold nanoparticle are directly relative to the applied potential, i.e. the hydrogen evolution rate. It has also been found the addition of Ni2+ ions can greatly improve the size distribution of hollow gold nanoparticles that can be contributed to that the newly electrodeposited nickel metal can enhance the hydrogen evolution efficiency. Another additive, ethylenediamine (EDA) can suppress the autocatalytic reaction of gold sulfite to increase the stability of sodium gold sulfite electrolyte. To capture such electrochemically evolved hydrogen nanobubbles, and subsequently to generate hollow gold nanoparticles in large numbers, alumina membranes were placed on the top of the working electrode. Anodic alumina membrane consists of ~200 nm pores, which provides a large surface area for the formation of hydrogen nanobubbles. By this approach, the electroless reaction can be easily separated from the electrodeposition process, and hollow gold nanoparticles can be easily collected. Synthesized hollow gold nanoparticles exhibit unique plasmonic properties; the surface plasmon resonance (SPR) lies in the near infrared region (NIR). This is very different from the solid spherical gold nanoparticles. Three-dimensional finite difference time domain (FDTD) simulation was employed to study the plasmonic properties of hollow gold nanoparticles. It has been found that the red-shifts of SPR peaks are mainly caused by their surface roughness, and the hollow nature of these particles only plays a minor role. The surface roughness of hollow gold nanoparticles can be tuned by adjusting the pH of the electrolyte (from 6.0 to 7.0) by adding sodium sulfite. Different surface roughness (from smooth to very rough) can be readily obtained, and correspondingly, surface plasmon resonance (SPR) peaks red-shift from ~600 nm to ~750 nm. Using hollow gold nanoparticles as multifunctional agents for biomedical applications have been explored. Two kinds of agents have been constructed. It has been demonstrated that pegylated Raman dye encoded hollow gold nanoparticles, terms as Raman nanotags, can serve as both diagnostic imaging agents and photothermal therapy agents. When illuminated by near infrared light, the enhanced Raman signal makes the hollow gold nanoparticles to become optically detectable for biomedical imaging, and absorbed light rapidly heat up the hollow gold nanoparticles which can be used to photothermal ablation therapy. The cytotoxicity evaluation using [3H] thymidine incorporation method has shown non-toxicity of the Raman nanotags. The photothermal effects of hollow gold nanoparticles have been examined by two methods: (1) by embedding hollow gold nanoparticles in tissue-like phantom environment; (2) by recording infrared images as temperature increase. The results show that hollow gold nanoparticles are capable to generate sufficiency heat for photothermal therapy. To fully take advantage of the unique hollow core space of hollow gold nanoparticles, a facile route has been develop to trap Fe3O4 nanoparticles into the hollow gold nanoparticles to form Fe3O4/Au core/shell nanoparticles. Fe3O4/Au core/shell nanoparticles possess the desirable magnetic and plasmonic properties that can be used as magnetic resonance contrast (MRI) agents and photothermal therapy agents.

Interfacial characterization and supercapacitive properties of polyaniline-Gum arabic nanocomposite/graphene oxide LbL modified electrodes

NASA Astrophysics Data System (ADS)

Oliveira, Rafaela D.; Santos, Cleverson S.; Ferreira, Rodolfo T.; Marciniuk, Gustavo; Marchesi, Luís F.; Garcia, Jarem R.; Vidotti, Marcio; Pessoa, Christiana A.

2017-12-01

In this manuscript, we describe the synthesis and electrochemical characterization of polyaniline-gum arabic nanocomposites and graphene oxide (PANI-GA/GO) modified electrodes with a detailed study concerning their supercapacitive properties. The electrode modification was carried out by using the Layer-by-Layer technique (LbL), where the PANI-GA nanocomposite dispersion was used as polycation and the GO colloidal dispersion as polyanion. The bilayer growth was followed by both UV-vis spectroscopy and cyclic voltammetry, and an increase in the characteristic PANI absorption and in the electrochemical signal was verified, confirming the electrode build up. Galvanostatic charge-discharge curves (GCDC) were performed to evaluate the supercapacitive properties of the modified electrodes, these results showed the dependence of the specific capacitance with the number of bilayers, where values of CS around 15 mF cm-2 (i = 0.1 mA cm-2) were found. Electrochemical impedance spectroscopy confirmed the pseudocapacitive properties of the modified electrodes, showing an increase in the low-frequency capacitance with the number of bilayers. Hereby the (PANI-GA/GO)-LbL electrodes were shown to be good candidates for active materials in supercapacitors.

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.

High performance supercapacitor from activated carbon derived from waste orange skin

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Hussain, S.; Ahmed, Ahsan; Rafat, M.

2018-05-01

Activated carbon due to its inherent properties such as large surface area and low cost is most frequently used electrode material for supercapacitor. Activated carbon has been previously derived from various biomass such as coconut shell, coffee bean etc. Herein, we report the synthesis of activated carbon from waste orange skin. The material was synthesized employing chemical activation method and the success of synthesis was confirmed by its physical and electrochemical properties. The physical properties of the as-prepared sample were studied using the techniques of XRD, SEM, Raman spectroscopy and N2 adsorption/desorption analysis while its electrochemical properties were studied in two-electrode assembly using liquid electrolyte (consisting of 1 M solution of LiTFSI dispersed in ionic liquid EMITFSI) and employing the techniques of cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge- discharge. The synthesized sample of activated carbon exhibits high specific capacitance of 115 F g-1 at 10 mV s-1. Also, the activated carbon electrode shows the retention of ˜75% in initial capacitance value for more than 2000 initial cycles, indicating the as-prepared activated carbon can be profitably used as electrode material for energy storage devices.

Electrochemical Properties of Poly(Anthraquinonyl Sulfide)/Graphene Sheets Composites as Electrode Materials for Electrochemical Capacitors

PubMed Central

Lee, Wonkyun; Suzuki, Shinya; Miyayama, Masaru

2014-01-01

Poly(anthraquinonyl sulfide) (PAQS)/graphene sheets (GSs) composite was synthesized through in situ polymerization to evaluate its performance as an electrode material for electrochemical capacitors. PAQS was successfully synthesized in the presence of GSs with uniform distribution. PAQS/GSs showed a pair of reversible redox peaks at around 0 V (vs. Ag/AgCl). The specific capacitance of PAQS/GSs was 349 F·g−1 (86 mAh·g−1) at a current density of 500 mA·g−1, and a capacitance of 305 F·g−1 was maintained even at a high current density of 5000 mA·g−1. The in situ polymerization of PAQS with GSs facilitated their interaction and enabled faster charge transfer and redox reaction, resulting in enhanced electrode properties. PMID:28344238

Highly sensitive and selective electrochemical dopamine sensing properties of multilayer graphene nanobelts

NASA Astrophysics Data System (ADS)

Karthick Kannan, Padmanathan; Moshkalev, Stanislav A.; Sekhar Rout, Chandra

2016-02-01

In the present study, we report the electrochemical sensing property of multi-layer graphene nanobelts (GNBs) towards dopamine (DA). GNBs are synthesized from natural graphite and characterized by using techniques like field-emission scanning electron microscopy, atomic force microscopy and Raman spectroscopy. An electrochemical sensor based on GNBs is developed for the detection of DA. From the cyclic voltammetry and amperometry studies, it is found that GNBs possess excellent electrocatalytic activity towards DA molecules. The developed DA sensor showed a sensitivity value of 0.95 μA μM-1 cm-2 with a linear range of 2 μM to 0.2 mM. The interference data exhibited that GNB is highly selective to DA even in the presence of common interfering species like ascorbic acid, uric acid, glucose and lactic acid.

Highly sensitive and selective electrochemical dopamine sensing properties of multilayer graphene nanobelts.

PubMed

Kannan, Padmanathan Karthick; Moshkalev, Stanislav A; Rout, Chandra Sekhar

2016-02-19

In the present study, we report the electrochemical sensing property of multi-layer graphene nanobelts (GNBs) towards dopamine (DA). GNBs are synthesized from natural graphite and characterized by using techniques like field-emission scanning electron microscopy, atomic force microscopy and Raman spectroscopy. An electrochemical sensor based on GNBs is developed for the detection of DA. From the cyclic voltammetry and amperometry studies, it is found that GNBs possess excellent electrocatalytic activity towards DA molecules. The developed DA sensor showed a sensitivity value of 0.95 μA μM(-1) cm(-2) with a linear range of 2 μM to 0.2 mM. The interference data exhibited that GNB is highly selective to DA even in the presence of common interfering species like ascorbic acid, uric acid, glucose and lactic acid.

Gold-carbon composite thin films for electrochemical gas sensor prepared by reactive plasma sputtering

NASA Astrophysics Data System (ADS)

Okamoto, A.; Suzuki, Y.; Yoshitake, M.; Ogawa, S.; Nakano, N.

1997-01-01

We have investigated the properties of gold-carbon composite thin films prepared by a plasma sputtering deposition using argon and methane mixture gas. These composite films have an uneven surface in submicron scale or consist of nano-scale particles of gold polycrystalline. Such morphological properties can be controlled by the sputtering voltage and the partial pressure of methane gas. The working electrode of electrochemical gas sensor has needed a stable gas sensitivity and a good gas selectivity. Our composite film is one of the excellent candidates for a thin film working electrode of electrochemical gas sensor. It is described that the output current of sensor is related to the preparation conditions of the thin films and increase linearly as the concentration of PH 3 gas ranging from 0.1 to 1.0 ppm is increasing.

Core-Shell PdPb@Pd Aerogels with Multiply-Twinned Intermetallic Nanostructures: Facile Synthesis with Accelerated Gelation Kinetics and Their Enhanced Electrocatalytic Properties

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

Zhu, Chengzhou; Shi, Qiurong; Fu, Shaofang

2018-04-04

Delicately engineering the well-defined noble metal aerogels with favorable structural and compositional features is of vital importance for wide applications. Here, we reported one-pot and facile method for synthesizing core-shell PdPb@Pd hydrogels/aerogels with multiply-twinned grains and ordered intermetallic phase using sodium hypophosphite as a multifunctional reducing agent. Due to the accelerated gelation kinetics induced by increased reaction temperature and specific function of sodium hypophosphite, the formation of hydrogels can be completed within 4 hrs, far faster than the previous reports. Owe to their unique porous structure and favorable geometric and electronic effects, the optimized PdPb@Pd aerogels exhibit enhanced electrochemical performancemore » towards ethylene glycol oxidation with a mass activity of 5.8 times higher than Pd black.« less

Carbon Microfibers with Hierarchical Porous Structure from Electrospun Fiber-Like Natural Biopolymer

NASA Astrophysics Data System (ADS)

Liang, Yeru; Wu, Dingcai; Fu, Ruowen

2013-01-01

Electrospinning offers a powerful route for building one-dimensional (1D) micro/nanostructures, but a common requirement for toxic or corrosive organic solvents during the preparation of precursor solution has limited their large scale synthesis and broad applications. Here we report a facile and low-cost way to prepare 1D porous carbon microfibers by using an electrospun fiber-like natural product, i.e., silk cocoon, as precursor. We surprisingly found that by utilizing a simple carbonization treatment, the cocoon microfiber can be directly transformed into 1D carbon microfiber of ca. 6 μm diameter with a unique three-dimensional porous network structure composed of interconnected carbon nanoparticles of 10~40 nm diameter. We further showed that the as-prepared carbon product presents superior electrochemical performance as binder-free electrodes of supercapacitors and good adsorption property toward organic vapor.

Rod-like hierarchical Sn/SnOx@C nanostructures with enhanced lithium storage properties

NASA Astrophysics Data System (ADS)

Yang, Juan; Chen, Sanmei; Tang, Jingjing; Tian, Hangyu; Bai, Tao; Zhou, Xiangyang

2018-03-01

Rod-like hierarchical Sn/SnOx@C nanostructures have been designed and synthesized via calcining resorcinol-formaldehyde (RF) resin coated Sn-based metal-organic frameworks. The rod-like hierarchical Sn/SnOx@C nanostructures are made of a great number of carbon-wrapped primary Sn/SnOx nanospheres of 100-200 nm in diameter. The as-prepared hierarchical Sn/SnOx@C nanocomposite manifests a high initial reversible capacity of 1177 mAh g-1 and remains 1001 mAh g-1 after 240 cycles at a current density of 200 mA g-1. It delivers outstanding high-rate performance with a reversible capacity of 823 mAh g-1 even at a high current density of 1000 mA g-1. The enhanced electrochemical performances of the Sn/SnOx@C electrode are mainly attributed to the synergistic effect of the unique hierarchical micro/nanostructures and the protective carbon layer.

Gold nanoparticles coated polystyrene/reduced graphite oxide microspheres with improved dispersibility and electrical conductivity for dopamine detection.

PubMed

Qian, Tao; Yu, Chenfei; Wu, Shishan; Shen, Jian

2013-12-01

Gold nanoparticles coated polystyrene/reduced graphite oxide (AuNPs@PS/RGO) microspheres have been successfully prepared via a facile process, and the decorative gold nanoparticles could prevent the aggregation of RGO by electrostatic repulsive interaction, and lead to high dispersibility of the composite. The prepared composite has a highly increased conductivity of 129Sm(-1) due to the unique electrical properties of citrate reduced gold nanoparticles. Being employed as an electrochemical sensor for detection of dopamine, the modified electrode exhibits remarkable sensitivity (3.44μA/μM) and lower detection limit (5nM), with linear response in a range of 0.05-20μM. Moreover, valid response to dopamine obtained in present work also indicates the prospective performances of AuNPs@PS/RGO microspheres to other biological molecules, such as nucleic acids, proteins and enzymes. Copyright © 2013 Elsevier B.V. All rights reserved.

[NiFe] hydrogenases: a common active site for hydrogen metabolism under diverse conditions.

PubMed

Shafaat, Hannah S; Rüdiger, Olaf; Ogata, Hideaki; Lubitz, Wolfgang

2013-01-01

Hydrogenase proteins catalyze the reversible conversion of molecular hydrogen to protons and electrons. The most abundant hydrogenases contain a [NiFe] active site; these proteins are generally biased towards hydrogen oxidation activity and are reversibly inhibited by oxygen. However, there are [NiFe] hydrogenase that exhibit unique properties, including aerobic hydrogen oxidation and preferential hydrogen production activity; these proteins are highly relevant in the context of biotechnological devices. This review describes four classes of these "nonstandard" [NiFe] hydrogenases and discusses the electrochemical, spectroscopic, and structural studies that have been used to understand the mechanisms behind this exceptional behavior. A revised classification protocol is suggested in the conclusions, particularly with respect to the term "oxygen-tolerance". This article is part of a special issue entitled: metals in bioenergetics and biomimetics systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Conducting Polymers in the Fields of Energy, Environmental Remediation, and Chemical-Chiral Sensors.

PubMed

Ibanez, Jorge G; Rincón, Marina E; Gutierrez-Granados, Silvia; Chahma, M'hamed; Jaramillo-Quintero, Oscar A; Frontana-Uribe, Bernardo A

2018-05-09

Conducting polymers (CPs), thanks to their unique properties, structures made on-demand, new composite mixtures, and possibility of deposit on a surface by chemical, physical, or electrochemical methodologies, have shown in the last years a renaissance and have been widely used in important fields of chemistry and materials science. Due to the extent of the literature on CPs, this review, after a concise introduction about the interrelationship between electrochemistry and conducting polymers, is focused exclusively on the following applications: energy (energy storage devices and solar cells), use in environmental remediation (anion and cation trapping, electrocatalytic reduction/oxidation of pollutants on CP based electrodes, and adsorption of pollutants) and finally electroanalysis as chemical sensors in solution, gas phase, and chiral molecules. This review is expected to be comprehensive, authoritative, and useful to the chemical community interested in CPs and their applications.

High rate capacitive performance of single-walled carbon nanotube aerogels

DOE PAGES

Van Aken, Katherine L.; Pérez, Carlos R.; Oh, Youngseok; ...

2015-05-30

Single-walled carbon nanotube (SWCNT) aerogels produced by critical-point-drying of wet-gel precursors exhibit unique properties, such as high surface-area-to-volume and strength-to-weight ratios. They are free-standing, are binder-free, and can be scaled to thicknesses of more than 1 mm. In this paper, we examine the electric double layer capacitive behavior of these materials using a common room temperature ionic liquid electrolyte, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI). Electrochemical performance is assessed through galvanostatic cycling, cyclic voltammetry and impedance spectroscopy. Results indicate stable capacitive performance over 10,000 cycles as well as an impressive performance at high charge and discharge rates, due to accessible pore networks andmore » enhanced electronic and ionic conductivities of SWCNT aerogels. Finally, these materials can find applications in mechanically compressible and flexible supercapacitor devices with high power requirements.« less

PdCuPt Nanocrystals With Multi-branches for Enzyme-free Glucose Detection

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

Fu, Shaofang; Zhu, Chengzhou; Song, Junhua

By carefully controlling the synthesis condition, branched PtCu bimetallic templates were synthesized in aqueous solution. After the galvanic replacement reaction between PtCu templates and the Pt precursors, PdCuPt trimetallic nanocrystals with branched structures were obtained. Owing to the open structure and the optimized composition, the electrochemical experimental results reveal that the PdCuPt trimetallic nanocrystals exhibit high electrocatalytic activity, selectivity and stability for the oxidation of glucose in alkaline solution. In details, a sensitivity of 378 μA/mM/cm2 and a detection limit of 1.29 μM can be achieved. The good electrocatalytic performance should be attributed to the unique branched nanostructure as wellmore » as the synergistic effect among metals. The superior catalytic properties suggest that these nanocrystals are promising for enzyme-free detection of glucose.« less

Polymer-Coated Graphene Aerogel Beads and Supercapacitor Application.

PubMed

Ouyang, An; Cao, Anyuan; Hu, Song; Li, Yanhui; Xu, Ruiqiao; Wei, Jinquan; Zhu, Hongwei; Wu, Dehai

2016-05-04

Graphene aerogels are highly porous materials with many energy and environmental applications; tailoring the structure and composition of pore walls within the aerogel is the key to those applications. Here, by freeze casting the graphene oxide sheets, we directly fabricated freestanding porous graphene beads containing radially oriented through channels from the sphere center to its surface. Furthermore, we introduced pseudopolymer to make reinforced, functional composite beads with a unique pore morphology. We showed that polymer layers can be coated smoothly on both sides of the pore walls, as well as on the junctions between adjacent pores, resulting in uniform polymer-graphene-polymer sandwiched structures (skeletons) throughout the bead. These composite beads significantly improved the electrochemical properties, with specific capacitances up to 669 F/g and good cyclic stability. Our results indicate that controlled fabrication of homogeneous hierarchical structures is a potential route toward high performance composite electrodes for various energy applications.

Synthesis of V2O5 microspheres by spray pyrolysis as cathode material for supercapacitors

NASA Astrophysics Data System (ADS)

Yin, Zhendong; Xu, Jie; Ge, Yali; Jiang, Qiaoya; Zhang, Yaling; Yang, Yawei; Sun, Yuping; Hou, Siyu; Shang, Yuanyuan; Zhang, Yingjiu

2018-03-01

Vanadium oxide (V2O5) microspheres have attracted considerable attention in the energy field due to their unique properties such as high stability and electrochemical activity. Here, massive V2O5 microspheres with smooth surface, hollow cavity and uniform particle sizes (0.4–1.5 μm), were synthesized by a facile spray pyrolysis process. Post-treatment at predefined temperatures effectively turned the microsphere shell into stacked nanorods with widths of 100 nm and lengths of 500 nm when processed at 500 °C for 3 h under nitrogen atmosphere, with enhanced crystallinity. When applied as cathode materials for supercapacitors, the post-treated V2O5 microspheres at 500 °C exhibited improved specific capacitance and longer discharge time. This is an effective method to manufacture massive V2O5 microspheres with tailored structure and potential applications in high-performance energy storage materials.

Synthesis of a New Family of Hexakisferrocenyl Hexagons and Their Electrochemical Behavior

PubMed Central

Ghosh, Koushik; Zhao, Yue; Yang, Hai-Bo; Northrop, Brian H.

2009-01-01

The design and synthesis of two new hexakisferrocenyl hexagons has been achieved via coordination-driven self-assembly wherein the size and relative distribution of six ferrocene moieties has been precisely controlled. Insight into the structure and electronic properties of these supramolecules was obtained through electrochemical studies. PMID:18841907

Physical Properties of Pyridinium Fluorohydrogenate, [pyridine · H+][H2F3]-

NASA Astrophysics Data System (ADS)

Hulse, Ryan; Singh, Rajiv

2008-12-01

Ionic liquids (ILs), also referred to as molten salts, have found application as electrolytes for batteries and super-capacitors, in electroplating baths, as designer solvents, and as reaction media. A few of the desired properties of a super-capacitor electrolyte are nonflammability, thermal stability, and electrochemical stability. ILs containing aromatic cations have been shown to have low viscosity which results in a high electrochemical conductivity. There is a delicate balance between increasing the thermal stability, or decreasing the melting point, and increasing the electrochemical conductivity of the IL. This study focuses on pyridinium fluorohydrogenate, [pyridine · H+][H2F3]-. Pyridinium fluorohydrogenate has been synthesized by the reaction of pyridine and anhydrous hydrofluoric acid. This IL has a relatively high electrical conductivity (~98 mS · cm-1 at 23 °C), a wide electrochemical window, and a boiling point of 186 °C. A stable gel can also be formed by combining [pyridine · H+][H2F3]- and a super absorbent polymer such as polyacrylic acid. The gel adds mechanical stability to the matrix while not greatly affecting the conductivity of the IL.

Effects of Electrodeposition Mode and Deposition Cycle on the Electrochemical Performance of MnO2-NiO Composite Electrodes for High-Energy-Density Supercapacitors.

PubMed

Rusi; Majid, S R

2016-01-01

Nanostructured network-like MnO2-NiO composite electrodes were electrodeposited onto stainless steel substrates via different electrodeposition modes, such as chronopotentiometry, chronoamperometry, and cyclic voltammetry, and then subjected to heat treatment at 300°C for metal oxide conversion. X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to study the crystalline natures and morphologies of the deposited films. The electrochemical properties were investigated using cyclic voltammetry and charge/discharge tests. The results revealed that the electrochemical performance of the as-obtained composite electrodes depended on the electrodeposition mode. The electrochemical properties of MnO2-NiO composite electrodes prepared using cyclic voltammetry exhibited the highest capacitance values and were most influenced by the deposition cycle number. The optimum specific capacitance was 3509 Fg-1 with energy and power densities of 1322 Wh kg-1 and 110.5 kW kg-1, respectively, at a current density of 20 Ag-1 in a mixed KOH/K3Fe(CN)6 electrolyte.

PdCo alloy nanoparticle-embedded carbon nanofiber for ultrasensitive nonenzymatic detection of hydrogen peroxide and nitrite.

PubMed

Liu, Dong; Guo, Qiaohui; Zhang, Xueping; Hou, Haoqing; You, Tianyan

2015-07-15

PdCo alloy nanoparticle-embedded carbon nanofiber (PdCo/CNF) prepared by electrospinning and thermal treatment was employed as a high-performance platform for the determination of hydrogen peroxide and nitrite. The as-obtained PdCo/CNF were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were employed to investigate the electrochemical behaviors of the resultant biosensor. The proposed PdCo/CNF-based biosensor showed excellent analytical performances toward hydrogen peroxide (detection limit: 0.1 μM; linear range: 0.2 μM-23.5 mM) and nitrite (detection limit: 0.2 μM; linear range: 0.4-30 μM and 30-400 μM). The superior analytical properties could be attributed to the synergic effect and firmly embedment of well-dispersed PdCo alloy nanoparticles. These attractive electrochemical properties make this robust electrode material promising for the development of effective electrochemical sensors. Copyright © 2015 Elsevier Inc. All rights reserved.

Facile synthesis of Co(OH)2/Al(OH)3 nanosheets with improved electrochemical properties for asymmetric supercapacitor

NASA Astrophysics Data System (ADS)

Zhao, Cuimei; Ren, Fang; Cao, Yang; Xue, Xiangxin; Duan, Xiaoyue; Wang, Hairui; Chang, Limin

2018-01-01

Sheet-like Co(OH)2/Al(OH)3 or Co(OH)2 nanomaterial has been synthesized on conducting carbon fiber paper (CFP) by a facile one-step electrochemical deposition. The binder-free Co(OH)2/Al(OH)3/CFP displays an improved electrical conductivity, electrochemical activity and material utilization than solitary Co(OH)2, therefore Co(OH)2/Al(OH)3 nanomaterial exhibits improved electrochemical properties (a maximum capacitance of 1006 Fg-1 at 2 Ag-1, with 77% retention even at a high current density of 32 Ag-1, and more than 87% of the capacitance retention after 10000 cycles at 32 Ag-1) in comparison to that of the Co(OH)2/CFP (709 Fg-1, 65%, 79%). In addition, an asymmetric supercapacitor (ASC) fabricated with Co(OH)2/Al(OH)3/CFP positive electrode and AC/CFP negative electrode demonstrates ultrahigh specific capacitance (75.8 Fg-1) and potential window (1.7 V). These encouraging results make these low-cost and eco-friendly materials promising for high-performance energy storage application.

Synthesis and electrochemical properties of layered structure Li[Ni{sub 0.5}Co{sub 0.25}Mn{sub 0.25}]O{sub 2} cathode material

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

Prathibha, G.; Rosaiah, P.; Reddy, B. Purusottam

Lithium ion (Li-ion) batteries are currently the energy source of choice for cell phones, laptops, and other mobile electronic devices due to their balance of high energy density with high power density compared to other electrochemical energy carriers. In the present study, mixed hydroxide method is used to prepare Li[Ni{sub 0.5}Co{sub 0.25}Mn{sub 0.25}]O{sub 2} from the precursors and analyze qualitatively and studied the electrochemical properties. The XRD spectrum exhibited predominant (003) orientation at 2θ =18.39{sup o} corresponding to hexagonal layered structure of R3m symmetry with evaluated lattice parameters are a= 2.84 Å, c= 14.43 Å. Raman measurements were performed tomore » understand the microstructure and vibrational modes of the prepared sample. From the electrochemical (EC) studies an initial discharge capacity of about 140 mAhg{sup −1} with good cyclic stability was observed for the prepared sample in the potential range 0.0 −1.0V in aqueous medium.« less

Effects of Electrodeposition Mode and Deposition Cycle on the Electrochemical Performance of MnO2-NiO Composite Electrodes for High-Energy-Density Supercapacitors

PubMed Central

Rusi; Majid, S. R.

2016-01-01

Nanostructured network-like MnO2-NiO composite electrodes were electrodeposited onto stainless steel substrates via different electrodeposition modes, such as chronopotentiometry, chronoamperometry, and cyclic voltammetry, and then subjected to heat treatment at 300°C for metal oxide conversion. X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to study the crystalline natures and morphologies of the deposited films. The electrochemical properties were investigated using cyclic voltammetry and charge/discharge tests. The results revealed that the electrochemical performance of the as-obtained composite electrodes depended on the electrodeposition mode. The electrochemical properties of MnO2-NiO composite electrodes prepared using cyclic voltammetry exhibited the highest capacitance values and were most influenced by the deposition cycle number. The optimum specific capacitance was 3509 Fg−1 with energy and power densities of 1322 Wh kg−1 and 110.5 kW kg−1, respectively, at a current density of 20 Ag−1 in a mixed KOH/K3Fe(CN)6 electrolyte. PMID:27182595

Synthesis and property of spinel porous ZnMn2O4 microspheres

NASA Astrophysics Data System (ADS)

Guo, N.; Wei, X. Q.; Deng, X. L.; Xu, X. J.

2015-11-01

Mesoporous ternary zinc manganese oxides on the Ti sheet substrate are prepared by easy and fast hydrothermal method for the first time. The obtained ZnMn2O4 materials with homogenously distributed pores have been characterized by XRD, SEM and Raman spectra, which show the good crystal phase and particles for improving supercapacitive performance. XRD and SEM images show that the as-prepared samples have good crystallinity, and ZnMn2O4 microsphere has an average diameter of 10 μm. In addition, ZnMn2O4 are also characterized in 2 M KOH solution using three-electrode system. In the work, we study that different substrates (Ti, carbon and nickel foam) have an important effect on the electrochemical performance of the samples. The research of cyclic voltammogram (CV) indicates that the obtained specific capacitance (155 F g-1) values on nickel foam substrate for the ZnMn2O4 microspheres are higher than the values reported for some inexpensive oxides. However, the specific capacitance of all ZnMn2O4 samples has almost no change at two different scan rates which shows good long-term cycling stability. The electrochemical impedance spectroscopy with a small resistance reveals that the as-synthesized samples have good frequency response characteristics. These results indicate that the unique ZnMn2O4 electrode would be a promising electrode for high-performance supercapacitor applications.

Towards Next Generation Lithium-Sulfur Batteries: Non-Conventional Carbon Compartments/Sulfur Electrodes and Multi-Scale Analysis

DOE PAGES

Dysart, Arthur D.; Burgos, Juan C.; Mistry, Aashutosh; ...

2016-02-09

In this work, a novel heterofunctional, bimodal-porous carbon morphology, termed the carbon compartment (CC), is utilized as a sulfur host as a lithium-sulfur battery cathode. A multi-scale model explores the physics and chemistry of the lithium-sulfur battery cathode. The CCs are synthesized by a rapid, low cost process to improve electrode-electrolyte interfacial contact and accommodate volumetric expansion associated with sulfide formation. The CCs demonstrate high sulfur loading (47 %-wt. S) and ca. 700 mAh g -1 reversible capacity with high coulombic efficiency due to their unique structures. Density functional theory and ab initio Molecular Dynamics characterize the interface between themore » C/S composite and electrolyte during the sulfur reduction mechanism. Stochastic realizations of 3D electrode microstructures are reconstructed based on representative SEM images to study the influence of solid sulfur loading and lithium sulfide precipitation on microstructural and electrochemical properties. A macroscale electrochemical performance model is developed to analyze the performance of lithium-sulfur batteries. The combined multi-scale simulation studies explain key fundamentals of sulfur reduction and its relation to the polysulfide shuttle mechanism: how the process is affected due to the presence of carbon substrate, thermodynamics of lithium sulfide formation and deposition on carbon, and microstructural effects on the overall cell performance.« less

Determination of kojic acid based on the interface enhancement effects of carbon nanotube/alizarin red S modified electrode.

PubMed

Liu, Jieshu; Zhou, Dazhai; Liu, Xiaopeng; Wu, Kangbing; Wan, Chidan

2009-04-01

Based on non-covalent interactions such as pi-pi stacking, van der Waals interactions and strong adsorption, alizarin red S (ARS) interacts with multi-walled carbon nanotubes (MWNT), improving the solubility of MWNT in water and resulting in a stable MWNT/ARS solution. By successive cyclic sweeps between 0.0 and 2.2V in the MWNT/ARS solution, a MWNT/ARS composite film was fabricated on an electrode surface. The electrochemical behaviors of kojic acid at the bare electrode, the ARS film-modified electrode and the MWNT/ARS film-modified electrode were investigated. It was found that the oxidation signal of kojic acid significantly increased at the MWNT/ARS film-modified electrode, which was attributed to the unique properties of MWNT such as large surface area, strong adsorptive ability and subtle electronic character. The effects of pH and cyclic number of electropolymerization were examined. A rapid, sensitive and simple electrochemical method was then developed for the determination of kojic acid. This method exhibits good linearity over the range from 4.0 x 10(-7) to 6.0 x 10(-5)mol L(-1), and the limit of detection is as low as 1.0 x 10(-7)mol L(-1). In order to validate feasibility, the MWNT/ARS film-modified electrode was used for quantitative analysis of kojic acid in food samples.

Covalently functionalized single-walled carbon nanotubes and graphene composite electrodes for pseudocapacitor application

NASA Astrophysics Data System (ADS)

Le Barny, Pierre; Servet, Bernard; Campidelli, Stéphane; Bondavalli, Paolo; Galindo, Christophe

2013-09-01

The use of carbon-based materials in electrochemical double-layer supercapacitors (EDLC) is currently being the focus of much research. Even though activated carbon (AC) is the state of the art electrode material, AC suffers from some drawbacks including its limited electrical conductivity, the need for a binder to ensure the expected electrode cohesion and its limited accessibility of its pores to solvated ions of the electrolyte. Owing to their unique physical properties, carbon nanotubes (CNTs) or graphene could overcome these drawbacks. It has been demonstrated that high specific capacitance could be obtained when the carbon accessible surface area of the electrode was finely tailored by using graphene combined with other carbonaceous nanoparticles such as CNTs12.In this work, to further increase the specific capacitance of the electrode, we have covalently grafted onto the surface of single-walled carbon nanotubes (SWCNTs), exfoliated graphite or graphene oxide (GO), anthraquinone (AQ) derivatives which are electrochemically active materials. The modified SWCNTs and graphene-like materials have been characterized by Raman spectroscopy, X-ray photoemission and cyclic voltammetry . Then suspensions based on mixtures of modified SWCNTs and modified graphene-like materials have been prepared and transformed into electrodes either by spray coating or by filtration. These electrodes have been characterized by SEM and by cyclic voltammetry in 0.1M H2S04 electrolyte.

Yolk-Shelled C@Fe3 O4 Nanoboxes as Efficient Sulfur Hosts for High-Performance Lithium-Sulfur Batteries.

PubMed

He, Jiarui; Luo, Liu; Chen, Yuanfu; Manthiram, Arumugam

2017-09-01

Owing to the high theoretical specific capacity (1675 mA h g -1 ) and low cost, lithium-sulfur (Li-S) batteries offer advantages for next-generation energy storage. However, the polysulfide dissolution and low electronic conductivity of sulfur cathodes limit the practical application of Li-S batteries. To address such issues, well-designed yolk-shelled carbon@Fe 3 O 4 (YSC@Fe 3 O 4 ) nanoboxes as highly efficient sulfur hosts for Li-S batteries are reported here. With both physical entrapment by carbon shells and strong chemical interaction with Fe 3 O 4 cores, this unique architecture immobilizes the active material and inhibits diffusion of the polysulfide intermediates. Moreover, due to their high conductivity, the carbon shells and the polar Fe 3 O 4 cores facilitate fast electron/ion transport and promote continuous reactivation of the active material during the charge/discharge process, resulting in improved electrochemical utilization and reversibility. With these merits, the S/YSC@Fe 3 O 4 cathodes support high sulfur content (80 wt%) and loading (5.5 mg cm -2 ) and deliver high specific capacity, excellent rate capacity, and long cycling stability. This work provides a new perspective to design a carbon/metal-oxide-based yolk-shelled framework as a high sulfur-loading host for advanced Li-S batteries with superior electrochemical properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchically porous carbon nanosheets derived from Moringa oleifera stems as electrode material for high-performance electric double-layer capacitors

NASA Astrophysics Data System (ADS)

Cai, Yijin; Luo, Ying; Dong, Hanwu; Zhao, Xiao; Xiao, Yong; Liang, Yeru; Hu, Hang; Liu, Yingliang; Zheng, Mingtao

2017-06-01

A facile one-step pyrolysis route for the synthesis of hierarchically porous carbon nanosheets (PCNSs) derived from Moringa oleifera stems (MOSs) is reported, in which no post-activation-process in needed. The as-prepared PCNSs possesses unique porous nanosheet morphology with high specific surface area of ca. 2250 m2 g-1, large pore volume of ca. 2.3 cm3 g-1, appropriate porosity as well as heteroatom doping (N and O), endowing outstanding electrochemical properties as electrode material for high-performance supercapacitors. The PCNS-based electrodes are investigated in various aqueous electrolytes including 1.0 M Na2SO4, 1.0 M H2SO4, and 6.0 M KOH. The PCNSs exhibit a maximum specific capacitance of ca. 283 F g-1 (0.5 A g-1), excellent rate capability (ca. 72% of capacitance retention even at an ultrahigh current density of 50 A g-1), and a tremendous long-term cycling stability in the three-electrode system. Moreover, the as-assembled PCNS-based symmetric supercapacitor shows a high energy density of ca. 25.8 Wh kg-1 (in 1.0 M Na2SO4 electrolyte) and remarkable long-term cycling stability (almost no capacitance fade in aqueous electrolytes), indicating the promising of the as-prepared PCNSs for electrochemical energy storage and conversion.

Enzyme-modified nanoporous gold-based electrochemical biosensors.

PubMed

Qiu, Huajun; Xue, Luyan; Ji, Guanglei; Zhou, Guiping; Huang, Xirong; Qu, Yinbo; Gao, Peiji

2009-06-15

On the basis of the unique physical and chemical properties of nanoporous gold (NPG), which was obtained simply by dealloying Ag from Au/Ag alloy, an attempt was made in the present study to develop NPG-based electrochemical biosensors. The NPG-modified glassy carbon electrode (NPG/GCE) exhibited high-electrocatalytic activity toward the oxidation of nicotinamide adenine dinucleotide (NADH) and hydrogen peroxide (H(2)O(2)), which resulted in a remarkable decrease in the overpotential of NADH and H(2)O(2) electro-oxidation when compared with the gold sheet electrode. The high density of edge-plane-like defective sites and large specific surface area of NPG should be responsible for the electrocatalytic behavior. Such electrocatalytic behavior of the NPG/GCE permitted effective low-potential amperometric biosensing of ethanol or glucose via the incorporation of alcohol dehydrogenase (ADH) or glucose oxidase (GOD) within the three-dimensional matrix of NPG. The ADH- and GOD-modified NPG-based biosensors showed good analytical performance for biosensing ethanol and glucose due to the clean, reproducible and uniformly distributed microstructure of NPG. The stabilization effect of NPG on the incorporated enzymes also made the constructed biosensors very stable. After 1 month storage at 4 degrees C, the ADH- and GOD-based biosensors lost only 5.0% and 4.2% of the original current response. All these indicated that NPG was a promising electrode material for biosensors construction.

The electrochemical exploration of double carbon-wrapped Na3V2(PO4)3: Towards long-time cycling and superior rate sodium-ion battery cathode

NASA Astrophysics Data System (ADS)

Li, Sijie; Ge, Peng; Zhang, Chenyang; Sun, Wei; Hou, Hongshuai; Ji, Xiaobo

2017-10-01

Na3V2(PO4)3 (NVP) is a very promising cathode material in sodium ion battery for rapidly emerging large-scale energy storage with its classical 3D NASCION structure. However, the cycling life and rate performances are restricted its low electronic conductivity. To overcome these, the double carbon-wrapped Na3V2(PO4)3 composite is firstly designed through rheological phase approach, delivering enhanced electrochemical properties. The unique double carbon layers are composed of uniform amorphous carbons as protecting framework for stabilizing the structure, as well as the graphitized carbon sheets playing the role of conductive network for better electronic conductivity. This double carbon-wrapped Na3V2(PO4)3 composite exhibits a high reversible capacity of 99.8 mAh g-1 over 500 cycles at 1 C (110 mA g-1), yielding the coulombic efficiency of ∼99.8%. Meanwhile, it displays an initial capacity of 73 mAh g-1 at 100 C and remains 55 mAh g-1 at an ultra-rate of 200 C. Even after cycling at 200 C over 12 000 cycles, the Na+-storage capacity of 40 mAh g-1 with a retention of 72.7% is still obtained, highlighting its excellent long cycling life and remarkable rate performances.

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

Brodsky, Casey N.; Hadt, Ryan G.; Hayes, Dugan

The Co 4O 4 cubane is a representative structural model of oxidic cobalt oxygen evolving catalysts (Co-OECs). The Co-OECs are active when residing at two oxidation levels above an all Co(III) resting state. This doubly oxidized Co(IV) 2 state may be captured in a Co(III) 2(IV) 2 cubane. We demonstrate that the Co(III) 2(IV) 2 cubane may be electrochemically generated and the electronic properties of this unique high-valent state may be probed by in situ spectroscopy. Intervalence charge transfer (IVCT) bands in the near-IR are observed for the Co(III) 2(IV) 2 cubane, and spectroscopic analysis together with electrochemical kinetics measurementsmore » reveal a larger reorganization energy and a smaller electron transfer rate constant for the doubly versus singly oxidized cubane. Spectroelectrochemical X-ray absorption data further reveal systematic spectral changes with successive oxidations from the cubane resting state. Electronic structure calculations correlated to experimental data suggest that this state is best represented as a localized, antiferromagnetically coupled Co(IV) 2 dimer. The exchange coupling in the cofacial Co(IV) 2 site allows for parallels to be drawn between the electronic structure of the Co 4O 4 cubane model system and the high valent active site of the Co-OEC, with specific emphasis on the manifestation of a doubly oxidized Co(IV) 2 center on O–O bond formation.« less

Microwave-assisted synthesis and electrochemical evaluation of VO 2 (B) nanostructures

DOE PAGES

Ashton, Thomas E.; Borras, David Hevia; Iadecola, Antonella; ...

2015-12-01

Understanding how intercalation materials change during electrochemical operation is paramount to optimising their behaviour and function and in situ characterisation methods allow us to observe these changes without sample destruction. Here, we first report the improved intercalation properties of bronze phase vanadium dioxide VO2 (B) prepared by a microwave assisted route which exhibits a larger electrochemical capacity (232 mAh g -1) compared to VO 2 (B) prepared by a solvothermal route (197 mAh g -1). These electrochemical differences have also been followed using in situ X-ray absorption spectroscopy allowing us to follow oxidation state changes as they occur during batterymore » operation.« less

Exploring electrolyte preference of vanadium nitride supercapacitor electrodes

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

Wang, Bo; Chen, Zhaohui; Lu, Gang

Highlights: • Hierarchical VN nanostructures were prepared on graphite foam. • Electrolyte preference of VN supercapacitor electrodes was explored. • VN showed better capacitive property in organic and alkaline electrolytes than LiCl. - Abstract: Vanadium nitride hierarchical nanostructures were prepared through an ammonia annealing procedure utilizing vanadium pentoxide nanostructures grown on graphite foam. The electrochemical properties of hierarchical vanadium nitride was tested in aqueous and organic electrolytes. As a result, the vanadium nitride showed better capacitive energy storage property in organic and alkaline electrolytes. This work provides insight into the charge storage process of vanadium nitride and our findings canmore » shed light on other transition metal nitride-based electrochemical energy storage systems.« less

Diagnostics Strategies with Electrochemical Affinity Biosensors Using Carbon Nanomaterials as Electrode Modifiers

PubMed Central

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

2016-01-01

Early diagnosis is often the key to successful patient treatment and survival. The identification of various disease signaling biomarkers which reliably reflect normal and disease states in humans in biological fluids explain the burgeoning research field in developing new methodologies able to determine the target biomarkers in complex biological samples with the required sensitivity and selectivity and in a simple and rapid way. The unique advantages offered by electrochemical sensors together with the availability of high affinity and specific bioreceptors and their great capabilities in terms of sensitivity and stability imparted by nanostructuring the electrode surface with different carbon nanomaterials have led to the development of new electrochemical biosensing strategies that have flourished as interesting alternatives to conventional methodologies for clinical diagnostics. This paper briefly reviews the advantages of using carbon nanostructures and their hybrid nanocomposites as electrode modifiers to construct efficient electrochemical sensing platforms for diagnosis. The review provides an updated overview of some selected examples involving attractive amplification and biosensing approaches which have been applied to the determination of relevant genetic and protein diagnostics biomarkers. PMID:28035946

Pitting corrosion as a mixed system: coupled deterministic-probabilistic simulation of pit growth

NASA Astrophysics Data System (ADS)

Ibrahim, Israr B. M.; Fonna, S.; Pidaparti, R.

2018-05-01

Stochastic behavior of pitting corrosion poses a unique challenge in its computational analysis. However, it also stems from electrochemical activity causing general corrosion. In this paper, a framework for corrosion pit growth simulation based on the coupling of the Cellular Automaton (CA) and Boundary Element Methods (BEM) is presented. The framework assumes that pitting corrosion is controlled by electrochemical activity inside the pit cavity. The BEM provides the prediction of electrochemical activity given the geometrical data and polarization curves, while the CA is used to simulate the evolution of pit shapes based on electrochemical activity provided by BEM. To demonstrate the methodology, a sample case of local corrosion cells formed in pitting corrosion with varied dimensions and polarization functions is considered. Results show certain shapes tend to grow in certain types of environments. Some pit shapes appear to pose a higher risk by being potentially significant stress raisers or potentially increasing the rate of corrosion under the surface. Furthermore, these pits are comparable to commonly observed pit shapes in general corrosion environments.

Comparative studies of structural, thermal, optical, and electrochemical properties of azines with different end groups with their azomethine analogues toward application in (opto)electronics.

PubMed

Sek, Danuta; Siwy, Mariola; Bijak, Katarzyna; Grucela-Zajac, Marzena; Malecki, Grzegorz; Smolarek, Karolina; Bujak, Lukasz; Mackowski, Sebastian; Schab-Balcerzak, Ewa

2013-10-10

Two series of azines and their azomethine analogues were prepared via condensation reaction of benzaldehyde, 2-hydroxybenzaldehyde, 4-pyridinecarboxaldehyde, 2-thiophenecarboxaldehyde, and 4-(diphenylamino)benzaldehyde with hydrazine monohydrate and 1,4-phenylenediamine, respectively. The structures of given compounds were characterized by FTIR, (1)H NMR, and (13)C NMR spectroscopy as well as elemental analysis. Optical, electrochemical, and thermal properties of all compounds were investigated by means of differential scanning calorimetry (DSC), UV-vis spectroscopy, stationary and time-resolved photoluminescence spectroscopy, and cycling voltammetry (CV). Additionally, the electronic properties, that is, orbital energies and resulting energy gap were calculated theoretically by density functional theory (DFT). Influence of chemical structure of the compounds on their properties was analyzed.

Electrochemical insertion of magnesium ions into V2O5 from aprotic electrolytes with varied water content.

PubMed

Yu, Long; Zhang, Xiaogang

2004-10-01

The electrochemical performance of V2O5 has been studied in propylene carbonate (PC)-containing magnesium perchlorate [Mg(ClO4)2] electrolytes in view of their application as positive electrode in the rechargeable magnesium batteries. V2O5 exhibited good properties in hosting magnesium ions and its electrochemical performance depended on the amount of H2O in the electrolytes. The highest first discharge specific capacities of V2O5 electrode was up to 158.6 mAh/g in 1 mol dm(-3) Mg(ClO4)2 + 1.79 mol dm(-3) H2O/PC electrolytes. Electrochemical impedance spectroscopy (EIS) and charging-discharging tests showed that a reasonable amount of H2O in the electrolyte solution facilitated the electrochemical performance of V2O5 electrodes.

Effect of the Cerium Oxide (CeO2) on the Structural and Electrochemical Properties of the LaNi5Ce Metal Hydride Anode

NASA Astrophysics Data System (ADS)

Utami Hapsari, Ade; Zulfia, Anne; Raharjo, Jarot; Agustanhakri

2017-07-01

One of negative electrode, AB5-type alloy electrodes, have been extensively studied and applied in rechargeable Ni-MH batteries due to their excellent electrochemical characteristics. Some researchers have found that addition of rare earth oxides (La, Ce, Pr, Er, Tm, Yb) to AB5-type alloy (MH) electrode improves battery performance significantly. Cerium Oxide (CeO2) is a light rare earth oxide is widely obtained from the processing of tailings in mining activities. During this time, there is still little data for research applications of cerium oxide for electrode materials. In this paper, the effects of adding CeO2 on the performance metal hydride electrode were investigated. In order to study the effects of CeO2 on the performance of anode material, 1%, 2%, and 3% of weight ratio CeO2 was mixed to LaNi5 as an negative electrode. The powder mixtures were mechanically milled at a speed of rpm 240 for 2 hours using ball mill. The powder mixtures were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Electrochemical characteristics were measured using electrochemical impedance spectroscopy (EIS). The powder mixing showed the presence of Ce atom substitution into LaNi5 structures that affect the electrochemical properties of the material. The addition of cerium oxide at LaNi5 increase of the value of impedance. However, the addition of the value of impedance at 1% CeO2 is not significant when compared with the addition of 2% and 3% CeO2 that actually make the electrochemical properties of LaNi5 worst. Although the addition of 1% CeO2 also slightly increases the impedance value of LaNi5, but the addition of 1% CeO2 showed increase the corrosion resistance than without the addition of CeO2 and the addition of 2% and 3% CeO2.

Ultrathin Mesoporous RuCo2 O4 Nanoflakes: An Advanced Electrode for High-Performance Asymmetric Supercapacitors.

PubMed

Dubal, Deepak P; Chodankar, Nilesh R; Holze, Rudolf; Kim, Do-Heyoung; Gomez-Romero, Pedro

2017-04-22

A new ruthenium cobalt oxide (RuCo 2 O 4 ) with a unique marigold-like nanostructure and excellent performance as an advanced electrode material has been successfully prepared by a simple electrodeposition (potentiodynamic mode) method. The RuCo 2 O 4 marigolds consist of numerous clusters of ultrathin mesoporous nanoflakes, leaving a large interspace between them to provide numerous electrochemically active sites. Strikingly, this unique marigold-like nanostructure provided excellent electrochemical performance in terms of high energy-storage capacitance (1469 F g -1 at 6 A g -1 ) with excellent rate proficiency and long-lasting operating cycling stability (ca. 91.3 % capacitance retention after 3000 cycles), confirming that the mesoporous nanoflakes participate in the ultrafast electrochemical reactions. Furthermore, an asymmetric supercapacitor was assembled using RuCo 2 O 4 (positive electrode) and activated carbon (negative electrode) with aqueous KOH electrolyte. The asymmetric design allowed an upgraded potential range of 1.4 V, which further provided a good energy density of 32.6 Wh kg -1 (1.1 mWh cm -3 ). More importantly, the cell delivered an energy density of 12.4 Wh kg -1 even at a maximum power density of 3.2 kW kg -1 , which is noticeably superior to carbon-based symmetric systems. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Atomic scale deposition of Pt around Au nanoparticles to achieve much enhanced electrocatalysis of Pt

DOE PAGES

Xi, Zheng; Lv, Haifeng; Erdosy, Daniel P.; ...

2017-05-07

Here, we report an electrochemical method to deposit atomic scale Pt on a 5 nm Au nanoparticle (NP) surface in N 2-saturated 0.5 M H 2SO 4. Furthermore, Pt is provided by the Pt wire counter electrode via one-step Pt wire oxidation, dissolution, and deposition realized by controlled electrochemical scanning. Scanning from 0.6–1.0 V (vs. RHE) for 10 000 cycles gives Au 98.2Pt 1.8, which serves as an excellent catalyst for the formic acid oxidation reaction, showing 41 times higher specific activity (20.19 mA cm -2) and 25 times higher mass activity (10.80 A mg Pt -1) with much bettermore » CO-tolerance and stability than commercial Pt. This work demonstrates a unique strategy to minimize the use of Pt as a catalyst for electrochemical reactions.« less

Spine-like Nanostructured Carbon Interconnected by Graphene for High-performance Supercapacitors

NASA Astrophysics Data System (ADS)

Park, Sang-Hoon; Yoon, Seung-Beom; Kim, Hyun-Kyung; Han, Joong Tark; Park, Hae-Woong; Han, Joah; Yun, Seok-Min; Jeong, Han Gi; Roh, Kwang Chul; Kim, Kwang-Bum

2014-08-01

Recent studies on supercapacitors have focused on the development of hierarchical nanostructured carbons by combining two-dimensional graphene and other conductive sp2 carbons, which differ in dimensionality, to improve their electrochemical performance. Herein, we report a strategy for synthesizing a hierarchical graphene-based carbon material, which we shall refer to as spine-like nanostructured carbon, from a one-dimensional graphitic carbon nanofiber by controlling the local graphene/graphitic structure via an expanding process and a co-solvent exfoliation method. Spine-like nanostructured carbon has a unique hierarchical structure of partially exfoliated graphitic blocks interconnected by thin graphene sheets in the same manner as in the case of ligaments. Owing to the exposed graphene layers and interconnected sp2 carbon structure, this hierarchical nanostructured carbon possesses a large, electrochemically accessible surface area with high electrical conductivity and exhibits high electrochemical performance.

Spine-like nanostructured carbon interconnected by graphene for high-performance supercapacitors.

PubMed

Park, Sang-Hoon; Yoon, Seung-Beom; Kim, Hyun-Kyung; Han, Joong Tark; Park, Hae-Woong; Han, Joah; Yun, Seok-Min; Jeong, Han Gi; Roh, Kwang Chul; Kim, Kwang-Bum

2014-08-19

Recent studies on supercapacitors have focused on the development of hierarchical nanostructured carbons by combining two-dimensional graphene and other conductive sp(2) carbons, which differ in dimensionality, to improve their electrochemical performance. Herein, we report a strategy for synthesizing a hierarchical graphene-based carbon material, which we shall refer to as spine-like nanostructured carbon, from a one-dimensional graphitic carbon nanofiber by controlling the local graphene/graphitic structure via an expanding process and a co-solvent exfoliation method. Spine-like nanostructured carbon has a unique hierarchical structure of partially exfoliated graphitic blocks interconnected by thin graphene sheets in the same manner as in the case of ligaments. Owing to the exposed graphene layers and interconnected sp(2) carbon structure, this hierarchical nanostructured carbon possesses a large, electrochemically accessible surface area with high electrical conductivity and exhibits high electrochemical performance.

Spine-like Nanostructured Carbon Interconnected by Graphene for High-performance Supercapacitors

PubMed Central

Park, Sang-Hoon; Yoon, Seung-Beom; Kim, Hyun-Kyung; Han, Joong Tark; Park, Hae-Woong; Han, Joah; Yun, Seok-Min; Jeong, Han Gi; Roh, Kwang Chul; Kim, Kwang-Bum

2014-01-01

Recent studies on supercapacitors have focused on the development of hierarchical nanostructured carbons by combining two-dimensional graphene and other conductive sp2 carbons, which differ in dimensionality, to improve their electrochemical performance. Herein, we report a strategy for synthesizing a hierarchical graphene-based carbon material, which we shall refer to as spine-like nanostructured carbon, from a one-dimensional graphitic carbon nanofiber by controlling the local graphene/graphitic structure via an expanding process and a co-solvent exfoliation method. Spine-like nanostructured carbon has a unique hierarchical structure of partially exfoliated graphitic blocks interconnected by thin graphene sheets in the same manner as in the case of ligaments. Owing to the exposed graphene layers and interconnected sp2 carbon structure, this hierarchical nanostructured carbon possesses a large, electrochemically accessible surface area with high electrical conductivity and exhibits high electrochemical performance. PMID:25134517

An Overview on Recent Progress in Electrochemical Biosensors for Antimicrobial Drug Residues in Animal-Derived Food

PubMed Central

Majdinasab, Marjan; Yaqub, Mustansara; Rahim, Abdur; Catanante, Gaelle; Hayat, Akhtar; Marty, Jean Louis

2017-01-01

Anti-microbial drugs are widely employed for the treatment and cure of diseases in animals, promotion of animal growth, and feed efficiency. However, the scientific literature has indicated the possible presence of antimicrobial drug residues in animal-derived food, making it one of the key public concerns for food safety. Therefore, it is highly desirable to design fast and accurate methodologies to monitor antimicrobial drug residues in animal-derived food. Legislation is in place in many countries to ensure antimicrobial drug residue quantities are less than the maximum residue limits (MRL) defined on the basis of food safety. In this context, the recent years have witnessed a special interest in the field of electrochemical biosensors for food safety, based on their unique analytical features. This review article is focused on the recent progress in the domain of electrochemical biosensors to monitor antimicrobial drug residues in animal-derived food. PMID:28837093

New Frontiers and Challenges for Single-Cell Electrochemical Analysis.

PubMed

Zhang, Jingjing; Zhou, Junyu; Pan, Rongrong; Jiang, Dechen; Burgess, James D; Chen, Hong-Yuan

2018-02-23

Previous measurements of cell populations might obscure many important cellular differences, and new strategies for single-cell analyses are urgently needed to re-examine these fundamental biological principles for better diagnosis and treatment of diseases. Electrochemistry is a robust technique for the analysis of single living cells that has the advantages of minor interruption of cellular activity and provides the capability of high spatiotemporal resolution. The achievements of the past 30 years have revealed significant information about the exocytotic events of single cells to elucidate the mechanisms of cellular activity. Currently, the rapid developments of micro/nanofabrication and optoelectronic technologies drive the development of multifunctional electrodes and novel electrochemical approaches with higher resolution for single cells. In this Perspective, three new frontiers in this field, namely, electrochemical microscopy, intracellular analysis, and single-cell analysis in a biological system (i.e., neocortex and retina), are reviewed. The unique features and remaining challenges of these techniques are discussed.

Atomic scale deposition of Pt around Au nanoparticles to achieve much enhanced electrocatalysis of Pt

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

Xi, Zheng; Lv, Haifeng; Erdosy, Daniel P.

Here, we report an electrochemical method to deposit atomic scale Pt on a 5 nm Au nanoparticle (NP) surface in N 2-saturated 0.5 M H 2SO 4. Furthermore, Pt is provided by the Pt wire counter electrode via one-step Pt wire oxidation, dissolution, and deposition realized by controlled electrochemical scanning. Scanning from 0.6–1.0 V (vs. RHE) for 10 000 cycles gives Au 98.2Pt 1.8, which serves as an excellent catalyst for the formic acid oxidation reaction, showing 41 times higher specific activity (20.19 mA cm -2) and 25 times higher mass activity (10.80 A mg Pt -1) with much bettermore » CO-tolerance and stability than commercial Pt. This work demonstrates a unique strategy to minimize the use of Pt as a catalyst for electrochemical reactions.« less

Electrochemical Liquid Phase Epitaxy (ec-LPE): A New Methodology for the Synthesis of Crystalline Group IV Semiconductor Epifilms.

PubMed

Demuth, Joshua; Fahrenkrug, Eli; Ma, Luyao; Shodiya, Titilayo; Deitz, Julia I; Grassman, Tyler J; Maldonado, Stephen

2017-05-24

Deposition of epitaxial germanium (Ge) thin films on silicon (Si) wafers has been achieved over large areas with aqueous feedstock solutions using electrochemical liquid phase epitaxy (ec-LPE) at low temperatures (T ≤ 90 °C). The ec-LPE method uniquely blends the simplicity and control of traditional electrodeposition with the material quality of melt growth. A new electrochemical cell design based on the compression of a liquid metal electrode into a thin cavity that enables ec-LPE is described. The epitaxial nature, low strain character, and crystallographic defect content of the resultant solid Ge films were analyzed by electron backscatter diffraction, scanning transmission electron microscopy, high resolution X-ray diffraction, and electron channeling contrast imaging. The results here show the first step toward a manufacturing infrastructure for traditional crystalline inorganic semiconductor epifilms that does not require high temperature, gaseous precursors, or complex apparatus.

Highly stable aluminum-based metal-organic frameworks as biosensing platforms for assessment of food safety.

PubMed

Liu, Chun-Sen; Sun, Chun-Xiao; Tian, Jia-Yue; Wang, Zhuo-Wei; Ji, Hong-Fei; Song, Ying-Pan; Zhang, Shuai; Zhang, Zhi-Hong; He, Ling-Hao; Du, Miao

2017-05-15

Two unique immunosensors made of aluminum-based metal-organic frameworks (MOFs), namely, 515- and 516-MOFs, with 4,4',4''-nitrilotribenzoic acid (H 3 NTB) were successfully obtained to efficiently assess food safety. The as-prepared 515- and 516-MOFs exhibited superior thermal and physicochemical stability, high electrochemical activity, and good biocompatibility. Among these immunosensors, 516-MOF showed a preferable biosensing ability toward analytes determined by electrochemical techniques. The developed 516-MOF-based electrochemical biosensor not only demonstrated high sensitivity with low detection limits of 0.70 and 0.40pgmL -1 toward vomitoxin and salbutamol, respectively, but also showed good selectivity in the presence of other interferences. Therefore, with the advantages of high sensitivity, good selectivity, and simple operation, this new strategy is believed to exhibit great potential for simple and convenient detection of poisonous and harmful residues in food. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochemical sensor for rutin detection based on Au nanoparticle-loaded helical carbon nanotubes

NASA Astrophysics Data System (ADS)

Yang, Haitang; Li, Bingyue; Cui, Rongjing; Xing, Ruimin; Liu, Shanhu

2017-10-01

The key step in the fabrication of highly active electrochemical sensors is seeking multifunctional nanocomposites as electrode modified materials. In this study, the gold nanoparticle-decorated helical carbon nanotube nanocomposites (AuNPs-HCNTs) were fabricated for rutin detection because of its superior sensitivity, the chemical stability of AuNPs, and the superior conductivity and unique 3D-helical structure of helical carbon nanotubes. Results showed the prepared nanocomposites exhibited superior electrocatalytic activity towards rutin due to the synergetic effects of AuNPs and HCNTs. Under the optimized conditions, the developed sensor exhibited a linear response range from 0.1 to 31 μmol/L for rutin with a low detectable limit of 81 nmol/L. The proposed method might offer a possibility for electrochemical analysis of rutin in Chinese medical analysis or serum monitoring owing to its low cost, simplicity, high sensitivity, good stability, and few interferences against common coexisting ions in real samples.