The role of ionic liquid electrolyte in an aluminum–graphite electrochemical cell

DOE PAGES

Agiorgousis, Michael L.; Sun, Yi -Yang; Zhang, Shengbai

2017-02-17

Using first-principles calculations and molecular dynamics simulation, we study the working mechanism in an aluminum–graphite electrochemical cell, which was recently reported to exhibit attractive performance. We exclude the possibility of Al 3+ cation intercalation into graphite as in standard Li-ion batteries. Instead, we show that the AlCl 4 – anion intercalation mechanism is thermodynamically feasible. By including the ionic liquid electrolyte in the overall redox reaction, we are able to reproduce the high voltage observed in experiment. The active involvement of electrolyte in the reaction suggests that the evaluation of energy density needs to take the electrolyte into consideration. Here,more » our proposed structural model is consistent with the new peaks appearing in X-ray diffraction from the intercalation compound. The high rate capability is explained by the ultralow diffusion barriers of the AlCl 4 intercalant. With the clarified working mechanism, it becomes clear that the high voltage of the Al–graphite cell is a result of the thermodynamic instability of the AlCl 4-intercalated graphite.« less

Pillared graphite anodes for reversible sodiation.

PubMed

Zhang, Hanyang; Li, Zhifei; Xu, Wei; Chen, Yicong; Ji, Xiulei; Lerner, Michael M

2018-08-10

There has been a major effort recently to develop new rechargeable sodium-ion electrodes. In lithium ion batteries, LiC 6 forms from graphite and desolvated Li cations during the first charge. With sodium ions, graphite only shows a significant capacity when Na + intercalates as a solvated complex, resulting in ternary graphite intercalation compounds (GICs). Although this chemistry has been shown to be highly reversible and to support high rates in small test cells, these GICs can require >250% volume expansion and contraction during cycling. Here we demonstrate the first example of GICs that reversibly sodiate/desodiate without any significant volume change. These pillared GICs are obtained by electrochemical reduction of graphite in an ether/amine co-solvent electrolyte. The initial gallery expansion, 0.36 nm, is less than half of that in diglyme-based systems, and shows a similar capacity. Thermal analyses suggest the pillaring phenomenon arises from stronger co-intercalate interactions in the GIC galleries.

An enhanced hydrogen adsorption enthalpy for fluoride intercalated graphite compounds.

PubMed

Cheng, Hansong; Sha, Xianwei; Chen, Liang; Cooper, Alan C; Foo, Maw-Lin; Lau, Garret C; Bailey, Wade H; Pez, Guido P

2009-12-16

We present a combined theoretical and experimental study on H(2) physisorption in partially fluorinated graphite. This material, first predicted computationally using ab initio molecular dynamics simulation and subsequently synthesized and characterized experimentally, represents a novel class of "acceptor type" graphite intercalated compounds that exhibit significantly higher isosteric heat of adsorption for H(2) at near ambient temperatures than previously demonstrated for commonly available porous carbon-based materials. The unusually strong interaction arises from the semi-ionic nature of the C-F bonds. Although a high H(2) storage capacity (>4 wt %) at room temperature is predicted not to be feasible due to the low heat of adsorption, enhanced storage properties can be envisaged by doping the graphitic host with appropriate species to promote higher levels of charge transfer from graphene to F(-) anions.

The 13C nuclear magnetic resonance in graphite intercalation compounds

NASA Technical Reports Server (NTRS)

Tsang, T.; Resing, H. A.

1985-01-01

The (13)C NMR chemical shifts of graphite intercalation compounds were calculated. For acceptor types, the shifts come mainly from the paramagnetic (Ramsey) intra-atomic terms. They are related to the gross features of the two-dimensional band structures. The calculated anisotropy is about -140 ppm and is independent of the finer details such as charge transfer. For donor types, the carbon 2p pi orbitals are spin-polarized because of mixing with metal conduction electrons, thus there is an additional dipolar contribution which may be correlated with the electronic specific heat. The general agreement with experimental data is satisfactory.

C-13 nuclear magnetic resonance in graphite intercalation compounds

NASA Technical Reports Server (NTRS)

Tsang, T.; Resing, H. A.

1985-01-01

The C-13 NMR chemical shifts of graphite intercalation compounds have been calculated. For acceptor types, the shifts come mainly from the paramagnetic (Ramsey) intra-atomic terms. They are related to the gross features of the two-dimensional band structures. The calculated anisotropy is about - 140 ppm and is independent of the finer details such as charge transfer. For donor types, the carbon 2p pi orbitals are spin-polarized because of mixing with metal-conduction electrons, thus there is an additional dipolar contribution which may be correlated with the electronic specific heat. The general agreement with experimental data is satisfactory.

Stability of bromine, iodine monochloride, copper (II) chloride, and nickel (II) chloride intercalated pitch-based graphite fibers

NASA Technical Reports Server (NTRS)

Gaier, James R.; Slabe, Melissa E.; Shaffer, Nanette

1987-01-01

Four different grades of pitch-based graphite fibers (Amoco P-55, P-75, P-100. and P-120) were intercalated with each of four different intercalates: bromine (Br2), iodine monochloride (ICl), copper (II) chloride (CuCl2), and nickel (II) chloride (NiCl2). The P-55 fibers did not react with Br2 or NiCl2, and the P-75 did not react with NiCl2. The stability of the electrical resistance of the intercalated fibers was monitored over long periods of time in ambient, high humidity (100 percent at 60 C), vacuum (10 to the -6 torr), and high temperature (up to 400 C) conditions. Fibers with lower graphitization form graphite intercalation compounds (GIC's) which are more stable than those with higher graphitization (i.e., P-55 (most stable) greater than P-75 greater than P-100 greater than P-120 (least stable). Br2 formed the most stable GIC's followed in order of decreasing stability by ICl, CuCl2, and NiCl2. While Br2 GIC's had the most stability, ICl had the advantages of forming GIC's with slightly greater reduction in resistance (by about 10%) than Br2, and the ability to intercalate P-55 fiber. Transition metal chlorides are susceptible to water vapor and high temperature. The stability of fibers in composites differs.

Superconductivity in Li{sub 3}Ca{sub 2}C{sub 6} intercalated graphite

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

Emery, Nicolas; Herold, Claire; Mareche, Jean-Francois

2006-04-15

In this paper, we report the discovery of superconductivity in Li{sub 3}Ca{sub 2}C{sub 6}. Several graphite intercalation compounds (GICs) with electron donors, are well known as superconductors [T. Enoki, S. Masatsugu, E. Morinobu, Graphite Intercalation Compounds and Applications, Oxford University Press, Oxford, 2003]. It is probably not astonishing, since it is generally admitted that low dimensionality promotes high superconducting transition temperatures. Superconductivity is lacking in pristine graphite, but after charging the graphene planes by intercalation, its electronic properties change considerably and superconducting behaviour can appear. Li{sub 3}Ca{sub 2}C{sub 6} is a ternary GIC [S. Pruvost, C. Herold, A. Herold, P.more » Lagrange, Eur. J. Inorg. Chem. 8 (2004) 1661-1667], for which the intercalated sheets are very thick and poly layered (five lithium layers and two calcium ones). It contains a great amount of metal (five metallic atoms for six carbon ones). Its critical temperature of 11.15 K is very close to that of CaC{sub 6} GIC [T.E. Weller, M. Ellerby, S.S. Saxena, R.P. Smith, N.T. Skipper, Nat. Phys. 1 (2005) 39-41; N. Emery, C. Herold, M. d'Astuto, V. Garcia, Ch. Bellin, J.F. Mareche, P. Lagrange, G. Loupias, Phys. Rev. Lett. 95 (2005) 087003] (11.5 K). Both CaC{sub 6} and Li{sub 3}Ca{sub 2}C{sub 6} GICs possess currently the highest transition temperatures among all the GICs.« less

Synthesis and electrical characterization of magnetic bilayer graphene intercalate.

PubMed

Kim, Namdong; Kim, Kwang S; Jung, Naeyoung; Brus, Louis; Kim, Philip

2011-02-09

We report synthesis and transport properties of the minimal graphite intercalation compound, a ferric chloride (FeCl(3))(n) island monolayer inside bilayer graphene. Chemical doping by the intercalant is simultaneously probed by micro-Raman spectroscopy and Hall measurements. Quantum oscillations of conductivity originate from microscopic domains of intercalated and unintercalated regions. A slight upturn in resistance related to magnetic transition is observed. Two-dimensional intercalation in bilayer graphene opens new possibilities to engineer two-dimensional properties of intercalates.

Indirect measurement of N-14 quadrupolar coupling for NH3 intercalated in potassium graphite

NASA Technical Reports Server (NTRS)

Tsang, T.; Fronko, R. M.; Resing, H. A.

1987-01-01

A method for indirect measurement of the nuclear quadrupolar coupling was developed and applied to NH3 molecules in the graphite intercalation compound K(NH3)4.3C24, which has a layered structure with alternating carbon and intercalant layers. Three triplets were observed in the H-1 NMR spectra of the compound. The value of the N-14 quadrupolar coupling constant of NH3 (3.7 MHz), determined indirectly from the H-1 NMR spectra, was intermediate between the gas value of 4.1 MHz and the solid-state value of 3.2 MHz. The method was also used to deduce the (H-1)-(H-1) and (N-14)-(H-1) dipolar interactions, the H-1 chemical shifts, and the molecular orientations and motions of NH3.

Structural and Kinetic Properties of Graphite Intercalation Compounds

DTIC Science & Technology

1983-04-29

The exfoliation of graphite-FeCl 3NH has been used for making blankets for the extinction of metal fires [12). In addition. exfoliated graphite is...FeCl3-oH3 has been used (Aerotech GCma, 0.5 MHz wideband) equipped with for making blankets for the extinction of metal fires (3). In addition

Highly Conducting Graphite Epoxy Composite Demonstrated

NASA Technical Reports Server (NTRS)

Gaier, James R.

1999-01-01

Weight savings as high as 80 percent could be achieved if graphite polymer composites could replace aluminum in structures such as electromagnetic interference shielding covers and grounding planes. This could result in significant cost savings, especially for the mobile electronics found in spacecraft, aircraft, automobiles, and hand-held consumer electronics. However, such composites had not yet been fabricated with conductivity sufficient to enable these applications. To address this lack, a partnership of the NASA Lewis Research Center, Manchester College, and Applied Sciences, Inc., fabricated nonmetallic composites with unprecedented electrical conductivity. For these composites, heat-treated, vapor-grown graphite fibers were selected which have a resistivity of about 80 mW-cm, more than 20 times more conductive than typical carbon fibers. These fibers were then intercalated with iodine bromide (IBr). Intercalation is the insertion of guest atoms or molecules between the carbon planes of the graphite fibers. Since the carbon planes are not highly distorted in the process, intercalation has little effect on mechanical and thermal properties. Intercalation does, however, lower the carbon fiber resistivity to less than 10 mW-cm, which is comparable to that of metal fibers. Scaleup of the reaction was required since the initial intercalation experiments would be carried out on 20-mg quantities of fibers, and tens of grams of intercalated fibers would be needed to fabricate even small demonstration composites. The reaction was first optimized through a time and temperature study that yielded fibers with a resistivity of 8.7 2 mW-cm when exposed to IBr vapor at 114 C for 24 hours. Stability studies indicated that the intercalated fibers rapidly lost their conductivity when exposed to temperatures as low as 40 C in air. They were not, however, susceptible to degradation by water vapor in the manner of most graphite intercalation compounds. The 1000-fold scaleup experiments concluded that 114 C was near the optimum temperature, but that the intercalation time needed to be lengthened by a factor of 3.

Superconductivity in graphite intercalation compounds

DOE PAGES

Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; ...

2015-02-26

This study examines the field of superconductivity in the class of materials known as graphite intercalation compounds which has a history dating back to the 1960s. This paper recontextualizes the field in light of the discovery of superconductivity in CaC₆ and YbC₆ in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic statesmore » and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.« less

Physicochemical characterization, and relaxometry studies of micro-graphite oxide, graphene nanoplatelets, and nanoribbons.

PubMed

Paratala, Bhavna S; Jacobson, Barry D; Kanakia, Shruti; Francis, Leonard Deepak; Sitharaman, Balaji

2012-01-01

The chemistry of high-performance magnetic resonance imaging contrast agents remains an active area of research. In this work, we demonstrate that the potassium permanganate-based oxidative chemical procedures used to synthesize graphite oxide or graphene nanoparticles leads to the confinement (intercalation) of trace amounts of Mn(2+) ions between the graphene sheets, and that these manganese intercalated graphitic and graphene structures show disparate structural, chemical and magnetic properties, and high relaxivity (up to 2 order) and distinctly different nuclear magnetic resonance dispersion profiles compared to paramagnetic chelate compounds. The results taken together with other published reports on confinement of paramagnetic metal ions within single-walled carbon nanotubes (a rolled up graphene sheet) show that confinement (encapsulation or intercalation) of paramagnetic metal ions within graphene sheets, and not the size, shape or architecture of the graphitic carbon particles is the key determinant for increasing relaxivity, and thus, identifies nano confinement of paramagnetic ions as novel general strategy to develop paramagnetic metal-ion graphitic-carbon complexes as high relaxivity MRI contrast agents.

Physicochemical Characterization, and Relaxometry Studies of Micro-Graphite Oxide, Graphene Nanoplatelets, and Nanoribbons

PubMed Central

Paratala, Bhavna S.; Jacobson, Barry D.; Kanakia, Shruti; Francis, Leonard Deepak; Sitharaman, Balaji

2012-01-01

The chemistry of high-performance magnetic resonance imaging contrast agents remains an active area of research. In this work, we demonstrate that the potassium permanganate-based oxidative chemical procedures used to synthesize graphite oxide or graphene nanoparticles leads to the confinement (intercalation) of trace amounts of Mn2+ ions between the graphene sheets, and that these manganese intercalated graphitic and graphene structures show disparate structural, chemical and magnetic properties, and high relaxivity (up to 2 order) and distinctly different nuclear magnetic resonance dispersion profiles compared to paramagnetic chelate compounds. The results taken together with other published reports on confinement of paramagnetic metal ions within single-walled carbon nanotubes (a rolled up graphene sheet) show that confinement (encapsulation or intercalation) of paramagnetic metal ions within graphene sheets, and not the size, shape or architecture of the graphitic carbon particles is the key determinant for increasing relaxivity, and thus, identifies nano confinement of paramagnetic ions as novel general strategy to develop paramagnetic metal-ion graphitic-carbon complexes as high relaxivity MRI contrast agents. PMID:22685555

Disclinations in Carbon-Carbon Composites.

DTIC Science & Technology

1983-09-01

8i-C-0641 U LASIFIED F/6G ii/4 N I uuuuullu ..D un n ." =25 1321. MICROCOP EOUINTSLHR NATONL = BUR A FSADRS16- UNCLASSI FI ED SECURITY CLASIrICA’sJM...Applications nuclear carbon carbon fiber intercalation compounds biocarbons and potential uses - Fundamentals physics chemistry technology The technical...Graphite intercalation compounds : old and new University of Munich problems in the chemist’s view West Germany L. S. Singer Carbon fibers from mesophase

Superlattice Effects in Graphite Intercalation Compounds.

DTIC Science & Technology

1986-04-15

away from ;le[ Isy.st,.mns (r lin( nl :; atars ) and look for nonlinear dynamical effects -. m,,5,: U~ i,: ,1 : s y’t, rns, a3iioh m i Josephson...Intercalation Coaanm, Chemistry Dept., Northeast(.rn,, February 25, 1935. ( iv) "Giant Magnetic Interaction and Domain Dynamics in Twe -. "Dimensions," hoston

Method of producing nano-scaled graphene and inorganic platelets and their nanocomposites

DOEpatents

Jang, Bor Z [Centerville, OH; Zhamu, Aruna [Centerville, OH

2011-02-22

Disclosed is a method of exfoliating a layered material (e.g., graphite and graphite oxide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm, and often between 0.34 nm and 1.02 nm. The method comprises: (a) subjecting the layered material in a powder form to a halogen vapor at a first temperature above the melting point or sublimation point of the halogen at a sufficient vapor pressure and for a duration of time sufficient to cause the halogen molecules to penetrate an interlayer space of the layered material, forming a stable halogen-intercalated compound; and (b) heating the halogen-intercalated compound at a second temperature above the boiling point of the halogen, allowing halogen atoms or molecules residing in the interlayer space to exfoliate the layered material to produce the platelets. Alternatively, rather than heating, step (a) is followed by a step of dispersing the halogen-intercalated compound in a liquid medium which is subjected to ultrasonication for exfoliating the halogen-intercalated compound to produce the platelets, which are dispersed in the liquid medium. The halogen can be readily captured and re-used, thereby significantly reducing the impact of halogen to the environment. The method can further include a step of dispersing the platelets in a polymer or monomer solution or suspension as a precursor step to nanocomposite fabrication.

Method of producing nano-scaled graphene and inorganic platelets and their nanocomposites

DOEpatents

Jang, Bor Z [Centerville, OH; Zhamu, Aruna [Centerville, OH

2012-02-14

Disclosed is a method of exfoliating a layered material (e.g., graphite and graphite oxide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm, and often between 0.34 nm and 1.02 nm. The method comprises: (a) subjecting the layered material in a powder form to a halogen vapor at a first temperature above the melting point or sublimation point of the halogen at a sufficient vapor pressure and for a duration of time sufficient to cause the halogen molecules to penetrate an interlayer space of the layered material, forming a stable halogen-intercalated compound; and (b) heating the halogen-intercalated compound at a second temperature above the boiling point of the halogen, allowing halogen atoms or molecules residing in the interlayer space to exfoliate the layered material to produce the platelets. Alternatively, rather than heating, step (a) is followed by a step of dispersing the halogen-intercalated compound in a liquid medium which is subjected to ultrasonication for exfoliating the halogen-intercalated compound to produce the platelets, which are dispersed in the liquid medium. The halogen can be readily captured and re-used, thereby significantly reducing the impact of halogen to the environment. The method can further include a step of dispersing the platelets in a polymer or monomer solution or suspension as a precursor step to nanocomposite fabrication.

Graphite intercalation compound with iodine as the major intercalate

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh; Kucera, Donald

1994-01-01

Halogenated graphite CBr(x)I(y) (I less than y/x less than 10) was made by exposing graphite materials to either pure Br2 or an I2/Br2/HBr mixture to initiate the reaction, and then to iodine vapor containing a small amount of Br2/HBr/IBr to complete the intercalation reaction. Wetting of the graphite materials by the I2/Br2/HBr mixture is needed to start the reaction, and a small amount of Br2/HBr/IBr is needed to complete the charge transfer between iodine and carbon. The interplanar spacings for the graphite materials need to be in the 3.35 to 3.41 A range. The X-ray diffraction data obtained from the halogenated HOPG indicate that the distance between the two carbon layers containing intercalate is 7.25 A. Electrical resistivity of the fiber product is from 3 to 6.5 times the pristine value, The presence of a small amount of isoprene rubber in the reaction significantly increased the iodine-to-bromine ratio in the product. In this reaction, rubber is known to generate HBr and to slowly remove bromine from the vapor. The halogenation generally caused a 22 percent to 25 percent weight increase. The halogens were found uniformly distributed in the product interior. However, although the surface contains very little iodine, it has high concentrations of bromine and oxygen. It is believed that the high concentrations of bromine and oxygen in this surface cause the halogenated fiber to be more resistant to structural damage during subsequent fluorination to fabricate graphite fluoride fibers.

Multiphoton luminescent graphene quantum dots for in vivo tracking of human adipose-derived stem cells

NASA Astrophysics Data System (ADS)

Kim, Jin; Song, Sung Ho; Jin, Yoonhee; Park, Hyun-Ji; Yoon, Hyewon; Jeon, Seokwoo; Cho, Seung-Woo

2016-04-01

The applicability of graphene quantum dots (GQDs) for the in vitro and in vivo live imaging and tracking of different types of human stem cells is investigated. GQDs synthesized by the modified graphite intercalated compound method show efficient cellular uptake with improved biocompatibility and highly sensitive optical properties, indicating their feasibility as a bio-imaging probe for stem cell therapy.The applicability of graphene quantum dots (GQDs) for the in vitro and in vivo live imaging and tracking of different types of human stem cells is investigated. GQDs synthesized by the modified graphite intercalated compound method show efficient cellular uptake with improved biocompatibility and highly sensitive optical properties, indicating their feasibility as a bio-imaging probe for stem cell therapy. Electronic supplementary information (ESI) available: Additional results. See DOI: 10.1039/c6nr02143c

Recent Progress in Graphite Intercalation Compounds for Rechargeable Metal (Li, Na, K, Al)-Ion Batteries.

PubMed

Xu, Jiantie; Dou, Yuhai; Wei, Zengxi; Ma, Jianmin; Deng, Yonghong; Li, Yutao; Liu, Huakun; Dou, Shixue

2017-10-01

Lithium-ion batteries (LIBs) with higher energy density are very necessary to meet the increasing demand for devices with better performance. With the commercial success of lithiated graphite, other graphite intercalation compounds (GICs) have also been intensively reported, not only for LIBs, but also for other metal (Na, K, Al) ion batteries. In this Progress Report, we briefly review the application of GICs as anodes and cathodes in metal (Li, Na, K, Al) ion batteries. After a brief introduction on the development history of GICs, the electrochemistry of cationic GICs and anionic GICs is summarized. We further briefly summarize the use of cationic GICs and anionic GICs in alkali ion batteries and the use of anionic GICs in aluminium-ion batteries. Finally, we reach some conclusions on the drawbacks, major progress, emerging challenges, and some perspectives on the development of GICs for metal (Li, Na, K, Al) ion batteries. Further development of GICs for metal (Li, Na, K, Al) ion batteries is not only a strong supplement to the commercialized success of lithiated-graphite for LIBs, but also an effective strategy to develop diverse high-energy batteries for stationary energy storage in the future.

Recent Progress in Graphite Intercalation Compounds for Rechargeable Metal (Li, Na, K, Al)‐Ion Batteries

PubMed Central

Xu, Jiantie; Dou, Yuhai; Wei, Zengxi; Li, Yutao; Liu, Huakun; Dou, Shixue

2017-01-01

Abstract Lithium‐ion batteries (LIBs) with higher energy density are very necessary to meet the increasing demand for devices with better performance. With the commercial success of lithiated graphite, other graphite intercalation compounds (GICs) have also been intensively reported, not only for LIBs, but also for other metal (Na, K, Al) ion batteries. In this Progress Report, we briefly review the application of GICs as anodes and cathodes in metal (Li, Na, K, Al) ion batteries. After a brief introduction on the development history of GICs, the electrochemistry of cationic GICs and anionic GICs is summarized. We further briefly summarize the use of cationic GICs and anionic GICs in alkali ion batteries and the use of anionic GICs in aluminium‐ion batteries. Finally, we reach some conclusions on the drawbacks, major progress, emerging challenges, and some perspectives on the development of GICs for metal (Li, Na, K, Al) ion batteries. Further development of GICs for metal (Li, Na, K, Al) ion batteries is not only a strong supplement to the commercialized success of lithiated‐graphite for LIBs, but also an effective strategy to develop diverse high‐energy batteries for stationary energy storage in the future. PMID:29051856

A method to remove intercalates from bromine and iodine intercalated carbon fibers

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh

1993-01-01

Upon exposure to room-temperature fluorine, intercalated carbon fibers (containing either bromine alone or iodine and bromine together) become heavier and less stable. For Amoco P-100 graphitized carbon fibers which were intercalated with 18 percent bromine by weight, 1 hr of fluorine exposure results in a large weight increase, but causes only a small decrease in thermal stability. More than l hr of fluorine exposure time results in small additional increases in fiber weight, but significant further decreases in fiber thermal stability. Such phenomena do not occur if the fluorine exposure is at 250 C. These observations suggest the mechanism that at room temperature, fluorine is absorbed quickly by the intercalated fibers and intercalated slowly into the fibers. Most of the original intercalates are replaced by fluorine in the process of fluorine intercalation. Under an inert environment, the bromine intercalated fibers are much more thermally stable. After 800 C vacuum heating for two weeks, the brominated fibers lost about 45 percent of their bromine, and their resistivity increased from 64 omega-cm to a range of 95 to 170 micro omega-cm. This is still much lower than the 300 micro omega-cm value for pristine P-100. For practical purposes, in order to preserve their thermal stability, brominated fibers need to be protected from exposure to fluorine at room temperature, or to any intercalate at a temperature where, upon direct contact to graphite, an intercalation compound can easily be formed.

Room-Temperature Fluorine-Induced Decrease in the Stability of Bromine and Iodine Intercalated Carbon Fibers

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh

1995-01-01

Upon exposure to room-temperature fluorine, intercalated carbon fibers (containing either bromine alone or iodine and bromine together) become heavier and less stable. For Amoco P-100 graphitized carbon fibers, which were intercalated with 18 wt percent bromine, 1 hour of fluorine exposure resulted in a large weight increase but caused only a small decrease in thermal stability. An additional 89 hours of fluorine exposure time resulted in small additional increases in fiber weight, but significant further decreases in fiber thermal stability. Such phenomena of weight increase and stability decrease do not occur if the intercalated fibers are exposed to 250 C fluorine. These observations suggest that, at room temperature, fluorine is absorbed quickly by the intercalated fibers and is intercalated slowly into the fibers. Most of the original intercalates are replaced by fluorine in the process of fluorine intercalation. In an inert environment, the bromine intercalated fibers are much more thermally stable. After 800 C vacuum heating for 2 weeks, the brominated fibers lost about 45% of their bromine, and their resistivity increased from 64 mu(Omega)-cm to a range of 95-170 mu(Omega)-cm. This is still much lower than the value of 300 mu(Omega)-cm for pristine P-100. For practical purposes, to preserve their thermal stability, brominated fibers need to be protected from exposure to fluorine at room temperature or to any intercalate at a temperature where, upon direct contact with graphite, an intercalation compound can easily be formed.

Comparison of fluoride intercalation/de-intercalation processes on graphite electrodes in aqueous and aqueous methanolic HF media

NASA Astrophysics Data System (ADS)

Noel, M.; Santhanam, R.; Francisca Flora, M.

The solvent can play a major role in the intercalation/de-intercalation process and the stability of graphite substrates towards this process. This fact is established in the present work that involves fluoride intercalation/de-intercatlation on graphite electrodes in aqueous and aqueous methanolic HF solutions where the HF concentration is varied between 1.0 and 18.0 M. In addition to cyclic voltammetry and potentiostatic polarization, open-circuit potential decay measurements, scanning electron microscopy and X-ray diffraction measurements have been employed. In general, addition of methanol and increasing concentration of HF raise the overall intercalation/de-intercalation efficiency. Methanol is adsorbed preferentially on the graphite lattice and, hence, suppresses both oxygen evolution and the formation of passive graphite oxides. In 15.0 M HF, the optimum methanol concentration is 5 vol.%. This suggests that, in addition to the adsorption effect, there is some weakening of the structured water molecules that facilitates the solvated fluoride ions for efficient intercalation.

Effect of friction on oxidative graphite intercalation and high-quality graphene formation.

PubMed

Seiler, Steffen; Halbig, Christian E; Grote, Fabian; Rietsch, Philipp; Börrnert, Felix; Kaiser, Ute; Meyer, Bernd; Eigler, Siegfried

2018-02-26

Oxidative wet-chemical delamination of graphene from graphite is expected to become a scalable production method. However, the formation process of the intermediate stage-1 graphite sulfate by sulfuric acid intercalation and its subsequent oxidation are poorly understood and lattice defect formation must be avoided. Here, we demonstrate film formation of micrometer-sized graphene flakes with lattice defects down to 0.02% and visualize the carbon lattice by transmission electron microscopy at atomic resolution. Interestingly, we find that only well-ordered, highly crystalline graphite delaminates into oxo-functionalized graphene, whereas other graphite grades do not form a proper stage-1 intercalate and revert back to graphite upon hydrolysis. Ab initio molecular dynamics simulations show that ideal stacking and electronic oxidation of the graphite layers significantly reduce the friction of the moving sulfuric acid molecules, thereby facilitating intercalation. Furthermore, the evaluation of the stability of oxo-species in graphite sulfate supports an oxidation mechanism that obviates intercalation of the oxidant.

Fundamental Electronic Properties of Donor-Type Graphite Intercalated Compounds.

DTIC Science & Technology

1984-08-01

charge distribution for 2nd and 3rd stage Li-graphite. Our results showed that, in fact , the major part of the transferred charge is concentrated in the...the fact "melting" would be a continuous loss of c-axis corre- that the same exponent fits the data in the range latlons, which would broaden the (100...all cases. The fact that the I! sublattice is not entirely decoupled from closest approach to agreement is between the RS data the graphite network at

Graphite fiber intercalation: Dynamics of the bromine intercalation process

NASA Technical Reports Server (NTRS)

Jaworske, D. A.; Zinolabedini, R.

1985-01-01

The resistance of pitch-based graphite fibers was monitored, in situ, during a series of bromine intercalation experiments. The threshold pressure for the bromine intercalation of pitch-based fibers was estimated to be 102 torr. When the bromine atmosphere was removed from the reaction chamber, the resistivity of the intercalated graphite fibers increased consistently. This increase was attributed to loss of bromine from the perimeter of the fiber. The loss was confirmed by mapping the bromine concentration across the diameter of single intercalated fibers with either energy dispersive spectroscopy or scanning Auger microscopy. A statistical study comparing fibers intercalated in bromine vapor with fibers intercalated in bromine liquid showed that similar products were obtained with both methods of intercalation.

Self-Activating, Capacitive Anion Intercalation Enables High-Power Graphite Cathodes.

PubMed

Wang, Gang; Yu, Minghao; Wang, Jungang; Li, Debao; Tan, Deming; Löffler, Markus; Zhuang, Xiaodong; Müllen, Klaus; Feng, Xinliang

2018-05-01

Developing high-power cathodes is crucial to construct next-generation quick-charge batteries for electric transportation and grid applications. However, this mainly relies on nanoengineering strategies at the expense of low scalability and high battery cost. Another option is provided herein to build high-power cathodes by exploiting inexpensive bulk graphite as the active electrode material, where anion intercalation is involved. With the assistance of a strong alginate binder, the disintegration problem of graphite cathodes due to the large volume variation of >130% is well suppressed, making it possible to investigate the intrinsic electrochemical behavior and to elucidate the charge storage kinetics of graphite cathodes. Ultrahigh power capability up to 42.9 kW kg -1 at the energy density of >300 Wh kg -1 (based on graphite mass) and long cycling life over 10 000 cycles are achieved, much higher than those of conventional cathode materials for Li-ion batteries. A self-activating and capacitive anion intercalation into graphite is discovered for the first time, making graphite a new intrinsic intercalation-pseudocapacitance cathode material. The finding highlights the kinetical difference of anion intercalation (as cathode) from cation intercalation (as anode) into graphitic carbon materials, and new high-power energy storage devices will be inspired. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metallic conductivity and air stability in copper chloride intercalated carbon fibers

NASA Astrophysics Data System (ADS)

Oshima, H.; Woollam, J. A.; Yavrouian, A.

1982-12-01

Carbon-copper chloride intercalation compounds have been obtained by using variously graphitized carbon fibers as host materials. The resultant conductors are air stable, thermally stable to 450 K, have electrical resistivities as low as 12.9 microohm cm at room temperature, and have metallic conductivity temperature dependencies. These intercalated fibers have tensile strengths of 160000 psi, and Young's moduli of 25 x 10 to the 6th psi. For aerospace use, 1/(resistivity x density) is a figure of merit. On this basis, a reduction in resistivity by a factor of two will make this conductor competitive with copper.

Electrochemical exfoliation of graphite to stage-III graphite bisulfate flakes in low concentration sulfuric acid solution: A novel synthesis route to completely trilayer graphene suspension

NASA Astrophysics Data System (ADS)

Mir, Afkham; Shukla, Anupam

2018-06-01

Graphene produced from electrochemical exfoliation of graphite show a scatter in the number of layers. This scatter is a serious drawback for sensor and opto-electronic applications since the electronic properties of graphene change with number of layers. The scatter in the layer number of graphene is caused by formation of the intermediate graphite intercalation compounds (GIC) of different stage numbers as well as simultaneous cleaving of the GICs in the dispersion-unsuitable aqueous environment. In this work, we show the synthesis of stage-III graphite bisulfate (GB) enriched flakes by electrochemical exfoliation of graphite in low concentration (0.1 M) sulfuric acid from two different routes. We further show that the intercalated bisulfate planes provide sites for selective cleaving of the GB particles to trilayer graphene in DMF, a solvent favorable for graphene dispersion. Morphological characterizations show that while GB particles from one of the routes give graphene with a small scatter in the layer numbers, the other route provides a completely trilayer graphene dispersion. TEM and optical micrographs show graphene flakes have linear dimensions of several micrometers and a low aspect ratio suitable for use in sensor applications.

Reversible formation of ammonium persulfate/sulfuric acid graphite intercalation compounds and their peculiar Raman spectra.

PubMed

Dimiev, Ayrat M; Bachilo, Sergei M; Saito, Riichiro; Tour, James M

2012-09-25

Graphite intercalation compounds (GICs) can be considered stacks of individual doped graphene layers. Here we demonstrate a reversible formation of sulfuric acid-based GICs using ammonium persulfate as the chemical oxidizing agent. No covalent chemical oxidation leading to the formation of graphite oxide occurs, which inevitably happens when other compounds such as potassium permanganate are used to charge carbon layers. The resulting acid/persulfate-induced stage-1 and stage-2 GICs are characterized by suppression of the 2D band in the Raman spectra and by unusually strong enhancement of the G band. The G band is selectively enhanced at different doping levels with different excitations. These observations are in line with recent reports for chemically doped and gate-modulated graphene and support newly proposed theories of Raman processes. At the same time GICs have some advantageous differences over graphene, which are demonstrated in this report. Our experimental observations, along with earlier reported data, suggest that at high doping levels the G band cannot be used as the reference peak for normalizing Raman spectra, which is a commonly used practice today. A Fermi energy shift of 1.20-1.25 eV and ∼1.0 eV was estimated for the stage-1 and stage-2 GICs, respectively, from the Raman and optical spectroscopy data.

Electronic and Structural Studies of Intercalated Graphite and Buckminsterfullerene.

NASA Astrophysics Data System (ADS)

Kelty, Stephen Paul

Under the direction of Prof. C. M. Lieber, the surface electronic and structural properties of binary MC_{rm x} and ternary rm MM^' C_{x } donor graphite intercalation compounds (GICs) were investigated using scanning tunneling microscopy (STM) and other surface sensitive techniques. The STM images revealed previously unobserved superstructures in the local density of states contours. These new superstructures include a commensurate 4.9 A periodicity (MC_8, where M = Li, K, Rb, Cs, KHg, rm K_2Hg_2 and rm K_2Tl _3). This superstructure has been interpreted as a modulation of the surface density of states due to the underlying commensurate intercalate lattice. Other GICs exhibit longer wavelength incommensurate superstructures, including: 19 A rm (KH_{0.8}C _8), 12 A rm (KH_{0.8 }C_4), 8.9 A rm (KHgC _4) and 7.5 A rm (KTl_ {1.5}C_8) periodicities. The direct -space wavelength of these incommensurate superstructures was found to scale inversely with the amount of charge transferred from the intercalate to the graphite layers. Such a correlation is consistent with the wavelength dependence on Fermi surface expansion of a charge density wave (CDW) state. STM investigations of adsorbed films of colloidal BiI_3, prepared by a solution-phase method, revealed the presence of mono-disperse 10-50 A single-layer particles with atomic resolution. This investigation demonstrated both the validity of the preparative method for the BiI_3 particles and the capability of the STM to atomically resolve small semiconducting particles. The structural and superconducting properties of alkali metal intercalated Buckminsterfullerene (C _{60}) were also investigated. A new preparatory method was developed using heavy metal alloys instead of pure alkali metal. Using these alloys, it was discovered that high superconducting fraction intercalation compounds could be prepared under milder conditions than by using the pure alkali metal. In addition, intercalation of Hg, Tl and Bi alloys of Cs was found to form a superconducting phase which has never been prepared by direct intercalation of Cs metal. Finally, other investigators have empirically derived a linear dependence of T_{ rm c} on lattice constant for intercalated C_{60}. This dependence has been used to model the electron pairing mechanism for the superconducting state. Investigations presented herein indicate that for lattice constants greater than 14.5 A, no further increases in T_{rm c} are observed. This finding places constraints on the above mentioned electron pairing models.

Powder, paper and foam of few-layer graphene prepared in high yield by electrochemical intercalation exfoliation of expanded graphite.

PubMed

Wu, Liqiong; Li, Weiwei; Li, Peng; Liao, Shutian; Qiu, Shengqiang; Chen, Mingliang; Guo, Yufen; Li, Qi; Zhu, Chao; Liu, Liwei

2014-04-09

A facile and high-yield approach to the preparation of few-layer graphene (FLG) by electrochemical intercalation exfoliation (EIE) of expanded graphite in sulfuric acid electrolyte is reported. Stage-1 H2SO4-graphite intercalation compound is used as a key intermediate in EIE to realize the efficient exfoliation. The yield of the FLG sheets (<7 layers) with large lateral sizes (tens of microns) is more than 75% relative to the total amount of starting expanded graphite. A low degree of oxygen functionalization existing in the prepared FLG flakes enables them to disperse effectively, which contributes to the film-forming characteristics of the FLG flakes. These electrochemically exfoliated FLG flakes are integrated into several kinds of macroscopic graphene structures. Flexible and freestanding graphene papers made of the FLG flakes retain excellent conductivity (≈24,500 S m(-1)). Three-dimensional (3D) graphene foams with light weight are fabricated from the FLG flakes by the use of Ni foams as self-sacrifice templates. Furthermore, 3D graphene/Ni foams without any binders, which are used as supercapacitor electrodes in aqueous electrolyte, provide the specific capacitance of 113.2 F g(-1) at a current density of 0.5 A g(-1), retaining 90% capacitance after 1000 cycles. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A comparative study of graphite electrodes using the co-intercalation phenomenon for rechargeable Li, Na and K batteries.

PubMed

Kim, Haegyeom; Yoon, Gabin; Lim, Kyungmi; Kang, Kisuk

2016-10-18

Here, we demonstrate that graphite can serve as a versatile electrode for various rechargeable battery types by reversibly accommodating solvated alkali ions (such as K, Na, and Li) through co-intercalation in its galleries. The co-intercalation of alkali ions is observed to occur via staging reactions. Notably, their insertion behaviors, including their specific capacity, are remarkably similar regardless of the alkali ion species despite the different solubility limits of K, Na, and Li ions in graphite. Nevertheless, the insertion potentials of the solvated alkali ions differ from each other and are observed to be correlated with the interlayer distance in the intercalated graphite gallery.

A micrographic and gravimetric study of intercalation and deintercalation of graphite fibers

NASA Technical Reports Server (NTRS)

Hung, C. C.

1985-01-01

Intercalation and deintercalation of Union Carbide P-100 graphite fibers with liquid and vaporous bromine was studied gravimetrically and microscopically. The mass of the bromine intercalated fibers was found to be 17 to 20 percent greater than their pristine counterpart. This variation decreased to 17 to 18 percent after heating in air for 3 days at 200 C and to 14.5 to 18 percent after 6 days of 260 C heating. The fiber length did not change throughout the experiment. The fiber diameter increased during intercalation and decreased slightly upon deintercalation but was not affected by heating to 260 C for 3 days in air. Comparing the mass and volume data to those with highly oriented pyrolitic graphite or natural single crystal graphite suggested the possibility that the intercalated P-100 fibers could be mostly stage 4.

Effect of lightning strike on bromine intercalated graphite fiber/epoxy composites

NASA Technical Reports Server (NTRS)

Gaier, James R.; Slabe, Melissa E.; Brink, Norman O.

1991-01-01

Laminar composites were fabricated from pristine and bromine intercalated pitch based graphite fibers. It was found that laminar composites could be fabricated using either pristine or intercalated graphite fibers using standard fabrication techniques. The intercalated graphite fiber composites had electrical properties which were markedly improved over both the corresponding pitch based and polyacrylonitrile (PAN) based composites. Despite composites resistivities more than an order of magnitude lower for pitch based fiber composites, the lightning strike resistance was poorer than that of the Pan based fiber composites. This leads to the conclusion that the mechanical properties of the pitch fibers are more important than electrical or thermal properties in determining the lightning strike resistance. Based on indicated lightning strike tolerance for high elongation to failure materials, the use of vapor grown, rather than pitch based graphite fibers appears promising.

A rechargeable iodine-carbon battery that exploits ion intercalation and iodine redox chemistry.

PubMed

Lu, Ke; Hu, Ziyu; Ma, Jizhen; Ma, Houyi; Dai, Liming; Zhang, Jintao

2017-09-13

Graphitic carbons have been used as conductive supports for developing rechargeable batteries. However, the classic ion intercalation in graphitic carbon has yet to be coupled with extrinsic redox reactions to develop rechargeable batteries. Herein, we demonstrate the preparation of a free-standing, flexible nitrogen and phosphorus co-doped hierarchically porous graphitic carbon for iodine loading by pyrolysis of polyaniline coated cellulose wiper. We find that heteroatoms could provide additional defect sites for encapsulating iodine while the porous carbon skeleton facilitates redox reactions of iodine and ion intercalation. The combination of ion intercalation with redox reactions of iodine allows for developing rechargeable iodine-carbon batteries free from the unsafe lithium/sodium metals, and hence eliminates the long-standing safety issue. The unique architecture of the hierarchically porous graphitic carbon with heteroatom doping not only provides suitable spaces for both iodine encapsulation and cation intercalation but also generates efficient electronic and ionic transport pathways, thus leading to enhanced performance.Carbon-based electrodes able to intercalate Li + and Na + ions have been exploited for high performing energy storage devices. Here, the authors combine the ion intercalation properties of porous graphitic carbons with the redox chemistry of iodine to produce iodine-carbon batteries with high reversible capacities.

Potassium-Based Dual Ion Battery with Dual-Graphite Electrode.

PubMed

Fan, Ling; Liu, Qian; Chen, Suhua; Lin, Kairui; Xu, Zhi; Lu, Bingan

2017-08-01

A potassium ion battery has potential applications for large scale electric energy storage systems due to the abundance and low cost of potassium resources. Dual graphite batteries, with graphite as both anode and cathode, eliminate the use of transition metal compounds and greatly lower the overall cost. Herein, combining the merits of the potassium ion battery and dual graphite battery, a potassium-based dual ion battery with dual-graphite electrode is developed. It delivers a reversible capacity of 62 mA h g -1 and medium discharge voltage of ≈3.96 V. The intercalation/deintercalation mechanism of K + and PF 6 - into/from graphite is proposed and discussed in detail, with various characterizations to support. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-Temperature Intercalated Graphite Fiber Conductors Fabricated

NASA Technical Reports Server (NTRS)

Gaier, James R.

2002-01-01

Composites of intercalated graphite fibers show promise to significantly reduce the weight of electromagnetic interference shielding in spacecraft and aircraft. Bromine intercalated pitch-based fibers have been among the most heavily studied systems because of their attractive electrical and thermal conductivities and their stability over a wide range of environmental conditions. Previous studies found that the resistivity of bromineintercalated graphite fibers began to increase when the fibers were exposed to temperatures in excess of about 200 C in air for long periods of time. If the temperature was as high as 450 C, the resistivity increased dramatically within a few hours. It remained unclear, however, whether the increase was due to deintercalation of the bromine or to air oxidation of the fibers. Studies were initially directed toward determining the temperature at which bromine would deintercalate from the fibers, and perhaps become a hazard to both personnel and equipment. So the mass of bromine-intercalated graphite fibers was carefully monitored as it was heated in an inert atmosphere, since the fibers are known to oxidize at a lower temperature than they deintercalate. What was found was that the fibers, which are about 18-wt% bromine, did not lose any appreciable mass even at temperatures approaching 1000 C. X-ray diffraction studies showed that there were also no changes in the overall structure of the compound. Resistivity measurements indicated that there is some slight degradation in the electronic structure, in that the resistivity increased by a few percent. Overall, the results show that these materials may be suitable for applications at temperatures at least this high, provided oxygen is excluded. This may enable their use in carbon-ceramic, and perhaps even carbon-carbon composites.

Durability of Intercalated Graphite Epoxy Composites in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Gaier, James R.; Davidson, Michelle L.; Shively, Rhonda

1996-01-01

The electrical conductivity of graphite epoxy composites can be substantially increased by intercalating (inserting guest atoms or molecules between the graphene planes) the graphite fibers before composite formation. The resulting high strength, low density, electrically conducting composites have been proposed for EMI shielding in spacecraft. Questions have been raised, however, about their durability in the space environment, especially with respect to outgassing of the intercalates, which are corrosive species such as bromine. To answer those concerns, six samples of bromine intercalated graphite epoxy composites were included in the third Evaluation of Oxygen Interaction with Materials (EOIM-3) experiment flown on the Space Shuttle Discovery (STS-46). Changes in electrical conductivity, optical reflectance, surface texture, and mass loss for SiO2 protected and unprotected samples were measured after being exposed to the LEO environment for 42 hours. SiO2 protected samples showed no degradation, verifying conventional protection strategies are applicable to bromine intercalated composites. The unprotected samples showed that bromine intercalation does not alter the degradation of graphite-epoxy composites. No bromine was detected to have been released by the fibers allaying fears that outgassing could be disruptive to the sensitive electronics the EMI shield is meant to protect.

Structural and Kinetic Properties of Graphite Intercalation Compounds

DTIC Science & Technology

1982-08-21

the case of FeCI3 , and Dowel2 for Br2, HNO3 and PdC 2 have investigated rates of intercalation to determine diffusion coefficients. Bardhan et al.18...Chim. 21, 1312 (1954). 17. T. Sasa, Y. Takahashi and T. Mukaibo, Carbon 9, 407 (1971). 18. K. K. Bardhan and D. D. L. Chung, Carbon 18, 313 (1980). 19...S. H. Anderson and D. D. L. Chung, Ext. Abst. Program -- Bienn. Conf. Carbon 15, 361 (1981). 20. K. K. Bardhan and D. D. L. Chung, Carbon 18, 303

Method for producing thin graphite flakes with large aspect ratios

DOEpatents

Bunnell, L. Roy

1993-01-01

A method for making graphite flakes of high aspect ratio by the steps of providing a strong concentrated acid and heating the graphite in the presence of the acid for a time and at a temperature effective to intercalate the acid in the graphite; heating the intercalated graphite at a rate and to a temperature effective to exfoliate the graphite in discrete layers; subjecting the graphite layers to ultrasonic energy, mechanical shear forces, or freezing in an amount effective to separate the layes into discrete flakes.

A comparison of the bromination dynamics of various carbon and graphite fibers

NASA Technical Reports Server (NTRS)

Gaier, James R.

1987-01-01

The electrical resistance of four grades of pitch-based graphite fibers and three experimental organic vapor-derived fibers was determined in situ during bromination and subsequent exposure to ambient laboratory air. The results show that the least graphitic pitch-based fiber does not brominate significantly, and that bromination and debrominaton reactions proceed much slower for vapor-derived fibers than for pitch-based ones. It is suggested that this decreased reacton rate is primarily due to the differences in graphene plane orientation between the fiber types. The results also imply that the vapor-derived and pitch-based fibers produce true intercalation compounds.

Manipulating Adsorption-Insertion Mechanisms in Nanostructured Carbon Materials for High-Efficiency Sodium Ion Storage

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

Qiu, Shen; Xiao, Lifen; Sushko, Maria L.

Hard carbon is one of the most promising anode materials for sodium-ion batteries, but the low coulombic efficiency is still a key barrier. In this paper we synthesized a series of nanostructured hard carbon materials with controlled architectures. Using a combination of in-situ XRD mapping, ex-situ NMR, EPR, electrochemical techniques and simulations, an “adsorption-intercalation” (A-I) mechanism is established for Na ion storage. During the initial stages of Na insertion, Na ions adsorb on the defect sites of hard carbon with a wide adsorption energy distribution, producing a sloping voltage profile. In the second stage, Na ions intercalate into graphitic layersmore » with suitable spacing to form NaCx compounds similar to the Li ion intercalation process in graphite, producing a flat low voltage plateau. The cation intercalation with a flat voltage plateau should be enhanced and the sloping region should be avoided. Guided by this knowledge, non-porous hard carbon material has been developed which has achieved high reversible capacity and coulombic efficiency to fulfill practical application.« less

Development of Nanoplatelet Composites

DTIC Science & Technology

2008-12-08

Graphite Intercalation Compounds and Applications, Oxford University Press, 2003. 27 S. Stankovich, D.A. Dikin , D.H.B. Dommett, K.H. Kohlhaas, E.J...Chemistry C 111,7565(2007). 30 S. Stankovich, D.A. Dikin , G.H.B. Dommett, K.M. Kolhaas, E.J. Zimney, E.A. Stach, R.D. Piner, S.T. Ngyuen, and R.A. Ruoff

Graphite fiber intercalation: Basic properties of copper chloride intercalated fibers

NASA Technical Reports Server (NTRS)

Jaworske, D. A.; Miller, J. D.

1986-01-01

In situ resistance measurements were used to follow the intercalation of copper chloride in pitch-based fibers. Subsequent single fiber resistivity measurements reveal a large range of resistivities, from 13 to 160 micro-ohms cm. Additional density measurements reveal a bimodal distribution of mass densities. The dense fibers have lower resistivities and correspond to the stage III compound identified by X-ray diffraction. Neither resistivity nor density correlate with diameter. Both energy dispersive spectroscopy and mass density data suggest that excess chlorine resides in the intercalated fiber, resulting in a stoichiometry of C4.9n CuCl2.5 (where n is the stage number) for the denser fibers. Finally, thermogravimetric analysis shows a 33 percent loss in mass upon heating to 700C. This loss in mass is attributed to loss of both chlorine and carbon.

Multistage Mechanism of Lithium Intercalation into Graphite Anodes in the Presence of the Solid Electrolyte Interface.

PubMed

Dinkelacker, Franz; Marzak, Philipp; Yun, Jeongsik; Liang, Yunchang; Bandarenka, Aliaksandr S

2018-04-25

A so-called solid electrolyte interface (SEI) in a lithium-ion battery largely determines the performance of the whole system. However, it is one of the least understood objects in these types of batteries. SEIs are formed during the initial charge-discharge cycles, prevent the organic electrolytes from further decomposition, and at the same time govern lithium intercalation into the graphite anodes. In this work, we use electrochemical impedance spectroscopy and atomic force microscopy to investigate the properties of a SEI film and an electrified "graphite/SEI/electrolyte interface". We reveal a multistage mechanism of lithium intercalation and de-intercalation in the case of graphite anodes covered by SEI. On the basis of this mechanism, we propose a relatively simple model, which perfectly explains the impedance response of the "graphite/SEI/electrolyte" interface at different temperatures and states of charge. From the whole data obtained in this work, it is suggested that not only Li + but also negatively charged species, such as anions from the electrolyte or functional groups of the SEI, likely interact with the surface of the graphite anode.

Graphite intercalation compound with iodine as the major intercalant

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh; Kucera, Donald

1992-01-01

Halogenated CBr(sub x)I(sub y) (1 less than y/x less than 10) was made by exposing graphite materials with interplanar spacing in the 3.35 to 3.41 A range to either pure Br2 or an I2-Br2 mixture, and then to iodine vapor containing a small amount of Br2. The electrical resistivity of this product is from 3 to 6.5 times the pristine value. The presence of a small amount of isoprene rubber in the reaction significantly increased the iodine to bromine ratio in the product. In this reaction, rubber is known to generate HBr and to slowly remove bromine from the vapor. The halogenation generally caused a 22 to 25 percent weight increase. The halogens were found uniformly distributed in the product interior. However, although the surface contains very little iodine, it has high concentrations of bromine and oxygen. It is believed that the high concentrations of bromine and oxygen in this surface cause the halogenated fiber to be more resistant to fluorine attack during subsequent fluorination to fabricate graphite fluoride fibers.

Hindered Glymes for Graphite-Compatible Electrolytes.

PubMed

Shanmukaraj, Devaraj; Grugeon, Sylvie; Laruelle, Stephane; Armand, Michel

2015-08-24

Organic carbonate mixtures are used almost exclusively as lithium battery electrolyte solvents. The linear compounds (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate) act mainly as thinner for the more viscous and high-melting ethylene carbonate but are the least stable component and have low flash points; these are serious handicaps for lifetime and safety. Polyethers (glymes) are useful co-solvents, but all formerly known representatives solvate Li(+) strongly enough to co-intercalate in the graphite negative electrode and exfoliate it. We have put forward a new electrolyte composition comprising a polyether to which a bulky tert-butyl group is attached ("hindered glyme"), thus completely preventing co-intercalation while maintaining good conductivity. This alkyl-carbonate-free electrolyte shows remarkable cycle efficiency of the graphite electrode, not only at room temperature, but also at 50 and 70 °C in the presence of lithium bis(fluorosulfonimide). The two-ethylene-bridge hindered glyme has a high boiling point and a flash point of 80 °C, a considerable advantage for safety. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Danial, Wan Hazman, E-mail: hazmandanial@gmail.com; Majid, Zaiton Abdul, E-mail: zaiton@kimia.fs.utm.my; Aziz, Madzlan

The present work reports the synthesis and characterization of graphene via electrochemical exfoliation of graphite rod using two-electrode system assisted by Sodium Dodecyl Sulphate (SDS) as a surfactant. The electrochemical process was carried out with sequence of intercalation of SDS onto the graphite anode followed by exfoliation of the SDS-intercalated graphite electrode when the anode was treated as cathode. The effect of intercalation potential from 5 V to 9 V and concentration of the SDS surfactant of 0.1 M and 0.01 M were investigated. UV-vis Spectroscopic analysis indicated an increase in the graphene production with higher intercalation potential. Transmission Electron Microscopy (TEM)more » analysis showed a well-ordered hexagonal lattice of graphene image and indicated an angle of 60° between two zigzag directions within the honeycomb crystal lattice. Raman spectroscopy analysis shows the graphitic information effects after the exfoliation process.« less

Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite

NASA Technical Reports Server (NTRS)

West, William C.; Whitacre, Jay F.; Leifer, Nicole; Greenbaum, Steve; Smart, Marshall; Bugga, Ratnakumar; Blanco, Mario; Narayanan, S. R.

2007-01-01

We have demonstrated a route to reversibly intercalate fluoride-anion receptor complexes in graphite via a nonaqueous electrochemical process. This approach may find application for a rechargeable lithium-fluoride dual-ion intercalating battery with high specific energy. The cell chemistry presented here uses graphite cathodes with LiF dissolved in a nonaqueous solvent through the aid of anion receptors. Cells have been demonstrated with reversible cathode specific capacity of approximately 80 mAh/g at discharge plateaus of upward of 4.8 V, with graphite staging of the intercalant observed via in situ synchrotron X-ray diffraction during charging. Electrochemical impedance spectroscopy and B-11 nuclear magnetic resonance studies suggest that cointercalation of the anion receptor with the fluoride occurs during charging, which likely limits the cathode specific capacity. The anion receptor type dictates the extent of graphite fluorination, and must be further optimized to realize high theoretical fluorination levels. To find these optimal anion receptors, we have designed an ab initio calculations-based scheme aimed at identifying receptors with favorable fluoride binding and release properties.

Purification and preparation of graphite oxide from natural graphite

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

Panatarani, C., E-mail: c.panatarani@phys.unpad.ac.id; Muthahhari, N.; Joni, I. Made

2016-03-11

Graphite oxide has attracted much interest as a possible route for preparation of natural graphite in the large-scale production and manipulation of graphene as a material with extraordinary electronic properties. Graphite oxide was prepared by modified Hummers method from purified natural graphite sample from West Kalimantan. We demonstrated that natural graphite is well-purified by acid leaching method. The purified graphite was proceed for intercalating process by modifying Hummers method. The modification is on the reaction time and temperature of the intercalation process. The materials used in the intercalating process are H{sub 2}SO{sub 4} and KMNO{sub 4}. The purified natural graphitemore » is analyzed by carbon content based on Loss on Ignition test. The thermo gravimetricanalysis and the Fouriertransform infrared spectroscopy are performed to investigate the oxidation results of the obtained GO which is indicated by the existence of functional groups. In addition, the X-ray diffraction and energy dispersive X-ray spectroscopy are also applied to characterize respectively for the crystal structure and elemental analysis. The results confirmed that natural graphite samples with 68% carbon content was purified into 97.68 % carbon content. While the intercalation process formed a formation of functional groups in the obtained GO. The results show that the temperature and reaction times have improved the efficiency of the oxidation process. It is concluded that these method could be considered as an important route for large-scale production of graphene.« less

Two-Step Electrochemical Intercalation and Oxidation of Graphite for the Mass Production of Graphene Oxide.

PubMed

Cao, Jianyun; He, Pei; Mohammed, Mahdi A; Zhao, Xin; Young, Robert J; Derby, Brian; Kinloch, Ian A; Dryfe, Robert A W

2017-12-06

Conventional chemical oxidation routes for the production of graphene oxide (GO), such as the Hummers' method, suffer from environmental and safety issues due to their use of hazardous and explosive chemicals. These issues are addressed by electrochemical oxidation methods, but such approaches typically have a low yield due to inhomogeneous oxidation. Herein we report a two-step electrochemical intercalation and oxidation approach to produce GO on the large laboratory scale (tens of grams) comprising (1) forming a stage 1 graphite intercalation compound (GIC) in concentrated sulfuric acid and (2) oxidizing and exfoliating the stage 1 GIC in an aqueous solution of 0.1 M ammonium sulfate. This two-step approach leads to GO with a high yield (>70 wt %), good quality (>90%, monolayer), and reasonable oxygen content (17.7 at. %). Moreover, the as-produced GO can be subsequently deeply reduced (3.2 at. % oxygen; C/O ratio 30.2) to yield highly conductive (54 600 S m -1 ) reduced GO. Electrochemical capacitors based on the reduced GO showed an ultrahigh rate capability of up to 10 V s -1 due to this high conductivity.

Semiconductor cooling apparatus

NASA Technical Reports Server (NTRS)

Banks, Bruce A. (Inventor); Gaier, James R. (Inventor)

1993-01-01

Gas derived graphite fibers generated by the decomposition of an organic gas are joined with a suitable binder. This produces a high thermal conductivity composite material which passively conducts heat from a source, such as a semiconductor, to a heat sink. The fibers may be intercalated. The intercalate can be halogen or halide salt, alkaline metal, or any other species which contributes to the electrical conductivity improvement of the graphite fiber. The fibers are bundled and joined with a suitable binder to form a high thermal conductivity composite material device. The heat transfer device may also be made of intercalated highly oriented pyrolytic graphite and machined, rather than made of fibers.

Radiation Protection of New Lightweight Electromagnetic Interference Shielding Materials Determined

NASA Technical Reports Server (NTRS)

1996-01-01

Weight savings as high as 80 percent could be achieved by simply switching from aluminum electromagnetic interference (EMI) shielding covers for spacecraft power systems to EMI covers made from intercalated graphite fiber composites. Because EMI covers typically make up about one-fifth of the power system mass, this change would decrease the mass of a spacecraft power system by more than 15 percent. Intercalated graphite fibers are made by diffusing guest atoms or molecules, such as bromine, between the carbon planes of the graphite fibers. The resulting bromine-intercalated fibers have mechanical and thermal properties nearly identical to pristine graphite fibers, but their resistivity is lower by a factor of 5, giving them better electrical conductivity than stainless steel and making these composites suitable for EMI shielding.

Electrical and galvanomagnetic properties of nanoporous carbon samples impregnated with bromine

NASA Astrophysics Data System (ADS)

Danishevskii, A. M.; Popov, V. V.; Kyutt, R. N.; Gordeev, S. K.

2013-07-01

Nanoporous carbon samples with a large specific surface area can be filled with heavier elements or their compounds, which makes it possible to investigate the interaction of their electronic subsystems with carbon. One of the elements convenient for filling pores of carbon materials is bromine. Impregnation of nanoporous carbon samples with bromine causes the occurrence of the processes of micropore filling, monolayer adsorption, and intercalation. It has been found that samples impregnated with bromine substantially change their electrical and galvanomagnetic properties, and these changes depend on the structure of the samples. It has been shown that, if in the skeleton of a porous carbon sample there is a fraction of graphite clusters, the impregnation of the sample with bromine increases the concentration of charged carriers (holes). But when the sample has a quasi-amorphous structure, the injection of bromine into the sample leads to the appearance of a certain concentration of electrons in addition to charged mobile holes of the initial sample; i.e., the electrical conductivity becomes bipolar. In the former case, bromine molecules intercalate graphite clusters and, since bromine is an acceptor during intercalation of graphite, the hole concentration in the carbon skeleton network increases. In the latter case, bromine molecules can only be adsorbed on pore walls. As a result, the adsorption interaction between the electron shells of bromine molecules and the carbon surface leads to the formation of a donor layer near the surface and to the generation of electrons in the carbon skeleton network.

Charge and discharge characteristics of lithium-ion graphite electrodes in solid-state cells

NASA Astrophysics Data System (ADS)

Lemont, S.; Billaud, D.

Lithium ions have been electrochemically intercalated into graphite in solid-state cells operating with solid polymer electrolytes based on poly(ethylene oxide) (PEO) complexed with lithium perchlorate (LiClO 4). The working composite electrode is composed of active-divided natural graphite associated with P(EO) 8-LiClO 4 acting as a binder and a Li + ionic conductor. Intercalation and de-intercalation of Li + were performed using galvanostatic or voltammetry techniques. The curves obtained in our solid-state cells were compared with those performed in liquid ethylene carbonate-LiClO 4 electrolyte. It is shown that in solid-state cells, side reactions occur both in the reduction and in the oxidation processes which leads to some uncertainty in the determination of the maximum reversible capacity of the graphite material.

Biopolymer-modified graphite oxide nanocomposite films based on benzalkonium chloride-heparin intercalated in graphite oxide

NASA Astrophysics Data System (ADS)

Meng, Na; Zhang, Shuang-Quan; Zhou, Ning-Lin; Shen, Jian

2010-05-01

Heparin is a potent anticoagulant agent that interacts strongly with antithrombin III to prevent the formation of fibrin clots. In the present work, poly(dimethylsiloxane)(PDMS)/graphite oxide-benzalkonium chloride-heparin (PDMS/modified graphite oxide) nanocomposite films were obtained by the solution intercalation technique as a possible drug delivery system. The heparin-benzalkonium chloride (BAC-HEP) was intercalated into graphite oxide (GO) layers to form GO-BAC-HEP (modified graphite oxide). Nanocomposite films were characterized by XRD, SEM, TEM, ATR-FTIR and TGA. The modified graphite oxide was observed to be homogeneously dispersed throughout the PDMS matrix. The effect of modified graphite oxide on the mechanical properties of the nanocomposite film was investigated. When the modified graphite oxide content was lower than 0.2 wt%, the nanocomposites showed excellent mechanical properties. Furthermore, nanocomposite films become delivery systems that release heparin slowly to make the nanocomposite films blood compatible. The in vitro studies included hemocompatibility testing for effects on platelet adhesion, platelet activation, plasma recalcification profiles, and hemolysis. Results from these studies showed that the anticoagulation properties of PDMS/GO-BCA-HEP nanocomposite films were greatly superior to those for no treated PDMS. Cell culture assay indicated that PDMS/GO-BCA-HEP nanocomposite films showed enhanced cell adhesion.

Intercalation of Li Ions into a Graphite Anode Material: Molecular Dynamics Simulations

NASA Astrophysics Data System (ADS)

Abou Hamad, Ibrahim; Novotny, Mark

2008-03-01

Large-scale molecular dynamics simulations of the anode half-cell of a lithium-ion battery are presented. The model system is composed of an anode represented by a stack of graphite sheets, an electrolyte of ethylene carbonate and propylene carbonate molecules, and lithium and hexafluorophosphate ions. The simulations are done in the NVT ensemble and at room temperature. One charging scheme explored is normal charging in which intercalation is enhanced by electric charges on the graphitic sheets. The second charging mechanism has an external applied oscillatory electric field of amplitude A and frequency f. The simulations were performed on 2.6 GHz Opteron processors, using 160 processors at a time. Our simulation results show an improvement in the intercalation time of the lithium ions for the second charging mechanism. The dependence of the intercalation time on A and f will be discussed.

Advanced rechargeable aluminium ion battery with a high-quality natural graphite cathode

PubMed Central

Wang, Di-Yan; Wei, Chuan-Yu; Lin, Meng-Chang; Pan, Chun-Jern; Chou, Hung-Lung; Chen, Hsin-An; Gong, Ming; Wu, Yingpeng; Yuan, Chunze; Angell, Michael; Hsieh, Yu-Ju; Chen, Yu-Hsun; Wen, Cheng-Yen; Chen, Chun-Wei; Hwang, Bing-Joe; Chen, Chia-Chun; Dai, Hongjie

2017-01-01

Recently, interest in aluminium ion batteries with aluminium anodes, graphite cathodes and ionic liquid electrolytes has increased; however, much remains to be done to increase the cathode capacity and to understand details of the anion–graphite intercalation mechanism. Here, an aluminium ion battery cell made using pristine natural graphite flakes achieves a specific capacity of ∼110 mAh g−1 with Coulombic efficiency ∼98%, at a current density of 99 mA g−1 (0.9 C) with clear discharge voltage plateaus (2.25–2.0 V and 1.9–1.5 V). The cell has a capacity of 60 mAh g−1 at 6 C, over 6,000 cycles with Coulombic efficiency ∼ 99%. Raman spectroscopy shows two different intercalation processes involving chloroaluminate anions at the two discharging plateaus, while C–Cl bonding on the surface, or edges of natural graphite, is found using X-ray absorption spectroscopy. Finally, theoretical calculations are employed to investigate the intercalation behaviour of choloraluminate anions in the graphite electrode. PMID:28194027

Advanced rechargeable aluminium ion battery with a high-quality natural graphite cathode

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

Wang, Di-Yan; Wei, Chuan-Yu; Lin, Meng-Chang

There has been some interest in aluminium ion batteries with aluminium anodes, graphite cathodes and ionic liquid electrolytes has increased; however, much remains to be done to increase the cathode capacity and to understand details of the anion–graphite intercalation mechanism. An aluminium ion battery cell made using pristine natural graphite flakes achieves a specific capacity of B110 mAhg -1 with Coulombic efficiency B98%, at a current density of 99mAg -1 (0.9 C) with clear discharge voltage plateaus (2.25–2.0 V and 1.9–1.5 V). The cell has a capacity of 60mAhg -1 at 6 C, over 6,000 cycles with Coulombic efficiency Bmore » 99%. Raman spectroscopy shows two different intercalation processes involving chloroaluminate anions at the two discharging plateaus, while C–Cl bonding on the surface, or edges of natural graphite, is found using X-ray absorption spectroscopy. Lastly, theoretical calculations are employed to investigate the intercalation behaviour of choloraluminate anions in the graphite electrode.« less

Advanced rechargeable aluminium ion battery with a high-quality natural graphite cathode

DOE PAGES

Wang, Di-Yan; Wei, Chuan-Yu; Lin, Meng-Chang; ...

2017-02-13

There has been some interest in aluminium ion batteries with aluminium anodes, graphite cathodes and ionic liquid electrolytes has increased; however, much remains to be done to increase the cathode capacity and to understand details of the anion–graphite intercalation mechanism. An aluminium ion battery cell made using pristine natural graphite flakes achieves a specific capacity of B110 mAhg -1 with Coulombic efficiency B98%, at a current density of 99mAg -1 (0.9 C) with clear discharge voltage plateaus (2.25–2.0 V and 1.9–1.5 V). The cell has a capacity of 60mAhg -1 at 6 C, over 6,000 cycles with Coulombic efficiency Bmore » 99%. Raman spectroscopy shows two different intercalation processes involving chloroaluminate anions at the two discharging plateaus, while C–Cl bonding on the surface, or edges of natural graphite, is found using X-ray absorption spectroscopy. Lastly, theoretical calculations are employed to investigate the intercalation behaviour of choloraluminate anions in the graphite electrode.« less

Functional interface of polymer modified graphite anode

NASA Astrophysics Data System (ADS)

Komaba, S.; Ozeki, T.; Okushi, K.

Graphite electrodes were modified by polyacrylic acid (PAA), polymethacrylic acid (PMA), and polyvinyl alcohol (PVA). Their electrochemical properties were examined in 1 mol dm -3 LiClO 4 ethylene carbonate:dimethyl carbonate (EC:DMC) and propylene carbonate (PC) solutions as an anode of lithium ion batteries. Generally, lithium ions hardly intercalate into graphite in the PC electrolyte due to a decomposition of the PC electrolyte at ca. 0.8 V vs. Li/Li +, and it results in the exfoliation of the graphene layers. However, the modified graphite electrodes with PAA, PMA, and PVA demonstrated the stable charge-discharge performance due to the reversible lithium intercalation not only in the EC:DMC but also in the PC electrolytes since the electrolyte decomposition and co-intercalation of solvent were successfully suppressed by the polymer modification. It is thought that these improvements were attributed to the interfacial function of the polymer layer on the graphite which interacted with the solvated lithium ions at the electrode interface.

Dielectric relaxation of alkyl chains in graphite oxide and n-alkylammonium halides

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

Ai, Xiaoqian; Tian, Yuchen; Gu, Min, E-mail: mgu@nju.edu.cn

2016-05-15

The dynamic of n-alkylammonium halides and n-alkylammonium cations (n = 12, 14, 16, 18) intercalated in graphite oxide (GO) have been investigated with complex impedance spectroscopy. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, elemental analysis and thermogravimetry served to characterize the materials. The intercalated alkylammonium cations distributes as monolayers (when n = 12, 14 or 16) or bilayers (when n = 18), with their long axis parallel to GO layers, and with cations of headgroups bonded ionically to C-O{sup -} groups of GO; backbones of the confined molecules remain free. All halides and intercalation compounds suffer dielectric loss atmore » low temperature. Arrhenius plots of the thermal dependence of the loss peaks, which are asymmetric, produce apparent activation energies that rise with increasing n. Ngai’s correlated-state model helps to correct for effects of dipole-dipole interaction, leading to virtually identical values for actual activation energy of 110 meV ± 5%; the values are also almost the same as the barrier energy for internal rotation in the alkyl macromolecule. We conclude that the relaxation of the alkylammonium cations arises not from C{sub 3} reorientation of the CH{sub 3} at its headgroup, but from small-angle wobbling around its major axis, an intrinsic motion.« less

Intercalated graphite fiber composites as EMI shields in aerospace structures

NASA Technical Reports Server (NTRS)

Gaier, James R.

1990-01-01

The requirements for electromagnetic interference (EMI) shielding in aerospace structures are complicated over that of ground structures by their weight limitations. As a result, the best EMI shielding materials must blend low density, high strength, and high elastic modulus with high shielding ability. In addition, fabrication considerations including penetrations and joints play a major role. The EMI shielding properties are calculated for shields formed from pristine and intercalated graphite fiber/epoxy composites and compared to preliminary experimental results and to shields made from aluminum. Calculations indicate that EMI shields could be fabricated from intercalated graphite composites which would have less than 12 percent of the mass of conventional aluminum shields, based on mechanical properties and shielding properties alone.

Graphite intercalation with fluoroanions by chemical and electrochemical methods

NASA Astrophysics Data System (ADS)

Ozmen-Monkul, Bahar

New acceptor-type graphite intercalation compounds (GICs) containing perfluoroalkyl anions have been synthesized by using both chemical and electrochemical methods and characterized by elemental and thermogravimetric analyses. Investigation into these graphite intercalation compounds can provide novel materials and a detailed understanding of their properties. GICs of composition Cx[FB(C2F 5)3]·deltaF are prepared for the first time by the intercalation of fluoro-tris(pentafluoroethyl)borate anion, [FB(C2F 5)3]-, under ambient conditions in aqueous (48%) hydrofluoric acid containing the oxidant K2[MnF6]. Powder-XRD data indicate that products are pure stage 2 and physical mixture of stage 2 and stage 3 after 1 h to 20 h reaction times. The calculated basal repeat distance, Ic, is 1.20 nm for stage 2 and 1.54-1.56 nm for stage 3 GICs, corresponding to gallery heights of di = 0.86-0.89 nm. In addition, stage 2 GIC of C x[FB(C2F5)3]·deltaCH 3NO2 having di = 0.84 nm is prepared by electrochemical oxidation of graphite in a nitromethane electrolyte. The elemental analyses of these complex GICs required that a new sample digestion protocol be developed. After digestion, the fluoride amounts in these GIC samples were analyzed by using ion-selective fluoride combination electrode. The method developed is able to provide fluoride anion content in GICs without interference from the decomposition products of [FB(C 2F5)3]- anion. For the boron analyses the same digestion procedure above is used and the B contents were determined by ICP-AES. For Cx[FB(C2F 5)3]·deltaF, both compositional parameters x and delta are obtained from the results of elemental B and F analyses. For the chemically prepared GICs at 1 h to 20 h, calculated x values were in the range of 51-56 and the calculated delta values increased with reaction time from approx. 0-2. Combining B analysis and TGA mass loss gives a composition of x = 44 and delta = 0.37 for the electrochemically prepared GIC of Cx[FB(C2F5)3]·deltaCH 3NO2. Energy minimized structure for the isolated borate anion and powder XRD data show that the borate anions adopt a "lying-down" orientation where the long axes of [FB(C2F5)3] - intercalate anions are parallel to the encasing graphene sheets. The same electrochemical synthesis strategy is also used for the preparation of a new acceptor-type GIC containing the cyclo-hexafluoropropane-1,3-bis(sulfonyl)amide anion, [CF2(CF2SO2)2N] -. The gallery heights of 0.85-0.86 nm are determined by powder X-ray diffraction for stage 2 and 3 products. These GICs are obtained by electrochemical oxidation of graphite in a nitromethane electrolyte. GICs containing the linear anion, [(CF3SO2)2N]- are also prepared in order to compare the gallery heights and the electron charge distributions that helps to understand the GIC stabilities within the graphene sheets. The compositions of GICs containing [CF2(CF 2SO2)2N]- are determined by thermogravimetric, fluorine and nitrogen elemental analyses. GICs of composition Cx[(C2F 5)3PF3] are prepared for the first time by the intercalation of tris(pentafluoroethyl)trifluorophosphate (FAP) anion, [(C 2F5)3PF3]- by electrochemical oxidation of graphite. Powder-XRD data indicate that products are of stages 2-4 with gallery heights of 0.82-0.86 nm. These GICs are characterized by the same methods using TGA and F ion-selective probe analyses.

Critical role of intercalated water for electrocatalytically active nitrogen-doped graphitic systems

DOE PAGES

Martinez, Ulises; Dumont, Joseph H.; Holby, Edward F.; ...

2016-03-18

Graphitic materials are very essential in energy conversion and storage because of their excellent chemical and electrical properties. The strategy for obtaining functional graphitic materials involves graphite oxidation and subsequent dissolution in aqueous media, forming graphene-oxide nanosheets (GNs). Restacked GNs contain substantial intercalated water that can react with heteroatom dopants or the graphene lattice during reduction. We demonstrate that removal of intercalated water using simple solvent treatments causes significant structural reorganization, substantially affecting the oxygen reduction reaction (ORR) activity and stability of nitrogen-doped graphitic systems. Amid contrasting reports describing the ORR activity of GN-based catalysts in alkaline electrolytes, we demonstratemore » superior activity in an acidic electrolyte with an onset potential of ~0.9 V, a half-wave potential (E ½) of 0.71 V, and a selectivity for four-electron reduction of >95%. Finally and further, durability testing showed E ½ retention >95% in N 2- and O 2-saturated solutions after 2000 cycles, demonstrating the highest ORR activity and stability reported to date for GN-based electrocatalysts in acidic media.« less

Influence of solvent species on the charge-discharge characteristics of a natural graphite electrode

NASA Astrophysics Data System (ADS)

Fujimoto, Masahisa; Shoji, Yoshihiro; Kida, Yoshinori; Ohshita, Ryuji; Nohma, Toshiyuki; Nishio, Koji

The charge-discharge characteristics of a natural graphite electrode are examined in a mixed solvent composed of ethylene carbonate (EC) and propylene carbonate (PC). The characteristics are influenced largely by the solvent species. Natural graphite electrode displays good charge-discharge characteristics in an electrolyte containing EC with a high volume fraction. In an electrolyte containing PC, however, the electrode cannot be charged and the solvent is decomposed. X-ray photoelectron spectroscopy is used to obtain information about the surface of natural graphite. A thin LiF layer, the decomposition product of lithium hexafluorophosphate (LiPF 6), is formed on the surface of the natural graphite charged to 0.5 V (vs. Li/Li +) in an electrolyte containing a high volume fraction of EC. On the other hand, LiF and a carbonate compound are formed in the bulk and on the surface of natural graphite when the volume fraction of PC is high. These results suggest that the thin LiF layer, which is produced at a potential higher than 0.5 V (vs. Li/Li +) on the surface of natural graphite, enables the lithium ions to intercalate into the natural graphite without further decomposition of the electrolyte.

Method for fabricating carbon/lithium-ion electrode for rechargeable lithium cell

NASA Technical Reports Server (NTRS)

Attia, Alan I. (Inventor); Halpert, Gerald (Inventor); Huang, Chen-Kuo (Inventor); Surampudi, Subbarao (Inventor)

1995-01-01

The method includes steps for forming a carbon electrode composed of graphitic carbon particles adhered by an ethylene propylene diene monomer binder. An effective binder composition is disclosed for achieving a carbon electrode capable of subsequent intercalation by lithium ions. The method also includes steps for reacting the carbon electrode with lithium ions to incorporate lithium ions into graphitic carbon particles of the electrode. An electrical current is repeatedly applied to the carbon electrode to initially cause a surface reaction between the lithium ions and to the carbon and subsequently cause intercalation of the lithium ions into crystalline layers of the graphitic carbon particles. With repeated application of the electrical current, intercalation is achieved to near a theoretical maximum. Two differing multi-stage intercalation processes are disclosed. In the first, a fixed current is reapplied. In the second, a high current is initially applied, followed by a single subsequent lower current stage. Resulting carbon/lithium-ion electrodes are well suited for use as an anode in a reversible, ambient temperature, lithium cell.

Technological hurdles to the application of intercalated graphite fibers

NASA Technical Reports Server (NTRS)

Gaier, James R.

1988-01-01

Before intercalated graphite fibers can be developed as an effective power material, there are several technological hurdles which must be overcome. These include the environmental stability, homogeneity and bulk properties, connection procedures, and costs. Strides were made within the last several years in stability and homogeneity of intercalated graphite fibers. Bulk properties and connection procedures are areas of active research now. Costs are still prohibitive for all but the most demanding applications. None of these problems, however, appear to be unsolvable, and their solution may result in wide spread GOC application. The development of a relatively simple technology application, such as EMI shielding, would stimulate the solution of scale-up problems. Once this technology is developed, then more demanding applications, such as power bus bars, may be possible.

Environmental stability of intercalated graphite fibers

NASA Technical Reports Server (NTRS)

Gaier, J. R.; Jaworske, D. A.

1985-01-01

Graphite fibers intercalated with bromine, iodine monochloride, ferric chloride, and cupric chloride were subjected to stability tests under four environments which are encountered by engineering materials in the aerospace industry: ambient laboratory conditions, as would be experienced during handling operations and terrestrial applications; high vacuum, as would be experienced in space applications; high humidity, as would be experienced in marine applications; and high temperature, as would be experienced in some processing steps and applications. Monitoring the resistance of the fibers at ambient laboratory conditions revealed that only the ferric chloride intercalated fibers were unstable, due to absorption of water from the air. All four types of intercalated fibers were unstable, due to absorption of water from the air. All four types of intercalated fibers were stable for long periods under high vacuum. Ferric chloride, cupric chloride, and iodine monochloride intercalated fibers were sensitive to high humidity conditions. All intercalated fibers began to degrade above 250 C. The order of their thermal stability, from lowest to highest, was cupric chloride, iodine monochloride, bromine, and ferric chloride. Of the four types of intercalated fibers tested, the bromine intercalated fibers appear to have the most potential for application, based on environmental stability.

Staging properties of potassium-ammonia ternary graphite intercalation compounds at high ammonia pressure

NASA Astrophysics Data System (ADS)

Qian, X. W.; Solin, S. A.

1989-04-01

The pressure dependence of the (00l) x-ray diffraction patterns of the ternary graphite intercalation compound K(NH3)xC24 has been studied in the range 0.5-11 kbar (for which x~4.5) using a diamond anvil cell. A special apparatus for loading the cell with liquid ammonia at room temperature has been constructed and is briefly described. In these experiments, the pressure-transmitting fluid was also an intercalant, namely ammonia. Therefore, the chemical potential of this species was linearly coupled to the applied pressure in contrast to the usual case where the pressure-transmitting fluid is chemically passive. The pressure dependences of the basal spacings and of the relative intensities of key reflections have been measured, as have the compressibilities of the stage-1 and stage-2 components of the two-phase system. Basal-spacing anomalies and anomalies in the relative intensities occur at pressures of ~3.5 and 8.0 kbar and are tentatively attributed to in-plane coordination changes in the potassium-ammonia ratio. Using thermodynamic arguments and Le Chatelier's principle we show quantitatively that a staging phase transition from pure stage-1 phase to an admixture of stage-1 and stage-2 is expected with increased pressure above 10 bar in agreement with experiment. The saturation ammonia compositions (x values) of the admixed stages are found to be 4.5 and 5.4 for the stage-1 and -2 components, respectively. This result is interpreted as evidence that the composition is not sterically limited but is determined by the binding energy of ammonia for potassium and by the perturbation to this energy from the guest-host interaction.

Intercalation of Lithium in Pitch-Based Graphitized Carbon Fibers Chemically Modified by Fluorine: Soft Carbon With or Without an Oxide Surface

NASA Technical Reports Server (NTRS)

Hung, Ching-Chen; Prisko, Aniko

1999-01-01

The effects of carbon structure and surface oxygen on the carbon's performance as the anode in lithium-ion battery were studied. Two carbon materials were used for the electrochemical tests: soft carbon made from defluorination of graphite fluoride, and the carbon precursor from which the graphite fluoride was made. In this research the precursor was graphitized carbon fiber P-100. It was first fluorinated to form CF(0.68), then defluorinated slowly at 350 to 450 C in bromoform, and finally heated in 1000 C nitrogen before exposed to room temperature air, producing disordered soft carbon having basic surface oxides. This process caused very little carbon loss. The electrochemical test involved cycles of lithium intercalation and deintercalation using C/saturated LiI-50/50 (vol %) EC and DMC/Li half cell. The cycling test had four major results. (1) The presence of a basic oxide surface may prevent solvent from entering the carbon structure and therefore prolong the carbon's cycle life for lithium intercalation-deintercalation. (2) The disordered soft carbon can store lithium through two different mechanisms. One of them is lithium intercalation. which gives the disordered carbon an electrochemical behavior similar to its more ordered graphitic precursor. The other is unknown in its chemistry, but is responsible for the high-N,oltage portion (less than 0.3V) of the charge-discharge curve. (3) Under certain conditions, the disordered carbon can store more lithium than its precursor. (4) These sample and its precursor can intercalate at 200 mA/g. and deintercalate at a rate of 2000 mA/g without significant capacity loss.

Experimental and Theoretical Studies of Donor-Type Graphite Intercalated Compounds.

DTIC Science & Technology

1980-12-20

UNLIMITED. j = +2 IS 230 THE VIEW, OPINIONS, AND/OR FINDINGS CONTAINED IN THIS REPORT ARE THOSE OF THE AUTHOR(S) AND SHOULD NOT BE CONSTRUED AS AN...entered In Block 20. It different lvoo, Report) N A IS. SUPPLEMENTARY NOTES The view, opinions, and/or findings contained in this report are those of...conductivity. This interpretation remains somewhat controversial, in the sense that the Japanese group under Prof. Tanuma do not find a positive Hall

Observation of Landau levels in potassium-intercalated graphite under a zero magnetic field

PubMed Central

Guo, Donghui; Kondo, Takahiro; Machida, Takahiro; Iwatake, Keigo; Okada, Susumu; Nakamura, Junji

2012-01-01

The charge carriers in graphene are massless Dirac fermions and exhibit a relativistic Landau-level quantization in a magnetic field. Recently, it has been reported that, without any external magnetic field, quantized energy levels have been also observed from strained graphene nanobubbles on a platinum surface, which were attributed to the Landau levels of massless Dirac fermions in graphene formed by a strain-induced pseudomagnetic field. Here we show the generation of the Landau levels of massless Dirac fermions on a partially potassium-intercalated graphite surface without applying external magnetic field. Landau levels of massless Dirac fermions indicate the graphene character in partially potassium-intercalated graphite. The generation of the Landau levels is ascribed to a vector potential induced by the perturbation of nearest-neighbour hopping, which may originate from a strain or a gradient of on-site potentials at the perimeters of potassium-free domains. PMID:22990864

Recent Studies on Metal Oxides as Anodes for Li-ION Batteries

NASA Astrophysics Data System (ADS)

Sharma, N.; Subba Rao, G. V.; Chowdari, B. V. R.

Commercial lithium ion batteries (LIB) use layer-type compounds as the electrode materials and Li-ion conducting liquid or polymeric gel as the electrolyte. The preferred cathode and anode are LiCoO2 and graphite respectively. Efforts to improve the performance as well as safety-in-operation of LIB led to the search for alternate electrode materials. As regards the anodes, metal-oxide systems received special attention: Tin (Sn) containing mixed oxides and various 3d- and 4d- transition metal (M) mixed oxides. The reversible capacities in these systems arise either from alloying/de-alloying, formation/decomposition of Li2O aided by the nanosize metal (M) particles/Li-M-O bronze or Li-intercalation/de-intercalation. A brief account of the recent studies is presented.

Graphene-based materials via benzidine-assisted exfoliation and reduction of graphite oxide and their electrochemical properties

NASA Astrophysics Data System (ADS)

Vermisoglou, E. C.; Giannakopoulou, T.; Romanos, G.; Boukos, N.; Psycharis, V.; Lei, C.; Lekakou, C.; Petridis, D.; Trapalis, C.

2017-01-01

Benzidine, a compound bearing aromatic rings and terminal amino groups, was employed for the intercalation and simultaneous reduction of graphite oxide (GO). The aromatic diamine can be intercalated into GO as follows: (1) by grafting with the epoxy groups of GO, (2) by hydrogen bonding with the oxygen containing groups of GO. Stacking between benzidine aromatic rings and unoxidized domains of GO may occur through π-π interaction. The role of benzidine is influenced by pH conditions and the weight ratio GO/benzidine. Two weight ratios were tested i.e. 1:2 and 1:3. Under strong alkaline conditions through K2CO3 addition (pH ∼10.4-10.6) both intercalation and reduction of GO via amino groups occur, while under strong acidic conditions through HCl addition (pH ∼1.4-2.2) π-π stacking is preferred. When no base or acid is added (pH ∼5.2) and the weight ratio is 1:2, there are indications that reduction and π-π stacking occur, while at a GO/benzidine weight ratio 1:3 intercalation via amino groups and reduction seem to dominate. The aforementioned remarks render benzidine a multifunctional tool towards production of reduced graphene oxide. The effect of pH conditions and the GO/benzidine weight ratio on the quality and the electrochemical properties of the produced graphene-based materials were investigated. Cyclic voltammetry measurements using three-electrode cell and KCl aqueous solution as an electrolyte gave specific capacitance values up to ∼178 F/g. When electric double-layer capacitors (EDLC) were fabricated from these materials, the maximum capacitance in organic electrolyte i.e., tetraethyl ammonium tetrafluoroborate (TEABF4) in polycarbonate (PC) was ∼29 F/g.

Rheological and electrical properties of hybrid nanocomposites of epoxy resins filled with graphite nanoplatelets and carbon black.

PubMed

Truong, Quang-Trung; Lee, Seon-Suk; Lee, Dai-Soo

2011-02-01

Graphite nanoplatelets (GNP) were prepared by microwave irradiation of natural graphites intercalated with ferric chloride in nitromethane (GIC). Intercalated structure of GIC was confirmed by X-ray diffraction patterns. SEM images of GIC after microwave irradiation showed the exfoliation of GIC, the formation of GNPs. Hybrid nanocomposites of bisphenol-A type epoxy resins filled with GNP and a conductive carbon black (CB) were prepared and rheological and electrical properties of the nanocomposites were investigated. Viscosity and electrical surface resistivity of the nanocomposites showed minima at certain mixtures of GNP and CB in the epoxy resins.

Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

NASA Astrophysics Data System (ADS)

Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

2015-09-01

We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

Constructing a novel and safer energy storing system using a graphite cathode and a MoO 3 anode

NASA Astrophysics Data System (ADS)

Gunawardhana, Nanda; Park, Gum-Jae; Dimov, Nikolay; Thapa, Arjun Kumar; Nakamura, Hiroyoshi; Wang, Hongyu; Ishihara, Tatsumi; Yoshio, Masaki

A cell employing a graphite cathode and a molybdenum (VI) oxide (MoO 3) anode is investigated as a possible energy storage device. Graphite cathode allows raising the voltage well above the cathode materials of LIBs without causing safety issues. The bottom potential of this anode is 2.0 V vs. Li/Li +, which is well above the lithium plating potential. Pulse polarization experiment reveals that no lithium deposition occurs, which further enhances the safety of the graphite/MoO 3 full cell. Charge/discharge mechanism of this system results from intercalation and de-intercalation of the PF 6 - in the cathode (KS-6) and Li + in the anode (MoO 3). This mechanism is supported by in situ X-ray diffraction data of the graphite/MoO 3 cell recorded at various states of charge.

Conductive Composites Made Less Expensively

NASA Technical Reports Server (NTRS)

Gaier, James R.

2005-01-01

The use of electrically conductive composite structures for electrostatic dissipation, electromagnetic interference shielding, and ground return planes could save between 30 and 90 percent of the mass of the structure, in comparison to aluminum. One strategy that has been shown to make conducting composites effectively uses intercalated graphite fiber as the reinforcement. Intercalation--the insertion of guest atoms or molecules between the graphene planes--can lower the electrical resistivity of graphite fibers by as much as a factor of 10, without sacrificing mechanical or thermal properties.

High performance Li-ion sulfur batteries enabled by intercalation chemistry.

PubMed

Lv, Dongping; Yan, Pengfei; Shao, Yuyan; Li, Qiuyan; Ferrara, Seth; Pan, Huilin; Graff, Gordon L; Polzin, Bryant; Wang, Chongmin; Zhang, Ji-Guang; Liu, Jun; Xiao, Jie

2015-09-11

The unstable interface of lithium metal in high energy density Li sulfur (Li-S) batteries raises concerns of poor cycling, low efficiency and safety issues, which may be addressed by using intercalation types of anode. Herein, a new prototype of Li-ion sulfur battery with high performance has been demonstrated by coupling a graphite anode with a sulfur cathode (2 mA h cm(-2)) after successfully addressing the interface issue of graphite in an ether based electrolyte.

The structure of graphene oxide membranes in liquid water, ethanol and water-ethanol mixtures

NASA Astrophysics Data System (ADS)

Talyzin, Alexandr V.; Hausmaninger, Tomas; You, Shujie; Szabó, Tamás

2013-12-01

The structure of graphene oxide (GO) membranes was studied in situ in liquid solvents using synchrotron radiation X-ray diffraction in a broad temperature interval. GO membranes are hydrated by water similarly to precursor graphite oxide powders but intercalation of alcohols is strongly hindered, which explains why the GO membranes are permeated by water and not by ethanol. Insertion of ethanol into the membrane structure is limited to only one monolayer in the whole studied temperature range, in contrast to precursor graphite oxide powders, which are intercalated with up to two ethanol monolayers (Brodie) and four ethanol monolayers (Hummers). As a result, GO membranes demonstrate the absence of ``negative thermal expansion'' and phase transitions connected to insertion/de-insertion of alcohols upon temperature variations reported earlier for graphite oxide powders. Therefore, GO membranes are a distinct type of material with unique solvation properties compared to parent graphite oxides even if they are composed of the same graphene oxide flakes.The structure of graphene oxide (GO) membranes was studied in situ in liquid solvents using synchrotron radiation X-ray diffraction in a broad temperature interval. GO membranes are hydrated by water similarly to precursor graphite oxide powders but intercalation of alcohols is strongly hindered, which explains why the GO membranes are permeated by water and not by ethanol. Insertion of ethanol into the membrane structure is limited to only one monolayer in the whole studied temperature range, in contrast to precursor graphite oxide powders, which are intercalated with up to two ethanol monolayers (Brodie) and four ethanol monolayers (Hummers). As a result, GO membranes demonstrate the absence of ``negative thermal expansion'' and phase transitions connected to insertion/de-insertion of alcohols upon temperature variations reported earlier for graphite oxide powders. Therefore, GO membranes are a distinct type of material with unique solvation properties compared to parent graphite oxides even if they are composed of the same graphene oxide flakes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04631a

Nickel-Tin Electrode Materials for Nonaqueous Li-Ion Cells

NASA Technical Reports Server (NTRS)

Ehrlich, Grant M.; Durand, Christopher

2005-01-01

Experimental materials made from mixtures of nickel and tin powders have shown promise for use as the negative electrodes of rechargeable lithium-ion electrochemical power cells. During charging (or discharging) of a lithium-ion cell, lithium ions are absorbed into (or desorbed from, respectively) the negative electrode, typically through an intercalation or alloying process. The negative electrodes (for this purpose, designated as anodes) in state-of-the-art Li-ion cells are made of graphite, in which intercalation occurs. Alternatively, the anodes can be made from metals, in which alloying can occur. For reasons having to do with the electrochemical potential of intercalated lithium, metallic anode materials (especially materials containing tin) are regarded as safer than graphite ones; in addition, such metallic anode materials have been investigated in the hope of obtaining reversible charge/discharge capacities greater than those of graphite anodes. However, until now, each of the tin-containing metallic anode formulations tested has been found to be inadequate in some respect.

High Coulombic efficiency aluminum-ion battery using an AlCl3-urea ionic liquid analog electrolyte.

PubMed

Angell, Michael; Pan, Chun-Jern; Rong, Youmin; Yuan, Chunze; Lin, Meng-Chang; Hwang, Bing-Joe; Dai, Hongjie

2017-01-31

In recent years, impressive advances in harvesting renewable energy have led to a pressing demand for the complimentary energy storage technology. Here, a high Coulombic efficiency (∼99.7%) Al battery is developed using earth-abundant aluminum as the anode, graphite as the cathode, and a cheap ionic liquid analog electrolyte made from a mixture of AlCl 3 and urea in a 1.3:1 molar ratio. The battery displays discharge voltage plateaus around 1.9 and 1.5 V (average discharge = 1.73 V) and yielded a specific cathode capacity of ∼73 mAh g -1 at a current density of 100 mA g -1 (∼1.4 C). High Coulombic efficiency over a range of charge-discharge rates and stability over ∼150-200 cycles was easily demonstrated. In situ Raman spectroscopy clearly showed chloroaluminate anion intercalation/deintercalation of graphite (positive electrode) during charge-discharge and suggested the formation of a stage 2 graphite intercalation compound when fully charged. Raman spectroscopy and NMR suggested the existence of AlCl 4 - , Al 2 Cl 7 - anions and [AlCl 2 ·(urea) n ] + cations in the AlCl 3 /urea electrolyte when an excess of AlCl 3 was present. Aluminum deposition therefore proceeded through two pathways, one involving Al 2 Cl 7 - anions and the other involving [AlCl 2 ·(urea) n ] + cations. This battery is a promising prospect for a future high-performance, low-cost energy storage device.

Enhanced Thermal Diffusion of Li in Graphite by Alternating Vertical Electric Field: A Hybrid Quantum-Classical Simulation Study

NASA Astrophysics Data System (ADS)

Ohba, Nobuko; Ogata, Shuji; Tamura, Tomoyuki; Kobayashi, Ryo; Yamakawa, Shunsuke; Asahi, Ryoji

2012-02-01

Enhancing the diffusivity of the Li ion in a Li-graphite intercalation compound that has been used as a negative electrode in the Li-ion rechargeable battery, is important in improving both the recharging speed and power of the battery. In the compound, the Li ion creates a long-range stress field around itself by expanding the interlayer spacing of graphite. We advance the hybrid quantum-classical simulation code to include the external electric field in addition to the long-range stress field by first-principles simulation. In the hybrid code, the quantum region selected adaptively around the Li ion is treated using the real-space density-functional theory for electrons. The rest of the system is described with an empirical interatomic potential that includes the term relating to the dispersion force between the C atoms in different layers. Hybrid simulation runs for Li dynamics in graphite are performed at 423 K under various settings of the amplitude and frequency of alternating electric fields perpendicular to C-layers. We find that the in-plane diffusivity of the Li ion is enhanced significantly by the electric field if the amplitude is larger than 0.2 V/Å within its order and the frequency is as high as 1.7 THz. The microscopic mechanisms of the enhancement are explained.

A reactive force field study of Li/C systems for electrical energy storage

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

Raju, Muralikrishna; Ganesh, P.; Kent, Paul R. C.

Graphitic carbon is still the most ubiquitously used anode material in Li-ion batteries. In spite of its ubiquity, there are few theoretical studies that fully capture the energetics and kinetics of Li in graphite and related nanostructures at experimentally relevant length, time-scales, and Li-ion concentrations. In this paper, we describe the development and application of a ReaxFF reactive force field to describe Li interactions in perfect and defective carbon-based materials using atomistic simulations. We develop force field parameters for Li–C systems using van der Waals-corrected density functional theory (DFT). Grand canonical Monte Carlo simulations of Li intercalation in perfect graphitemore » with this new force field not only give a voltage profile in good agreement with known experimental and DFT results but also capture the in-plane Li ordering and interlayer separations for stage I and II compounds. In defective graphite, the ratio of Li/C (i.e., the capacitance increases and voltage shifts) both in proportion to the concentration of vacancy defects and metallic lithium is observed to explain the lithium plating seen in recent experiments. We also demonstrate the robustness of the force field by simulating model carbon nanostructures (i.e., both 0D and 1D structures) that can be potentially used as battery electrode materials. Whereas a 0D defective onion-like carbon facilitates fast charging/discharging rates by surface Li adsorption, a 1D defect-free carbon nanorod requires a critical density of Li for intercalation to occur at the edges. Our force field approach opens the opportunity for studying energetics and kinetics of perfect and defective Li/C structures containing thousands of atoms as a function of intercalation. As a result, this is a key step toward modeling of realistic carbon materials for energy applications.« less

A reactive force field study of Li/C systems for electrical energy storage

DOE PAGES

Raju, Muralikrishna; Ganesh, P.; Kent, Paul R. C.; ...

2015-04-02

Graphitic carbon is still the most ubiquitously used anode material in Li-ion batteries. In spite of its ubiquity, there are few theoretical studies that fully capture the energetics and kinetics of Li in graphite and related nanostructures at experimentally relevant length, time-scales, and Li-ion concentrations. In this paper, we describe the development and application of a ReaxFF reactive force field to describe Li interactions in perfect and defective carbon-based materials using atomistic simulations. We develop force field parameters for Li–C systems using van der Waals-corrected density functional theory (DFT). Grand canonical Monte Carlo simulations of Li intercalation in perfect graphitemore » with this new force field not only give a voltage profile in good agreement with known experimental and DFT results but also capture the in-plane Li ordering and interlayer separations for stage I and II compounds. In defective graphite, the ratio of Li/C (i.e., the capacitance increases and voltage shifts) both in proportion to the concentration of vacancy defects and metallic lithium is observed to explain the lithium plating seen in recent experiments. We also demonstrate the robustness of the force field by simulating model carbon nanostructures (i.e., both 0D and 1D structures) that can be potentially used as battery electrode materials. Whereas a 0D defective onion-like carbon facilitates fast charging/discharging rates by surface Li adsorption, a 1D defect-free carbon nanorod requires a critical density of Li for intercalation to occur at the edges. Our force field approach opens the opportunity for studying energetics and kinetics of perfect and defective Li/C structures containing thousands of atoms as a function of intercalation. As a result, this is a key step toward modeling of realistic carbon materials for energy applications.« less

Large discharge capacity from carbon electrodes in sulfuric acid with oxidant

NASA Astrophysics Data System (ADS)

Inagaki, M.; Iwashita, N.

The discharge performance of the graphite intercalation compounds in sulfuric acid containing nitric acid (H 2SO 4-GICs) was studied by focusing on the effects of oxidant and carbon nanotexture. A large discharge capacity from H 2SO 4-GICs synthesized by using an excess amount of HNO 3, more than 150 times of the theoretical value (93 mAh/g carbon), was obtained depending on the amount of oxidant added, the discharge current, and the nanotexture of carbon electrode. The experimental results are explained in terms of competition between the de-intercalation of sulfuric acid due to galvanostatic reduction and the re-intercalation due to chemical oxidation by HN03 during discharging. However, a subsidiary reaction decreases the effective amount of HNO 3 on the discharge by a small current and also on the cycle of chemical charging and electrochemical discharging. The oxidant KMnO 4 gave only a little larger capacity for discharge than the theoretical one, because it was reduced to the manganese oxide precipitates during the oxidation of the carbon electrode.

New Materials for EMI Shielding

NASA Technical Reports Server (NTRS)

Gaier, James R.

1999-01-01

Graphite fibers intercalated with bromine or similar mixed halogen compounds have substantially lower resistivity than their pristine counterparts, and thus should exhibit higher shielding effectiveness against electromagnetic interference. The mechanical and thermal properties are nearly unaffected, and the shielding of high energy x-rays and gamma rays is substantially increased. Characterization of the resistivity of the composite materials is subtle, but it is clear that the composite resistivity is substantially lowered. Shielding effectiveness calculations utilizing a simple rule of mixtures model yields results that are consistent with available data on these materials.

Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

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

Kumaran, R.; Alagar, M.; Dinesh Kumar, S.

We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDFmore » matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.« less

Bulk evidence for single-Gap s-wave superconductivity in the intercalated graphite superconductor C6Yb.

PubMed

Sutherland, Mike; Doiron-Leyraud, Nicolas; Taillefer, Louis; Weller, Thomas; Ellerby, Mark; Saxena, S S

2007-02-09

We report measurements of the in-plane electrical resistivity rho and thermal conductivity kappa of the intercalated graphite superconductor C6Yb down to temperatures as low as Tc/100. When a field is applied along the c axis, the residual electronic linear term kappa0/T evolves in an exponential manner for Hc1

Treasure Na-ion anode from trash coke by adept electrolyte selection

NASA Astrophysics Data System (ADS)

Cabello, Marta; Chyrka, Taras; Klee, Rafael; Aragón, María J.; Bai, Xue; Lavela, Pedro; Vasylchenko, Gennadiy M.; Alcántara, Ricardo; Tirado, José L.; Ortiz, Gregorio F.

2017-04-01

Converting 'trash' waste residua to active functional materials 'treasure' with high added value is being regarded as a promising way to achieve the sustainable energy demands. Carbonaceous materials cannot insert sodium except when graphite co-intercalates solvents such as diglyme. Here, we show that petroleum coke and shale coke annealed at different temperatures can also insert sodium by reversible intercalation phenomena in a diglyme-based electrolyte. The structural and morphological studies will reveal significant differences justifying their distinct electrochemical behavior. Galvanostatic tests exhibit a flat plateau at about 0.7 V ascribable to the reversible reaction. At the end of the discharge, a Stage-I ternary intercalation compound is detected. Two diglyme molecules are co-intercalated per alkali ion, as evidenced by 1-D Patterson diagrams, FTIR and TGA analyses. The full sodium-ion cell made with P-2500/NaPF6(diglyme)/Na3V2(PO4)3 delivered an initial reversible capacity of 75 mA h g-1 at C rate and an average potential of 2.7 V. Thus, the full cell provides an energy density of 202 W h kg-1. This sodium-ion system can be considered a promising power source that encourages the potential use of low-cost energy storage systems.

Comparison of reduction products from graphite oxide and graphene oxide for anode applications in lithium-ion batteries and sodium-ion batteries.

PubMed

Sun, Yige; Tang, Jie; Zhang, Kun; Yuan, Jinshi; Li, Jing; Zhu, Da-Ming; Ozawa, Kiyoshi; Qin, Lu-Chang

2017-02-16

Hydrazine-reduced graphite oxide and graphene oxide were synthesized to compare their performances as anode materials in lithium-ion batteries and sodium-ion batteries. Reduced graphite oxide inherits the layer structure of graphite, with an average spacing between neighboring layers (d-spacing) of 0.374 nm; this exceeds the d-spacing of graphite (0.335 nm). The larger d-spacing provides wider channels for transporting lithium ions and sodium ions in the material. We showed that reduced graphite oxide as an anode in lithium-ion batteries can reach a specific capacity of 917 mA h g -1 , which is about three times of 372 mA h g -1 , the value expected for the LiC 6 structures on the electrode. This increase is consistent with the wider d-spacing, which enhances lithium intercalation and de-intercalation on the electrodes. The electrochemical performance of the lithium-ion batteries and sodium-ion batteries with reduced graphite oxide anodes show a noticeable improvement compared to those with reduced graphene oxide anodes. This improvement indicates that reduced graphite oxide, with larger interlayer spacing, has fewer defects and is thus more stable. In summary, we found that reduced graphite oxide may be a more favorable form of graphene for the fabrication of electrodes for lithium-ion and sodium-ion batteries and other energy storage devices.

High Coulombic efficiency aluminum-ion battery using an AlCl3-urea ionic liquid analog electrolyte

PubMed Central

Angell, Michael; Pan, Chun-Jern; Rong, Youmin; Yuan, Chunze; Lin, Meng-Chang; Hwang, Bing-Joe; Dai, Hongjie

2017-01-01

In recent years, impressive advances in harvesting renewable energy have led to a pressing demand for the complimentary energy storage technology. Here, a high Coulombic efficiency (∼99.7%) Al battery is developed using earth-abundant aluminum as the anode, graphite as the cathode, and a cheap ionic liquid analog electrolyte made from a mixture of AlCl3 and urea in a 1.3:1 molar ratio. The battery displays discharge voltage plateaus around 1.9 and 1.5 V (average discharge = 1.73 V) and yielded a specific cathode capacity of ∼73 mAh g−1 at a current density of 100 mA g−1 (∼1.4 C). High Coulombic efficiency over a range of charge–discharge rates and stability over ∼150–200 cycles was easily demonstrated. In situ Raman spectroscopy clearly showed chloroaluminate anion intercalation/deintercalation of graphite (positive electrode) during charge–discharge and suggested the formation of a stage 2 graphite intercalation compound when fully charged. Raman spectroscopy and NMR suggested the existence of AlCl4−, Al2Cl7− anions and [AlCl2·(urea)n]+ cations in the AlCl3/urea electrolyte when an excess of AlCl3 was present. Aluminum deposition therefore proceeded through two pathways, one involving Al2Cl7− anions and the other involving [AlCl2·(urea)n]+ cations. This battery is a promising prospect for a future high-performance, low-cost energy storage device. PMID:28096353

Intercalated graphitic carbon nitride: a fascinating two-dimensional nanomaterial for an ultra-sensitive humidity nanosensor

NASA Astrophysics Data System (ADS)

Zhang, Zhenyi; Huang, Jindou; Yuan, Qing; Dong, Bin

2014-07-01

We develop a novel humidity nanosensor based on intercalated graphitic carbon nitride (g-C3N4) nanosheets fabricated by a facile thermal polymerization of common urea in the presence of LiCl as the intercalated guest under air and ambient pressure. The response and recovery times of an optimal nanosensor can reach ~0.9 s and ~1.4 s, respectively, which are superior to most of the traditional oxide ceramic-based humidity nanosensors tested under similar conditions. By combining with the theoretical calculations, it is proposed that the ultrafast response-recovery time for this nanosensor is attributed to their unique 2D intercalated nanostructure by which Li species linked with the ``nitrogen pots'' of g-C3N4 can make the protons conduct in the first adsorbed water layer. Meanwhile, the physically adsorbed water on the surface of LiCl-intercalated g-C3N4 nanosheets can be desorbed rapidly at a relative lower RH environment due to their high adsorption energy and the strong diffusion effect of water molecules.We develop a novel humidity nanosensor based on intercalated graphitic carbon nitride (g-C3N4) nanosheets fabricated by a facile thermal polymerization of common urea in the presence of LiCl as the intercalated guest under air and ambient pressure. The response and recovery times of an optimal nanosensor can reach ~0.9 s and ~1.4 s, respectively, which are superior to most of the traditional oxide ceramic-based humidity nanosensors tested under similar conditions. By combining with the theoretical calculations, it is proposed that the ultrafast response-recovery time for this nanosensor is attributed to their unique 2D intercalated nanostructure by which Li species linked with the ``nitrogen pots'' of g-C3N4 can make the protons conduct in the first adsorbed water layer. Meanwhile, the physically adsorbed water on the surface of LiCl-intercalated g-C3N4 nanosheets can be desorbed rapidly at a relative lower RH environment due to their high adsorption energy and the strong diffusion effect of water molecules. Electronic supplementary information (ESI) available: Fig. S1-S8 and Table S1 including SEM, TEM and theoretical calculations. See DOI: 10.1039/c4nr01570c

Atomic intercalation to measure adhesion of graphene on graphite

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

Wang, Jun; Sorescu, Dan C.; Jeon, Seokmin

The interest in mechanical properties of layered and 2D materials has reemerged in light of device concepts that take advantage of flexing, adhesion and friction in such systems. Here we provide an effective measurement of the nanoscale elastic adhesion of a graphene sheet atop highly ordered pyrolytic graphite (HOPG) based on the analysis of atomic intercalates in graphite. Atomic intercalation is carried out using conventional ion sputtering, creating blisters in the top-most layer of the HOPG surface. Scanning tunneling microscopy coupled with image analysis and density functional theory are used to reconstruct the atomic positions and the strain map withinmore » the deformed graphene sheet, as well as to demonstrate subsurface diffusion of the ions creating such blisters. To estimate the adhesion energy we invoke an analytical model originally devised for macroscopic deformations of graphene. This model yields a value of 0.221 ± 0.011 J/m -2 for the adhesion energy of graphite, which is in surprisingly good agreement with reported experimental and theoretical values. This implies that macroscopic mechanical properties of graphene scale down to at least a few nanometers length. The simplicity of our method, compared to the macroscale characterization, enables analysis of elastic mechanical properties in two-dimensional layered materials and provides a unique opportunity to investigate the local variability of mechanical properties on the nanoscale.« less

Atomic intercalation to measure adhesion of graphene on graphite

DOE PAGES

Wang, Jun; Sorescu, Dan C.; Jeon, Seokmin; ...

2016-10-31

The interest in mechanical properties of layered and 2D materials has reemerged in light of device concepts that take advantage of flexing, adhesion and friction in such systems. Here we provide an effective measurement of the nanoscale elastic adhesion of a graphene sheet atop highly ordered pyrolytic graphite (HOPG) based on the analysis of atomic intercalates in graphite. Atomic intercalation is carried out using conventional ion sputtering, creating blisters in the top-most layer of the HOPG surface. Scanning tunneling microscopy coupled with image analysis and density functional theory are used to reconstruct the atomic positions and the strain map withinmore » the deformed graphene sheet, as well as to demonstrate subsurface diffusion of the ions creating such blisters. To estimate the adhesion energy we invoke an analytical model originally devised for macroscopic deformations of graphene. This model yields a value of 0.221 ± 0.011 J/m -2 for the adhesion energy of graphite, which is in surprisingly good agreement with reported experimental and theoretical values. This implies that macroscopic mechanical properties of graphene scale down to at least a few nanometers length. The simplicity of our method, compared to the macroscale characterization, enables analysis of elastic mechanical properties in two-dimensional layered materials and provides a unique opportunity to investigate the local variability of mechanical properties on the nanoscale.« less

Sorbents and Mechanisms of Removal

DTIC Science & Technology

2010-08-21

Interactions of Ammonia with Pillared Graphite Oxide Intercalated with Aluminium and Zirconium Polyoxycations Mykola Seredych and T. J. Bandosz ,J...Adsorbents Containing Silver Nanoparticles M. Seredych, S. Bashkova, R. Pietrzak, T.J. Bandosz Langmuir, 26 (2010) 9457-9464 35. Graphite Oxide /Zr(OH)4...Small Molecule Toxic Gases on Graphite Oxide Based Adsorbents Adorbent Wokshop Camille Petit, Roberts Pietrzak and T.J. Bandosz Seattle, WA, July 12-14

Superconducting Continuous Graphene Fibers via Calcium Intercalation.

PubMed

Liu, Yingjun; Liang, Hui; Xu, Zhen; Xi, Jiabin; Chen, Genfu; Gao, Weiwei; Xue, Mianqi; Gao, Chao

2017-04-25

Superconductors are important materials in the field of low-temperature magnet applications and long-distance electrical power transmission systems. Besides metal-based superconducting materials, carbon-based superconductors have attracted considerable attention in recent years. Up to now, five allotropes of carbon, including diamond, graphite, C 60 , CNTs, and graphene, have been reported to show superconducting behavior. However, most of the carbon-based superconductors are limited to small size and discontinuous phases, which inevitably hinders further application in macroscopic form. Therefore, it raises a question of whether continuously carbon-based superconducting wires could be accessed, which is of vital importance from viewpoints of fundamental research and practical application. Here, inspired by superconducting graphene, we successfully fabricated flexible graphene-based superconducting fibers via a well-established calcium (Ca) intercalation strategy. The resultant Ca-intercalated graphene fiber (Ca-GF) shows a superconducting transition at ∼11 K, which is almost 2 orders of magnitude higher than that of early reported alkali metal intercalated graphite and comparable to that of commercial superconducting NbTi wire. The combination of lightness and easy scalability makes Ca-GF highly promising as a lightweight superconducting wire.

Structure and Properties of Intercalated Graphite Fiber-Polymer Composites.

DTIC Science & Technology

1983-07-07

resistivities of all com- nal graphite. Experimental evidence (1,2) in- plexes were determined both before and after dicated that the electrophilic N02...others show promise as fluorinating agents in chemical synthesisI21. At this point, however, so little is Known of processing parameters and long-term

The milling of pristine and brominated P-100 graphite fibers

NASA Technical Reports Server (NTRS)

Dillehay, M. E.; Gaier, J. R.

1986-01-01

Techniques were developed for the ball milling of pristine and brominated P-100 graphite fibers. Because of the lubrication properties of graphite, large ball loads (50 percent by volume) were required. Use of 2-propanol as a milling medium enhanced the efficiency of the process. Milled brominated P-100 fibers had resistivities which were indistinguishable from milled pristine P-100 fibers. Apparent loss of bromine from the brominated fibers suggests that bromine would not be the intercalate of choice in applications where milled fibers of this type are required. Other intercalates which do not degas may be more appropriate for a milled fiber application. These same results, however, do provide evidence that bromine molecules leave the fiber surface when removed from overpressure of bromine. While exploring possible solvent media for milling purposes, it was found that brominated fibers are stable in a wide variety of organic solvents.

Lithium loss in the solid electrolyte interphase: Lithium quantification of aged lithium ion battery graphite electrodes by means of laser ablation inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectroscopy

NASA Astrophysics Data System (ADS)

Schwieters, Timo; Evertz, Marco; Mense, Maximilian; Winter, Martin; Nowak, Sascha

2017-07-01

In this work we present a new method using LA-ICP-MS to quantitatively determine the lithium content in aged graphite electrodes of a lithium ion battery (LIB) by performing total depth profiling. Matrix matched solid external standards are prepared using a solid doping approach to avoid elemental fractionation effects during the measurement. The results are compared and matched to the established ICP-OES technique for bulk quantification after performing a microwave assisted acid digestion. The method is applied to aged graphite electrodes in order to determine the lithium immobilization (= "Li loss") in the solid electrolyte interphase after the first cycle of formation. For this, different samples including a reference sample are created to obtain varying thicknesses of the SEI covering the electrode particles. By applying defined charging voltages, an initial lithiation process is performed to obtain specific graphite intercalation compounds (GICs, with target stoichiometries of LiC30, LiC18, LiC12 and LiC6). Afterwards, the graphite electrode is completely discharged to obtain samples without mobile, thus active lithium in its lattice. Taking the amount of lithium into account which originates from the residues of the LiPF6 (dissolved in the carbon components containing electrolyte), it is possible to subtract the amount of lithium in the SEI.

Nano-scaled top-down of bismuth chalcogenides based on electrochemical lithium intercalation

NASA Astrophysics Data System (ADS)

Chen, Jikun; Zhu, Yingjie; Chen, Nuofu; Liu, Xinling; Sun, Zhengliang; Huang, Zhenghong; Kang, Feiyu; Gao, Qiuming; Jiang, Jun; Chen, Lidong

2011-12-01

A two-step method has been used to fabricate nano-particles of layer-structured bismuth chalcogenide compounds, including Bi2Te3, Bi2Se3, and Bi2Se0.3Te2.7, through a nano-scaled top-down route. In the first step, lithium (Li) atoms are intercalated between the van der Waals bonded quintuple layers of bismuth chalcogenide compounds by controllable electrochemical process inside self-designed lithium ion batteries. And in the second step, the Li intercalated bismuth chalcogenides are subsequently exposed to ethanol, in which process the intercalated Li atoms would explode like atom-scaled bombs to exfoliate original microscaled powder into nano-scaled particles with size around 10 nm. The influence of lithium intercalation speed and amount to three types of bismuth chalcogenide compounds are compared and the optimized intercalation conditions are explored. As to maintain the phase purity of the final nano-particle product, the intercalation lithium amount should be well controlled in Se contained bismuth chalcogenide compounds. Besides, compared with binary bismuth chalcogenide compound, lower lithium intercalation speed should be applied in ternary bismuth chalcogenide compound.

Tunable Graphitic Carbon Nano-Onions Development in Carbon Nanofibers for Multivalent Energy Storage

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

Schwarz, Haiqing L.

2016-01-01

We developed a novel porous graphitic carbon nanofiber material using a synthesis strategy combining electrospinning and catalytic graphitization. RF hydrogel was used as carbon precursors, transition metal ions were successfully introduced into the carbon matrix by binding to the carboxylate groups of a resorcinol derivative. Transition metal particles were homogeneously distributed throughout the carbon matrix, which are used as in-situ catalysts to produce graphitic fullerene-like nanostructures surrounding the metals. The success design of graphitic carbons with enlarged interlayer spacing will enable the multivalent ion intercalation for the development of multivalent rechargeable batteries.

Physics and chemistry of MoS2 intercalation compounds

NASA Technical Reports Server (NTRS)

Woollam, J. A.; Somoano, R. B.

1977-01-01

An investigation is made of the physics and chemistry of MoS2 intercalation compounds. These compounds may be separated into two groups according to their stoichiometry, structure and superconducting properties. The first group consists of Na, Ca, and Sr intercalates, and the second group consists of K, Rb, and Cs intercalates. Particular attention is given to the structure of the electronic energy band and to the normal state and superconducting properties of these compounds.

Synthesis and characterization of montmorillonite clay intercalated with molecular magnetic compounds

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

Martins, Marcel G.; Martins, Daniel O.T.A.; Carvalho, Beatriz L.C. de

2015-08-15

In this work montmorillonite (MMT) clay, whose matrix was modified with an ammonium salt (hexadecyltrimethylammonium bromide – CTAB), was employed as an inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange: a nitronyl nitroxide derivative 2-[4-(N-ethyl)-pyridinium]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (p-EtRad{sup +}) and two binuclear coordination compounds, [Ni(valpn)Ln]{sup 3+}, where H{sub 2}valpn stands for 1,3-propanediyl-bis(2-iminomethylene-6-methoxy-phenol), and Ln=Gd{sup III}; Dy{sup III}. The pristine MMT and the intercalated materials were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurements. The X-ray diffraction data analysis showed an increase of the interlamellar spacemore » of the intercalated MMT, indicating the intercalation of the magnetic compounds. Furthermore, the magnetic properties of the hybrid compounds were investigated, showing similar behavior as the pure magnetic guest species. - Graphical abstract: Montmorillonite clay was employed as inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange - Highlights: • Montmorillonite was employed as a host material. • Three molecular magnetic compounds were intercalated through ion exchange. • The compounds were successful intercalated maintaining the layered structure. • The hybrid materials exhibited similar magnetic behavior as the pure magnetic guest.« less

Vaporization and atomization of uranium in a graphite tube electrothermal vaporizer: a mechanistic study using electrothermal vaporization inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Goltz, D. M.; Grégoire, D. C.; Byrne, J. P.; Chakrabarti, C. L.

1995-07-01

The mechanism of vaporization and atomization of U in a graphite tube electrothermal vaporizer was studied using graphite furnace atomic absorption spectrometry (GFAAS) and electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). Graphite furnace AAS studies indicate U atoms are formed at temperatures above 2400°C. Using ETV-ICP-MS, an appearance temperature of 1100°C was obtained indicating that some U vaporizes as U oxide. Although U carbides form at temperatures above 2000°C, ETV-ICP-MS studies show that they do not vaporize until 2600°C. In the temperature range between 2200°C and 2600°C, U atoms in GFAAS are likely formed by thermal dissociation of U oxide, whereas at higher temperatures, U atoms are formed via thermal dissociation of U carbide. The origin of U signal suppression in ETV-ICP-MS by NaCl was also investigated. At temperatures above 2000°C, signal suppression may be caused by the accelerated rate of formation of carbide species while at temperatures below 2000°C, the presence of NaCl may cause intercalation of the U in the graphite layers resulting in partial retention of U during the vaporization step. The use of 0.3% freon-23 (CHF 3) mixed with the argon carrier gas was effective in preventing the intercalation of U in graphite and U carbide formation at 2700°C.

Recent Advances in Preparation, Structure, Properties and Applications of Graphite Oxide.

PubMed

Srivastava, Suneel Kumar; Pionteck, Jürgen

2015-03-01

Graphite oxide, also referred as graphitic oxide or graphitic acid, is an oxidized bulk product of graphite with a variable composition. However, it did not receive immense attention until it was identified as an important and easily obtainable precursor for the preparation of graphene. This inspired many researchers to explore facts related to graphite oxide in exploiting its fascinating features. The present article culminates up-dated review on different preparative methods, morphology and characterization of physical/chemical properties of graphite oxide by XRD, XPS, FTIR, Raman, NMR, UV-visible, and DRIFT analyses. Finally, recent developments on intercalation and applications of GO in multifaceted areas of catalysis, sensor, supercapacitors, water purification, hydrogen storage and magnetic shielding etc. has also been reviewed.

Safe and recyclable lithium-ion capacitors using sacrificial organic lithium salt.

PubMed

Jeżowski, P; Crosnier, O; Deunf, E; Poizot, P; Béguin, F; Brousse, T

2018-02-01

Lithium-ion capacitors (LICs) shrewdly combine a lithium-ion battery negative electrode capable of reversibly intercalating lithium cations, namely graphite, together with an electrical double-layer positive electrode, namely activated carbon. However, the beauty of this concept is marred by the lack of a lithium-cation source in the device, thus requiring a specific preliminary charging step. The strategies devised thus far in an attempt to rectify this issue all present drawbacks. Our research uncovers a unique approach based on the use of a lithiated organic material, namely 3,4-dihydroxybenzonitrile dilithium salt. This compound can irreversibly provide lithium cations to the graphite electrode during an initial operando charging step without any negative effects with respect to further operation of the LIC. This method not only restores the low CO 2 footprint of LICs, but also possesses far-reaching potential with respect to designing a wide range of greener hybrid devices based on other chemistries, comprising entirely recyclable components.

Dissecting anode swelling in commercial lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Ningxin; Tang, Huaqiong

2012-11-01

An innovative method is applied to investigate anode swelling during electrochemical processes in commercial lithium-ion batteries. Cathode surface is partially covered with a piece of paste to block the transportation of lithium ion from active material during charging/discharging, and the corresponding part on the anode film shows no formation of Li-graphite compounds during different electrochemical processes, which is confirmed by XRD analysis. The increases of anode thickness within and outside lithiated zone are measured, and defined as electrochemical swelling and physical swelling respectively. The microscopic lattice expansion of graphite due to lithiation process correlates to mesoscopic electrochemical swelling synchronically, while physical swelling tends to decrease steadily with time. The relationship among the microscopic stress due to lithium-ion intercalation, the mesoscopic stress resulting in anode swelling, and the macroscopic rippling of pouch cell after a large number of cycle test, is analyzed and correlated in terms of stress evolution across different scales, and suggestions for solving anode swelling are provided.

Safe and recyclable lithium-ion capacitors using sacrificial organic lithium salt

NASA Astrophysics Data System (ADS)

Jeżowski, P.; Crosnier, O.; Deunf, E.; Poizot, P.; Béguin, F.; Brousse, T.

2018-02-01

Lithium-ion capacitors (LICs) shrewdly combine a lithium-ion battery negative electrode capable of reversibly intercalating lithium cations, namely graphite, together with an electrical double-layer positive electrode, namely activated carbon. However, the beauty of this concept is marred by the lack of a lithium-cation source in the device, thus requiring a specific preliminary charging step. The strategies devised thus far in an attempt to rectify this issue all present drawbacks. Our research uncovers a unique approach based on the use of a lithiated organic material, namely 3,4-dihydroxybenzonitrile dilithium salt. This compound can irreversibly provide lithium cations to the graphite electrode during an initial operando charging step without any negative effects with respect to further operation of the LIC. This method not only restores the low CO2 footprint of LICs, but also possesses far-reaching potential with respect to designing a wide range of greener hybrid devices based on other chemistries, comprising entirely recyclable components.

Single-Wall Carbon Nanotube Anodes for Lithium Cells

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Raffaelle, Ryne; Gennett, Tom; Kumta, Prashant; Maranchi, Jeff; Heben, Mike

2006-01-01

In recent experiments, highly purified batches of single-wall carbon nanotubes (SWCNTs) have shown promise as superior alternatives to the graphitic carbon-black anode materials heretofore used in rechargeable thin-film lithium power cells. The basic idea underlying the experiments is that relative to a given mass of graphitic carbon-black anode material, an equal mass of SWCNTs can be expected to have greater lithium-storage and charge/discharge capacities. The reason for this expectation is that whereas the microstructure and nanostructure of a graphitic carbon black is such as to make most of the interior of the material inaccessible for intercalation of lithium, a batch of SWCNTs can be made to have a much more open microstructure and nanostructure, such that most of the interior of the material is accessible for intercalation of lithium. Moreover, the greater accessibility of SWCNT structures can be expected to translate to greater mobilities for ion-exchange processes and, hence, an ability to sustain greater charge and discharge current densities.

Atomic intercalation to measure adhesion of graphene on graphite

PubMed Central

Wang, Jun; Sorescu, Dan C.; Jeon, Seokmin; Belianinov, Alexei; Kalinin, Sergei V.; Baddorf, Arthur P.; Maksymovych, Petro

2016-01-01

The interest in mechanical properties of two-dimensional materials has emerged in light of new device concepts taking advantage of flexing, adhesion and friction. Here we demonstrate an effective method to measure adhesion of graphene atop highly ordered pyrolytic graphite, utilizing atomic-scale ‘blisters' created in the top layer by neon atom intercalates. Detailed analysis of scanning tunnelling microscopy images is used to reconstruct atomic positions and the strain map within the deformed graphene layer, and demonstrate the tip-induced subsurface translation of neon atoms. We invoke an analytical model, originally devised for graphene macroscopic deformations, to determine the graphite adhesion energy of 0.221±0.011 J m−2. This value is in excellent agreement with reported macroscopic values and our atomistic simulations. This implies mechanical properties of graphene scale down to a few-nanometre length. The simplicity of our method provides a unique opportunity to investigate the local variability of nanomechanical properties in layered materials. PMID:27796294

Controlled release formulation of an anti-depression drug based on a L-phenylalanate-zinc layered hydroxide intercalation compound

NASA Astrophysics Data System (ADS)

Hashim, Norhayati; Sharif, Sharifah Norain Mohd; Isa, Illyas Md; Hamid, Shahidah Abdul; Hussein, Mohd Zobir; Bakar, Suriani Abu; Mamat, Mazidah

2017-06-01

The intercalation of L-phenylalanate (LP) into the interlayer gallery of zinc layered hydroxide (ZLH) has been successfully executed using a simple direct reaction method. The synthesised intercalation compound, zinc layered hydroxide-L-phenylalanate (ZLH-LP), was characterised using PXRD, FTIR, CHNS, ICP-OES, TGA/DTG, FESEM and TEM. The PXRD patterns of the intercalation compound demonstrate an intense and symmetrical peak, indicating a well-ordered crystalline layered structure. The appearance of an intercalation peak at a low angle of 2θ with a basal spacing of 16.3 Å, signifies the successful intercalation of the L-phenylalanate anion into the interlayer gallery of the host. The intercalation is also validated by FTIR spectroscopy and CHNS elemental analysis. Thermogravimetric analysis confirms that the ZLH-LP intercalation compound has higher thermal stability than the pristine L-phenylalanine. The observed percentage of L-phenylalanate accumulated release varies in each release media, with 84.5%, 79.8%, 63.8% and 61.8% release in phosphate buffer saline (PBS) solution at pH 4.8, deionised water, PBS solution at pH 7.4 and NaCl solution, respectively. The release behaviour of LP from its intercalation compounds in deionised water and PBS solution at pH 4.8 follows pseudo second order, whereas in NaCl solution and PBS solution at pH 7.4, it follows the parabolic diffusion model. This study shows that the synthesised ZLH-LP intercalation compound can be used for the formation of a new generation of materials for targeted drug release with controlled release properties.

Synthesis of (cinnamate-zinc layered hydroxide) intercalation compound for sunscreen application

PubMed Central

2013-01-01

Background Zinc layered hydroxide (ZLH) intercalated with cinnamate, an anionic form of cinnamic acid (CA), an efficient UVA and UVB absorber, have been synthesized by direct method using zinc oxide (ZnO) and cinnamic acid as the precursor. Results The resulting obtained intercalation compound, ZCA, showed a basal spacing of 23.9 Å as a result of cinnamate intercalated in a bilayer arrangement between the interlayer spaces of ZLH with estimated percentage loading of cinnamate of about 40.4 % w/w. The UV–vis absorption spectrum of the intercalation compound showed excellent UVA and UVB absorption ability. Retention of cinnamate in ZLH interlayers was tested against media usually came across with sunscreen usage to show low release over an extended period of time. MTT assay of the intercalation compound on human dermal fibroblast (HDF) cells showed cytotoxicity of ZCA to be concentration dependent and is overall less toxic than its precursor, ZnO. Conclusions (Cinnamate-zinc layered hydroxide) intercalation compound is suitable to be used as a safe and effective sunscreen with long UV protection effect. PMID:23383738

Evaluation of Carbon Anodes for Rechargeable Lithium Cells

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

Alkali metal intercalates of molybdenum disulfide.

NASA Technical Reports Server (NTRS)

Somoano, R. B.; Hadek, V.; Rembaum, A.

1973-01-01

Study of some of the physicochemical properties of compounds obtained by subjecting natural molybdenite and single crystals of molybdenum disulfide grown by chemical vapor transport to intercalation with the alkali group of metals (Li, Na, K, Rb, and Cs) by means of the liquid ammonia technique. Reported data and results include: (1) the intercalation of the entire alkali metal group, (2) stoichiometries and X-ray data on all of the compounds, and (3) superconductivity data for all the intercalation compounds.

Photoelectron Holographic Atomic Arrangement Imaging of Cleaved Bimetal-intercalated Graphite Superconductor Surface

PubMed Central

Matsui, Fumihiko; Eguchi, Ritsuko; Nishiyama, Saki; Izumi, Masanari; Uesugi, Eri; Goto, Hidenori; Matsushita, Tomohiro; Sugita, Kenji; Daimon, Hiroshi; Hamamoto, Yuji; Hamada, Ikutaro; Morikawa, Yoshitada; Kubozono, Yoshihiro

2016-01-01

From the C 1s and K 2p photoelectron holograms, we directly reconstructed atomic images of the cleaved surface of a bimetal-intercalated graphite superconductor, (Ca, K)C8, which differed substantially from the expected bulk crystal structure based on x-ray diffraction (XRD) measurements. Graphene atomic images were collected in the in-plane cross sections of the layers 3.3 Å and 5.7 Å above the photoelectron emitter C atom and the stacking structures were determined as AB- and AA-type, respectively. The intercalant metal atom layer was found between two AA-stacked graphenes. The K atomic image revealing 2 × 2 periodicity, occupying every second centre site of C hexagonal columns, was reconstructed, and the Ca 2p peak intensity in the photoelectron spectra of (Ca, K)C8 from the cleaved surface was less than a few hundredths of the K 2p peak intensity. These observations indicated that cleavage preferentially occurs at the KC8 layers containing no Ca atoms. PMID:27811975

Urea-assisted liquid-phase exfoliation of natural graphite into few-layer graphene

NASA Astrophysics Data System (ADS)

Hou, Dandan; Liu, Qinfu; Wang, Xianshuai; Qiao, Zhichuan; Wu, Yingke; Xu, Bohui; Ding, Shuli

2018-05-01

The mass production of graphene with high quality is desirable for its wide applications. Here, we demonstrated a facile method to exfoliate natural graphite into graphene in organic solvent by assisting of urea. The exfoliation of graphite may originate from the "molecular wedge" effect of urea, which can intercalate into the edge of natural graphite, thus facilitating the production of graphene dispersion with a high concentration up to 1.2 mg/mL. The obtained graphene is non-oxidized with negligible defects. Therefore, this approach has great promise in bulk production of graphene with superior quality for a variety of applications.

Determination of the Tribological Fundamentals of Solid Lubricated Ceramics. Volume 1. Summary

DTIC Science & Technology

1990-11-01

the length of the C-axis), leading to increased critical resolved shear stress/surface shear strength of the polycrystalline graphite and...weaker nature of the graphitic regions. Wear rates of pure, polycrystalline diamond range from -4 x 10- 16 m 3/N • m in vacuum to I x 10ൗ m3/N• m...Intercalated Graphite Molds. Triboflats hand-cut, oc-SiC paper- san !ed and fine diamond paper-polished from NiCI2/ HOPG and CdCl2/ HOPG (to remove the outer 0.5

NMR Spectra of Oriented Samples of Intercalated Fluorographite and 19F Chemical Shielding Anisotropy of the CIF 3 Molecule

NASA Astrophysics Data System (ADS)

Panich, A. M.

The analysis of 19F NMR spectra of polycrystalline and partially oriented samples of fluorinated graphite (C 2F) n intercalated with chlorine trifluoride has been carried out. Molecular mobility results in almost complete averaging of the dipole-dipole interactions of nuclei, while the essential chemical shielding anisotropy (CSA) is manifested. There is suggested molecular rotation about its C2 axes, which in turn rotates about the normal to the graphite plane. The CSA (σ || - σ ⊥) is determined to be 510 and -640 ppm, respectively, for the two inequivalent fluorine atoms of the molecule. The effect of the "antiparamagnetic" shielding leading to inversion of the chemical shielding tenser [(σ || - σ ⊥) < 0] for the equatorial F atom and anomalous line disposition in the NMR spectrum is discussed.

Formation of intercalation compound of kaolinite-glycine via displacing guest water by glycine.

PubMed

Zheng, Wan; Zhou, Jing; Zhang, Zhenqian; Chen, Likun; Zhang, Zhongfei; Li, Yong; Ma, Ning; Du, Piyi

2014-10-15

The kaolinite-glycine intercalation compound was successfully formed by displacing intercalated guest water molecules in kaolinite hydrate as a precursor. The microstructure of the compound was characterized by X-ray diffraction, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscope. Results show that glycine can only be intercalated into hydrated kaolinite to form glycine-kaolinite by utilizing water molecules as a transition phase. The intercalated glycine molecules were squeezed partially into the ditrigonal holes in the silicate layer, resulting in the interlayer distance of kaolinite reaching 1.03nm. The proper intercalation temperature range was between 20°C and 80°C. An intercalation time of 24h or above was necessary to ensure the complete formation of kaolinite-glycine. The highest intercalation degree of about 84% appeared when the system was reacted at the temperature of 80°C for 48h. There were two activation energies for the intercalation of glycine into kaolinite, one being 21kJ/mol within the temperature range of 20-65°C and the other 5.8kJ/mol between 65°C and 80°C. The intercalation degree (N) and intercalation velocity (v) of as a function of intercalation time (t) can be empirically expressed as N=-79.35e(-)(t)(/14.8)+80.1 and v=5.37e(-)(t)(/14.8), respectively. Copyright © 2014 Elsevier Inc. All rights reserved.

The Use of Pristine and Intercalated Graphite Fiber Composites as Buss Bars in Lead-Acid Batteries

NASA Technical Reports Server (NTRS)

Opaluch, Amanda M.

2004-01-01

This study was conducted as a part of the Firefly Energy Space Act Agreement project to investigate the possible use of composite materials in lead acid batteries. Specifically, it examined the use of intercalated graphite composites as buss bars. Currently, buss bars of these batteries are made of lead, a material that is problematic for several reasons. Over time, the lead is subject to both corrosion at the positive plate and sulfation at the negative plate, resulting in decreased battery life. In addition, the weight and size of the lead buss bars make for a heavy and cumbersome battery that is undesirable. Functionality and practicality of lead buss bars is adequate at best; consequently, investigation of more efficient composite materials would be advantageous. Practically speaking, graphite composites have a low density that is nearly one fourth that of its lead counterpart. A battery made of less dense materials would be more attractive to the consumer and the producer because it would be light and convenient. More importantly, low weight would be especially beneficial because it would result in greater overall power density of the battery. In addition to power density, use of graphite composite materials can also increase the life of the battery. From a functional standpoint, corrosion and sulfation at the positive and negative plates are major obstacles when considering how to extend battery life. Neither of these reactions are a factor when graphite composites replace lead parts because graphite is chemically non-reactive with the electrolyte within the battery. Without the problem of corrosion or sulfation, battery life expectancy can be almost doubled. The replacement of lead battery parts with composite materials is also more environmentally favorable because of easy disposal of organic materials. For this study, both pristine and bromine intercalated single-ply graphite fiber composites were created. The composites were fabricated in such a way as to facilitate their use in a 3" x 1/2" buss bar test cell. The prime objective of this investigation was to examine the effectiveness of a variety of graphite composite materials to act as buss bars and carry the current to and from the positive and negative battery plates. This energy transfer can be maximized by use of materials with high conductivity to minimize the buss resistance. Electrical conductivity of composites was measured using both a contactless eddy current probe and a four point measurement. In addition, the stability of these materials at battery-use conditions was characterized.

Synthesis of Copper Oxide/Graphite Composite for High-Performance Rechargeable Battery Anode.

PubMed

Cho, Sanghun; Ahn, Yong-Keon; Yin, Zhenxing; You, Duck-Jae; Kim, Hyunjin; Piao, Yuanzhe; Yoo, Jeeyoung; Kim, Youn Sang

2017-08-25

A novel copper oxide/graphite composite (GCuO) anode with high capacity and long cycle stability is proposed. A simple, one-step synthesis method is used to prepare the GCuO, through heat treatment of the Cu ion complex and pristine graphite. The gases generated during thermal decomposition of the Cu ion complex (H 2 and CO 2 ) induce interlayer expansion of the graphite planes, which assists effective ion intercalation. Copper oxide is formed simultaneously as a high-capacity anode material through thermal reduction of the Cu ion complex. Material analyses reveal the formation of Cu oxide nanoparticles and the expansion of the gaps between the graphite layers from 0.34 to 0.40 nm, which is enough to alleviate layer stress for reversible ion intercalation for Li or Na batteries. The GCuO cell exhibits excellent Li-ion battery half-cell performance, with a capacity of 532 mAh g -1 at 0.2 C (C-rate) and capacity retention of 83 % after 250 cycles. Moreover, the LiFePO 4 /GCuO full cell is fabricated to verify the high performance of GCuO in practical applications. This cell has a capacity of 70 mAh g -1 and a coulombic efficiency of 99 %. The GCuO composite is therefore a promising candidate for use as an anode material in advanced Li- or Na-ion batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Breathing of Graphite Particles in a Lithium-Ion Battery

NASA Astrophysics Data System (ADS)

Takata, Keiji; Okuda, Mitsuhiro; Yura, Nobuki; Tamura, Ryota

2012-04-01

We imaged changes in volume of graphite particles in a Li-ion battery due to the insertion and extraction of Li ions using scanning probe microscopy. When Li ions were extracted from the graphite particles, the particles were contracted, while expansion was induced in the interspaces between the particles. Variations of the images of volume changes depending on modulation frequencies clearly showed lithium intercalation. A linear relationship between the amplitudes of volume changes and the products of the diffusion elements and the reciprocals of the frequencies has been proven. Thus, the detected signals quantitatively well corresponded to the lithium ion movements.

Co-solvents with high coulombic efficiency in propylene carbonate based electrolytes

DOEpatents

Liu, Gao; Zhao, Hui; Park, Sang-Jae

2017-06-27

A homologous series of cyclic carbonate or propylene carbonate (PC) analogue solvents with increasing length of linear alkyl substitutes were synthesized and used as co-solvents with PC for graphite based lithium ion half cells. A graphite anode reaches a capacity around 310 mAh/g in PC and its analogue co-solvents with 99.95% Coulombic efficiency. Cyclic carbonate co-solvents with longer alkyl chains are able to prevent exfoliation of graphite when used as co-solvents with PC. The cyclic carbonate co-solvents of PC compete for solvation of Li ion with PC solvent, delaying PC co-intercalation. Reduction products of PC on graphite surfaces via single-electron path form a stable Solid Electrolyte Interphase (SEI), which allows the reversible cycling of graphite.

A sodium-ion battery exploiting layered oxide cathode, graphite anode and glyme-based electrolyte

NASA Astrophysics Data System (ADS)

Hasa, Ivana; Dou, Xinwei; Buchholz, Daniel; Shao-Horn, Yang; Hassoun, Jusef; Passerini, Stefano; Scrosati, Bruno

2016-04-01

Room-temperature rechargeable sodium-ion batteries (SIBs), in view of the large availability and low cost of sodium raw materials, represent an important class of electrochemical systems suitable for application in large-scale energy storage. In this work, we report a novel, high power SIB formed by coupling the layered P2-Na0.7CoO2 cathode with the graphite anode in an optimized ether-based electrolyte. The study firstly addresses the electrochemical optimization of the two electrode materials and then the realization and characterization of the novel SIB based on their combination. The cell represents an original sodium rocking chair battery obtained combining the intercalation/de-intercalation processes of sodium within the cathode and anode layers. We show herein that this battery, favored by suitable electrode/electrolyte combination, offers unique performance in terms of cycle life, efficiency and, especially, power capability.

Microwave exfoliated graphene oxide/TiO{sub 2} nanowire hybrid for high performance lithium ion battery

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

Ishtiaque Shuvo, Mohammad Arif; Rodriguez, Gerardo; Karim, Hasanul

Lithium ion battery (LIB) is a key solution to the demand of ever-improving, high energy density, clean-alternative energy systems. In LIB, graphite is the most commonly used anode material; however, lithium-ion intercalation in graphite is limited, hindering the battery charge rate and capacity. To date, one of the approaches in LIB performance improvement is by using porous carbon (PC) to replace graphite as anode material. PC's pore structure facilitates ion transport and has been proven to be an excellent anode material candidate in high power density LIBs. In addition, to overcome the limited lithium-ion intercalation obstacle, nanostructured anode assembly hasmore » been extensively studied to increase the lithium-ion diffusion rate. Among these approaches, high specific surface area metal oxide nanowires connecting nanostructured carbon materials accumulation have shown promising results for enhanced lithium-ion intercalation. Herein, we demonstrate a hydrothermal approach of growing TiO{sub 2} nanowires (TON) on microwave exfoliated graphene oxide (MEGO) to further improve LIB performance over PC. This MEGO-TON hybrid not only uses the high surface area of MEGO but also increases the specific surface area for electrode–electrolyte interaction. Therefore, this new nanowire/MEGO hybrid anode material enhances both the specific capacity and charge–discharge rate. Scanning electron microscopy and X-ray diffraction were used for materials characterization. Battery analyzer was used for measuring the electrical performance of the battery. The testing results have shown that MEGO-TON hybrid provides up to 80% increment of specific capacity compared to PC anode.« less

Release behavior and toxicity profiles towards A549 cell lines of ciprofloxacin from its layered zinc hydroxide intercalation compound.

PubMed

Abdul Latip, Ahmad Faiz; Hussein, Mohd Zobir; Stanslas, Johnson; Wong, Charng Choon; Adnan, Rohana

2013-01-01

Layered hydroxides salts (LHS), a layered inorganic compound is gaining attention in a wide range of applications, particularly due to its unique anion exchange properties. In this work, layered zinc hydroxide nitrate (LZH), a family member of LHS was intercalated with anionic ciprofloxacin (CFX), a broad spectrum antibiotic via ion exchange in a mixture solution of water:ethanol. Powder x-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) confirmed the drug anions were successfully intercalated in the interlayer space of LZH. Specific surface area of the obtained compound was increased compared to that of the host due to the different pore textures between the two materials. CFX anions were slowly released over 80 hours in phosphate-buffered saline (PBS) solution due to strong interactions that occurred between the intercalated anions and the host lattices. The intercalation compound demonstrated enhanced antiproliferative effects towards A549 cancer cells compared to the toxicity of CFX alone. Strong host-guest interactions between the LZH lattice and the CFX anion give rise to a new intercalation compound that demonstrates sustained release mode and enhanced toxicity effects towards A549 cell lines. These findings should serve as foundations towards further developments of the brucite-like host material in drug delivery systems.

Controlling the actuation properties of MXene paper electrodes upon cation intercalation

DOE PAGES

Come, Jeremy E.; Black, Jennifer M.; Naguib, Michael; ...

2015-08-05

Atomic force microscopy was used to monitor the macroscopic deformation in a delaminated Ti₃C₂ paper electrode in-situ, during charge/discharge in a variety of aqueous electrolytes to examine the effect of the cation intercalation on the electrochemical behavior and mechanical response. The results show a strong dependence of the electrode deformation on cation size and charge. The electrode undergoes a large contraction during Li⁺, Na⁺ or Mg²⁺ intercalation, differentiating the Ti₃C₂ paper from conventional electrodes where redox intercalation of ions (e.g. Li⁺) into the bulk phase (e.g. graphite, silicon) results in volumetric expansion. This feature may explain the excellent rate performancemore » and cyclability reported for MXenes. We also demonstrated that the variation of the electromechanical contraction can be easily adjusted by electrolyte exchange, and shows interesting characteristics for the design of actuators based on 2D metal carbides.« less

Nano-scaled graphene platelets with a high length-to-width aspect ratio

DOEpatents

Zhamu, Aruna; Guo, Jiusheng; Jang, Bor Z.

2010-09-07

This invention provides a nano-scaled graphene platelet (NGP) having a thickness no greater than 100 nm and a length-to-width ratio no less than 3 (preferably greater than 10). The NGP with a high length-to-width ratio can be prepared by using a method comprising (a) intercalating a carbon fiber or graphite fiber with an intercalate to form an intercalated fiber; (b) exfoliating the intercalated fiber to obtain an exfoliated fiber comprising graphene sheets or flakes; and (c) separating the graphene sheets or flakes to obtain nano-scaled graphene platelets. The invention also provides a nanocomposite material comprising an NGP with a high length-to-width ratio. Such a nanocomposite can become electrically conductive with a small weight fraction of NGPs. Conductive composites are particularly useful for shielding of sensitive electronic equipment against electromagnetic interference (EMI) or radio frequency interference (RFI), and for electrostatic charge dissipation.

Influence of carbon additives on operational properties of the intumescent coatings for the fire protection of building constructions

NASA Astrophysics Data System (ADS)

Zybina, Olga; Gravit, Marina; Stein, Yelena

2017-10-01

In work ability of the intercalated graphite entered into the fireproof intumescent compositions to act as catalytically active additive raising operational characteristics of the classical distending coverings intended for fire protection of building constructions. It is established that thermal expanded graphite, as well as nano-additives, increase frequency rate, durability, elasticity, density and uniformity of a coke layer of a fireproof covering for increase of fire resistance of a building construction.

Radial Breathing Modes in Cosmochemistry and Meteoritics

NASA Technical Reports Server (NTRS)

Wilson, T.L.; Wilson, K.B.

2009-01-01

One area of continuing interest in cosmochemistry and meteoritics (C&M) is the identification of the nature of Q-phase, although some researchers in C&M are not reporting relevant portions of Raman spectral data. Q is the unidentified carrier of noble gases in carbonaceous chondrites (CCs). Being carbonaceous, the focus has been on any number of Q-candidates arising from the sp2 hybridization of carbon (C). These all derive from various forms of graphene, a monolayer of C atoms packed into a two-dimensional (2D) hexagonal honeycomb lattice that is the basic building block for graphitic materials of all other dimensions for sp2 allotropes of C. As a basic lattice, 2D graphene can be curled into fullerenes (0D), wrapped into carbon nanotubes or CNTs (1D), and stacked into graphite (3D). These take such additional forms as scroll-like carbon whiskers, carbon fibers, carbon onions, GPCs (graphite polyhedral crystals) [6], and GICs (graphite intercalation compounds). Although all of these have been observed in meteoritics, the issue is which can explain the Q-abundances. In brief, one or more of the 0D-3D sp2 hybridization forms of C is Q. For some Q-candidates, the radial breathing modes (RBMs) are the most important Raman active vibrational modes that exist, and bear a direct relevance to solving this puzzle. Typically in C&M they are ignored when present. Their importance is addressed here as smoking-gun signatures for certain Q-candidates and are very relevant to the ultimate identification of Q.

Release behavior and toxicity profiles towards A549 cell lines of ciprofloxacin from its layered zinc hydroxide intercalation compound

PubMed Central

2013-01-01

Background Layered hydroxides salts (LHS), a layered inorganic compound is gaining attention in a wide range of applications, particularly due to its unique anion exchange properties. In this work, layered zinc hydroxide nitrate (LZH), a family member of LHS was intercalated with anionic ciprofloxacin (CFX), a broad spectrum antibiotic via ion exchange in a mixture solution of water:ethanol. Results Powder x-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) confirmed the drug anions were successfully intercalated in the interlayer space of LZH. Specific surface area of the obtained compound was increased compared to that of the host due to the different pore textures between the two materials. CFX anions were slowly released over 80 hours in phosphate-buffered saline (PBS) solution due to strong interactions that occurred between the intercalated anions and the host lattices. The intercalation compound demonstrated enhanced antiproliferative effects towards A549 cancer cells compared to the toxicity of CFX alone. Conclusions Strong host-guest interactions between the LZH lattice and the CFX anion give rise to a new intercalation compound that demonstrates sustained release mode and enhanced toxicity effects towards A549 cell lines. These findings should serve as foundations towards further developments of the brucite-like host material in drug delivery systems. PMID:23849189

Layered Compounds and Intercalation Chemistry: An Example of Chemistry and Diffusion in Solids.

ERIC Educational Resources Information Center

Whittingham, M. Stanley; Chianelli, Russell R.

1980-01-01

Considers a few areas of oxide/sulfide and intercalation-type chemistry. Discusses synthesis of the disulfides of the metals of group IVB, VB, and VIB; the intercalation reaction between lithium and titanium disulfide; other intercalates; and sulfide catalysts. (CS)

Intercalated Graphite Fiber Conductor.

DTIC Science & Technology

1980-12-01

melting solders, used as electrical contacts as well as sealants for the glass containers described earlier, and high temperature gold varnish , used on...corrosion resistant to fluorine containing chemicals. Since the moisture permeability of the TFE is much less than that of the FEP, attempts were made to

Irreversible Capacities of Graphite in Low Temperature Electrolytes for Lithium-Ion Batteries

NASA Technical Reports Server (NTRS)

Ratnakumar, B.; Smart, M.; Surampudi, S.; Wang, Y.; Zhang, X.; Greenbaum, S.; Hightower, A.; Ahn, C.; Fultz, B.

1999-01-01

Carbonaceous anode materials in lithium ion rechargeable cells experience irreversible capacity, mainly due to a consumption of lithium in the formation of surface passive films. The stability and kinetics of lithium intercalation into the carbon anodes are dictated by these films.

Intercalation chemistry of zirconium 4-sulfophenylphosphonate

NASA Astrophysics Data System (ADS)

Svoboda, Jan; Zima, Vítězslav; Melánová, Klára; Beneš, Ludvík; Trchová, Miroslava

2013-12-01

Zirconium 4-sulfophenylphosphonate is a layered material which can be employed as a host for the intercalation reactions with basic molecules. A wide range of organic compounds were chosen to represent intercalation ability of zirconium 4-sulfophenylphosphonate. These were a series of alkylamines from methylamine to dodecylamine, 1,4-phenylenediamine, p-toluidine, 1,8-diaminonaphthalene, 1-aminopyrene, imidazole, pyridine, 4,4‧-bipyridine, poly(ethylene imine), and a series of amino acids from glycine to 6-aminocaproic acid. The prepared compounds were characterized by powder X-ray diffraction, thermogravimetry analysis and IR spectroscopy and probable arrangement of the guest molecules in the interlayer space of the host is proposed based on the interlayer distance of the prepared intercalates and amount of the intercalated guest molecules.

Hazards, Safety and Design Considerations for Commercial Lithium-ion Cells and Batteries

NASA Technical Reports Server (NTRS)

Jeevarajan, Judith

2007-01-01

This viewgraph presentation reviews the features of the Lithium-ion batteries, particularly in reference to the hazards and safety of the battery. Some of the characteristics of the Lithium-ion cell are: Highest Energy Density of Rechargeable Battery Chemistries, No metallic lithium, Leading edge technology, Contains flammable electrolyte, Charge cut-off voltage is critical (overcharge can result in fire), Open circuit voltage higher than metallic lithium anode types with similar organic electrolytes. Intercalation is a process that places small ions in crystal lattice. Small ions (such as lithium, sodium, and the other alkali metals) can fit in the interstitial spaces in a graphite lattice. These metallic ions can go farther and force the graphitic planes apart to fit two, three, or more layers of metallic ions between the carbon sheets. Other features of the battery/cell are: The graphite is conductive, Very high energy density compared to NiMH or NiCd, Corrosion of aluminum occurs very quickly in the presence of air and electrolyte due to the formation of HF from LiPF6 and HF is highly corrosive. Slides showing the Intercalation/Deintercalation and the chemical reactions are shown along with the typical charge/discharge for a cylindrical cell. There are several graphs that review the hazards of the cells.

Hydrogen Storage in metal-modified single-walled carbon nanotubes

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

Dr. Ahn

2004-04-30

It has been known for over thirty years that potassium-intercalated graphites can readily adsorb and desorb hydrogen at {approx}1 wt% at 77 K. These levels are much higher than can be attained in pure graphite, owing to a larger thermodynamic enthalpy of adsorption. This increased enthalpy may allow hydrogen sorption at higher temperatures. Potassium has other beneficial effects that enable the design of a new material: (a) Increased adsorption enthalpy in potassium-intercalated graphite compared to pure graphite reduces the pressure and increases the temperature required for a given fractional coverage of hydrogen adsorption. We expect the same effects in potassium-intercalatedmore » SWNTs. (b) As an intercalant, potassium separates c-axis planes in graphite. Potassium also separates the individual tubes of SWNTs ropes producing swelling and increased surface area. Increased surface area provides more adsorption sites, giving a proportionately higher capacity. The temperature of adsorption depends on the enthalpy of adsorption. The characteristic temperature is roughly the adsorption enthalpy divided by Boltzmann's constant, k{sub B}. For the high hydrogen storage capacity of SWNTs to be achieved at room temperature, it is necessary to increase the enthalpy of adsorption. Our goal for this project was to use metal modifications to the carbon surface of SWNTs in order to address both enhanced adsorption and surface area. For instance, the enthalpy of sorption of hydrogen on KC8 is 450 meV/H{sub 2}, whereas it is 38 meV/H{sub 2} for unmodified SWNTs. By adsorption thermodynamics we expect approximately that the same performance of SWNTs at 77 K will be achieved at a temperature of [450/38] 77 K = 900 K. This is a high temperature, so we expect that adsorption on nearly all the available sites for hydrogen will occur at room temperature under a much lower pressure. This pressure can be estimated conveniently, since the chemical potential of hydrogen is approximately proportional to the logarithm of the pressure. Using 300 K for room temperature, the 100 bar pressure requirement is reduced to exp(-900/300) 100 bar = 5 bar at room temperature. This is in the pressure range used for prior experimental work such as that of Colin and Herold in the late 1960's and early 1970's.« less

Effect of length of chopped pristine and intercalated graphite fibers on the resistivity of fiber networks

NASA Technical Reports Server (NTRS)

Gaier, James R.; Stahl, Mark

1988-01-01

Samples of Amoco P-100 fibers were chopped to lengths of 3.14, 2.53, 1.90, 1.27, 0.66 mm, or milled for 2 hours. The two-point resistivity of compacts of these fibers were measured as a function of pressure from 34 kPa to 143 MPa. Samples of each fiber length were intercalated with bromine at room temperature and similarly measured. The low pressure resistivity of the compacts decreased with increasing fiber length. Intercalation lowered the resistivity of each of the chopped length compacts, but raised the resistivity of the milled fiber compacts. Bulk resistivity of all samples decreased with increasing pressure at similar rates. Even though fiber volumes were as low as 5 percent, all measurements exhibited measurable resistivity. A greater change with pressure in the resistance was observed for shorter fibers than for longer, probably an indication of tighter fiber packing. Intercalation appeared to have no effect on the fiber to fiber contact resistance.

Redox-controlled potassium intercalation into two polyaromatic hydrocarbon solids

NASA Astrophysics Data System (ADS)

Romero, F. Denis; Pitcher, M. J.; Hiley, C. I.; Whitehead, G. F. S.; Kar, S.; Ganin, A. Y.; Antypov, D.; Collins, C.; Dyer, M. S.; Klupp, G.; Colman, R. H.; Prassides, K.; Rosseinsky, M. J.

2017-07-01

Alkali metal intercalation into polyaromatic hydrocarbons (PAHs) has been studied intensely after reports of superconductivity in a number of potassium- and rubidium-intercalated materials. There are, however, no reported crystal structures to inform our understanding of the chemistry and physics because of the complex reactivity of PAHs with strong reducing agents at high temperature. Here we present the synthesis of crystalline K2Pentacene and K2Picene by a solid-solid insertion protocol that uses potassium hydride as a redox-controlled reducing agent to access the PAH dianions, and so enables the determination of their crystal structures. In both cases, the inserted cations expand the parent herringbone packings by reorienting the molecular anions to create multiple potassium sites within initially dense molecular layers, and thus interact with the PAH anion π systems. The synthetic and crystal chemistry of alkali metal intercalation into PAHs differs from that into fullerenes and graphite, in which the cation sites are pre-defined by the host structure.

Characterization of Intercalated Graphite Fibers for Microelectromechanical Systems (MEMS) Applications

DTIC Science & Technology

2007-03-01

electric charge to drive movement, eg. a micromirror . These two actuator types have different characteristics and apply dif- ferent forces. The thermal...actuators include micromirrors , comb drives, cantilevers and scratch drives. A scratch drive actuator uses an applied square wave voltage to operate, as

Correlation of intercalation potential with d-electron configurations for cathode compounds of lithium-ion batteries.

PubMed

Chen, Zhenlian; Zhang, Caixia; Zhang, Zhiyong; Li, Jun

2014-07-14

The d-electron localization is widely recognized as important to transport properties of transition metal compounds, but its role in the energy conversion of intercalation reactions of cathode compounds is still not fully explored. In this work, the correlation of intercalation potential with electron affinity, a key energy term controlling electron intercalation, then with d-electron configuration, is investigated. Firstly, we find that the change of the intercalation potential with respect to the transition metal cations within the same structure class is correlated in an approximately mirror relationship with the electron affinity, based on first-principles calculations on three typical categories of cathode compounds including layered oxides and polyoxyanions Then, by using a new model Hamiltonian based on the crystal-field theory, we reveal that the evolution is governed by the combination of the crystal-field splitting and the on-site d-d exchange interactions. Further, we show that the charge order in solid-solution composites and the compatibility of multi-electron redox steps could be inferred from the energy terms with the d-electron configuration alternations. These findings may be applied to rationally designing new chemistry for the lithium-ion batteries and other metal-ion batteries.

Immobilization of kojic acid in ZnAl-hydrotalcite like compounds

NASA Astrophysics Data System (ADS)

Ambrogi, Valeria; Perioli, Luana; Nocchetti, Morena; Latterini, Loredana; Pagano, Cinzia; Massetti, Elena; Rossi, Carlo

2012-01-01

Kojic acid (KOJ) is a melanin synthesis inhibitor widely used as skin lightening agent in topical preparations. Unfortunately it is easily susceptible to photo-oxidation, phenomenon responsible for chemical and organoleptic modifications. The aim of this work was the intercalation of KOJ in hydrotalcite-like compounds (HTlc) in order to stabilize KOJ and to reduce its photolability. Hydrotalcite containing Zn and Al (ZnAl-HTlc) was used as host to obtain the final compound ZnAl-HTlc-KOJ. The intercalation was carried out, after many attempts, by ionic exchange mechanism by means of the strong base EtO- in anhydrous ethanol/dimethylsulfoxide (DMSO) mixture as solvent in order to generate KOJ- anions. The final product was characterized by the X-ray powder diffraction (XRPD), FT-IR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis. The intercalated compound was formulated in a siliconic water free self-emulsifying ointment and the in vitro release profile was evaluated. All samples (intercalation compound and its formulation) were submitted also to spectrophotometric assays in order to evaluate the matrix protective effect towards ultraviolet rays.

From Rome to Como: 20 years of active research on carbon-based electrodes for lithium batteries at INP-Grenoble

NASA Astrophysics Data System (ADS)

Yazami, Rachid

This paper reviews the main areas of research performed at different Laboratories of the Institut National Polytechnique de Grenoble (INPG) over the past 20 years, specifically on cabonaceous materials for electrode applications in lithium batteries. The most significant event was the discovery in the early 1980s of reversible lithium intercalation into graphite in polymer electrolytes, which led to the use of this material in today's lithium-ion batteries. Important work was also carried out on positive electrode for primary and secondary batteries, especially graphite oxide and graphite fluoride. Most of these results were presented at the 10 IMLB series Symposia, which started in Rome in 1982 and were back to Como, Italy, in 2000.

Degradation Mechanisms of Electrochemically Cycled Graphite Anodes in Lithium-ion Cells

NASA Astrophysics Data System (ADS)

Bhattacharya, Sandeep

This research is aimed at developing advanced characterization methods for studying the surface and subsurface damage in Li-ion battery anodes made of polycrystalline graphite and identifying the degradation mechanisms that cause loss of electrochemical capacity. Understanding microstructural aspects of the graphite electrode degradation mechanisms during charging and discharging of Li-ion batteries is of key importance in order to design durable anodes with high capacity. An in-situ system was constructed using an electrochemical cell with an observation window, a large depth-of-field digital microscope and a micro-Raman spectrometer. It was revealed that electrode damage by removal of the surface graphite fragments of 5-10 mum size is the most intense during the first cycle that led to a drastic capacity drop. Once a solid electrolyte interphase (SEI) layer covered the electrode surface, the rate of graphite particle loss decreased. Yet, a gradual loss of capacity continued by the formation of interlayer cracks adjacent to SEI/graphite interfaces. Deposition of co-intercalation compounds, LiC6, Li2CO3 and Li2O, near the crack tips caused partial closure of propagating graphite cracks during cycling and reduced the crack growth rate. Bridging of crack faces by delaminated graphite layers also retarded crack propagation. The microstructure of the SEI layer, formed by electrochemical reduction of the ethylene carbonate based electrolyte, consisted of ˜5-20 nm sized crystalline domains (containing Li2CO3, Li2O 2 and nano-sized graphite fragments) dispersed in an amorphous matrix. During the SEI formation, two regimes of Li-ion diffusion were identified at the electrode/electrolyte interface depending on the applied voltage scan rate (dV/dt). A low Li-ion diffusion coefficient ( DLi+) at dV/dt < 0.05 mVs-1 produced a tubular SEI that uniformly covered the graphite surface and prevented damage at 25°C. At 60°C, a high D Li+ formed a Li2CO3-enriched SEI and ensued a 28% increase in the battery capacity at 25°C. On correlating the microscopic information to the electrochemical performance, novel Li2CO3-coated electrodes were fabricated that were durable. The SEI formed on pre-treated electrodes reduced the strain in the graphite lattice from 0.4% (for uncoated electrodes) to 0.1%, facilitated Li-ion diffusion and hence improved the capacity retention of Li-ion batteries during long-term cycling.

Preparation and Characterization of Novel Montmorillonite Nanocomposites

NASA Astrophysics Data System (ADS)

Mansa, Rola

Clay minerals have historically played a consequential role in human health. While the beginnings were rooted in geophagy, a primitive act of consuming earth, the health-related uses of clay minerals have evolved and diversified over time.. As excipients in pharmaceutical formulations, clay minerals can attribute novel properties onto intercalated compounds. Intercalating oxybenzone, a UV filter, within the interlamellar space of montmorillonite is desirable in order to minimize direct contact with skin. Intercalating resveratrol, a compound known for attributing beneficial effects onto human health, may be advantageous since this compound is susceptible to cis-trans isomerisation. The strategy of using alkylammonium--modified clay was undertaken and proved successful for the intercalation of oxybenzone. The field of biopolymer/layered silicate nanocomposites is heavily researched for use in a multitude of applications. Novel montmorillonite nanocomposites were prepared with neutral guar gum and cationic guar gum, using an environmentally friendly process and are fully characterized.

Electrochemistry and safety of Li 4Ti 5O 12 and graphite anodes paired with LiMn 2O 4 for hybrid electric vehicle Li-ion battery applications

NASA Astrophysics Data System (ADS)

Belharouak, Ilias; Koenig, Gary M.; Amine, K.

A promising anode material for hybrid electric vehicles (HEVs) is Li 4Ti 5O 12 (LTO). LTO intercalates lithium at a voltage of ∼1.5 V relative to lithium metal, and thus this material has a lower energy compared to a graphite anode for a given cathode material. However, LTO has promising safety and cycle life characteristics relative to graphite anodes. Herein, we describe electrochemical and safety characterizations of LTO and graphite anodes paired with LiMn 2O 4 cathodes in pouch cells. The LTO anode outperformed graphite with regards to capacity retention on extended cycling, pulsing impedance, and calendar life and was found to be more stable to thermal abuse from analysis of gases generated at elevated temperatures and calorimetric data. The safety, calendar life, and pulsing performance of LTO make it an attractive alternative to graphite for high power automotive applications, in particular when paired with LiMn 2O 4 cathode materials.

Fabrication of Iron-Containing Carbon Materials From Graphite Fluoride

NASA Technical Reports Server (NTRS)

Hung, Ching-cheh

1996-01-01

Carbon materials containing iron alloy, iron metal, iron oxide or iron halide were fabricated. Typical samples of these metals were estimated to contain 1 iron atom per 3.5 to 5 carbon atoms. Those carbon materials containing iron alloy, iron metal, and/or Fe3O4 were magnetic. The kinetics of the fabrication process were studied by exposing graphite fluoride (CF(0.68)) to FeCl3 over a 280 to 420 C temperature range. Between 280 and 295 C, FeCl3 quickly entered the structure of CF(0.68), broke the carbon-fluorine bonds, and within 10 to 30 min, completely converted it to carbon made up of graphite planes between which particles of crystalline FeF3 and noncrystalline FeCl3 were located. Longer reaction times (e.g., 28 hr) or higher reaction temperatures (e.g., 420 C) produced materials containing graphite, a FeCl3-graphite intercalation compound, FeCl2(center dot)4H2O, and FeCl2(center dot)2H2O. These products were further heat treated to produce iron-containing carbon materials. When the heating temperature was kept in the 750 to 850 C range, and the oxygen supply was kept at the optimum level, the iron halides in the carbon structure were converted to iron oxides. Raising the heat to temperatures higher than 900 C reduced such iron oxides to iron metal. The kinetics of these reactions were used to suggest processes for fabricating carbon materials containing iron alloy. Such processes were then tested experimentally. In one of the successful trial runs, commercially purchased CF(0.7) powder was used as the reactant, and NiO was added during the final heating to 1200 C as a source of both nickel and oxygen. The product thus obtained was magnetic and was confirmed to be a nickel-iron alloy in carbon.

Rechargeable LiNiO2/carbon cells

NASA Astrophysics Data System (ADS)

Dahn, J. R.; von Sacken, U.; Juzkow, M. W.; Al-Janaby, H.

1991-08-01

Rechargeable cells can be made using two different intercalation compounds, in which the chemical potential of the intercalant differs by several eV, for the electrodes. The factors that play a role in the selection of appropriate lithium intercalation compounds for such cells are discussed. For the ease of cell assembly, the cathode should be stable in air when it is fully intercalated, like LiNiO2. For the anode, the chemical potential of the intercalated Li should be close to that of Li metal, like it is in Li(x)C6. The intercalation of Li in LiNiO2 is discussed, and then in petroleum coke. Then, it is shown that LiNiO2/coke cells have high energy density, long cycle life, excellent high-temperature performance, low self-discharge rates, can be repeatedly discharged to zero volts without damage, and are easily fabricated. It is considered that this type of cell shows far more promise for widespread applications than traditional secondary Li cells using metallic Li anodes.

Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition

PubMed Central

Nakayama, Hirokazu; Hayashi, Aki

2014-01-01

The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids. PMID:25080007

Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition.

PubMed

Nakayama, Hirokazu; Hayashi, Aki

2014-07-30

The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids.

A comparison of the bromination dynamics of pitch-based and vapor-grown graphite fibers

NASA Technical Reports Server (NTRS)

Gaier, J. R.

1986-01-01

The electrical resistance of pitch based P-100 fibers and experimental organic vapor grown fibers was recorded in-situ during bromination and subsequent exposure to ambient laboratory air. The results indicate that the bromination and debromination reactions proceed much slower for vapor grown fibers than for pitch based. While this may be due in part to the larger diameter of the vapor grown fibers, the majority of the effect can probably be attributed to the differences in graphene plane orientation between the fiber types. Although the reactions are slower in the vapor grown than in the pitch based fibers, the extent of reaction as measured by the change in electrical resistance is essentially the same, with comparable (or larger) decreases in resistivity. The bromination reaction proceeds with one or more plateaus in the resistance versus time curves, which suggests staging and strengthens the argument that these fibers produce true intercalation compounds.

Reversible calcium alloying enables a practical room-temperature rechargeable calcium-ion battery with a high discharge voltage

NASA Astrophysics Data System (ADS)

Wang, Meng; Jiang, Chunlei; Zhang, Songquan; Song, Xiaohe; Tang, Yongbing; Cheng, Hui-Ming

2018-06-01

Calcium-ion batteries (CIBs) are attractive candidates for energy storage because Ca2+ has low polarization and a reduction potential (-2.87 V versus standard hydrogen electrode, SHE) close to that of Li+ (-3.04 V versus SHE), promising a wide voltage window for a full battery. However, their development is limited by difficulties such as the lack of proper cathode/anode materials for reversible Ca2+ intercalation/de-intercalation, low working voltages (<2 V), low cycling stability, and especially poor room-temperature performance. Here, we report a CIB that can work stably at room temperature in a new cell configuration using graphite as the cathode and tin foils as the anode as well as the current collector. This CIB operates on a highly reversible electrochemical reaction that combines hexafluorophosphate intercalation/de-intercalation at the cathode and a Ca-involved alloying/de-alloying reaction at the anode. An optimized CIB exhibits a working voltage of up to 4.45 V with capacity retention of 95% after 350 cycles.

Intercalation compounds and electrodes for batteries

DOEpatents

Chiang, Yet-Ming; Sadoway, Donald R.; Jang, Young-Il; Huang, Biyan

2004-09-07

This invention concerns intercalation compounds and in particular lithium intercalation compounds which have improved properties for use in batteries. Compositions of the invention include particulate metal oxide material having particles of multicomponent metal oxide, each including an oxide core of at least first and second metals in a first ratio, and each including a surface coating of metal oxide or hydroxide that does not include the first and second metals in the first ratio formed by segregation of at least one of the first and second metals from the core. The core may preferably comprise Li.sub.x M.sub.y N.sub.z O.sub.2 wherein M and N are metal atom or main group elements, x, y and z are numbers from about 0 to about 1 and y and z are such that a formal charge on M.sub.y N.sub.z portion of the compound is (4-x), and having a charging voltage of at least about 2.5V. The invention may also be characterized as a multicomponent oxide microstructure usable as a lithium intercalation material including a multiphase oxide core and a surface layer of one material, which is a component of the multiphase oxide core, that protects the underlying intercalation material from chemical dissolution or reaction. In a particular preferred example the multicomponent oxide may be an aluminum-doped lithium manganese oxide composition. Such aluminum-doped lithium manganese oxide compositions, having an orthorhombic structure, also form a part of the invention. In addition, the invention includes articles, particularly electrodes, for batteries formed from the compositions of the invention, and batteries including such electrodes. The invention further relates to a composite intercalation material comprising at least two compounds in which at least one compound has an orthorhombic structure Li.sub.x Al.sub.y Mn.sub.1-y O.sub.2, where y is nonzero, or a mixture of orthorhombic and monoclinic Li.sub.x Al.sub.y Mn.sub.1-y O.sub.2.

An ultrafast rechargeable aluminium-ion battery.

PubMed

Lin, Meng-Chang; Gong, Ming; Lu, Bingan; Wu, Yingpeng; Wang, Di-Yan; Guan, Mingyun; Angell, Michael; Chen, Changxin; Yang, Jiang; Hwang, Bing-Joe; Dai, Hongjie

2015-04-16

The development of new rechargeable battery systems could fuel various energy applications, from personal electronics to grid storage. Rechargeable aluminium-based batteries offer the possibilities of low cost and low flammability, together with three-electron-redox properties leading to high capacity. However, research efforts over the past 30 years have encountered numerous problems, such as cathode material disintegration, low cell discharge voltage (about 0.55 volts; ref. 5), capacitive behaviour without discharge voltage plateaus (1.1-0.2 volts or 1.8-0.8 volts) and insufficient cycle life (less than 100 cycles) with rapid capacity decay (by 26-85 per cent over 100 cycles). Here we present a rechargeable aluminium battery with high-rate capability that uses an aluminium metal anode and a three-dimensional graphitic-foam cathode. The battery operates through the electrochemical deposition and dissolution of aluminium at the anode, and intercalation/de-intercalation of chloroaluminate anions in the graphite, using a non-flammable ionic liquid electrolyte. The cell exhibits well-defined discharge voltage plateaus near 2 volts, a specific capacity of about 70 mA h g(-1) and a Coulombic efficiency of approximately 98 per cent. The cathode was found to enable fast anion diffusion and intercalation, affording charging times of around one minute with a current density of ~4,000 mA g(-1) (equivalent to ~3,000 W kg(-1)), and to withstand more than 7,500 cycles without capacity decay.

Comparative analysis of topoisomerase IB inhibition and DNA intercalation by flavonoids and similar compounds: structural determinates of activity

PubMed Central

2004-01-01

Flavonoids and other polyphenolic compounds have been shown to inhibit human topoisomerase IB (topo I) through both inhibition of relaxation activity and through stabilization of the cleavable complex (poisoning). Some flavonoids have also been shown to intercalate DNA, and an association of topoisomerase inhibition with intercalation has been noted. We surveyed 34 polyphenolic compounds, primarily flavonoid glycones and aglycones, for their ability to inhibit topo I and to intercalate DNA using an in vitro gel electrophoresis method. We show that the most potent topo I poisons are the flavones and flavonols, and that these generally, but not always, are found to be DNA intercalators. There was no clear correlation, however, of topo-I-poisoning activity with the degree of DNA unwinding. Surprisingly, both DNA intercalation and topo I poisoning were shown to occur with some flavone glycones, including the C-glycosylflavone orientin. Inhibition of relaxation activity by flavonoids was found to be difficult to quantify and was most likely to be due to non-specific inhibition through flavonoid aggregation. As part of a structure–activity analysis, we also investigated the acid–base chemistry of flavonoids and determined that many flavonoids show acid–base activity with a pKa in the physiological pH region. For this reason, subtle pH changes can have significant effects on solution activity of flavonoids and their concomitant biological activity. In addition, these effects may be complicated by pH-dependent aggregation and oxidative degradation. Finally, we develop a simple model for the intercalation of flavonoids into DNA and discuss possible consequences of intercalation and topoisomerase inhibition on a number of cellular processes. PMID:15312049

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

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

Mao, Chengyu; Wood, Marissa; David, Lamuel Abraham

Here, most lithium-ion batteries still rely on intercalation-type graphite materials for anodes, so it is important to consider their role in full cells for applications in electric vehicles. Here, we systematically evaluate the chemical and physical properties of six commercially-available natural and synthetic graphites to establish which factors have the greatest impact on the cycling stability of full cells with nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes. Electrochemical data and post-mortem characterization explain the origin of capacity fade. The NMC811 cathode shows large irreversible capacity loss and impedance growth, accounting for much of full cell degradation. However, six graphite anodes demonstrate significant differencesmore » with respect to structural change, surface area, impedance growth, and SEI chemistry, which impact overall capacity retention. We found long cycle life correlated most strongly with stable graphite crystallite size. In addition, graphites with lower surface area generally had higher coulombic efficiencies during formation cycles, which led to more stable long-term cycling. The best graphite screened here enables a capacity retention around 90% in full pouch cells over extensive long-term cycling compared to only 82% for cells with the lowest performing graphite. The results show that optimal graphite selection improves cycling stability of high energy lithium-ion cells.« less

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

DOE PAGES

Mao, Chengyu; Wood, Marissa; David, Lamuel Abraham; ...

2018-06-16

Here, most lithium-ion batteries still rely on intercalation-type graphite materials for anodes, so it is important to consider their role in full cells for applications in electric vehicles. Here, we systematically evaluate the chemical and physical properties of six commercially-available natural and synthetic graphites to establish which factors have the greatest impact on the cycling stability of full cells with nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes. Electrochemical data and post-mortem characterization explain the origin of capacity fade. The NMC811 cathode shows large irreversible capacity loss and impedance growth, accounting for much of full cell degradation. However, six graphite anodes demonstrate significant differencesmore » with respect to structural change, surface area, impedance growth, and SEI chemistry, which impact overall capacity retention. We found long cycle life correlated most strongly with stable graphite crystallite size. In addition, graphites with lower surface area generally had higher coulombic efficiencies during formation cycles, which led to more stable long-term cycling. The best graphite screened here enables a capacity retention around 90% in full pouch cells over extensive long-term cycling compared to only 82% for cells with the lowest performing graphite. The results show that optimal graphite selection improves cycling stability of high energy lithium-ion cells.« less

NANOWIRE CATHODE MATERIAL FOR LITHIUM-ION BATTERIES

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

John Olson, PhD

2004-07-21

This project involved the synthesis of nanowire ã-MnO2 and characterization as cathode material for high-power lithium-ion batteries for EV and HEV applications. The nanowire synthesis involved the edge site decoration nanowire synthesis developed by Dr. Reginald Penner at UC Irvine (a key collaborator in this project). Figure 1 is an SEM image showing ã-MnO2 nanowires electrodeposited on highly oriented pyrolytic graphite (HOPG) electrodes. This technique is unique to other nanowire template synthesis techniques in that it produces long (>500 um) nanowires which could reduce or eliminate the need for conductive additives due to intertwining of fibers. Nanowire cathode for lithium-ionmore » batteries with surface areas 100 times greater than conventional materials can enable higher power batteries for electric vehicles (EVs) and hybrid electric vehicles (HEVs). The synthesis of the ã-MnO2 nanowires was successfully achieved. However, it was not found possible to co-intercalate lithium directly in the nanowire synthesis. Based on input from proposal reviewers, the scope of the project was altered to attempt the conversion into spinel LiMn2O4 nanowire cathode material by solid state reaction of the ã-MnO2 nanowires with LiNO3 at elevated temperatures. Attempts to perform the conversion on the graphite template were unsuccessful due to degradation of the graphite apparently caused by oxidative attack by LiNO3. Emphasis then shifted to quantitative removal of the nanowires from the graphite, followed by the solid state reaction. Attempts to quantitatively remove the nanowires by several techniques were unsatisfactory due to co-removal of excess graphite or poor harvesting of nanowires. Intercalation of lithium into ã-MnO2 electrodeposited onto graphite was demonstrated, showing a partial demonstration of the ã-MnO2 material as a lithium-ion battery cathode material. Assuming the issues of nanowires removal can be solved, the technique does offer potential for creating high-power lithium-ion battery cathode needed for advanced EV and HEVs. Several technical advancements will still be required to meet this goal, and are likely topics for future SBIR feasibility studies.« less

Thermally Regenerative Battery with Intercalatable Electrodes and Selective Heating Means

NASA Technical Reports Server (NTRS)

Sharma, Pramod K. (Inventor); Narayanan, Sekharipuram R. (Inventor); Hickey, Gregory S. (Inventor)

2000-01-01

The battery contains at least one electrode such as graphite that intercalates a first species from the electrolyte disposed in a first compartment such as bromine to form a thermally decomposable complex during discharge. The other electrode can also be graphite which supplies another species such as lithium to the electrolyte in a second electrode compartment. The thermally decomposable complex is stable at room temperature but decomposes at elevated temperatures such as 50 C. to 150 C. The electrode compartments are separated by a selective ion permeable membrane that is impermeable to the first species. Charging is effected by selectively heating the first electrode.

Formation of Multilayer Cu Islands Embedded beneath the Surface of Graphite: Characterization and Fundamental Insights

DOE PAGES

Lii-Rosales, Ann; Han, Yong; Evans, James W.; ...

2018-02-06

Here in this paper, we present an extensive experimental study of the conditions under which Cu forms encapsulated islands under the top surface layers of graphite, as a result of physical vapor deposition of Cu on argon-ion-bombarded graphite. When the substrate is held at 800 K during deposition, conditions are optimal for formation of encapsulated multilayer Cu islands. Deposition temperatures below 600 K favor adsorbed Cu clusters, while deposition temperatures above 800 K favor a different type of feature that is probably a single-layer intercalated Cu island. The multilayer Cu islands are characterized with respect to size and shape, thicknessmore » and continuity of the graphitic overlayer, relationship to graphite steps, and stability in air. The experimental techniques are scanning tunneling microscopy and X-ray photoelectron spectroscopy. We also present an extensive study using density functional theory to compare stabilities of a wide variety of configurations of Cu atoms, Cu clusters, and Cu layers on/under the graphite surface. The only configuration that is significantly more stable under the graphite surface than on top of it, is a single Cu atom. This analysis leads us to conclude that formation of encapsulated Cu islands is kinetically driven, rather than thermodynamically driven.« less

Formation of Multilayer Cu Islands Embedded beneath the Surface of Graphite: Characterization and Fundamental Insights

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

Lii-Rosales, Ann; Han, Yong; Evans, James W.

Here in this paper, we present an extensive experimental study of the conditions under which Cu forms encapsulated islands under the top surface layers of graphite, as a result of physical vapor deposition of Cu on argon-ion-bombarded graphite. When the substrate is held at 800 K during deposition, conditions are optimal for formation of encapsulated multilayer Cu islands. Deposition temperatures below 600 K favor adsorbed Cu clusters, while deposition temperatures above 800 K favor a different type of feature that is probably a single-layer intercalated Cu island. The multilayer Cu islands are characterized with respect to size and shape, thicknessmore » and continuity of the graphitic overlayer, relationship to graphite steps, and stability in air. The experimental techniques are scanning tunneling microscopy and X-ray photoelectron spectroscopy. We also present an extensive study using density functional theory to compare stabilities of a wide variety of configurations of Cu atoms, Cu clusters, and Cu layers on/under the graphite surface. The only configuration that is significantly more stable under the graphite surface than on top of it, is a single Cu atom. This analysis leads us to conclude that formation of encapsulated Cu islands is kinetically driven, rather than thermodynamically driven.« less

Iodine Intercalation of Bundles of Single Wall Carbon Nanotubes (SWNT)

NASA Astrophysics Data System (ADS)

Grigorian, L.; Fang, S. L.; Williams, K. A.; Sumanasekera, G. U.; Dickey, E. C.; Eklund, P. C.; Pennycock, S.; Rinzler, A. G.; Smalley, R. E.

1998-03-01

We have been able to intercalate iodine into the interstitial channels within the rope lattice by direct contact of SWNT mats with molten iodine. These continuously filled channels were observed by Z-contrast STEM imaging. The intercalated iodine atoms provide a ``chemical wedge'' which expands the rope lattice as found from x-ray powder diffraction. At low doping level, Raman-active modes and photoluminescence were used to identify the intercalated species as (I_3)^-I2 linear polyiodide chains. The observed upshift of the high-frequency tangential Raman mode, as well as decreased values of four-probe electrical resistance and thermopower are all consistent with electron transfer from SWNT to iodine. At higher doping level, another iodine-SWNT compound was formed as evidenced by a different x-ray diffraction pattern and Raman spectrum. This new compound exhibits a number of new Raman lines, apparently unrelated to the intercalated iodine, in addition to the usual SWNT Raman modes. We discuss possible mechanisms responsible for activating new Raman modes in SWNT.

Operando NMR and XRD study of chemically synthesized LiCx oxidation in a dry room environment

DOE PAGES

Sacci, Robert L.; Gill, Lance W.; Hagaman, Edward W.; ...

2015-04-07

We test the stability of pre-lithiated graphite anodes for Li-ion batteries in a dry room battery processing room. The reaction between LiCx and laboratory air was followed using operando NMR and x-ray diffraction as these methods are sensitive to change in Li stoichiometry in graphite. There is minimal reactivity between LiC 6 and N 2, CO 2 or O 2; however, LiC 6 reacts with moisture to form lithium (hydr)oxide. The reaction rate follows zero-order kinetics with respects to intercalated lithium suggesting that lithium transport through the graphite is fast. The reaction mechanism occurs by sequential formation of higher stagesmore » LiC 12, then LiC 18, and then LiC 24 as the hydrolysis proceeds to the formation of Li xOH y and graphite end products. Slowing down the formation rate of the Li xOH y passivation layer stabilizes of the higher stages.« less

Purification process of natural graphite as anode for Li-ion batteries: chemical versus thermal

NASA Astrophysics Data System (ADS)

Zaghib, K.; Song, X.; Guerfi, A.; Rioux, R.; Kinoshita, K.

The intercalation of Li ions in natural graphite that was purified by chemical and thermal processes was investigated. A new chemical process was developed that involved a mixed aqueous solution containing 30% H 2SO 4 and 30% NH xF y heated to 90 °C. The results of this process are compared to those obtained by heating the natural graphite from 1500 to 2400 °C in an inert environment (thermal process). The first-cycle coulombic efficiency of the purified natural graphite obtained by the chemical process is 91 and 84% after the thermal process at 2400 °C. Grinding the natural graphite before or after purification had no significant effect on electrochemical performance at low currents. However, grinding to a very small particle size before purification permitted optimization of the size distribution of the particles, which gives rise to a more homogenous electrode. The impurities in the graphite play a role as microabrasion agents during grinding which enhances its hardness and improves its mechanical properties. Grinding also modifies the particle morphology from a 2- to a 3-D structure (similar in shape to a potato). This potato-shaped natural graphite shows high reversible capacity at high current densities (about 90% at 1 C rate). Our analysis suggests that thermal processing is considerably more expensive than the chemical process to obtain purified natural graphite.

Batteries: Overview of Battery Cathodes

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

Doeff, Marca M

2010-07-12

The very high theoretical capacity of lithium (3829 mAh/g) provided a compelling rationale from the 1970's onward for development of rechargeable batteries employing the elemental metal as an anode. The realization that some transition metal compounds undergo reductive lithium intercalation reactions reversibly allowed use of these materials as cathodes in these devices, most notably, TiS{sub 2}. Another intercalation compound, LiCoO{sub 2}, was described shortly thereafter but, because it was produced in the discharged state, was not considered to be of interest by battery companies at the time. Due to difficulties with the rechargeability of lithium and related safety concerns, however,more » alternative anodes were sought. The graphite intercalation compound (GIC) LiC{sub 6} was considered an attractive candidate but the high reactivity with commonly used electrolytic solutions containing organic solvents was recognized as a significant impediment to its use. The development of electrolytes that allowed the formation of a solid electrolyte interface (SEI) on surfaces of the carbon particles was a breakthrough that enabled commercialization of Li-ion batteries. In 1990, Sony announced the first commercial batteries based on a dual Li ion intercalation system. These devices are assembled in the discharged state, so that it is convenient to employ a prelithiated cathode such as LiCoO{sub 2} with the commonly used graphite anode. After charging, the batteries are ready to power devices. The practical realization of high energy density Li-ion batteries revolutionized the portable electronics industry, as evidenced by the widespread market penetration of mobile phones, laptop computers, digital music players, and other lightweight devices since the early 1990s. In 2009, worldwide sales of Li-ion batteries for these applications alone were US$ 7 billion. Furthermore, their performance characteristics (Figure 1) make them attractive for traction applications such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicles (EVs); a market predicted to be potentially ten times greater than that of consumer electronics. In fact, only Liion batteries can meet the requirements for PHEVs as set by the U.S. Advanced Battery Consortium (USABC), although they still fall slightly short of EV goals. In the case of Li-ion batteries, the trade-off between power and energy shown in Figure 1 is a function both of device design and the electrode materials that are used. Thus, a high power battery (e.g., one intended for an HEV) will not necessarily contain the same electrode materials as one designed for high energy (i.e., for an EV). As is shown in Figure 1, power translates into acceleration, and energy into range, or miles traveled, for vehicular uses. Furthermore, performance, cost, and abuse-tolerance requirements for traction batteries differ considerably from those for consumer electronics batteries. Vehicular applications are particularly sensitive to cost; currently, Li-ion batteries are priced at about $1000/kWh, whereas the USABC goal is $150/kWh. The three most expensive components of a Li-ion battery, no matter what the configuration, are the cathode, the separator, and the electrolyte. Reduction of cost has been one of the primary driving forces for the investigation of new cathode materials to replace expensive LiCoO{sub 2}, particularly for vehicular applications. Another extremely important factor is safety under abuse conditions such as overcharge. This is particularly relevant for the large battery packs intended for vehicular uses, which are designed with multiple cells wired in series arrays. Premature failure of one cell in a string may cause others to go into overcharge during passage of current. These considerations have led to the development of several different types of cathode materials, as will be covered in the next section. Because there is not yet one ideal material that can meet requirements for all applications, research into cathodes for Li-ion batteries is, as of this writing, a very active field.« less

Nucleation and growth kinetics for intercalated islands during deposition on layered materials with isolated pointlike surface defects

DOE PAGES

Han, Yong; Lii-Rosales, A.; Zhou, Y.; ...

2017-10-13

Theory and stochastic lattice-gas modeling is developed for the formation of intercalated metal islands in the gallery between the top layer and the underlying layer at the surface of layered materials. Our model for this process involves deposition of atoms, some fraction of which then enter the gallery through well-separated pointlike defects in the top layer. Subsequently, these atoms diffuse within the subsurface gallery leading to nucleation and growth of intercalated islands nearby the defect point source. For the case of a single point defect, continuum diffusion equation analysis provides insight into the nucleation kinetics. However, complementary tailored lattice-gas modelingmore » produces a more comprehensive and quantitative characterization. We analyze the large spread in nucleation times and positions relative to the defect for the first nucleated island. We also consider the formation of subsequent islands and the evolution of island growth shapes. The shapes reflect in part our natural adoption of a hexagonal close-packed island structure. As a result, motivation and support for the model is provided by scanning tunneling microscopy observations of the formation of intercalated metal islands in highly-ordered pyrolytic graphite at higher temperatures.« less

Imidazolium-organic solvent mixtures as electrolytes for lithium batteries

NASA Astrophysics Data System (ADS)

Chagnes, A.; Diaw, M.; Carré, B.; Willmann, P.; Lemordant, D.

γ-Butyrolactone (BL) has been mixed to the room temperature ionic liquid (RTIL) 1-butyl 3-methyl-imidazolium tetrafluoroborate (BMIBF 4) (ratio: 3/2, v/v) in the presence of lithium tetrafluoroborate (LiBF 4) for use as electrolyte in lithium-ion batteries. This mixture exhibits a larger thermal stability than the reference electrolyte EC/DEC/DMC (2/2/1) + LiPF 6 (1 M) and can be considered as a new RTIL as no free BL molecules are present in the liquid phase. The cycling ability of this electrolyte has been investigated at a graphite, a titanate oxide (Li 4Ti 5O 12) and a cobalt oxide (Li xCoO 2) electrodes. The ionic liquid is strongly reduced at the graphite electrode near 1 V and leads to the formation of a blocking film, which prevents any further cycling. The titanate oxide electrode can be cycled with a high capacity without any significant fading. Cycling of the positive cobalt oxide electrode was unsuccessfully owing to an oxidation reaction at the electrode surface, which prevents the intercalation or de-intercalation of Li ions in and from the host material. Less reactive cathode material than cobalt oxide must be employed with this RTIL.

Synthesis, characterization and biological evaluation of novel α, β unsaturated amides.

PubMed

Esmailzadeh, K; Housaindokht, M R; Moradi, A; Esmaeili, A A; Sharifi, Z

2016-05-15

Three derivatives of α,β unsaturated amides have been successfully synthesized via Ugi-four component (U-4CR) reaction. The interactions of the amides with calf thymus deoxyribonucleic acid (ct-DNA) have been investigated in the Tris-HCl buffer (pH=7.4) using viscometric, spectroscopic, thermal denaturation studies, and also molecular docking. By UV-Vis absorption spectroscopy studies, adding CT-DNA to the compound solution caused the hypochromism indicates that there are interactions between the compounds and DNA base pairs. In competitive fluorescence with methylene blue as an intercalator probe, adding compounds to DNA-MB solution caused an increase in emission spectra of the complex. This could be because of compound replacing, with similar binding mode of MB, between the DNA base pairs due to release of bonded MB molecules from DNA-MB complex. Thermal denaturation studies and viscometric experiments also indicated that all three investigated compounds bind to CT-DNA by non-classical intercalation mode. Additionally, molecular docking technique predicted partial intercalation binding mode for the compounds. Also, the highest binding energy was obtained for compound 5a. These results are in agreement with results obtained by empirical methods. Copyright © 2016 Elsevier B.V. All rights reserved.

How to get between the sheets: a review of recent works on the electrochemical exfoliation of graphene materials from bulk graphite

NASA Astrophysics Data System (ADS)

Abdelkader, A. M.; Cooper, A. J.; Dryfe, R. A. W.; Kinloch, I. A.

2015-04-01

Since the beginning of the `graphene era' post-2004, there has been significant interest in developing a high purity, high yield, and scalable fabrication route toward graphene materials for both primary research purposes and industrial production. One suitable approach to graphene production lies in the realm of electrochemical exfoliation, in which a potential difference is applied between a graphite anode/cathode in the presence of an electrolyte-containing medium. Herein we review various works on the electrochemical fabrication of graphene materials specifically through the use of electrochemical intercalation and exfoliation of a graphite source electrode, focusing on the quality and purity of products formed. We categorise the most significant works in terms of anodic and cathodic control, highlighting the merits of the respective approaches, as well as indicating the challenges associated with both procedures.

Investigation of the electrochemically active surface area and lithium diffusion in graphite anodes by a novel OsO4 staining method

NASA Astrophysics Data System (ADS)

Pfaffmann, Lukas; Birkenmaier, Claudia; Müller, Marcus; Bauer, Werner; Mitsch, Tim; Feinauer, Julian; Krämer, Yvonne; Scheiba, Frieder; Hintennach, Andreas; Schleid, Thomas; Schmidt, Volker; Ehrenberg, Helmut

2016-03-01

Negative electrodes of lithium-ion batteries generally consist of graphite-based active materials. In order to realize batteries with a high current density and therefore accelerated charging processes, the intercalation of lithium and the diffusion processes of these carbonaceous materials must be understood. In this paper, we visualized the electrochemical active surface area for three different anode materials using a novel OsO4 staining method in combination with scanning electron microscopy techniques. The diffusion behavior of these three anode materials is investigated by potentiostatic intermittent titration technique measurements. From those we determine the diffusion coefficient with and without consideration of the electrochemical active surface area.

Synthesis, physical and chemical properties, and potential applications of graphite fluoride fibers

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh; Long, Martin; Stahl, Mark

1987-01-01

Graphite fluoride fibers can be produced by fluorinating pristine or intercalated graphite fibers. The higher the degree of graphitization of the fibers, the higher the temperature needed to reach the same degree of fluorination. Pitched based fibers were fluorinated to flourine-to-carbon atom rations between 0 and 1. The graphite fluoride fibers with a fluorine-to-carbon atom ration near 1 have extensive visible structural damage. On the other hand, fluorination of fibers pretreated with bromine or fluorine and bromine result in fibers with a fluorine-to-carbon atom ratio nearly equal to 0.5 with no visible structural damage. The electrical resistivity of the fibers is dependent upon the fluorine to carbon atom ratio and ranged from .01 to 10 to the 11th ohm/cm. The thermal conductivity of these fibers ranged from 5 to 73 W/m-k, which is much larger than the thermal conductivity of glass, which is the regular filler in epoxy composites. If graphite fluoride fibers are used as a filler in epoxy or PTFE, the resulting composite may be a high thermal conductivity material with an electrical resistivity in either the insulator or semiconductor range. The electrically insulating product may provide heat transfer with lower temperature gradients than many current electrical insulators. Potential applications are presented.

Stable aqueous dispersions of functionalized multi-layer graphene by pulsed underwater plasma exfoliation of graphite

NASA Astrophysics Data System (ADS)

Meyer-Plath, Asmus; Beckert, Fabian; Tölle, Folke J.; Sturm, Heinz; Mülhaupt, Rolf

2016-02-01

A process was developed for graphite particle exfoliation in water to stably dispersed multi-layer graphene. It uses electrohydraulic shockwaves and the functionalizing effect of solution plasma discharges in water. The discharges were excited by 100 ns high voltage pulsing of graphite particle chains that bridge an electrode gap. The underwater discharges allow simultaneous exfoliation and chemical functionalization of graphite particles to partially oxidized multi-layer graphene. Exfoliation is caused by shockwaves that result from rapid evaporation of carbon and water to plasma-excited gas species. Depending on discharge energy and locus of ignition, the shockwaves cause stirring, erosion, exfoliation and/or expansion of graphite flakes. The process was optimized to produce long-term stable aqueous dispersions of multi-layer graphene from graphite in a single process step without requiring addition of intercalants, surfactants, binders or special solvents. A setup was developed that allows continuous production of aqueous dispersions of flake size-selected multi-layer graphenes. Due to the well-preserved sp2-carbon structure, thin films made from the dispersed graphene exhibited high electrical conductivity. Underwater plasma discharge processing exhibits high innovation potential for morphological and chemical modifications of carbonaceous materials and surfaces, especially for the generation of stable dispersions of two-dimensional, layered materials.

Rare earth and zinc layered hydroxide salts intercalated with the 2-aminobenzoate anion as organic luminescent sensitizer

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

Cursino, Ana Cristina Trindade, E-mail: anacursino@ufpr.br; Rives, Vicente, E-mail: vrives@usal.es; Arizaga, Gregorio Guadalupe Carbajal, E-mail: gregoriocarbajal@yahoo.com.mx

2015-10-15

Rare earth (RE = Eu, Y and Tb) and zinc layered hydroxide salts intercalated with nitrate anions were synthesized, followed by exchange with 2-aminobenzoate. The UV absorption ability was improved after intercalation/grafting in relation to that shown by the parent material. - Highlights: • Rare earth (RE = Eu, Y and Tb) and zinc layered hydroxide were synthesized. • Intercalated nitrate anions were exchanged by 2-aminobenzoate. • In all the 2-aminobenzoate containing compounds, the grafting reaction was detected. • The UV absorption ability was improved after the exchange reactions. • Rare earth hydroxide salts are potential matrixes to produce luminescentmore » materials. - Abstract: Rare earth (RE = Eu, Y and Tb) and zinc layered hydroxide salts intercalated with nitrate anions were synthesized, followed by exchange with 2-aminobenzoate. The obtained compounds were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) and ultraviolet visible (UV–vis) spectroscopies, fluorescence measurements and thermal analysis (TGA/DTA). The results from FTIR spectroscopy suggest a direct coordination of 2-aminobenzoate to the metal cations of the inorganic layered structure. The organic derivative products from the intercalation reactions absorb a broader range of UV-light in relation to that shown by the parent material; the photoluminescence measurements present a strong violet, blue and green luminescence under UV-light excitation for layered compounds with, Zn, Y and Tb, respectively. Rare earth hydroxide salts (RE-LHS) are potential alternative matrices for the immobilization of organic species to produce luminescent materials.« less

Intercalation of the layered solid acid HCa/sub 2/Nb/sub 3/O/sub 10/ by organic amines

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

Jacobson, A.J.; Johnson, J.W.; Lewandowski, J.T.

1987-01-01

Layered compounds of formula C/sub n/H/sub 2n+1/NH/sub 3/Ca/sub 2/Nb/sub 3/O/sub 10/ are formed by reaction of n-alkylamines with the solid acid HCa/sub 2/Nb/sub 3/O/sub 10/. Other organic bases such as pyridine can also be intercalated. The lattice constants of the new compounds have been determined by powder X-ray diffraction. The unit cells are tetragonal with a axes that are unchanged with variation of the intercalated amine. The c axes lengths (layer spacings) vary systematically with the hydrocarbon chain length of the alkylamine.

Promising Cell Configuration for Next-Generation Energy Storage: Li2S/Graphite Battery Enabled by a Solvate Ionic Liquid Electrolyte.

PubMed

Li, Zhe; Zhang, Shiguo; Terada, Shoshi; Ma, Xiaofeng; Ikeda, Kohei; Kamei, Yutaro; Zhang, Ce; Dokko, Kaoru; Watanabe, Masayoshi

2016-06-29

Lithium-ion sulfur batteries with a [graphite|solvate ionic liquid electrolyte|lithium sulfide (Li2S)] structure are developed to realize high performance batteries without the issue of lithium anode. Li2S has recently emerged as a promising cathode material, due to its high theoretical specific capacity of 1166 mAh/g and its great potential in the development of lithium-ion sulfur batteries with a lithium-free anode such as graphite. Unfortunately, the electrochemical Li(+) intercalation/deintercalation in graphite is highly electrolyte-selective: whereas the process works well in the carbonate electrolytes inherited from Li-ion batteries, it cannot take place in the ether electrolytes commonly used for Li-S batteries, because the cointercalation of the solvent destroys the crystalline structure of graphite. Thus, only very few studies have focused on graphite-based Li-S full cells. In this work, simple graphite-based Li-S full cells were fabricated employing electrolytes beyond the conventional carbonates, in combination with highly loaded Li2S/graphene composite cathodes (Li2S loading: 2.2 mg/cm(2)). In particular, solvate ionic liquids can act as a single-phase electrolyte simultaneously compatible with both the Li2S cathode and the graphite anode and can further improve the battery performance by suppressing the shuttle effect. Consequently, these lithium-ion sulfur batteries show a stable and reversible charge-discharge behavior, along with a very high Coulombic efficiency.

The Role of Cesium Cation in Controlling Interphasial Chemistry on Graphite Anode in Propylene Carbonate-Rich Electrolytes

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

Xiang, Hongfa; Mei, Donghai; Yan, Pengfei

2015-09-10

Propylene carbonate (PC) is seldom used in lithium-ion batteries (LIBs) due to its sustained co-intercalation into graphene structure and the eventual graphite exfoliation, despite potential advantages it brings, such as wider liquid range and lower cost. Here we discover that cesium cation (Cs+), originally used to suppress dendrite growth of Li metal anode, directs the formation of solid electrolyte interphase (SEI) on graphitic anode in PC-rich electrolytes through preferential solvation. Effective suppression of PC-decomposition and graphite-exfoliation was achieved when the ratio of ethylene carbonate (EC)/PC in electrolytes was so adjusted that the reductive decomposition of Cs+-(EC)m (1≤m≤2) complex precedes thatmore » of Li+-(PC)n (3≤n≤5). The interphase directed by Cs+ is stable, ultrathin and compact, leading to significant improvements in LIB performances. In a broader context, the accurate tailoring of SEI chemical composition by introducing a new solvation center represents a fundamental breakthrough in manipulating interfacial reactions processes that once were elusive.« less

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

Wertsching, Alan Kevin; Trantor, Troy Joseph; Ebner, Matthias Anthony

A method and device for producing secure, high-density tritium bonded with carbon. A substrate comprising carbon is provided. A precursor is intercalated between carbon in the substrate. The precursor intercalated in the substrate is irradiated until at least a portion of the precursor, preferably a majority of the precursor, is transmutated into tritium and bonds with carbon of the substrate forming bonded tritium. The resulting bonded tritium, tritium bonded with carbon, produces electrons via beta decay. The substrate is preferably a substrate from the list of substrates consisting of highly-ordered pyrolytic graphite, carbon fibers, carbon nanotunes, buckministerfullerenes, and combinations thereof.more » The precursor is preferably boron-10, more preferably lithium-6. Preferably, thermal neutrons are used to irradiate the precursor. The resulting bonded tritium is preferably used to generate electricity either directly or indirectly.« less

Electrochemical to Mechanical Energy Conversion

DTIC Science & Technology

2010-02-01

advantage of these properties . Metal alloys fit these requirements as many of them dilate in excess of 100% when alloyed with lithium. Aluminum, in...3. Woo KC, Kamitakahara WA, DiVincenzo DP, et al . Effect of In-Plane Density on the Structural and Elastic Properties of Graphite Intercalation...Further, free volume associated with the powder packing of the electrodes or the sealing process will aid in stress relaxation and creep strain. (a) (b) 35

The electrochemical performance of super P carbon black in reversible Li/Na ion uptake

NASA Astrophysics Data System (ADS)

Peng, Bo; Xu, Yaolin; Wang, Xiaoqun; Shi, Xinghua; Mulder, Fokko M.

2017-06-01

Super P carbon black (SPCB) has been widely used as a conducting additive in Li/Na ion batteries to improve the electronic conductivity. However, there has not yet been a comprehensive study on its structure and electrochemical properties for Li/Na ion uptake, though it is important to characterize its contribution in any study of active materials that uses this additive in non-negligible amounts. In this article the structure of SPCB has been characterized and a comprehensive study on the electrochemical Li/Na ion uptake capability and reaction mechanisms are reported. SPCB exhibits a considerable lithiation capacity (up to 310 mAh g-1) from the Li ion intercalation in the graphite structure. Sodiation in SPCB undergoes two stages: Na ion intercalation into the layers between the graphene sheets and the Na plating in the pores between the nano-graphitic domains, and a sodiation capacity up to 145 mAh g-1 has been achieved. Moreover, the influence of the type and content of binders on the lithiation and sodiation properties has been investigated. The cycling stability is much enhanced with sodium carboxymethyl cellulose (NaCMC) binder in the electrode and fluoroethylene carbonate (FEC) in the electrolyte; and a higher content of binder improves the Coulombic efficiency during dis-/charge.

Development of propidium iodide as a fluorescence probe for the on-line screening of non-specific DNA-intercalators in Fufang Banbianlian Injection.

PubMed

Niu, Yanyan; Li, Sensen; Lin, Zongtao; Liu, Meixian; Wang, Daidong; Wang, Hong; Chen, Shizhong

2016-09-09

Fufang Banbianlian Injection (FBI) has been widely used as an anti-inflammatory and anti-tumor prescription. To understand the relationships between its bioactive ingredients and pharmacological efficacies, our previous study has been successfully identified some DNA-binding compounds in FBI using an established on-line screening system, in which 4',6-diamidino-2-phenylindole (DAPI) was developed as a probe. However, DAPI can be only used to screen ATT-specific DNA minor groove binders, leaving the potential active intercalators unknown in FBI. As a continuation of our studies on FBI, here we present a sensitive analytical method for rapid identification and evaluation of DNA-intercalators using propidium iodide (PI) as a fluorescent probe. We have firstly established the technique of high-performance liquid chromatography-diode-array detector-multistage mass spectrometry-deoxyribonucleic acid-propidium iodide-fluorescence detector (HPLC-DAD-MS(n)-DNA-PI-FLD) system. As a result, 38 of 58 previously identified compounds in FBI were DNA-intercalation active. Interestingly, all previously reported DNA-binders also showed intercalative activities, suggesting they are dual-mode DNA-binders. Quantitative study showed that flavonoid glycosides and chlorogenic acids were the main active compounds in FBI, and displayed similar DNA-binding ability using either DAPI or PI. In addition, 13 active compounds were used to establish the structure-activity relationships. In this study, PI was developed into an on-line method for identifying DNA-intercalators for the first time, and thus it will be a useful high-throughput screening technique for other related samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of Propylene Carbonate Content in CsPF6-Containing Electrolytes on the Enhanced Performances of Graphite Electrode for Lithium-Ion Batteries

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

Zheng, Jianming; Yan, Pengfei; Cao, Ruiguo

2016-02-10

Cesium salt has been demonstrated as an efficient electrolyte additive in suppressing the lithium (Li) dendrite formation and directing the formation of an ultrathin and stable solid electrolyte interphase (SEI) even in propylene carbonate (PC)-ethylene carbonate (EC)-based electrolytes. Here, we further investigate the effect of PC content in the presence of CsPF6 additive (0.05 M) on the performances of graphite electrode in Li||graphite half cells and in graphite||LiNi0.80Co0.15Al0.05O2 (NCA) full cells. It is found that the performance of graphite electrode is also affected by PC content even though CsPF6 additive is present in the electrolytes. An optimal PC content ofmore » 20% by weight in the solvent mixtures is identified. The enhanced electrochemical performance of graphite electrode is attributed to the synergistic effects of the Cs+ additive and the PC solvent. The formation of a robust, ultrathin and compact SEI layer containing lithium-enriched species on the graphite electrode, directed by Cs+, effectively suppresses the PC co-intercalation and thus prevents the graphite exfoliation. This SEI layer is only permeable for de-solvated Li+ ions and allows fast Li+ ion transport through it, which therefore largely alleviates the Li dendrite formation on graphite electrode during lithiation even at high current densities. The presence of low-melting-point PC solvent also enables the sustainable operation of the graphite||NCA full cells under a wide spectrum of temperatures. The fundamental findings of this work shed light on the importance of manipulating/maintaining the electrode/electrolyte interphasial stability in a variety of energy storage devices.« less

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

Osiry, H.; Cano, A.; Lemus-Santana, A.A.

This contribution discusses the intercalation of imidazole and its 2-ethyl derivative, and pyridine in 2D copper nitroprusside. In the interlayer region, neighboring molecules remain interacting throu gh their dipole and quadrupole moments, which supports the solid 3D crystal structure. The crystal structure of this series of intercalation compounds was solved and refined from powder X-ray diffraction patterns complemented with spectroscopic information. The intermolecular interactions were studied from the refined crystal structures and low temperature magnetic measurements. Due to strong attractive forces between neighboring molecules, the resulting π–π cloud overlapping enables the ferromagnetic coupling between metal centers on neighboring layers, which wasmore » actually observed for the solids containing imidazole and pyridine as intercalated molecules. For these two solids, the magnetic data were properly described with a model of six neighbors. For the solid containing 2-ethylimidazole and for 2D copper nitroprusside, a model of four neighbors in a plane is sufficient to obtain a reliable data fitting. - Highlights: • Intercalation of organic molecules in 2D copper (II) nitroprusside. • Molecular properties of intercalation compounds of 2D copper (II) nitroprusside. • Magnetic properties of hybrid inorganic–organic solids. • Hybrid inorganic–organic 3D framework.« less

Two-dimensional triangular lattice and its application to lithium-intercalated layered compounds

NASA Astrophysics Data System (ADS)

Decerqueira, R. O.

1982-08-01

Good rechargeable batteries are being searched for use in electric vehicles and in energy storage during off-peak consumption periods and from solar sources. The interest in lithium intercalation compounds has been recently enhanced by the search for such batteries. The process of intercalation of lithium in several transition metal dichalcogenides can provide an emf of several volts. The progress achieved in the last decade in the investigation of these intercalates has been facilitated by the availability of the dichalcogenides as single crystals and by their chemical stability. The transition-metal dichalcogenides and their Li-intercalates are studied, with emphasis on the Li/su xTa/sub yTi/sub l-y/S2 series. The interactions between the Li atoms and the applicability of a lattice gas model to the problem of ordering of these atoms is discussed. A formulation is presented of the cluster-variation aproximation to the lattice gas problem. The single-site and the nearest-neighbor triangle basic clusters are considered as models for Li/sub x TiS2. Also a theory is presented for the effects of a random distribution of different species of host atoms, as in Ta/sub y/Ti/sub l-y/S2.

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

Han, Yong; Lii-Rosales, A.; Zhou, Y.

Theory and stochastic lattice-gas modeling is developed for the formation of intercalated metal islands in the gallery between the top layer and the underlying layer at the surface of layered materials. Our model for this process involves deposition of atoms, some fraction of which then enter the gallery through well-separated pointlike defects in the top layer. Subsequently, these atoms diffuse within the subsurface gallery leading to nucleation and growth of intercalated islands nearby the defect point source. For the case of a single point defect, continuum diffusion equation analysis provides insight into the nucleation kinetics. However, complementary tailored lattice-gas modelingmore » produces a more comprehensive and quantitative characterization. We analyze the large spread in nucleation times and positions relative to the defect for the first nucleated island. We also consider the formation of subsequent islands and the evolution of island growth shapes. The shapes reflect in part our natural adoption of a hexagonal close-packed island structure. As a result, motivation and support for the model is provided by scanning tunneling microscopy observations of the formation of intercalated metal islands in highly-ordered pyrolytic graphite at higher temperatures.« less

Size dependence effect of carbon-based anode material on intercalation characteristics of Li-ion battery

NASA Astrophysics Data System (ADS)

Anwar, Miftahul; Jupri, Dwi Rahmat; Saraswati, Teguh Endah

2017-01-01

This work aims to study the effect of the different size of Li-ion battery anode during charging state. Carbon-Based nanomaterial using arc-discharge in a liquid which is much simpler and cheaper compared to other techniques, i.e., CVD, laser vaporization, etc. The experiment was performed using intermediate DC power supply (1300 W) to produce an arc, and commercial graphite pencils (with 5 mm diameter) as negative and positive electrodes. Deionized water mixed with ethanol was used as a heat absorber. The result shows that arc discharge in deionized water could effectively produce carbon nanomaterial (i.e., nano-onions). In addition, finite element method-based simulation of the different intercalating process of Li-ion to the different shape of the anode, i.e., bulk semi-porous and porous anode materials for battery application is also presented. The results show that intercalation of Li ions depends on the anode structure due to the different potential density at anode region. This finding will provide support for design of Li-ion battery based on carbon nanomaterial

Synthesis of new oligothiophene derivatives and their intercalation compounds: Orientation effects

USGS Publications Warehouse

Ibrahim, M.A.; Lee, B.-G.; Park, N.-G.; Pugh, J.R.; Eberl, D.D.; Frank, A.J.

1999-01-01

The orientation dependence of intercalated oligothiophene derivatives in vermiculite and metal disulfides MS2 (M = Mo, Ti and Zr) on the pendant group on the thiophene ring and the host material was studied by X-ray diffraction (XRD) and solid state nuclear magnetic resonance spectroscopy. Amino and nitro derivatives of bi-, ter- and quarter-thiophenes were synthesized for the first time. The amino-oligothiophenes were intercalated into vermiculite by an exchange reaction with previously intercalated octadecylammonium vermiculite and into MS2 by the intercalation-exfoliation technique. Analysis of the XRD data indicates that a monolayer of amino-oligothiophene orients perpendicularly to the silicate surface in vermiculite and lies flat in the van der Waals gap of MS2.

Preparation of Graphene Sheets by Electrochemical Exfoliation of Graphite in Confined Space and Their Application in Transparent Conductive Films.

PubMed

Wang, Hui; Wei, Can; Zhu, Kaiyi; Zhang, Yu; Gong, Chunhong; Guo, Jianhui; Zhang, Jiwei; Yu, Laigui; Zhang, Jingwei

2017-10-04

A novel electrochemical exfoliation mode was established to prepare graphene sheets efficiently with potential applications in transparent conductive films. The graphite electrode was coated with paraffin to keep the electrochemical exfoliation in confined space in the presence of concentrated sodium hydroxide as the electrolyte, yielding ∼100% low-defect (the D band to G band intensity ratio, I D /I G = 0.26) graphene sheets. Furthermore, ozone was first detected with ozone test strips, and the effect of ozone on the exfoliation of graphite foil and the microstructure of the as-prepared graphene sheets was investigated. Findings indicate that upon applying a low voltage (3 V) on the graphite foil partially coated with paraffin wax that the coating can prevent the insufficiently intercalated graphite sheets from prematurely peeling off from the graphite electrode thereby affording few-layer (<5 layers) holey graphene sheets in a yield of as much as 60%. Besides, the ozone generated during the electrochemical exfoliation process plays a crucial role in the exfoliation of graphite, and the amount of defect in the as-prepared graphene sheets is dependent on electrolytic potential and electrode distance. Moreover, the graphene-based transparent conductive films prepared by simple modified vacuum filtration exhibit an excellent transparency and a low sheet resistance after being treated with NH 4 NO 3 and annealing (∼1.21 kΩ/□ at ∼72.4% transmittance).

Low Temperature Structure and Properties of Graphite Lamellar Compounds.

DTIC Science & Technology

1984-01-01

IV.RESULTS ACCEPTOR COMPOUNDS IV.1. Compound Syntheses All compounds were prepared by directly reacting the halide vapour with pyrographite (HOPG) in the...1983 "Caractdrisation chimique et struc- turale des compos~s graphite-trichlorure de gallium Synth. Met. 7, 125. Onn D.G., Foley G.M.T. & Fischer

Formation and chemical reactivity of carbon fibers prepared by defluorination of graphite fluoride

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh

1994-01-01

Defluorination of graphite fluoride (CFX) by heating to temperatures of 250 to 450 C in chemically reactive environments was studied. This is a new and possibly inexpensive process to produce new carbon-based materials. For example, CF 0.68 fibers, made from P-100 carbon fibers, can be defluorinated in BrH2C-CH = CH-CH2Br (1,4-dibromo-2butene) heated to 370 C, and graphitized to produce fibers with an unusually high modulus and a graphite layer structure that is healed and cross-linked. Conversely, a sulfur-doped, visibly soft carbon fiber was produced by defluorinating CF 0.9 fibers, made from P-25, in sulfur (S) vapor at 370 C and then heating to 660 C in nitrogen (N2). Furthermore, defluorination of the CF 0.68 fibers in bromine (Br2) produced fragile, structurally damaged carbon fibers. Heating these fragile fibers to 1100 C in N2 caused further structural damage, whereas heating to 150 C in bromoform (CHBr3) and then to 1100 C in N2 healed the structural defects. The defluorination product of CFX, tentatively called activated graphite, has the composition and molecular structure of graphite, but is chemically more reactive. Activated graphite is a scavenger of manganese (Mn), and can be intercalated with magnesium (Mg). Also, it can easily collect large amounts of an alloy made from copper (Cu) and type 304 stainless steel to form a composite. Finally, there are indications that activated graphite can wet metals or ceramics, thereby forming stronger composites with them than the pristine carbon fibers can form.

Industrial Applications of Graphite Fluoride Fibers

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh; Kucera, Donald

1991-01-01

Based on fluorination technology developed during 1934 to 1959, and the fiber technology developed during the 1970s, a new process was developed to produce graphite fluoride fibers. In the process, pitch based graphitized carbon fibers are at first intercalated and deintercalated several times by bromine and iodine, followed by several cycles of nitrogen heating and fluorination at 350 to 370 C. Electrical, mechanical, and thermal properties of this fiber depend on the fluorination process and the fluorine content of the graphite fluoride product. However, these properties are between those of graphite and those of PTFE (Teflon). Therefore, it is considered to be a semiplastic. The physical properties suggest that this new material may have many new and unexplored applications. For example, it can be a thermally conductive electrical insulator. Its coefficient of thermal expansion (CTE) can be adjusted to match that of silicon, and therefore, it can be a heat sinking printed circuit board which is CTE compatible with silicon. Using these fibers in printed circuit boards may provide improved electrical performance and reliability of the electronics on the board over existing designs. Also, since it releases fluorine at 300 C or higher, it can be used as a material to store fluorine and to conduct fluorination. This application may simplify the fluorination process and reduce the risk of handling fluorine.

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

Antisite occupation induced single anionic redox chemistry and structural stabilization of layered sodium chromium sulfide

DOE PAGES

Shadike, Zulipiya; Zhou, Yong -Ning; Chen, Lan -Li; ...

2017-08-30

The intercalation compounds with various electrochemically active or inactive elements in the layered structure have been the subject of increasing interest due to their high capacities, good reversibility, simple structures and ease of synthesis. However, their reversible intercalation/deintercalation redox chemistries in all previous compounds involve a single cationic redox reaction or a cumulative cationic and anionic redox reaction. Here we report an anionic redox only chemistry and structural stabilization of layered sodium chromium sulfide. It is discovered that sulfur in sodium chromium sulfide is electrochemical active undergoing oxidation/reduction of sulfur rather than chromium. Significantly, sodium ions can successfully move outmore » and into without changing its lattice parameter c, which is explained in terms of the occurrence of chromium/sodium vacancy antisite during desodiation and sodiation processes. Here, our present work not only enriches the electrochemistry of layered intercalation compounds, but also extends the scope of investigation on high-capacity electrodes.« less

Antisite occupation induced single anionic redox chemistry and structural stabilization of layered sodium chromium sulfide

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

Shadike, Zulipiya; Zhou, Yong -Ning; Chen, Lan -Li

The intercalation compounds with various electrochemically active or inactive elements in the layered structure have been the subject of increasing interest due to their high capacities, good reversibility, simple structures and ease of synthesis. However, their reversible intercalation/deintercalation redox chemistries in all previous compounds involve a single cationic redox reaction or a cumulative cationic and anionic redox reaction. Here we report an anionic redox only chemistry and structural stabilization of layered sodium chromium sulfide. It is discovered that sulfur in sodium chromium sulfide is electrochemical active undergoing oxidation/reduction of sulfur rather than chromium. Significantly, sodium ions can successfully move outmore » and into without changing its lattice parameter c, which is explained in terms of the occurrence of chromium/sodium vacancy antisite during desodiation and sodiation processes. Here, our present work not only enriches the electrochemistry of layered intercalation compounds, but also extends the scope of investigation on high-capacity electrodes.« less

A Novel Ultrafast Rechargeable Multi-Ions Battery.

PubMed

Wang, Shuai; Jiao, Shuqiang; Tian, Donghua; Chen, Hao-Sen; Jiao, Handong; Tu, Jiguo; Liu, Yingjun; Fang, Dai-Ning

2017-04-01

An ultrafast rechargeable multi-ions battery is presented, in which multi-ions can electrochemically intercalate into graphite layers, exhibiting a high reversible discharge capacity of ≈100 mAh g -1 and a Coulombic efficiency of ≈99% over hundreds of cycles at a high current density. The results may open up a new paradigm for multi-ions-based electrochemical battery technologies and applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Visualizing the chemistry and structure dynamics in lithium-ion batteries by in-situ neutron diffraction

PubMed Central

Wang, Xun-Li; An, Ke; Cai, Lu; Feng, Zhili; Nagler, Stephen E.; Daniel, Claus; Rhodes, Kevin J.; Stoica, Alexandru D.; Skorpenske, Harley D.; Liang, Chengdu; Zhang, Wei; Kim, Joon; Qi, Yue; Harris, Stephen J.

2012-01-01

We report an in-situ neutron diffraction study of a large format pouch battery cell. The succession of Li-Graphite intercalation phases was fully captured under an 1C charge-discharge condition (i.e., charge to full capacity in 1 hour). However, the lithiation and dilithiation pathways are distinctively different and, unlike in slowing charging experiments with which the Li-Graphite phase diagram was established, no LiC24 phase was found during charge at 1C rate. Approximately 75 mol. % of the graphite converts to LiC6 at full charge, and a lattice dilation as large as 4% was observed during a charge-discharge cycle. Our work demonstrates the potential of in-situ, time and spatially resolved neutron diffraction study of the dynamic chemical and structural changes in “real-world” batteries under realistic cycling conditions, which should provide microscopic insights on degradation and the important role of diffusion kinetics in energy storage materials. PMID:23087812

Supercritical fluid extraction of bi & multi-layer graphene sheets from graphite by using exfoliation technique

NASA Astrophysics Data System (ADS)

Xavier, Gauravi; Dave, Bhoomi; Khanna, Sakshum

2018-05-01

In recent times, researchers have turned to explore the possibility of using Supercritical Fluid (SCFs) system to penetrate into the inert-gaping of graphite and exfoliate it into a number of layer graphene sheets. The supercritical fluid holds excellent wetting surfaces with low interfacial tension and high diffusion coefficients. Although SCFs exfoliation approach looks promising to developed large scale & low-cost graphene sheet but has not received much attention. To arouse interest and reflection on this approach, this review is organized to summarize the recent progress in graphene production by SCF technology. Here we present the simplest route to obtained layers of graphene sheets by intercalating and exfoliating graphite using supercritical CO2 processing. The layers graphene nano-sheets were collected in dichloromethane (DCM) solution which prevents the restocking of sheets. The obtained graphene sheets show the desired characteristics and thus can be used in physical, chemical and biological sciences. Thus this method provides an effortless and eco-friendly approach for the synthesis of layers of graphene sheets.

Na-Ion Battery Anodes: Materials and Electrochemistry.

PubMed

Luo, Wei; Shen, Fei; Bommier, Clement; Zhu, Hongli; Ji, Xiulei; Hu, Liangbing

2016-02-16

The intermittent nature of renewable energy sources, such as solar and wind, calls for sustainable electrical energy storage (EES) technologies for stationary applications. Li will be simply too rare for Li-ion batteries (LIBs) to be used for large-scale storage purposes. In contrast, Na-ion batteries (NIBs) are highly promising to meet the demand of grid-level storage because Na is truly earth abundant and ubiquitous around the globe. Furthermore, NIBs share a similar rocking-chair operation mechanism with LIBs, which potentially provides high reversibility and long cycling life. It would be most efficient to transfer knowledge learned on LIBs during the last three decades to the development of NIBs. Following this logic, rapid progress has been made in NIB cathode materials, where layered metal oxides and polyanionic compounds exhibit encouraging results. On the anode side, pure graphite as the standard anode for LIBs can only form NaC64 in NIBs if solvent co-intercalation does not occur due to the unfavorable thermodynamics. In fact, it was the utilization of a carbon anode in LIBs that enabled the commercial successes. Anodes of metal-ion batteries determine key characteristics, such as safety and cycling life; thus, it is indispensable to identify suitable anode materials for NIBs. In this Account, we review recent development on anode materials for NIBs. Due to the limited space, we will mainly discuss carbon-based and alloy-based anodes and highlight progress made in our groups in this field. We first present what is known about the failure mechanism of graphite anode in NIBs. We then go on to discuss studies on hard carbon anodes, alloy-type anodes, and organic anodes. Especially, the multiple functions of natural cellulose that is used as a low-cost carbon precursor for mass production and as a soft substrate for tin anodes are highlighted. The strategies of minimizing the surface area of carbon anodes for improving the first-cycle Coulombic efficiency are also outlined, where graphene oxide was employed as dehydration agent and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was used to unzip wood fiber. Furthermore, surface modification by atomic layer deposition technology is introduced, where we discover that a thin layer of Al2O3 can function to encapsulate Sn nanoparticles, leading to a much enhanced cycling performance. We also highlight recent work about the phosphorene/graphene anode, which outperformed other anodes in terms of capacity. The aromatic organic anode is also studied as anode with very high initial sodiation capacity. Furthermore, electrochemical intercalation of Na ions into reduced graphene oxide is applied for fabricating transparent conductors, demonstrating the great feasibility of Na ion intercalation for optical applications.

The electronic properties of SWNTs intercalated by electron acceptors

NASA Astrophysics Data System (ADS)

Chernysheva, M. V.; Kiseleva, E. A.; Verbitskii, N. I.; Eliseev, A. A.; Lukashin, A. V.; Tretyakov, Yu. D.; Savilov, S. V.; Kiselev, N. A.; Zhigalina, O. M.; Kumskov, A. S.; Krestinin, A. V.; Hutchison, J. L.

2008-05-01

Here we report synthesis of Chal@SWNT nanocomposites (where Chal=S, Se and Te) and the impact of the intercalated electron-acceptor compounds on the electronic properties of SWNTs. The chalcogens were introduced to the channels of single-walled carbon nanotubes by molten media technique via impregnation of pre-opened SWNTs with melted guest compounds in vacuum. HRTEM imaging confirms the filling of nanotube channels by continuous nanostructures of corresponding chalcogens. The strong influence of incorporated matter on the electronic properties of the SWNTs was detected by Raman spectroscopy.

Spinel compounds as multivalent battery cathodes: A systematic evaluation based on ab initio calculations

DOE PAGES

Liu, Miao; Rong, Ziqin; Malik, Rahul; ...

2014-12-16

In this study, batteries that shuttle multivalent ions such as Mg 2+ and Ca 2+ ions are promising candidates for achieving higher energy density than available with current Li-ion technology. Finding electrode materials that reversibly store and release these multivalent cations is considered a major challenge for enabling such multivalent battery technology. In this paper, we use recent advances in high-throughput first-principles calculations to systematically evaluate the performance of compounds with the spinel structure as multivalent intercalation cathode materials, spanning a matrix of five different intercalating ions and seven transition metal redox active cations. We estimate the insertion voltage, capacity,more » thermodynamic stability of charged and discharged states, as well as the intercalating ion mobility and use these properties to evaluate promising directions. Our calculations indicate that the Mn 2O 4 spinel phase based on Mg and Ca are feasible cathode materials. In general, we find that multivalent cathodes exhibit lower voltages compared to Li cathodes; the voltages of Ca spinels are ~0.2 V higher than those of Mg compounds (versus their corresponding metals), and the voltages of Mg compounds are ~1.4 V higher than Zn compounds; consequently, Ca and Mg spinels exhibit the highest energy densities amongst all the multivalent cation species. The activation barrier for the Al³⁺ ion migration in the Mn₂O₄ spinel is very high (~1400 meV for Al 3+ in the dilute limit); thus, the use of an Al based Mn spinel intercalation cathode is unlikely. Amongst the choice of transition metals, Mn-based spinel structures rank highest when balancing all the considered properties.« less

Graphene nanosheets and graphite oxide as promising adsorbents for removal of organic contaminants from aqueous solution.

PubMed

Ji, Liangliang; Chen, Wei; Xu, Zhaoyi; Zheng, Shourong; Zhu, Dongqiang

2013-01-01

Graphenes are an emerging class of carbon nanomaterials whose adsorption properties toward organic compounds have not been well understood. In the present study, graphene nanosheets were prepared by reoxidation and abrupt heating of graphite oxide, which was prepared by sequential chemical oxidation of commercial nonporous graphite powder. Adsorption properties of three aromatic compounds (naphthalene, 2-naphthol, and 1-naphthylamine) and one pharmaceutical compound (tylosin) on graphene nanosheets and graphite oxide were examined to explore the potential of these two adsorbents for the removal of organic contaminants from aqueous solutions. Compared with the literature data of adsorption on carbon nanotubes, adsorption of bulky, flexible tylosin on graphene nanosheets exhibited markedly faster adsorption kinetics, which can be attributed to their opened-up layer structure. Graphene nanosheets and graphite oxide showed similar sequences of adsorption affinity: 1-naphthylamine > 2-naphthol > tylosin > naphthalene (with much larger differences observed on graphite oxide). It was proposed that the strong adsorption of the three aromatic compounds was mainly due to π-π electron donor-acceptor interactions with the graphitic surfaces of adsorbents. Additionally, Lewis acid-base interaction was likely an important factor contributing to the strong adsorption of 1-naphthylamine and tylosin, especially for the O-functionality-abundant graphite oxide. After being normalized on the basis of adsorbent surface area, adsorption affinities of all four tested adsorbates on graphene nanosheets were very close to those on nonporous graphite powder, reflecting complete accessibility of the adsorbent surface area in adsorption. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Electrochemical oxygen intercalation into Sr2IrO4

NASA Astrophysics Data System (ADS)

Fruchter, L.; Brouet, V.; Colson, D.; Moussy, J.-B.; Forget, A.; Li, Z. Z.

2018-01-01

Oxygen was electrochemically intercalated into Sr2IrO4 sintered samples, single crystals and a thin film. We estimate the diffusion length to a few μm and the concentration of the intercalated oxygen to δ ≃ 0.01. The latter is thus much smaller than for the cuprate and nickelate parent compounds, for which δ > 0.1 is obtained, which could be a consequence of larger steric effects. The influence of the oxygen doping state on resistivity is small, indicating also a poor charge transfer to the conduction band. It is shown that electrochemical intercalation of oxygen may also contribute to doping, when gating thin films with ionic liquid in the presence of water.

Probing the recognition surface of a DNA triplex: binding studies with intercalator-neomycin conjugates.

PubMed

Xue, Liang; Xi, Hongjuan; Kumar, Sunil; Gray, David; Davis, Erik; Hamilton, Paris; Skriba, Michael; Arya, Dev P

2010-07-06

Thermodynamic studies on the interactions between intercalator-neomycin conjugates and a DNA polynucleotide triplex [poly(dA).2poly(dT)] were conducted. To draw a complete picture of such interactions, naphthalene diimide-neomycin (3) and anthraquinone-neomycin (4) conjugates were synthesized and used together with two other analogues, previously synthesized pyrene-neomycin (1) and BQQ-neomycin (2) conjugates, in our investigations. A combination of experiments, including UV denaturation, circular dichroism (CD) titration, differential scanning calorimetry (DSC), and isothermal titration calorimetry (ITC), revealed that all four conjugates (1-4) stabilized poly(dA).2poly(dT) much more than its parent compound, neomycin. UV melting experiments clearly showed that the temperature (T(m3-->2)) at which poly(dA).2poly(dT) dissociated into poly(dA).poly(dT) and poly(dT) increased dramatically (>12 degrees C) in the presence of intercalator-neomycin conjugates (1-4) even at a very low concentration (2 muM). In contrast to intercalator-neomycin conjugates, the increment of T(m3-->2) of poly(dA).2poly(dT) induced by neomycin was negligible under the same conditions. The binding preference of intercalator-neomycin conjugates (1-4) to poly(dA).2poly(dT) was also confirmed by competition dialysis and a fluorescent intercalator displacement assay. Circular dichroism titration studies revealed that compounds 1-4 had slightly larger binding site size ( approximately 7-7.5) with poly(dA).2poly(dT) as compared to neomycin ( approximately 6.5). The thermodynamic parameters of these intercalator-neomycin conjugates with poly(dA).2poly(dT) were derived from an integrated van't Hoff equation using the T(m3-->2) values, the binding site size numbers, and other parameters obtained from DSC and ITC. The binding affinity of all tested ligands with poly(dA).2poly(dT) increased in the following order: neomycin < 1 < 3 < 4 < 2. Among them, the binding constant [(2.7 +/- 0.3) x 10(8) M(-1)] of 2 with poly(dA).2poly(dT) was the highest, almost 1000-fold greater than that of neomycin. The binding of compounds 1-4 with poly(dA).2poly(dT) was mostly enthalpy-driven and gave negative DeltaC(p) values. The results described here suggest that the binding affinity of intercalator-neomycin conjugates for poly(dA).2poly(dT) increases as a function of the surface area of the intercalator moiety.

Piezo-Electrochemical Transducer Effect (PECT) Intercalated Graphite Micro-Electromechanical Actuators

DTIC Science & Technology

2007-11-01

fabrication foibles, and the AFRL/SN staff for being there when I couldn’t get things in the cleanroom to work. To Dr. Benji Maruyama, the insight into...Knowing these limitations, one can think back to 1974, when one man was the childhood hero of thousands of American youth. He wasn’t superman , he was...presents an example of how a single hot arm polysilicon electrothermal actuator operates. These characteristics apply equally well, albeit with

Fluorinated graphite fibers as a new engineering material: Promises and challenges

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh; Long, Martin

1989-01-01

Pitch based graphitized carbon fibers with electrical resistivity of 300 micro-Ohm/cm were brominated and partially debrominated to 18 percent bromine at room temperature, and then fluorinated at 300 to 450 C, either continuously or intermittently for several cycles. In addition, on fluorine and titanium fluoride intercalated fiber sample was fluorinated at 270 C from the same fiber source. The mass and conductivity of the brominated-debrominated then fluorinated fibers (with fluorine-to-carbon atom ratio of 0.54 or higher) stabilized at room temperature air in a few days. However, at 200 C, these values decreased rapidly and then more slowly, throughout a 2-week test period. The electrically insulative or semiconductive fibers were found to be compatible with epoxy and have the fluorine-to-carbon atom ratio of 0.65 to 0.68, thermal conductivity of 5 to 24 W/m-K, electrical resistivity of 10(exp 4) to 10(exp 11) Ohm/cm, tensile strength of 70 to 150 ksi, Young's modulus of 20 to 30 msi, and CTE (coefficient of thermal expansion) values of 7 ppm/deg C. Data of these physical property values are preliminary. However, it is concluded that these physical properties can be tailor-made. They depend largely on the fluorine content of the final products and the intercalant in the fibers before fluorination, and, to a smaller extent, on the fluorination temperature histogram.

Optimization and Domestic Sourcing of Lithium Ion Battery Anode Materials

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

Wood, III, D. L.; Yoon, S.

2012-10-25

The purpose of this Cooperative Research and Development Agreement (CRADA) between ORNL and A123Systems, Inc. was to develop a low-temperature heat treatment process for natural graphite based anode materials for high-capacity and long-cycle-life lithium ion batteries. Three major problems currently plague state-of-the-art lithium ion battery anode materials. The first is the cost of the artificial graphite, which is heat-treated well in excess of 2000°C. Because of this high-temperature heat treatment, the anode active material significantly contributes to the cost of a lithium ion battery. The second problem is the limited specific capacity of state-of-the-art anodes based on artificial graphites, whichmore » is only about 200-350 mAh/g. This value needs to be increased to achieve high energy density when used with the low cell-voltage nanoparticle LiFePO4 cathode. Thirdly, the rate capability under cycling conditions of natural graphite based materials must be improved to match that of the nanoparticle LiFePO4. Natural graphite materials contain inherent crystallinity and lithium intercalation activity. They hold particular appeal, as they offer huge potential for industrial energy savings with the energy costs essentially subsidized by geological processes. Natural graphites have been heat-treated to a substantially lower temperature (as low as 1000-1500°C) and used as anode active materials to address the problems described above. Finally, corresponding graphitization and post-treatment processes were developed that are amenable to scaling to automotive quantities.« less

Effect of fluroine content, atmosphere, and burnishing technique on the lubricating properties of graphite fluoride

NASA Technical Reports Server (NTRS)

Fusaro, R. L.

1974-01-01

Eight different graphite fluoride compounds with fluorine to carbon ratios varying from x = 0.25 to 1.1 were evaluated as burnished films in order to determine the effect of fluorine content on the solid lubricant properties of graphite fluoride. For comparison, similar experiments were conducted on graphite burnished films. It was found that even a small amount of fluorine in graphite fluoride (CF0.25)n improved the lubricating properties of graphite. However, such factors as burnishing atmosphere, burnishing technique, test atmosphere, and specimen temperature affected the results as much as varying the fluorine to carbon ratio of the compound. Best life was found for films that were machined burnished in moist air and tested in moist air.

Graphite fluoride lubrication: The effect of fluorine content, atmosphere, and burnishing technique

NASA Technical Reports Server (NTRS)

Fusaro, R. L.

1975-01-01

Eight different graphite fluoride compounds with fluorine to carbon ratios varying from x = 0.25 to 1.1 were evaluated as burnished films in order to determine the effect of fluorine content on the solid lubricant properties of graphite fluoride. For comparison, similar experiments were conducted on graphite burnished films. It was found that even a small amount of fluorine in graphite fluoride (CF sub 0.25) sub n improved the lubricating properties of graphite. Such factors as burnishing atmosphere, burnishing technique, test atmosphere, and specimen temperature affected the results as much as varying the fluorine to carbon ratio of the compound. Best life was found for films that were machine-burnished in moist air and tested in moist air.

Gaussian approximation potential modeling of lithium intercalation in carbon nanostructures

NASA Astrophysics Data System (ADS)

Fujikake, So; Deringer, Volker L.; Lee, Tae Hoon; Krynski, Marcin; Elliott, Stephen R.; Csányi, Gábor

2018-06-01

We demonstrate how machine-learning based interatomic potentials can be used to model guest atoms in host structures. Specifically, we generate Gaussian approximation potential (GAP) models for the interaction of lithium atoms with graphene, graphite, and disordered carbon nanostructures, based on reference density functional theory data. Rather than treating the full Li-C system, we demonstrate how the energy and force differences arising from Li intercalation can be modeled and then added to a (prexisting and unmodified) GAP model of pure elemental carbon. Furthermore, we show the benefit of using an explicit pair potential fit to capture "effective" Li-Li interactions and to improve the performance of the GAP model. This provides proof-of-concept for modeling guest atoms in host frameworks with machine-learning based potentials and in the longer run is promising for carrying out detailed atomistic studies of battery materials.

Synthesis of soluble graphite and graphene.

PubMed

Kelly, K F; Billups, W E

2013-01-15

Because of graphene's anticipated applications in electronics and its thermal, mechanical, and optical properties, many scientists and engineers are interested in this material. Graphene is an isolated layer of the π-stacked hexagonal allotrope of carbon known as graphite. The interlayer cohesive energy of graphite, or exfoliation energy, that results from van der Waals attractions over the interlayer spacing distance of 3.34 Å (61 meV/C atom) is many times weaker than the intralayer covalent bonding. Since graphene itself does not occur naturally, scientists and engineers are still learning how to isolate and manipulate individual layers of graphene. Some researchers have relied on the physical separation of the sheets, a process that can sometimes be as simple as peeling of sheets from crystalline graphite using Scotch tape. Other researchers have taken an ensemble approach, where they exploit the chemical conversion of graphite to the individual layers. The typical intermediary state is graphite oxide, which is often produced using strong oxidants under acidic conditions. Structurally, researchers hypothesize that acidic functional groups functionalize the oxidized material at the edges and a network of epoxy groups cover the sp(2)-bonded carbon network. The exfoliated material formed under these conditions can be used to form dispersions that are usually unstable. However, more importantly, irreversible defects form in the basal plane during oxidation and remain even after reduction of graphite oxide back to graphene-like material. As part of our interest in the dissolution of carbon nanomaterials, we have explored the derivatization of graphite following the same procedures that preserve the sp(2) bonding and the associated unique physical and electronic properties in the chemical processing of single-walled carbon nanotubes. In this Account, we describe efficient routes to exfoliate graphite either into graphitic nanoparticles or into graphene without resorting to oxidation. Our exfoliation process involves the intercalation of lithium into bulk graphite to yield graphene sheets reduced by the lithium. We can alkylate the resulting graphite salt reductively using solubilizing dodecyl groups. By probe microscopy, we show that these groups are attached covalently only at the graphitic edges.

Intercalation of paracetamol into the hydrotalcite-like host

NASA Astrophysics Data System (ADS)

Kovanda, František; Maryšková, Zuzana; Kovář, Petr

2011-12-01

Hydrotalcite-like compounds are often used as host structures for intercalation of various anionic species. The product intercalated with the nonionic, water-soluble pharmaceuticals paracetamol, N-(4-hydroxyphenyl)acetamide, was prepared by rehydration of the Mg-Al mixed oxide obtained by calcination of hydrotalcite-like precursor at 500 °C. The successful intercalation of paracetamol molecules into the interlayer space was confirmed by powder X-ray diffraction and infrared spectroscopy measurements. Molecular simulations showed that the phenolic hydroxyl groups of paracetamol interact with hydroxide sheets of the host via the hydroxyl groups of the positively charged sites of Al-containing octahedra; the interlayer water molecules are located mostly near the hydroxide sheets. The arrangement of paracetamol molecules in the interlayer is rather disordered and interactions between neighboring molecules cause their tilting towards the hydroxide sheets. Dissolution tests in various media showed slower release of paracetamol intercalated in the hydrotalcite-like host in comparison with tablets containing the powdered pharmaceuticals.

Effect of adsorbed/intercalated anionic dyes into the mechanical properties of PVA: layered zinc hydroxide nitrate nanocomposites.

PubMed

Marangoni, Rafael; Mikowski, Alexandre; Wypych, Fernando

2010-11-15

Zinc hydroxide nitrate (ZHN) was adsorbed with anions of blue dyes (Chicago sky blue, CSB; Evans blue, EB; and Niagara blue, NB) and intercalated with anions of orange dyes (Orange G, OG; Orange II, OII; methyl orange, MO). Transparent, homogeneous and colored nanocomposite films were obtained by casting after dispersing the pigments (dye-intercalated/adsorbed into LHSs) into commercial poly(vinyl alcohol) (PVA). The films were characterized by XRD, UV-Vis spectroscopy, and mechanical testing. The mechanical properties of the PVA compounded with the dye-intercalated/adsorbed ZHN were evaluated, and reasonable increases in Young's modulus and ultimate tensile strength were observed, depending on the amount and choice of layered filler. These results demonstrate the possibility of using a new class of layered hydroxide salts intercalated and adsorbed with anionic dyes to prepare multifunctional polymer nanocomposite materials. Copyright © 2010 Elsevier Inc. All rights reserved.

High-density sodium and lithium ion battery anodes from banana peels.

PubMed

Lotfabad, Elmira Memarzadeh; Ding, Jia; Cui, Kai; Kohandehghan, Alireza; Kalisvaart, W Peter; Hazelton, Michael; Mitlin, David

2014-07-22

Banana peel pseudographite (BPPG) offers superb dual functionality for sodium ion battery (NIB) and lithium ion battery (LIB) anodes. The materials possess low surface areas (19-217 m(2) g(-1)) and a relatively high electrode packing density (0.75 g cm(-3) vs ∼1 g cm(-3) for graphite). Tested against Na, BPPG delivers a gravimetric (and volumetric) capacity of 355 mAh g(-1) (by active material ∼700 mAh cm(-3), by electrode volume ∼270 mAh cm(-3)) after 10 cycles at 50 mA g(-1). A nearly flat ∼200 mAh g(-1) plateau that is below 0.1 V and a minimal charge/discharge voltage hysteresis make BPPG a direct electrochemical analogue to graphite but with Na. A charge capacity of 221 mAh g(-1) at 500 mA g(-1) is degraded by 7% after 600 cycles, while a capacity of 336 mAh g(-1) at 100 mAg(-1) is degraded by 11% after 300 cycles, in both cases with ∼100% cycling Coulombic efficiency. For LIB applications BPPG offers a gravimetric (volumetric) capacity of 1090 mAh g(-1) (by material ∼2200 mAh cm(-3), by electrode ∼900 mAh cm(-3)) at 50 mA g(-1). The reason that BPPG works so well for both NIBs and LIBs is that it uniquely contains three essential features: (a) dilated intergraphene spacing for Na intercalation at low voltages; (b) highly accessible near-surface nanopores for Li metal filling at low voltages; and (c) substantial defect content in the graphene planes for Li adsorption at higher voltages. The <0.1 V charge storage mechanism is fundamentally different for Na versus for Li. A combination of XRD and XPS demonstrates highly reversible Na intercalation rather than metal underpotential deposition. By contrast, the same analysis proves the presence of metallic Li in the pores, with intercalation being much less pronounced.

Evaluation and optimization of the conditions for an improved ferulic acid intercalation into a synthetic lamellar anionic clay.

PubMed

Schoubben, Aurélie; Blasi, Paolo; Giovagnoli, Stefano; Nocchetti, Morena; Ricci, Maurizio; Perioli, Luana; Rossi, Carlo

2006-03-01

The aim of the study is to optimize the intercalation conditions of ferulic acid (FERH), an antioxidant compound, into Mg-Al-hydrotalcite for a safe skin photoprotection. The intercalation products were prepared incubating hydrotalcite (HTlc) in aqueous solutions of FERH sodium salt at different temperatures over 4 and 8 days. Quantitative determination of intercalated FERH was performed by thermogravimetric analysis and morphology by scanning electron microscopy (SEM). FERH stability study was carried out at different pHs and temperatures. FERH was analyzed by reversed phase-high-performance liquid chromatography. Response surface methods (RSMs) were used to assess optimal intercalation conditions and FERH stability. In all intercalation products, FERH content was found to be about 48% w/w except when the intercalation process was carried out at 52 degrees C for 8 days and at 60 degrees C for both 4 and 8 days, which resulted to be 40.39, 39.99, and 34.99%, respectively. The RSM designs showed that intercalation improvement can be achieved by working at pH 6, at temperatures below 40 degrees C, and over 4 days of incubation. The optimal conditions for a proper FERH intercalation were assessed. The development of a new optimized protocol may improve HTlc-FER complex performances and safety by augmenting dosage and reducing the presence of harmful reactive species in the final formulation.

Hierarchical Porous Intercalation-Type V2 O3 as High-Performance Anode Materials for Li-Ion Batteries.

PubMed

Liu, Pengcheng; Zhu, Kongjun; Xu, Yuan; Bian, Kan; Wang, Jing; Tai, Guo'an; Gao, Yanfeng; Luo, Hongjie; Lu, Li; Liu, Jinsong

2017-06-01

As intercalation-type anode materials for Li-ion batteries (LIBs), the commercially used graphite and Li 4 Ti 5 O 12 exhibit good cycling and rate properties, but their theoretical specific capacities are too low to meet the ever-growing demands of high-energy applications such as electric vehicles. Therefore, the development of new intercalation-type anode materials with larger capacity is very desirable. Herein, we design and synthesize novel 3 D hierarchical porous V 2 O 3 @C micro/nanostructures consisting of crumpled nanosheets, through self-reduction under annealing from the structurally similar VO 2 (B)@C precursors without the addition of any other reducing reagent or gas. Excitingly, it is found for the first time through ex situ XRD technology that V 2 O 3 is a new, promising intercalation-type anode material for LIBs with a high capacity. V 2 O 3 @C micro/nanostructures can deliver a large capacity of 732 mAh g -1 without capacity loss at 100 mA g -1 even after 136 cycles, as well as exhibiting excellent cycling and rate performances. The application of V 2 O 3 for Na-ion batteries (NIBs) is elaborated for the first time, and excitingly, it is found that V 2 O 3 @C micro/nanostructures may be promising anode materials for NIBs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Removal of metals from aqueous solution and sea water by functionalized graphite nanoplatelets based electrodes.

PubMed

Mishra, Ashish Kumar; Ramaprabhu, S

2011-01-15

In the present wok, we have demonstrated the simultaneous removal of sodium and arsenic (pentavalent and trivalent) from aqueous solution using functionalized graphite nanoplatelets (f-GNP) based electrodes. In addition, these electrodes based water filter was used for multiple metals removal from sea water. Graphite nanoplatelets (GNP) were prepared by acid intercalation and thermal exfoliation. Functionalization of GNP was done by further acid treatment. Material was characterized by different characterization techniques. Performance of supercapacitor based water filter was analyzed for the removal of high concentration of arsenic (trivalent and pentavalent) and sodium as well as for desalination of sea water, using cyclic voltametry (CV) and inductive coupled plasma-optical emission spectroscopy (ICP-OES) techniques. Adsorption isotherms and kinetic characteristics were studied for the simultaneous removal of sodium and arsenic (both trivalent and pentavalent). Maximum adsorption capacities of 27, 29 and 32 mg/g for arsenate, arsenite and sodium were achieved in addition to good removal efficiency for sodium, magnesium, calcium and potassium from sea water. Copyright © 2010 Elsevier B.V. All rights reserved.

Vertical distribution of overpotentials and irreversible charge losses in lithium ion battery electrodes.

PubMed

Klink, Stefan; Schuhmann, Wolfgang; La Mantia, Fabio

2014-08-01

Porous lithium ion battery electrodes are characterized using a vertical distribution of cross-currents. In an appropriate simplification, this distribution can be described by a transmission line model (TLM) consisting of infinitely thin electrode layers. To investigate the vertical distribution of currents, overpotentials, and irreversible charge losses in a porous graphite electrode in situ, a multi-layered working electrode (MWE) was developed as the experimental analogue of a TLM. In this MWE, each layer is in ionic contact but electrically insulated from the other layers by a porous separator. It was found that the negative graphite electrodes get lithiated and delithiated stage-by-stage and layer-by-layer. Several mass-transport- as well as non-mass-transport-limited processes could be identified. Local current densities can reach double the average, especially on the outermost layer at the beginning of each intercalation stage. Furthermore, graphite particles close to the counter electrode act as "electrochemical sieve" reducing the impurities present in the electrolyte such as water. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photoemission studies of fluorine functionalized porous graphitic carbon

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

Ganegoda, Hasitha; Olive, Daniel; Cheng, Lidens

2012-03-01

Porous graphitic carbon (PGC) has unique properties desirable for liquid chromatography applications when used as a stationary phase. The polar retention effect on graphite (PREG) allows efficient separation of polar and non-polar solutes. Perfluorinated hydrocarbons however lack polarizabilty and display strong lipo- and hydrophobicity, hence common lipophilic and hydrophilic analytes have low partition coefficiency in fluorinated stationary phases. Attractive interaction between fluorinated stationary phase and fluorinated analytes results in strong retention compared to non-fluorinated analytes. In order to change the selectivities of PGC, it is necessary to develop a bonded PGC stationary phase. In this study, we have synthesized perfluorinated,more » PGC using hepatadecafluoro-1-iodooctane, under different temperature conditions. Surface functionalization of the raw material was studied using photoelectron spectroscopy (PES). Results indicate the existence of fluorine containing functional groups, -CF, -CF{sub 2} along with an intercalated electron donor species. Multiple oxygen functional groups were also observed, likely due to the presence of oxygen in the starting material. These oxygen species may be responsible for significant modifications to planer and tetrahedral carbon ratios.« less

Self-Printing on Graphitic Nanosheets with Metal Borohydride Nanodots for Hydrogen Storage

NASA Astrophysics Data System (ADS)

Li, Yongtao; Ding, Xiaoli; Zhang, Qingan

2016-08-01

Although the synthesis of borohydride nanostructures is sufficiently established for advancement of hydrogen storage, obtaining ultrasmall (sub-10 nm) metal borohydride nanocrystals with excellent dispersibility is extremely challenging because of their high surface energy, exceedingly strong reducibility/hydrophilicity and complicated composition. Here, we demonstrate a mechanical-force-driven self-printing process that enables monodispersed (~6 nm) NaBH4 nanodots to uniformly anchor onto freshly-exfoliated graphitic nanosheets (GNs). Both mechanical-forces and borohydride interaction with GNs stimulate NaBH4 clusters intercalation/absorption into the graphite interlayers acting as a ‘pen’ for writing, which is accomplished by exfoliating GNs with the ‘printed’ borohydrides. These nano-NaBH4@GNs exhibit favorable thermodynamics (decrease in ΔH of ~45%), rapid kinetics (a greater than six-fold increase) and stable de-/re-hydrogenation that retains a high capacity (up to ~5 wt% for NaBH4) compared with those of micro-NaBH4. Our results are helpful in the scalable fabrication of zero-dimensional complex hydrides on two-dimensional supports with enhanced hydrogen storage for potential applications.

Self-Printing on Graphitic Nanosheets with Metal Borohydride Nanodots for Hydrogen Storage

PubMed Central

Li, Yongtao; Ding, Xiaoli; Zhang, Qingan

2016-01-01

Although the synthesis of borohydride nanostructures is sufficiently established for advancement of hydrogen storage, obtaining ultrasmall (sub-10 nm) metal borohydride nanocrystals with excellent dispersibility is extremely challenging because of their high surface energy, exceedingly strong reducibility/hydrophilicity and complicated composition. Here, we demonstrate a mechanical-force-driven self-printing process that enables monodispersed (~6 nm) NaBH4 nanodots to uniformly anchor onto freshly-exfoliated graphitic nanosheets (GNs). Both mechanical-forces and borohydride interaction with GNs stimulate NaBH4 clusters intercalation/absorption into the graphite interlayers acting as a ‘pen’ for writing, which is accomplished by exfoliating GNs with the ‘printed’ borohydrides. These nano-NaBH4@GNs exhibit favorable thermodynamics (decrease in ∆H of ~45%), rapid kinetics (a greater than six-fold increase) and stable de-/re-hydrogenation that retains a high capacity (up to ~5 wt% for NaBH4) compared with those of micro-NaBH4. Our results are helpful in the scalable fabrication of zero-dimensional complex hydrides on two-dimensional supports with enhanced hydrogen storage for potential applications. PMID:27484735

Real-time electrochemical LAMP: a rational comparative study of different DNA intercalating and non-intercalating redox probes.

PubMed

Martin, Alexandra; Bouffier, Laurent; Grant, Kathryn B; Limoges, Benoît; Marchal, Damien

2016-06-20

We present a comparative study of ten redox-active probes for use in real-time electrochemical loop-mediated isothermal amplification (LAMP). Our main objectives were to establish the criteria that need to be fulfilled for minimizing some of the current limitations of the technique and to provide future guidelines in the search for ideal redox reporters. To ensure a reliable comparative study, each redox probe was tested under similar conditions using the same LAMP reaction and the same entirely automatized custom-made real-time electrochemical device (designed for electrochemically monitoring in real-time and in parallel up to 48 LAMP samples). Electrochemical melt curve analyses were recorded immediately at the end of each LAMP reaction. Our results show that there are a number of intercalating and non-intercalating redox compounds suitable for real-time electrochemical LAMP and that the best candidates are those able to intercalate strongly into ds-DNA but not too much to avoid inhibition of the LAMP reaction. The strongest intercalating redox probes were finally shown to provide higher LAMP sensitivity, speed, greater signal amplitude, and cleaner-cut DNA melting curves than the non-intercalating molecules.

Formation of Reversible Solid Electrolyte Interface on Graphite Surface from Concentrated Electrolytes

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

Lu, Dongping; Tao, Jinhui; Yan, Pengfei

2017-02-10

Interfacial phenomena have always been key determinants for the performance of energy storage technologies. The solid electrolyte interfacial (SEI) layer, pervasive on the surfaces of battery electrodes for numerous chemical couples, directly affects the ion transport, charge transfer and lifespan of the entire energy system. Almost all SEI layers, however, are unstable resulting in the continuous consumption of the electrolyte. Typically, this leads to the accumulation of degradation products on/restructuring of the electrode surface and thus increased cell impedance, which largely limits the long-term operation of the electrochemical reactions. Herein, a completely new SEI formation mechanism has been discovered, inmore » which the electrolyte components reversibly self-assemble into a protective surface coating on a graphite electrode upon changing the potential. In contrast to the established wisdom regarding the necessity of employing the solvent ethylene carbonate (EC) to form a protective SEI layer on graphite, a wide range of EC-free electrolytes are demonstrated for the reversible intercalation/deintercalation of Li+ cations within a graphite lattice, thereby providing tremendous flexibility in electrolyte tailoring for battery couples. This novel finding is broadly applicable and provides guidance for how to control interfacial reactions through the relationship between ion aggregation and solvent decomposition at polarized interfaces.« less

Graphite intercalated polyaniline composite with superior anticorrosive and hydrophobic properties, as protective coating material on steel surfaces

NASA Astrophysics Data System (ADS)

Rathnayake, R. M. N. M.; Mantilaka, M. M. M. G. P. G.; Hara, Masanori; Huang, Hsin-Hui; Wijayasinghe, H. W. M. A. C.; Yoshimura, Masamichi; Pitawala, H. M. T. G. A.

2017-07-01

Solid polymer composite systems are widely being used for potential technological applications in secondary energy sources and electrochromic devices. In this study, we synthesized and characterized a composite material composed of polyaniline (PANI) and natural needle platy (NPG) vein graphite. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), micro-Raman analysis, thermogravimetric and differential thermal analysis (TGA/DTA), transmission electron microscopy (TEM) were used to study the structural and electrochemical properties of the prepared PANI/NPG graphite composite. XPS, FTIR, and micro-Raman analysis confirmed the existence of relevant functional groups and bonding in the prepared PANI/NPG composite material. The composite shows a very low corrosion rate, approximately 29 μm per year, and high hydrophobicity on steel surfaces, which helps to prevent the corrosion due to O2 penetration towards the metal surface. It indicates that the composite can be used as a high potential surface coating material to anticorrosion. The specific capacitance of PANI/NPG composite is 833.3 F g-1, which is higher than that of PANI. This synergistic electrical performance result proves the prepared PANI/NPG graphite composite as a suitable protective coating material for steel surfaces.

A Nanoporous Carbon/Exfoliated Graphite Composite For Supercapacitor Electrodes

NASA Astrophysics Data System (ADS)

Rosi, Memoria; Ekaputra, Muhamad P.; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal

2010-12-01

Nanoporous carbon was prepared from coconut shells using a simple heating method. The nanoporous carbon is subjected to different treatments: without activation, activation with polyethylene glycol (PEG), and activation with sodium hydroxide (NaOH)-PEG. The exfoliated graphite was synthesized from graphite powder oxidized with zinc acetate (ZnAc) and intercalated with polyvinyl alcohol (PVA) and NaOH. A composite was made by mixing the nanoporous carbon with NaOH-PEG activation, the exfoliated graphite and a binder of PVA solution, grinding the mixture, and annealing it using ultrasonic bath for 1 hour. All of as-synthesized materials were characterized by employing a scanning electron microscope (SEM), a MATLAB's image processing toolbox, and an x-ray diffractometer (XRD). It was confirmed that the composite is crystalline with (002) and (004) orientations. In addition, it was also found that the composite has a high surface area, a high distribution of pore sizes less than 40 nm, and a high porosity (67%). Noting that the pore sizes less than 20 nm are significant for ionic species storage and those in the range of 20 to 40 nm are very accessible for ionic clusters mobility across the pores, the composite is a promising material for the application as supercapacitor electrodes.

Synthesis and characterization of SiC based composite materials for immobilizing radioactive graphite

NASA Astrophysics Data System (ADS)

Wang, Qing; Teng, Yuancheng; Wu, Lang; Zhang, Kuibao; Zhao, Xiaofeng; Hu, Zhuang

2018-06-01

In order to immobilize high-level radioactive graphite, silicon carbide based composite materials{ (1-x) SiC· x MgAl2O4 (0.1 ≤ x≤0.4) } were fabricated by solid-state reaction at 1370 °C for 2 h in vacuum. Residual graphite and precipitated corundum were observed in the as-synthesized product, which attributed to the interface reaction of element silicon and magnesium compounds. To further understand the reasons for the presence of graphite and corundum, the effects of mole ratio of Si/C, MgAl2O4 content and non-stoichiometry of MgAl2O4 on the synthesis were investigated. To immobilize graphite better, residual graphite should be eliminated. The target product was obtained when the mole ratio of Si/C was 1.3:1, MgAl2O4 content was x = 0.2, and the mole ratio of Al to Mg in non-stoichiometric MgAl2O4 was 1.7:1. In addition, the interface reaction between magnesium compounds and silicon not graphite was displayed by conducting a series of comparative experiments. The key factor for the occurrence of interface reaction is that oxygen atom is transferred from magnesium compound to SiO gas. Infrared and Raman spectrum revealed the increased disorders of graphite after being synthesized.

Intercalation of biomolecules into NiAl-NO 3 layered double hydroxide films synthesized in situ on anodic alumina/aluminium support

NASA Astrophysics Data System (ADS)

Zhao, Hua-Zhang; Chang, Ying-Yue; Yang, Jing; Yang, Qin-Zheng

2013-03-01

Layered double hydroxide (LDH) films were synthesized in situ on anodic alumina/aluminium (AAO/Al). Glucose oxidase (GOD) and L-ascorbic acid (vitamin C, VC) were intercalated respectively into the in-situ grown LDH films by anion-exchange in aqueous solutions. Dodecylsulfate (SDS) was used to expand the lamellar structure before GOD intercalation into the LDH film. The resulting products were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). The results showed that VC and GOD were successfully intercalated into the in-situ synthesized LDH film. These biomolecules loaded LDH films could have potential applications in electrode modification, safe storage and effective delivery of bioactive compounds.

Composite electrochemical biosensors: a comparison of three different electrode matrices for the construction of amperometric tyrosinase biosensors.

PubMed

Serra, B; Jiménez, S; Mena, M L; Reviejo, A J; Pingarrón, J M

2002-03-01

A comparison of the behaviour of three different rigid composite matrices for the construction of amperometric tyrosinase biosensors, which are widely used for the detection of phenolic compounds, is reported. The composite electrode matrices were, graphite-Teflon; reticulated vitreous carbon (RVC)-epoxy resin; and graphite-ethylene/propylene/diene (EPD) terpolymer. After optimization of the experimental conditions, different aspects regarding the stability of the three composite tyrosinase electrode designs were considered and compared. A better reproducibility of the amperometric responses was found with the graphite-EPD electrodes, whereas a longer useful lifetime was observed for the graphite-Teflon electrodes. The kinetic parameters of the tyrosinase reaction were calculated for eight different phenolic compounds, as well as their corresponding calibration plots. The general trend in sensitivity was graphite-EPD>graphite-Teflon>RVC-epoxy resin. A correlation between sensitivity and the catalytic efficiency of the enzyme reaction for each phenolic substrate was found. Furthermore, differences in the sensitivity order for the phenolic compounds were observed among the three biocomposite electrodes, which suggests that the nature of the electrode matrix influences the interactions in the tyrosinase catalytic cycle.

Structural, optical, and electrical characteristics of graphene nanosheets synthesized from microwave-assisted exfoliated graphite

NASA Astrophysics Data System (ADS)

Chamoli, Pankaj; Das, Malay K.; Kar, Kamal K.

2017-11-01

In the present study, low defect density graphene nanosheets (GNs) have been synthesized via chemical reduction of exfoliated graphite (EG) in the presence of a green reducing agent, oxalic acid. EG has been synthesized via chemical intercalation of natural flake graphite followed by exfoliation through microwave irradiation at 800 W for 50 s. 50 mg/mL concentration of oxalic acid helps to extract low defect density GNs from EG. As-synthesized GNs have been characterized by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, UV-Visible spectroscopy, field emission scanning electron microscopy, and X-ray photon spectroscopy. Raman analysis confirms the removal of oxygen functional groups from EG and achieved an ID/IG ratio of ˜0.10 with low defect density (˜1.12 × 1010 cm-2). Elemental analysis supports the Raman signature of the removal of oxygen functionalities from EG, and a high C/O ratio of ˜15.97 is obtained. Further, transparent conducting films (TCFs) have been fabricated by spray coating. The optical and electrical properties of fabricated TCFs have been measured after thermal graphitization. Thermal graphitization helps to improve the optical and electrical properties of TCFs by tuning the optical bandgap in a controlled way. TCF shows best performance when the film is annealed at 900 °C for 1 h in vacuum. It shows a sheet resistance of ˜1.10 kΩ/◻ and a transmittance of ˜71.56% at 550 nm.

One-step synthesis of layered yttrium hydroxides in immiscible liquid-liquid systems: Intercalation of sterically-bulky hydrophobic organic anions and doping of europium ions

NASA Astrophysics Data System (ADS)

Watanabe, Mebae; Fujihara, Shinobu

2014-02-01

Inorganic-organic layered rare-earth compounds were synthesized on the basis of a biphasic liquid-liquid system in one pot. Layered yttrium hydroxides (LYHs) were chosen as a host material for the intercalation of hydrophobic organic guest anions such as benzoate, sebacate, or laurate. In a typical synthesis, an organic phase dissolving carboxylic acid was placed in contact with an equal amount of an aqueous phase dissolving yttrium nitrate n-hydrate and urea. At elevated temperatures up to 80 °C, urea was hydrolyzed to release hydroxyl anions which were used to form yttrium hydroxide layers. LYHs were then precipitated with the intercalation of carboxylate anions delivered from the organic phase under the distribution law. The structure and the morphology of the LYHs could be modulated by the intercalated anions. Doped with Eu3+ ions, the LYHs exhibited red photoluminescence which was enhanced by the intercalated anions due to the antenna effect.

First-principles study of amorphous carbon: a promising candidate for Na-ion batteries

NASA Astrophysics Data System (ADS)

Kotsis, Konstantinos; Legrain, Fleur; Manzhos, Sergei

2015-03-01

The perspective of a widespread use of clean but intermittent sources of electricity (wind and solar) as well as that of hybrid electric vehicles calls for alternatives to Li-ion batteries as Li resources are limited. Na being abundant, cheap, and a relatively light and small atom, Na-ion batteries have attracted a lot of interest the past few years. However, while most of the Na-ion batteries studies focus on the positive electrode, the negative electrode remains little investigated and an efficient anode providing all a good capacity, a high cycle life, and a descent rate of charge/discharge, is still not available. The efficient electrode materials for Li, in particular diamond Si and graphite C, have been shown to not allow the intercalation of Na [1, 2]. Computational studies report positive intercalation energies [3, 4] and therefore suggest that the insertion of Na into the crystalline framework (C and Si) is thermodynamically not favored: Na atoms prefer to gather into Na clusters rather than to intercalate into the crystalline phase. Amorphization of Si was found to be a valid strategy to improve the interaction between Si and Na [3]. We investigate here the effects of amorphization of C on its storage properties vis-à-vis Na (as well as Li for reference).

Apparatus for Sizing and Rewinding Graphite Fibers

NASA Technical Reports Server (NTRS)

Wilson, M. L.; Stanfield, C. E.

1986-01-01

Equipment ideally suited for research and development of new sizing solutions. Designed expecially for applying thermoplastic sizing solutions to graphite tow consisting of 3,000 to 12,000 filaments per tow, but accommodates other solutions, filament counts, and materials other than graphite. Closed system containing highly volatile methylene chloride vapors. Also ventilation system directly over resin reservoir. Concept used to apply sizing compounds on fiber tows or yarn-type reinforcement materials used in composite technology. Sizing solutions consist of compounds compatible with thermosets as well as thermoplastics.

A green method of graphene preparation in an alkaline environment.

PubMed

Štengl, Václav; Henych, Jiří; Bludská, Jana; Ecorchard, Petra; Kormunda, Martin

2015-05-01

We present a new, simple, quick and ecologically friendly method of exfoliating graphite to produce graphene. The method is based on the intercalation of a permanganate M2MnO4 (M=K, Na, Li), which is formed by the reaction of a manganate MMnO4 with an alkali metal hydroxide MOH. The quality of exfoliation and the morphology were determined using X-ray photoelectron spectroscopy, X-ray diffraction and microscopic techniques, including transmission electron microscopy and atomic force microscopy. We observed that a stable graphene suspension could be prepared under strongly alkaline conditions in the presence of permanganate and ultrasound assistance. The use of only an alkaline environment for the direct preparation of graphene from graphite structures has not been previously described or applied. It was found that such a method of preparation leads to surprisingly high yields and a stable product for hydrophilic graphene applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of heat treatment on CO2 adsorption of KOH-activated graphite nanofibers.

PubMed

Meng, Long-Yue; Park, Soo-Jin

2010-12-15

In this work, graphite nanofibers (GNFs) were successfully expanded intercalating KOH followed by heat treatment in the temperature range of 700-1000 °C. The aim was to improve the CO(2) adsorption capacity of the GNFs by increasing the porosity of GNFs. The effects of heat treatment on the pore structures of GNFs were investigated by N(2) full isotherms, XRD, SEM, and TEM. The CO(2) adsorption capacity was measured by CO(2) isothermal adsorption at 25 °C and 1 atm. From the results, it was found that the activation temperature had a major influence on CO(2) adsorption capacity and textural properties of GNFs. The specific surface area, total pore volume, and mesopore volume of the GNFs increased after heat treatment. The CO(2) adsorption isotherms showed that G-900 exhibited the best CO(2) adsorption capacity with 59.2 mg/g. Copyright © 2010 Elsevier Inc. All rights reserved.

Plasma synthesis of lithium based intercalation powders for solid polymer electrolyte batteries

DOEpatents

Kong, Peter C [Idaho Falls, ID; Pink, Robert J [Pocatello, ID; Nelson, Lee O [Idaho Falls, ID

2005-01-04

The invention relates to a process for preparing lithium intercalation compounds by plasma reaction comprising the steps of: forming a feed solution by mixing lithium nitrate or lithium hydroxide or lithium oxide and the required metal nitrate or metal hydroxide or metal oxide and between 10-50% alcohol by weight; mixing the feed solution with O.sub.2 gas wherein the O.sub.2 gas atomizes the feed solution into fine reactant droplets, inserting the atomized feed solution into a plasma reactor to form an intercalation powder; and if desired, heating the resulting powder to from a very pure single phase product.

Investigation of colloidal graphite as a matrix for matrix-assisted laser desorption/ionisation mass spectrometry of low molecular weight analytes.

PubMed

Warren, Alexander D; Conway, Ulric; Arthur, Christopher J; Gates, Paul J

2016-07-01

The analysis of low molecular weight compounds by matrix-assisted laser desorption/ionisation mass spectrometry is problematic due to the interference and suppression of analyte ionisation by the matrices typically employed - which are themselves low molecular weight compounds. The application of colloidal graphite is demonstrated here as an easy to use matrix that can promote the ionisation of a wide range of analytes including low molecular weight organic compounds, complex natural products and inorganic complexes. Analyte ionisation with colloidal graphite is compared with traditional organic matrices along with various other sources of graphite (e.g. graphite rods and charcoal pencils). Factors such as ease of application, spectra reproducibility, spot longevity, spot-to-spot reproducibility and spot homogeneity (through single spot imaging) are explored. For some analytes, considerable matrix suppression effects are observed resulting in spectra completely devoid of matrix ions. We also report the observation of radical molecular ions [M(-●) ] in the negative ion mode, particularly with some aromatic analytes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

First-principles theory of cation- and intercalation-ordering in Li_xCoO_2

NASA Astrophysics Data System (ADS)

Wolverton, C.; Zunger, Alex

1998-03-01

Using a combination of first-principles total energies, a cluster expansion technique, and Monte Carlo simulations, we present a first-principles theory which can predict both cation- and intercalation-ordering patterns at both zero and finite temperatures, and can provide first-principles predictions of battery voltages of Li_xCoO_2/Li cells. The classes of ordering problems that we study are the following: (i) The LiMO2 oxides (M=3d metal) form a series of structures based on an octahedrally-coordinated network with anions (O) on one fcc sublattice and cations (Li and M) on the other, leading to Li/Co ordering in LiCoO2 (x=1). We find the ground state is the CuPt or (111)-layered cation arrangment, in agreement with the observed structure. (ii) In battery applications, Li is (de)intercalated from the compound, creating a vacancy (denoted Box) that can be positioned in different lattice locations; Thus, Box/Co ordering in BoxCoO2 (x=0) is also of interest. We find the ground state for BoxCoO2 is also a (111)-layered structure, although a different stacking sequence (AAA) of close-packed layers is preferred. (iii) The vacancies left behind by Li extraction can form ordered vacancy compounds in partially de-lithiated Li_xCoO_2, leading to a Box/Li ordering problem (0<=x<=1). Our calculations agree with the observed voltage profiles in these systems, and predict the existence of new intercalation-ordered compounds. Supported by BES/OER/DMS under contract DE-AC36-83CH10093.

Superconductivity at 7.4 K in few layer graphene by Li-intercalation.

PubMed

Tiwari, Anand P; Shin, Soohyeon; Hwang, Eunhee; Jung, Soon-Gil; Park, Tuson; Lee, Hyoyoung

2017-11-08

Superconductivity in graphene has been highly sought after for its promise in various device applications and for general scientific interest. Ironically, the simple electronic structure of graphene, which is responsible for novel quantum phenomena, hinders the emergence of superconductivity. Theory predicts that doping the surface of the graphene effectively alters the electronic structure, thus promoting propensity towards Cooper pair instability (Profeta et al (2012) Nat. Phys. 8 131-4; Nandkishore et al (2012) Nat. Phys. 8 158-63) [1, 2]. Here we report the emergence of superconductivity at 7.4 K in Li-intercalated few-layer-graphene (FLG). The absence of superconductivity in 3D Li-doped graphite underlines that superconductivity in Li-FLG arises from the novel electronic properties of the 2D graphene layer. These results are expected to guide future research on graphene-based superconductivity, both in theory and experiments. In addition, easy control of the Li-doping process holds promise for various device applications.

Building one-dimensional oxide nanostructure arrays on conductive metal substrates for lithium-ion battery anodes.

PubMed

Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang

2011-01-01

Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized alumina membrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.

Building one-dimensional oxidenanostructure arrays on conductive metal substrates for lithium-ion battery anodes

NASA Astrophysics Data System (ADS)

Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang

2011-01-01

Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized aluminamembrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.

Exfoliation of non-oxidized graphene flakes for scalable conductive film.

PubMed

Park, Kwang Hyun; Kim, Bo Hyun; Song, Sung Ho; Kwon, Jiyoung; Kong, Byung Seon; Kang, Kisuk; Jeon, Seokwoo

2012-06-13

The increasing demand for graphene has required a new route for its mass production without causing extreme damages. Here we demonstrate a simple and cost-effective intercalation based exfoliation method for preparing high quality graphene flakes, which form a stable dispersion in organic solvents without any functionalization and surfactant. Successful intercalation of alkali metal between graphite interlayers through liquid-state diffusion from ternary KCl-NaCl-ZnCl(2) eutectic system is confirmed by X-ray diffraction and X-ray photoelectric spectroscopy. Chemical composition and morphology analyses prove that the graphene flakes preserve their intrinsic properties without any degradation. The graphene flakes remain dispersed in a mixture of pyridine and salts for more than 6 months. We apply these results to produce transparent conducting (∼930 Ω/□ at ∼75% transmission) graphene films using the modified Langmuir-Blodgett method. The overall results suggest that our method can be a scalable (>1 g/batch) and economical route for the synthesis of nonoxidized graphene flakes.

USE OF GRANULAR GRAPHITE FOR ELECTROLYTIC DECHLORINATION OF TRICHLOROETHYLENE

EPA Science Inventory

Granular graphite is a potential electrode material for the electrochemical remediation of refractory chlorinated organic compounds such as trichloroethylene (TCE). However, the use of granular graphite can complicate the experimental results. On one hand, up to 99% of TCE was re...

Ionic Graphitization of Ultrathin Films of Ionic Compounds.

PubMed

Kvashnin, A G; Pashkin, E Y; Yakobson, B I; Sorokin, P B

2016-07-21

On the basis of ab initio density functional calculations, we performed a comprehensive investigation of the general graphitization tendency in rocksalt-type structures. In this paper, we determine the critical slab thickness for a range of ionic cubic crystal systems, below which a spontaneous conversion from a cubic to a layered graphitic-like structure occurs. This conversion is driven by surface energy reduction. Using only fundamental parameters of the compounds such as the Allen electronegativity and ionic radius of the metal atom, we also develop an analytical relation to estimate the critical number of layers.

Li Storage of Calcium Niobates for Lithium Ion Batteries.

PubMed

Yim, Haena; Yu, Seung-Ho; Yoo, So Yeon; Sung, Yung-Eun; Choi, Ji-Won

2015-10-01

New types of niobates negative electrode were studied for using in lithium-ion batteries in order to alternate metallic lithium anodes. The potassium intercalated compound KCa2Nb3O10 and proton intercalated compound HCa2Nb3O10 were studied, and the electrochemical results showed a reversible cyclic voltammetry profile with acceptable discharge capacity. The as-prepared KCa2Nb3O10 negative electrode had a low discharge capacity caused by high overpotential, but the reversible intercalation and deintercalation reaction of lithium ions was activated after exchanging H+ ions for intercalated K+ ions. The initial discharge capacity of HCa2Nb3O10 was 54.2 mAh/g with 92.1% of coulombic efficiency, compared with 10.4 mAh/g with 70.2% of coulombic efficiency for KCa2Nb3O10 at 1 C rate. The improved electrochemical performance of the HCa2Nb3O10 was related to the lower bonding energy between proton cation and perovskite layer, which facilitate Li+ ions intercalating into the cation site, unlike potassium cation and perovskite layer. Also, this negative material can be easily exfoliated to Ca2Nb3O10 layer by using cation exchange process. Then, obtained two-dimensional nanosheets layer, which recently expected to be an advanced electrode material because of its flexibility, chemical stable, and thin film fabricable, can allow Li+ ions to diffuse between the each perovskite layer. Therefore, this new type layered perovskite niobates can be used not only bulk-type lithium ion batteries but also thin film batteries as a negative material.

In Situ Raman Microscopy of a Single Graphite Microflake Electrode in a Li(+)-containing Electrolyte

NASA Technical Reports Server (NTRS)

Shi, Qing-Fang; Dokko, Kaoru; Scherson, Daniel A.

2003-01-01

Highly detailed Raman spectra from a single KS-44 graphite microflake electrode as a function of the applied potential have been collected in situ using a Raman microscope and a sealed spectroelectrochemical cell isolated from the laboratory environment. Correlations were found between the Raman spectral features and the various Li(+) intercalation stages while recording in real time Raman spectra during a linear potential scan from 0.7 down ca. 0.0V vs Li/Li(+) at a rate of 0.1 mV/s in a 1M LiClO4 solution in a 1:l (by volume) ethylene carbonate (EC):diethyl carbonate (DEC) mixture. In particular, clearly defined isosbestic points were observed for data collected in the potential range where the transition between dilute phase 1 and phase 4 of lithiated graphite is known to occur, i.e. 0.157 < E < 0.215 vs Li/Li(+). Statistical analysis of the spectroscopic data within this region made it possible to determine independently the fraction of each of the two phases present as a function of potential without relying on coulometric information and then predict, based on the proposed stoichiometry for the transition, a spectrally-derived voltammetric feature.

Process for producing advanced ceramics

DOEpatents

Kwong, Kyei-Sing

1996-01-01

A process for the synthesis of homogeneous advanced ceramics such as SiC+AlN, SiAlON, SiC+Al.sub.2 O.sub.3, and Si.sub.3 N.sub.4 +AlN from natural clays such as kaolin, halloysite and montmorillonite by an intercalation and heat treatment method. Included are the steps of refining clays, intercalating organic compounds into the layered structure of clays, drying the intercalated mixture, firing the treated atmospheres and grinding the loosely agglomerated structure. Advanced ceramics produced by this procedure have the advantages of homogeneity, cost effectiveness, simplicity of manufacture, ease of grind and a short process time. Advanced ceramics produced by this process can be used for refractory, wear part and structure ceramics.

The Electrical and Thermal Conductivity of Woven Pristine and Intercalated Graphite Fiber-Polymer Composites

NASA Technical Reports Server (NTRS)

Gaier, James R.; Vandenburg, Yvonne Yoder; Berkebile, Steven; Stueben, Heather; Balagadde, Frederick

2002-01-01

A series of woven fabric laminar composite plates and narrow strips were fabricated from a variety of pitch-based pristine and bromine intercalated graphite fibers in an attempt to determine the influence of the weave on the electrical and thermal conduction. It was found generally that these materials can be treated as if they are homogeneous plates. The rule of mixtures describes the resistivity of the composite fairly well if it is realized that only the component of the fibers normal to the equipotential surface will conduct current. When the composite is narrow with respect to the fiber weave, however, there is a marked angular dependence of the resistance which was well modeled by assuming that the current follows only along the fibers (and not across them in a transverse direction), and that the contact resistance among the fibers in the composite is negligible. The thermal conductivity of composites made from less conductive fibers more closely followed the rule of mixtures than that of the high conductivity fibers, though this is thought to be an artifact of the measurement technique. Electrical and thermal anisotropy could be induced in a particular region of the structure by weaving together high and low conductivity fibers in different directions, though this must be done throughout all of the layers of the structure as interlaminar conduction precludes having only the top layer carry the anisotropy. The anisotropy in the thermal conductivity is considerably less than either that predicted by the rule of mixtures or the electrical resistivity.

Thermal energy harvesting and solar energy conversion utilizing carbon-based nanomaterials

NASA Astrophysics Data System (ADS)

McCarthy, Patrick T.

This dissertation provides details of carbon-based nanomaterial fabrication for applications in energy harvesting and generation. As energy demands increase, and concerns about mankind's environmental impact increase, alternative methods of generating energy will be widely researched. Carbon-based nanomaterials may be effective in such applications as their fabrication is often inexpensive and they have highly desirable electrical, mechanical, and thermal properties. Synthesis and characterization of carbon nanotube thermal interfaces on gadolinium foils is described herein. Total thermal interface resistances of carbon nanotube coated gadolinium were measured using a one-dimensional reference calorimeter technique, and the effect of hydrogen embrittlement on the magnetic properties of gadolinium foils is discussed. The samples generated in this study were consistently measured with reduced total thermal interface resistances of 55-70% compared to bare gadolinium. Characterization of gadolinium foils in a cooling device called a magneto thermoelectric generator was also performed. A gadolinium shuttle drives the device as it transitions between ferromagnetic and paramagnetic states. Reduced interface resistances from the carbon nanotube arrays led to increased shuttle frequency and effective heat transfer coefficients. Detailed theoretical derivations for electron emission during thermal and photo-excitation are provided for both three-dimensional and two-dimensional materials. The derived theories were fitted to experimental data from variable temperature photoemission studies of potassium-intercalated graphitic nanopetals. A work function reduction from approximately 4.5 eV to 2 -- 3 eV resulted from potassium intercalation and adsorption. While changes in the electron energy distribution shape and intensity were significant within 310 -- 680 K, potassium-intercalated graphitic petals demonstrate very high thermal stability after heating to nearly 1000 K. Boron nitride modification of the nanopetals was performed in an effort to minimize deintercalation of potassium from the nanopetal lattice and while multiple work functions were present within the electron energy distribution, massive reductions in emission intensity took place above 580 K. Finally, a device for measuring the current density during photoemission was also developed and photoemission induced by a solar simulator at room temperature produced currents on the order of 1 nA/cm 2 resulting in a quantum efficiency of approximately 8.0x10 --8 electrons emitted per photon of illumination.

METHOD OF COATING GRAPHITE WITH STABLE METAL CARBIDES AND NITRIDES

DOEpatents

Gurinsky, D.H.

1959-10-27

A method is presented for forming protective stable nitride and carbide compounds on the surface of graphite. This is accomplished by contacting the graphite surface with a fused heavy liquid metal such as bismuth or leadbismuth containing zirconium, titanium, and hafnium dissolved or finely dispersed therein to form a carbide and nitride of at least one of the dissolved metals on the graphite surface.

Density-functional studies of tungsten trioxide, tungsten bronzes, and related systems

NASA Astrophysics Data System (ADS)

Ingham, B.; Hendy, S. C.; Chong, S. V.; Tallon, J. L.

2005-08-01

Tungsten trioxide adopts a variety of structures which can be intercalated with charged species to alter the electronic properties, thus forming “tungsten bronzes.” Similar effects are observed upon removing oxygen from WO3 . We present a computational study of cubic and hexagonal alkali bronzes and examine the effects on cell size and band structure as the size of the intercalated ion is increased. With the exception of hydrogen (which is predicted to be unstable as an intercalate), the behavior of the bronzes are relatively consistent. NaWO3 is the most stable of the cubic systems, although in the hexagonal system the larger ions are more stable. The band structures are identical, with the intercalated atom donating its single electron to the tungsten 5d valence band. A study of fractional doping in the NaxWO3 system (0⩽x⩽1) showed a linear variation in cell parameter and a systematic shift in the Fermi level into the conduction band. In the oxygen-deficient WO3-x system the Fermi level undergoes a sudden jump into the conduction band at around x=0.2 . Lastly, three compounds of a layered WO4•α,ω -diaminoalkane hybrid series were studied and found to be insulating, with features in the band structure similar to those of the parent WO3 compound that relate well to experimental UV-visible spectroscopy results.

Effect of hydrotalcite-like compounds on the aqueous solubility of some poorly water-soluble drugs.

PubMed

Ambrogi, Valeria; Fardella, Giuseppe; Grandolini, Giuliano; Nocchetti, Morena; Perioli, Luana

2003-07-01

A new approach of improving drug dissolution properties is described. This method exploits the property of a carrier owing to the hydrotalcite-type anionic clays (HTlc). HTlc is an inorganic layered solid that lodges anionic compounds among its layers. As HTlc dissolves at acidic pH values (pH < 4), the anions intercalated among the layers are promptly released in the medium. In this article some nonsteroidal antiinflammatory drugs were chosen as models of poorly water-soluble drugs. They were intercalated in HTlc and solubility measurements in acidic medium were performed. A remarkable improvement of drug solubility was observed especially in the case of indomethacin. Copyright 2003 Wiley-Liss, Inc. and the American Pharmacists Association

Structure and dynamics in low-dimensional guest host solids

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

Fischer, J.

1991-04-01

This progress report presents results from work during the period of June 1, 1990 through May 31st, 1991. Topics discussed include instrumentation, publications, and personnel. Work areas discussed include: pressure-induced transitions in Li- and Ag-TiS{sub 2}, hyper-dense superconducting GIC's, temperature-dependent x-ray structure of (CH){sub x} and (CH){sub 2{sup x}}:analogies to rotator phases in short-chain alkanes, trans-(CH){sub x} at high'' pressure, broken symmetries'' in polymer intercalation channel lattices, high-resolution study of conductivity and cell potential vs. concentration in K-doped (CH){sub x}, new'' doped (CH){sub x} phases: ternary compounds and amorphous'' intercalation compounds, and vibrational density states from inelastic neutron scattering. (JF).

4-Vinyl-1,3-Dioxolane-2-One as an Additive for Li-Ion Cells

NASA Technical Reports Server (NTRS)

Smart, Marshall; Bugga, Ratnakumar

2006-01-01

Electrolyte additive 4-vinyl-1,3-dioxolane-2-one has been found to be promising for rechargeable lithium-ion electrochemical cells. This and other additives, along with advanced electrolytes comprising solutions of LiPF6 in various mixtures of carbonate solvents, have been investigated in a continuing effort to improve the performances of rechargeable lithium-ion electrochemical cells, especially at low temperatures. In contrast to work by other researchers who have investigated the use of this additive to improve the high-temperature resilience of Li-ion cells, the current work involves the incorporation of 4-vinyl-1,3-dioxolane-2-one into quaternary carbonate electrolyte mixtures, previously optimized for low-temperature applications, resulting in improved low-temperature performance. The benefit afforded by 4-vinyl-1,3- dioxolane-2-one can be better understood in the light of relevant information from a number of prior NASA Tech Briefs articles about electrolytes and additives for such cells. To recapitulate: The loss of performance with decreasing temperature is attributable largely to a decrease of ionic conductivity and the increase in viscosity of the electrolyte. What is needed to extend the lower limit of operating temperature is a stable electrolyte solution with relatively small lowtemperature viscosity, a large electric permittivity, adequate coordination behavior, and appropriate ranges of solubilities of liquid and salt constituents. Whether the anode is made of graphitic or non-graphitic carbon, a film on the surface of the anode acts as a solid/electrolyte interface (SEI), the nature of which is critical to low-temperature performance. Desirably, the surface film should exert a chemically protective (passivating) effect on both the anode and the electrolyte, yet should remain conductive to lithium ions to facilitate intercalation and de-intercalation of the ions into and out of the carbon during discharging and charging, respectively. The additives investigated previously include alkyl pyrocarbonates. Those additives help to improve low-temperature performances by giving rise to the formation of SEIs having desired properties. The formation of the SEIs is believed to be facilitated by products (e.g., CO2) of the decomposition of these additives. These decomposition products are believed to react to form Li2CO3-based films on the carbon electrodes. The present additive, 4-vinyl-1,3-dioxolane-2-one, also helps to improve lowtemperature performance by contributing to the formation of SEIs having desired properties, but probably in a different manner: It is believed that, as part of the decomposition process, the compound polymerizes on the surfaces of carbon electrodes.

Targeting radiosensitizers to DNA by attachment of an intercalating group: Nitroimidazole-linked phenanthridines

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

Cowan, D.S.; Panicucci, R.; McClelland, R.A.

The nitroimidazole-linked phenanthridine series of compounds (NLP-1, 2, and 3) were synthesized under the assumption that it should be possible to enhance the molar efficiency of 2-nitroimidazoles as hypoxic cell radiosensitizers and cytotoxins by targeting them to their likely site of action, DNA. The targeting group chosen was the phenanthridine moiety, the major component of the classical DNA intercalating compound, ethidium bromide. The sole difference between the compounds is the length of the hydrocarbon chain linking the nitroimidazole to the phenanthridine. The phenanthridine group with a three-carbon side chain, P-1, was also synthesized to allow studies on the effect ofmore » the targeting group by itself. The ability of the compounds to bind to DNA is inversely proportional to their linker chain length with binding constant values ranging from approximately 1 {times} 10(5) mol-1 for NLP-2 to 6 {times} 10(5) mol-1 for NLP-3. The NLP compounds show selective toxicity to hypoxic cells at 37 degrees C at external drug concentrations 10-40 times lower than would be required for untargeted 2-nitroimidazoles such as misonidazole in vitro. Toxicity to both hypoxic and aerobic cells is dependent on the linker chain: the shorter the chain, the greater the toxicity. In addition, the NLP compounds radiosensitize hypoxic cells at external drug concentrations as low as 0.05 mM with almost the full oxygen effect being observed at a concentration of 0.5 mM. These concentrations are 10-100 times lower than would be required for similar radiosensitization using misonidazole. Radiosensitizing ability is independent of linker chain length. The present compounds represent prototypes for further studies of the efficacy and mechanism of action of 2-nitroimidazoles targeted to DNA by linkage to an intercalating group.« less

Ab initio simulation of changes in geometry, electronic structure, and Gibbs free energy caused by dehydration of hydrotalcites containing Cl⁻ and CO₃²⁻ counteranions.

PubMed

Costa, Deyse G; Rocha, Alexandre B; Souza, Wladmir F; Chiaro, Sandra Shirley X; Leitão, Alexandre A

2011-04-07

This ab initio study was performed to better understand the correlation between intercalated water molecules and layered double hydroxides (LDH), as well as the changes that occur by the dehydration process of Zn-Al hydrotalcite-like compounds containing Cl⁻ and CO₃²⁻ counterions. We have verified that the strong interaction among intercalated water molecules, cointercalated anions, and OH groups from hydroxyl layers is reflected in the thermal stability of these compounds. The Zn(2/3)Al(1/3)(OH)₂Cl(1/3)·2/3H₂O hydrotalcite loses all the intercalated water molecules around 125 °C, while the Zn(2/3)Al(1/3)(OH)₂(CO₃)(1/6)·4/6H₂O compound dehydrates at about 175 °C. These values are in good agreement with experimental data. The interlayer interactions were discussed on the basis of electron density difference analyses. Our calculation shows that the electron density in the interlayer region decreases during the dehydration process, inducing the migration of the Cl⁻ anion and the displacement of the hydroxyl layer from adjacent layers. Changes in these compound structures occur to recover part of the hydrogen bonds broken due to the removal of water molecules. It was observed that the chloride ion had initially a lower Löwdin charge (Cl(-0.43)), which has increased its absolute value (Cl(-0.58)) after the water molecules removal, while the charges on carbonate ions remain invariant, leading to the conclusion that the Cl⁻ anion can be more influenced by the amount of water molecules in the interlayer space than the CO₃²⁻ anion in hydrotalcite-like compounds.

Alkali metal intercalated fullerene-like MS(2) (M = W, Mo) nanoparticles and their properties.

PubMed

Zak, Alla; Feldman, Yishay; Lyakhovitskaya, Vera; Leitus, Gregory; Popovitz-Biro, Ronit; Wachtel, Ellen; Cohen, Hagai; Reich, Shimon; Tenne, Reshef

2002-05-01

Layered metal disulfides-MS(2) (M = Mo, W) in the form of fullerene-like nanoparticles and in the form of platelets (crystallites of the 2H polytype) have been intercalated by exposure to alkali metal (potassium and sodium) vapor using a two-zone transport method. The composition of the intercalated systems was established using X-ray energy dispersive spectrometer and X-ray photoelectron spectroscopy (XPS). The alkali metal concentration in the host lattice was found to depend on the kind of sample and the experimental conditions. Furthermore, an inhomogeneity of the intercalated samples was observed. The product consisted of both nonintercalated and intercalated phases. X-ray diffraction analysis and transmission electron microscopy of the samples, which were not exposed to the ambient atmosphere, showed that they suffered little change in their lattice parameters. On the other hand, after exposure to ambient atmosphere, substantial increase in the interplanar spacing (3-5 A) was observed for the intercalated phases. Insertion of one to two water molecules per intercalated metal atom was suggested as a possible explanation for this large expansion along the c-axis. Deintercalation of the hydrated alkali atoms and restacking of the MS(2) layers was observed in all the samples after prolonged exposure to the atmosphere. Electric field induced deintercalation of the alkali metal atoms from the host lattice was also observed by means of the XPS technique. Magnetic moment measurements for all the samples indicate a diamagnetic to paramagnetic transition after intercalation. Measurements of the transport properties reveal a semiconductor to metal transition for the heavily K intercalated 2H-MoS(2). Other samples show several orders of magnitude decrease in resistivity and two- to five-fold decrease in activation energies upon intercalation. These modifications are believed to occur via charge transfer from the alkali metal to the conduction band of the host lattice. Recovery of the pristine compound properties (diamagnetism and semiconductivity) was observed as a result of deintercalation.

Eco-friendly preparation of large-sized graphene via short-circuit discharge of lithium primary battery.

PubMed

Kang, Shaohong; Yu, Tao; Liu, Tingting; Guan, Shiyou

2018-02-15

We proposed a large-sized graphene preparation method by short-circuit discharge of the lithium-graphite primary battery for the first time. LiC x is obtained through lithium ions intercalation into graphite cathode in the above primary battery. Graphene was acquired by chemical reaction between LiC x and stripper agents with dispersion under sonication conditions. The gained graphene is characterized by Raman spectrum, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Atomic force microscope (AFM) and Scanning electron microscopy (SEM). The results indicate that the as-prepared graphene has a large size and few defects, and it is monolayer or less than three layers. The quality of graphene is significant improved compared to the reported electrochemical methods. The yield of graphene can reach 8.76% when the ratio of the H 2 O and NMP is 3:7. This method provides a potential solution for the recycling of waste lithium ion batteries. Copyright © 2017 Elsevier Inc. All rights reserved.

Purification Procedures for Single-Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Gorelik, Olga P.; Nikolaev, Pavel; Arepalli, Sivaram

2001-01-01

This report summarizes the comparison of a variety of procedures used to purify carbon nanotubes. Carbon nanotube material is produced by the arc process and laser oven process. Most of the procedures are tested using laser-grown, single-wall nanotube (SWNT) material. The material is characterized at each step of the purification procedures by using different techniques including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Raman, X-ray diffractometry (XRD), thermogravimetric analysis (TGA), nuclear magnetic resonance (NMR), and high-performance liquid chromatography (HPLC). The identified impurities are amorphous and graphitic carbon, catalyst particle aggregates, fullerenes, and hydrocarbons. Solvent extraction and low-temperature annealing are used to reduce the amount of volatile hydrocarbons and dissolve fullerenes. Metal catalysts and amorphous as well as graphitic carbon are oxidized by reflux in acids including HCl, HNO3 and HF and other oxidizers such as H2O2. High-temperature annealing in vacuum and in inert atmosphere helps to improve the quality of SWNTs by increasing crystallinity and reducing intercalation.

Thermodynamic Simulation of Equilibrium Composition of Reaction Products at Dehydration of a Technological Channel in a Uranium-Graphite Reactor

NASA Astrophysics Data System (ADS)

Pavliuk, A. O.; Zagumennov, V. S.; Kotlyarevskiy, S. G.; Bespala, E. V.

2018-01-01

The problems of accumulation of nuclear fuel spills in the graphite stack in the course of operation of uranium-graphite nuclear reactors are considered. The results of thermodynamic analysis of the processes in the graphite stack at dehydration of a technological channel, fuel element shell unsealing and migration of fission products, and activation of stable nuclides in structural elements of the reactor and actinides inside the graphite moderator are given. The main chemical reactions and compounds that are produced in these modes in the reactor channel during its operation and that may be hazardous after its shutdown and decommissioning are presented. Thermodynamic simulation of the equilibrium composition is performed using the specialized code TERRA. The results of thermodynamic simulation of the equilibrium composition in different cases of technological channel dehydration in the course of the reactor operation show that, if the temperature inside the active core of the nuclear reactor increases to the melting temperature of the fuel element, oxides and carbides of nuclear fuel are produced. The mathematical model of the nonstationary heat transfer in a graphite stack of a uranium-graphite reactor in the case of the technological channel dehydration is presented. The results of calculated temperature evolution at the center of the fuel element, the replaceable graphite element, the air gap, and in the surface layer of the block graphite are given. The numerical results show that, in the case of dehydration of the technological channel in the uranium-graphite reactor with metallic uranium, the main reaction product is uranium dioxide UO2 in the condensed phase. Low probability of production of pyrophoric uranium compounds (UH3) in the graphite stack is proven, which allows one to disassemble the graphite stack without the risk of spontaneous graphite ignition in the course of decommissioning of the uranium-graphite nuclear reactor.

Effect of Acetylene Black Content to Half Cells Li-ion Battery Performance Based on Li4Ti5O12 using Li2CO3 as Lithium Ion Source with Hydrothermal Mechanochemical Process

NASA Astrophysics Data System (ADS)

Priyono, B.; Faizah; Syahrial, A. Z.; Subhan, A.

2017-07-01

Lithium titanate (Li4Ti5O12)/LTO is a promising candidate to be used as anode electrode in Li-ion battery, to replace graphite in Li-ion battery application. Crystal structure of lithium titanate/LTO is more stable or undergoes less strain than graphite during intercalation and de-intercalation process Li+ ions. However, although lithium titanate has good stability, the material has low electrical conductivity and lithium ion diffusion. The purpose of this research is to synthesis the spinel LTO using combinated hydrothermal and mechanochemical processes from xerogel TiO2. Then, to increase the conductivity, in the half-cell battery assembly process it was added acetylene black conductive (AB) additive with various from 10%, to 15% in wt. The LTO obtained were characterized using scanning electron microscope (SEM), X-Ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET). The XRD showed a rutile as minor phase, while SEM showed homogeneous distribution of particle with an average particle size of 0.35 μm. The BET showed that the surface area of LTO formed is 2.26 m2/g. The assembled coin half cells used this Li4Ti5O12 as a cathode and lithium metal foil as the anode were tested using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and charge discharge (CD). The conductivity value obtained from EIS corresponds to the contents of AB. Meanwhile, the CV and CD testing showed that higher percentage of AB causing the decrease of battery specific capacity. The highest specific capacity at the rate of 10C is obtained at the mixture of 10wt% AB with the value of 40.91 mAh/g.

Studies of hexafluorophosphate, tetrafluoroborate, and perchlorate electro-intercalation into graphitic carbon

NASA Astrophysics Data System (ADS)

Seel, Jennifer Ann

There has been some interest in using carbon materials as both working electrodes in electrochemical cells and rechargeable batteries [1--6]. This would result in the intercalation of not only of lithium ions into one carbon electrode but the anion component of the lithium salt, such as PF 6-, into the other carbon electrode. The intercalation of the anion component of the salt into carbon electrodes has not been studied extensively and it is not completely understood. The work presented here will expand on this rarely touched subject through electrochemical cycling as well as in-situ and ex-situ X-ray diffraction experiments. The anions that will be studied are: PF6- , BF4- and ClO4 -. It will be shown that anion intercalation occurs for various types of soft carbons and that the process can be greatly affected by the amount of turbostratic disorder present in the carbon material as well as by the specific anion used. It was discovered that using ethyl methyl sulfone, EMS, as the solvent component of the electrolyte resulted in more stable electrochemical cells than ethylene carbonate/diethyl carbonate, a more common solvent, at the high potentials required for anion intercalation. It was also discovered that PF 6 and BF4 formed staged phases during electrochemical cycling whereas ClO4 did not. The amount of disorder present in the carbon electrode did affect the intercalation of the anion. The samples with a greater amount of disorder present had a larger amount of capacity loss between charge and discharge capacities. It was also found that purer and more distinct staged phases occurred in the more ordered carbon samples. The turbostratically disordered carbon layers may rotate to accommodate PF6 and therefore become slightly more ordered. X-ray diffraction evidence suggests that intercalated PF6 molecules may be free-rotating between the carbon layers. However, the orientation of BF4 molecules between the carbon layers could not be determined. There may also be some co-intercalation of the solvent, mainly with ClO 4 and to a lesser extent BF4 and PF6. It is thought that a large amount of solvent co-intercalation occurs with ClO4 and this is the most probable reason why staged phases were not observed. An unfortunate aspect of this study is that dual carbon cells are not at all viable as commercial cells. The energy densities of dual carbon cells are much lower than the currently available lithium-ion cells. For dual carbon cells to become viable new inexpensive salts and solvents that can operate at high potentials and high concentrations must be discovered. With further investigation, combinations of different anions and solvents may result in higher specific capacities that would also make dual carbon cells more viable.

Modification and intercalation of layered zirconium phosphates: a solid-state NMR monitoring.

PubMed

Bakhmutov, Vladimir I; Kan, Yuwei; Sheikh, Javeed Ahmad; González-Villegas, Julissa; Colón, Jorge L; Clearfield, Abraham

2017-07-01

Several layered zirconium phosphates treated with Zr(IV) ions, modified by monomethoxy-polyethyleneglycol-monophosphate and intercalated with doxorubicin hydrochloride have been studied by solid-state MAS NMR techniques. The organic components of the phosphates have been characterized by the 13 C{ 1 H} CP MAS NMR spectra compared with those of initial compounds. The multinuclear NMR monitoring has provided to establish structure and covalent attachment of organic/inorganic moieties to the surface and interlayer spaces of the phosphates. The MAS NMR experiments including kinetics of proton-phosphorus cross polarization have resulted in an unusual structure of zirconium phosphate 6 combining decoration of the phosphate surface by polymer units and their partial intercalation into the interlayer space. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Method of producing exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

DOEpatents

Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z.

2010-11-02

The present invention provides a method of exfoliating a layered material (e.g., graphite and graphite oxide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm. The method comprises (a) dispersing particles of graphite, graphite oxide, or a non-graphite laminar compound in a liquid medium containing therein a surfactant or dispersing agent to obtain a stable suspension or slurry; and (b) exposing the suspension or slurry to ultrasonic waves at an energy level for a sufficient length of time to produce separated nano-scaled platelets. The nano-scaled platelets are candidate reinforcement fillers for polymer nanocomposites. Nano-scaled graphene platelets are much lower-cost alternatives to carbon nano-tubes or carbon nano-fibers.

ELECTROCHEMICAL DEGRADATION OF POLYCHLOROBIPHENYLS

EPA Science Inventory

Granular graphite is an ideal conductive material for electrochemical reduction technology applications in the field. Granular graphite was used to enhance the transfer of chlorinated aliphatic compounds in saturated, low permeability soils by electroosmosis. It was also used to ...

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

Silva, Camila F.N.; Lazarin, Angélica M., E-mail: amlazarin2@uem.br; Sernaglia, Rosana L.

Graphical abstract: Scanning electron microscopy photographs of calcium phosphate (a) and intercalated with p-aminobenzoic acid (b). Highlights: ► Calcium phosphate was intercalated with p-aminobenzoic acid. ► Guest molecule contains nitrogen and oxygen atoms from amine and carboxylic groups. ► These basic centers are potentially useful for cation coordination in ethanol solution. ► Crystal morphology of compounds is lamellar, it agrees with expected structural characteristics. -- Abstract: Crystalline lamellar calcium phosphate retained 4-aminobenzoic acid inside its cavity without leaching. The intense infrared bands in the 1033 and 1010 cm{sup −1} interval confirmed the presence of the phosphonate groups attached to themore » inorganic layer, with sharp and intense peaks in X-ray diffraction patterns, which gave basal distances of 712 and 1578 pm for the original and the intercalated compounds, respectively. Solid-state {sup 31}P nuclear magnetic resonance spectra presented only one peak for the phosphate groups attached to the main inorganic polymeric structure near −2.4 ppm. The adsorption isotherms from ethanol gave the maximum adsorption capacities of 6.44 and 3.34 mmol g{sup −1} for nickel and cobalt, respectively, which stability constant and distribution coefficient followed Co > Ni.« less

Direct exfoliation of graphite to graphene in aqueous media with diazaperopyrenium dications.

PubMed

Sampath, Srinivasan; Basuray, Ashish N; Hartlieb, Karel J; Aytun, Taner; Stupp, Samuel I; Stoddart, J Fraser

2013-05-21

The 2,9-dimethyldiazaperopyrenium dication can be made from a ubiquitous and inexpensive feedstock in three simple steps as its chloride salt. When mixed with powdered graphite at 23 °C, this behemoth of a molecular compound exfoliates graphite to graphene in water under mild conditions. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aging, rejuvenation, and memory effects in short-range Ising spin glass: Cu0.5Co0.5Cl2-FeCl3 graphite bi-intercalation compound

NASA Astrophysics Data System (ADS)

Suzuki, M.; Suzuki, I. S.

2004-10-01

Non-equilibrium aging dynamics in 3D Ising spin glass Cu0.5Co0.5Cl2-FeCl3 GBIC has been studied by zero-field cooled (ZFC) magnetization and low frequency AC magnetic susceptibility ( f = 0.05 Hz), where Tg = 3.92 ± 0.11 K. The time dependence of the relaxation rate S( t) = (1/ H)dM_ZFC/dln t for the ZFC magnetization after the ZFC aging protocol, shows a peak at a characteristic time t cr near a wait time t w (aging behavior), corresponding to a crossover from quasi equilibrium dynamics to non-equilibrium. The time t cr strongly depends on t w , temperature ( T), magnetic field ( H), and the temperature shift (Δ T). The rejuvenation effect is observed in both χ^' and χ^'' under the T-shift and H-shift procedures. The memory of the specific spin configurations imprinted during the ZFC aging protocol can be recalled when the system is re-heated at a constant heating rate. The aging, rejuvenation, and memory effects observed in the present system are discussed in terms of the scaling concepts derived from numerical studies on 3D Edwards-Anderson spin glass model.

Intercalation of paracetamol into the hydrotalcite-like host

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

Kovanda, Frantisek, E-mail: Frantisek.Kovanda@vscht.cz; Maryskova, Zuzana; Kovar, Petr

2011-12-15

Hydrotalcite-like compounds are often used as host structures for intercalation of various anionic species. The product intercalated with the nonionic, water-soluble pharmaceuticals paracetamol, N-(4-hydroxyphenyl)acetamide, was prepared by rehydration of the Mg-Al mixed oxide obtained by calcination of hydrotalcite-like precursor at 500 Degree-Sign C. The successful intercalation of paracetamol molecules into the interlayer space was confirmed by powder X-ray diffraction and infrared spectroscopy measurements. Molecular simulations showed that the phenolic hydroxyl groups of paracetamol interact with hydroxide sheets of the host via the hydroxyl groups of the positively charged sites of Al-containing octahedra; the interlayer water molecules are located mostly nearmore » the hydroxide sheets. The arrangement of paracetamol molecules in the interlayer is rather disordered and interactions between neighboring molecules cause their tilting towards the hydroxide sheets. Dissolution tests in various media showed slower release of paracetamol intercalated in the hydrotalcite-like host in comparison with tablets containing the powdered pharmaceuticals. - Graphical abstract: Molecular simulations showed disordered arrangement of paracetamol molecules in the interlayer; most of the interlayer water molecules are located near the hydroxide sheets. Black-Small-Square Highlights: Black-Right-Pointing-Pointer Paracetamol was intercalated in Mg-Al hydrotalcite-like host by rehydration/reconstruction procedure. Black-Right-Pointing-Pointer Paracetamol phenolic groups interact with positively charged sites in hydroxide sheets. Black-Right-Pointing-Pointer Molecular simulations showed disordered arrangement of guest molecules in the interlayer. Black-Right-Pointing-Pointer Slower release of paracetamol intercalated in the hydrotalcite-like host was observed.« less

Potassium Secondary Batteries.

PubMed

Eftekhari, Ali; Jian, Zelang; Ji, Xiulei

2017-02-08

Potassium may exhibit advantages over lithium or sodium as a charge carrier in rechargeable batteries. Analogues of Prussian blue can provide millions of cyclic voltammetric cycles in aqueous electrolyte. Potassium intercalation chemistry has recently been demonstrated compatible with both graphite and nongraphitic carbons. In addition to potassium-ion batteries, potassium-O 2 (or -air) and potassium-sulfur batteries are emerging. Additionally, aqueous potassium-ion batteries also exhibit high reversibility and long cycling life. Because of potentially low cost, availability of basic materials, and intriguing electrochemical behaviors, this new class of secondary batteries is attracting much attention. This mini-review summarizes the current status, opportunities, and future challenges of potassium secondary batteries.

Microbial Electrosynthesis: Feeding Microbes Electricity To Convert Carbon Dioxide and Water to Multicarbon Extracellular Organic Compounds

PubMed Central

Nevin, Kelly P.; Woodard, Trevor L.; Franks, Ashley E.; Summers, Zarath M.; Lovley, Derek R.

2010-01-01

The possibility of providing the acetogenic microorganism Sporomusa ovata with electrons delivered directly to the cells with a graphite electrode for the reduction of carbon dioxide to organic compounds was investigated. Biofilms of S. ovata growing on graphite cathode surfaces consumed electrons with the reduction of carbon dioxide to acetate and small amounts of 2-oxobutyrate. Electrons appearing in these products accounted for over 85% of the electrons consumed. These results demonstrate that microbial production of multicarbon organic compounds from carbon dioxide and water with electricity as the energy source is feasible. PMID:20714445

Evaluation of new iodinated acridine derivatives for targeted radionuclide therapy of melanoma using 125I, an Auger electron emitter.

PubMed

Gardette, Maryline; Papon, Janine; Bonnet, Mathilde; Desbois, Nicolas; Labarre, Pierre; Wu, Ting-Dee; Miot-Noirault, Elisabeth; Madelmont, Jean-Claude; Guerquin-Kern, Jean-Luc; Chezal, Jean-Michel; Moins, Nicole

2011-12-01

The increasing incidence of melanoma and the lack of effective therapy on the disseminated form have led to an urgent need for new specific therapies. Several iodobenzamides or analogs are known to possess specific affinity for melanoma tissue. New heteroaromatic derivatives have been designed with a cytotoxic moiety and termed DNA intercalating agents. These compounds could be applied in targeted radionuclide therapy using (125)I, which emits Auger electrons and gives high-energy, localized irradiation. Two iodinated acridine derivatives have been reported to present an in vivo kinetic profile conducive to application in targeted radionuclide therapy. The aim of the present study was to perform a preclinical evaluation of these compounds. The DNA intercalating property was confirmed for both compounds. After radiolabeling with (125)I, the two compounds induced in vitro a significant radiotoxicity to B16F0 melanoma cells. Nevertheless, the acridine compound appeared more radiotoxic than the acridone compound. While cellular uptake was similar for both compounds, SIMS analysis and in vitro protocol showed a stronger affinity for melanin with acridone derivative, which was able to induce a predominant scavenging process in the melanosome and restrict access to the nucleus. In conclusion, the acridine derivative with a higher nuclear localization appeared a better candidate for application in targeted radionuclide therapy using (125)I.

Anthocyanin Interactions with DNA: Intercalation, Topoisomerase I Inhibition and Oxidative Reactions

PubMed Central

Webb, Michael R.; Min, Kyungmi; Ebeler, Susan E.

2009-01-01

Anthocyanins and their aglycone anthocyanidins are pigmented flavonoids found in significant amounts in many commonly consumed foods. They exhibit a complex chemistry in aqueous solution, which makes it difficult to study their chemistry under physiological conditions. Here we used a gel electrophoresis assay employing supercoiled DNA plasmid to examine the ability of these compounds (1) to intercalate DNA, (2) to inhibit human topoisomerase I through both inhibition of plasmid relaxation activity (catalytic inhibition) and stabilization of the cleavable DNA-topoisomerase complex (poisoning), and (3) to inhibit or enhance oxidative single-strand DNA nicking. We found no evidence of DNA intercalation by anthocyan(id)ins in the physiological pH range for any of the compounds used in this study—cyanidin chloride, cyanidin 3-O-glucoside, cyanidin 3,5-O-diglucoside, malvidin 3-O-glucoside and luteolinidin chloride. The anthocyanins inhibited topoisomerase relaxation activity only at high concentrations (> 50 μM) and we could find no evidence of topoisomerase I cleavable complex stabilization by these compounds. However, we observed that all of the anthocyan(id)ins used in this study were capable of inducing significant oxidative DNA strand cleavage (nicking) in the presence of 1 mM DTT (dithiothreitol), while the free radical scavenger, DMSO, at concentrations typically used in similar studies, completely inhibited DNA nicking. Finally, we propose a mechanism to explain the anthocyan(id)in induced oxidative DNA cleavage observed under our experimental conditions. PMID:19924259

First-Principles evaluation of the Chevrel phase intercalated with Be, Mg, Ca, Sr, and Ba

NASA Astrophysics Data System (ADS)

Juran, Taylor; Smeu, Manuel

Li ion batteries are extremely useful when an item requires portability and compactness, such as laptops and cell phones; due to the lightweight/compact nature of Li ion batteries. The lightweight and compact nature of Li ion batteries comes at a high cost. It is sensible to consider Li ion battery alternatives, which are more cost effective and useable when portability is not a priority. An option for a less expensive battery source is the Ca ion battery. The Ca ion battery is interesting as many researchers overlook the potential battery source due to the perplexity of finding suitable anode materials and electrolytes. In order for this technology to work, cathodes that allow for the reversible intercalation of Ca2+ ions and also provide a preferred voltage must be identified. We investigate the Chevrel phase compounds of Mo6X8 (X = S, Se, Te) which can intercalate various ions. The concentration of the ion intercalated with the Chevrel cathode is studied. We consider doped versions of the Chevrel phase, using various dopants to substitute Mo. We use density functional theory to calculate the voltage of several intercalation ions with the Chevrel material. The resulting electronic properties of the aforementioned materials will be investigated.

Multilayer Approach for Advanced Hybrid Lithium Battery.

PubMed

Ming, Jun; Li, Mengliu; Kumar, Pushpendra; Li, Lain-Jong

2016-06-28

Conventional intercalated rechargeable batteries have shown their capacity limit, and the development of an alternative battery system with higher capacity is strongly needed for sustainable electrical vehicles and hand-held devices. Herein, we introduce a feasible and scalable multilayer approach to fabricate a promising hybrid lithium battery with superior capacity and multivoltage plateaus. A sulfur-rich electrode (90 wt % S) is covered by a dual layer of graphite/Li4Ti5O12, where the active materials S and Li4Ti5O12 can both take part in redox reactions and thus deliver a high capacity of 572 mAh gcathode(-1) (vs the total mass of electrode) or 1866 mAh gs(-1) (vs the mass of sulfur) at 0.1C (with the definition of 1C = 1675 mA gs(-1)). The battery shows unique voltage platforms at 2.35 and 2.1 V, contributed from S, and 1.55 V from Li4Ti5O12. A high rate capability of 566 mAh gcathode(-1) at 0.25C and 376 mAh gcathode(-1) at 1C with durable cycle ability over 100 cycles can be achieved. Operando Raman and electron microscope analysis confirm that the graphite/Li4Ti5O12 layer slows the dissolution/migration of polysulfides, thereby giving rise to a higher sulfur utilization and a slower capacity decay. This advanced hybrid battery with a multilayer concept for marrying different voltage plateaus from various electrode materials opens a way of providing tunable capacity and multiple voltage platforms for energy device applications.

INFLUENCES OF PH AND CURRENT ON ELECTROLYTIC DECHLORINATION OF TRICHLOROETHYLENE AT A GRANULAR-GRAPHITE PACKED ELECTRODE

EPA Science Inventory

Electrolytic dechlorination using a granular-graphite packed cathode is an alternative method for the remediation of chlorinated organic compounds. Its effectiveness under various conditions needs experimental investigation. Dechlorination of trichloroethylene (TCE) was conducted...

Toxicity, mutagenicity and transport in Saccharomyces cerevisiae of three popular DNA intercalating fluorescent dyes.

PubMed

Sayas, Enric; García-López, Federico; Serrano, Ramón

2015-09-01

We have compared the toxicity, mutagenicity and transport in Saccharomyces cerevisiae of three DNA-intercalating fluorescent dyes widely used to stain DNA in gels. Safety data about ethidium bromide (EtBr) are contradictory, and two compounds of undisclosed structure (Redsafe and Gelred) have been proposed as safe alternatives. Our results indicate that all three compounds inhibit yeast growth, with Gelred being the most inhibitory and also the only one causing cell death. EtBr and Gelred, but not Redsafe, induce massive formation of petite (non-respiratory) mutants, but only EtBr induces massive loss of mitochondrial DNA. All three compounds increase reversion of a chromosomal point mutation (lys2-801(amber) ), with Gelred being the most mutagenic and Redsafe the least. These dyes are all cationic and are probably taken by cells through non-selective cation channels. We could measure the glucose-energized transport of EtBr and Gelred inside the cells, while uptake of Redsafe was below our detection limit. We conclude that although all three compounds are toxic and mutagenic in the yeast system, Redsafe is the safest for yeast, probably because of very limited uptake by these cells. Copyright © 2015 John Wiley & Sons, Ltd.

Electronic and total energy properties of ternary and quaternary semiconductor compounds, alloys, and superlattices: Theoretical study of Cu/graphite bonding

NASA Technical Reports Server (NTRS)

Lambrecht, Walter R. L.

1992-01-01

The goals of the research were to provide a fundamental science basis for why the bonding of Cu to graphite is weak, to critically evaluate the previous analysis of the wetting studies with particular regard to the values used for the surface energies of Cu and graphite, and to make recommendations for future experiments or other studies which could advance the understanding and solution of this technological problem. First principles electronic structure calculations were used to study the problem. These are based on density functional theory in the local density approximation and the use of the linear muffin-tin orbital band structure method. Calculations were performed for graphite monolayers, single crystal graphite with the hexagonal AB stacking, bulk Cu, Cu(111) surface, and Cu/graphite superlattices. The study is limited to the basal plane of graphite because this is the graphite plane exposed to Cu and graphite surface energies and combined with the measured contact angles to evaluate the experimental adhesion energy.

IDENTIFICATION OF CHLOROMETHANE FROMATION PATHS DURING ELECTROCHEMICAL DECHLORINATION OF TCE USING GRAPHITE ELECTRODES

EPA Science Inventory

The purpose of this research is to investigate the formation of chloromethane during TCE dechlorination in a mixed electrochemical reactor using graphite electrodes. Chloromethane was the major chlorinated organic compound detected in previous dechlorination experiments. In order...

IDENTIFICATION OF CHLOROMETHANE FORMATION PATHS DURING ELECTROCHEMICAL DECHLORINATION OF TCE USING GRAPHITE ELECTRODES

EPA Science Inventory

The purpose of this research is to investigate the formation of chloromethane during TCE dechlorination in a mixed electrochemical reactor using graphite electrodes. Chloromethane was the major chlorinated organic compound detected in previous dechlorination experiments. In order...

Radiation damage and thermal shock response of carbon-fiber-reinforced materials to intense high-energy proton beams

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

Simos, N.; Zhong, Z.; Ghose, S.

Here, a comprehensive study on the effects of energetic protons on carbon-fiber composites and compounds under consideration for use as low-Z pion production targets in future high-power accelerators and low-impedance collimating elements for intercepting TeV-level protons at the Large Hadron Collider has been undertaken addressing two key areas, namely, thermal shock absorption and resistance to irradiation damage. Carbon-fiber composites of various fiber weaves have been widely used in aerospace industries due to their unique combination of high temperature stability, low density, and high strength. The performance of carbon-carbon composites and compounds under intense proton beams and long-term irradiation have beenmore » studied in a series of experiments and compared with the performance of graphite. The 24-GeV proton beam experiments confirmed the inherent ability of a 3D C/C fiber composite to withstand a thermal shock. A series of irradiation damage campaigns explored the response of different C/C structures as a function of the proton fluence and irradiating environment. Radiolytic oxidation resulting from the interaction of oxygen molecules, the result of beam-induced radiolysis encountered during some of the irradiation campaigns, with carbon atoms during irradiation with the presence of a water coolant emerged as a dominant contributor to the observed structural integrity loss at proton fluences ≥5×10 20 p/cm 2. The carbon-fiber composites were shown to exhibit significant anisotropy in their dimensional stability driven by the fiber weave and the microstructural behavior of the fiber and carbon matrix accompanied by the presence of manufacturing porosity and defects. Carbon-fiber-reinforced molybdenum-graphite compounds (MoGRCF) selected for their impedance properties in the Large Hadron Collider beam collimation exhibited significant decrease in postirradiation load-displacement behavior even after low dose levels (~5×10 18 p cm -2). In addition, the studied MoGRCF compound grade suffered a high degree of structural degradation while being irradiated in a vacuum after a fluence ~5×10 20 p cm -2. Finally, x-ray diffraction studies on irradiated C/C composites and a carbon-fiber-reinforced Mo-graphite compound revealed (a) low graphitization in the “as-received” 3D C/C and high graphitization in the MoGRCF compound, (b) irradiation-induced graphitization of the least crystallized phases in the carbon fibers of the 2D and 3D C/C composites, (c) increased interplanar distances along the c axis of the graphite crystal with increasing fluence, and (d) coalescence of interstitial clusters after irradiation forming new crystalline planes between basal planes and excellent agreement with fast neutron irradiation effects.« less

Radiation damage and thermal shock response of carbon-fiber-reinforced materials to intense high-energy proton beams

DOE PAGES

Simos, N.; Zhong, Z.; Ghose, S.; ...

2016-11-16

Here, a comprehensive study on the effects of energetic protons on carbon-fiber composites and compounds under consideration for use as low-Z pion production targets in future high-power accelerators and low-impedance collimating elements for intercepting TeV-level protons at the Large Hadron Collider has been undertaken addressing two key areas, namely, thermal shock absorption and resistance to irradiation damage. Carbon-fiber composites of various fiber weaves have been widely used in aerospace industries due to their unique combination of high temperature stability, low density, and high strength. The performance of carbon-carbon composites and compounds under intense proton beams and long-term irradiation have beenmore » studied in a series of experiments and compared with the performance of graphite. The 24-GeV proton beam experiments confirmed the inherent ability of a 3D C/C fiber composite to withstand a thermal shock. A series of irradiation damage campaigns explored the response of different C/C structures as a function of the proton fluence and irradiating environment. Radiolytic oxidation resulting from the interaction of oxygen molecules, the result of beam-induced radiolysis encountered during some of the irradiation campaigns, with carbon atoms during irradiation with the presence of a water coolant emerged as a dominant contributor to the observed structural integrity loss at proton fluences ≥5×10 20 p/cm 2. The carbon-fiber composites were shown to exhibit significant anisotropy in their dimensional stability driven by the fiber weave and the microstructural behavior of the fiber and carbon matrix accompanied by the presence of manufacturing porosity and defects. Carbon-fiber-reinforced molybdenum-graphite compounds (MoGRCF) selected for their impedance properties in the Large Hadron Collider beam collimation exhibited significant decrease in postirradiation load-displacement behavior even after low dose levels (~5×10 18 p cm -2). In addition, the studied MoGRCF compound grade suffered a high degree of structural degradation while being irradiated in a vacuum after a fluence ~5×10 20 p cm -2. Finally, x-ray diffraction studies on irradiated C/C composites and a carbon-fiber-reinforced Mo-graphite compound revealed (a) low graphitization in the “as-received” 3D C/C and high graphitization in the MoGRCF compound, (b) irradiation-induced graphitization of the least crystallized phases in the carbon fibers of the 2D and 3D C/C composites, (c) increased interplanar distances along the c axis of the graphite crystal with increasing fluence, and (d) coalescence of interstitial clusters after irradiation forming new crystalline planes between basal planes and excellent agreement with fast neutron irradiation effects.« less

Radiation damage and thermal shock response of carbon-fiber-reinforced materials to intense high-energy proton beams

NASA Astrophysics Data System (ADS)

Simos, N.; Zhong, Z.; Ghose, S.; Kirk, H. G.; Trung, L.-P.; McDonald, K. T.; Kotsina, Z.; Nocera, P.; Assmann, R.; Redaelli, S.; Bertarelli, A.; Quaranta, E.; Rossi, A.; Zwaska, R.; Ammigan, K.; Hurh, P.; Mokhov, N.

2016-11-01

A comprehensive study on the effects of energetic protons on carbon-fiber composites and compounds under consideration for use as low-Z pion production targets in future high-power accelerators and low-impedance collimating elements for intercepting TeV-level protons at the Large Hadron Collider has been undertaken addressing two key areas, namely, thermal shock absorption and resistance to irradiation damage. Carbon-fiber composites of various fiber weaves have been widely used in aerospace industries due to their unique combination of high temperature stability, low density, and high strength. The performance of carbon-carbon composites and compounds under intense proton beams and long-term irradiation have been studied in a series of experiments and compared with the performance of graphite. The 24-GeV proton beam experiments confirmed the inherent ability of a 3D C/C fiber composite to withstand a thermal shock. A series of irradiation damage campaigns explored the response of different C/C structures as a function of the proton fluence and irradiating environment. Radiolytic oxidation resulting from the interaction of oxygen molecules, the result of beam-induced radiolysis encountered during some of the irradiation campaigns, with carbon atoms during irradiation with the presence of a water coolant emerged as a dominant contributor to the observed structural integrity loss at proton fluences ≥5 ×1020 p /cm2 . The carbon-fiber composites were shown to exhibit significant anisotropy in their dimensional stability driven by the fiber weave and the microstructural behavior of the fiber and carbon matrix accompanied by the presence of manufacturing porosity and defects. Carbon-fiber-reinforced molybdenum-graphite compounds (MoGRCF) selected for their impedance properties in the Large Hadron Collider beam collimation exhibited significant decrease in postirradiation load-displacement behavior even after low dose levels (˜5 ×1018 p cm-2 ). In addition, the studied MoGRCF compound grade suffered a high degree of structural degradation while being irradiated in a vacuum after a fluence ˜5 ×1020 p cm-2 . Finally, x-ray diffraction studies on irradiated C/C composites and a carbon-fiber-reinforced Mo-graphite compound revealed (a) low graphitization in the "as-received" 3D C/C and high graphitization in the MoGRCF compound, (b) irradiation-induced graphitization of the least crystallized phases in the carbon fibers of the 2D and 3D C/C composites, (c) increased interplanar distances along the c axis of the graphite crystal with increasing fluence, and (d) coalescence of interstitial clusters after irradiation forming new crystalline planes between basal planes and excellent agreement with fast neutron irradiation effects.

γ-Irradiation assisted synthesis of graphene oxide sheets supported Ag nanoparticles with single crystalline structure and parabolic distribution from interlamellar limitation

NASA Astrophysics Data System (ADS)

Yue, Yunhao; Zhou, Baoming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei; Liu, Liangsen; Kuang, Liyun; Ma, Meijun; Fu, Hongjun

2017-05-01

This paper reported a method to fabricate graphene oxide sheets supported Ag nanoparticles (AgNPs/GOS) with single crystalline structure and parabolic distribution without surfactant or functional agent. We used imidazole silver nitrate as intercalation precursor into the layers of graphite oxide, and subsequently reduction and growth of interlamellar AgNPs were induced via γ-irradiation. The results illustrated that the synergism of interlamellar limitation of graphite oxide and fragmentation ability of γ-irradiation could prevent coalescent reaction of AgNPs with other oligomeric clusters, and the single crystalline and small-sized (below 13.9 nm) AgNPs were prepared. Moreover, the content and size of AgNPs exhibited parabolic distribution on GOS surface because the graphite oxide exfoliated to GOS from the edge to the central area of layers. In addition, complete exfoliation degree of GOS and large-sized AgNPs were obtained simultaneously under suitable silver ions concentration. Optimized composites exhibited outstanding surface-enhanced Raman scattering properties for crystal violet with enhancement factor of 1.3 × 106 and detection limit of 1.0 × 10-7 M, indicating that the AgNPs/GOS composites could be applied to trace detection of organic dyes molecules. Therefore, this study presented a strategy for developing GOS supported nanometal with single crystalline structure and parabolic distribution based on γ-irradiation.

Enhanced adsorption of Eu(III) on mesoporous Al2O3/expanded graphite composites investigated by macroscopic and microscopic techniques.

PubMed

Sun, Yubing; Chen, Changlun; Tan, Xiaoli; Shao, Dadong; Li, Jiaxing; Zhao, Guixia; Yang, Shubin; Wang, Qi; Wang, Xiangke

2012-11-21

Mesoporous Al(2)O(3) was intercalated into an expanded graphite (EG) interlayer to prepare mesoporous Al(2)O(3)/EG composites. The basal spacing of mesoporous Al(2)O(3)/EG composites was enlarged as compared to raw graphite from the X-ray diffraction analysis. The massive surface functional groups and wedge-shaped pores were observed in terms of potentiometric acid-base titration analysis and scanning electron microscope, respectively. The pH-dependent adsorption of Eu(III) on mesoporous Al(2)O(3)/EG composites was evidently independent of ionic strength. The maximum adsorption capacity of Eu(III) on mesoporous Al(2)O(3)/EG composites at pH 6.0 and T = 293 K was calculated to be 5.14 mg g(-1). Desorption kinetics and cyclic operation results showed that mesoporous Al(2)O(3)/EG composites presented high hydrothermal stability in aqueous solution. The thermodynamic parameters suggested that Eu(III) adsorption on mesoporous Al(2)O(3)/EG composites is an endothermic and a spontaneous process. The decrease of Eu-O bond distance with the increasing pH demonstrated that the adsorption mechanism between Eu(III) and mesoporous Al(2)O(3)/EG composites would shift from outer-sphere surface complexation to inner-sphere surface complexation in terms of extended X-ray absorption fine structure spectroscopy analysis.

Bending fracture in carbon nanotubes.

PubMed

Kuo, Wen-Shyong; Lu, Hsin-Fang

2008-12-10

A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed.

Preparation and properties of single-walled nanotubes filled with inorganic compounds

NASA Astrophysics Data System (ADS)

Eliseev, Andrei A.; Kharlamova, M. V.; Chernysheva, M. V.; Lukashin, Alexey V.; Tretyakov, Yuri D.; Kumskov, A. S.; Kiselev, N. A.

2009-09-01

The state-of-the-art methods for filling single-walled carbon nanotubes (SWNTs) are analyzed systematically. In situ and ex situ approaches for filling SWNTs are addressed. They are based on both intercalation of inorganic substances from the gas phase, solution or melts inside SWNTs and the formation of nanocrystals inside the channels as a result of chemical reactions. A comparative evaluation of these methods is performed, and major requirements for successful formation of '1D-crystal@SWNT' nanocomposites are formulated. The functional properties of the intercalated single-walled nanotubes and their possible applications in modern nanotechnologies are discussed.

Unexpected DNA affinity and sequence selectivity through core rigidity in guanidinium-based minor groove binders.

PubMed

Nagle, Padraic S; McKeever, Caitriona; Rodriguez, Fernando; Nguyen, Binh; Wilson, W David; Rozas, Isabel

2014-09-25

In this paper we report the design and biophysical evaluation of novel rigid-core symmetric and asymmetric dicationic DNA binders containing 9H-fluorene and 9,10-dihydroanthracene cores as well as the synthesis of one of these fluorene derivatives. First, the affinity toward particular DNA sequences of these compounds and flexible core derivatives was evaluated by means of surface plasmon resonance and thermal denaturation experiments finding that the position of the cations significantly influence the binding strength. Then their affinity and mode of binding were further studied by performing circular dichroism and UV studies and the results obtained were rationalized by means of DFT calculations. We found that the fluorene derivatives prepared have the ability to bind to the minor groove of certain DNA sequences and intercalate to others, whereas the dihydroanthracene compounds bind via intercalation to all the DNA sequences studied here.

Interface confined hydrogen evolution reaction in zero valent metal nanoparticles-intercalated molybdenum disulfide

PubMed Central

Chen, Zhongxin; Leng, Kai; Zhao, Xiaoxu; Malkhandi, Souradip; Tang, Wei; Tian, Bingbing; Dong, Lei; Zheng, Lirong; Lin, Ming; Yeo, Boon Siang; Loh, Kian Ping

2017-01-01

Interface confined reactions, which can modulate the bonding of reactants with catalytic centres and influence the rate of the mass transport from bulk solution, have emerged as a viable strategy for achieving highly stable and selective catalysis. Here we demonstrate that 1T′-enriched lithiated molybdenum disulfide is a highly powerful reducing agent, which can be exploited for the in-situ reduction of metal ions within the inner planes of lithiated molybdenum disulfide to form a zero valent metal-intercalated molybdenum disulfide. The confinement of platinum nanoparticles within the molybdenum disulfide layered structure leads to enhanced hydrogen evolution reaction activity and stability compared to catalysts dispersed on carbon support. In particular, the inner platinum surface is accessible to charged species like proton and metal ions, while blocking poisoning by larger sized pollutants or neutral molecules. This points a way forward for using bulk intercalated compounds for energy related applications. PMID:28230105

Controlling the photoconductivity: Graphene oxide and polyaniline self assembled intercalation

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

Vempati, Sesha, E-mail: svempati01@qub.ac.uk; Ozcan, Sefika; Department of Polymer Science and Technology, Middle East Technical University, Ankara 06800

2015-02-02

We report on controlling the optoelectronic properties of self-assembled intercalating compound of graphene oxide (GO) and HCl doped polyaniline (PANI). Optical emission and X-ray diffraction studies revealed a secondary doping phenomenon of PANI with –OH and –COOH groups of GO, which essentially arbitrate the intercalation. A control on the polarity and the magnitude of the photoresponse (PR) is harnessed by manipulating the weight ratios of PANI to GO (viz., 1:1.5 and 1:2.2 are abbreviated as PG1.5 and PG2.2, respectively), where ±PR = 100(R{sub Dark} – R{sub UV-Vis})/R{sub Dark} and R corresponds to the resistance of the device in dark or UV-Vis illumination.more » To be precise, the PR from GO, PANI, PG1.5, and PG2.2 are +34%, −111%, −51%, and +58%, respectively.« less

Chemical Characterization and Removal of C-14 from Irradiated Graphite-12010

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

Cleaver, James; McCrory, Shilo; Smith, Tara E.

2012-07-01

Quantities of irradiated graphite waste are expected to drastically increase, which indicates the need for a graphite waste management strategy. Of greatest concern for long-term disposal of irradiated graphite is carbon-14 (C-14), with a half-life of 5730 years. Study of irradiated graphite from nuclear reactors indicates C-14 is concentrated on the outer 5 mm of the graphite structure. The aim of the research described here is to identify the chemical form of C-14 in irradiated graphite and develop a practical method by which C-14 can be removed. Characterization of pre- and post-irradiation graphite was conducted to determine bond type, functionalmore » groups, location and concentration of C-14 and its precursors via the use of surface sensitive characterization techniques. Because most surface C-14 originates from neutron activation of nitrogen, an understanding of nitrogen bonding to graphite may lead to a greater understanding of the formation pathway of C-14. However, no single technique provides a complete picture. Therefore, a portfolio of techniques has been developed, with each technique providing another piece to the puzzle that is the chemical nature of the C-14. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Raman Spectroscopy were used to evaluate the morphological features of graphite samples. The concentration, chemical composition, and bonding characteristics of C-14 and its precursors were determined through X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (SIMS), and Auger and Energy Dispersive X-ray Analysis Spectroscopy (EDX). High-surface-area graphite foam, POCOFoam{sup R}, was exposed to liquid nitrogen and irradiated. Characterization of this material has shown C-14 to C-12 ratios of 0.035. This information was used to optimize the thermal treatment of graphite. Thermal treatment of irradiated graphite as reported by Fachinger et al. (2007) uses naturally adsorbed oxygen complexes to gasify graphite, thus its effectiveness is highly dependent on the availability of adsorbed oxygen compounds. In research presented, the quantity and form of adsorbed oxygen complexes in pre- and post irradiated graphite was studied using SIMS and XPS. SIMS and XPS detected adsorbed oxygen compounds on both irradiated and unirradiated graphite. During thermal treatment graphite samples are heated in the presence of inert argon gas, which carries off gaseous products released during treatment. Experiments were performed at 900 deg. C and 1400 deg. C to evaluate the selective removal of C-14. (authors)« less

Reversible intercalation of ammonia molecules into a layered double hydroxide structure without exchanging nitrate counter-ions

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

Carbajal Arizaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.m; Wypych, Fernando; Castillon Barraza, Felipe

2010-10-15

A zinc/aluminum LDH was precipitated with recycled ammonia from a chemical vapor deposition reaction. The LDH presented a crystalline phase with basal distance of 8.9 A, typical for nitrate-containing LDHs, and another phase with a basal distance of 13.9 A. Thermal treatment at 150 {sup o}C eliminated the phase with the bigger basal distance leaving only the anhydrous nitrate-intercalated LDH structure with 8.9 A. Intense N-H stretching modes in the FTIR spectra suggested that the expansion was due to intercalation of ammonia in the form of [NH{sub 4}(NH{sub 3}){sub n}]{sup +} species. When additional samples were precipitated with pure ammonia,more » the conventional LDH nitrate structure was obtained (8.9 A basal distance) at pH=7, as well as a pure crystalline phase with 13.9 A basal distance at pH=10 due to ammonia intercalation that can be removed by heating at 150 {sup o}C or by stirring in acetone, confirming a unusual sensu stricto intercalation process into a LDH without exchanging nitrate ions. - Graphical abstract: LDH-nitrate precipitated with ammonia expands the interlayer space if ammonia is bubbled up to pH 10. The basal distance decreased when the compound was heated at 150 {sup o}C or stirred in acetone. Nitrate ions are not exchanged.« less

Synthesis and characterization of Mg-Al-layered double hydroxides intercalated with cubane-1,4-dicarboxylate anions.

PubMed

Rezvani, Zolfaghar; Arjomandi Rad, Farzad; Khodam, Fatemeh

2015-01-21

In the present work, Mg2Al-layered double hydroxide (LDH) intercalated with cubane-1,4-dicarboxylate anions was prepared from the reaction of solutions of Mg(ii) and Al(iii) nitrate salts with an alkaline solution of cubane-1,4-dicarboxylic acid by using the coprecipitation method. The successful preparation of a nanohybrid of cubane-1,4-dicarboxylate(cubane-dc) anions with LDH was confirmed by powder X-ray diffraction, FTIR spectroscopy and thermal gravimetric analysis (TGA). The increase in the basal spacing of LDHs from 8.67 Å to 13.40 Å shows that cubane-dc anions were successfully incorporated into the interlayer space. Thermogravimetric analyses confirm that the thermal stability of the intercalated cubane-dc anions is greater than that of the pure form before intercalation because of host-guest interactions involving hydrogen bonds. The interlayer structure, hydrogen bonding, and subsequent distension of LDH compounds containing cubane-dc anions were shown by molecular simulation. The RDF (radial distribution function), mean square displacement (MSD), and self-diffusion coefficient were calculated using the trajectory files on the basis of molecular dynamics (MD) simulations, and the results indicated that the cubane-dc anions were more stable when intercalated into the LDH layers. A good agreement was obtained between calculated and measured X-ray diffraction patterns and between experimental and calculated basal spacings.

Synthesis and investigation of proton conductivity for intercalated kaolinite with 4-amidinopyridinium chloride

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

Ren, Li-Te; College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009; Li, Xiao-Pei

2015-12-15

The proton-conducting materials have potential application in devices such as fuel cells. In this study, a mineral kaolinite-based proton conducting material, kaolinite-4-amidinopyridinium hydrochloride (K-4-APy–HCl), was synthesized by the intercalated compound kaolinite-4-amidinopyridine (K-4-APy) adsorbing volatilizing HCl. The thermogravimetric analysis (TG), powder X-ray diffraction (PXRD) and IR spectrum confirmed the HCl successfully inserting into the interlayer space of kaolinite and the 4-aminopyridine being protonated. The intercalation efficiency is estimated to be ca. 85.6%. With respect to K-4-APy, the interlayer space expends by 1.53 Å. The thermal decomposition mechanism was studied by PXRD and TG techniques. The K-4-APy–HCl shows proton conductivity with σ=3.379×10{supmore » −8} S cm{sup −1} at 373 K and E{sub a}=1.159 eV in the anhydrous condition, which are comparable to MOFs-based proton conducting materials. - Graphical abstract: The intercalated hybrid of mineral kaolinite with 4-amidinopyridinium hydrochloride is prepared to use as proton conducting material. - Highlights: • A new strategy is proposed for preparation of kaolinite-based proton conductor. • Intercalatied hybrid was prepared by sequentially inserting 4-amidinopyridine and adsorbing HCl. • The proton conductivity of intercalated hybrid is comparable to MOFs-based proton-conductors.« less

Fabrication of composite films containing zirconia and cationic polyelectrolytes.

PubMed

Pang, Xin; Zhitomirsky, Igor

2004-03-30

Composite films were prepared by electrophoretic deposition of poly(ethylenimine) or poly(allylamine hydrochloride) combined with cathodic precipitation of zirconia. Films of up to several micrometers thick were obtained on Ni, Pt, stainless-steel, graphite, and carbon-felt substrates. When the concentration of polyelectrolytes in solutions and the deposition time were varied, the amount of the deposited material and its composition can be varied. The electrochemical intercalation of yttria-stabilized zirconia particles into the composite films has been demonstrated. Obtained results pave the way for the electrodeposition of other polymer-ceramic composites. The deposits were studied by thermogravimetric analysis, X-ray diffraction analysis, scanning electron microscopy, and atomic force microscopy. The mechanisms of deposition are discussed.

1,8-Naphthalimide: A Potent DNA Intercalator and Target for Cancer Therapy.

PubMed

Tandon, Runjhun; Luxami, Vijay; Kaur, Harsovin; Tandon, Nitin; Paul, Kamaldeep

2017-10-01

The poor pharmacokinetics, side effects and particularly the rapid emergence of drug resistance compromise the efficiency of clinically used anticancer drugs. Therefore, the discovery of novel and effective drugs is still an extremely primary mission. Naphthalimide family is one of the highly active anticancer drug based upon effective intercalator with DNA. In this article, we review the discovery and development of 1,8-naphthalimide moiety, and, especially, pay much attention to the structural modifications and structure activity relationships. The review demonstrates how modulation of the moiety affecting naphthalimide compound for DNA binding that is achieved to afford a profile of antitumor activity. The DNA binding of imide and ring substitution at naphthalimide, bisnaphthalimide, naphthalimide-metal complexes is achieved by molecular recognition through intercalation mode. Thus, this synthetic/natural small molecule can act as a drug when activation or inhibition of DNA function, is required to cure or control the cancer disease. The present study is a review of the advances in 1,8-naphthalimide-related research, with a focus on how such derivatives are intercalated into DNA for their anticancer activities. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrolytic exfoliation of graphite in water with multifunctional electrolytes: en route towards high quality, oxide-free graphene flakes.

PubMed

Munuera, J M; Paredes, J I; Villar-Rodil, S; Ayán-Varela, M; Martínez-Alonso, A; Tascón, J M D

2016-02-07

Electrolytic--usually referred to as electrochemical--exfoliation of graphite in water under anodic potential holds enormous promise as a simple, green and high-yield method for the mass production of graphene, but currently suffers from several drawbacks that hinder its widespread adoption, one of the most critical being the oxidation and subsequent structural degradation of the carbon lattice that is usually associated with such a production process. To overcome this and other limitations, we introduce and implement the concept of multifunctional electrolytes. The latter are amphiphilic anions (mostly polyaromatic hydrocarbons appended with sulfonate groups) that play different relevant roles as (1) an intercalating electrolyte to trigger exfoliation of graphite into graphene flakes, (2) a dispersant to afford stable aqueous colloidal suspensions of the flakes suitable for further use, (3) a sacrificial agent to prevent graphene oxidation during exfoliation and (4) a linker to promote nanoparticle anchoring on the graphene flakes, yielding functional hybrids. The implementation of this strategy with some selected amphiphiles even furnishes anodically exfoliated graphenes of a quality similar to that of flakes produced by direct, ultrasound- or shear-induced exfoliation of graphite in the liquid phase (i.e., almost oxide- and defect-free). These high quality materials were used for the preparation of catalytically efficient graphene-Pt nanoparticle hybrids, as demonstrated by model reactions (reduction of nitroarenes). The multifunctional performance of these electrolytes is also discussed and rationalized, and a mechanistic picture of their oxidation-preventing ability is proposed. Overall, the present results open the prospect of anodic exfoliation as a competitive method for the production of very high quality graphene flakes.

Viscoelastic properties of graphene-based epoxy resins

NASA Astrophysics Data System (ADS)

Nobile, Maria Rossella; Fierro, Annalisa; Rosolia, Salvatore; Raimondo, Marialuigia; Lafdi, Khalid; Guadagno, Liberata

2015-12-01

In this paper the viscoelastic properties of an epoxy resin filled with graphene-based nanoparticles have been investigated in the liquid state, before curing, by means of a rotational rheometer equipped with a parallel plate geometry. Exfoliated graphite was prepared using traditional acid intercalation followed by a sudden treatment at high temperature (900°C). The percentage of exfoliated graphite was found to be 56%. The epoxy matrix was prepared by mixing a tetrafunctional precursor with a reactive diluent which produces a significant decrease in the viscosity of the epoxy precursor so that the dispersion step of nanofillers in the matrix can easily occur. The hardener agent, the 4,4-diaminodiphenyl sulfone (DDS), was added at a stoichiometric concentration with respect to all the epoxy rings. The inclusion of the partially exfoliated graphite (pEG) in the formulated epoxy mixture significantly modifies the rheological behaviour of the mixture itself. The epoxy mixture, indeed, shows a Newtonian behaviour while, at 3 wt % pEG content, the complex viscosity of the nanocomposite clearly shows a shear thinning behaviour with η* values much higher at the lower frequencies. The increase in complex viscosity with the increasing of the partially exfoliated graphite content was mostly caused by a dramatic increase in the storage modulus. All the graphene-based epoxy mixtures were cured by a two-stage curing cycles: a first isothermal stage was carried out at the lower temperature of 125°C for 1 hour while the second isothermal stage was performed at the higher temperature of 200°C for 3 hours. The mechanical properties of the cured nanocomposites show high values in the storage modulus and glass transition temperature.

Removal of tyrosol from water by adsorption on carbonaceous materials and electrochemical advanced oxidation processes.

PubMed

Flores, Nelly; Sharif, Farbod; Yasri, Nael; Brillas, Enric; Sirés, Ignasi; Roberts, Edward P L

2018-06-01

This work compares the ability of physical and chemical treatments, namely adsorption and electrochemical advanced oxidation processes, to remove tyrosol from aqueous medium. Adsorption on graphene nanoplatelets (GNPs) performed much better than that with a graphite intercalation compound. Adsorption isotherms were found to follow the Freundlich model (R 2  = 0.96), which is characteristic of a chemisorption process. Successful electrochemical regeneration enables 5 successive adsorption/regeneration cycles before corrosion of GNPs occurs. Other typical aromatic contaminants that may coexist with tyrosol can be also adsorbed on GNPs. Percentage of regeneration efficiency of GNPs showed a higher affinity towards Lewis acids group compounds and a lower one towards Lewis base. The treatment of 100 mL of 0.723 mM tyrosol solutions in non-chlorinated and chlorinated matrices at pH 3.0 was carried out by electrochemical oxidation with electrogenerated H 2 O 2 (EO-H 2 O 2 ), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF). Trials were made with a BDD anode and an air-diffusion cathode at 10-30 mA cm -2 . Hydroxyl radicals formed at the anode from water oxidation and/or in the bulk from Fenton's reaction between added Fe 2+ and generated H 2 O 2 , along with active chlorine produced in chlorinated medium, were the main oxidants. Tyrosol concentration always decayed following a pseudo-first-order kinetics and its mineralization rose as EO-H 2 O 2  < EF < PEF, more rapidly in the chlorinated matrix. The potent photolysis of intermediates under UVA radiation explained the almost total mineralization achieved by PEF in the latter medium. The effect of current density and tyrosol content on the performance of all processes was examined. Copyright © 2018 Elsevier Ltd. All rights reserved.

Acridine-intercalator based hypoxia selective cytotoxins

DOEpatents

Papadopoulou-Rosenzweig, Maria; Bloomer, William D.; Bloomer, William D.

1994-01-01

Hypoxia selective cytotoxins of the general formula ##STR1## wherein n is from 1 to 5, and NO.sub.2 is in at least one of the 2, 4 or 5-positions of the imidazole. Such compounds have utility as radiosensitizers and chemosensitizers.

Ultraviolet-induced sister chromatid exchanges in V-79 cells with normal and BrdUrd-substituted DNA and the influence of intercalating substances and cysteine

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

Speit, G.; Mehnert, K.; Wolf, M.

1982-06-01

The influence of intercalating substances (proflavine, ethidium bromide) and of an SH compound (L-cysteine) on uv-induced sister chromatid exchanges (SCEs) was investigated in V-79 cells with normal and BrdUrd-substituted DNA. The results are discussed in relation to the primary damages leading to SCE induction produced by uv irradiation. The data indicate that neither the pyrimidine dimers nor DNA single-strand breaks are the primary cause of SCE induction, and that the damages leading to SCEs by uv irradiation differ from those which cause chromosome aberrations.

Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

DOEpatents

Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher; Lane, George Hamilton; Morgan, Dane; Nevin, Josh; Ceder, Gerbrand; Persson, Kristin Aslaug; Eaglesham, David

2015-10-27

Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqeuous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

Superconducting selenides intercalated with organic molecules: synthesis, crystal structure, electric and magnetic properties, superconducting properties, and phase separation in iron based-chalcogenides and hybrid organic-inorganic superconductors

NASA Astrophysics Data System (ADS)

Krzton-Maziopa, Anna; Pesko, Edyta; Puzniak, Roman

2018-06-01

Layered iron-based superconducting chalcogenides intercalated with molecular species are the subject of intensive studies, especially in the field of solid state chemistry and condensed matter physics, because of their intriguing chemistry and tunable electric and magnetic properties. Considerable progress in the research, revealing superconducting inorganic–organic hybrid materials with transition temperatures to superconducting state, T c, up to 46 K, has been brought in recent years. These novel materials are synthesized by low-temperature intercalation of molecular species, such as solvates of alkali metals and nitrogen-containing donor compounds, into layered FeSe-type structure. Both the chemical nature as well as orientation of organic molecules between the layers of inorganic host, play an important role in structural modifications and may be used for fine tuning of superconducting properties. Furthermore, a variety of donor species compatible with alkali metals, as well as the possibility of doping also in the host structure (either on Fe or Se sites), makes this system quite flexible and gives a vast array of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed with a particular attention paid to the influence of the unique nature of intercalating species on the crystal structure and physical properties of the hybrid inorganic–organic materials. To get a full picture of these materials, a comprehensive description of the most effective chemical and electrochemical methods, utilized for synthesis of intercalated species, with critical evaluation of their strong and weak points, related to feasibility of synthesis, phase purity, crystal size and morphology of final products, is included as well.

Polymer/graphite oxide composites as high-performance materials for electric double layer capacitors

NASA Astrophysics Data System (ADS)

Tien, Chien-Pin; Teng, Hsisheng

A single graphene sheet represents a carbon material with the highest surface area available to accommodating molecules or ions for physical and chemical interactions. Here we demonstrate in an electric double layer capacitor the outstanding performance of graphite oxide for providing a platform for double layer formation. Graphite oxide is generally the intermediate compound for obtaining separated graphene sheets. Instead of reduction with hydrazine, we incorporate graphite oxide with a poly(ethylene oxide)-based polymer and anchor the graphene oxide sheets with poly(propylene oxide) diamines. This polymer/graphite oxide composite shows in a "dry" gel-electrolyte system a double layer capacitance as high as 130 F g -1. The polymer incorporation developed here can significantly diversify the application of graphene-based materials in energy storage devices.

A ruthenium polypyridyl intercalator stalls DNA replication forks, radiosensitizes human cancer cells and is enhanced by Chk1 inhibition

NASA Astrophysics Data System (ADS)

Gill, Martin R.; Harun, Siti Norain; Halder, Swagata; Boghozian, Ramon A.; Ramadan, Kristijan; Ahmad, Haslina; Vallis, Katherine A.

2016-08-01

Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)]2+ (dppz = dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls replication fork progression in HeLa human cervical cancer cells. In response to this replication blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment. Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)]2+ before external beam ionising radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more efficient cancer cell killing.

A ruthenium polypyridyl intercalator stalls DNA replication forks, radiosensitizes human cancer cells and is enhanced by Chk1 inhibition.

PubMed

Gill, Martin R; Harun, Siti Norain; Halder, Swagata; Boghozian, Ramon A; Ramadan, Kristijan; Ahmad, Haslina; Vallis, Katherine A

2016-08-25

Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)](2+) (dppz = dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls replication fork progression in HeLa human cervical cancer cells. In response to this replication blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment. Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)](2+) before external beam ionising radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more efficient cancer cell killing.

Structures and electrochemical performances of pyrolized carbons from graphite oxides for electric double-layer capacitor

NASA Astrophysics Data System (ADS)

Kim, Ick-Jun; Yang, Sunhye; Jeon, Min-Je; Moon, Seong-In; Kim, Hyun-Soo; Lee, Yoon-Pyo; An, Kye-Hyeok; Lee, Young-Hee

The structural features and the electrochemical performances of pyrolized needle cokes from oxidized cokes are examined and compared with those of KOH-activated needle coke. The structure of needle coke is changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an NaClO 3/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized needle coke is expanded to 6.9 Å with increasing oxygen content. After heating at 200 °C, the oxidized needle coke is reduced to a graphite structure with an inter-layer distance of 3.6 Å. By contrast, a change in the inter-layer distance in KOH-activated needle coke is not observed. An intercalation of pyrolized needle coke, observed on first charge, occurs at 1.0 V. This value is lower than that of KOH-activation needle coke. A capacitor using pyrolized needle coke exhibits a lower internal resistance of 0.57 Ω in 1 kHz, and a larger capacitance per weight and volume of 30.3 F g -1 and 26.9 F ml -1, in the two-electrode system over the potential range 0-2.5 V compared with those of a capacitor using KOH-activation of needle coke. This better electrochemical performance is attributed to a distorted graphene layer structure derived from the process of the inter-layer expansion and shrinkage.

Li15Al3Si6 (Li14.6Al3.4Si6), a compound displaying a heterographite-like anionic framework.

PubMed

Spina, Laurent; Tillard, Monique; Belin, Claude

2003-02-01

The title compound, lithium aluminium silicide (15/3/6), crystallizes in the hexagonal centrosymmetric space group P6(3)/m. The three-dimensional structure of this ternary compound may be depicted as two interpenetrating lattices, namely a graphite-like Li(3)Al(3)Si(6) layer and a distorted diamond-like lithium lattice. As is commonly found for LiAl alloys, the Li and Al atoms are found to share some crystallographic sites. The diamond-like lattice is built up of Li cations, and the graphite-like anionic layer is composed of Si, Al and Li atoms in which Si and Al are covalently bonded [Si-Al = 2.4672 (4) A].

The effect of novel rhenium compounds on lymphosarcoma, PC-3 prostate and myeloid leukemia cancer cell lines and an investigation on the DNA binding properties of one of these compounds through electronic spectroscopy

PubMed Central

Parson, Carl; Smith, Valerie; Krauss, Christopher; Banerjee, Hirendra N.; Reilly, Christopher; Krause, Jeanette A.; Wachira, James M.; Giri, Dipak; Winstead, Angela; Mandal, Santosh K.

2014-01-01

Despite the tremendous success of cisplatin and other platinum-based anticancer drugs, severe toxicity and resistance to tumors limit their applications. It is believed that the coordination (formation of covalent bond) of the metal (platinum) to the nitrogen bases of DNA cause the ruptures of the cancer as well as normal cells. A search for anticancer drugs with different modes of action resulted in the synthesis of variety of novel compounds. Many of them are in clinical trials now. Recently we synthesized a series of novel rhenium pentylcarbonato compounds (PC1–PC6). The rhenium atom in each compound is coordinated (bonded) to a planar polypyridyl aromatic ligand, thereby forcing each compound to intercalate between the DNA bases. We have investigated the DNA binding properties of one of the PC-series of compounds (PC6) using electronic spectroscopy. The UV absorption titration of PC6 with DNA shows hypochromic effect with concomitant bathochromic shift of the charge transfer band at 290 nm. These results suggest that the compound PC6 binds to DNA through intercalation. It is therefore likely that the other PC-series of compounds will behave in a similar manner. Thus it is expected that these compounds will exhibit negligible or no side effect. We have observed that the PC-series of compounds are strong cytotoxic agents against lymphosarcoma (average GI50 ≈ 2±2.6 µM), PC-3 prostate (average GI50 ≈ 3±2.8 µM) and myeloid leukemia (average GI50 ≈ 3±2.8 µM) cancer cell lines. The average GI50 values of the PC-series of compounds are 2–3 less than the corresponding GI50 values of cisplatin. Also each of the PC-series of compounds exhibits less toxicity than cisplatin in the glomerular mesangial cells. PMID:25221731

Separations method for polar molecules

DOEpatents

Thoma, Steven G.; Bonhomme, Francois R.

2004-07-27

A method for separating at least one compound from a liquid mixture containing different compounds where anew crystalline manganese phosphate composition with the formula Mn.sub.3 (PO.sub.4).sub.4.2(H.sub.3 NCH.sub.2 CH.sub.2).sub.3 N.6(H.sub.2 O) is dispersed in the liquid mixture, selectively intercalating one or more compounds into the crystalline structure of the Mn.sub.3 (PO.sub.4).sub.4.2(H.sub.3 NCH.sub.2 CH.sub.2).sub.3 N.6(H.sub.2 O).

Pseudocapacitance of MXene nanosheets for high-power sodium-ion hybrid capacitors

PubMed Central

Wang, Xianfen; Kajiyama, Satoshi; Iinuma, Hiroki; Hosono, Eiji; Oro, Shinji; Moriguchi, Isamu; Okubo, Masashi; Yamada, Atsuo

2015-01-01

High-power Na-ion batteries have tremendous potential in various large-scale applications. However, conventional charge storage through ion intercalation or double-layer formation cannot satisfy the requirements of such applications owing to the slow kinetics of ion intercalation and the small capacitance of the double layer. The present work demonstrates that the pseudocapacitance of the nanosheet compound MXene Ti2C achieves a higher specific capacity relative to double-layer capacitor electrodes and a higher rate capability relative to ion intercalation electrodes. By utilizing the pseudocapacitance as a negative electrode, the prototype Na-ion full cell consisting of an alluaudite Na2Fe2(SO4)3 positive electrode and an MXene Ti2C negative electrode operates at a relatively high voltage of 2.4 V and delivers 90 and 40 mAh g−1 at 1.0 and 5.0 A g−1 (based on the weight of the negative electrode), respectively, which are not attainable by conventional electrochemical energy storage systems. PMID:25832913

Acridine-intercalator based hypoxia selective cytotoxins

DOEpatents

Papadopoulou-Rosenzweig, M.; Bloomer, W.D.

1994-03-15

Hypoxia selective cytotoxins of the general formula STR1 wherein n is from 1 to 5, and NO[sub 2] is in at least one of the 2, 4 or 5-positions of the imidazole are developed. Such compounds have utility as radiosensitizers and chemosensitizers. 9 figs.

c-di-GMP can form remarkably stable G-quadruplexes at physiological conditions in the presence of some planar intercalators.

PubMed

Nakayama, Shizuka; Kelsey, Ilana; Wang, Jingxin; Sintim, Herman O

2011-04-28

The ubiquitous bacterial biofilm regulator, c-di-GMP can form G-quadruplexes at physiological conditions in the presence of some aromatic compounds, such as acriflavine and proflavine. The fluorescence of these compounds is quenched upon c-di-GMP binding and some of the formed c-di-GMP G-quadruplexes are stable even at 75 °C. © The Royal Society of Chemistry 2011

RLE (Research Laboratory of Electronics) Progress Report Number 129.

DTIC Science & Technology

1987-01-01

8217," ’,/’.’t MICROCOP ,"Y RESOLUTION TEST C-’HA"-/’%’.’."."% "-’- -" "."o -- - -" " OI FILE COPYAJ MASSACHUSETTS INSTITUTE OF EHOGYD The RESEARCH LABORATORY of...Intercalation Compound Structures and Transitions .................................. 59 10.0 Semiconductor Surface Studies...understanding of the HEMT, which is the basic block in building surface superlattices on III-V compound materials, our device structure has been simu

Rechargeable lithium battery for use in applications requiring a low to high power output

DOEpatents

Bates, John B.

1996-01-01

Rechargeable lithium batteries which employ characteristics of thin-film batteries can be used to satisfy power requirements within a relatively broad range. Thin-film battery cells utilizing a film of anode material, a film of cathode material and an electrolyte of an amorphorus lithium phosphorus oxynitride can be connected in series or parallel relationship for the purpose of withdrawing electrical power simultaneously from the cells. In addition, such battery cells which employ a lithium intercalation compound as its cathode material can be connected in a manner suitable for supplying power for the operation of an electric vehicle. Still further, by incorporating within the battery cell a relatively thick cathode of a lithium intercalation compound, a relatively thick anode of lithium and an electrolyte film of lithium phosphorus oxynitride, the battery cell is rendered capable of supplying power for any of a number of consumer products, such as a laptop computer or a cellular telephone.

Rechargeable lithium battery for use in applications requiring a low to high power output

DOEpatents

Bates, John B.

1997-01-01

Rechargeable lithium batteries which employ characteristics of thin-film batteries can be used to satisfy power requirements within a relatively broad range. Thin-film battery cells utilizing a film of anode material, a film of cathode material and an electrolyte of an amorphous lithium phosphorus oxynitride can be connected in series or parallel relationship for the purpose of withdrawing electrical power simultaneously from the cells. In addition, such battery cells which employ a lithium intercalation compound as its cathode material can be connected in a manner suitable for supplying power for the operation of an electric vehicle. Still further, by incorporating within the battery cell a relatively thick cathode of a lithium intercalation compound, a relatively thick anode of lithium and an electrolyte film of lithium phosphorus oxynitride, the battery cell is rendered capable of supplying power for any of a number of consumer products, such as a laptop computer or a cellular telephone.

Electronic and total energy properties of ternary and quaternary semiconductor compounds, alloys and superlattices

NASA Technical Reports Server (NTRS)

Lambrecht, Walter R. L.

1992-01-01

This proposal was mainly concerned with the theoretical study of semiconductor compounds, alloys, and superlattices of interest for photovoltaic applications. In the last year (1991) a study was devoted to metal/graphite bonding in relation to use of graphite fiber reinforcement of Cu for high thermal conductivity applications. The main research topics addressed during the full period of the grant are briefly described: studies of the In-Ga-As ternary system; band-offsets at common anion and InAs/GaSb/AlSb heterojunctions; alloy theory (cluster variation method); and Cu/graphite bonding. Most of the work was described more extensively in previous yearly reports and renewal applications and in publications. The last topic is described more fully in a separate report attached. A list of publications resulting directly from this grant or from other grants but related to this work and of conference presentations is given at the end.

Electronic and total energy properties of ternary and quaternary semiconductor compounds, alloys and superlattices

NASA Astrophysics Data System (ADS)

Lambrecht, Walter R. L.

1992-08-01

This proposal was mainly concerned with the theoretical study of semiconductor compounds, alloys, and superlattices of interest for photovoltaic applications. In the last year (1991) a study was devoted to metal/graphite bonding in relation to use of graphite fiber reinforcement of Cu for high thermal conductivity applications. The main research topics addressed during the full period of the grant are briefly described: studies of the In-Ga-As ternary system; band-offsets at common anion and InAs/GaSb/AlSb heterojunctions; alloy theory (cluster variation method); and Cu/graphite bonding. Most of the work was described more extensively in previous yearly reports and renewal applications and in publications. The last topic is described more fully in a separate report attached. A list of publications resulting directly from this grant or from other grants but related to this work and of conference presentations is given at the end.

Fabricating solid carbon porous electrodes from powders

DOEpatents

Kaschmitter, James L.; Tran, Tri D.; Feikert, John H.; Mayer, Steven T.

1997-01-01

Fabrication of conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive dionization, and waste treatment. Electrodes fabricated from low surface area (<50 m.sup.2 /gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon compositives with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to be high surface area carbons, fuel cell electrodes can be produced.

Fabricating solid carbon porous electrodes from powders

DOEpatents

Kaschmitter, J.L.; Tran, T.D.; Feikert, J.H.; Mayer, S.T.

1997-06-10

Fabrication is described for conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive deionization, and waste treatment. Electrodes fabricated from low surface area (<50 m{sup 2}/gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon composites with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to high surface area carbons, fuel cell electrodes can be produced. 1 fig.

A Technique for the Microstructural Examination of Polycrystalline Graphites

DTIC Science & Technology

1959-02-01

dichromate in concentrated phosphoric acid . This etchsnt reacted quite readily with the graphite surface, yet at a rate that was...formation of lamellar compounds, and carbide formation at high temperatues . Of the three classes of reaction, oxidation seems to...reagents and conditions were directed toward preliminary studies of such chemical oxidants as potassium dichromate-phosphoric acid mixtures

Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene

PubMed Central

Shepelev, Olga; Kenig, Samuel

2017-01-01

Impregnation of expandable graphite (EG) after thermal treatment with an epoxy resin containing surface-active agents (SAAs) enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called “stacked” graphene (SG). This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, carbon or glass-fiber-reinforced composites. Several compositions with SAA-modified SG led to higher dynamic moduli especially at high temperatures, reflecting the better wetting ability of the modified nanoparticles. The hydrophilic/hydrophobic nature of the SAA dictates the surface energy balance. More hydrophilic SAAs promoted localization of the SG at the Kevlar/epoxy interface, and morphology seems to be driven by thermodynamics, rather than the kinetic effect of viscosity. This effect was less obvious with carbon or glass fibers, due to the lower surface energy of the carbon fibers or some incompatibility with the glass-fiber sizing. Proper choice of the surfactant and fine-tuning of the crosslink density at the interphase may provide further enhancements in thermo-mechanical behavior. PMID:29046838

Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene.

PubMed

Naveh, Naum; Shepelev, Olga; Kenig, Samuel

2017-01-01

Impregnation of expandable graphite (EG) after thermal treatment with an epoxy resin containing surface-active agents (SAAs) enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called "stacked" graphene (SG). This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, carbon or glass-fiber-reinforced composites. Several compositions with SAA-modified SG led to higher dynamic moduli especially at high temperatures, reflecting the better wetting ability of the modified nanoparticles. The hydrophilic/hydrophobic nature of the SAA dictates the surface energy balance. More hydrophilic SAAs promoted localization of the SG at the Kevlar/epoxy interface, and morphology seems to be driven by thermodynamics, rather than the kinetic effect of viscosity. This effect was less obvious with carbon or glass fibers, due to the lower surface energy of the carbon fibers or some incompatibility with the glass-fiber sizing. Proper choice of the surfactant and fine-tuning of the crosslink density at the interphase may provide further enhancements in thermo-mechanical behavior.

Energy efficient reduced graphene oxide additives: Mechanism of effective lubrication and antiwear properties

PubMed Central

Gupta, Bhavana; Kumar, N.; Panda, Kalpataru; Dash, S.; Tyagi, A. K.

2016-01-01

Optimized concentration of reduced graphene oxide (rGO) in the lube is one of the important factors for effective lubrication of solid body contacts. At sufficiently lower concentration, the lubrication is ineffective and friction/wear is dominated by base oil. In contrast, at sufficiently higher concentration, the rGO sheets aggregates in the oil and weak interlayer sliding characteristic of graphene sheets is no more active for providing lubrication. However, at optimized concentration, friction coefficient and wear is remarkably reduced to 70% and 50%, respectively, as compared to neat oil. Traditionally, such lubrication is described by graphene/graphite particle deposited in contact surfaces that provides lower shear strength of boundary tribofilm. In the present investigation, graphene/graphite tribofilm was absent and existing traditional lubrication mechanism for the reduction of friction and wear is ruled out. It is demonstrated that effective lubrication is possible, if rGO is chemically linked with PEG molecules through hydrogen bonding and PEG intercalated graphene sheets provide sufficiently lower shear strength of freely suspended composite tribofilm under the contact pressure. The work revealed that physical deposition and adsorption of the graphene sheets in the metallic contacts is not necessary for the lubrication. PMID:26725334

Influence of electrolytes (TEABF4 and TEMABF4) on electrochemical performance of graphite oxide derived from needle coke.

PubMed

Yang, Sunhye; Kim, Ick-Jun; Choi, In-Sik; Bae, Mi-Kyeong; Kim, Hyun-Soo

2013-05-01

The structure of needle coke was changed to graphite oxide structure after oxidation treatment with 70 wt.% of nitric acid and sodium chlorate (NaClO3), and the inter-layer distance of the oxidized needle coke was expanded to 6.9 angstroms. The first charge profile of the oxidized needle coke-cell with 1.2 M TEMABF4/acetonitrile solution displayed that the intercalation of electrolyte ions into the inter-layer occurred at 1.0 V, which value is lower than 1.3 V of the oxidized needle coke-cell with 1.2 M TEABF4/acetonitrile solution. After first charge/discharge, the cell using TEMABF4 electrolyte exhibited smaller electrode resistance of 0.05 omega, and larger specific volume capacitance of 25.5 F/ml at the two-electrode system in the potential range 0-2.5 V than those of the cell using TEABF4 electrolyte. Compared to the TEABF4 electrolyte, better electrochemical performance of the TEMABF4 electrolyte in the oxidized needle coke may be caused by the smaller cation (TEMA+) size and better ion mobility in the nanopores between inter-layers.

Designed synergetic effect of electrolyte additives to improve interfacial chemistry of MCMB electrode in propylene carbonate-based electrolyte for enhanced low and room temperature performance.

PubMed

Wotango, Aselefech Sorsa; Su, Wei-Nien; Haregewoin, Atetegeb Meazah; Chen, Hung-Ming; Cheng, Ju-Hsiang; Lin, Ming-Hsien; Wang, Chia-Hsin; Hwang, Bing-Joe

2018-05-09

The performance of lithium ion batteries rapidly falls at lower temperatures due to decreasing conductivity of electrolytes and Solid Electrolyte Interphase (SEI) on graphite anode. Hence, it limits the practical use of lithium ion batteries at sub-zero temperatures and also affects the development of lithium ion batteries for widespread applications. The SEI formed on the graphite surface is very influential in determining the performance of the battery. Herein, a new electrolyte additive, 4-Chloromethyl-1,3,2-dioxathiolane-2-oxide (CMDO), is prepared to improve the properties of commonly used electrolyte constituents - ethylene carbonate (EC), and fluoroethylene carbonate (FEC). The formation of an efficient passivation layer in propylene carbonate (PC) -based electrolyte for MCMB electrode was investigated. The addition of CMDO resulted in a much less irreversible capacity loss and induces thin SEI formation. However, the combination of the three additives played a key role to enhance reversible capacity of MCMB electrode at lower or ambient temperature. The electrochemical measurement analysis showed that the SEI formed from a mixture of the three additives gave better intercalation-deintercalation of lithium ions.

Modeling of surface temperature effects on mixed material migration in NSTX-U

NASA Astrophysics Data System (ADS)

Nichols, J. H.; Jaworski, M. A.; Schmid, K.

2016-10-01

NSTX-U will initially operate with graphite walls, periodically coated with thin lithium films to improve plasma performance. However, the spatial and temporal evolution of these films during and after plasma exposure is poorly understood. The WallDYN global mixed-material surface evolution model has recently been applied to the NSTX-U geometry to simulate the evolution of poloidally inhomogenous mixed C/Li/O plasma-facing surfaces. The WallDYN model couples local erosion and deposition processes with plasma impurity transport in a non-iterative, self-consistent manner that maintains overall material balance. Temperature-dependent sputtering of lithium has been added to WallDYN, utilizing an adatom sputtering model developed from test stand experimental data. Additionally, a simplified temperature-dependent diffusion model has been added to WallDYN so as to capture the intercalation of lithium into a graphite bulk matrix. The sensitivity of global lithium migration patterns to changes in surface temperature magnitude and distribution will be examined. The effect of intra-discharge increases in surface temperature due to plasma heating, such as those observed during NSTX Liquid Lithium Divertor experiments, will also be examined. Work supported by US DOE contract DE-AC02-09CH11466.

The Discovery and Characterization of the Carbon Allotrope GUITAR

NASA Astrophysics Data System (ADS)

Foutch, Jeremy D.

GUITAR (Graphene from the University of Idaho Thermolyzed Asphalt Reaction) was first observed as a silvery deposit on the inside of a porcelain crucible after the pyrolysis of oil shale during a routine metals analysis. After initial characterization by optical and electron microscopies it was thought to be multi-layered graphene or graphene paper. Raman spectrographic analysis indicated that it was a nano-crystalline graphite or graphene. Electrochemical characterization showed three significant differences from graphene or graphite; (1) There is lack of electrolyte intercalation through basal plane and edge planes of GUITAR, (2) there is fast heterogenous electron transfer at both the basal plane as well as the edge plane and (3) the hydrogen overpotential is much higher. In this work, GUITAR was subjected to a battery of techniques to more fully characterize its composition, morphology, and structure. Based on the results obtained, it is proposed that GUITAR is a highly noble, porous material, consisting of nanometer-sized grains of two-dimensional graphene-like layers, which are interconnected by three-dimensional diamond-like “defects.” This unique structure begins to give some explanation as to why GUITAR displays many of the useful and superior qualities of both graphene and diamond.

The application of phase contrast X-ray techniques for imaging Li-ion battery electrodes

NASA Astrophysics Data System (ADS)

Eastwood, D. S.; Bradley, R. S.; Tariq, F.; Cooper, S. J.; Taiwo, O. O.; Gelb, J.; Merkle, A.; Brett, D. J. L.; Brandon, N. P.; Withers, P. J.; Lee, P. D.; Shearing, P. R.

2014-04-01

In order to accelerate the commercialization of fuel cells and batteries across a range of applications, an understanding of the mechanisms by which they age and degrade at the microstructural level is required. Here, the most widely commercialized Li-ion batteries based on porous graphite based electrodes which de/intercalate Li+ ions during charge/discharge are studied by two phase contrast enhanced X-ray imaging modes, namely in-line phase contrast and Zernike phase contrast at the micro (synchrotron) and nano (laboratory X-ray microscope) level, respectively. The rate of charge cycling is directly dependent on the nature of the electrode microstructure, which are typically complex multi-scale 3D geometries with significant microstructural heterogeneities. We have been able to characterise the porosity and the tortuosity by micro-CT as well as the morphology of 5 individual graphite particles by nano-tomography finding that while their volume varied significantly their sphericity was surprisingly similar. The volume specific surface areas of the individual grains measured by nano-CT are significantly larger than the total volume specific surface area of the electrode from the micro-CT imaging, which can be attributed to the greater particle surface area visible at higher resolution.

Towards efficient solar hydrogen production by intercalated carbon nitride photocatalyst.

PubMed

Gao, Honglin; Yan, Shicheng; Wang, Jiajia; Huang, Yu An; Wang, Peng; Li, Zhaosheng; Zou, Zhigang

2013-11-07

The development of efficient photocatalytic material for converting solar energy to hydrogen energy as viable alternatives to fossil-fuel technologies is expected to revolutionize energy shortage and environment issues. However, to date, the low quantum yield for solar hydrogen production over photocatalysts has hindered advances in the practical applications of photocatalysis. Here, we show that a carbon nitride intercalation compound (CNIC) synthesized by a simple molten salt route is an efficient polymer photocatalyst with a high quantum yield. We found that coordinating the alkali metals into the C-N plane of carbon nitride will induce the un-uniform spatial charge distribution. The electrons are confined in the intercalated region while the holes are in the far intercalated region, which promoted efficient separation of photogenerated carriers. The donor-type alkali metal ions coordinating into the nitrogen pots of carbon nitrides increase the free carrier concentration and lead to the formation of novel nonradiative paths. This should favor improved transport of the photogenerated electron and hole and decrease the electron-hole recombination rate. As a result, the CNIC exhibits a quantum yield as high as 21.2% under 420 nm light irradiation for solar hydrogen production. Such high quantum yield opens up new opportunities for using cheap semiconducting polymers as energy transducers.

SUPPRESSION OF HUMORAL IMMUNE RESPONSES BY 2,3,7,8-TETRACHLORODIBENZO-p-DIOXIN INTERCALATED IN SMECTITE CLAY

PubMed Central

Boyd, Stephen A.; Johnston, Cliff T.; Pinnavaia, Thomas J.; Kaminski, Norbert E.; Teppen, Brian J.; Li, Hui; Khan, Bushra; Crawford, Robert B.; Kovalova, Natalia; Kim, Seong-Su; Shao, Hua; Gu, Cheng; Kaplan, Barbara L.F.

2018-01-01

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a highly toxic environmental contaminant found in soils and sediments. Because of its exceptionally low water solubility, this compound exists predominantly in the sorbed state in natural environments. Clay minerals, especially expandable smectite clays, are one of the major component geosorbents in soils and sediments that can function as an effective adsorbent for environmental dioxins, including TCDD. In this study, TCDD was intercalated in the smectite clay saponite by an incipient wetness method. The primary goal of this study was to intercalate TCDD in natural K-saponite clay and evaluate its immunotoxic effects in vivo. The relative bioavailability of TCDD was evaluated by comparing the metabolic activity of TCDD administered in the adsorbed state as an intercalate in saponite and freely dissolved in corn oil. This comparison revealed nearly identical TCDD-induced suppression of humoral immunity, a well-established and sensitive sequela, in a mammalian (mouse) model. This result suggests that TCDD adsorbed by clays is likely to be available for biouptake and biodistribution in mammals, consistent with previous observations of TCDD in livestock exposed to dioxin-contaminated ball clays that were used as feed additives. Adsorption of TCDD by clay minerals does not appear to mitigate risk associated with TCDD exposure substantially. PMID:21994089

Electrochemical-mechanical coupled modeling and parameterization of swelling and ionic transport in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Sauerteig, Daniel; Hanselmann, Nina; Arzberger, Arno; Reinshagen, Holger; Ivanov, Svetlozar; Bund, Andreas

2018-02-01

The intercalation and aging induced volume changes of lithium-ion battery electrodes lead to significant mechanical pressure or volume changes on cell and module level. As the correlation between electrochemical and mechanical performance of lithium ion batteries at nano and macro scale requires a comprehensive and multidisciplinary approach, physical modeling accounting for chemical and mechanical phenomena during operation is very useful for the battery design. Since the introduced fully-coupled physical model requires proper parameterization, this work also focuses on identifying appropriate mathematical representation of compressibility as well as the ionic transport in the porous electrodes and the separator. The ionic transport is characterized by electrochemical impedance spectroscopy (EIS) using symmetric pouch cells comprising LiNi1/3Mn1/3Co1/3O2 (NMC) cathode, graphite anode and polyethylene separator. The EIS measurements are carried out at various mechanical loads. The observed decrease of the ionic conductivity reveals a significant transport limitation at high pressures. The experimentally obtained data are applied as input to the electrochemical-mechanical model of a prismatic 10 Ah cell. Our computational approach accounts intercalation induced electrode expansion, stress generation caused by mechanical boundaries, compression of the electrodes and the separator, outer expansion of the cell and finally the influence of the ionic transport within the electrolyte.

Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

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

Doe, Robert E.; Downie, Craig M.; Fischer, Christopher

2016-01-19

Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqueous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negativemore » electrode active material is described.« less

Evidences for dry deintercalation in layered compounds upon controlled surface charging in x-ray photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Feldman, Y.; Zak, A.; Tenne, R.; Cohen, H.

2003-09-01

Pronounced surface diffusion is observed during x-ray photoelectron spectroscopy measurements of 2H platelets and inorganic fullerene-like (IF) MS2 (M=W,Mo) powders, intercalated with alkaline (A=K,Na) elements. Using controlled surface charging the intercalants migrate towards the surface, where they oxidize. This dry deintercalation is controllable via external charging parameters, yet showing that internal chemical and structural parameters play an important role in the process. Diffusion rates out of 2H matrixes are generally higher than in corresponding IF samples. Clear differences are also found between Mo and W-based systems. Application of this approach into surface modification and processing is proposed.

Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

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

Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher

2016-07-26

Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqueous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negativemore » electrode active material is described.« less

Use of a heated graphite scrubber as a means of reducing interferences in UV-absorbance measurements of atmospheric ozone

NASA Astrophysics Data System (ADS)

Turnipseed, Andrew A.; Andersen, Peter C.; Williford, Craig J.; Ennis, Christine A.; Birks, John W.

2017-06-01

A new solid-phase scrubber for use in conventional ozone (O3) photometers was investigated as a means of reducing interferences from other UV-absorbing species and water vapor. It was found that when heated to 100-130 °C, a tubular graphite scrubber efficiently removed up to 500 ppb ozone and ozone monitors using the heated graphite scrubber were found to be less susceptible to interferences from water vapor, mercury vapor, and aromatic volatile organic compounds (VOCs) compared to conventional metal oxide scrubbers. Ambient measurements from a graphite scrubber-equipped photometer and a co-located Federal equivalent method (FEM) ozone analyzer showed excellent agreement over 38 days of measurements and indicated no loss in the scrubber's ability to remove ozone when operated at 130 °C. The use of a heated graphite scrubber was found to reduce the interference from mercury vapor to ≤ 3 % of that obtained using a packed-bed Hopcalite scrubber. For a series of substituted aromatic compounds (ranging in volatility and absorption cross section at 253.7 nm), the graphite scrubber was observed to consistently exhibit reduced levels of interference, typically by factors of 2.5 to 20 less than with Hopcalite. Conventional solid-phase scrubbers also exhibited complex VOC adsorption and desorption characteristics that were dependent upon the relative humidity (RH), volatility of the VOC, and the available surface area of the scrubber. This complex behavior involving humidity is avoided by use of a heated graphite scrubber. These results suggest that heated graphite scrubbers could be substituted in most ozone photometers as a means of reducing interferences from other UV-absorbing species found in the atmosphere. This could be particularly important in ozone monitoring for compliance with the United States (U.S.) Clean Air Act or for use in VOC-rich environments such as in smog chambers and monitoring indoor air quality.

Synthesis of Graphite Oxide with Different Surface Oxygen Contents Assisted Microwave Radiation

PubMed Central

Ibarra-Hernández, Adriana

2018-01-01

Graphite oxide is synthesized via oxidation reaction using oxidant compounds that have lattice defects by the incorporation of unlike functional groups. Herein, we report the synthesis of the graphite oxide with diverse surface oxygen content through three (B, C, D) different modified versions of the Hummers method assisted microwave radiation compared with the conventional graphite oxide sample obtained by Hummers method (A). These methods allow not only the production of graphite oxide but also reduced graphene oxide, without undergoing chemical, thermal, or mechanical reduction steps. The values obtained of C/O ratio were ~2, 3.4, and ~8.5 for methodologies C, B, and D, respectively, indicating the presence of graphite oxide and reduced graphene oxide, according to X-ray photoelectron spectroscopy. Raman spectroscopy of method D shows the fewest structural defects compared to the other methodologies. The results obtained suggest that the permanganate ion produces reducing species during graphite oxidation. The generation of these species is attributed to a reversible reaction between the permanganate ion with π electrons, ions, and radicals produced after treatment with microwave radiation. PMID:29438280

Synthesis, crystal structure, DFT calculation and DNA binding studies of new water-soluble derivatives of dppz

NASA Astrophysics Data System (ADS)

Aminzadeh, Mohammad; Eslami, Abbas; Kia, Reza; Aleeshah, Roghayeh

2017-10-01

Diquaternarization of dipyrido-[2,3-a:2‧,3‧-c]-phenazine,(dppz) and its analogous dipyrido-[2,3-a:2‧,3‧-c]-dimethylphenazine,(dppx) using 1,3-dibromopropane afford new water-soluble derivatives of phenazine, propylene-bipyridyldiylium-phenazine (1) and propylene-bipyridyldiylium-dimethylphenazine (2). The compounds have been characterized by means of FT-IR, NMR, elemental analysis and conductometric measurements and their structure were determined by X-ray crystallography. The experimental studies on the compounds have been accompanied computationally by Density Functional Theory (DFT) calculations. The DNA binding properties of both compounds to calf thymus DNA (ctDNA) were investigated by UV-Vis absorption and emission methods. The expanded UV-Vis spectral data matrix was analyzed by multivariate curve resolution-alternating least squares (MCR-ALS) technique to obtain the concentration profile and pure spectra of all reaction species which existed in the interaction procedure. Multivariate curve resolution may help us to give a better understanding of the 1(Cl)2-ctDNA and 2(Cl)2-ctDNA interaction mechanism. The results suggest that both compounds bind tightly to DNA through intercalation mechanism and the DNA binding affinity of 2 is slightly lower than that of 1 due to steric hindrance of the methyl group. Also, thermal denaturation studies reveal that these compounds show strong affinity for binding with calf thymus DNA. The thermodynamic parameters of the DNA binding process were obtained from the temperature dependence of the binding constants and the results showed that binding of both compounds to DNA is an enthalpically driven process that is in agreement with proposed DNA intercalation capability of these compounds.

Recompressed exfoliated graphite articles

DOEpatents

Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

2013-08-06

This invention provides an electrically conductive, less anisotropic, recompressed exfoliated graphite article comprising a mixture of (a) expanded or exfoliated graphite flakes; and (b) particles of non-expandable graphite or carbon, wherein the non-expandable graphite or carbon particles are in the amount of between about 3% and about 70% by weight based on the total weight of the particles and the expanded graphite flakes combined; wherein the mixture is compressed to form the article having an apparent bulk density of from about 0.1 g/cm.sup.3 to about 2.0 g/cm.sup.3. The article exhibits a thickness-direction conductivity typically greater than 50 S/cm, more typically greater than 100 S/cm, and most typically greater than 200 S/cm. The article, when used in a thin foil or sheet form, can be a useful component in a sheet molding compound plate used as a fuel cell separator or flow field plate. The article may also be used as a current collector for a battery, supercapacitor, or any other electrochemical cell.

Graphene oxide and H2 production from bioelectrochemical graphite oxidation.

PubMed

Lu, Lu; Zeng, Cuiping; Wang, Luda; Yin, Xiaobo; Jin, Song; Lu, Anhuai; Jason Ren, Zhiyong

2015-11-17

Graphene oxide (GO) is an emerging material for energy and environmental applications, but it has been primarily produced using chemical processes involving high energy consumption and hazardous chemicals. In this study, we reported a new bioelectrochemical method to produce GO from graphite under ambient conditions without chemical amendments, value-added organic compounds and high rate H2 were also produced. Compared with abiotic electrochemical electrolysis control, the microbial assisted graphite oxidation produced high rate of graphite oxide and graphene oxide (BEGO) sheets, CO2, and current at lower applied voltage. The resultant electrons are transferred to a biocathode, where H2 and organic compounds are produced by microbial reduction of protons and CO2, respectively, a process known as microbial electrosynthesis (MES). Pseudomonas is the dominant population on the anode, while abundant anaerobic solvent-producing bacteria Clostridium carboxidivorans is likely responsible for electrosynthesis on the cathode. Oxygen production through water electrolysis was not detected on the anode due to the presence of facultative and aerobic bacteria as O2 sinkers. This new method provides a sustainable route for producing graphene materials and renewable H2 at low cost, and it may stimulate a new area of research in MES.

Graphene oxide and H2 production from bioelectrochemical graphite oxidation

PubMed Central

Lu, Lu; Zeng, Cuiping; Wang, Luda; Yin, Xiaobo; Jin, Song; Lu, Anhuai; Jason Ren, Zhiyong

2015-01-01

Graphene oxide (GO) is an emerging material for energy and environmental applications, but it has been primarily produced using chemical processes involving high energy consumption and hazardous chemicals. In this study, we reported a new bioelectrochemical method to produce GO from graphite under ambient conditions without chemical amendments, value-added organic compounds and high rate H2 were also produced. Compared with abiotic electrochemical electrolysis control, the microbial assisted graphite oxidation produced high rate of graphite oxide and graphene oxide (BEGO) sheets, CO2, and current at lower applied voltage. The resultant electrons are transferred to a biocathode, where H2 and organic compounds are produced by microbial reduction of protons and CO2, respectively, a process known as microbial electrosynthesis (MES). Pseudomonas is the dominant population on the anode, while abundant anaerobic solvent-producing bacteria Clostridium carboxidivorans is likely responsible for electrosynthesis on the cathode. Oxygen production through water electrolysis was not detected on the anode due to the presence of facultative and aerobic bacteria as O2 sinkers. This new method provides a sustainable route for producing graphene materials and renewable H2 at low cost, and it may stimulate a new area of research in MES. PMID:26573014

Preparation and properties of recycled HDPE/clay hybrids

Treesearch

Yong Lei; Qinglin Wu; Craig M. Clemons

2007-01-01

Hybrids based on recycled high density polyethylene (RHDPE) and organic clay were made by melt compounding. The influence of blending method, compatibilizers, and clay content on clay intercalation and exfoliation, RHDPE crystallization behavior, and the mechanical properties of RHDPE/clay hybrids were investigated. Both maleated polyethylene (MAPE) and titanate could...

Interaction of indole-papaverine with DNA in solutions of various ionic strength

NASA Astrophysics Data System (ADS)

Travkina, V. I.; Moroshkina, E. B.; Osinnikova, D. N.

2017-11-01

Interaction of synthetic alkaloid of isoquinoline series, which is an analogue of the biologically active compound papaverine, was studied by spectral, microcalorimetric, optical and hydrodynamic methods at different ionic strengths of medium. It was found that the investigated compound may interact with DNA in various ways depending on the ratio of ligand - DNA concentrations and ionic strength of solution (μ). When μ = 0.001, indole-papaverine intercalates into the double helix of DNA. The increase of μ resulted in a decrease of the affinity of the compound to DNA and a change its binding method.

Analysis of vibrational response in graphite oxide nanoplatelets

NASA Astrophysics Data System (ADS)

Prias Barragan, Jhon Jairo; Gross, Katherine; Lajaunie, Luc; Arenal, Raul; Ariza Calderon, Hernando; Prieto, Pedro

In this work, we present a new low-cost fabrication process to obtain graphite oxide nanoplatelets from bamboo pyroligneous acid (GO-BPA) by thermal decomposition method using a pyrolysis system for different carbonization temperatures from 673 to 973 K. The GO-BPA samples were characterized by using Raman, FTIR, XRD, SEM and TEM techniques, whose results suggest that increased carbonization temperature increases graphite conversion, boundary defects, desorption of some organic compounds and phonon response, respectively. We discuss potential applications of the GO-BPA samples involving phonon response that would benefit from a fully scaled technology, advanced electronic sensors and devices.

Metal complexes as DNA intercalators.

PubMed

Liu, Hong-Ke; Sadler, Peter J

2011-05-17

DNA has a strong affinity for many heterocyclic aromatic dyes, such as acridine and its derivatives. Lerman in 1961 first proposed intercalation as the source of this affinity, and this mode of DNA binding has since attracted considerable research scrutiny. Organic intercalators can inhibit nucleic acid synthesis in vivo, and they are now common anticancer drugs in clinical therapy. The covalent attachment of organic intercalators to transition metal coordination complexes, yielding metallointercalators, can lead to novel DNA interactions that influence biological activity. Metal complexes with σ-bonded aromatic side arms can act as dual-function complexes: they bind to DNA both by metal coordination and through intercalation of the attached aromatic ligand. These aromatic side arms introduce new modes of DNA binding, involving mutual interactions of functional groups held in close proximity. The biological activity of both cis- and trans-diamine Pt(II) complexes is dramatically enhanced by the addition of σ-bonded intercalators. We have explored a new class of organometallic "piano-stool" Ru(II) and Os(II) arene anticancer complexes of the type [(η(6)-arene)Ru/Os(XY)Cl](+). Here XY is, for example, ethylenediamine (en), and the arene ligand can take many forms, including tetrahydroanthracene, biphenyl, or p-cymene. Arene-nucleobase stacking interactions can have a significant influence on both the kinetics and thermodynamics of DNA binding. In particular, the cytotoxic activity, conformational distortions, recognition by DNA-binding proteins, and repair mechanisms are dependent on the arene. A major difficulty in developing anticancer drugs is cross-resistance, a phenomenon whereby a cell that is resistant to one drug is also resistant to another drug in the same class. These new complexes are non-cross-resistant with cisplatin towards cancer cells: they constitute a new class of anticancer agents, with a mechanism of action that differs from the anticancer drug cisplatin and its analogs. The Ru-arene complexes with dual functions are more potent towards cancer cells than their nonintercalating analogs. In this Account, we focus on recent studies of dual-function organometallic Ru(II)- and Os(II)-arene complexes and the methods used to detect arene-DNA intercalation. We relate these interactions to the mechanism of anticancer activity and to structure-activity relationships. The interactions between these complexes and DNA show close similarities to those of covalent polycyclic aromatic carcinogens, especially to N7-alkylating intercalation compounds. However, Ru-arene complexes exhibit some new features. Classical intercalation and base extrusion next to the metallated base is observed for {(η(6)-biphenyl)Ru(ethylenediamine)}(2+) adducts of a 14-mer duplex, while penetrating arene intercalation occurs for adducts of the nonaromatic bulky intercalator {(η(6)-tetrahydroanthracene)Ru(ethylenediamine)}(2+) with a 6-mer duplex. The introduction of dual-function Ru-arene complexes introduces new mechanisms of antitumor activity, novel mechanisms for attack on DNA, and new concepts for developing structure- activity relationships. We hope this discussion will stimulate thoughtful and focused research on the design of anticancer chemotherapeutic agents using these unique approaches.

Unifying Principles of the Reductive Covalent Graphene Functionalization.

PubMed

Abellán, Gonzalo; Schirowski, Milan; Edelthalhammer, Konstantin F; Fickert, Michael; Werbach, Katharina; Peterlik, Herwig; Hauke, Frank; Hirsch, Andreas

2017-04-12

Covalently functionalized graphene derivatives were synthesized via benchmark reductive routes using graphite intercalation compounds (GICs), in particular KC 8 . We have compared the graphene arylation and alkylation of the GIC using 4-tert-butylphenyldiazonium and bis(4-(tert-butyl)phenyl)iodonium salts, as well as phenyl iodide, n-hexyl iodide, and n-dodecyl iodide, as electrophiles in model reactions. We have put a particular focus on the evaluation of the degree of addition and the bulk functionalization homogeneity (H bulk ). For this purpose, we have employed statistical Raman spectroscopy (SRS), and a forefront characterization tool using thermogravimetric analysis coupled with FT-IR, gas chromatography, and mass spectrometry (TGA/FT-IR/GC/MS). The present study unambiguously shows that the graphene functionalization using alkyl iodides leads to the best results, in terms of both the degree of addition and the H bulk . Moreover, we have identified the reversible character of the covalent addition chemistry, even at temperatures below 200 °C. The thermally induced addend cleavage proceeds homolytically, which allows for the detection of dimeric cleavage products by TGA/FT-IR/GC/MS. This dimerization points to a certain degree of regioselectivity, leading to a low sheet homogeneity (H sheet ). Finally, we developed this concept by performing the reductive alkylation reaction in monolayer CVD graphene films. This work provides important insights into the understanding of basic principles of reductive graphene functionalization and will serve as a guide in the design of new graphene functionalization concepts.

Intercalated organic-inorganic perovskites stabilized by fluoroaryl-aryl interactions.

PubMed

Mitzi, David B; Medeiros, David R; Malenfant, Patrick R L

2002-04-22

Crystals of several new hybrid tin(II) iodide-based perovskites, involving 2,3,4,5,6- pentafluorophenethylammonium or phenethylammonium cation bilayers and intercalated aryl or perfluoroaryl molecules, were grown by slow evaporation of a methanol solution containing the hybrid perovskite and the intercalating species. The (C(6)F(5)C(2)H(4)NH(3))(2)SnI(4).(C(6)H(6)) structure was solved at -75 degrees C in a monoclinic C2/c subcell [a = 41.089(12) A, b = 6.134(2) A, c = 12.245(3) A, beta = 94.021(5) degrees, Z = 4] and consists of sheets of corner-sharing distorted SnI(6) octahedra separated by bilayers of pentafluorophenethylammonium cations. The intercalated benzene molecules form a single well-ordered layer interposed between adjacent fluoroaryl cation layers. The corresponding hybrid with an unfluorinated organic cation and fluorinated intercalating molecule, (C(6)H(5)C(2)H(4)NH(3))(2)SnI(4).(C(6)F(6)), is isostructural [a = 40.685(4) A, b = 6.0804(6) A, c = 12.163(1) A, beta = 93.136(2) degrees, Z = 4]. For each intercalated system, close C...C contacts (3.44-3.50 A) between the aromatic cation and the intercalated molecule are indicative of a significant face-to-face interaction, similar to that found in the complex C(6)H(6).C(6)F(6). Crystal growth runs with the organic cation and prospective intercalating molecule either both fluorinated or both unfluorinated did not yield stable intercalated compounds, demonstrating the significance of fluoroaryl-aryl interactions in the current intercalated structures. Thermal analysis of (C(6)F(5)C(2)H(4)NH(3))(2)SnI(4).(C(6)H(6)) and (C(6)H(5)C(2)H(4)NH(3))(2)SnI(4).(C(6)F(6)) crystals yields, in addition to the characteristic transitions of the parent perovskite, endothermic transitions [12.6(5) and 32.1(8) kJ/mol, respectively] with an onset at 145 degrees C and a weight loss corresponding to the complete loss of the intercalated molecule. The relatively high deintercalation temperature (well above the boiling point of benzene and hexafluorobenzene) demonstrates the usefulness of the hybrid perovskites in providing a stable framework for the examination of the fluoroaryl-aryl interaction, as well as the potential importance of this interaction in tailoring new hybrid perovskites. UV-vis absorption measurements on (C(6)H(5)C(2)H(4)NH(3))(2)SnI(4).(C(6)F(6)) thin films indicate a small reversible wavelength shift to higher energy for the tin(II) iodide framework exciton peak (with respect to that of the parent perovskite spectrum), from 608(2) nm [2.04 eV] to 595(2) nm [2.08 eV], and a corresponding shift in the band edge position. This spectral shift can most reasonably be attributed to subtle structural changes induced in the tin(II) iodide sheets by the intercalated hexafluorobenzene molecules.

Multiply Intercalator-Substituted Cu(II) Cyclen Complexes as DNA Condensers and DNA/RNA Synthesis Inhibitors.

PubMed

Hormann, Jan; Malina, Jaroslav; Lemke, Oliver; Hülsey, Max J; Wedepohl, Stefanie; Potthoff, Jan; Schmidt, Claudia; Ott, Ingo; Keller, Bettina G; Brabec, Viktor; Kulak, Nora

2018-05-07

Many drugs that are applied in anticancer therapy such as the anthracycline doxorubicin contain DNA-intercalating 9,10-anthraquinone (AQ) moieties. When Cu(II) cyclen complexes were functionalized with up to three (2-anthraquinonyl)methyl substituents, they efficiently inhibited DNA and RNA synthesis resulting in high cytotoxicity (selective for cancer cells) accompanied by DNA condensation/aggregation phenomena. Molecular modeling suggests an unusual bisintercalation mode with only one base pair between the two AQ moieties and the metal complex as a linker. A regioisomer, in which the AQ moieties point in directions unfavorable for such an interaction, had a much weaker biological activity. The ligands alone and corresponding Zn(II) complexes (used as redox inert control compounds) also exhibited lower activity.

Discrete Li-occupation versus pseudo-continuous Na-occupation and their relationship with structural change behaviors in Fe₂(MoO₄)₃

DOE PAGES

Yue, Ji-Li; Zhou, Yong-Ning; Shi, Si-Qi; ...

2015-03-06

The key factors governing the single-phase or multi-phase structural change behaviors during the intercalation/deintercalation of guest ions have not been well studied and understood yet. Through systematic studies of orthorhombic Fe₂(MoO₄)₃ electrode, two distinct guest ion occupation paths, namely discrete one for Li and pseudo-continuous one for Na, as well as their relationship with single-phase and two-phase modes for Na⁺ and Li⁺, respectively during the intercalation/deintercalation process have been demonstrated. For the first time, the direct atomic-scale observation of biphasic domains (discrete occupation) in partially lithiated Fe₂(MoO₄)₃ and the one by one Na occupation (pseudo-continuous occupation) at 8d sites inmore » partially sodiated Fe₂(MoO₄)₃ are obtained during the discharge processes of Li/Fe₂(MoO₄)₃ and Na/Fe₂(MoO₄)₃ cells respectively. Our combined experimental and theoretical studies bring the new insights for the research and development of intercalation compounds as electrode materials for secondary batteries.« less

Superconducting critical fields of alkali and alkaline-earth intercalates of MoS2

NASA Technical Reports Server (NTRS)

Woollam, J. A.; Somoano, R. B.

1976-01-01

Results are reported for measurements of the critical-field anisotropy and temperature dependence of group-VIB semiconductor MoS2 intercalated with the alkali and alkaline-earth metals Na, K, Rb, Cs, and Sr. The temperature dependences are compared with present theories on the relation between critical field and transition temperature in the clean and dirty limits over the reduced-temperature range from 1 to 0.1. The critical-field anisotropy data are compared with predictions based on coupled-layers and thin-film ('independent-layers') models. It is found that the critical-field boundaries are steep in all cases, that the fields are greater than theoretical predictions at low temperatures, and that an unusual positive curvature in the temperature dependence appears which may be related to the high anisotropy of the layer structure. The results show that materials with the largest ionic intercalate atom diameters and hexagonal structures (K, Rb, and Cs compounds) have the highest critical temperatures, critical fields, and critical-boundary slopes; the critical fields of these materials are observed to exceed the paramagnetic limiting fields.

Formation of mixed-layer structures in smectites intercalated with tryptone

NASA Astrophysics Data System (ADS)

Block, K. A.; Trusiak, A.; Steiner, J. C.; Katz, A.; Gottlieb, P.; Alimova, A.

2012-12-01

Stable clay-protein complexes are fundamental to studies of the critical zone, terrestrial ecosystems, pharmacology, and industrial applications such as bioremediation. Two sets of montmorillonite clays were purified and made homoionic for Na and Mg. Mg-montmorillonite and Na-montmorillonite were mixed with tryptone (casein digest) in a 9:1 and 18:1 clay:tryptone ratio, resulting in the formation of reversible intercalated structures. X-ray diffraction analysis of the protein-clay complexes produced profiles consisting of two peaks associated with the smectite 001 reflection and a related tryptone-packet peak similar to that produced by a mixed layer clay structure. Shifts in the 002, 003, and 004 diffraction maxima are attributed to disorder caused by the interaction with the protein. Line broadening in the smectite-tryptone XRD spectra is interpreted to be the result of interlayer absorption. Adsorption produces coherent crystalline packets of regularly interbedded tryptone and smectite platelets. SEM images reveal clay platelets with upwardly rolled edges that tend toward cylindrical structures with the production of occasional tubes in the smaller platelet size range as noted for organic compound-kaolinite intercalation reported by Fenoll Hach-Ali and Weiss (1969). Reference: Fenoll Hach-Ali, P.F., Weiss, A., 1969. Estudio de la reaccion de caolinita y N-metilform- amida. Quimica LXV, 769-790. Scanning electron micrograph of tryptone-intercalated clay platelets exhibiting rolled edge structure.

Suppression of humoral immune responses by 2,3,7,8-tetrachlorodibenzo-p-dioxin intercalated in smectite clay.

PubMed

Boyd, Stephen A; Johnston, Cliff T; Pinnavaia, Thomas J; Kaminski, Norbert E; Teppen, Brian J; Li, Hui; Khan, Bushra; Crawford, Robert B; Kovalova, Natalia; Kim, Seong-Su; Shao, Hua; Gu, Cheng; Kaplan, Barbara L F

2011-12-01

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a highly toxic environmental contaminant found in soils and sediments. Because of its exceptionally low water solubility, this compound exists predominantly in the sorbed state in natural environments. Clay minerals, especially expandable smectite clays, are one of the major component geosorbents in soils and sediments that can function as an effective adsorbent for environmental dioxins, including TCDD. In this study, TCDD was intercalated in the smectite clay saponite by an incipient wetness method. The primary goal of this study was to intercalate TCDD in natural K-saponite clay and evaluate its immunotoxic effects in vivo. The relative bioavailability of TCDD was evaluated by comparing the metabolic activity of TCDD administered in the adsorbed state as an intercalate in saponite and freely dissolved in corn oil. This comparison revealed nearly identical TCDD-induced suppression of humoral immunity, a well-established and sensitive sequela, in a mammalian (mouse) model. This result suggests that TCDD adsorbed by clays is likely to be available for biouptake and biodistribution in mammals, consistent with previous observations of TCDD in livestock exposed to dioxin-contaminated ball clays that were used as feed additives. Adsorption of TCDD by clay minerals does not appear to mitigate risk associated with TCDD exposure substantially. Copyright © 2011 SETAC.

Adsorption and regeneration of expanded graphite modified by CTAB-KBr/H3PO4 for marine oil pollution.

PubMed

Xu, Congbin; Jiao, Chunlei; Yao, Ruihua; Lin, Aijun; Jiao, Wentao

2018-02-01

The cleaning-up of viscous oil spilled in ocean is a global challenge, especially in Bohai, due to its slow current movement and poor self-purification capacity. Frequent oil-spill accidents not only cause severe and long-term damages to marine ecosystems, but also lead to a great loss of valuable resources. To eliminate the environmental pollution of oil spills, an efficient and environment-friendly oil-recovery approach is necessary. In this study, 1 expanded graphite (EG) modified by CTAB-KBr/H 3 PO 4 was synthesized via composite intercalation agents of CTAB-KBr and natural flake graphite, followed by the activation of phosphoric acid at low temperature. The resultant modified expanded graphite (M-EG) obtained an interconnected and continuous open microstructure with lower polarity surface, more and larger pores, and increased surface hydrophobicity. Due to these characteristics, M-EG exhibited a superior adsorption capacity towards marine oil. The saturated adsorption capacities of M-EG were as large as 7.44  g/g for engine oil, 6.12 g/g for crude oil, 5.34 g/g for diesel oil and 4.10 g/g for gasoline oil in 120min, exceeding the capacity of pristine EG. Furthermore, M-EG maintained good removal efficiency under different adsorption conditions, such as temperature, oil types, and sodium salt concentration. In addition, oils sorbed into M-EG could be recovered either by a simple compression or filtration-drying treatment with a recovery ratio of 58-83%. However, filtration-drying treatment shows better performance in preserving microstructures of M-EG, which ensures the adsorbents can be recycled several times. High removal capability, fast adsorption efficiency, excellent stability and good recycling performance make M-EG an ideal candidate for treating marine oil pollution in practical application. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modelling of ceramide interactions with porous graphite carbon in non-aqueous liquid chromatography.

PubMed

West, C; Cilpa, G; Gaudin, K; Chaminade, P; Lesellier, E

2005-09-16

Interactions of solutes on porous graphitic carbon (PGC) with non-aqueous mobile phases are studied by the linear solvation energy relationship (LSER). Studies have been carried out with eight binary mixtures composed of a weak solvent (acetonitrile or methanol) and a strong solvent (tetrahydrofuran, n-butanol, CH2Cl2, 1,1,2-trichloro-2,2,1-trifluoroethane). The systematic analysis of a set of test compounds was performed for each solvent mixture in isocratic mode (50:50). The results were compared to those obtained on PGC with hydro-organic liquids and supercritical fluids. They were then correlated with the observed retention behaviour of lipid compounds, more particularly ceramides.

Feasibility of high-resolution continuum source molecular absorption spectrometry in flame and furnace for sulphur determination in petroleum products

NASA Astrophysics Data System (ADS)

Kowalewska, Zofia

2011-07-01

For the first time, high-resolution molecular absorption spectrometry with a high-intensity xenon lamp as radiation source has been applied for the determination of sulphur in crude oil and petroleum products. The samples were analysed as xylene solutions using vaporisation in acetylene-air flame or in an electrothermally heated graphite furnace. The sensitive rotational lines of the CS molecule, belonging to the ∆ν = 0 vibrational sequence within the electronic transition X 1∑ + → A 1П, were applied. For graphite furnace molecular absorption spectrometry, the Pd + Mg organic modifier was selected. Strong interactions with Pd atoms enable easier decomposition of sulphur-containing compounds, likely through the temporal formation of Pd xS y molecules. At the 258.056 nm line, with the wavelength range covering central pixel ± 5 pixels and with application of interactive background correction, the detection limit was 14 ng in graphite furnace molecular absorption spectrometry and 18 mg kg -1 in flame molecular absorption spectrometry. Meanwhile, application of 2-points background correction found a characteristic mass of 12 ng in graphite furnace molecular absorption spectrometry and a characteristic concentration of 104 mg kg -1 in flame molecular absorption spectrometry. The range of application of the proposed methods turned out to be significantly limited by the properties of the sulphur compounds of interest. In the case of volatile sulphur compounds, which can be present in light petroleum products, severe difficulties were encountered. On the contrary, heavy oils and residues from distillation as well as crude oil could be analysed using both flame and graphite furnace vaporisation. The good accuracy of the proposed methods for these samples was confirmed by their mutual consistency and the results from analysis of reference samples (certified reference materials and home reference materials with sulphur content determined by X-ray fluorescence spectrometry).

Layered gadolinium hydroxides for simultaneous drug delivery and imaging.

PubMed

Xu, Yadong; Goyanes, Alvaro; Wang, Yuwei; Weston, Andrew J; So, Po-Wah; Geraldes, Carlos F G C; Fogg, Andrew M; Basit, Abdul W; Williams, Gareth R

2018-02-27

The potential of the layered gadolinium hydroxide (LGdH) [Gd 2 (OH) 5 ]Cl·yH 2 O (LGdH-Cl) for simultaneous drug delivery and magnetic resonance imaging was explored in this work. Three non-steroidal anti-inflammatory drugs (diclofenac [dic], ibuprofen [ibu], and naproxen [nap]) were intercalated into LGdH-Cl for the first time, using three different routes (ion exchange intercalation, coprecipitation, and exfoliation-self-assembly). X-ray diffraction, elemental microanalysis and IR spectroscopy confirmed successful incorporation of the drug into the interlayer spaces of the LGdH in all cases. From a comparison of the guest anion sizes and interlayer spacings, the active ingredients are believed to adopt intertwined bilayer configurations between the LGdH layers. The materials prepared by coprecipitation in general have noticeably higher drug loadings than those produced by ion exchange or self-assembly, as a result of the incorporation of some neutral drug into the composites. The LGdH-drug intercalates are stable at neutral pH, but rapidly degrade in acidic conditions to free Gd 3+ into solution. While LGdH-nap releases its drug loading into solution very rapidly (within ca. 1.5 h) at pH 7.4, LGdH-dic shows sustained release over 4 h, and LGdH-ibu extends this to 24 h. The latter composites therefore can be incorporated into enteric-coated tablets to provide sustained release in the small intestine. The drug intercalates are highly biocompatible and retain the proton relaxivity properties of the parent LGdH-Cl, with the materials most promising for use as negative contrast agents in MRI. Overall, the LGdH-drug intercalation compounds appear to have great potential for use in theranostic applications.

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

Zhang Hui; Zou Kang; Guo Shaohuan

A nanostructural drug-inorganic clay composite involving a pharmaceutically active compound captopril (Cpl) intercalated Mg-Al-layered double hydroxides (Cpl-LDHs) with Mg/Al molar ratio of 2.06 has been assembled by coprecipitation method. Powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR) and Raman spectra analysis indicate a successful intercalation of Cpl between the layers with a vertical orientation of Cpl disulphide-containing S-S linkage. SEM photo indicates that as-synthesized Cpl-LDHs possess compact and non-porous structure with approximately and linked elliptical shape particles of ca. 50 nm. TG-DTA analyses suggest that the thermal stability of intercalated organic species is largely enhanced due to host-guest interactionmore » involving the hydrogen bond compared to pure form before intercalation. The in vitro release studies show that both the release rate and release percentages markedly decrease with increasing pH from 4.60 to 7.45 due to possible change of release mechanism during the release process. The kinetic simulation for the release data, and XRD and FT-IR analyses for samples recovered from release media indicate that the dissolution mechanism is mainly responsible for the release behaviour of Cpl-LDHs at pH 4.60, while the ion-exchange one is responsible for that at pH 7.45. - Graphical abstract: Based on XRD, FT-IR and Raman spectra analyses, it is suggested that captopril (Cpl) exists as its disulphide metabolites in the interlayer of Mg-Al-LDHs via hydrogen bonding between guest carboxylate function and hydroxyl group of the host layers. A schematic supramolecular structure of Cpl intercalates involving a vertical orientation of Cpl disulphide-containing S-S bond between the layers with carboxylate anions pointing to both hydroxide layers is presented.« less

Intermolecular interactions between imidazole derivatives intercalated in layered solids. Substituent group effect

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

González, M.; Lemus-Santana, A.A.; Rodríguez-Hernández, J.

2013-08-15

This study sheds light on the intermolecular interactions between imidazole derive molecules (2-methyl-imidazole, 2-ethyl-imidazole and benzimidazole) intercalated in T[Ni(CN){sub 4}] layers to form a solid of formula unit T(ImD){sub 2}[Ni(CN){sub 4}]. These hybrid inorganic–organic solids were prepared by soft chemical routes and their crystal structures solved and refined from X-ray powder diffraction data. The involved imidazole derivative molecules were found coordinated through the pyridinic N atom to the axial positions for the metal T in the T[Ni(CN){sub 4}] layer. In the interlayers region ligand molecules from neighboring layers remain stacked in a face-to-face configuration through dipole–dipole and quadrupole–quadrupole interactions. Thesemore » intermolecular interactions show a pronounced dependence on the substituent group and are responsible for an ImD-pillaring concatenation of adjacent layers. This is supported by the structural information and the recorded magnetic data in the 2–300 K temperature range. The samples containing Co and Ni are characterized by presence of spin–orbit coupling and pronounced temperature dependence for the effective magnetic moment except for 2-ethyl-imidazole related to the local distortion for the metal coordination environment. For this last one ligand a weak ferromagnetic ordering ascribed to a super-exchange interaction between T metals from neighboring layers through the ligands π–π interaction was detected. - Graphical abstract: In the interlayers region imidazole derivative molecules are oriented according to their dipolar and quadrupolar interactions and minimizing the steric impediment. Highlights: • Imidazole derivatives intercalation compounds. • Intermolecular interaction between intercalated imidazole derivatives. • Hybrid inorganic–organic solids. • Pi–pi interactions and ferromagnetic coupling. • Dipolar and quadrupolar interactions between intercalated imidazole derivatives.« less

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

Electrostatic spray deposition of porous Fe 2O 3 thin films as anode material with improved electrochemical performance for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, L.; Xu, H. W.; Chen, P. C.; Zhang, D. W.; Ding, C. X.; Chen, C. H.

Iron oxide materials are attractive anode materials for lithium-ion batteries for their high capacity and low cost compared with graphite and most of other transition metal oxides. Porous carbon-free α-Fe 2O 3 films with two types of pore size distribution were prepared by electrostatic spray deposition, and they were characterized by X-ray diffraction, scanning electron microscopy and X-ray absorption near-edge spectroscopy. The 200 °C-deposited thin film exhibits a high reversible capacity of up to 1080 mAh g -1, while the initial capacity loss is at a remarkable low level (19.8%). Besides, the energy efficiency and energy specific average potential (E av) of the Fe 2O 3 films during charge/discharge process were also investigated. The results indicate that the porous α-Fe 2O 3 films have significantly higher energy density than Li 4Ti 5O 12 while it has a similar E av of about 1.5 V. Due to the porous structure that can buffer the volume changes during lithium intercalation/de-intercalation, the films exhibit stable cycling performance. As a potential anode material for high performance lithium-ion batteries that can be applied on electric vehicle and energy storage, rate capability and electrochemical performance under high-low temperatures were also investigated.

Capillary suspensions as beneficial formulation concept for high energy density Li-ion battery electrodes

NASA Astrophysics Data System (ADS)

Bitsch, Boris; Gallasch, Tobias; Schroeder, Melanie; Börner, Markus; Winter, Martin; Willenbacher, Norbert

2016-10-01

We introduce a novel formulation concept to prepare high capacity graphite electrodes for lithium ion batteries. The concept is based on the capillary suspension phenomenon: graphite and conductive agent are dispersed in an aqueous binder solution and the organic solvent octanol is added as immiscible, secondary fluid providing the formation of a sample-spanning network resulting in unique stability and coating properties. No additional processing steps compared to conventional slurry preparation are required. The resulting ultra-thick electrodes comprise mass loadings of about 16.5 mg cm-2, uniform layer thickness, and superior edge contours. The adjustment of mechanical energy input ensures uniform distribution of the conductive agent and sufficient electronic conductivity of the final dry composite electrode. The resulting pore structure is due to the stable network provided by the secondary fluid which evaporates residue-free during drying. Constant current-constant potential (CC-CP) cycling clearly indicates that the corresponding microstructure significantly improves the kinetics of reversible Li+ (de-) intercalation. A double layer electrode combining a conventionally prepared layer coated directly onto the Cu current collector with an upper layer stabilized with octanol was prepared applying wet-on-wet coating. CC-CP cycling data confirms that staged porosity within the electrode cross section results in superior electrochemical performance.

Selective inhibition of Bacillus subtilis sporulation by acridine orange and promethazine.

PubMed

Burke, W F; Spizizen, J

1977-03-01

Two structurally similar compounds were found to inhibit sporulation in Bacillus subtilis 168. A dye, acridine orange, and an antischizophrenic drug, promethazine, blocked spore formation at concentrations subinhibitory to vegetative growth, while allowing synthesis of serine protease, antibiotic, and certain catabolite-repressed enzymes. The sporulation process was sensitive to promethazine through T2, whereas acridine orange was inhibitory until T4. The drug-treated cells were able to support the replication of phages phie and phi29, although the lytic cycles were altered slightly. The selective inhibition of sporulation by these compounds may be related to the affinity of some sporulation-specific genes to intercalating compounds.

Development of differential cytotoxic compounds containing nitrosourea and benzothiazine nucleus.

PubMed

Nyati, M K; Rai, D; Gupta, R R; Dev, P K

1997-01-01

The in vivo activity of 4 new benzothiazinyl-nitrosourea compounds was investigated against Sarcoma-180 (S-180) and Ehrlich Ascitic Carcinoma (EAC) induced ascitic and solid tumors. EAC solid tumor was found to be the most sensitive, where one compound (no 4) inhibited tumor growth to only 3 per cent of the control value. All the 4 compounds tested were found to be toxicologically more selective than 5-fluorouracil and 6-mercaptopurine drugs. The reason for this selective toxicity may be attributed to the inhibition of isocyanate moiety in these compounds which causes toxicity to normal cells via a carbamoylation reaction. However, they may still remain potent, since they decompose into an alkylating carbonium species and a charge transfer complex which may interact with DNA via alkylation and intercalation reactions, respectively.

Observation of self-regulating response in Li xM yMn 2-yO 4 (M=Mn, Ni): A study using density functional theory

NASA Astrophysics Data System (ADS)

Ragavendran, K.; Sherwood, Daniel; Emmanuel, Bosco

2009-02-01

Density functional theory is used to understand the response of the transition metal-oxygen octahedra in Li xMn 2O 4 and Li xNi 0.5Mn 1.5O 4 to lithium intercalation and de-intercalation. Electronic structure computations on these compounds for x=0, 0.5 and 1 indicate that the 3d DOS of Mn is almost unaffected to variations in x. On the other hand, the oxygen 2p-DOS and to a lesser extent Ni 3d DOS are found to be sensitive to perturbation. The observations are explained on the grounds of self-regulating response, characteristic of systems having localized d states that communicate with a covalent manifold.

ZnO Functionalization of Surface Pre-treated Multi-walled Carbon Nanotubes for Methane Sensing

EPA Science Inventory

Bare carbon nanotubes (CNTs) cannot be used to sense most gases due to poor bonding between the chemically inert graphitic surface and the different compounds CNTs are exposed to. Consequently, for gas sensing applications, functionalization of CNTs with reactive compounds is req...

Synthetic Fabrication of Nanoscale MoS2-Based Transition Metal Sulfides

PubMed Central

Wang, Shutao; An, Changhua; Yuan, Jikang

2010-01-01

Transition metal sulfides are scientifically and technologically important materials. This review summarizes recent progress on the synthetic fabrication of transition metal sulfides nanocrystals with controlled shape, size, and surface functionality. Special attention is paid to the case of MoS2 nanoparticles, where organic (surfactant, polymer), inorganic (support, promoter, doping) compounds and intercalation chemistry are applied.

State-of-the-Art Technologies for Construction in Space: a Review.

DTIC Science & Technology

1987-09-01

reinforcing fiber or fiber mat. Investigations of bonding, thermal stress, forming tech- niques, specific strengths, specific moduli, and microfracture...diameter and about 15 ft long. The graphite fibers follow the length of the tube and the polymer compound used as the matrix is applied over the graphite...combination of Sthese approaches to obtain the best simulation of the low-Earth orbit environment. Most materials tested to date are polymers such as

Styrene-terminated polysulfone oligomers as matrix material for graphite reinforced composites: An initial study

NASA Technical Reports Server (NTRS)

Garcia, Dana; Bowles, Kenneth J.; Vannucci, Raymond D.

1987-01-01

Styrene terminated polysulfone oligomers are part of an oligomeric class of compounds with end groups capable of thermal polymerization. These materials can be used as matrices for graphite reinforced composites. The initial evaluation of styrene terminated polysulfone oligomer based composites are summarized in terms of fabrication methods, and mechanical and environmental properties. In addition, a description and evaluation is provided of the NASA/Industry Fellowship Program for Technology Transfer.

Extending the applicability of the Tkatchenko-Scheffler dispersion correction via iterative Hirshfeld partitioning

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

Bučko, Tomáš, E-mail: bucko@fns.uniba.sk; Department of Computational Materials Physics, Fakultät für Physik and Center for Computational Materials Science, Universität Wien, Sensengasse, Wien 1090; Lebègue, Sébastien, E-mail: sebastien.lebegue@univ-lorraine.fr

2014-07-21

Recently we have demonstrated that the applicability of the Tkatchenko-Scheffler (TS) method for calculating dispersion corrections to density-functional theory can be extended to ionic systems if the Hirshfeld method for estimating effective volumes and charges of atoms in molecules or solids (AIM’s) is replaced by its iterative variant [T. Bučko, S. Lebègue, J. Hafner, and J. Ángyán, J. Chem. Theory Comput. 9, 4293 (2013)]. The standard Hirshfeld method uses neutral atoms as a reference, whereas in the iterative Hirshfeld (HI) scheme the fractionally charged atomic reference states are determined self-consistently. We show that the HI method predicts more realistic AIMmore » charges and that the TS/HI approach leads to polarizabilities and C{sub 6} dispersion coefficients in ionic or partially ionic systems which are, as expected, larger for anions than for cations (in contrast to the conventional TS method). For crystalline materials, the new algorithm predicts polarizabilities per unit cell in better agreement with the values derived from the Clausius-Mosotti equation. The applicability of the TS/HI method has been tested for a wide variety of molecular and solid-state systems. It is demonstrated that for systems dominated by covalent interactions and/or dispersion forces the TS/HI method leads to the same results as the conventional TS approach. The difference between the TS/HI and TS approaches increases with increasing ionicity. A detailed comparison is presented for isoelectronic series of octet compounds, layered crystals, complex intermetallic compounds, and hydrides, and for crystals built of molecules or containing molecular anions. It is demonstrated that only the TS/HI method leads to accurate results for systems where both electrostatic and dispersion interactions are important, as illustrated for Li-intercalated graphite and for molecular adsorption on the surfaces in ionic solids and in the cavities of zeolites.« less

First-principles estimates of free energy barriers for Mg desolvation and intercalation at electrolyte/electrode interfaces

NASA Astrophysics Data System (ADS)

Wan, Liwen; Prendergast, David

2014-03-01

There is a growing interest in developing multivalent ion batteries that could, in principle, double or triple the energy density compared to the monovalent Li-ion batteries. However, the strong electrostatic interaction caused by the extra charge also makes it very challenging to find appropriate intercalation compounds that allow for relatively fast and reversible ion transport. An established working multivalent battery is comprised of Mg(AlCl2BuEt)2 salts in THF solution as the electrolyte, and Mg metal and Mo6S8 Chevrel phase as the anode and cathode, respectively. Currently, we lack a clear understanding of the mechanism for Mg desolvation and intercalation at the interface between the electrolyte and Chevrel phase surfaces, which is critical in designing new advanced battery systems with improved ion diffusion rate. Here, we present a theoretical investigation of the dynamics and kinetics of the Mg desolvation/intercalation process. The surface properties of Mo6S8 are studied for the first time using density functional theory (DFT) and its interaction with the electrolyte is simulated via an ab initio molecular dynamics (AIMD) approach. The free energy barrier for Mg diffusing through the interface is then calculated by performing a set of biased AIMD simulations. This work is supported as part of the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.

A novel coronene//Na2Ti3O7 dual-ion battery

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

Dong, Shengyang; Li, Zhifei; Rodríguez-Pérez, Isma

Here we construct a novel sodium dual-ion battery (Na-DIB) with a conventional alkyl/alkylene carbonate electrolyte by using reduced-graphene-oxide-coated Na2Ti3O7 (NTO@G) as the anode and coronene, a polycyclic aromatic hydrocarbon (PAH), as the cathode. The coronene//NTO@G configuration delivers a specific energy of 77 W h kg−1, based on the total active mass in both electrodes, and excellent cycling stability with 80% capacity retention after 5000 cycles. In addition, this device can work well in a wide range of temperatures from −20 to 40 °C. The results demonstrate a proof-of-concept Na-DIB that avoids the challenges of conventional dual-graphite DIBs by utilizing non-graphitemore » intercalation anode and cathode, and a carbonate-based electrolyte without any additives.« less

High voltage electrochemical double layer capacitors using conductive carbons as additives

NASA Astrophysics Data System (ADS)

Michael, M. S.; Prabaharan, S. R. S.

We describe here an interesting approach towards electrochemical capacitors (ECCs) using graphite materials (as being used as conductive additives in rechargeable lithium-ion battery cathodes) in a Li + containing organic electrolyte. The important result is that we achieved a voltage window of >4 V, which is rather large, compared to the standard window of 2.5 V for ordinary electric double layer capacitors (DLCs). The capacitor performance was evaluated by cyclic voltammetry (CV) and galvanostatic charge/discharge techniques. From charge-discharge studies of the symmetrical device (for instance, SFG6 carbon electrode), a specific capacitance of up to 14.5 F/g was obtained at 16 mA/cm 2 current rate and at a low current rate (3 mA/cm 2), a higher value was obtained (63 F/g). The specific capacitance decreased about 25% after 1000 cycles compared to the initial discharge process. The performances of these graphites are discussed in the light of both double layer capacitance (DLC) and pseudocapacitance (battery-like behavior). The high capacitance obtained was not only derived from the current-transient capacitive behavior but is also attributed to pseudocapacitance associated with some kind of faradaic reaction, which could probably occur due to Li + intercalation/deintercalation reactions into graphitic layers of the carbons used. The ac impedance (electrochemical impedances spectroscopy, EIS) measurements were also carried out to evaluate the capacitor parameters such as equivalent series resistance (ESR) and frequency dependent capacitance ( Cfreq). Cyclic voltammetry measurements were also performed to evaluate the cycling behavior of the carbon electrodes and the non-rectangular shaped voltammograms revealed the non-zero time constant [ τ( RC)≠0] confirming that the current contains a transient as well as steady-state components.

Process for producing metal compounds from graphite oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

Process for Producing Metal Compounds from Graphite Oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon. metal. chloride. and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon. metal carbonate. and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide: b) in an inert environment to produce metal oxide on carbon substrate: c) in a reducing environment. to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

Kinetic phase evolution of spinel cobalt oxide during lithiation

DOE PAGES

Li, Jing; He, Kai; Meng, Qingping; ...

2016-09-15

Spinel cobalt oxide has been proposed to undergo a multiple-step reaction during the electrochemical lithiation process. Understanding the kinetics of the lithiation process in this compound is crucial to optimize its performance and cyclability. In this work, we have utilized a low-angle annular dark-field scanning transmission electron microscopy method to visualize the dynamic reaction process in real time and study the reaction kinetics at different rates. We show that the particles undergo a two-step reaction at the single-particle level, which includes an initial intercalation reaction followed by a conversion reaction. At low rates, the conversion reaction starts after the intercalationmore » reaction has fully finished, consistent with the prediction of density functional theoretical calculations. At high rates, the intercalation reaction is overwhelmed by the subsequently nucleated conversion reaction, and the reaction speeds of both the intercalation and conversion reactions are increased. Phase-field simulations show the crucial role of surface diffusion rates of lithium ions in controlling this process. Furthermore, this work provides microscopic insights into the reaction dynamics in non-equilibrium conditions and highlights the effect of lithium diffusion rates on the overall reaction homogeneity as well as the performance.« less

Kinetic phase evolution of spinel cobalt oxide during lithiation

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

Li, Jing; He, Kai; Meng, Qingping

Spinel cobalt oxide has been proposed to undergo a multiple-step reaction during the electrochemical lithiation process. Understanding the kinetics of the lithiation process in this compound is crucial to optimize its performance and cyclability. In this work, we have utilized a low-angle annular dark-field scanning transmission electron microscopy method to visualize the dynamic reaction process in real time and study the reaction kinetics at different rates. We show that the particles undergo a two-step reaction at the single-particle level, which includes an initial intercalation reaction followed by a conversion reaction. At low rates, the conversion reaction starts after the intercalationmore » reaction has fully finished, consistent with the prediction of density functional theoretical calculations. At high rates, the intercalation reaction is overwhelmed by the subsequently nucleated conversion reaction, and the reaction speeds of both the intercalation and conversion reactions are increased. Phase-field simulations show the crucial role of surface diffusion rates of lithium ions in controlling this process. Furthermore, this work provides microscopic insights into the reaction dynamics in non-equilibrium conditions and highlights the effect of lithium diffusion rates on the overall reaction homogeneity as well as the performance.« less

The Effect of Single, Binary and Ternary Anions of Chloride, Carbonate and Phosphate on the Release of 2,4-Dichlorophenoxyacetate Intercalated into the Zn-Al-layered Double Hydroxide Nanohybrid

NASA Astrophysics Data System (ADS)

Hussein, Mohd Zobir; Jaafar, Adila Mohamad; Yahaya, Asmah Hj.; Zainal, Zulkarnain

2009-11-01

Intercalation of beneficial anion into inorganic host has lead to an opportunity to synthesize various combinations of new organic-inorganic nanohybrids with various potential applications; especially, for the controlled release formulation and storage purposes. Investigation on the release behavior of 2,4-dichlorophenoxyacetate (2,4-D) intercalated into the interlayer of Zn-Al-layered double hydroxide (ZAN) have been carried out using single, binary and ternary aqueous systems of chloride, carbonate and phosphate. The release behavior of the active agent 2,4-D from its double-layered hydroxide nanohybrid ZANDI was found to be of controlled manner governed by pseudo-second order kinetics. It was found that carbonate medium yielded the highest accumulated release of 2,4-D, while phosphate in combination with carbonate and/or nitrate speeds up the release rate of 2,4-D. These results indicate that it is possible to design and develop new delivery system of latex stimulant compound with controlled release property based on 2,4-D that is known as a substance to increase latex production of rubber tree, Hevea brasiliensis.

NLP-1: a DNA intercalating hypoxic cell radiosensitizer and cytotoxin

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

Panicucci, R.; Heal, R.; Laderoute, K.

The 2-nitroimidazole linked phenanthridine, NLP-1 (5-(3-(2-nitro-1-imidazoyl)-propyl)-phenanthridinium bromide), was synthesized with the rationale of targeting the nitroimidazole to DNA via the phenanthridine ring. The drug is soluble in aqueous solution (greater than 25 mM) and stable at room temperature. It binds to DNA with a binding constant 1/30 that of ethidium bromide. At a concentration of 0.5 mM, NLP-1 is 8 times more toxic to hypoxic than aerobic cells at 37 degrees C. This concentration is 40 times less than the concentration of misonidazole, a non-intercalating 2-nitroimidazole, required for the same degree of hypoxic cell toxicity. The toxicity of NLP-1 ismore » reduced at least 10-fold at 0 degrees C. Its ability to radiosensitize hypoxic cells is similar to misonidazole at 0 degrees C. Thus the putative targeting of the 2-nitroimidazole, NLP-1, to DNA, via its phenanthridine group, enhances its hypoxic toxicity, but not its radiosensitizing ability under the present test conditions. NLP-1 represents a lead compound for intercalating 2-nitroimidazoles with selective toxicity for hypoxic cells.« less

Electrochemical Ultracapacitors Using Graphitic Nanostacks

NASA Technical Reports Server (NTRS)

Marotta, Christopher

2012-01-01

Electrochemical ultracapacitors (ECs) have been developed using graphitic nanostacks as the electrode material. The advantages of this technology will be the reduction of device size due to superior power densities and relative powers compared to traditional activated carbon electrodes. External testing showed that these materials display reduced discharge response times compared to state-of-the-art materials. Such applications are advantageous for pulsed power applications such as burst communications (satellites, cell phones), electromechanical actuators, and battery load leveling in electric vehicles. These carbon nanostructures are highly conductive and offer an ordered mesopore network. These attributes will provide more complete electrolyte wetting, and faster release of stored charge compared to activated carbon. Electrochemical capacitor (EC) electrode materials were developed using commercially available nanomaterials and modifying them to exploit their energy storage properties. These materials would be an improvement over current ECs that employ activated carbon as the electrode material. Commercially available graphite nanofibers (GNFs) are used as precursor materials for the synthesis of graphitic nanostacks (GNSs). These materials offer much greater surface area than graphite flakes. Additionally, these materials offer a superior electrical conductivity and a greater average pore size compared to activated carbon electrodes. The state of the art in EC development uses activated carbon (AC) as the electrode material. AC has a high surface area, but its small average pore size inhibits electrolyte ingress/egress. Additionally, AC has a higher resistivity, which generates parasitic heating in high-power applications. This work focuses on fabricating EC from carbon that has a very different structure by increasing the surface area of the GNF by intercalation or exfoliation of the graphitic basal planes. Additionally, various functionalities to the GNS surface will be added that can exhibit pseudocapacitance. This pseudocapacitance exhibits faradaic (charge transfer) properties that can further increase the overall relative and volumetric capacitance of the material. A process is also proposed to use GNF as a precursor material to fabricate GNS that will be used as EC electrodes. This results in much better electrical conductivity than activated carbon. This is advantageous for high-pulsed-power applications to reduce parasitic heating. Larger average pore size allows more complete electrolyte wetting (faster charge transfer kinetics). These properties contribute to a lowered equivalent series resistance (ESR), increased specific power, shorter charging times, and decreased parasitic heating. The high density of basal plane edges provides nucleation sites for activation (addition of hydrophilic functional groups) that facilitate electrolyte wetting, and will contribute to pseudocapacitance.

Coatings for graphite fibers

NASA Technical Reports Server (NTRS)

Galasso, F. S.; Scola, D. A.; Veltri, R. D.

1980-01-01

Graphite fibers released from composites during burning or an explosion caused shorting of electrical and electronic equipment. Silicon carbide, silica, silicon nitride and boron nitride were coated on graphite fibers to increase their electrical resistances. Resistances as high as three orders of magnitude higher than uncoated fiber were attained without any significant degradation of the substrate fiber. An organo-silicone approach to produce coated fibers with high electrical resistance was also used. Celion 6000 graphite fibers were coated with an organo-silicone compound, followed by hydrolysis and pyrolysis of the coating to a silica-like material. The shear and flexural strengths of composites made from high electrically resistant fibers were considerably lower than the shear and flexural strengths of composites made from the lower electrically resistant fibers. The lower shear strengths of the composites indicated that the coatings on these fibers were weaker than the coating on the fibers which were pyrolyzed at higher temperature.

Design, synthesis, molecular modeling and anti-proliferative evaluation of novel quinoxaline derivatives as potential DNA intercalators and topoisomerase II inhibitors.

PubMed

Ibrahim, M K; Taghour, M S; Metwaly, A M; Belal, A; Mehany, A B M; Elhendawy, M A; Radwan, M M; Yassin, A M; El-Deeb, N M; Hafez, E E; ElSohly, M A; Eissa, I H

2018-06-04

New series of [1,2,4]triazolo [4,3-a]quinoxaline and bis([1,2,4]triazolo)[4,3-a:3',4'-c]quinoxaline derivatives have been designed, synthesized and biologically evaluated for their cytotoxic activities against three tumor cell lines (HePG-2, Hep-2 and Caco-2). Compounds 16 e , 21, 25 a and 25 b exhibited the highest activities against the examined cell lines with IC 50 values ranging from 0.29 to 0.90 μM comparable to that of doxorubicin (IC 50 ranging from 0.51 to 0.73 μM). The most active members were further evaluated for their topoisomerase II (Topo II) inhibitory activities and DNA intercalating affinities as potential mechanisms for their anti-proliferative activities. Interestingly, the results of Topo II inhibition and DNA binding assays were consistent with that of the cytotoxicity data, where the most potent anti-proliferative derivatives exhibited good Topo II inhibitory activities and DNA binding affinities, comparable to that of doxorubicin. Moreover, the most active compound 25 a caused cell cycle arrest at G2/M phase and induced apoptosis in Caco-2 cells. In addition, Furthermore, molecular docking studies were performed for the novel compounds against DNA-Topo II complex to investigate their binding patterns. Based on these studies, it was concluded that DNA binding and/or Topo II inhibition may contribute to the observed cytotoxicity of the synthesized compounds. Copyright © 2018. Published by Elsevier Masson SAS.

Investigation of the complex structure, comparative DNA-binding and DNA cleavage of two water-soluble mono-nuclear lanthanum(III) complexes and cytotoxic activity of chitosan-coated magnetic nanoparticles as drug delivery for the complexes

NASA Astrophysics Data System (ADS)

Asadi, Zahra; Nasrollahi, Neda; Karbalaei-Heidari, Hamidreza; Eigner, Vaclav; Dusek, Michal; Mobaraki, Nabiallah; Pournejati, Roya

2017-05-01

Two water-soluble mono-nuclear macrocyclic lanthanum(III) complexes of 2,6-diformyl-4-methylphenol with 1,3-diamino-2-propanol (C1) or 1,3-propylenediamine (C2) were synthesized and characterized by UV-Vis, FT-IR, 13C and 1H NMR spectroscopy and elemental analysis. C1 complex was structurally characterized by single-crystal X-ray diffraction, which revealed that the complex was mononuclear and ten-coordinated. The coordination sites around lanthanum(III) were occupied with a five-dentate ligand, two bidentate nitrates, and one water molecule. The interaction of complexes with DNA was studied in buffered aqueous solution at pH 7.4. UV-Vis absorption spectroscopy, emission spectroscopy, circular dichroism (CD) and viscometric measurements provided clear evidence of the intercalation mechanism of binding. The obtained intrinsic binding constants (Kb) 9.3 × 103 and 1.2 × 103 M- 1 for C1 and C2, respectively confirmed that C1 is better intercalator than C2. The DNA docking studies suggested that the complexes bind with DNA in a groove binding mode with the binding affinity of C1 > C2. Moreover, agarose gel electrophoresis study of the DNA-complex for both compounds revealed that the C1 intercalation cause ethidium bromide replacement in a competitive manner which confirms the suggested mechanism of binding. Finally, the anticancer experiments for the treated cancerous cell lines with both synthesized compounds show that these hydrophilic molecules need a suitable carrier to pass through the hydrophobic nature of cell membrane efficiently.

Engineering the Transformation Strain in LiMn y Fe 1–y PO 4 Olivines for Ultrahigh Rate Battery Cathodes

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

Ravnsbæk, Dorthe B.; Xiang, Kai; Xing, Wenting

2016-04-13

Alkali ion intercalation compounds used as battery electrodes often exhibit first-order phase transitions during electro-chemical cycling, accompanied by significant transformation strains. Despite 30 years of research into the behavior of such compounds, the relationship between transformation strain and electrode performance, especially the rate at which working ions (e.g., Li) can be intercalated and deintercalated, is still absent. In this work, we use the LiMn yFe 1-yPO 4 system for a systematic study, and measure using operando synchrotron radiation powder X-ray diffraction (SR-PXD) the dynamic strain behavior as a function of the Mn content (y) in powders of similar to 50more » nm average diameter. The dynamically produced strain deviates significantly from what is expected from the equilibrium phase diagrams and demonstrates metastability but nonetheless spans a wide range from 0 to 8 vol % with y. For the first time, we show that the discharge capacity at high C-rates (20-50C rate) varies in inverse proportion to the transformation strain, implying that engineering electrode materials for reduced strain can be used to maximize the power capability of batteries.« less

Processable high temperature resistant addition type polyimide laminating resins

NASA Technical Reports Server (NTRS)

Serafini, T. T.; Delvigs, P.

1973-01-01

Basic studies that were performed using model compounds to elucidate the polymerization mechanism of the so-called addition-type (A-type) polyimides are reviewed. The fabrication and properties of polyimide/graphite fiber composites using A-type polyimide prepolymers as the matrix are also reviewed. An alternate method for preparing processable A-type polyimides by means of in situ polymerization of monomer reactants (PMR) on the fiber reinforcement is described. The elevated temperature properties of A-type PMR/graphite fiber composites are also presented.

Stress analysis and failure of an internally pressurized composite-jacketed steel cylinder

NASA Technical Reports Server (NTRS)

Chen, Peter C. T.

1992-01-01

This paper presents a nonlinear stress analysis of a thick-walled compound tube subjected to internal pressure. The compound tube is constructed of a steel liner and a graphite-bismaleimide outer shell. Analytical expressions for the stresses, strains, and displacements are derived for all loading ranges up to failure. Numerical results for the stresses and the maximum value that the compound tube can contain without failure are presented.

Non-crosslinked, amorphous, block copolymer electrolyte for batteries

DOEpatents

Mayes, Anne M.; Ceder, Gerbrand; Chiang, Yet-Ming; Sadoway, Donald R.; Aydinol, Mehmet K.; Soo, Philip P.; Jang, Young-Il; Huang, Biying

2006-04-11

Solid battery components are provided. A block copolymeric electrolyte is non-crosslinked and non-glassy through the entire range of typical battery service temperatures, that is, through the entire range of at least from about 0.degree. C. to about 70.degree. C. The chains of which the copolymer is made each include at least one ionically-conductive block and at least one second block immiscible with the ionically-conductive block. The chains form an amorphous association and are arranged in an ordered nanostructure including a continuous matrix of amorphous ionically-conductive domains and amorphous second domains that are immiscible with the ionically-conductive domains. A compound is provided that has a formula of Li.sub.xM.sub.yN.sub.zO.sub.2. M and N are each metal atoms or a main group elements, and x, y and z are each numbers from about 0 to about 1. y and z are chosen such that a formal charge on the M.sub.yN.sub.z portion of the compound is (4-x). In certain embodiments, these compounds are used in the cathodes of rechargeable batteries. The present invention also includes methods of predicting the potential utility of metal dichalgogenide compounds for use in lithium intercalation compounds. It also provides methods for processing lithium intercalation oxides with the structure and compositional homogeneity necessary to realize the increased formation energies of said compounds. An article is made of a dimensionally-stable, interpenetrating microstructure of a first phase including a first component and a second phase, immiscible with the first phase, including a second component. The first and second phases define interphase boundaries between them, and at least one particle is positioned between a first phase and a second phase at an interphase boundary. When the first and second phases are electronically-conductive and ionically-conductive polymers, respectively, and the particles are ion host particles, the arrangement is an electrode of a battery.

Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism.

PubMed

Vollmeyer, Joscha; Eberhagen, Friederike; Höger, Sigurd; Jester, Stefan-S

2014-01-01

Three shape-persistent naphthylene-phenylene-acetylene macrocycles of identical backbone structures and extraannular substitution patterns but different (empty, apolar, polar) nanopore fillings are self-assembled at the solid/liquid interface of highly oriented pyrolytic graphite and 1,2,4-trichlorobenzene. Submolecularly resolved images of the resulting two-dimensional (2D) crystalline monolayer patterns are obtained by in situ scanning tunneling microscopy. A concentration-dependent conformational polymorphism is found, and open and more dense packing motifs are observed. For all three compounds alike lattice parameters are found, therefore the intermolecular macrocycle distances are mainly determined by their size and symmetry. This is an excellent example that the graphite acts as a template for the macrocycle organization independent from their specific interior.

Nanoarchitectured Nb2O5 hollow, Nb2O5@carbon and NbO2@carbon Core-Shell Microspheres for Ultrahigh-Rate Intercalation Pseudocapacitors

NASA Astrophysics Data System (ADS)

Kong, Lingping; Zhang, Chuanfang; Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

2016-02-01

Li-ion intercalation materials with extremely high rate capability will blur the distinction between batteries and supercapacitors. We construct a series of nanoarchitectured intercalation materials including orthorhombic (o-) Nb2O5 hollow microspheres, o-Nb2O5@carbon core-shell microspheres and tetragonal (t-) NbO2@carbon core-shell microspheres, through a one-pot hydrothermal method with different post-treatments. These nanoarchitectured materials consist of small nanocrystals with highly exposed active surface, and all of them demonstrate good Li+ intercalation pseudocapacitive properties. In particular, o-Nb2O5 hollow microspheres can deliver the specific capacitance of 488.3 F g-1, and good rate performance of 126.7 F g-1 at 50 A g-1. The o-Nb2O5@carbon core-shell microspheres show enhanced specific capacitance of 502.2 F g-1 and much improved rate performance (213.4 F g-1 at 50 A g-1). Furthermore, we demonstrate for the first time, t-NbO2 exhibits much higher rate capability than o-Nb2O5. For discharging time as fast as 5.9 s (50 A g-1), it still exhibits a very high specific capacitance of 245.8 F g-1, which is 65.2% retention of the initial capacitance (377.0 F g-1 at 1 A g-1). The unprecedented rate capability is an intrinsic feature of t-NbO2, which may be due to the conductive lithiated compounds.

Nanoarchitectured Nb2O5 hollow, Nb2O5@carbon and NbO2@carbon Core-Shell Microspheres for Ultrahigh-Rate Intercalation Pseudocapacitors

PubMed Central

Kong, Lingping; Zhang, Chuanfang; Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

2016-01-01

Li-ion intercalation materials with extremely high rate capability will blur the distinction between batteries and supercapacitors. We construct a series of nanoarchitectured intercalation materials including orthorhombic (o-) Nb2O5 hollow microspheres, o-Nb2O5@carbon core-shell microspheres and tetragonal (t-) NbO2@carbon core-shell microspheres, through a one-pot hydrothermal method with different post-treatments. These nanoarchitectured materials consist of small nanocrystals with highly exposed active surface, and all of them demonstrate good Li+ intercalation pseudocapacitive properties. In particular, o-Nb2O5 hollow microspheres can deliver the specific capacitance of 488.3 F g−1, and good rate performance of 126.7 F g−1 at 50 A g−1. The o-Nb2O5@carbon core-shell microspheres show enhanced specific capacitance of 502.2 F g−1 and much improved rate performance (213.4 F g−1 at 50 A g−1). Furthermore, we demonstrate for the first time, t-NbO2 exhibits much higher rate capability than o-Nb2O5. For discharging time as fast as 5.9 s (50 A g−1), it still exhibits a very high specific capacitance of 245.8 F g−1, which is 65.2% retention of the initial capacitance (377.0 F g−1 at 1 A g−1). The unprecedented rate capability is an intrinsic feature of t-NbO2, which may be due to the conductive lithiated compounds. PMID:26880276

Visible-light-driven dynamic cancer therapy and imaging using graphitic carbon nitride nanoparticles.

PubMed

Heo, Nam Su; Lee, Sun Uk; Rethinasabapathy, Muruganantham; Lee, Eun Zoo; Cho, Hye-Jin; Oh, Seo Yeong; Choe, Sang Rak; Kim, Yeonho; Hong, Won G; Krishnan, Giribabu; Hong, Won Hi; Jeon, Tae-Joon; Jun, Young-Si; Kim, Hae Jin; Huh, Yun Suk

2018-09-01

Organic graphitic carbon nitride nanoparticles (NP-g-CN), less than 30 nm in size, were synthesized and evaluated for photodynamic therapy (PDT) and cell imaging applications. NP-g-CN particles were prepared through an intercalation process using a rod-like melamine-cyanuric acid adduct (MCA) as the molecular precursor and a eutectic mixture of LiCl-KCl (45:55 wt%) as the reaction medium for polycondensation. The nano-dimensional NP-g-CN penetrated the malignant tumor cells with minimal hindrance and effectively generated reactive oxygen species (ROS) under visible light irradiation, which could ablate cancer cells. When excited by visible light irradiation (λ > 420 nm), NP-g-CN introduced to HeLa and cos-7 cells generated a significant amount of ROS and killed the cancerous cells selectively. The cytotoxicity of NP-g-CN was manipulated by altering the light irradiation and the BP-g-CN caused more damage to the cancer cells than normal cells at low concentrations. As a potential non-toxic organic nanomaterial, the synthesized NP-g-CN are biocompatible with less cytotoxicity than toxic inorganic materials. The combined effects of the high efficacy of ROS generation under visible light irradiation, low toxicity, and bio-compatibility highlight the potential of NP-g-CN for PDT and imaging without further modification. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of entropy change of lithium intercalation in cathodes and anodes on Li-ion battery thermal management

NASA Astrophysics Data System (ADS)

Viswanathan, Vilayanur V.; Choi, Daiwon; Wang, Donghai; Xu, Wu; Towne, Silas; Williford, Ralph E.; Zhang, Ji-Guang; Liu, Jun; Yang, Zhenguo

The entropy changes (Δ S) in various cathode and anode materials, as well as in complete Li-ion batteries, were measured using an electrochemical thermodynamic measurement system (ETMS). LiCoO 2 has a much larger entropy change than electrodes based on LiNi xCo yMn zO 2 and LiFePO 4, while lithium titanate based anodes have lower entropy change compared to graphite anodes. The reversible heat generation rate was found to be a significant portion of the total heat generation rate. The appropriate combinations of cathode and anode were investigated to minimize reversible heat generation rate across the 0-100% state of charge (SOC) range. In addition to screening for battery electrode materials with low reversible heat, the techniques described in this paper can be a useful engineering tool for battery thermal management in stationary and transportation applications.

Applications of Carbon Nanotubes for Lithium Ion Battery Anodes

PubMed Central

Xiong, Zhili; Yun, Young Soo; Jin, Hyoung-Joon

2013-01-01

Carbon nanotubes (CNTs) have displayed great potential as anode materials for lithium ion batteries (LIBs) due to their unique structural, mechanical, and electrical properties. The measured reversible lithium ion capacities of CNT-based anodes are considerably improved compared to the conventional graphite-based anodes. Additionally, the opened structure and enriched chirality of CNTs can help to improve the capacity and electrical transport in CNT-based LIBs. Therefore, the modification of CNTs and design of CNT structure provide strategies for improving the performance of CNT-based anodes. CNTs could also be assembled into free-standing electrodes without any binder or current collector, which will lead to increased specific energy density for the overall battery design. In this review, we discuss the mechanism of lithium ion intercalation and diffusion in CNTs, and the influence of different structures and morphologies on their performance as anode materials for LIBs. PMID:28809361

Optical signatures of bulk and solutions of KC{sub 8} and KC{sub 24}

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

Tristant, Damien; LPCNO, UMR-5215 CNRS, INSA, Université Fédérale de Toulouse-Midi-Pyrénées, Université de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse; Wang, Yu

2015-07-28

We first performed an analysis of the shape of the Raman features of potassium-intercalated graphite at stage 1 (KC{sub 8} GIC) and 2 (KC{sub 24} GIC), respectively. By varying the excitation energy from ultraviolet to infrared, we observed a sign change of the Fano coupling factor below and above the optical transition related to the shift of the Fermi level which was determined from first principle calculations. This behavior is explained by a sign change in the Raman scattering amplitude of the electronic continuum. The GICs were then dissolved in two different solvents (N-Methyl-2-pyrrolidone and tetrahydrofuran), and the absorbance ofmore » the graphenide solutions obtained was measured in the UV range. Two peaks were observed which correspond to the maximum of the computed imaginary part of the optical index.« less

Two-stage preparation of magnetic sorbent based on exfoliated graphite with ferrite phases for sorption of oil and liquid hydrocarbons from the water surface

NASA Astrophysics Data System (ADS)

Pavlova, Julia A.; Ivanov, Andrei V.; Maksimova, Natalia V.; Pokholok, Konstantin V.; Vasiliev, Alexander V.; Malakho, Artem P.; Avdeev, Victor V.

2018-05-01

Due to the macropore structure and the hydrophobic properties, exfoliated graphite (EG) is considered as a perspective sorbent for oil and liquid hydrocarbons from the water surface. However, there is the problem of EG collection from the water surface. One of the solutions is the modification of EG by a magnetic compound and the collection of EG with sorbed oil using the magnetic field. In this work, the method of the two-stage preparation of exfoliated graphite with ferrite phases is proposed. This method includes the impregnation of expandable graphite in the mixed solution of iron (III) chloride and cobalt (II) or nickel (II) nitrate in the first stage and the thermal exfoliation of impregnated expandable graphite with the formation of exfoliated graphite containing cobalt and nickel ferrites in the second stage. Such two-stage method makes it possible to obtain the sorbent based on EG modified by ferrimagnetic phases with high sorption capacity toward oil (up to 45-51 g/g) and high saturation magnetization (up to 42 emu/g). On the other hand, this method allows to produce the magnetic sorbent in a short period of time (up to 10 s) during which the thermal exfoliation is carried out in the air atmosphere.

Fluid-deposited graphitic inclusions in quartz: Comparison between KTB (German Continental Deep-Drilling) core samples and artificially reequilibrated natural inclusions

USGS Publications Warehouse

Pasteris, J.D.; Chou, I.-Ming

1998-01-01

We used Raman microsampling spectroscopy (RMS) to determine the degree of crystallinity of minute (2-15 ??m) graphite inclusions in quartz in two sets of samples: experimentally reequilibrated fluid inclusions in a natural quartz grain and biotite-bearing paragneisses from the KTB deep drillhole in SE Germany. Our sequential reequilibration experiments at 725??C on initially pure CO2 inclusions in a quartz wafer and the J. Krautheim (1993) experiments at 900-1100??C on organic compounds heated in gold or platinum capsules suggest that, at a given temperature, (1) fluid-deposited graphite will have a lower crystallinity than metamorphosed organic matter and (2) that the crystallinity of fluid-deposited graphite is affected by the composition of the fluid from which it was deposited. We determined that the precipitation of more-crystalline graphite is favored by lower fH2 (higher fO2), and that the crystallinity of graphite is established by the conditions (including gas fugacities) that pertain as the fluid first reaches graphite saturation. Graphite inclusions within quartz grains in the KTB rocks show a wide range in crystallinity index, reflecting three episodes of carbon entrapment under different metamorphic conditions. Isolated graphite inclusions have the spectral properties of totally ordered, completely crystalline graphite. Such crystallinity suggests that the graphite was incorporated from the surrounding metasedimentary rocks, which underwent metamorphism at upper amphibolite-facies conditions. Much of the fluid-deposited graphite in fluid inclusions, however, shows some spectral disorder. The properties of that graphite resemble those of experimental precipitates at temperatures in excess of 700??C and at elevated pressures, suggesting that the inclusions represent precipitates from C-O-H fluids trapped under conditions near those of peak metamorphism at the KTB site. In contrast, graphite that is intimately associated with chlorite and other (presumably low-temperature) silicates in inclusions is highly disordered and spectrally resembles kerogens. This graphite probably was deposited during later greenschist-facies retrograde metamorphism at about 400-500??C. The degree of crystallinity of fluid-deposited graphite is shown to be a much more complex function of temperature than is the crystallinity of metamorphic graphite. To some extent, experiments can provide temperature-calibration of the crystallinity index. However, the difference in time scales between experimental runs and geologic processes makes it difficult to infer specific temperatures for naturally precipitated graphite. Copyright ?? 1998 Elsevier Science Ltd.

Immobilization of paracetamol and benzocaine pro-drug derivatives as long-range self-organized monolayers on graphite.

PubMed

Popoff, Alexandre; Fichou, Denis

2008-05-01

We show here by means of scanning tunneling microscopy (STM) at the liquid/solid interface that paracetamol and benzocaine molecules bearing a long aliphatic chain can be immobilized on highly oriented pyrolitic graphite (HOPG) as perfectly ordered two-dimensional domains extending over several hundreds of nanometers. In both cases, high-resolution STM images reveal that compounds 1 and 2 self-assemble into parallel lamellae having a head-to-head arrangement. The paracetamol heads of 1 are in a zigzag position with entangled n-dodecyloxy side chains while benzocaine heads of compound 2 are perfectly aligned as a double row and have their palmitic side chains on either sides of the head alignment. We attribute the very long-range ordering of these two pro-drug derivatives on HOPG to the combined effects of intermolecular H-bonding on one side and Van der Waals interactions between aliphatic side chains and graphite on the other side. The 2D immobilization of pro-drug derivatives via a non-destructive physisorption mechanism could prove to be useful for applications such as drug delivery if it can be realized on a biocompatible substrate.

O3-type Na(Mn₀.₂₅Fe₀.₂₅Co₀.₂₅Ni₀.₂₅)O₂: a quaternary layered cathode compound for rechargeable Na ion batteries

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

Li, Xi; Zhou, Yong-Ning; Wu, Di

2014-12-01

We report a new layered Na(Mn₀.₂₅Fe₀.₂₅Co₀.₂₅Ni₀.₂₅)O₂ compound with O3 oxygen stacking. It delivers 180 mAh/g initial discharge capacity and 578 Wh/kg specific energy density with good cycling capability at high cutoff voltage. In situ X-ray diffraction (XRD) shows a reversible structure evolution of O3-P3-O3'-O3'' upon Na de-intercalation. The excellent capacity and cycling performance at high cutoff voltage make it an important model system for studying the general issue of capacity fading in layered Na cathode compounds.

Synthesis and characterization of Cd Cr and Zn Cd Cr layered double hydroxides intercalated with dodecyl sulfate

NASA Astrophysics Data System (ADS)

Guo, Ying; Zhang, He; Zhao, Lan; Li, Guo-Dong; Chen, Jie-Sheng; Xu, Lin

2005-06-01

Cd-Cr and Zn-Cd-Cr layered double hydroxides (CdCr-LDH and ZnCdCr-LDH) containing alkyl sulfate as the interlamellar anion have been prepared through a coprecipitation technique. The resulting compounds were characterized using X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Magnetic property measurements indicate that antiferromagnetic interactions occur between the chromium ions in the two compounds at low temperatures. The introduction of zinc influences the ligand field of Cr III and the Cr III-Cr III interactions in the LDH compound. It is found that both CdCr-LDH and ZnCdCr-LDH can be delaminated by dispersion in formamide, leading to translucent and stable colloidal solutions.

Organo/Zn-Al LDH Nanocomposites for Cationic Dye Removal from Aqueous Media

NASA Astrophysics Data System (ADS)

Starukh, G.; Rozovik, O.; Oranska, O.

2016-04-01

Cationic dye sorption by Zn-Al-layered double hydroxides (LDHs) modified with anionic surfactants was examined using methylene blue (MB) dye as a compound model in aqueous solutions. The modification of Zn-Al LDHs was performed by reconstruction method using dodecyl sulfate anion (DS) solutions. DS contained Zn-Al LDHs were characterized by XRD, FTIR, thermogravimetric, and SEM analysis. The reconstructed organo/Zn-Al LDHs comprise the crystalline phases (DS-intercalated LDHs, hydrotalcite), and the amorphous phase. The intercalation of DS ions into the interlayer galleries and DS adsorption on the surface of the LDHs occurred causing the MB adsorption on the external and its sorption in the internal surfaces of modified LDHs. The presence of DS greatly increased the affinity of organo/Zn-Al LDHs for MB due to hydrophobic interactions between the surfactants and the dye molecules. The optical properties of sorbed MB were studied.

The effect of interlayer anion on the reactivity of Mg-Al layered double hydroxides: improving and extending the customization capacity of anionic clays.

PubMed

Rojas, Ricardo; Bruna, Felipe; de Pauli, Carlos P; Ulibarri, M Ángeles; Giacomelli, Carla E

2011-07-01

Layered double hydroxides (LDHs) reactivity and interfacial behavior are closely interconnected and control particle properties relevant to the wide range of these solids' applications. Despite their importance, their relationship has been hardly described. In this work, chloride and dodecylsulfate (DDS(-)) intercalated LDHs are studied combining experimental data (electrophoretic mobility and contact angle measurements, hydroxyl and organic compounds uptake) and a simple mathematical model that includes anion-binding and acid-base reactions. This approach evidences the anion effect on LDHs interfacial behavior, reflected in the opposite particle charge and the different surface hydrophobic/hydrophilic character. LDHs reactivity are also determined by the interlayer composition, as demonstrated by the cation uptake capability of the DDS(-) intercalated sample. Consequently, the interlayer anion modifies the LDHs interfacial properties and reactivity, which in turn extends the customization capacity of these solids. Copyright © 2011 Elsevier Inc. All rights reserved.

Modeling of irradiated graphite (14)C transfer through engineered barriers of a generic geological repository in crystalline rocks.

PubMed

Poskas, Povilas; Grigaliuniene, Dalia; Narkuniene, Asta; Kilda, Raimondas; Justinavicius, Darius

2016-11-01

There are two RBMK-1500 type graphite moderated reactors at the Ignalina nuclear power plant in Lithuania, and they are under decommissioning now. The graphite cannot be disposed of in a near surface repository, because of large amounts of (14)C. Therefore, disposal of the graphite in a geological repository is a reasonable solution. This study presents evaluation of the (14)C transfer by the groundwater pathway into the geosphere from the irradiated graphite in a generic geological repository in crystalline rocks and demonstration of the role of the different components of the engineered barrier system by performing local sensitivity analysis. The speciation of the released (14)C into organic and inorganic compounds as well as the most recent information on (14)C source term was taken into account. Two alternatives were considered in the analysis: disposal of graphite in containers with encapsulant and without it. It was evaluated that the maximal fractional flux of inorganic (14)C into the geosphere can vary from 10(-11)y(-1) (for non-encapsulated graphite) to 10(-12)y(-1) (for encapsulated graphite) while of organic (14)C it was about 10(-3)y(-1) of its inventory. Such difference demonstrates that investigations on the (14)C inventory and chemical form in which it is released are especially important. The parameter with the highest influence on the maximal flux into the geosphere for inorganic (14)C transfer was the sorption coefficient in the backfill and for organic (14)C transfer - the backfill hydraulic conductivity. Copyright © 2016 Elsevier B.V. All rights reserved.

Electronic structure ‘engineering’ in the development of materials for Li-ion and Na-ion batteries

NASA Astrophysics Data System (ADS)

Molenda, Janina

2017-03-01

Transition metal oxides with a general formula A x M a O b (A  =  Li, Na, M  =  transition metal) constitute a group of potential electrode materials for a new generation of alkaline batteries. This application is related to the fact that these compounds can reversibly intercalate high amounts of alkaline ions (1 or more moles per mole of M a O b ) already at room temperature, without significant changes in their crystallographic structure. The author of this work basing on her own investigations of A x M a O b (A  =  Li, Na; M  =  3d, 4d, 5d) has demonstrated that the electronic structure of these materials plays an important role in the intercalation process. Electronic model of intercalation process is presented. Author’s studies show that electronic structure ‘engineering’ is an excellent method of controlling properties of the cathode materials for Li-ion and Na-ion batteries, changing their unfavorable character of the discharge curve, from step-like to monotonic, through modification and control density of states function of a cathode material. Keynote talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

Catalytic Graphitization for Preparation of Porous Carbon Material Derived from Bamboo Precursor and Performance as Electrode of Electrical Double-Layer Capacitor

NASA Astrophysics Data System (ADS)

Tsubota, Toshiki; Maguchi, Yuta; Kamimura, Sunao; Ohno, Teruhisa; Yasuoka, Takehiro; Nishida, Haruo

2015-12-01

The combination of addition of Fe (as a catalyst for graphitization) and CO2 activation (a kind of gaseous activation) was applied to prepare a porous carbon material from bamboo powder (a waste product of superheated steam treatment). Regardless of the heat treatment temperature, many macropores were successfully formed after the heating process by removal of Fe compounds. A turbostratic carbon structure was generated in the Fe-added sample heated at 850°C. It was confirmed that the added Fe acted as a template for pore formation. Moreover, it was confirmed that the added Fe acted as a catalyst for graphitization. The resulting electrochemical performance as the electrode of an electrical double-layer capacitor, as demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy, and charge-discharge testing, could be explained based on the graphitization and activation effects. Addition of Fe could affect the electrical properties of carbon material derived from bamboo.

Proceedings of the Scientific Conference on Obscuration and Aerosol Research Held in Aberdeen Proving Ground, Maryland on 17-21 June 1985.

DTIC Science & Technology

1986-07-01

Aerosols:Science, Technoloy ..and Industrial Aplications . Els-!vier NY, 1984. T. H. Tsang and J. R. Brock. "On Cstwald ripening", in B.Y.H. Liu et al...of Small Glass Particles Spouted in Water", Ph.D. Thesis , Rensselaer Polytechnic Institute, Troy, NY (1982). Table I Comparison of Predicted and...carrier densities and mobilities of graphite, copper, and second stage AsF 5 compound. The carrier den- sity of graphite is very low (l carrier for 10 atoms

Spin-glass freezing in a Ni-vermiculite intercalation compound.

PubMed

Marcos, C; Argüelles, A; Khainakov, S A; Rodríguez Fernández, J; Blanco, J A

2012-08-29

We report on the magnetic properties of a Ni(2+)-vermiculite intercalation compound from Santa Olalla, Huelva (Spain). This modified vermiculite was studied by means of DC and AC magnetic measurements. The existence of two maxima in magnetic susceptibility below 10 K was interpreted in terms of the Cole-Cole formalism as being due to spin-glass freezing in this material. The temperature, frequency and external magnetic field dependences of these anomalies located at temperatures around 2-3 K and 8-10 K in the imaginary part of the magnetic susceptibility, χ″, seem to suggest the existence of spin-relaxation phenomena between the magnetic moments of the Ni(2+) ions. A dynamic study of the relaxation processes associated with these phenomena considering the Cole-Cole formalism allows us to interpret the anomaly found at 2-3 K according to a law of activated dynamics, obtaining values for the critical exponent, ψν < 1, characteristic of a d = 2 spin-glass-like system, while the maximum observed in χ″ at 8-10 K can be described by means of a law of standard dynamics with a value of the exponent z of around 5, representative of a d = 3 spin-glass-like system.

Atomic hydrogen storage method and apparatus

NASA Technical Reports Server (NTRS)

Woollam, J. A. (Inventor)

1978-01-01

Atomic hydrogen, for use as a fuel or as an explosive, is stored in the presence of a strong magnetic field in exfoliated layered compounds such as molybdenum disulfide or an elemental layer material such as graphite. The compound is maintained at liquid helium temperatures and the atomic hydrogen is collected on the surfaces of the layered compound which are exposed during delamination (exfoliation). The strong magnetic field and the low temperature combine to prevent the atoms of hydrogen from recombining to form molecules.

Atomic hydrogen storage method and apparatus

NASA Technical Reports Server (NTRS)

Woollam, J. A. (Inventor)

1980-01-01

Atomic hydrogen, for use as a fuel or as an explosive, is stored in the presence of a strong magnetic field in exfoliated layered compounds such as molybdenum disulfide or an elemental layer material such as graphite. The compounds maintained at liquid helium temperatures and the atomic hydrogen is collected on the surfaces of the layered compound which are exposed during delamination (exfoliation). The strong magnetic field and the low temperature combine to prevent the atoms of hydrogen from recombining to form molecules.

Atomic hydrogen storage. [cryotrapping and magnetic field strength

NASA Technical Reports Server (NTRS)

Woollam, J. A. (Inventor)

1980-01-01

Atomic hydrogen, for use as a fuel or as an explosive, is stored in the presence of a strong magnetic field in exfoliated layered compounds such as molybdenum disulfide or an elemental layer material such as graphite. The compound is maintained at liquid temperatures and the atomic hydrogen is collected on the surfaces of the layered compound which are exposed during delamination (exfoliation). The strong magnetic field and the low temperature combine to prevent the atoms of hydrogen from recombining to form molecules.

Application of organic compounds for high-order harmonic generation of ultrashort pulses

NASA Astrophysics Data System (ADS)

Ganeev, R. A.

2016-02-01

The studies of the high-order nonlinear optical properties of a few organic compounds (polyvinyl alcohol, polyethylene, sugar, coffee, and leaf) are reported. Harmonic generation in the laser-produced plasmas containing the molecules and large particles of above materials is demonstrated. These studies showed that the harmonic distributions and harmonic cutoffs from organic compound plasmas were similar to those from the graphite ablation. The characteristic feature of observed harmonic spectra was the presence of bluesided lobes near the lower-order harmonics.

Small molecule glycoconjugates with anticancer activity.

PubMed

Pastuch-Gawołek, Gabriela; Malarz, Katarzyna; Mrozek-Wilczkiewicz, Anna; Musioł, Marta; Serda, Maciej; Czaplinska, Barbara; Musiol, Robert

2016-04-13

Glycoconjugates are combinations of sugar moieties with organic compounds. Due to their biological resemblance, such structures often have properties that are desirable for drugs. In this study we designed and synthesised several glycoconjugates from small molecular quinolines and substituted gluco- and galactopyranosyl amines. Although the parent quinoline compounds were inactive in affordable concentrations, the glycoconjugates that were obtained appeared to be cytotoxic against cancer cells at the micromolar level. When combined with copper ions, their activity increased even further. Their mechanism of action is connected to the formation of reactive oxygen species and the intercalation of DNA. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Isolation and characterization of nanosheets containing few layers of the Aurivillius family of oxides and metal-organic compounds

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

Sreedhara, M.B.; Prasad, B.E.; Moirangthem, Monali

2015-04-15

Nanosheets containing few-layers of ferroelectric Aurivillius family of oxides, Bi{sub 2}A{sub n−1}B{sub n}O{sub 3n+3} (where A=Bi{sup 3+}, Ba{sup 2+} etc. and B=Ti{sup 4+}, Fe{sup 3+} etc.) with n=3, 4, 5, 6 and 7 have been prepared by reaction with n-butyllithium, followed by exfoliation in water. The few-layer samples have been characterized by Tyndall cones, atomic force microscopy, optical spectroscopy and other techniques. The few-layer species have a thickness corresponding to a fraction of the c-parameter along which axis the perovskite layers are stacked. Magnetization measurements have been carried out on the few-layer samples containing iron. Few-layer species of a fewmore » layered metal-organic compounds have been obtained by ultrasonication and characterized by Tyndall cones, atomic force microscopy, optical spectroscopy and magnetic measurements. Significant changes in the optical spectra and magnetic properties are found in the few-layer species compared to the bulk samples. Few-layer species of the Aurivillius family of oxides may find uses as thin layer dielectrics in photovoltaics and other applications. - Graphical abstract: Exfoliation of the layered Aurivillius oxides into few-layer nanosheets by chemical Li intercalation using n-BuLi followed by reaction in water. Exfoliation of the layered metal-organic compounds into few-layer nanosheets by ultrasonication. - Highlights: • Few-layer nanosheets of Aurivillius family of oxides with perovskite layers have been generated by lithium intercalation. • Few-layer nanosheets of few layered metal-organic compounds have been generated by ultrasonication. • Few-layer nanosheets of the Aurivillius oxides have been characterized by AFM, TEM and optical spectroscopy. • Aurivillius oxides containing Fe show layer dependent magnetic properties. • Exfoliated few-layer metal-organic compounds show changes in spectroscopic and magnetic properties compared with bulk materials.« less

Azapsoralens: new potential photochemotherapeutic agents for psoriasis.

PubMed

Vedaldi, D; Caffieri, S; Miolo, G; Dall'Acqua, F; Baccichetti, F; Guiotto, A; Benetollo, F; Bombieri, G; Recchia, G; Cristofolini, M

1991-12-01

New bioisoters of psoralen, obtained by replacing carbon 8 of the central benzene ring with a nitrogen, were studied from the photochemical, photobiological and phototherapeutic points of view. In particular, 4,4'-, 4',5'-dimetyl, 4,4',5'-trimethyl and 3,4,4',5'-tetramethylazapsoralen were studied. The crystal and molecular structure of 4,4',5'-trimethylazapsoralen, obtained by X ray diffraction, was also reported. Like psoralen, these compounds form a molecular complex with DNA, undergoing intercalation inside the double helix of the macromolecule. When irridiated with long ultraviolet light (365 nm), the intercalated drug photoconjugates covalently to the macromolecule, forming mono- and diadducts. The photobinding rate show the following order of magnitude: 4,4',5'-trimetylazapsoralen (4,4',5'-TMAP) = 3,4,4',5'-tetramethylazapsoralen (3,4,4',5'-TMAP) greater than 4',5'-dimethylazapsoralen (4',5'-DMAP) = 4,4'-dimethylazapsoralen (4,4'-DMAP). The DNA photobinding rate of 8-methoxypsoralen (8-MOP), taken as reference compound, is similar to that of the two dimetylazapsoralens but lower than tri- and tetramethyl derivatives. The ability of azapsoralens to form cross-links in DNA is lower than that of 8-MOP. However, capacity to induce cross-links does not parallel the DNA photobinding rate; it is higher for trimethyl derivate and lower for tetramethylazapsoralen. Azapsoralens show evident antiproliferative activity. The trimethyl derivative is the most active, followed by tetrametyl, both these compounds showing activity slightly higher than that of 8-MOP. The two dimethylderivatives are less active. The mautagenic activity of azapsoralens on E. coli WP2 TM6 is lower than that of 8-MOP in the same conditions. The new compounds do not show any skin phototoxicity on guinea pig skin. On the basis of its DNA photobinding, antiproliferative activity, mutagenicity and lack of skin phototoxicity, 4,4',5'-TMAP was chosen for clinical evaluation. Clinical results obtained by topical treatment of psoriatic plaques reveal evident therapeutic effectiveness and clearing is between good and moderate, although 8-MOP, used as reference compound, is more effective.

Determination of ruthenium in pharmaceutical compounds by graphite furnace atomic absorption spectroscopy.

PubMed

Jia, Xiujuan; Wang, Tiebang; Bu, Xiaodong; Tu, Qiang; Spencer, Sandra

2006-04-11

A graphite furnace atomic absorption (GFAA) spectrometric method for the determination of ruthenium (Rh) in solid and liquid pharmaceutical compounds has been developed. Samples are dissolved or diluted in dimethyl sulfoxide (DMSO) without any other treatment before they were analyzed by GFAA with a carefully designed heating program to avoid pre-atomization signal loss and to achieve suitable sensitivity. Various inorganic and organic solvents were tested and compared and DMSO was found to be the most suitable. In addition, ruthenium was found to be stable in DMSO for at least 5 days. Spike recoveries ranged from 81 to 100% and the limit of quantitation (LOQ) was determined to be 0.5 microg g(-1) for solid samples or 0.005 microg ml(-1) for liquid samples based a 100-fold dilution. The same set of samples was also analyzed by ICP-MS with a different sample preparation method, and excellent agreement was achieved.

Composite glycerol/graphite/aromatic acid matrices for thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry of heterocyclic compounds.

PubMed

Esparza, Cesar; Borisov, R S; Varlamov, A V; Zaikin, V G

2016-10-28

New composite matrices have been suggested for the analysis of mixtures of different synthetic organic compounds (N-containing heterocycles and erectile dysfunction drugs) by thin layer chromatography/matrix-assisted laser desorption ionization time-of-flight mass spectrometry (TLC/MALDI-TOF). Different mixtures of classical MALDI matrices and graphite particles dispersed in glycerol were used for the registration of MALDI mass spectra directly from TLC plates after analytes separation. In most of cases, the mass spectra possessed [M+H] + ions; however, for some analytes only [M+Na] + and [M+K] + ions were observed. These ions have been used to generate visualized TLC chromatograms. The described approach increases the desorption/ionization efficiencies of analytes separated by TLC, prevent spot blurring, simplifies and decrease time for sample preparation. Copyright © 2016 Elsevier B.V. All rights reserved.

Anticancer Activity Expressed by a Library of 2,9-Diazaperopyrenium Dications

PubMed Central

2016-01-01

Polyaromatic compounds are well-known to intercalate DNA. Numerous anticancer chemotherapeutics have been developed upon the basis of this recognition motif. The compounds have been designed such that they interfere with the role of the topoisomerases, which control the topology of DNA during the cell-division cycle. Although many promising chemotherapeutics have been developed upon the basis of polyaromatic DNA intercalating systems, these candidates did not proceed past clinical trials on account of their dose-limiting toxicity. Herein, we discuss an alternative, water-soluble class of polyaromatic compounds, the 2,9-diazaperopyrenium dications, and report in vitro cell studies for a library of these dications. These investigations reveal that a number of 2,9-diazaperopyrenium dications show similar activities as doxorubicin toward a variety of cancer cell lines. Additionally, we report the solid-state structures of these dications, and we relate their tendency to aggregate in solution to their toxicity profiles. The addition of bulky substituents to these polyaromatic dications decreases their tendency to aggregate in solution. The derivative substituted with 2,6-diisopropylphenyl groups proved to be the most cytotoxic against the majority of the cell lines tested. In the solid state, the 2,6-diisopropylphenyl-functionalized derivative does not undergo π···π stacking, while in aqueous solution, dynamic light scattering reveals that this derivative forms very small (50–100 nm) aggregates, in contrast with the larger ones formed by dications with less bulky substituents. Alteration of the aromaticitiy in the terminal heterocycles of selected dications reveals a drastic change in the toxicity of these polyaromatic species toward specific cell lines. PMID:25555133

Synthesis and characterization of new unsymmetrical Schiff base Zn (II) and Co (II) complexes and study of their interactions with bovin serum albumin and DNA by spectroscopic techniques.

PubMed

Sedighipoor, Maryam; Kianfar, Ali Hossein; Sabzalian, Mohammad R; Abyar, Fatemeh

2018-06-05

Two novel tetra-coordinated Cobalt(II) and Zinc (II) chelate series with the general formula of [Co (L)·2H 2 O] (1) and [Zn (L)] (2) [L=N-2-hydroxyacetophenon-N'-2-hydroxynaphthaldehyde-1,2 phenylenediimine)] with biologically active Schiff base ligands were synthesized and recognized by elemental analysis and multi-nuclear spectroscopy (IR and 1 H and 13 C NMR); then, their biological activities including DNA and protein interactions were studied. The interaction of the synthesized compounds with bovine serum albumin (BSA) was investigated via fluorescence spectroscopy, showing the affinity of the complexes for these proteins with relatively high binding constant values and the changed secondary BSA structure in the presence of the complexes. The interaction of these compounds with CT-DNA was considered by UV-Vis technique, emission titration, viscosity measurements, helix melting methods, and circular dichroism (CD) spectroscopy, confirming that the complexes were bound to CT-DNA by the intercalation binding mode. Furthermore, the complexes had the capability to displace the DNA-bound MB, as shown by the competitive studies of these complexes with methylene blue (MB), thereby suggesting the intercalation mode for the competition. Finally, the theoretical studies carried out by the docking method were performed to calculate the binding constants and recognize the binding site of the BSA and DNA by the complexes. In addition, in vitro and in silico studies showed that the compounds were degradable by bacterial and fungal biodegradation activities. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis and characterization of new unsymmetrical Schiff base Zn (II) and Co (II) complexes and study of their interactions with bovin serum albumin and DNA by spectroscopic techniques

NASA Astrophysics Data System (ADS)

Sedighipoor, Maryam; Kianfar, Ali Hossein; Sabzalian, Mohammad R.; Abyar, Fatemeh

2018-06-01

Two novel tetra-coordinated Cobalt(II) and Zinc (II) chelate series with the general formula of [Co (L)·2H2O] (1) and [Zn (L)] (2) [L = N-2-hydroxyacetophenon-N‧-2-hydroxynaphthaldehyde-1,2 phenylenediimine)] with biologically active Schiff base ligands were synthesized and recognized by elemental analysis and multi-nuclear spectroscopy (IR and 1H and 13C NMR); then, their biological activities including DNA and protein interactions were studied. The interaction of the synthesized compounds with bovine serum albumin (BSA) was investigated via fluorescence spectroscopy, showing the affinity of the complexes for these proteins with relatively high binding constant values and the changed secondary BSA structure in the presence of the complexes. The interaction of these compounds with CT-DNA was considered by UV-Vis technique, emission titration, viscosity measurements, helix melting methods, and circular dichroism (CD) spectroscopy, confirming that the complexes were bound to CT-DNA by the intercalation binding mode. Furthermore, the complexes had the capability to displace the DNA-bound MB, as shown by the competitive studies of these complexes with methylene blue (MB), thereby suggesting the intercalation mode for the competition. Finally, the theoretical studies carried out by the docking method were performed to calculate the binding constants and recognize the binding site of the BSA and DNA by the complexes. In addition, in vitro and in silico studies showed that the compounds were degradable by bacterial and fungal biodegradation activities.

Synthesis and electrochemical characterization of Silicon clathrates as anode materials for Lithium ion batteries

NASA Astrophysics Data System (ADS)

Raghavan, Rahul

Novel materials for Li-ion batteries is one of the principle thrust areas for current research in energy storage, more so than most, considering its widespread use in portable electronic gadgets and plug-in electric and hybrid cars. One of the major limiting factors in a Li-ion battery's energy density is the low specific capacities of the active materials in the electrodes. In the search for high-performance anode materials for Li-ion batteries, many alternatives to carbonaceous materials have been studied. Both cubic and amorphous silicon can reversibly alloy with lithium and have a theoretical capacity of 3500 mAh/g, making silicon a potential high density anode material. However, a large volume expansion of 300% occurs due to changes in the structure during lithium insertion, often leading to pulverization of the silicon. To this end, a class of silicon based cage compounds called clathrates are studied for electrochemical reactivity with lithium. Silicon-clathrates consist of silicon covalently bonded in cage structures comprised of face sharing Si20, Si24 and/or Si28 clusters with guest ions occupying the interstitial positions in the polyhedra. Prior to this, silicon clathrates have been studied primarily for their superconducting and thermoelectric properties. In this work, the synthesis and electrochemical characterization of two categories of silicon clathrates - Type-I silicon clathrate with aluminum framework substitution and barium guest ions (Ba8AlxSi46-x) and Type-II silicon clathrate with sodium guest ions (Nax Si136), are explored. The Type-I clathrate, Ba8AlxSi46-x consists of an open framework of aluminium and silicon, with barium (guest) atoms occupying the interstitial positions. X-ray diffraction studies have shown that a crystalline phase of clathrate is obtained from synthesis, which is powdered to a fine particle size to be used as the anode material in a Li-ion battery. Electrochemical measurements of these type of clathrates have shown that capacities comparable to graphite can be obtained for up to 10 cycles and lower capacities can be obtained for up to 20 cycles. Unlike bulk silicon, the clathrate structure does not undergo excessive volume change upon lithium intercalation, and therefore, the crystal structure is morphologically stable over many cycles. X-ray diffraction of the clathrate after cycling showed that crystallinity is intact, indicating that the clathrate does not collapse during reversible intercalation with lithium ions. Electrochemical potential spectroscopy obtained from the cycling data showed that there is an absence of formation of lithium-silicide, which is the product of lithium alloying with diamond cubic silicon. Type II silicon clathrate, NaxSi136, consists of silicon making up the framework structure and sodium (guest) atoms occupying the interstitial spaces. These clathrates showed very high capacities during their first intercalation cycle, in the range of 3,500 mAh/g, but then deteriorated during subsequent cycles. X-ray diffraction after one cycle showed the absence of clathrate phase and the presence of lithium-silicide, indicating the disintegration of clathrate structure. This could explain the silicon-like cycling behavior of Type II clathrates.

Breakdown voltage reliability improvement in gas-discharge tube surge protectors employing graphite field emitters

NASA Astrophysics Data System (ADS)

Žumer, Marko; Zajec, Bojan; Rozman, Robert; Nemanič, Vincenc

2012-04-01

Gas-discharge tube (GDT) surge protectors are known for many decades as passive units used in low-voltage telecom networks for protection of electrical components from transient over-voltages (discharging) such as lightning. Unreliability of the mean turn-on DC breakdown voltage and the run-to-run variability has been overcome successfully in the past by adding, for example, a radioactive source inside the tube. Radioisotopes provide a constant low level of free electrons, which trigger the breakdown. In the last decades, any concept using environmentally harmful compounds is not acceptable anymore and new solutions were searched. In our application, a cold field electron emitter source is used as the trigger for the gas discharge but with no activating compound on the two main electrodes. The patent literature describes in details the implementation of the so-called trigger wires (auxiliary electrodes) made of graphite, placed in between the two main electrodes, but no physical explanation has been given yet. We present experimental results, which show that stable cold field electron emission current in the high vacuum range originating from the nano-structured edge of the graphite layer is well correlated to the stable breakdown voltage of the GDT surge protector filled with a mixture of clean gases.

Formation of stable nanocomposite clays from small peptides reacted with montmorillonite and illite-smectite mixed layer clays

NASA Astrophysics Data System (ADS)

Block, K. A.; Katz, A.; LeBlanc, J.; Peña, S.; Gottlieb, P.

2015-12-01

Understanding how organic compounds interact with clay minerals and which functional groups result in the strongest bonds is pivotal to achieving a better understanding of how mineral composition affects the residence time of carbon and nitrogen in soils. In this work, we describe how small peptides derived from tryptone casein digest are dissolved and suspended with clay minerals to examine the nature of OM adsorption to mineral surfaces and the resulting effect on clay mineral structure. XRD analyses indicate that peptides intercalation results in expansion of the d001 spacing of montmorillonite (Mt) and the smectite component of a 70-30 illite-smectite mixed layer clay (I-S) and poorer crystallinity overall as a result of exfoliation of tactoids. Peptide adsorption is concentration-dependent, however, surface adsorption appears to mediate interlayer adsorption in Mt reaching a maximum of 16% of the mass of the organoclay complex, indicating that at a critical concentration, peptide intercalation will supersede surface adsorption resulting in a more stable attachment. In I-S the degree of surface adsorption and intercalation is proportional to concentration, however, surface adsorption is not a priming mechanism for interlayer adsorption. Thermogravimetric analysis of the organoclay complexes determined by TGA coupled to GC-MS indicate that the most prominent product species measured was 1-(1-Trimethylsiloxyethenyl)-3-trimethylsiloxy-benzene, likely from tryptophan monomer decomposition. The compound was detected over a broad temperature range, greater than 300 oC, during pyrolysis and suggests a carbon-silicon covalent bond formed between the peptide and tetrahedral layers in the clay. An additional silicon-bearing VOC detected at lower pyrolysis temperature by GC was N,N-Diethyl-1-(trimethylsilyl)-9,10-didehydroergoline-8-carboxamide, likely derived from a lysine-bearing peptide derivative. We hypothesize that hydrophobic (non-ionic) peptides react with silanol at the clay platelet edges to induce exfoliation and subsequent formation of stable nanocomposite clays.

Investigation of the matrix effect in determining microimpurities in boron and its compounds by atomic-emission spectrometry

NASA Astrophysics Data System (ADS)

Lebedeva, R. V.; Tumanova, A. N.; Mashin, N. I.

2007-07-01

We carried out a systematic study of the influence of the main component on the change of analytical signal during atomic-emission analysis of boron compounds. Changes in the intensity of spectral lines of microimpurities as functions of their concentrations in the analytical system based on graphite powder with a variable content of boric acid and boron oxide are presented.

Plasmaron excitations in p(2×2)-K/graphite

NASA Astrophysics Data System (ADS)

Chis, V.; Silkin, V. M.; Hellsing, B.

2014-05-01

Plasmarons formed by the compound of photoelectrons and acoustic surface-plasmon excitations is investigated in the system p(2×2)-K/graphite. The physics behind this type of plasmarons (e plasmarons) differs from the physics of plasmarons recently found in graphene, where the loss feature is argued to result from the photohole-plasmon interaction (h plasmarons). Based on first principles methods we calculate the dispersion of the e-plasmaron excitation rate, which yields a broad feature below the parabolic quantum-well band with a peak about 0.4 eV below the quantum-well band at the Γ¯ point.

Enhanced thermoelectric performance in Cu-intercalated BiTeI by compensation weakening induced mobility improvement

DOE PAGES

Wu, Lihua; Yang, Jiong; Chi, Miaofang; ...

2015-09-23

The low weighted carrier mobility has long been considered to be the key challenge for improvement of thermoelectric (TE) performance in BiTeI. The Rashba-effect-induced two-dimensional density of states in this bulk semiconductor is beneficial for thermopower enhancement, which makes it a prospective compound for TE applications. In this report, we show that intercalation of minor Cu-dopants can substantially alter the equilibria of defect reactions, selectively mediate the donor-acceptor compensation, and tune the defect concentration in the carrier conductive network. Consequently, the potential fluctuations responsible for electron scattering are reduced and the carrier mobility in BiTeI can be enhanced by amore » factor of two to three between 10 K and 300 K. The carrier concentration can also be optimized by tuning the Te/I composition ratio, leading to higher thermopower in this Rashba system. Cu-intercalation in BiTeI gives rise to higher power factor, slightly lower lattice thermal conductivity, and consequently improved figure of merit. Compared with pristine BiTe 0.98I 1.02, the TE performance in Cu 0.05BiTeI reveals a 150% and 20% enhancement at 300 and 520 K, respectively. Ultimately, these results demonstrate that defect equilibria mediated by selective doping in complex TE and energy materials could be an effective approach to carrier mobility and performance optimization.« less

Tribological Characteristics of Submicron SiC(p)-GR(p)/Zn-35Al-1Mg Composites in Semisolidification Casting process

NASA Astrophysics Data System (ADS)

Liu, S.; Fang, Z. W.; Li, L. X.

2018-05-01

Uniform SiC(p)-GR(p)/Zn-35Al-1Mg composites were prepared by powder pressing and semisolidification stirring-casting process by adding submicron silicon carbide and graphite reinforcement particles in an aluminum-zinc alloy matrix. Micro Vickers hardness and microstructures of the novel composites were studied, and their wear properties and wear temperature were measured for different load and friction conditions. The results show that silicon carbide and graphite particles homogeneously mix in the matrix, while contained silicon carbide particles improve the matrix hardness to 8.4%, graphite improves the matrix hardness to 16.8%, but two of them, combined, reduce the matrix hardness to 7.6%; the rate of temperature rise of the zinc-aluminum matrix alloy is the highest than the other three composites and is up to 48.5° C/s at 1.69MPa. At 0.56MPa and sliding 26.4km, the graphite composite anti-wear effect is optimal, while at 1.13MPa, the wear resistance of silicon carbide and graphite compound particles is the best; in the other case of only silicon carbide particles, the wear resistance is increased to 35% at 1.69MPa and 26.4km, and its anti-wear effects are excellent.

The intercalation chemistry of layered iron chalcogenide superconductors

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

Vivanco, Hector K.; Rodriguez, Efrain E., E-mail: efrain@umd.edu

The iron chalcogenides FeSe and FeS are superconductors composed of two-dimensional sheets held together by van der Waals interactions, which makes them prime candidates for the intercalation of various guest species. We review the intercalation chemistry of FeSe and FeS superconductors and discuss their synthesis, structure, and physical properties. Before we review the latest work in this area, we provide a brief background on the intercalation chemistry of other inorganic materials that exhibit enhanced superconducting properties upon intercalation, which include the transition metal dichalcogenides, fullerenes, and layered cobalt oxides. From past studies of these intercalated superconductors, we discuss the rolemore » of the intercalates in terms of charge doping, structural distortions, and Fermi surface reconstruction. We also briefly review the physical and chemical properties of the host materials—mackinawite-type FeS and β-FeSe. The three types of intercalates for the iron chalcogenides can be placed in three categories: 1.) alkali and alkaline earth cations intercalated through the liquid ammonia technique; 2.) cations intercalated with organic amines such as ethylenediamine; and 3.) layered hydroxides intercalated during hydrothermal conditions. A recurring theme in these studies is the role of the intercalated guest in electron doping the chalcogenide host and in enhancing the two-dimensionality of the electronic structure by spacing the FeSe layers apart. We end this review discussing possible new avenues in the intercalation chemistry of transition metal monochalcogenides, and the promise of these materials as a unique set of new inorganic two-dimensional systems.« less

Cohesive Energies of Some Transition Metal Compounds Using Embedded Clusters

NASA Astrophysics Data System (ADS)

Press, Mehernosh Rustom

The molecular-clusters approach to electronic structure calculation is especially well-suited to the study of properties that depend primarily on the local environment of a system, especially those with no translational symmetry, e.g. systems with defects and structural deformations. The presence of the rest of the crystal environment can be accounted for approximately by embedding the cluster in a self-consistent crystal potential. This thesis makes a contribution in the area of investigating the capability of embedded molecular-clusters to yield reliable bulk structural properties. To this end, an algorithm for calculating the cohesive energies of clusters within the discrete-variational X(,(alpha)) LCAO-MO formulation is set up and verified on simple solids: Li, Na, Cu and LiF. We then use this formulation to study transition metal compounds, for which the interesting physics lies in local lattice defects, foreign impurities and structural deformations. In a self -consistent calculation of the lattice energies and stability of defect clusters in wustite, Fe(,1-x)O, corner-sharing aggregates of the 4:1 defect are identified as the most stable defect configurations due to efficient compensation of the cluster charge. The intercalation properties of layered-transition-metal-dichalcogenides continues to be a fertile experimental working area, backed by comparatively little theoretical study. We find that intercalation of ZrS(,2) with Na perturbs the valence energy level structure sufficiently to induce a more ionic Zr-S bond, a narrowing of the optical gap and filling of the lowest unoccupied host lattice orbitals with the electron donated by Na. Fe - intercalation in ZrS(,2) is accommodated via a strong Fe-S bond, impurity-like band levels in the optical gap of the host and hybridization-driven compression and lowering of the conduction band energy levels. The piezoelectric cuprous halides, CuCl and CuBr, exhibit a host of intriguing properties due to a filled and very active d('10) shell at the Fermi energy. A self-consistent calculation via energy minimization of the internal strain in these compounds shows both Cu-halide bonds to be very rigid with little charge delocalization under strain. Piezoelectric response is calculated in terms of effective charges and quadrupolar moments, e(,T) and (DELTA)Q.

Photoinduced Electron Transfer between Psoralens and DNA: Influence of DNA Sequence and Substitution.

PubMed

Fröbel, Sascha; Levi, Lucilla; Ulamec, Sabine M; Gilch, Peter

2016-05-04

Psoralens are heterocyclic compounds which are, among other uses, used to treat skin deseases in the framework of PUVA therapy. In the dark, they intercalate into DNA and can form photoadducts with thymines upon UV-A excitation, which harms the affected cells. We have recently discovered that after excitation of intercalated psoralens, an efficient photoinduced electron transfer (PET) from DNA occurs. Here, the PET is studied in detail by means of femtosecond transient absorption spectroscopy. Using DNA samples that contain either only GC or AT base pairs, we show that only guanine donates the electrons. Additionally, the substituent effects on PET are studied relying on three different psoralen derivatives. The substitution alters spectroscopic and electrochemical properties of the psoralens, which are determined by cyclic voltammetry and steady state spectroscopy. These experiments allow us to estimate the PET energetics, which are in line with the measured kinetics. Implications for the applications of psoralens are discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sign reversal of the order parameter in (Li1-xFex)OHFe1-yZnySe

NASA Astrophysics Data System (ADS)

Du, Zengyi; Yang, Xiong; Altenfeld, Dustin; Gu, Qiangqiang; Yang, Huan; Eremin, Ilya; Hirschfeld, Peter J.; Mazin, Igor I.; Lin, Hai; Zhu, Xiyu; Wen, Hai-Hu

2018-02-01

Iron pnictides are the only known family of unconventional high-temperature superconductors besides cuprates. Until recently, it was widely accepted that superconductivity is driven by spin fluctuations and intimately related to the fermiology, specifically, hole and electron pockets separated by the same wavevector that characterizes the dominant spin fluctuations, and supporting order parameters (OP) of opposite signs. This picture was questioned after the discovery of intercalated or monolayer form of FeSe-based systems without hole pockets, which seemingly undermines the basis for spin-fluctuation theory and the idea of a sign-changing OP. Using the recently proposed phase-sensitive quasiparticle interference technique, here we show that in LiOH-intercalated FeSe compound the OP does change sign, albeit within the electronic pockets. This result unifies the pairing mechanism of iron-based superconductors with or without the hole Fermi pockets and supports the conclusion that spin fluctuations play the key role in electron pairing.

Liquid-like thermal conduction in intercalated layered crystalline solids

DOE PAGES

Li, B.; Wang, H.; Kawakita, Y.; ...

2018-01-15

As a generic property, all substances transfer heat through microscopic collisions of constituent particles. A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here in this work, we report liquid-like thermal conduction observed in the crystalline AgCrSe 2. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive,more » and are thus responsible for the intrinsically ultralow thermal conductivity. This scenario is applicable to a wide variety of layered compounds with heavy intercalants in the van der Waals gaps, manifesting a broad implication on suppressing thermal conduction. Finally, these microscopic insights might reshape the fundamental understanding on thermal transport properties of matter and open up a general opportunity to optimize performances of thermoelectrics.« less

Liquid-like thermal conduction in intercalated layered crystalline solids

NASA Astrophysics Data System (ADS)

Li, B.; Wang, H.; Kawakita, Y.; Zhang, Q.; Feygenson, M.; Yu, H. L.; Wu, D.; Ohara, K.; Kikuchi, T.; Shibata, K.; Yamada, T.; Ning, X. K.; Chen, Y.; He, J. Q.; Vaknin, D.; Wu, R. Q.; Nakajima, K.; Kanatzidis, M. G.

2018-03-01

As a generic property, all substances transfer heat through microscopic collisions of constituent particles1. A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations2,3. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here, we report liquid-like thermal conduction observed in the crystalline AgCrSe2. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive, and are thus responsible for the intrinsically ultralow thermal conductivity. This scenario is applicable to a wide variety of layered compounds with heavy intercalants in the van der Waals gaps, manifesting a broad implication on suppressing thermal conduction. These microscopic insights might reshape the fundamental understanding on thermal transport properties of matter and open up a general opportunity to optimize performances of thermoelectrics.

Activation of cGAS-dependent antiviral responses by DNA intercalating agents

PubMed Central

Pépin, Geneviève; Nejad, Charlotte; Thomas, Belinda J.; Ferrand, Jonathan; McArthur, Kate; Bardin, Philip G.; Williams, Bryan R.G.; Gantier, Michael P.

2017-01-01

Acridine dyes, including proflavine and acriflavine, were commonly used as antiseptics before the advent of penicillins in the mid-1940s. While their mode of action on pathogens was originally attributed to their DNA intercalating activity, work in the early 1970s suggested involvement of the host immune responses, characterized by induction of interferon (IFN)-like activities through an unknown mechanism. We demonstrate here that sub-toxic concentrations of a mixture of acriflavine and proflavine instigate a cyclic-GMP-AMP (cGAMP) synthase (cGAS)-dependent type-I IFN antiviral response. This pertains to the capacity of these compounds to induce low level DNA damage and cytoplasmic DNA leakage, resulting in cGAS-dependent cGAMP-like activity. Critically, acriflavine:proflavine pre-treatment of human primary bronchial epithelial cells significantly reduced rhinovirus infection. Collectively, our findings constitute the first evidence that non-toxic DNA binding agents have the capacity to act as indirect agonists of cGAS, to exert potent antiviral effects in mammalian cells. PMID:27694309

Liquid-like thermal conduction in intercalated layered crystalline solids

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

Li, B.; Wang, H.; Kawakita, Y.

As a generic property, all substances transfer heat through microscopic collisions of constituent particles. A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here in this work, we report liquid-like thermal conduction observed in the crystalline AgCrSe 2. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive,more » and are thus responsible for the intrinsically ultralow thermal conductivity. This scenario is applicable to a wide variety of layered compounds with heavy intercalants in the van der Waals gaps, manifesting a broad implication on suppressing thermal conduction. Finally, these microscopic insights might reshape the fundamental understanding on thermal transport properties of matter and open up a general opportunity to optimize performances of thermoelectrics.« less

Sodium intercalation in the phosphosulfate cathode NaFe2(PO4)(SO4)2

NASA Astrophysics Data System (ADS)

Ben Yahia, Hamdi; Essehli, Rachid; Amin, Ruhul; Boulahya, Khalid; Okumura, Toyoki; Belharouak, Ilias

2018-04-01

The compound NaFe2(PO4)(SO4)2 is successfully synthesized via a solid state reaction route and its crystal structure is determined using powder X-ray diffraction data. NaFe2(PO4)(SO4)2 phase is also characterized by cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy. NaFe2(PO4)(SO4)2 crystallizes with the well-known NASICON-type structure. SAED and HRTEM experiments confirm the structural model, and no ordering between the PO4-3 and SO4-2 polyanions is detected. The electrochemical tests indicate that NaFe2(PO4)(SO4)2 is a 3 V sodium intercalating cathode. The electrical conductivity is relatively low (2.2 × 10-6 Scm-1 at 200 °C) and the obtained activation energy is ∼0.60eV. The GITT experiments indicate that the diffusivity values are in the range of 10-11-10-12 cm2/s within the measured sodium concentrations.

Synthesis of Graphene Oxide by Oxidation of Graphite with Ferrate(VI) Compounds: Myth or Reality?

PubMed

Sofer, Zdeněk; Luxa, Jan; Jankovský, Ondřej; Sedmidubský, David; Bystroň, Tomáš; Pumera, Martin

2016-09-19

It is well established that graphene oxide can be prepared by the oxidation of graphite using permanganate or chlorate in an acidic environment. Recently, however, the synthesis of graphene oxide using potassium ferrate(VI) ions has been reported. Herein, we critically replicate and evaluate this new ferrate(VI) oxidation method. In addition, we test the use of potassium ferrate(VI) for the synthesis of graphene oxide under various experimental routes. The synthesized materials are analyzed by a number of analytical methods in order to confirm or disprove the possibility of synthesizing graphene oxide by the ferrate(VI) oxidation route. Our results confirm the unsuitability of using ferrate(VI) for the oxidation of graphite on graphene oxide because of its high instability in an acidic environment and low oxidation power in neutral and alkaline environments. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pencil drawn strain gauges and chemiresistors on paper.

PubMed

Lin, Cheng-Wei; Zhao, Zhibo; Kim, Jaemyung; Huang, Jiaxing

2014-01-22

Pencil traces drawn on print papers are shown to function as strain gauges and chemiresistors. Regular graphite/clay pencils can leave traces composed of percolated networks of fine graphite powders, which exhibit reversible resistance changes upon compressive or tensile deflections. Flexible toy pencils can leave traces that are essentially thin films of graphite/polymer composites, which show reversible changes in resistance upon exposure to volatile organic compounds due to absorption/desorption induced swelling/recovery of the polymer binders. Pencil-on-paper devices are low-cost, extremely simple and rapid to fabricate. They are light, flexible, portable, disposable, and do not generate potentially negative environmental impact during processing and device fabrication. One can envision many other types of pencil drawn paper electronic devices that can take on a great variety of form factors. Hand drawn devices could be useful in resource-limited or emergency situations. They could also lead to new applications integrating art and electronics.

Glass Artworks

NASA Technical Reports Server (NTRS)

1988-01-01

Several NASA technologies have played part in growth and cost containment of studio glass art, among them a foam type insulation developed to meet a need for lightweight material that would reduce flame spread in aircraft fire. Foam comes in several forms and is widely used by glass artists, chiefly as an insulator for the various types of ovens used in glass working. Another Spinoff is alumina crucibles to contain molten glass. Before alumina crucibles were used, glass tanks were made of firebrick which tended to erode under high temperatures and cause impurities; this not only improved quality but made the process more cost effective. One more NASA technology that found its way into glass art working is a material known as graphite board, a special form of graphite originally developed for rocket motor applications. This graphite is used to exact compound angles and creates molds for poured glass artworks of dramatic design.

Unravelling the impact of reaction paths on mechanical degradation of intercalation cathodes for lithium-ion batteries

DOE PAGES

Li, Juchuan; Zhang, Qinglin; Xiao, Xingcheng; ...

2015-10-18

The intercalation compounds are generally considered as ideal electrode materials for lithium-ion batteries thanks to their minimum volume expansion and fast lithium ion diffusion. However, cracking still occurs in those compounds and has been identified as one of the critical issues responsible for their capacity decay and short cycle life, although the diffusion-induced stress and volume expansion are much smaller than those in alloying-type electrodes. Here, we designed a thin-film model system that enables us to tailor the cation ordering in LiNi 0.5Mn 1.5O 4 spinels and correlate the stress patterns, phase evolution, and cycle performances. Surprisingly, we found thatmore » distinct reaction paths cause negligible difference in the overall stress patterns but significantly different cracking behaviors and cycling performances: 95% capacity retention for disordered LiNi 0.5Mn 1.5O 4 and 48% capacity retention for ordered LiNi 0.5Mn 1.5O 4 after 2000 cycles. We were able to pinpoint that the extended solid-solution region with suppressed phase transformation attributed to the superior electrochemical performance of disordered spinel. Furthermore, this work envisions a strategy for rationally designing stable cathodes for lithium-ion batteries through engineering the atomic structure that extends the solid-solution region and suppresses phase transformation.« less

Orthorhombic fulleride (CH3NH2)K3C60 close to Mott-Hubbard instability: Ab initio study

NASA Astrophysics Data System (ADS)

Potočnik, Anton; Manini, Nicola; Komelj, Matej; Tosatti, Erio; Arčon, Denis

2012-08-01

We study the electronic structure and magnetic interactions in methylamine-intercalated orthorhombic alkali-doped fullerene (CH3NH2)K3C60 within the density functional theory. As in the simpler ammonia intercalated compound (NH3)K3C60, the orthorhombic crystal-field anisotropy Δ lifts the t1u triple degeneracy at the Γ point and drives the system deep into the Mott-insulating phase. However, the computed Δ and conduction electron bandwidth W cannot alone account for the abnormally low experimental Néel temperature, TN=11 K, of the methylamine compound, compared to the much higher value TN=40 K of the ammonia one. Significant interactions between CH3NH2 and C603- are responsible for the stabilization of particular fullerene-cage distortions and the ensuing low-spin S=1/2 state. These interactions also seem to affect the magnetic properties, as interfullerene exchange interactions depend on the relative orientation of deformations of neighboring C603- molecules. For the ferro-orientational order of CH3NH2-K+ groups we find an apparent reduced dimensionality in magnetic exchange interactions, which may explain the suppressed Néel temperature. The disorder in exchange interactions caused by orientational disorder of CH3NH2-K+ groups could further contribute to this suppression.

Tuning the electronic structure of graphene through alkali metal and halogen atom intercalation

NASA Astrophysics Data System (ADS)

Ahmad, Sohail; Miró, Pere; Audiffred, Martha; Heine, Thomas

2018-04-01

The deposition, intercalation and co-intercalation of heavy alkali metals and light halogens atoms in graphene mono- and bilayers have been studied using first principles density-functional calculations. Both the deposition and the intercalation of alkali metals gives rise to n-type doping due to the formation of M+-C- pairs. The co-intercalation of a 1:1 ratio of alkali metals and halogens derives into the formation of ionic pairs among the intercalated species, unaltering the electronic structure of the layered material.

Conditions affecting the formation of chlorinated carbon compounds during carbochlorination

NASA Astrophysics Data System (ADS)

Landsberg, A.; Wilson, R. D.; Burns, W.

1988-06-01

The Bureau of Mines, United States Department of the Interior, has conducted an extensive study of the relationship between various metal oxide carbochlorination reactions and carbon compound byproducts. Experiments in which oxides of titanium, zirconium, and aluminum with graphite, charcoal, metallurgical coke, and pctroleum coke were chlorinated at 600° to 1000 °C produced 136 identified and quantified carbon byproduct compounds. The 20 most abundant of these compounds were correlated with reactants and reaction conditions. Experimental results support a proposed carbochlorination reaction with an initial chlorine-carbon step followed by a reaction between the resulting chlorine-carbon products and the metal oxide.

Design, synthesis and biological evaluation of berberine-benzimidazole hybrids as new type of potentially DNA-targeting antimicrobial agents.

PubMed

Jeyakkumar, Ponmani; Zhang, Ling; Avula, Srinivasa Rao; Zhou, Cheng-He

2016-10-21

A series of novel berberine-benzimidazole derivatives were conveniently and efficiently synthesized and characterized by NMR, IR, MS and HRMS spectra. Most of the prepared compounds showed effective antimicrobial activities in contrast with clinical norfloxacin, chloromycin and fluconazole. Especially, compound 5d exhibited good anti-MRSA, anti-Escherichia coli, and anti-Salmonella typhi activity with low MIC values of 2-8 μg/mL, which were comparable or even superior to reference drugs. The preliminarily interactive investigation revealed that the most active compound 5d could effectively intercalate into DNA to form 5d-DNA complex and cleavage DNA by agarose gel electrophoresis experiments. It was also found that compound 5d was able to efficiently permeabilize the membranes of both Gram-positive (MRSA) and Gram-negative (E. coli DH52) bacteria. Experiments and molecular docking both showed that human serum albumin (HSA) could effectively transport compound 5d and hydrophobic interactions and hydrogen bonds play important roles in the association of compound 5d with HSA. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Bottom-up realization and electrical characterization of a graphene-based device.

PubMed

Maffucci, A; Micciulla, F; Cataldo, A; Miano, G; Bellucci, S

2016-03-04

We propose a bottom-up procedure to fabricate an easy-to-engineer graphene-based device, consisting of a microstrip-like circuit where few-layer graphene nanoplatelets are used to contact two copper electrodes. The graphene nanoplatelets are obtained by the microwave irradiation of intercalated graphite, i.e., an environmentally friendly, fast and low-cost procedure. The contact is created by a bottom-up process, driven by the application of a DC electrical field in the gap between the electrodes, yielding the formation of a graphene carpet. The electrical resistance of the device has been measured as a function of the gap length and device temperature. The possible use of this device as a gas sensor is demonstrated by measuring the sensitivity of its electrical resistance to the presence of gas. The measured results demonstrate a good degree of reproducibility in the fabrication process, and the competitive performance of devices, thus making the proposed technique potentially attractive for industrial applications.

Graphene oxide--MnO2 nanocomposites for supercapacitors.

PubMed

Chen, Sheng; Zhu, Junwu; Wu, Xiaodong; Han, Qiaofeng; Wang, Xin

2010-05-25

A composite of graphene oxide supported by needle-like MnO(2) nanocrystals (GO-MnO(2) nanocomposites) has been fabricated through a simple soft chemical route in a water-isopropyl alcohol system. The formation mechanism of these intriguing nanocomposites investigated by transmission electron microscopy and Raman and ultraviolet-visible absorption spectroscopy is proposed as intercalation and adsorption of manganese ions onto the GO sheets, followed by the nucleation and growth of the crystal species in a double solvent system via dissolution-crystallization and oriented attachment mechanisms, which in turn results in the exfoliation of GO sheets. Interestingly, it was found that the electrochemical performance of as-prepared nanocomposites could be enhanced by the chemical interaction between GO and MnO(2). This method provides a facile and straightforward approach to deposit MnO(2) nanoparticles onto the graphene oxide sheets (single layer of graphite oxide) and may be readily extended to the preparation of other classes of hybrids based on GO sheets for technological applications.

Creation of nanosized holes in graphene planes for improvement of rate capability of lithium-ion batteries

NASA Astrophysics Data System (ADS)

Bulusheva, L. G.; Stolyarova, S. G.; Chuvilin, A. L.; Shubin, Yu V.; Asanov, I. P.; Sorokin, A. M.; Mel'gunov, M. S.; Zhang, Su; Dong, Yue; Chen, Xiaohong; Song, Huaihe; Okotrub, A. V.

2018-04-01

Holes with an average size of 2-5 nm have been created in graphene layers by heating of graphite oxide (GO) in concentrated sulfuric acid followed by annealing in an argon flow. The hot mineral acid acts simultaneously as a defunctionalizing and etching agent, removing a part of oxygen-containing groups and lattice carbon atoms from the layers. Annealing of the holey reduced GO at 800 °C-1000 °C causes a decrease of the content of residual oxygen and the interlayer spacing thus producing thin compact stacks from holey graphene layers. Electrochemical tests of the obtained materials in half-cells showed that the removal of oxygen and creation of basal holes lowers the capacity loss in the first cycle and facilitates intercalation-deintercalation of lithium ions. This was attributed to minimization of electrolyte decomposition reactions, easier desolvation of lithium ions near the hole boundaries and appearance of multiple entrances for the naked ions into graphene stacks.

Ultrafast lithium diffusion in bilayer graphene

NASA Astrophysics Data System (ADS)

Kühne, Matthias; Paolucci, Federico; Popovic, Jelena; Ostrovsky, Pavel M.; Maier, Joachim; Smet, Jurgen H.

2017-09-01

Solids that simultaneously conduct electrons and ions are key elements for the mass transfer and storage required in battery electrodes. Single-phase materials with a high electronic and high ionic conductivity at room temperature are hard to come by, and therefore multiphase systems with separate ion and electron channels have been put forward instead. Here we report on bilayer graphene as a single-phase mixed conductor that demonstrates Li diffusion faster than in graphite and even surpassing the diffusion of sodium chloride in liquid water. To measure Li diffusion, we have developed an on-chip electrochemical cell architecture in which the redox reaction that forces Li intercalation is localized only at a protrusion of the device so that the graphene bilayer remains unperturbed from the electrolyte during operation. We performed time-dependent Hall measurements across spatially displaced Hall probes to monitor the in-plane Li diffusion kinetics within the graphene bilayer and measured a diffusion coefficient as high as 7 × 10-5 cm2 s-1.

Hydrothermal synthesis and characterization of vanadyl phosphate based cathode materials for lithium ion batteries

NASA Astrophysics Data System (ADS)

Chung, Youngmin

Transition metal phosphate materials have been researched as candidates for lithium-ion battery cathodes for about two decades. Among them, vanadium phosphate compounds are attractive due to their higher free energy of reaction than the corresponding iron compounds, and the greater possible change of oxidation state from V5+ to V3+. This thesis work firstly focuses on the chemical and electrochemical lithiation of epsilon--VOPO4 investigating the possibility of multi-electron intercalation. The second focus is on hydrothermal synthesis and characterization of epsilon--LiVOPO4. The hydrothermal synthesis method developed in this work produces pure epsilon-LiVOPO 4 at high temperature hydrothermal reaction and pure LiVOPO4˙2H 2O at low temperature. The first charge capacity of hydrothermal epsilon-LiVOPO 4 is around 308 mAh/g, which is almost 97% of the theoretical capacity. It also shows good reversibility in the first five cycles after which capacity fading occurs. For more detailed structural analysis of hydrothermal epsilon-LiVOPO 4, we used in-situ synchrotron XRD and EXAFS upon heating combined with TGA-MS. These techniques have revealed intercalated protons that are removed at about 350 °C, and a reversible symmetry change from triclinic to monoclinic at high temperature. Furthermore, we have used chemical lithiation with BuLi to produce and characterize epsilon-Li2VOPO 4 phase. Finally, we have modified the hydrothermal method to produce Cr-substituted epsilon--LiVOPO4 by changing the amount LiOH and adding Cr precursor. Cr substitution is found to modify the stoichiometry of the compound and to improve its cyclability at both high and low current densities.

Layered materials

NASA Astrophysics Data System (ADS)

Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

2014-06-01

Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and an overview of current areas of research interest.

Characterization of PMR polyimide resin and prepreg

NASA Technical Reports Server (NTRS)

Lindenmeyer, P. H.; Sheppard, C. H.

1984-01-01

Procedures for the chemical characterization of PMR-15 resin solutions and graphite-reinforced prepregs were developed, and a chemical data base was established. In addition, a basic understanding of PMR-15 resin chemistry was gained; this was translated into effective processing procedures for the production of high quality graphite composites. During the program the PMR monomers and selected model compounds representative of postulated PMR-15 solution chemistry were acquired and characterized. Based on these data, a baseline PMR-15 resin was formulated and evaluated for processing characteristics and composite properties. Commercially available PMR-15 resins were then obtained and chemically characterized. Composite panels were fabricated and evaluated.

Rapid prototyping of carbon-based chemiresistive gas sensors on paper

PubMed Central

Mirica, Katherine A.; Azzarelli, Joseph M.; Weis, Jonathan G.; Schnorr, Jan M.; Swager, Timothy M.

2013-01-01

Chemically functionalized carbon nanotubes (CNTs) are promising materials for sensing of gases and volatile organic compounds. However, the poor solubility of carbon nanotubes hinders their chemical functionalization and the subsequent integration of these materials into devices. This manuscript describes a solvent-free procedure for rapid prototyping of selective chemiresistors from CNTs and graphite on the surface of paper. This procedure enables fabrication of functional gas sensors from commercially available starting materials in less than 15 min. The first step of this procedure involves the generation of solid composites of CNTs or graphite with small molecule selectors—designed to interact with specific classes of gaseous analytes—by solvent-free mechanical mixing in a ball mill and subsequent compression. The second step involves deposition of chemiresistive sensors by mechanical abrasion of these solid composites onto the surface of paper. Parallel fabrication of multiple chemiresistors from diverse composites rapidly generates cross-reactive arrays capable of sensing and differentiating gases and volatile organic compounds at part-per-million and part-per-thousand concentrations. PMID:23942132

Porous Graphitic Carbon Liquid Chromatography-Mass Spectrometry Analysis of Drought Stress-Responsive Raffinose Family Oligosaccharides in Plant Tissues.

PubMed

Jorge, Tiago F; Florêncio, Maria H; António, Carla

2017-01-01

Drought is a major limiting factor in agriculture and responsible for dramatic crop yield losses worldwide. The adjustment of the metabolic status via accumulation of drought stress-responsive osmolytes is one of the many strategies that some plants have developed to cope with water deficit conditions. Osmolytes are highly polar compounds, analysis of whcih is difficult with typical reversed-phase chromatography. Porous graphitic carbon (PGC) has shown to be a suitable alternative to reversed-phase stationary phases for the analysis of highly polar compounds typically found in the plant metabolome. In this chapter, we describe the development and validation of a PGC-based liquid chromatography tandem mass spectrometry (LC-MS n ) method suitable for the target analysis of water-soluble carbohydrates, such as raffinose family oligosaccharides (RFOs). We present detailed information regarding PGC column equilibration, LC-MS n system operation, data analysis, and important notes to be considered during the steps of method development and validation.

Dissecting the Dynamic Pathways of Stereoselective DNA Threading Intercalation

PubMed Central

Almaqwashi, Ali A.; Andersson, Johanna; Lincoln, Per; Rouzina, Ioulia; Westerlund, Fredrik; Williams, Mark C.

2016-01-01

DNA intercalators that have high affinity and slow kinetics are developed for potential DNA-targeted therapeutics. Although many natural intercalators contain multiple chiral subunits, only intercalators with a single chiral unit have been quantitatively probed. Dumbbell-shaped DNA threading intercalators represent the next order of structural complexity relative to simple intercalators, and can provide significant insights into the stereoselectivity of DNA-ligand intercalation. We investigated DNA threading intercalation by binuclear ruthenium complex [μ-dppzip(phen)4Ru2]4+ (Piz). Four Piz stereoisomers are defined by the chirality of the intercalating subunit (Ru(phen)2dppz) and the distal subunit (Ru(phen)2ip), respectively, each of which can be either right-handed (Δ) or left-handed (Λ). We used optical tweezers to measure single DNA molecule elongation due to threading intercalation, revealing force-dependent DNA intercalation rates and equilibrium dissociation constants. The force spectroscopy analysis provided the zero-force DNA binding affinity, the equilibrium DNA-ligand elongation Δxeq, and the dynamic DNA structural deformations during ligand association xon and dissociation xoff. We found that Piz stereoisomers exhibit over 20-fold differences in DNA binding affinity, from a Kd of 27 ± 3 nM for (Δ,Λ)-Piz to a Kd of 622 ± 55 nM for (Λ,Δ)-Piz. The striking affinity decrease is correlated with increasing Δxeq from 0.30 ± 0.02 to 0.48 ± 0.02 nm and xon from 0.25 ± 0.01 to 0.46 ± 0.02 nm, but limited xoff changes. Notably, the affinity and threading kinetics is 10-fold enhanced for right-handed intercalating subunits, and 2- to 5-fold enhanced for left-handed distal subunits. These findings demonstrate sterically dispersed transition pathways and robust DNA structural recognition of chiral intercalators, which are critical for optimizing DNA binding affinity and kinetics. PMID:27028636

Is it intelligent to intercalate? A two centre cross-sectional study exploring the value of intercalated degrees, and the possible effects of the recent tuition fee rise in England.

PubMed

Stubbs, Timothy Alan; Lightman, Elewys G; Mathieson, Peter

2013-01-24

To explore the value of intercalated degrees, including student perceptions and academic sequelae. To gauge the likely effect of the recent tuition fee rise and to identify any differences in intercalated degrees between Bristol and Sheffield universities. Cross-sectional study using questionnaires. Bristol and Sheffield Medical Schools, UK. 1484 medical students in their clinical years were e-mailed the questionnaire. 578 students responded: 291 from Bristol and 287 from Sheffield (n=578; mean age=22.41; SD 1.944; 38.9% male; 61.1% female). The response rate from previous intercalators was 52.5% from Bristol and 58.7% from Sheffield, while for non-intercalators it was 27.7% and 34.6%, respectively. (1) Student preconceptions, opinions, results and academic sequelae from intercalated degrees at both centres. (2) Students' attitudes concerning the effect of the increase in tuition fees. Those with clinical academic supervisors gained significantly more posters (p=0.0002) and publications (p<0.0001), and also showed a trend to gain more first class honours (p=0.055). Students at Sheffield had a significantly greater proportion of clinical academic supervisors than students at Bristol (p<0.0001). 89.2% said that an intercalated degree was the right decision for them; however, only 27.4% stated they would have intercalated if fees had been £9000 per annum. Students clearly value intercalated degrees, feel they gained a substantial advantage over their peers as well as skills helpful for their future careers. The rise in tuition fees is likely to reduce the number of medical students opting to undertake an intercalated degree, and could result in a further reduction in numbers following an academic path. Sheffield University have more intercalating students supervised by clinical academics. Clinical academics appear more effective as supervisors for medical students undertaking an intercalated degree in terms of results and additional academic sequelae.

Adjusting the thermoelectric properties of copper(I) oxide-graphite-polymer pastes and the applications of such flexible composites.

PubMed

Andrei, Virgil; Bethke, Kevin; Rademann, Klaus

2016-04-28

We present a facile alternative to other well known strategies for synthesizing flexible thermoelectric materials. Instead of printing thin active layers on flexible substrates or doping conductive polymers, we produce thermoelectric pastes, using a mixture of graphite, copper(I) oxide and polychlorotrifluoroethene. The Seebeck coefficient of the investigated pastes varies between 10 and 600 μV K(-1), while the electrical conductivity spans over an even wider range of 10(-4) to 10(2) S m(-1). Here, the influence of phenomena such as percolation on the electrical transport is revealed. The resulting power factor reaches 5.69 × 10(-4) ± 0.70 × 10(-4) μW m(-1) K(-2) for the graphite-polymer paste, with an unexpected minimum at a graphite molar fraction of approximately 0.4. The values are comparable to those of the powder mixtures, which are slightly higher, but less precisely tunable. Such compounds are further evaluated for practical applications. The graphite-polymer paste is used to exemplify, how a flexible thermoelectric sensor can be easily manufactured, step by step. Our results represent a proof of principle, that thermoelectric pastes are viable alternatives to current solutions. A further expansion of the scope for the composites can be achieved by using high performance thermoelectric materials and conductive polymers.

ZnO/graphite composites and its antibacterial activity at different conditions.

PubMed

Dědková, Kateřina; Janíková, Barbora; Matějová, Kateřina; Čabanová, Kristina; Váňa, Rostislav; Kalup, Aleš; Hundáková, Marianna; Kukutschová, Jana

2015-10-01

The paper reports laboratory preparation, characterization and in vitro evaluation of antibacterial activity of ZnO/graphite nanocomposites. Zinc chloride and sodium carbonate served as precursors for synthesis of zinc oxide, while micromilled and natural graphite were used as the matrix for ZnO nanoparticles anchoring. During the reaction of ZnCl2 with saturated aqueous solution of Na2CO3a new compound is created. During the calcination at the temperature of 500 °C this new precursors decomposes and ZnO nanoparticles are formed. Composites ZnO/graphite with 50 wt.% of ZnO particles were prepared. X-ray powder diffraction and Raman microspectroscopy served as phase-analytical methods. Scanning electron microscopy technique was used for morphology characterization of the prepared samples and EDS mapping for visualization of elemental distribution. A developed modification of the standard microdilution test was used for in vitro evaluation of daylight induced antibacterial activity and antibacterial activity at dark conditions. Common human pathogens served as microorganism for antibacterial assay. Antibacterial activity of ZnO/graphite composites could be based on photocatalytic reaction; however there is a role of Zn(2+) ions on the resulting antibacterial activity which proved the experiments in dark condition. There is synergistic effect between Zn(2+) caused and reactive oxygen species caused antibacterial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Barrier Properties of Layered-Silicate Reinforced Ethylenepropylenediene Monomer/Chloroprene Rubber Nanorubbers.

PubMed

Wu, Chang Mou; Hsieh, Wen Yen; Cheng, Kuo Bin; Lai, Chiu-Chun; Lee, Kuei Chi

2018-05-09

The triacetin and nitroglycerin barrier properties of layered-silicate reinforced ethylenepropylenediene monomer/chloroprene rubber (EPDM/CR) nanorubbers were investigated as rocket-propellant inhibitors. EPDM/CR nanorubbers with intercalated structures were formulated and prepared by the melt-compounding method. The triacetin permeability and nitroglycerin absorption were observed to decrease with increasing layered-silicate content. The layered silicates also improved the flame retardancies of the nanorubbers by forming silicate reinforced carbonaceous chars. Layered-silicate reinforced EPDM/CR nanorubbers are potentially effective rocket propellant-inhibiting materials.

Resolving DNA-ligand intercalation in the entropic stretching regime

NASA Astrophysics Data System (ADS)

Almaqwashi, Ali A.

Single molecule studies of DNA intercalation are typically conducted by applying stretching forces to obtain force-dependent DNA elongation measurements. The zero-force properties of DNA intercalation are determined by equilibrium and kinetic force-analysis. However, the applied stretching forces that are above the entropic regime (>5 pN) prevent DNA-DNA contact which may eliminate competitive DNA-ligand interactions. In particular, it is noted that cationic mono-intercalators investigated by single molecule force spectroscopy are mostly found to intercalate DNA with single rate, while bulk studies reported additional slower rates. Here, a proposed framework quantifies DNA intercalation by cationic ligands in competition with relatively rapid kinetic DNA-ligand aggregation. At a constant applied force in the entropic stretching regime, the analysis illustrates that DNA intercalation would be measurably optimized only within a narrow range of low ligand concentrations. As DNA intercalators are considered for potential DNA-targeted therapeutics, this analysis provides insights in tuning ligand concertation to maximize therapeutics efficiency.

Composite TiO2/clays materials for photocatalytic NOx oxidation

NASA Astrophysics Data System (ADS)

Todorova, N.; Giannakopoulou, T.; Karapati, S.; Petridis, D.; Vaimakis, T.; Trapalis, C.

2014-11-01

TiO2 photocatalyst received much attention for air purification applications especially for removal of air pollutants like NOx, VOCs etc. It has been established that the activity of the photocatalyst can be significantly enhanced by its immobilization onto suitable substrates like inorganic minerals, porous silica, hydroxyapatite, adsorbent materials like activated carbon, various co-catalysts such as semiconductors, graphene, reduced graphite oxide, etc. In the present work, photocatalytic composite materials consisted of mineral substrate and TiO2 in weight ratio 1:1 were manufactured and examined for oxidation and removal of nitric oxides NOx (NO and NO2). Commercial titania P25 (Evonik-Degussa) and urea-modified P25 were used as photocatalytically active components. Inorganic minerals, namely kunipia, talk and hydrotalcite were selected as supporting materials due to their layered structure and expected high NOx adsorption capability. Al3+ and Ca2+ intercalation was applied in order to improve the dispersion of TiO2 and its loading into the supporting matrix. The X-ray diffraction analysis and Scanning Electron Microscopy revealed the binary structure of the composites and homogeneous dispersion of the photocatalyst into the substrates. The photocatalytic behavior of the materials in NOx oxidation and removal was investigated under UV and visible light irradiation. The composite materials exhibited superior photocatalytic activity than the bare titania under both types of irradiation. Significant visible light activity was recorded for the composites containing urea-modified titania that was accredited to the N-doping of the semiconductor. Among the different substrates, the hydrotalcite caused highest increase in the NOx removal, while among the intercalation ions the Ca2+ was more efficient. The results were related to the improved dispersion of the TiO2 and the synergetic activity of the substrates as NOx adsorbers.

Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

NASA Astrophysics Data System (ADS)

Schindler, Matthias; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

2016-05-01

Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO2 and reduced to graphite to determine 14C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

Onset of superconductivity in sodium and potassium intercalated molybdenum disulphide

NASA Technical Reports Server (NTRS)

Somoano, R. B.; Rembaum, A.

1971-01-01

Molybdenum disulfide in the form of natural crystals or powder has been intercalated at -65 to -70 C with sodium and potassium using the liquid ammonia technique. All intercalated samples were found to show a superconducting transition. A plot of the percent of diamagnetic throw versus temperature indicates the possible existence of two phases in the potassium intercalated molybdenum disulfide. The onset of superconductivity in potassium and sodium intercalated molybdenite powder was found to be approximately 6.2 and approximately 4.5 K, respectively. The observed superconductivity is believed to be due to an increase in electron density as a result of intercalation.

Solution structure and thermodynamics of 2',5' RNA intercalation.

PubMed

Horowitz, Eric D; Lilavivat, Seth; Holladay, Benjamin W; Germann, Markus W; Hud, Nicholas V

2009-04-29

As a means to explore the influence of the nucleic acid backbone on the intercalative binding of ligands to DNA and RNA, we have determined the solution structure of a proflavine-bound 2',5'-linked octamer duplex with the sequence GCCGCGGC. This structure represents the first NMR structure of an intercalated RNA duplex, of either backbone structural isomer. By comparison with X-ray crystal structures, we have identified similarities and differences between intercalated 3',5' and 2',5'-linked RNA duplexes. First, the two forms of RNA have different sugar pucker geometries at the intercalated nucleotide steps, yet have the same interphosphate distances. Second, as in intercalated 3',5' RNA, the phosphate backbone angle zeta at the 2',5' RNA intercalation site prefers to be in the trans conformation, whereas unintercalated 2',5' and 3',5' RNA prefer the -gauche conformation. These observations provide new insights regarding the transitions required for intercalation of a phosphodiester-ribose backbone and suggest a possible contribution of the backbone to the origin of the nearest-neighbor exclusion principle. Thermodynamic studies presented for intercalation of both structural RNA isomers also reveal a surprising sensitivity of intercalator binding enthalpy and entropy to the details of RNA backbone structure.

Highly Conductive and Transparent Large-Area Bilayer Graphene Realized by MoCl5 Intercalation.

PubMed

Kinoshita, Hiroki; Jeon, Il; Maruyama, Mina; Kawahara, Kenji; Terao, Yuri; Ding, Dong; Matsumoto, Rika; Matsuo, Yutaka; Okada, Susumu; Ago, Hiroki

2017-11-01

Bilayer graphene (BLG) comprises a 2D nanospace sandwiched by two parallel graphene sheets that can be used to intercalate molecules or ions for attaining novel functionalities. However, intercalation is mostly demonstrated with small, exfoliated graphene flakes. This study demonstrates intercalation of molybdenum chloride (MoCl 5 ) into a large-area, uniform BLG sheet, which is grown by chemical vapor deposition (CVD). This study reveals that the degree of MoCl 5 intercalation strongly depends on the stacking order of the graphene; twist-stacked graphene shows a much higher degree of intercalation than AB-stacked. Density functional theory calculations suggest that weak interlayer coupling in the twist-stacked graphene contributes to the effective intercalation. By selectively synthesizing twist-rich BLG films through control of the CVD conditions, low sheet resistance (83 Ω ▫ -1 ) is realized after MoCl 5 intercalation, while maintaining high optical transmittance (≈95%). The low sheet resistance state is relatively stable in air for more than three months. Furthermore, the intercalated BLG film is applied to organic solar cells, realizing a high power conversion efficiency. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design, synthesis and biological evaluation of 5-fluorouracil-derived benzimidazoles as novel type of potential antimicrobial agents.

PubMed

Fang, Xue-Jie; Jeyakkumar, Ponmani; Avula, Srinivasa Rao; Zhou, Qian; Zhou, Cheng-He

2016-06-01

A series of 5-fluorouracil benzimidazoles as novel type of potential antimicrobial agents were designed and synthesized for the first time. Bioactive assay manifested that some of the prepared compounds exhibited good or even stronger antibacterial and antifungal activities against the tested strains in comparison with reference drugs norfloxacin, chloromycin and fluconazole. Noticeably, 3-fluorobenzyl benzimidazole derivative 5c gave remarkable antimicrobial activities against Saccharomyces cerevisiae, MRSA and Bacillus proteus with MIC values of 1, 2 and 4μg/mL, respectively. Experimental research revealed that compound 5c could effectively intercalate into calf thymus DNA to form compound 5c-DNA complex which might block DNA replication and thus exert antimicrobial activities. Molecular docking indicated that compound 5c should bind with DNA topoisomerase IA through three hydrogen bonds by the use of fluorine atom and oxygen atoms in 5-fluorouracil with the residue Lys 423. Copyright © 2016 Elsevier Ltd. All rights reserved.

Behavior of graphite under heat load and in contact with a hydrogen plasma

NASA Astrophysics Data System (ADS)

Bohdansky, J.; Croessmann, C. D.; Linke, J.; McDonald, J. M.; Morse, D. H.; Pontau, A. E.; Watson, R. D.; Whitley, J. B.; Goebel, D. M.; Hirooka, Y.; Leung, K.; Conn, R. W.; Roth, J.; Ottenberger, W.; Kotzlowski, H. E.

1987-05-01

Graphite is extensively used in large tokamaks today. In these machines the material is exposed to vacuum, to intense heat loads, and to the edge plasma. The use of graphite in such machines, therefore, depends on the outgassing behavior, the heat shock resistance, and thermochemical properties in a hydrogen plasma. Investigations of these properties made at different laboratories are described here. Experiments conducted at Sandia National Laboratories (SNL), Livermore, and the Max-Planck-Institut für Plasmaphysik (IPP) in Garching showed that the outgassing behavior of fine-grain reactor-grade graphite and carbon fiber composites depends on the pretreatment (manufacturing and/or storage). However, after proper outgassing the samples tested behave similarly in the case of fine-grain graphite, but the outgassing remains high for the carbon fiber composites. Heat shock tests have been made with the Electron Beam Test System (EBTS) at SNL, Albuquerque. Directly cooled graphite samples (FE 159 graphite brazed onto Mo tubes) showed no failure at a heat load of 700 W/cm 2, 20 s; or 10 kW, 1 s. Thermal erosion due to sublimination and particle emission from the graphite surface was observed. This effect is related to the surface temperature and becomes significant at temperatures above 2500°K. Fourteen different types of graphite were tested; the main differences among these samples were the different surface temperatures obtained under the same heating conditions. Cracking due to heat shocks was observed in some of the samples, but none of the carbon fiber composites failed. Thermochemical properties have been tested in the PISCES plasma generator at UCLA for ion energies of around 100 eV. The formation of C-H compounds was observed spectroscopically at sample temperatures of around 600°C. However, this chemical reaction did not lead to erosion as observed in beam experiments but to a drastic change of the surface structure due to redeposition. Carbon-hydrogen lines were still observed at sample temperatures of around 100°C. Under these conditions the erosion yield is high and in agreement with those measured in beam experiments.

Intercalation and de-intercalation pathway of proflavine through the minor and major grooves of DNA: roles of water and entropy.

PubMed

Sasikala, Wilbee D; Mukherjee, Arnab

2013-05-07

DNA intercalation is a clinically relevant biophysical process due to its potential to inhibit the growth and survival of tumor cells and microbes through the arrest of the transcription and replication processes. Extensive kinetic and thermodynamic studies have followed since the discovery of the intercalative binding mode. However, the molecular mechanism and the origin of the thermodynamic and kinetic profile of the process are still not clear. Here we have constructed the free energy landscape of intercalation, de-intercalation and dissociation from both the major and minor grooves of DNA using extensive all-atom metadynamics simulations, capturing both the free energy barriers and stability in close agreement with fluorescence kinetic experiments. In the intercalated state, an alternate orientation of proflavine is found with an almost equal stability compared to the crystal orientation, however, separated by a 5.0 kcal mol(-1) barrier that decreases as the drug approaches the groove edges. This study provides a comprehensive picture in comparison with experiments, which indicates that the intercalation and de-intercalation of proflavine happen through the major groove side, although the effective intercalation barrier increases because the path of intercalation goes through the stable (abortive) minor groove bound state, making the process a millisecond long one in excellent agreement with the experiments. The molecular origin of the higher barrier for the intercalation from the minor groove side is attributed to the desolvation energy of DNA and the loss of entropy, while the barrier from the major groove, in the absence of desolvation energy, is primarily entropic.

Reshaping the Energy Landscape Transforms the Mechanism and Binding Kinetics of DNA Threading Intercalation.

PubMed

Clark, Andrew G; Naufer, M Nabuan; Westerlund, Fredrik; Lincoln, Per; Rouzina, Ioulia; Paramanathan, Thayaparan; Williams, Mark C

2018-02-06

Molecules that bind DNA via threading intercalation show high binding affinity as well as slow dissociation kinetics, properties ideal for the development of anticancer drugs. To this end, it is critical to identify the specific molecular characteristics of threading intercalators that result in optimal DNA interactions. Using single-molecule techniques, we quantify the binding of a small metal-organic ruthenium threading intercalator (Δ,Δ-B) and compare its binding characteristics to a similar molecule with significantly larger threading moieties (Δ,Δ-P). The binding affinities of the two molecules are the same, while comparison of the binding kinetics reveals significantly faster kinetics for Δ,Δ-B. However, the kinetics is still much slower than that observed for conventional intercalators. Comparison of the two threading intercalators shows that the binding affinity is modulated independently by the intercalating section and the binding kinetics is modulated by the threading moiety. In order to thread DNA, Δ,Δ-P requires a "lock mechanism", in which a large length increase of the DNA duplex is required for both association and dissociation. In contrast, measurements of the force-dependent binding kinetics show that Δ,Δ-B requires a large DNA length increase for association but no length increase for dissociation from DNA. This contrasts strongly with conventional intercalators, for which almost no DNA length change is required for association but a large DNA length change must occur for dissociation. This result illustrates the fundamentally different mechanism of threading intercalation compared with conventional intercalation and will pave the way for the rational design of therapeutic drugs based on DNA threading intercalation.

RETENTION OF HALOCARBONS ON A HEXAFLUOROPROPYLENE EPOXIDE-MODIFIED GRAPHITIZED CARBON BLACK - IV. PROPANE- BASED COMPOUNDS

EPA Science Inventory

The retention characteristics of 25 propane-based bromofluorocarbon, chlorocarbon, chlorofluorocarbon, and fluorocarbon fluids have been studied as a function of temperature on a stationary phase consisting of a 5% (m/m) coating of a low-molecular-mass polymer of hexafluoropropyl...

Anticancer effect and structure-activity analysis of marine products isolated from metabolites of mangrove fungi in the South China Sea.

PubMed

Tao, Li-yang; Zhang, Jian-ye; Liang, Yong-ju; Chen, Li-ming; Zhen, Li-sheng; Wang, Fang; Mi, Yan-jun; She, Zhi-gang; To, Kenneth Kin Wah; Lin, Yong-cheng; Fu, Li-wu

2010-04-01

Marine-derived fungi provide plenty of structurally unique and biologically active secondary metabolites. We screened 87 marine products from mangrove fungi in the South China Sea for anticancer activity by MTT assay. 14% of the compounds (11/86) exhibited a potent activity against cancer in vitro. Importantly, some compounds such as compounds 78 and 81 appeared to be promising for treating cancer patients with multidrug resistance, which should encourage more efforts to isolate promising candidates for further development as clinically useful chemotherapeutic drugs. Furthermore, DNA intercalation was not involved in their anticancer activities, as determined by DNA binding assay. On the other hand, the structure-activity analysis indicated that the hydroxyl group was important for their cytotoxic activity and that bulky functional groups such as phenyl rings could result in a loss of biological activity, which will direct the further development of marine product-based derivatives.

Improvement of the Heat Resistance of Prussian Blue Nanoparticles in a Clay Film Composed of Smectite Clay and ε-Caprolactam.

PubMed

Ono, Kenta; Nakamura, Takashi; Ebina, Takeo; Ishizaki, Manabu; Kurihara, Masato

2018-06-04

Prussian blue (PB) is limited in its application by its breakdown at elevated temperatures. To improve the heat resistance of PB, we prepared a composite film comprising PB nanoparticles (NPs), smectite clay, and an organic compound. The composite film had a microstructure in which PB NPs were intercalated between smectite/organic compound layers. The predominant oxidation temperature of the PB NPs in the composite film was around 500 °C in air, higher than the oxidation temperature of bulk PB in air (250 °C). This improvement in the oxidation temperature may be due to the composite film acting as a barrier to oxygen gas. These results indicate the effectiveness of clay materials for the improvement of heat resistance for low-temperature decomposition compounds, not only PB but also other porous coordination polymers.

Carbon nanosheet frameworks derived from peat moss as high performance sodium ion battery anodes.

PubMed

Ding, Jia; Wang, Huanlei; Li, Zhi; Kohandehghan, Alireza; Cui, Kai; Xu, Zhanwei; Zahiri, Beniamin; Tan, Xuehai; Lotfabad, Elmira Memarzadeh; Olsen, Brian C; Mitlin, David

2013-12-23

We demonstrate that peat moss, a wild plant that covers 3% of the earth's surface, serves as an ideal precursor to create sodium ion battery (NIB) anodes with some of the most attractive electrochemical properties ever reported for carbonaceous materials. By inheriting the unique cellular structure of peat moss leaves, the resultant materials are composed of three-dimensional macroporous interconnected networks of carbon nanosheets (as thin as 60 nm). The peat moss tissue is highly cross-linked, being rich in lignin and hemicellulose, suppressing the nucleation of equilibrium graphite even at 1100 °C. Rather, the carbons form highly ordered pseudographitic arrays with substantially larger intergraphene spacing (0.388 nm) than graphite (c/2 = 0.3354 nm). XRD analysis demonstrates that this allows for significant Na intercalation to occur even below 0.2 V vs Na/Na(+). By also incorporating a mild (300 °C) air activation step, we introduce hierarchical micro- and mesoporosity that tremendously improves the high rate performance through facile electrolyte access and further reduced Na ion diffusion distances. The optimized structures (carbonization at 1100 °C + activation) result in a stable cycling capacity of 298 mAh g(-1) (after 10 cycles, 50 mA g(-1)), with ∼150 mAh g(-1) of charge accumulating between 0.1 and 0.001 V with negligible voltage hysteresis in that region, nearly 100% cycling Coulombic efficiency, and superb cycling retention and high rate capacity (255 mAh g(-1) at the 210th cycle, stable capacity of 203 mAh g(-1) at 500 mA g(-1)).

Effectiveness of Co intercalation between Graphene and Ir(1 1 1)

NASA Astrophysics Data System (ADS)

Carlomagno, I.; Drnec, J.; Scaparro, A. M.; Cicia, S.; Mobilio, S.; Felici, R.; Meneghini, C.

2018-04-01

Graphene can be used to avoid the oxidation of metallic films. This work explores the effectiveness of such stabilizing effect on Cobalt (Co) films intercalated between Graphene and Ir(1 1 1). After intercalation at 300 °C, two Co films are exposed to ambient pressure and investigated using Co-K edge X-ray Absorption Near Edge Spectroscopy. The formation of a disordered oxide phase is observed, and associated to the presence of some non-intercalated Co. Further annealing at 500 °C causes the oxide reduction to metallic Co which further intercalates below the Graphene. Once the intercalation is completed, Graphene prevents the Co from oxidation under ambient pressure conditions.

Double-chamber electrode for spectrochemical determination of chlorine and other halogens

USGS Publications Warehouse

de Paiva, Azevedo; Specht, A.W.; Harner, R.S.

1954-01-01

A double-chamber, graphite electrode, suitable for d.c. arc determination of halogens by means of the alkaline earth halide bands, is described. An upper chamber holds the alkaline earth compound and an interconnected, lower chamber holds the halogen compound. This arrangement assures that there will be an abundance of alkaline earths in the arc by the time the halogen is volatilized from the lower chamber, and thereby promotes maximum emission of the alkaline earth halide bands. ?? 1954.

Mechanisms of small molecule–DNA interactions probed by single-molecule force spectroscopy

PubMed Central

Almaqwashi, Ali A.; Paramanathan, Thayaparan; Rouzina, Ioulia; Williams, Mark C.

2016-01-01

There is a wide range of applications for non-covalent DNA binding ligands, and optimization of such interactions requires detailed understanding of the binding mechanisms. One important class of these ligands is that of intercalators, which bind DNA by inserting aromatic moieties between adjacent DNA base pairs. Characterizing the dynamic and equilibrium aspects of DNA-intercalator complex assembly may allow optimization of DNA binding for specific functions. Single-molecule force spectroscopy studies have recently revealed new details about the molecular mechanisms governing DNA intercalation. These studies can provide the binding kinetics and affinity as well as determining the magnitude of the double helix structural deformations during the dynamic assembly of DNA–ligand complexes. These results may in turn guide the rational design of intercalators synthesized for DNA-targeted drugs, optical probes, or integrated biological self-assembly processes. Herein, we survey the progress in experimental methods as well as the corresponding analysis framework for understanding single molecule DNA binding mechanisms. We discuss briefly minor and major groove binding ligands, and then focus on intercalators, which have been probed extensively with these methods. Conventional mono-intercalators and bis-intercalators are discussed, followed by unconventional DNA intercalation. We then consider the prospects for using these methods in optimizing conventional and unconventional DNA-intercalating small molecules. PMID:27085806

Is it intelligent to intercalate? A two centre cross-sectional study exploring the value of intercalated degrees, and the possible effects of the recent tuition fee rise in England

PubMed Central

Stubbs, Timothy Alan; Lightman, Elewys G; Mathieson, Peter

2013-01-01

Aims and objectives To explore the value of intercalated degrees, including student perceptions and academic sequelae. To gauge the likely effect of the recent tuition fee rise and to identify any differences in intercalated degrees between Bristol and Sheffield universities. Design Cross-sectional study using questionnaires. Setting Bristol and Sheffield Medical Schools, UK. Participants 1484 medical students in their clinical years were e-mailed the questionnaire. 578 students responded: 291 from Bristol and 287 from Sheffield (n=578; mean age=22.41; SD 1.944; 38.9% male; 61.1% female). The response rate from previous intercalators was 52.5% from Bristol and 58.7% from Sheffield, while for non-intercalators it was 27.7% and 34.6%, respectively. Main outcome measures (1) Student preconceptions, opinions, results and academic sequelae from intercalated degrees at both centres. (2) Students’ attitudes concerning the effect of the increase in tuition fees. Results Those with clinical academic supervisors gained significantly more posters (p=0.0002) and publications (p<0.0001), and also showed a trend to gain more first class honours (p=0.055). Students at Sheffield had a significantly greater proportion of clinical academic supervisors than students at Bristol (p<0.0001). 89.2% said that an intercalated degree was the right decision for them; however, only 27.4% stated they would have intercalated if fees had been £9000 per annum. Conclusions Students clearly value intercalated degrees, feel they gained a substantial advantage over their peers as well as skills helpful for their future careers. The rise in tuition fees is likely to reduce the number of medical students opting to undertake an intercalated degree, and could result in a further reduction in numbers following an academic path. Sheffield University have more intercalating students supervised by clinical academics. Clinical academics appear more effective as supervisors for medical students undertaking an intercalated degree in terms of results and additional academic sequelae. PMID:23355672

ELECTROLYTIC DECHLORINATION OF 2-CHLOROBIPHENYL AT A PALLADIUM MODIFIED GRANULAR-GRAPHITE-PACKED ELECTRODE

EPA Science Inventory

Polychlorinated biphenyls (PCBs) and other chlorinated aromatic compounds are distributed in soils and sediments at over 400 sites in the USA. A national need exists for both in situ and ex situ methods to destroy these persistent organic pollutants in soils and sediments at ambi...

A photoactive bimetallic framework for direct aminoformylation of nitroarenes

EPA Science Inventory

A bimetallic catalyst, AgPd@g-C3N4, was synthesized by immobilizing silver and palladium nanoparticles over the surface of graphitic carbon nitride (g-C3N4) and its utility was demonstrated for the concerted aminoformylation of aromatic nitro compounds under visible light conditi...

Genotoxicity of diphenyl diselenide in bacteria and yeast.

PubMed

Rosa, Renato Moreira; Sulzbacher, Krisley; Picada, Jaqueline Nascimento; Roesler, Rafael; Saffi, Jenifer; Brendel, Martin; Henriques, João Antonio Pêgas

2004-10-10

Diphenyl diselenide (DPDS) is an electrophilic reagent used in the synthesis of a variety of pharmacologically active organic selenium compounds. This may increase the risk of human exposure to the chemical at the workplace. We have determined its mutagenic potential in the Salmonella/microsome assay and used the yeast Saccharomyces cerevisiae to assay for putative genotoxicity, recombinogenicity and to determine whether DNA damage produced by DPDS is repairable. Only in exponentially growing cultures was DPDS able to induce frameshift mutations in S. typhimurium and haploid yeast and to increase crossing over and gene conversion frequencies in diploid strains of S. cerevisiae. Thus, DPDS presents a behavior similar to that of an intercalating agent. Mutants defective in excision-resynthesis repair (rad3, rad1), in error-prone repair (rad6) and in recombinational repair (rad52) showed higher than WT-sensitivity to DPDS. It appears that this compound is capable of inducing single and/or double strand breaks in DNA. An epistatic interaction was shown between rad3-e5 and rad52-1 mutant alleles, indicating that excision-resynthesis and strand-break repair may possess common steps in the repair of DNA damage induced by DPDS. DPDS was able to enhance the mutagenesis induced by oxidative mutagens in bacteria. N-acetylcysteine, a glutathione biosynthesis precursor, prevented mutagenesis induced by DPDS in yeast. We have shown that DPDS is a weak mutagen which probably generates DNA strand breaks through both its intercalating action and pro-oxidant effect.

Dynamics of DNA/intercalator complexes

NASA Astrophysics Data System (ADS)

Schurr, J. M.; Wu, Pengguang; Fujimoto, Bryant S.

1990-05-01

Complexes of linear and supercoiled DNAs with different intercalating dyes are studied by time-resolved fluorescence polarization anisotropy using intercalated ethidium as the probe. Existing theory is generalized to take account of excitation transfer between intercalated ethidiums, and Forster theory is shown to be valid in this context. The effects of intercalated ethidium, 9-aminoacridine, and proflavine on the torsional rigidity of linear and supercoiled DNAs are studied up to rather high binding ratios. Evidence is presented that metastable secondary structure persists in dye-relaxed supercoiled DNAs, which contradicts the standard model of supercoiled DNAs.

A Novel Battery Cathode Material Based on intercalation Chemistry: Redox Reactions of the 2,5-Dimercapto-1,3,4-Thiadiazole/V2O5 Xerogel System

DTIC Science & Technology

1998-06-29

of some interstitial water during intercalation of the disulfide polymer of DMcT. Elemental analysis gives a composition for the intercalation...the disulfide polymer of DMcT. Elemental analysis gives a composition for the intercalation material of [(polyDMcT)o25*V205𔃻.4H20]. The cyclic...13.5 A). This change is consistent with loss of some interstitial water during intercalation of the disulfide polymer of DMcT. Elemental analysis