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Sample records for enhanced metal organic

  1. Metallic nanoparticle deposition techniques for enhanced organic photovoltaic cells

    NASA Astrophysics Data System (ADS)

    Cacha, Brian Joseph Gonda

    Energy generation via organic photovoltaic (OPV) cells provide many advantages over alternative processes including flexibility and price. However, more efficient OPVs are required in order to be competitive for applications. One way to enhance efficiency is through manipulation of exciton mechanisms within the OPV, for example by inserting a thin film of bathocuproine (BCP) and gold nanoparticles between the C60/Al and ZnPc/ITO interfaces, respectively. We find that BCP increases efficiencies by 330% due to gains of open circuit voltage (Voc) by 160% and short circuit current (Jsc) by 130%. However, these gains are complicated by the anomalous photovoltaic effect and an internal chemical potential. Exploration in the tuning of metallic nanoparticle deposition on ITO was done through four techniques. Drop casting Ag nanoparticle solution showed arduous control on deposited morphology. Spin-coating deposited very low densities of nanoparticles. Drop casting and spin-coating methods showed arduous control on Ag nanoparticle morphology due to clustering and low deposition density, respectively. Sputtered gold on glass was initially created to aid the adherence of Ag nanoparticles but instead showed a quick way to deposit aggregated gold nanoparticles. Electrodeposition of gold nanoparticles (AuNP) proved a quick method to tune nanoparticle morphology on ITO substrates. Control of deposition parameters affected AuNP size and distribution. AFM images of electrodeposited AuNPs showed sizes ranging from 39 to 58 nm. UV-Vis spectroscopy showed the presence of localized plasmon resonance through absorption peaks ranging from 503 to 614 nm. A linear correlation between electrodeposited AuNP size and peak absorbance was seen with a slope of 3.26 wavelength(nm)/diameter(nm).

  2. Regulating the spatial distribution of metal nanoparticles within metal-organic frameworks to enhance catalytic efficiency

    PubMed Central

    Yang, Qiu; Liu, Wenxian; Wang, Bingqing; Zhang, Weina; Zeng, Xiaoqiao; Zhang, Cong; Qin, Yongji; Sun, Xiaoming; Wu, Tianpin; Liu, Junfeng; Huo, Fengwei; Lu, Jun

    2017-01-01

    Composites incorporating metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) have broad applications in many fields. However, the controlled spatial distribution of the MNPs within MOFs remains a challenge for addressing key issues in catalysis, for example, the efficiency of catalysts due to the limitation of molecular diffusion within MOF channels. Here we report a facile strategy that enables MNPs to be encapsulated into MOFs with controllable spatial localization by using metal oxide both as support to load MNPs and as a sacrificial template to grow MOFs. This strategy is versatile to a variety of MNPs and MOF crystals. By localizing the encapsulated MNPs closer to the surface of MOFs, the resultant MNPs@MOF composites not only exhibit effective selectivity derived from MOF cavities, but also enhanced catalytic activity due to the spatial regulation of MNPs as close as possible to the MOF surface. PMID:28195131

  3. Regulating the spatial distribution of metal nanoparticles within metal-organic frameworks to enhance catalytic efficiency

    NASA Astrophysics Data System (ADS)

    Yang, Qiu; Liu, Wenxian; Wang, Bingqing; Zhang, Weina; Zeng, Xiaoqiao; Zhang, Cong; Qin, Yongji; Sun, Xiaoming; Wu, Tianpin; Liu, Junfeng; Huo, Fengwei; Lu, Jun

    2017-02-01

    Composites incorporating metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) have broad applications in many fields. However, the controlled spatial distribution of the MNPs within MOFs remains a challenge for addressing key issues in catalysis, for example, the efficiency of catalysts due to the limitation of molecular diffusion within MOF channels. Here we report a facile strategy that enables MNPs to be encapsulated into MOFs with controllable spatial localization by using metal oxide both as support to load MNPs and as a sacrificial template to grow MOFs. This strategy is versatile to a variety of MNPs and MOF crystals. By localizing the encapsulated MNPs closer to the surface of MOFs, the resultant MNPs@MOF composites not only exhibit effective selectivity derived from MOF cavities, but also enhanced catalytic activity due to the spatial regulation of MNPs as close as possible to the MOF surface.

  4. Optical design of transparent metal grids for plasmonic absorption enhancement in ultrathin organic solar cells.

    PubMed

    Kim, Inho; Lee, Taek Seong; Jeong, Doo Seok; Lee, Wook Seong; Kim, Won Mok; Lee, Kyeong-Seok

    2013-07-01

    Transparent metal grid combining with plasmonic absorption enhancement is a promising replacement to indium tin oxide thin films. We numerically demonstrate metal grids in one or two dimension lead to plasmonic absorption enhancements in ultrathin organic solar cells. In this paper, we study optical design of metal grids for plasmonic light trapping and identify different plasmonic modes of the surface plasmon polaritons excited at the interfaces of glass/metal grids, metal grids/active layers, and the localized surface plasmon resonance of the metal grids using numerical calculations. One dimension metal grids with the optimal design of a width and a period lead to the absorption enhancement in the ultrathin active layers of 20 nm thickness by a factor of 2.6 under transverse electric polarized light compared to the case without the metal grids. Similarly, two dimensional metal grids provide the absorption enhancement by a factor of 1.8 under randomly polarized light.

  5. Superconducting fluctuations in organic molecular metals enhanced by Mott criticality.

    PubMed

    Nam, Moon-Sun; Mézière, Cécile; Batail, Patrick; Zorina, Leokadiya; Simonov, Sergey; Ardavan, Arzhang

    2013-12-02

    Unconventional superconductivity typically occurs in materials in which a small change of a parameter such as bandwidth or doping leads to antiferromagnetic or Mott insulating phases. As such competing phases are approached, the properties of the superconductor often become increasingly exotic. For example, in organic superconductors and underdoped high-T(c) cuprate superconductors a fluctuating superconducting state persists to temperatures significantly above T(c). By studying alloys of quasi-two-dimensional organic molecular metals in the κ-(BEDT-TTF)₂X family, we reveal how the Nernst effect, a sensitive probe of superconducting phase fluctuations, evolves in the regime of extreme Mott criticality. We find strong evidence that, as the phase diagram is traversed through superconductivity towards the Mott state, the temperature scale for superconducting fluctuations increases dramatically, eventually approaching the temperature at which quasiparticles become identifiable at all.

  6. The emerging multiple metal nanostructures for enhancing the light trapping of thin film organic photovoltaic cells.

    PubMed

    Choy, Wallace C H

    2014-10-18

    Recently, various metal nanostructures have been introduced into organic solar cells (OSCs) for performance enhancement. Here, we review the recent progress in OSCs incorporated with multiple metal nanostructures including various metal nanopatterns and metal nanomaterials. Multiple physical effects arise from these incorporated nanostructures, which require careful distinction. Changes induced by the metal nanostructures are examined in detail from the optical and electrical aspects. With the comprehensive understanding of the physical mechanisms for various metal nanostructures, further improvement in device performance and emerging applications can be expected for the new class of nanostructure-incorporated OSCs.

  7. Unprecedented Li(+) Exchange in an Anionic Metal-Organic Framework: Significantly Enhanced Gas Uptake Capacity.

    PubMed

    Liu, Bo; Zhang, Rui; Pan, Chun-Yang; Jiang, Hai-Long

    2017-04-17

    We herein report the first example of Li(+) exchanged with both the guest H2N(Me)2(+) cations located in the channels and the coordinated metal ions from an anionic metal-organic framework (MOF), leading to significant enhancement of the pore volume and gas sorption abilities of the exchanged MOF. Furthermore, both MOFs before and after Li(+) exchange show good selective adsorption for CO2 over CH4.

  8. Nanoscale Fluorescent Metal-Organic Framework@Microporous Organic Polymer Composites for Enhanced Intracellular Uptake and Bioimaging.

    PubMed

    Wang, Lei; Wang, Weiqi; Zheng, Xiaohua; Li, Zhensheng; Xie, Zhigang

    2017-01-26

    Polymer-modified metal-organic frameworks combine the advantages of both soft polymers and crystalline metal-organic frameworks (MOFs). It is a big challenge to develop simple methods for surface modification of MOFs. In this work, MOF@microporous organic polymer (MOP) hybrid nanoparticles (UNP) have been synthesized by epitaxial growth of luminescent boron-dipyrromethene (BODIPYs)-imine MOPs on the surface of UiO-MOF seeds, which exhibit low cytotoxicity, smaller size distribution, well-retained pore integrity, and available functional sites. After folic acid grafting, the enhanced intracellular uptake and bioimaging was validated. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Mechanism of optical absorption enhancement in thin film organic solar cells with plasmonic metal nanoparticles.

    PubMed

    Qu, Di; Liu, Fang; Huang, Yidong; Xie, Wanlu; Xu, Qi

    2011-11-21

    The optical absorption enhancement in thin film organic solar cells (OSCs) with plasmonic metal nanoparticles (NPs) has been studied by means of finite element method with a three-dimension model. It is found that significant plasmonic enhancement of above 100% can be obtained by introducing Ag-NPs at the interface between P3HT:PCBM active layer and PEDOT:PSS anode layer. This enhancement is even larger than that with Ag-NPs totally embedded in the P3HT:PCBM active layer of thin film OSCs. Furthermore, the enhancement mechanism of Ag-NPs at different positions of thin film OSCs is investigated.

  10. Effective medium analysis of absorption enhancement in short-pitch metal grating incorporated organic solar cells.

    PubMed

    Zhang, Ye; Cui, Yanxia; Wang, Wenyan; Fung, Kin Hung; Ji, Ting; Hao, Yuying; Zhu, Furong

    2016-10-31

    The effective medium theory is applied to analyze the absorption enhancement in organic solar cells with a short-pitch metal grating. A 37% improvement in the absorption of the active layer is achieved with respect to that of a planar control cell. It is inspired that the propagating surface plasmon modes are excited at the interface between the effective medium layer and the flat metal plate, resulting in a reduction of light reflection. In real structure, the electric field redistributes with its intensity in the region with active materials infiltrated in the grooves increases significantly, exhibiting like hot spots to assist in achieving broadband absorption enhancement. Moreover, the localized surface plasmon resonances excited at the top of the metal ridges also contribute to the absorption enhancement in the cells.

  11. Suppressing molecular motions for enhanced room-temperature phosphorescence of metal-free organic materials

    PubMed Central

    Kwon, Min Sang; Yu, Youngchang; Coburn, Caleb; Phillips, Andrew W.; Chung, Kyeongwoon; Shanker, Apoorv; Jung, Jaehun; Kim, Gunho; Pipe, Kevin; Forrest, Stephen R.; Youk, Ji Ho; Gierschner, Johannes; Kim, Jinsang

    2015-01-01

    Metal-free organic phosphorescent materials are attractive alternatives to the predominantly used organometallic phosphors but are generally dimmer and are relatively rare, as, without heavy-metal atoms, spin–orbit coupling is less efficient and phosphorescence usually cannot compete with radiationless relaxation processes. Here we present a general design rule and a method to effectively reduce radiationless transitions and hence greatly enhance phosphorescence efficiency of metal-free organic materials in a variety of amorphous polymer matrices, based on the restriction of molecular motions in the proximity of embedded phosphors. Covalent cross-linking between phosphors and polymer matrices via Diels–Alder click chemistry is devised as a method. A sharp increase in phosphorescence quantum efficiency is observed in a variety of polymer matrices with this method, which is ca. two to five times higher than that of phosphor-doped polymer systems having no such covalent linkage. PMID:26626796

  12. Suppressing molecular motions for enhanced room-temperature phosphorescence of metal-free organic materials

    NASA Astrophysics Data System (ADS)

    Kwon, Min Sang; Yu, Youngchang; Coburn, Caleb; Phillips, Andrew W.; Chung, Kyeongwoon; Shanker, Apoorv; Jung, Jaehun; Kim, Gunho; Pipe, Kevin; Forrest, Stephen R.; Youk, Ji Ho; Gierschner, Johannes; Kim, Jinsang

    2015-12-01

    Metal-free organic phosphorescent materials are attractive alternatives to the predominantly used organometallic phosphors but are generally dimmer and are relatively rare, as, without heavy-metal atoms, spin-orbit coupling is less efficient and phosphorescence usually cannot compete with radiationless relaxation processes. Here we present a general design rule and a method to effectively reduce radiationless transitions and hence greatly enhance phosphorescence efficiency of metal-free organic materials in a variety of amorphous polymer matrices, based on the restriction of molecular motions in the proximity of embedded phosphors. Covalent cross-linking between phosphors and polymer matrices via Diels-Alder click chemistry is devised as a method. A sharp increase in phosphorescence quantum efficiency is observed in a variety of polymer matrices with this method, which is ca. two to five times higher than that of phosphor-doped polymer systems having no such covalent linkage.

  13. Collaborative interactions to enhance gas binding energy in porous metal-organic frameworks.

    PubMed

    Lin, Rui-Biao; Chen, Banglin

    2017-03-01

    Metal-organic frameworks (MOFs) are potentially useful materials for hydrogen and methane storage. However, the weak interactions between the MOF host and gas guest molecules have limited their storage capacities at elevated temperatures. In this issue, Alkordi et al. [IUCrJ (2017), 4, 131-135] illustrate an example of a porous MOF with a suitable pore size and unique pore surface for enhanced interaction with hydrogen molecules, providing the promise of further increasing the gas binding affinity through collaborative interactions.

  14. Broadband absorption enhancement of organic solar cells with interstitial lattice patterned metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Luzhou; Choy, Wallace C. H.; Sha, Wei E. I.

    2013-06-01

    Light blocking induced by top patterned nanostructures is a fundamental limit in solar cells absorption. Here we propose an interstitial lattice patterned organic solar cell which can improve the light blocking of traditional square lattice and achieve broadband absorption enhancement. Compared to square lattice design, the plasmonic mode couplings between individual metallic nanoparticles in the interstitial lattice are more versatile and much stronger. Moreover, plasmonic modes can couple to the guided modes, resulting in large enhancement factor at some wavelengths. The interstitial lattice concept will be a broad interest and great help for high-performance photovoltaics.

  15. Metallated metal-organic frameworks

    DOEpatents

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

    2017-08-22

    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  16. Metallated metal-organic frameworks

    DOEpatents

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

    2017-02-07

    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  17. Fluorous Metal-Organic Frameworks with Enhanced Stability and High H2/CO2 Storage Capacities

    PubMed Central

    Zhang, Da-Shuai; Chang, Ze; Li, Yi-Fan; Jiang, Zhong-Yi; Xuan, Zhi-Hong; Zhang, Ying-Hui; Li, Jian-Rong; Chen, Qiang; Hu, Tong-Liang; Bu, Xian-He

    2013-01-01

    A new class of metal-organic frameworks (MOFs) has been synthesized by ligand-functionalization strategy. Systematic studies of their adsorption properties were performed at low and high pressure. Importantly, when fluorine was introduced into the framework via the functionalization, both the framework stabilities and adsorption capacities towards H2/CO2 were enhanced significantly. This consequence can be well interpreted by theoretical studies of these MOFs structures. In addition, one of these MOFs TKL-107 was used to fabricate mixed matrix membranes, which exhibit great potential for the application of CO2 separation. PMID:24264725

  18. Electron accumulation on metal nanoparticles in plasmon-enhanced organic solar cells.

    PubMed

    Salvador, Michael; MacLeod, Bradley A; Hess, Angela; Kulkarni, Abhishek P; Munechika, Keiko; Chen, Jennifer I L; Ginger, David S

    2012-11-27

    Plasmonic metal nanoparticles have been used to enhance the performance of thin-film devices such as organic photovoltaics based on polymer/fullerene blends. We show that silver nanoprisms accumulate long-lived negative charges when they are in contact with a photoexcited bulk heterojunction blend composed of poly(3-hexylthiophene)/phenyl-C61-butyric acid methyl ester (P3HT/PCBM). We report both the charge modulation and electroabsorption spectra of silver nanoprisms in solid-state devices and compare these spectra with the photoinduced absorption spectra of P3HT/PCBM blends containing silver nanoprisms. We assign a previously unidentified peak in the photoinduced absorption spectra to the presence of photoinduced electrons on the silver nanoprisms. We show that coating the nanoprisms with a 2.5 nm thick insulating layer can completely inhibit this charging. These results may inform methods for limiting metal-mediated losses in plasmonic solar cells.

  19. Enhanced Cooperativity in Supported Spin-Crossover Metal-Organic Frameworks.

    PubMed

    Groizard, Thomas; Papior, Nick; Le Guennic, Boris; Robert, Vincent; Kepenekian, Mikaël

    2017-07-20

    The impact of surface deposition on cooperativity is explored in Au(111)-supported self-assembled metal-organic frameworks (MOFs) based on Fe(II) ions. Using a thermodynamic model, we first demonstrate that dimensionality reduction combined with deposition on a metal surface is likely to deeply enhance the spin-crossover cooperativity, going from γ3D = 16 K for the bulk material to γ2D(supp) = 386 K for its 2D supported derivative. On the basis of density functional theory, we then elucidate the electronic structure of a promising Fe-based MOF. A chemical strategy is proposed to turn a weakly interacting magnetic system into a strongly cooperative spin-crossover monolayer with γMOF(Au(111)) = 83 K. These results open a promising route to the fabrication of cooperative materials based on SCO Fe(II) platforms.

  20. Plasmonic nanopatch array with integrated metal-organic framework for enhanced infrared absorption gas sensing

    NASA Astrophysics Data System (ADS)

    Chong, Xinyuan; Kim, Ki-joong; Zhang, Yujing; Li, Erwen; Ohodnicki, Paul R.; Chang, Chih-Hung; Wang, Alan X.

    2017-06-01

    In this letter, we present a nanophotonic device consisting of plasmonic nanopatch array (NPA) with integrated metal-organic framework (MOF) for enhanced infrared absorption gas sensing. By designing a gold NPA on a sapphire substrate, we are able to achieve enhanced optical field that spatially overlaps with the MOF layer, which can adsorb carbon dioxide (CO2) with high capacity. Experimental results show that this hybrid plasmonic-MOF device can effectively increase the infrared absorption path of on-chip gas sensors by more than 1100-fold. The demonstration of infrared absorption spectroscopy of CO2 using the hybrid plasmonic-MOF device proves a promising strategy for future on-chip gas sensing with ultra-compact size.

  1. Flexible Organic Phototransistor Array with Enhanced Responsivity via Metal-Ligand Charge Transfer.

    PubMed

    Liu, Xien; Lee, Eun Kwang; Kim, Dong Yeong; Yu, Hojeong; Oh, Joon Hak

    2016-03-23

    Phototransistors based on organic photoactive materials combine tunable light absorption in the spectral region from ultraviolet to near-infrared with low-temperature processability over large areas on flexible substrates. However, they often exhibit low photoresponsivity because of low molar extinction coefficient of photoactive components. We report a simple, yet highly efficient solution method for enhancing the performance of organic phototransistors using ruthenium complex 1 (Ru-complex 1). An air-stable n-type organic semiconductor, N,N'-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI), has been deposited on a silicon wafer and a transparent polyimide (PI) substrate via thermal evaporation under vacuum. The BPE-PTCDI phototransistors functionalized with Ru-complex 1 exhibit ∼5000 times higher external quantum efficiency (EQE) than that of pristine BPE-PTCDI phototransistors, owing to the metal-ligand charge transfer (MLCT) from Ru-complex 1 to the active component of the device. In addition, a large 10 × 10 phototransistor array (2.5 × 2.5 cm(2)) has been prepared on a transparent PI substrate, showing distinct light mapping. The fabricated phototransistor array is highly flexible and twistable and works well under tensile and compressive strains. We believe that our simple method will pave a viable way for improvements in the photoresponsivity of organic semiconductors for applications in wearable organic optoelectronic devices.

  2. On Absorption-Enhanced Organic Photovoltaic By Incorporating Metallic Nano Pyramid Particles

    NASA Astrophysics Data System (ADS)

    Qasem, Hussamaldeen Saif

    A lattice structure of metallic Nano pyramids (NPY) particles was planted on the interface between hole transport layer (HTL) and the transparent conductive layer (TCL) of an organic photovoltaic (OPV) cell. Standard metal evaporation along with Nano sphere lithography was used to grow the metallic NPY mesh structure. Silver (Ag) and Gold (Au) were the primary choice of the NPY mesh structure due to the excellent overlap of their peak localized surface Plasmon resonance (LSPR) frequency with the active layer absorption wavelengths. The current-voltage curve displayed an improvement in the efficiency and fill factor values of OPVs that used NPY lattice structure over devices that used regular sphere-shaped Nano particles. Despite the better-shaped and strong (LSPR) peak frequency of the Ag NPY lattice structure, Au NPY lattice structure exhibited an enhanced absorption and overall efficiency, which was owed to the wider (LSPR) frequency peak that Au possesses. The effect of NPY lattice structure could be further investigated with several approaches such as using different NPY materials, using core-shill approach, and growing the NPY on different layers or interfaces.

  3. Plasmon-Enhanced Photocatalytic CO(2) Conversion within Metal-Organic Frameworks under Visible Light.

    PubMed

    Choi, Kyung Min; Kim, Dohyung; Rungtaweevoranit, Bunyarat; Trickett, Christopher A; Barmanbek, Jesika Trese Deniz; Alshammari, Ahmad S; Yang, Peidong; Yaghi, Omar M

    2017-01-11

    Materials development for artificial photosynthesis, in particular, CO2 reduction, has been under extensive efforts, ranging from inorganic semiconductors to molecular complexes. In this report, we demonstrate a metal-organic framework (MOF)-coated nanoparticle photocatalyst with enhanced CO2 reduction activity and stability, which stems from having two different functional units for activity enhancement and catalytic stability combined together as a single construct. Covalently attaching a CO2-to-CO conversion photocatalyst Re(I)(CO)3(BPYDC)Cl, BPYDC = 2,2'-bipyridine-5,5'-dicarboxylate, to a zirconium MOF, UiO-67 (Ren-MOF), prevents dimerization leading to deactivation. By systematically controlling its density in the framework (n = 0, 1, 2, 3, 5, 11, 16, and 24 complexes per unit cell), the highest photocatalytic activity was found for Re3-MOF. Structural analysis of Ren-MOFs suggests that a fine balance of proximity between photoactive centers is needed for cooperatively enhanced photocatalytic activity, where an optimum number of Re complexes per unit cell should reach the highest activity. Based on the structure-activity correlation of Ren-MOFs, Re3-MOF was coated onto Ag nanocubes (Ag⊂Re3-MOF), which spatially confined photoactive Re centers to the intensified near-surface electric fields at the surface of Ag nanocubes, resulting in a 7-fold enhancement of CO2-to-CO conversion under visible light with long-term stability maintained up to 48 h.

  4. Enhanced ethylene separation and plasticization resistance in polymer membranes incorporating metal-organic framework nanocrystals

    NASA Astrophysics Data System (ADS)

    Bachman, Jonathan E.; Smith, Zachary P.; Li, Tao; Xu, Ting; Long, Jeffrey R.

    2016-08-01

    The implementation of membrane-based separations in the petrochemical industry has the potential to reduce energy consumption significantly relative to conventional separation processes. Achieving this goal, however, requires the development of new membrane materials with greater selectivity, permeability and stability than available at present. Here, we report composite materials consisting of nanocrystals of metal-organic frameworks dispersed within a high-performance polyimide, which can exhibit enhanced selectivity for ethylene over ethane, greater ethylene permeability and improved membrane stability. Our results suggest that framework-polymer interactions reduce chain mobility of the polymer while simultaneously boosting membrane separation performance. The increased stability, or plasticization resistance, is expected to improve membrane utility under real process conditions for petrochemical separations and natural gas purification. Furthermore, this approach can be broadly applied to numerous polymers that encounter aggressive environments, potentially making gas separations possible that were previously inaccessible to membranes.

  5. Ligand Functionalization in Metal-Organic Frameworks for Enhanced Carbon Dioxide Adsorption.

    PubMed

    Wang, Hao; Peng, Junjie; Li, Jing

    2016-06-01

    Ligand functionalization in metal-organic frameworks (MOFs) has been studied extensively and has been demonstrated to enhance gas adsorption and induce interesting gas adsorption phenomena. This account summarizes our recent study of three series of MOFs by ligand functionalization, as well as their carbon dioxide adsorption properties. While ligand functionalization does not change the overall structure of the frameworks, it can influence their gas adsorption behavior. In the first two series, we show how ligand functionalization influences the CO2 affinity and adsorption capacity of MOFs. We also show a special case in which subtle changes in ligand functionality alter the CO2 adsorption profile. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Enhanced ethylene separation and plasticization resistance in polymer membranes incorporating metal-organic framework nanocrystals.

    PubMed

    Bachman, Jonathan E; Smith, Zachary P; Li, Tao; Xu, Ting; Long, Jeffrey R

    2016-08-01

    The implementation of membrane-based separations in the petrochemical industry has the potential to reduce energy consumption significantly relative to conventional separation processes. Achieving this goal, however, requires the development of new membrane materials with greater selectivity, permeability and stability than available at present. Here, we report composite materials consisting of nanocrystals of metal-organic frameworks dispersed within a high-performance polyimide, which can exhibit enhanced selectivity for ethylene over ethane, greater ethylene permeability and improved membrane stability. Our results suggest that framework-polymer interactions reduce chain mobility of the polymer while simultaneously boosting membrane separation performance. The increased stability, or plasticization resistance, is expected to improve membrane utility under real process conditions for petrochemical separations and natural gas purification. Furthermore, this approach can be broadly applied to numerous polymers that encounter aggressive environments, potentially making gas separations possible that were previously inaccessible to membranes.

  7. Energy transfer from quantum dots to metal-organic frameworks for enhanced light harvesting.

    PubMed

    Jin, Shengye; Son, Ho-Jin; Farha, Omar K; Wiederrecht, Gary P; Hupp, Joseph T

    2013-01-23

    Because of their efficient energy-transport properties, porphyrin-based metal-organic frameworks (MOFs) are attractive compounds for solar photochemistry applications. However, their absorption bands provide limited coverage in the visible spectral range for light-harvesting applications. We report here the functionalization of porphyrin-based MOFs with CdSe/ZnS core/shell quantum dots (QDs) for the enhancement of light harvesting via energy transfer from the QDs to the MOFs. The broad absorption band of the QDs in the visible region offers greater coverage of the solar spectrum by QD-MOF hybrid structures. We show through time-resolved emission studies that photoexcitation of the QDs is followed by energy transfer to the MOFs with efficiencies of more than 80%. This sensitization approach can result in a >50% increase in the number of photons harvested by a single monolayer MOF structure with a monolayer of QDs on the surface of the MOF.

  8. Enhanced surface losses of organic solar cells induced by efficient polaron pair dissociation at the metal/organic interface

    NASA Astrophysics Data System (ADS)

    Yang, Wenchao; Li, De-Li; Yao, Yao; Hou, Xiaoyuan; Wu, Chang-Qin

    2012-08-01

    As a growing importance is placed on developing more efficient organic solar cells, understanding the behavior of free charge carriers at the metal/organic (M/O) interface is critical. One of the current challenges is understanding surface losses, essentially the loss of free charge carriers at the electrode/organic interface. In this paper, we use device model simulations to study such phenomena and we pay particular attention to the role of polaron pair (PP) M/O interfacial dissociation. The origin of surface losses is through the extraction of free charge carriers from the wrong electrodes, or direct surface recombination of PPs. Through simulation, we find that a high injection barrier leads to a large surface loss. In addition, surface loss increases with both the interfacial dissociation rate and PP diffusivity. Efficient interfacial dissociation can significantly enhance surface losses if the PP diffusivity is relatively large. Furthermore, current voltage characteristics reveal that surface losses undermine the device operating parameters and efficiency. Interlayers inserted at the M/O interface could block wrong electrode carriers, suppress the interfacial dissociation and reduce surface losses.

  9. Tuning Metal-Organic Frameworks with Open-Metal Sites and Its Origin for Enhancing CO2 Affinity by Metal Substitution.

    PubMed

    Park, Joonho; Kim, Heejin; Han, Sang Soo; Jung, Yousung

    2012-04-05

    Reducing anthropogenic carbon emission is a problem that requires immediate attention. Metal-organic frameworks (MOFs) have emerged as a promising new materials platform for carbon capture, of which Mg-MOF-74 offers chemospecific affinity toward CO2 because of the open Mg sites. Here we tune the binding affinity of CO2 for M-MOF-74 by metal substitution (M = Mg, Ca, and the first transition metal elements) and show that Ti- and V-MOF-74 can have an enhanced affinity compared to Mg-MOF-74 by 6-9 kJ/mol. Electronic structure calculations suggest that the origin of the major affinity trend is the local electric field effect of the open metal site that stabilizes CO2, but forward donation from the lone-pair electrons of CO2 to the empty d-levels of transition metals as in a weak coordination bond makes Ti and V have an even higher binding strength than Mg, Ca, and Sc.

  10. Enhancing Skin Permeation of Biphenylacetic Acid (BPA) Using Salt Formation with Organic and Alkali Metal Bases

    PubMed Central

    Pawar, Vijay; Naik, Prashant; Giridhar, Rajani; Yadav, Mange Ram

    2015-01-01

    In the present study, a series of organic and alkali metal salts of biphenylacetic acid (BPA) have been prepared and evaluated in vitro for percutaneous drug delivery. The physicochemical properties of BPA salts were determined using solubility measurements, DSC, and IR. The DSC thermogram and FTIR spectra confirmed the salt formation with organic and alkali metal bases. Among the series, salts with organic amines (ethanolamine, diethanolamine, triethanolamine, and diethylamine) had lowered melting points while the alkali metal salt (sodium) had a higher melting point than BPA. The in vitro study showed that salt formation improves the physicochemical properties of BPA, leading to improved permeability through the skin. Amongst all the prepared salts, ethanolamine salt (1b) showed 7.2- and 5.4-fold higher skin permeation than the parent drug at pH 7.4 and 5.0, respectively, using rat skin. PMID:26839810

  11. Functionalization of Metal-Organic Frameworks for Enhanced Stability under Humid Carbon Dioxide Capture Conditions.

    PubMed

    Andirova, Dinara; Lei, Yu; Zhao, Xiaodan; Choi, Sunho

    2015-10-26

    Metal-organic frameworks (MOFs) have been highlighted recently as promising materials for CO2 capture. However, in practical CO2 capture processes, such as capture from flue gas or ambient air, the adsorption properties of MOFs tend to be harmed by the presence of moisture possibly because of the hydrophilic nature of the coordinatively unsaturated sites (CUSs) within their framework. In this work, the CUSs of the MOF framework are functionalized with amine-containing molecules to prevent structural degradation in a humid environment. Specifically, the framework of the magnesium dioxybenzenedicarboxylate (Mg/DOBDC) MOF was functionalized with ethylenediamine (ED) molecules to make the overall structure less hydrophilic. Structural analysis after exposure to high-temperature steam showed that the ED-functionalized Mg/DOBDC (ED-Mg/DOBDC) is more stable under humid conditions, than Mg/DOBDC, which underwent drastic structural changes. ED-Mg/DOBDC recovered its CO2 adsorption capacity and initial adsorption rate quite well as opposed to the original Mg/DOBDC, which revealed a significant reduction in its capture capacity and kinetics. These results suggest that the amine-functionalization of the CUSs is an effective way to enhance the structural stability of MOFs as well as their capture of humid CO2 .

  12. Significantly enhanced hydrogen storage in metal-organic frameworks via spillover.

    PubMed

    Li, Yingwei; Yang, Ralph T

    2006-01-25

    The utilization of hydrogen in fuel-cell powered vehicles is limited by the lack of a safe and effective system for hydrogen storage. At the present time, there is no viable storage technology capable of meeting the DOE targets. Porous metal-organic frameworks (MOFs) are novel and potential candidates for hydrogen storage. Until now it is still not possible to achieve any significant hydrogen storage capacity in MOFs at ambient temperature. Here, we report, for the first time, significant amounts of hydrogen storage in MOF-5 and IRMOF-8 at ambient temperature by using a very simple technique via hydrogen dissociation and spillover. Thus, hydrogen uptakes for MOF-5 and IRMOF-8 can be enhanced by a factor of 3.3 and 3.1, respectively (to nearly 2 wt % at 10 MPa and 298 K). Furthermore, the isotherms are totally reversible. These findings suggest that our technique is suitable for hydrogen storage in a variety of MOF materials because of their similar structures as MOF-5 and IRMOF-8.

  13. Interaction of molecular hydrogen with open transition metal centers for enhanced binding in metal-organic frameworks: a computational study.

    PubMed

    Lochan, Rohini C; Khaliullin, Rustam Z; Head-Gordon, Martin

    2008-05-19

    Molecular hydrogen is known to form stable, "nonclassical" sigma complexes with transition metal centers that are stabilized by donor-acceptor interactions and electrostatics. In this computational study, we establish that strong H2 sorption sites can be obtained in metal-organic frameworks by incorporating open transition metal sites on the organic linkers. Using density functional theory and energy decomposition analysis, we investigate the nature and characteristics of the H2 interaction with models of exposed open metal binding sites {half-sandwich piano-stool shaped complexes of the form (Arene)ML(3- n)(H2)n [M=Cr, Mo, V(-), Mn(+); Arene = C6H5X (X=H, F, Cl, OCH3, NH2, CH3, CF3) or C6H3Y2X (Y=COOH, X=CF3, Cl; L=CO; n=1-3]}. The metal-H2 bond dissociation energy of the studied complexes is calculated to be between 48 and 84 kJ/mol, based on the introduction of arene substituents, changes to the metal core, and of charge-balancing ligands. Thus, design of the binding site controls the H2 binding affinity and could be potentially used to control the magnitude of the H2 interaction energy to achieve reversible sorption characteristics at ambient conditions. Energy decomposition analysis illuminates both the possibilities and present challenges associated with rational materials design.

  14. Thermally Stable Metal-Organic Framework-Templated Synthesis of Hierarchically Porous Metal Sulfides: Enhanced Photocatalytic Hydrogen Production.

    PubMed

    Xiao, Juan-Ding; Jiang, Hai-Long

    2017-07-01

    Porous nanostructured materials are demonstrated to be very promising in catalysis due to their well accessible active sites. Thermally stable metal-organic frameworks (MOFs) as hard templates are successfully utilized to afford porous metal oxides and subsequently metal sulfides by a nanocasting method. The resultant metal oxides/sulfides show considerable Brunauer-Emmett-Teller (BET) surface areas, by partially inheriting the pore character of MOF templates. Preliminary investigation on the obtained hierarchically porous CdS for water splitting, as a proof of concept, demonstrates its much higher activity than both corresponding bulk and nanosized counterparts, under visible light irradiation. Given the structural diversity and tailorability of MOFs, such synthetic approach may open an avenue to the synthesis of advanced porous materials for functional applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. One-pot synthesis of protein-embedded metal-organic frameworks with enhanced biological activities.

    PubMed

    Lyu, Fengjiao; Zhang, Yifei; Zare, Richard N; Ge, Jun; Liu, Zheng

    2014-10-08

    Protein molecules were directly embedded in metal-organic frameworks (MOFs) by a coprecipitation method. The protein molecules majorly embedded on the surface region of MOFs display high biological activities. As a demonstration of the power of such materials, the resulting Cyt c embedded in ZIF-8 showed a 10-fold increase in peroxidase activity compared to free Cyt c in solution and thus gave convenient, fast, and highly sensitive detection of trace amounts of explosive organic peroxides in solution.

  16. Analysis and optimization of surface plasmon-enhanced organic solar cells with a metallic crossed grating electrode.

    PubMed

    Lee, Eungkyu; Kim, Changsoon

    2012-09-10

    We perform a systematic analysis of enhanced short-circuit current density (J(sc) in organic solar cells (OSCs) where one metallic electrode is optically thick and the other consists of a two-dimensional metallic crossed grating. By examining a model device representative of such surface plasmon (SP)-enhanced OSCs by the Fourier modal and finite-element methods for electromagnetic and exciton diffusion calculations, respectively, we provide general guidelines to maximize J(sc) of the SP-enhanced OSCs. Based on this study, we optimize the performance of a small-molecule OSC employing a copper phthalocyanine-fullerene donor-acceptor pair, demonstrating that the optimized SP-enhanced device has J(sc) that is 75 % larger than that of the optimized device with an ITO-based conventional structure.

  17. Revisited design optimization of metallic gratings for plasmonic light-trapping enhancement in thin organic solar cells

    NASA Astrophysics Data System (ADS)

    Toan Dang, Phuc; Nguyen, Truong Khang; Le, Khai Q.

    2017-01-01

    We revisit previous studies of metallic gratings for optical absorption enhancement in an organic solar cell with a thin active layer. Our device geometry is designed for a real solar cell with full of functional layers. Various metallic gratings calibrated to generate periodic scatterers and low reflectors for broadband light account for increases in short circuit current density of up to 47% when compared to its flat counterpart. We found that the tapered grating has greater performance than the regular rectangular grating for transverse magnetic (TM) polarization while the latter shows better performance for transverse electric (TE) polarization. The overall metallic grating induced absorption enhancement was found at all angles of incidence. The best configuration was realized for the tapered grating-based solar cell at 25° of inclination.

  18. Simple way to engineer metal-semiconductor interface for enhanced performance of perovskite organic lead iodide solar cells.

    PubMed

    Xu, Yuzhuan; Shi, Jiangjian; Lv, Songtao; Zhu, Lifeng; Dong, Juan; Wu, Huijue; Xiao, Yin; Luo, Yanhong; Wang, Shirong; Li, Dongmei; Li, Xianggao; Meng, Qingbo

    2014-04-23

    A thin wide band gap organic semiconductor N,N,N',N'-tetraphenyl-benzidine layer has been introduced by spin-coating to engineer the metal-semiconductor interface in the hole-conductor-free perovskite solar cells. The average cell power conversion efficiency (PCE) has been enhanced from 5.26% to 6.26% after the modification and a highest PCE of 6.71% has been achieved. By the aid of electrochemical impedance spectroscopy and dark current analysis, it is revealed that this modification can increase interfacial resistance of CH3NH3PbI3/Au interface and retard electron recombination process in the metal-semiconductor interface.

  19. Ligand Symmetry Modulation for Designing a Mesoporous Metal-Organic Framework: Dual Reactivity to Transition and Lanthanide Metals for Enhanced Functionalization.

    PubMed

    Du, Miao; Wang, Xi; Chen, Min; Li, Cheng-Peng; Tian, Jia-Yue; Wang, Zhuo-Wei; Liu, Chun-Sen

    2015-06-26

    A promising alternative strategy for designing mesoporous metal-organic frameworks (MOFs) has been proposed, by modifying the symmetry rather than expanding the length of organic linkers. By means of this approach, a unique MOF material based on the target [Zn8(ad)4] (ad = adeninate) clusters and C3-symmetric organic linkers can be obtained, with trigonal microporous (ca., 0.8 nm) and hexagonal mesoporous (ca., 3.0 nm) 1D channels. Moreover, the resulting 446-MOF shows distinct reactivity to transition and lanthanide metal ions. Significantly, the transmetalation of Co(II) or Ni(II) on the Zn(II) centers in 446-MOF can enhance the sorption capacities of CO2 and CH4 (16-21%), whereas the impregnation of Eu(III) and Tb(III) in the channels of 446-MOF will result in adjustable light-emitting behaviors.

  20. Removal of heavy metals from contaminated soil by electrodialytic remediation enhanced with organic acids.

    PubMed

    Merdoud, Ouarda; Cameselle, Claudio; Boulakradeche, Mohamed Oualid; Akretche, Djamal Eddine

    2016-11-09

    The soil from an industrial area in Algeria was contaminated with Cr (8370 mg kg(-1)), Ni (1135 mg kg(-1)) and zinc (1200 mg kg(-1)). The electrodialytic remediation of this soil was studied using citric acid and EDTA as facilitating agents. 0.1 M citric acid or EDTA was added directly to the soil before it was introduced in an electrodialytic cell in an attempt to enhance the heavy metal solubility in the interstitial fluid. The more acidic pH in the soil when citric acid was used as the facilitating agent was not enough to mobilize and remove the metals from the soil. Only 7.2% of Ni and 6.7% of Zn were removed from the soil in the test with citric acid. The best results were found with EDTA, which was able to solubilize and complex Zn and Ni forming negatively charged complexes that were transported and accumulated in the anolyte. Complete removal was observed for Ni and Zn in the electrodialytic treatment with EDTA. Minor amounts of Cr were removed with both EDTA and citric acid.

  1. Performance Enhancement of Organic Light-Emitting Diodes Using Electron-Injection Materials of Metal Carbonates

    NASA Astrophysics Data System (ADS)

    Shin, Jong-Yeol; Kim, Tae Wan; Kim, Gwi-Yeol; Lee, Su-Min; Shrestha, Bhanu; Hong, Jin-Woong

    2016-05-01

    Performance of organic light-emitting diodes was investigated depending on the electron-injection materials of metal carbonates (Li2CO3 and Cs2CO3 ); and number of layers. In order to improve the device efficiency, two types of devices were manufactured by using the hole-injection material (Teflon-amorphous fluoropolymer -AF) and electron-injection materials; one is a two-layer reference device ( ITO/Teflon-AF/Alq3/Al ) and the other is a three-layer device (ITO/Teflon-AF/Alq3/metal carbonate/Al). From the results of the efficiency for the devices with hole-injection layer and electron-injection layer, it was found that the electron-injection layer affects the electrical properties of the device more than the hole-injection layer. The external-quantum efficiency for the three-layer device with Li2CO3 and Cs2CO3 layer is improved by approximately six and eight times, respectively, compared with that of the two-layer reference device. It is thought that a use of electron-injection layer increases recombination rate of charge carriers by the active injection of electrons and the blocking of holes.

  2. Electrocatalytic oxidation of small organic molecules in acid medium: enhancement of activity of noble metal nanoparticles and their alloys by supporting or modifying them with metal oxides

    PubMed Central

    Kulesza, Pawel J.; Pieta, Izabela S.; Rutkowska, Iwona A.; Wadas, Anna; Marks, Diana; Klak, Karolina; Stobinski, Leszek; Cox, James A.

    2013-01-01

    Different approaches to enhancement of electrocatalytic activity of noble metal nanoparticles during oxidation of small organic molecules (namely potential fuels for low-temperature fuel cells such as methanol, ethanol and formic acid) are described. A physical approach to the increase of activity of catalytic nanoparticles (e.g. platinum or palladium) involves nanostructuring to obtain highly dispersed systems of high surface area. Recently, the feasibility of enhancing activity of noble metal systems through the formation of bimetallic (e.g. PtRu, PtSn, and PdAu) or even more complex (e.g. PtRuW, PtRuSn) alloys has been demonstrated. In addition to possible changes in the electronic properties of alloys, specific interactions between metals as well as chemical reactivity of the added components have been postulated. We address and emphasize here the possibility of utilization of noble metal and alloyed nanoparticles supported on robust but reactive high surface area metal oxides (e.g. WO3, MoO3, TiO2, ZrO2, V2O5, and CeO2) in oxidative electrocatalysis. This paper concerns the way in which certain inorganic oxides and oxo species can act effectively as supports for noble metal nanoparticles or their alloys during electrocatalytic oxidation of hydrogen and representative organic fuels. Among important issues are possible changes in the morphology and dispersion, as well as specific interactions leading to the improved chemisorptive and catalytic properties in addition to the feasibility of long time operation of the discussed systems. PMID:24443590

  3. Metal Insertion in a Methylamine-Functionalized Zirconium Metal-Organic Framework for Enhanced Carbon Dioxide Capture.

    PubMed

    Gómora-Figueroa, A Paulina; Mason, Jarad A; Gonzalez, Miguel I; Bloch, Eric D; Meihaus, Katie R

    2017-03-27

    The reaction of ZrCl4 with 2',3',5',6'-tetramethylamino-p-terphenyl-4,4″-dicarboxylic acid (H2tpdc-4CH2NH2·3HCl) in the presence of NaF affords Zr6O4(OH)2.1F1.9(tpdc-4CH2NH2·3HCl)6 (1), which is a new member of the Zr6O4(OH)4(dicarboxylate linker)12 or UiO-68 family, and exhibits high porosity with BET and Langmuir surface areas of 1910 m(2)/g and 2220 m(2)/g, respectively. Remarkably, fluoride ion incorporation in the zirconium clusters results in increased thermal stability, marking the first example of enhancement in the stability of a UiO framework by this defect-restoration approach. Although material 1 features four alkylamine groups on each organic linker, the framework does not exhibit the high CO2 uptake that would be expected for reaction between CO2 and the amine groups to form carbamic acid or ammonium carbamate species. The absence of strong CO2 adsorption can likely be attributed to protonation at some of the amine sites and the presence of counterions. Indeed, exposure of material 1 to acetonitrile solutions of the organic bases 1,8-bis(dimethylamino)naphthalene (DMAN) or trimethylamine, affords a partially deprotonated material, which exhibits enhanced CO2 uptake. Exposure of basic amine sites also facilitates the postsynthetic chelation of copper(I) ([Cu(MeCN)4]·CF3SO3) to yield material 2 with an enhanced CO2 uptake of 4 wt % at 0.15 bar, which is double that of the parent framework 1.

  4. ENVIROMETAL TECHNOLOGIES, INC., METAL-ENHANCED DECHLORINATION OF VOLATILE ORGANIC COMPOUNDS USING AN IN-SITU REACTIVE IRON WALL

    EPA Science Inventory

    This report summarizes the results of a field demonstration conducted under the SITE program. The technology that was demonstrated was a metal-enhanced dechlorination process developed by EnviroMetal Technologies, Inc. to treat groundwater contaminated with chlorinated volatile ...

  5. Fabrication of gold nanoparticle-embedded metal-organic framework for highly sensitive surface-enhanced Raman scattering detection.

    PubMed

    Hu, Yuling; Liao, Jia; Wang, Dongmei; Li, Gongke

    2014-04-15

    Surface-enhanced Raman scattering (SERS) signals strongly rely on the interactions and distance between analyte molecules and metallic nanostructures. In this work, the use of a gold nanoparticle (AuNP)-embedded metal-organic framework was introduced for the highly sensitive SERS detection. The AuNPs were in situ grown and encapsulated within the host matrix of MIL-101 by a solution impregnation strategy. The as-synthesized AuNPs/MIL-101 nanocomposites combined the localized surface plasmon resonance properties of the gold nanoparticles and the high adsorption capability of metal-organic framework, making them highly sensitive SERS substrates by effectively preconcentrating analytes in close proximity to the electromagnetic fields at the SERS-active metal surface. We discussed the fabrication, physical characterization, and SERS activity of our novel substrates by measuring the Raman signals of a variety of model analytes. The SERS substrate was found to be highly sensitive, robust, and amiable to several different target analytes. A SERS detection limit of 41.75 and 0.54 fmol for Rhodamine 6G and benzadine, respectively, was demonstrated. The substrate also showed high stability and reproducibility, as well as molecular sieving effect thanks to the protective shell of the metal-organic framework. Subsequently, the potential practical application of the novel SERS substrate was evaluated by quantitative analysis of organic pollutant p-phenylenediamine in environmental water and tumor marker alpha-fetoprotein in human serum. The method showed good linearity between 1.0 and 100.0 ng/mL for p-phenylenediamine and 1.0-130.0 ng/mL for alpha-fetoprotein with the correlation coefficients of 0.9950 and -0.9938, respectively. The recoveries ranged from 80.5% to 114.7% for p-phenylenediamine in environmental water and 79.3% to 107.3% for alpha-fetoprotein in human serum. These results foresee promising application of the novel metal-organic framework based composites as

  6. Cation-induced kinetic trapping and enhanced hydrogen adsorption in a modulated anionic metal-organic framework.

    PubMed

    Yang, Sihai; Lin, Xiang; Blake, Alexander J; Walker, Gavin S; Hubberstey, Peter; Champness, Neil R; Schröder, Martin

    2009-09-01

    Metal-organic frameworks (MOFs)--microporous materials constructed by bridging metal centres with organic ligands--show promise for applications in hydrogen storage, which is a key challenge in the development of the 'hydrogen economy'. Their adsorption capacities, however, have remained insufficient for practical applications, and thus strategies to enhance hydrogen-MOF interactions are required. Here we describe an anionic MOF material built from In(III) centres and tetracarboxylic acid ligands (H(4)L) in which kinetic trapping behaviour--where hydrogen is adsorbed at high pressures but not released immediately on lowering the pressure--is modulated by guest cations. With piperazinium dications in its pores, the framework exhibits hysteretic hydrogen adsorption. On exchange of these dications with lithium cations, no hysteresis is seen, but instead there is an enhanced adsorption capacity coupled to an increase in the isosteric heat of adsorption. This is rationalized by the different locations of the cations within the pores, determined with precision by X-ray crystallography.

  7. Facile synthesis of glucoamylase embedded metal-organic frameworks (glucoamylase-MOF) with enhanced stability.

    PubMed

    Nadar, Shamraja S; Rathod, Virendra K

    2017-02-01

    The self-assembled glucoamylase metal-organic framework (glucoamylase-MOF) was synthesized by facile one-step method within 20min by simply mixing aqueous solution of 2-methylimidazole (160mM), glucoamylase (5mg/mL) and zinc acetate (40mM) at room temperature (28±2°C). The prepared glucoamylase-MOF was characterized by using FT-IR, confocal scanning laser microscopy, XRD and SEM. The robustness and thermal stability of glucoamylase embedded MOF was evaluated in terms of half-life (in the range of 60-80°C) which showed 6 folds increment as against free form. Further, in Michaelis-Menten kinetics studies, glucoamylase entrapped MOF exhibited higher Km value and lower Vmax value as compared to native enzyme. Moreover, the immobilized glucoamylase exhibited up to 57% of residual activity after six consecutive cycles of reuse, whereas it retained 91% of residual activity till 25days of storage. Finally, the conformational changes occurred after the encapsulation of glucoamylase in the interior of MOF, which was analyzed by using FT-IR data analysis tools. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Enhanced photochemical hydrogen production by a molecular diiron catalyst incorporated into a metal-organic framework.

    PubMed

    Pullen, Sonja; Fei, Honghan; Orthaber, Andreas; Cohen, Seth M; Ott, Sascha

    2013-11-13

    A molecular proton reduction catalyst [FeFe](dcbdt)(CO)6 (1, dcbdt = 1,4-dicarboxylbenzene-2,3-dithiolate) with structural similarities to [FeFe]-hydrogenase active sites has been incorporated into a highly robust Zr(IV)-based metal-organic framework (MOF) by postsynthetic exchange (PSE). The PSE protocol is crucial as direct solvothermal synthesis fails to produce the functionalized MOF. The molecular integrity of the organometallic site within the MOF is demonstrated by a variety of techniques, including X-ray absorption spectroscopy. In conjunction with [Ru(bpy)3](2+) as a photosensitizer and ascorbate as an electron donor, MOF-[FeFe](dcbdt)(CO)6 catalyzes photochemical hydrogen evolution in water at pH 5. The immobilized catalyst shows substantially improved initial rates and overall hydrogen production when compared to a reference system of complex 1 in solution. Improved catalytic performance is ascribed to structural stabilization of the complex when incorporated in the MOF as well as the protection of reduced catalysts 1(-) and 1(2-) from undesirable charge recombination with oxidized ascorbate.

  9. Selective Host-Guest Interaction between Metal Ions and Metal-Organic Frameworks Using Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy

    SciTech Connect

    Guo, Zhiyong; Kobayashi, Takeshi; Wang, Lin-Lin; Goh, Tian Wei; Xiao, Chaoxian; Caporini, Marc A.; Rosay, Melanie; Johnson, Duane D.; Pruski, Marek; Huang, Wenyu

    2014-10-08

    The host–guest interaction between metal ions (Pt²⁺ and Cu²⁺) and a zirconium metal–organic framework (UiO-66-NH₂) was explored using dynamic nuclear polarization-enhanced ¹⁵N{¹H} CPMAS NMR spectroscopy supported by X-ray absorption spectroscopy and density functional calculations. The combined experimental results conclude that each Pt²⁺ coordinates with two NH₂ groups from the MOF and two Cl⁻ from the metal precursor, whereas Cu²⁺ do not form chemical bonds with the NH₂ groups of the MOF framework. Density functional calculations reveal that Pt²⁺ prefers a square-planar structure with the four ligands and resides in the octahedral cage of the MOF in either cis or trans configurations.

  10. Selective Host-Guest Interaction between Metal Ions and Metal-Organic Frameworks using Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy

    SciTech Connect

    Guo, Zhiyong; Kobayashi, Takeshi; Wang, Lin-Lin; Goh, Tian Wei; Xiao, Chaoxian; Caporini, Marc A; Rosay, Melanie; Johnson, Duane D; Pruski, Marek; Huang, Wenyu

    2014-10-08

    The host–guest interaction between metal ions (Pt2+ and Cu2+) and a zirconium metal–organic framework (UiO-66-NH2) was explored using dynamic nuclear polarization-enhanced 15N{1H} CPMAS NMR spectroscopy supported by X-ray absorption spectroscopy and density functional calculations. The combined experimental results conclude that each Pt2+ coordinates with two NH2 groups from the MOF and two Cl- from the metal precursor, whereas Cu2+ do not form chemical bonds with the NH2 groups of the MOF framework. Density functional calculations reveal that Pt2+ prefers a square-planar structure with the four ligands and resides in the octahedral cage of the MOF in either cis or trans configurations.

  11. Novel enhancement of thin-form-factor galvanic cells: Probing halogenated organic oxidizers and metal anodes

    NASA Astrophysics Data System (ADS)

    Cardenas-Valencia, Andres M.; Adornato, Lori; Short, R. Timothy; Langebrake, Larry

    The work reported herein demonstrates a novel method to improve the overall performance of thin-form-factor galvanic cells, fabricated via micro-electromechanical systems (MEMS) processes. Use of solid, low cost, cyclic-halogenated, organic catholyte materials permits water activation of cells consisting of metal anode and catalytic platinum positive electrodes. Similar cells, employing aluminum and zinc anodes, have been activated using sodium hypochlorite (NaClO) solutions, i.e. bleach, in the past. The oxidizers chosen for this study (bromo-, chloro- and iodo-succinimides, and sodium dichloroisocyanuric acid) supply the cathode's oxy-halogenated ions when in contact with water. Zinc, magnesium and aluminum anodes are utilized to fabricate galvanic cells. A comparison between these anodes, coupled with various oxidizers, is included herein. Results using aluminum anode cells show that, even though the utilization efficiency of the catholyte reagents is low (faradic efficiencies between 16 and 19%), the performance of the new water-activated cells (6 cm × 6 cm × 0.25 cm) is superior when compared to those activated with bleach. For instance, operational lives of 6 h (activation with 10% NaClO solution) increase to more than 30 h using the new approach, with a 100-ohm-load. It is also shown that specific energies of 90-110 Wh kg -1 (calculated to include both reagent and packaging mass) could be obtained using the described approach with current draws between 10 and 20 mA. The specific energies obtained suggest that novel MEMS-type cells could have much broader application than low-current, bleach-activated cells.

  12. Toward interfacing organic semiconductors with ferromagnetic transition metal substrates: enhanced stability via carboxylate anchoring.

    PubMed

    Han, R; Blobner, F; Bauer, J; Duncan, D A; Barth, J V; Feulner, P; Allegretti, F

    2016-07-28

    We demonstrate that chemically well-defined aromatic self-assembled monolayers (SAMs) bonded via a carboxylate head group to surfaces of ferromagnetic (FM = Co, Ni, Fe) transition metals can be prepared at ambient temperature in ultra-high vacuum and are thermally stable up to 350-400 K (depending on the metal). The much superior stability over thiolate-bonded SAMs, which readily decompose above 200 K, and the excellent electronic communication guaranteed by the carboxylate bonding render benzoate/FM-metal interfaces promising candidates for application in spintronics.

  13. Enhanced CO oxidation on CeO2/Co3O4 nanojunctions derived from annealing of metal organic frameworks.

    PubMed

    Wang, Changlai; Wang, Dongdong; Yang, Yang; Li, Ren; Chen, Changle; Chen, Qianwang

    2016-12-01

    The interface of nanojunctions plays an important role in the performance of heterogeneous catalysts. However, it is highly challenging to construct nanojunctions which are usually prepared by complex multistep processes. Metal-organic frameworks (MOFs), with designable metal centers and tunable organic ligands, are promising precursors for the one-step synthesis of nanojunctions. Herein, we prepared porous CeO2/Co3O4 nanojunctions by direct annealing of MOFs in air. These unique nanojunctions exhibit remarkable catalytic activity for CO oxidation, which can achieve complete oxidization of CO to CO2 at 110 °C. In contrast, the temperature required for 100% CO oxidation is 190 °C for pure Co3O4. Moreover, the nanojunctions can maintain complete CO conversion after 16 h at 110 °C. Density functional theory calculations revealed that the enhancement in the catalytic activity of CeO2/Co3O4 nanojunctions can be attributed to the charge transfer through the interfaces of the nanojunctions.

  14. Metal Oxide Assisted Preparation of Core-Shell Beads with Dense Metal-Organic Framework Coatings for the Enhanced Extraction of Organic Pollutants.

    PubMed

    Del Rio, Mateo; Palomino Cabello, Carlos; Gonzalez, Veronica; Maya, Fernando; Parra, Jose B; Cerdà, Victor; Turnes Palomino, Gemma

    2016-08-08

    Dense and homogeneous metal-organic framework (MOF) coatings on functional bead surfaces are easily prepared by using intermediate sacrificial metal oxide coatings containing the metal precursor of the MOF. Polystyrene (PS) beads are coated with a ZnO layer to give ZnO@PS core-shell beads. The ZnO@PS beads are reactive in the presence of 2-methylimidazole to transform part of the ZnO coating into a porous zeolitic imidazolate framework-8 (ZIF-8) external shell positioned above the internal ZnO precursor shell. The obtained ZIF-8@ZnO@PS beads can be easily packed in column format for flow-through applications, such as the solid-phase extraction of trace priority-listed environmental pollutants. The prepared material shows an excellent permeance to flow when packed as a column to give high enrichment factors, facile regeneration, and excellent reusability for the extraction of the pollutant bisphenol A. It also shows an outstanding performance for the simultaneous enrichment of mixtures of endocrine disrupting chemicals (bisphenol A, 4-tert-octylphenol and 4-n-nonylphenol), facilitating their analysis when present at very low levels (<1 μg L(-1) ) in drinking waters. For the extraction of the pollutant bisphenol A, the prepared ZIF-8@ZnO@PS beads also show a superior extraction and preconcentration capacity to that of the PS beads used as precursors and the composite materials obtained by the direct growth of ZIF-8 on the surface of the PS beads in the absence of metal oxide intermediate coatings.

  15. Enhanced photovoltaic performance of Cu-based metal-organic frameworks sensitized solar cell by addition of carbon nanotubes

    PubMed Central

    Lee, Deok Yeon; Shin, Chan Yong; Yoon, Seog Joon; Lee, Haw Young; Lee, Wonjoo; Shrestha, Nabeen K.; Lee, Joong Kee; Han, Sung-Hwan

    2014-01-01

    In the present work, TiO2 nanoparticle and multi-walled carbon nanotubes composite powder is prepared hydrothermally. After doctor blading the paste from composite powder, the resulted composite film is sensitized with Cu-based metal-organic frameworks using a layer-by-layer deposition technique and the film is characterized using FE-SEM, EDX, XRD, UV/Visible spectrophotometry and photoluminescence spectroscopy. The influence of the carbon nanotubes in photovoltaic performance is studied by constructing a Grätzel cell with I3−/I− redox couple containing electrolyte. The results demonstrate that the introduction of carbon nanotubes accelerates the electron transfer, and thereby enhances the photovoltaic performance of the cell with a nearly 60% increment in power conversion efficiency. PMID:24488110

  16. Rigidifying Fluorescent Linkers by Metal-Organic Framework Formation for Fluorescence Blue Shift and Quantum Yield Enhancement

    SciTech Connect

    Wei, ZW; Gu, ZY; Arvapally, RK; Chen, YP; McDougald, RN; Ivy, JF; Yakovenko, AA; Feng, DW; Omary, MA; Zhou, HC

    2014-06-11

    We demonstrate that rigidifying the structure of fluorescent linkers by structurally constraining them in metal-organic frameworks (MOFs) to control their conformation effectively tunes the fluorescence energy and enhances the quantum yield. Thus, a new tetraphenylethylene-based zirconium MOF exhibits a deep-blue fluorescent emission at 470 nm with a unity quantum yield (99.9 +/- 0.5%) under Ar, representing ca. 3600 cm(-1) blue shift and doubled radiative decay efficiency vs the linker precursor. An anomalous increase in the fluorescence lifetime and relative intensity takes place upon heating the solid MOF from cryogenic to ambient temperatures. The origin of these unusual photoluminescence properties is attributed to twisted linker conformation, intramolecular hindrance, and framework rigidity.

  17. Enhanced anti-cancer activities of a gold(III) pyrrolidinedithiocarbamato complex incorporated in a biodegradable metal-organic framework.

    PubMed

    Sun, Raymond Wai-Yin; Zhang, Ming; Li, Dan; Li, Mian; Wong, Alice Sze-Tsai

    2016-10-01

    An anti-cancer active gold(III) pyrrolidinedithiocarbamato complex [(PDTC)Au(III)Cl2] (1) has been synthesized and characterized by means of X-ray crystallography. Compared to the pyrrolidinedithiocarbamate ligand itself, this gold(III) complex displays an up to 33-fold higher anti-cancer potency towards a panel of cancer cell lines including the cisplatin-resistant ovarian carcinoma cell line (A2780cis). As demonstrated by a set of Transwell® assay-based cytotoxicity experiments, incorporating this gold(III) complex in a zinc-based biodegradable metal-organic framework (MOF) displays a significant enhancement in anti-cancer activity towards A2780cis than the gold(III) complex alone. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Metal-Organic Framework Supported on Processable Polymer Matrix by In Situ Copolymerization for Enhanced Iron(III) Detection.

    PubMed

    Liu, Chun-Sen; Chen, Min; Tian, Jia-Yue; Wang, Lei; Li, Min; Fang, Shao-Ming; Wang, Xi; Zhou, Li-Ming; Wang, Zhuo-Wei; Du, Miao

    2017-03-17

    Metal-organic frameworks (MOFs) represent a promising class of porous materials. However, MOFs show poor processability that impedes their full potential in applications. This work develops a composite strategy to skillfully load MOFs on a polymer plate to afford processability for these powder materials. A predesigned mesoporous MOF with active -NH2 groups around the pore walls was prepared and its copolymerization with the -NCO groups of macromonomers (polyurethane acrylate) could be facilely induced by an initiator under mild conditions. Notably, the target MOF-polymer composite is transparent, elastic, and shows enhanced Fe(3+) detection compared with that of the individual MOF functional component. This result can be ascribed to the synergistic effect of the composite with newly formed chemical bonds between the MOF particle and polymer matrix. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Strategies for Enhancing the Catalytic Performance of Metal-Organic Frameworks in the Fixation of CO2 into Cyclic Carbonates.

    PubMed

    Taherimehr, Masoumeh; Van de Voorde, Ben; Wee, Lik H; Martens, Johan A; De Vos, Dirk E; Pescarmona, Paolo P

    2017-03-22

    Metal-organic frameworks (MOFs) with accessible Lewis acid sites are finding increasing application in the field of heterogeneous catalysis. However, the structural instability of MOFs when they are exposed to high temperature and/or high pressure often limits their applicability. In this study, two strategies were applied to achieve a MOF catalyst with high stability, activity and selectivity in the reaction of CO2 with styrene oxide to produce styrene carbonate. In the first approach, a MOF with linkers with high connectivity as MIL-100(Cr) was studied, leading to promising activity and recyclability in consecutive catalytic runs without loss of activity. In the second strategy, a MOF with linkers with lower connectivity but with encapsulated Keggin phosphotungstic acid (MIL-101(Cr)[PTA]) was prepared. However, the activity of this catalyst decreased upon reuse as a consequence of deterioration of the MOF. Further investigations were dedicated to the enhancement of the catalytic performance of MIL-100 and included the variation of the metal centre as well as the type and loading of organic salt acting as nucleophile source. This allowed tuning the nature of the organic halide to the specific porous structure of MIL-100(Cr) to prevent diffusion limitations. The best catalytic performance was obtained for MIL-100(Cr) in combination with EMIMBr ionic liquid, which gave very high styrene carbonate yield (94 %) with complete selectivity after 18 h of reaction at mild temperature (60 °C). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Three-Dimensional Hierarchical Architectures Derived from Surface-Mounted Metal-Organic Framework Membranes for Enhanced Electrocatalysis.

    PubMed

    Jia, Gan; Zhang, Wen; Fan, Guozheng; Li, Zhaosheng; Fu, Degang; Hao, Weichang; Yuan, Chunwei; Zou, Zhigang

    2017-09-04

    Inspired by the rapid development of metal-organic-framework-derived materials in various applications, a facile synthetic strategy was developed for fabrication of 3D hierarchical nanoarchitectures. A surface-mounted metal-organic framework membrane was pyrolyzed at a range of temperatures to produce catalysts with excellent trifunctional electrocatalytic efficiencies for the oxygen reduction, hydrogen evolution, and oxygen evolution reactions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Plasmonic core-shell metal-organic nanoparticles enhanced dye-sensitized solar cells.

    PubMed

    Xu, Qi; Liu, Fang; Meng, Weisi; Huang, Yidong

    2012-11-05

    We present an investigation on introducing core-shell Au@PVP nanoparticles (NPs) into dye-sensitized solar cells. As a novel core-shell NPs structure, Au@PVP present not only the chemical stability to iodide/triiodide electrolyte, but also the adhesiveness to dye molecules, which could help to localize most of dye molecules around plasmonic NPs, hence increasing the optical absorption consequently the power conversion efficiency (PCE) of the device. We obtain a PCE enhancement of 30% from 3.3% to 4.3% with incorporation of Au@PVP NPs. Moreover, the device performance with different concentration of Au@PVP NPs from 0 to 12.5 wt% has been studied, and we draw the conclusion that the performance of DSCs could be well improved through enhancing the light absorption by local surface plasmon (LSP) effect from Au@PVP NPs with an optimized concentration.

  2. Enhanced H2 uptake in solvents confined in mesoporous metal-organic framework.

    PubMed

    Clauzier, Stephanie; Ho, Linh Ngoc; Pera-Titus, Marc; Coasne, Benoit; Farrusseng, David

    2012-10-24

    Hydrogen uptake at 298 K and 30 bar in hybrid sorbents consisting of n-hexane confined in MIL-101 is found to be 22 times larger than in sole n-hexane. The enhanced solubility in MIL-101, found to be 3 times larger than in mesoporous silica of similar pore size, highlights the key roles played by surface chemistry and accessible surface area.

  3. Enhancing gas adsorption and separation capacity through ligand functionalization of microporous metal-organic framework structures.

    PubMed

    Zhao, Yonggang; Wu, Haohan; Emge, Thomas J; Gong, Qihan; Nijem, Nour; Chabal, Yves J; Kong, Lingzhu; Langreth, David C; Liu, Hui; Zeng, Heping; Li, Jing

    2011-04-26

    Hydroxyl- and amino- functionalized [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O leads to two new structures, [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O (BDC=terephthalic acid, TED=triethylenediamine, BDC-OH=2-hydroxylterephthalic acid, BDC-NH(2)=2-aminoterephthalic acid). Single-crystal X-ray diffraction and powder X-ray diffraction studies confirmed that the structures of both functionalized compounds are very similar to that of their parent structure. Compound [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O can be considered a 3D porous structure with three interlacing 1D channels, whereas both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O contain only 1D open channels as a result of functionalization of the BDC ligand by the OH and NH(2) groups. A notable decrease in surface area and pore size is thus observed in both compounds. Consequently, [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O takes up the highest amount of H(2) at low temperatures. Interestingly, however, both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O show significant enhancement in CO(2) uptake at room temperature, suggesting that the strong interactions between CO(2) and the functionalized ligands, indicating that surface chemistry, rather than porosity, plays a more important role in CO(2) adsorption. A comparison of single-component CO(2), CH(4), CO, N(2), and O(2) adsorption isotherms demonstrates that the adsorption selectivity of CO(2) over other small gases is considerably enhanced through functionalization of the frameworks. Infrared absorption spectroscopic measurements and theoretical calculations are also carried out to assess the effect of functional groups on CO(2) and H(2) adsorption potentials.

  4. Enhanced Photochemical Hydrogen Production by a Molecular Diiron Catalyst Incorporated into a Metal-Organic Framework

    SciTech Connect

    Pullen, Sonja; Fei, Honghan; Orthaber, Andreas; Cohen, Seth M.; Ott, Sascha

    2013-12-04

    A molecular proton reduction catalyst [FeFe](dcbdt)(CO)6 (1, dcbdt = 1,4-dicarboxylbenzene-2,3-dithiolate) with structural similarities to [FeFe]-hydrogenase active sites has been incorporated into a highly robust Zr(IV)-based metal–organic framework (MOF) by postsynthetic exchange (PSE). The PSE protocol is crucial as direct solvothermal synthesis fails to produce the functionalized MOF. The molecular integrity of the organometallic site within the MOF is demonstrated by a variety of techniques, including X-ray absorption spectroscopy. In conjunction with [Ru(bpy)3]2+ as a photosensitizer and ascorbate as an electron donor, MOF-[FeFe](dcbdt)(CO)6 catalyzes photochemical hydrogen evolution in water at pH 5. The immobilized catalyst shows substantially improved initial rates and overall hydrogen production when compared to a reference system of complex 1 in solution. Improved catalytic performance is ascribed to structural stabilization of the complex when incorporated in the MOF as well as the protection of reduced catalysts 1 and 12– from undesirable charge recombination with oxidized ascorbate.

  5. Comparison of the ability of organic acids and EDTA to enhance the phytoextraction of metals from a multi-metal contaminated soil.

    PubMed

    Kim, Sung-Hyun; Lee, In-Sook

    2010-02-01

    Chelates have been shown to enhance the phytoextraction of metal from contaminated soil. In this study, we evaluated the ability of chelates to enhance the phytoextraction of metals by barnyard grass (Echinochloa crus-galli) from soils contaminated with multiple metals. The results revealed that EDTA increased the ability of barnyard grass to take up Cd, Cu and Pb, but that it resulted in increased soil leaching. Conversely, citric acid induced the removal of Cd, Cu and Pb from soil without increasing the risk of leaching. Furthermore, E.crus-galli showed no signs of phytotoxicity in response to treatment with citric acid, whereas its shoot growth decreased in response to treatment with EDTA (p < 0.05). Taken together, these results demonstrate that citric acid is a good agent for the enhancement of the phytoextraction of metals.

  6. Encapsulation of curcumin in cyclodextrin-metal organic frameworks: Dissociation of loaded CD-MOFs enhances stability of curcumin.

    PubMed

    Moussa, Zeinab; Hmadeh, Mohamad; Abiad, Mohamad G; Dib, Omar H; Patra, Digambara

    2016-12-01

    Curcumin has been successfully encapsulated in cyclodextrin-metal organic frameworks (CD-MOFs) without altering their crystallinity. The interaction between curcumin and CD-MOFs is strong through hydrogen bond type interaction between the OH group of cyclodextrin of CD-MOFs and the phenolic hydroxyl group of the curcumin. Interestingly, dissolving the curcumin loaded CD-MOFs crystals in water results in formation of a unique complex between curcumin, γCD and potassium cations. In fact, the initial interaction between curcumin and CD-MOF is crucial for the formation of the latter. This new complex formed in alkaline media at pH 11.5 has maximum absorbance at 520nm and emittance at 600nm. Most importantly, the stability of curcumin in this complex was enhanced by at least 3 orders of magnitude compared to free curcumin and curcumin:γ-CD at pH 11.5. These results suggest a promising benign system of CD-MOFs, which can be used to store and stabilize curcumin for food applications.

  7. Toward Metal-Organic Framework-Based Solar Cells: Enhancing Directional Exciton Transport by Collapsing Three-Dimensional Film Structures.

    PubMed

    Goswami, Subhadip; Ma, Lin; Martinson, Alex B F; Wasielewski, Michael R; Farha, Omar K; Hupp, Joseph T

    2016-11-16

    Owing to their ability to act as light-harvesting scaffolds, porphyrin-containing metal-organic frameworks (MOFs) are in the forefront of research on the application of highly ordered molecular materials to problems in solar-energy conversion. In this work, solvent-assisted linker exchange (SALE) is performed on a pillared paddlewheel porphyrin containing MOF thin film to collapse a 3D framework to a 2D framework. The change in dimensionality of the framework is confirmed by a decrease in the film thickness, the magnitude of which is in agreement with crystallographic parameters for related bulk materials. Furthermore, NMR spectroscopy performed on the digested sample suggests a similar change in geometry is achieved in bulk MOF samples. The decreased distance between the porphyrin chromophores in the 2D MOF film compared to the 3D film results in enhanced energy transfer through the film. The extent of energy transport was probed by assembling MOF thin film where the outermost layers are palladium porphyrin (P2) units, which act as energy traps and fluorescence quenchers. Steady-state emission spectroscopy together with time-resolved emission spectroscopy indicates that excitons can travel through about 9-11 layers (porphyrin layers) in 2D films, whereas in 3D films energy transfer occurs through no more than about 6-8 layers. The results are difficult to understand if only changes in MOF interlayer spacing are considered but become much more understandable if dipole-dipole coupling distances are considered.

  8. Introduction of functionality, selection of topology, and enhancement of gas adsorption in multivariate metal-organic framework-177.

    PubMed

    Zhang, Yue-Biao; Furukawa, Hiroyasu; Ko, Nakeun; Nie, Weixuan; Park, Hye Jeong; Okajima, Satoshi; Cordova, Kyle E; Deng, Hexiang; Kim, Jaheon; Yaghi, Omar M

    2015-02-25

    Metal-organic framework-177 (MOF-177) is one of the most porous materials whose structure is composed of octahedral Zn4O(-COO)6 and triangular 1,3,5-benzenetribenzoate (BTB) units to make a three-dimensional extended network based on the qom topology. This topology violates a long-standing thesis where highly symmetric building units are expected to yield highly symmetric networks. In the case of octahedron and triangle combinations, MOFs based on pyrite (pyr) and rutile (rtl) nets were expected instead of qom. In this study, we have made 24 MOF-177 structures with different functional groups on the triangular BTB linker, having one or more functionalities. We find that the position of the functional groups on the BTB unit allows the selection for a specific net (qom, pyr, and rtl), and that mixing of functionalities (-H, -NH2, and -C4H4) is an important strategy for the incorporation of a specific functionality (-NO2) into MOF-177 where otherwise incorporation of such functionality would be difficult. Such mixing of functionalities to make multivariate MOF-177 structures leads to enhancement of hydrogen uptake by 25%.

  9. Preparation of hydrophobic metal-organic frameworks via plasma enhanced chemical vapor deposition of perfluoroalkanes for the removal of ammonia.

    PubMed

    DeCoste, Jared B; Peterson, Gregory W

    2013-10-10

    Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m(2)/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

  10. Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

    PubMed Central

    DeCoste, Jared B.; Peterson, Gregory W.

    2013-01-01

    Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials. PMID:24145623

  11. Metal-Organic-Compound-Modified MoS2 with Enhanced Solubility for High-Performance Perovskite Solar Cells.

    PubMed

    Dai, Ruina; Wang, Yangyang; Wang, Jie; Deng, Xianyu

    2017-07-21

    MoS2 as a graphene-like 2 D material shows a large potential to replace and even overcome graphene in various important applications owing to its ideal properties of electrical, optical, frictional, and tunable band gap. However, its low solubility in the most of common solvents makes it difficult to prepare by a simple solution process. Here, we introduce a metal-organic compound to modify MoS2 . Phenyl acetylene silver (PAS)-functionalized MoS2 is easily dispersed in solvents like DMF and water. A conductive polymer PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) blend with the MoS2 leads to a significant enhancement of the performance of planar heterojunction perovskite solar cells. The solar cells have a high power conversion efficiency of 16.47 % as well as largely increased stability. This provides a feasible method for large-scale production of MoS2 for wide applications in various electric devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Forming heterojunction: an effective strategy to enhance the photocatalytic efficiency of a new metal-free organic photocatalyst for water splitting.

    PubMed

    Li, Hengshuai; Hu, Haiquan; Bao, Chunjiang; Guo, Feng; Zhang, Xiaoming; Liu, Xiaobiao; Hua, Juan; Tan, Jie; Wang, Aizhu; Zhou, Hongcai; Yang, Bo; Qu, Yuanyuan; Liu, Xiangdong

    2016-07-29

    Photocatalytic water splitting is a new technology for the conversion and utilization of solar energy and has a potential prospect. One important aspect of enhancing the photocatalytic efficiency is how to improve the electron-hole separation. Up to now, there is still no ideal strategy to improve the electron-hole separation. In this article, for metal-free organic photocatalysts, we propose a good strategy- forming heterojunction, which can effectively improve the electron-hole separation. We provide a metal-free organic photocatalyst g-C12N7H3 for water splitting. The stability of g-C12N7H3 has been investigated, the X-ray diffraction spectra has been simulated. Using first-principles calculations, we have systematically studied the electronic structure, band edge alignment, and optical properties for the g-C12N7H3. The results demonstrated that g-C12N7H3 is a new organocatalyst material for water splitting. In order to enhance the photocatalytic efficiency, we provided four strategies, i.e., multilayer stacking, raising N atoms, forming g-C9N10/g-C12N7H3 heterojunction, and forming graphene/g-C12N7H3 heterojunction. Our research is expected to stimulate experimentalists to further study novel 2D metal-free organic materials as visible light photocatalysts. Our strategies, especially forming heterojunction, will substantially help to enhance the photocatalytic efficiency of metal-free organic photocatalyst.

  13. Synergistic concurrent enhancement of charge generation, dissociation, and transport in organic solar cells with plasmonic metal-carbon nanotube hybrids.

    PubMed

    Lee, Ju Min; Lim, Joonwon; Lee, Nayeun; Park, Hyung Il; Lee, Kyung Eun; Jeon, Taewoo; Nam, Soo Ah; Kim, Jehan; Shin, Jonghwa; Kim, Sang Ouk

    2015-03-04

    Plasmonic nanostructures are synthesized by decorating B- or N-doped carbon nanotubes (CNTs) with Au nanoparticles. While the plasmonic nanoparticles promote exciton generation and dissociation, the B- and N-doped CNTs enable charge-selective transport enhancement in the organic active layer. Such concurrent enhancements of all the principal energy-harvesting steps improve the device efficiency up to 9.98% for organic single-junction solar cells.

  14. A metal-organic framework/α-alumina composite with a novel geometry for enhanced adsorptive separation.

    PubMed

    Wang, Chenghong; Lee, Melanie; Liu, Xinlei; Wang, Bo; Paul Chen, J; Li, Kang

    2016-07-07

    The development of a metal-organic framework/α-alumina composite leads to a novel concept: efficient adsorption occurs within a plurality of radial micro-channels with no loss of the active adsorbents during the process. This composite can effectively remediate arsenic contaminated water producing potable water recovery, whereas the conventional fixed bed requires eight times the amount of active adsorbents to achieve a similar performance.

  15. Forming heterojunction: an effective strategy to enhance the photocatalytic efficiency of a new metal-free organic photocatalyst for water splitting

    PubMed Central

    Li, Hengshuai; Hu, Haiquan; Bao, Chunjiang; Guo, Feng; Zhang, Xiaoming; Liu, Xiaobiao; Hua, Juan; Tan, Jie; Wang, Aizhu; Zhou, Hongcai; Yang, Bo; Qu, Yuanyuan; Liu, Xiangdong

    2016-01-01

    Photocatalytic water splitting is a new technology for the conversion and utilization of solar energy and has a potential prospect. One important aspect of enhancing the photocatalytic efficiency is how to improve the electron-hole separation. Up to now, there is still no ideal strategy to improve the electron-hole separation. In this article, for metal-free organic photocatalysts, we propose a good strategy- forming heterojunction, which can effectively improve the electron-hole separation. We provide a metal-free organic photocatalyst g-C12N7H3 for water splitting. The stability of g-C12N7H3 has been investigated, the X-ray diffraction spectra has been simulated. Using first-principles calculations, we have systematically studied the electronic structure, band edge alignment, and optical properties for the g-C12N7H3. The results demonstrated that g-C12N7H3 is a new organocatalyst material for water splitting. In order to enhance the photocatalytic efficiency, we provided four strategies, i.e., multilayer stacking, raising N atoms, forming g-C9N10/g-C12N7H3 heterojunction, and forming graphene/g-C12N7H3 heterojunction. Our research is expected to stimulate experimentalists to further study novel 2D metal-free organic materials as visible light photocatalysts. Our strategies, especially forming heterojunction, will substantially help to enhance the photocatalytic efficiency of metal-free organic photocatalyst. PMID:27470223

  16. Enhanced recovery of valuable metals from spent lithium-ion batteries through optimization of organic acids produced by Aspergillus niger.

    PubMed

    Bahaloo-Horeh, Nazanin; Mousavi, Seyyed Mohammad

    2017-02-01

    In the present study, spent medium bioleaching method was performed using organic acids produced by Aspergillus niger to dissolve Ni, Co, Mn, Li, Cu and Al from spent lithium-ion batteries (LIBs). Response surface methodology was used to investigate the effects and interactions between the effective factors of sucrose concentration, initial pH, and inoculum size to optimize organic acid production. Maximum citric acid, malic acid, and gluconic acid concentrations of 26,478, 1832.53 and 8433.76ppm, respectively, and a minimum oxalic acid concentration of 305.558ppm were obtained under optimal conditions of 116.90 (gl(-1)) sucrose concentration, 3.45% (vv(-1)) inoculum size, and a pH value of 5.44. Biogenically-produced organic acids are used for leaching of spent LIBs at different pulp densities. The highest metal recovery of 100% Cu, 100% Li, 77% Mn, and 75% Al occurred at 2% (wv(-1)) pulp density; 64% Co and 54% Ni recovery occurred at 1% (wv(-1)) pulp density. The bioleaching of metals from spent LIBs can decrease the environmental impact of this waste. The results of this study suggest that the process can be used for large scale industrial purposes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Self-organized colloidal quantum dots and metal nanoparticles for plasmon-enhanced intermediate-band solar cells

    NASA Astrophysics Data System (ADS)

    Mendes, Manuel J.; Hernández, Estela; López, Esther; García-Linares, Pablo; Ramiro, Iñigo; Artacho, Irene; Antolín, Elisa; Tobías, Ignacio; Martí, Antonio; Luque, Antonio

    2013-08-01

    A colloidal deposition technique is presented to construct long-range ordered hybrid arrays of self-assembled quantum dots and metal nanoparticles. Quantum dots are promising for novel opto-electronic devices but, in most cases, their optical transitions of interest lack sufficient light absorption to provide a significant impact in their implementation. A potential solution is to couple the dots with localized plasmons in metal nanoparticles. The extreme confinement of light in the near-field produced by the nanoparticles can potentially boost the absorption in the quantum dots by up to two orders of magnitude. In this work, light extinction measurements are employed to probe the plasmon resonance of spherical gold nanoparticles in lead sulfide colloidal quantum dots and amorphous silicon thin-films. Mie theory computations are used to analyze the experimental results and determine the absorption enhancement that can be generated by the highly intense near-field produced in the vicinity of the gold nanoparticles at their surface plasmon resonance. The results presented here are of interest for the development of plasmon-enhanced colloidal nanostructured photovoltaic materials, such as colloidal quantum dot intermediate-band solar cells.

  18. Self-organized colloidal quantum dots and metal nanoparticles for plasmon-enhanced intermediate-band solar cells.

    PubMed

    Mendes, Manuel J; Hernández, Estela; López, Esther; García-Linares, Pablo; Ramiro, Iñigo; Artacho, Irene; Antolín, Elisa; Tobías, Ignacio; Martí, Antonio; Luque, Antonio

    2013-08-30

    A colloidal deposition technique is presented to construct long-range ordered hybrid arrays of self-assembled quantum dots and metal nanoparticles. Quantum dots are promising for novel opto-electronic devices but, in most cases, their optical transitions of interest lack sufficient light absorption to provide a significant impact in their implementation. A potential solution is to couple the dots with localized plasmons in metal nanoparticles. The extreme confinement of light in the near-field produced by the nanoparticles can potentially boost the absorption in the quantum dots by up to two orders of magnitude.In this work, light extinction measurements are employed to probe the plasmon resonance of spherical gold nanoparticles in lead sulfide colloidal quantum dots and amorphous silicon thin-films. Mie theory computations are used to analyze the experimental results and determine the absorption enhancement that can be generated by the highly intense near-field produced in the vicinity of the gold nanoparticles at their surface plasmon resonance.The results presented here are of interest for the development of plasmon-enhanced colloidal nanostructured photovoltaic materials, such as colloidal quantum dot intermediate-band solar cells.

  19. Organic Superconductor, Made without Metals.

    ERIC Educational Resources Information Center

    Science News, 1980

    1980-01-01

    The discovery of a superconducting organic compound is reported. The compound, (TMTSF)-2, has no metal in its composition, and the author believes that it is the precursor of a family of superconducting organics. (Author/SA)

  20. Organic Superconductor, Made without Metals.

    ERIC Educational Resources Information Center

    Science News, 1980

    1980-01-01

    The discovery of a superconducting organic compound is reported. The compound, (TMTSF)-2, has no metal in its composition, and the author believes that it is the precursor of a family of superconducting organics. (Author/SA)

  1. Carbon-coated rutile titanium dioxide derived from titanium-metal organic framework with enhanced sodium storage behavior

    NASA Astrophysics Data System (ADS)

    Zou, Guoqiang; Chen, Jun; Zhang, Yan; Wang, Chao; Huang, Zhaodong; Li, Simin; Liao, Hanxiao; Wang, Jufeng; Ji, Xiaobo

    2016-09-01

    Carbon-coated rutile titanium dioxide (CRT) was fabricated through an in-situ pyrolysis of titanium-based metal organic framework (Ti8O8(OH)4[O2CC6H4CO2]6) crystals. Benefiting from the Tisbnd Osbnd C skeleton structure of titanium-based metal organic framework, the CRT possesses abundant channels and micro/mesopores with the diameters ranging from 1.06 to 4.14 nm, shows larger specific surface area (245 m2 g-1) and better electronic conductivity compared with pure titanium dioxide (12.8 m2 g-1). When applied as anode material for sodium-ion batteries, the CRT electrode exhibits a high cycling performance with a reversible capacity of ∼175 mAh g-1 at 0.5 C-rate after 200 cycles, and obtains an excellent rate capability of ∼70 mAh g-1 after 2000 cycles even at a specific current of 3360 mA g-1(20 C-rate). The outstanding rate capability can be attributed to the carbon-coated structure, which may effectively prevent aggregation of the titanium dioxide nanoparticles, accelerate the mass transfer of Na+ and speed up the charge transfer rate. Considering these advantages of this particular framework structure, the CRT can serve as an alternative anode material for the industrial application of SIBs.

  2. Removal of organic matter and heavy metals of low concentration from wastewater via micellar-enhanced ultrafiltration: an overview

    NASA Astrophysics Data System (ADS)

    Li, F.; Li, X.; Zhang, J. D.; Peng, L.; Liu, C. Y.

    2017-01-01

    As a new and effective means of wastewater treatment, the micellar-enhanced ultrafiltration (MEUF) has been extensively studied. In this paper, MEUF was introduced from the aspects of theory basis, ultrafiltration membranes, and surfactants. Additionally, the latest research achievements in removing organic matter and heavy ions, its application in actual wastewater, and the characterization parameters of MEUF were introduced and summarized. Then, influences and mechanisms of the primary operation parameters, including surfactant concentration, pH, electrolytes, and transmembrane pressure on the performance of the MEUF process were analyzed. Finally, existing problems in the MEUF process were identified and developmental trends were predicted.

  3. Giant increase in the metal-enhanced fluorescence of organic molecules in nanoporous alumina templates and large molecule-specific red/blue-shift of the fluorescence peak.

    PubMed

    Sarkar, S; Kanchibotla, B; Nelson, J D; Edwards, J D; Anderson, J; Tepper, G C; Bandyopadhyay, S

    2014-10-08

    The fluorescence of organic fluorophore molecules is enhanced when they are placed in contact with certain metals (Al, Ag, Cu, Au, etc.) whose surface plasmon waves couple into the radiative modes of the molecules and increase the radiative efficiency. Here, we report a hitherto unknown size dependence of this metal-enhanced fluorescence (MEF) effect in the nanoscale. When the molecules are deposited in nanoporous anodic alumina films with exposed aluminum at the bottom of the pores, they form organic nanowires standing on aluminum nanoparticles whose plasmon waves have much larger amplitudes. This increases the MEF strongly, resulting in several orders of magnitude increase in the fluorescence intensity of the organic fluorophores. The increase in intensity shows an inverse superlinear dependence on nanowire diameter because the nanowires also act as plasmonic "waveguides" that concentrate the plasmons and increase the coupling of the plasmons with the radiative modes of the molecules. Furthermore, if the nanoporous template housing the nanowires has built-in electric fields due to space charges, a strong molecule-specific red- or blue-shift is induced in the fluorescence peak owing to a renormalization of the dipole moment of the molecule. This can be exploited to detect minute amounts of target molecules in a mixture using their optical signature (fluorescence) despite the presence of confounding background signals. It can result in a unique new technology for biosensing and chemical sensing.

  4. Growth of InN films by radical-enhanced metal organic chemical vapor deposition at a low temperature of 200 °C

    NASA Astrophysics Data System (ADS)

    Takai, Shinnosuke; Lu, Yi; Oda, Osamu; Takeda, Keigo; Kondo, Hiroki; Ishikawa, Kenji; Sekine, Makoto; Hori, Masaru

    2017-06-01

    The InN films were deposited on GaN surfaces at a low temperature of 200 °C by radical-enhanced metal organic chemical vapor deposition (REMOCVD). The REMOCVD system can provide N radicals from the plasma of a N2-H2 mixture gas without using ammonia. Two types of GaN substrate, bulk GaN and GaN on Si(111), were used. The growth mode was modeled as a step flow on the basis of surface morphology observation by atomic force microscopy.

  5. Color filters based on enhanced optical transmission of subwavelength-structured metallic film for multicolor organic light-emitting diode display.

    PubMed

    Hu, Xiao; Zhan, Li; Xia, Yuxing

    2008-08-10

    Using metallic film perforated with a subwavelength periodic structure, a novel concept of a color filter for multicolor organic light-emitting diode (OLED) display is proposed. Based on the phase-matching condition for extraordinary optical transmission, three primary color emissions can be obtained by optimizing the structure's periodicity. Two periodic structures, an array of one-dimensional periodic slits and a two-dimensional periodic hole array, are studied using coupled mode theory. Also, the feasibility of applying these structures as color filters is analyzed. The relative intensity at the unwanted wavelength, which is generated by higher resonant transmission, had been calculated to eliminate its effect on the purity of these filters. It is important that this type of color filter simultaneously solves the low emission efficiency problem for OLEDs with the aid of enhanced transmission of metal film.

  6. Synthesis of hierarchical porous carbon monoliths with incorporated metal-organic frameworks for enhancing volumetric based CO₂ capture capability.

    PubMed

    Qian, Dan; Lei, Cheng; Hao, Guang-Ping; Li, Wen-Cui; Lu, An-Hui

    2012-11-01

    This work aims to optimize the structural features of hierarchical porous carbon monolith (HCM) by incorporating the advantages of metal-organic frameworks (MOFs) (Cu₃(BTC)₂) to maximize the volumetric based CO₂ capture capability (CO₂ capacity in cm³ per cm³ adsorbent), which is seriously required for the practical application of CO₂ capture. The monolithic HCM was used as a matrix, in which Cu₃(BTC)₂ was in situ synthesized, to form HCM-Cu₃(BTC)₂ composites by a step-by-step impregnation and crystallization method. The resulted HCM-Cu₃(BTC)₂ composites, which retain the monolithic shape and exhibit unique hybrid structure features of both HCM and Cu₃(BTC)₂, show high CO₂ uptake of 22.7 cm³ cm⁻³ on a volumetric basis. This value is nearly as twice as the uptake of original HCM. The dynamic gas separation measurement of HCM-Cu₃(BTC)₂, using 16% (v/v) CO₂ in N₂ as feedstock, illustrates that CO₂ can be easily separated from N₂ under the ambient conditions and achieves a high separation factor for CO₂ over N₂, ranging from 67 to 100, reflecting a strongly competitive CO₂ adsorption by the composite. A facile CO₂ release can be realized by purging an argon flow through the fixed-bed adsorber at 25 °C, indicating the good regeneration ability.

  7. Removal of organic compounds and trace metals from oil sands process-affected water using zero valent iron enhanced by petroleum coke.

    PubMed

    Pourrezaei, Parastoo; Alpatova, Alla; Khosravi, Kambiz; Drzewicz, Przemysław; Chen, Yuan; Chelme-Ayala, Pamela; Gamal El-Din, Mohamed

    2014-06-15

    The oil production generates large volumes of oil sands process-affected water (OSPW), referring to the water that has been in contact with oil sands or released from tailings deposits. There are concerns about the environmental impacts of the release of OSPW because of its toxicity. Zero valent iron alone (ZVI) and in combination with petroleum coke (CZVI) were investigated as environmentally friendly treatment processes for the removal of naphthenic acids (NAs), acid-extractable fraction (AEF), fluorophore organic compounds, and trace metals from OSPW. While the application of 25 g/L ZVI to OSPW resulted in 58.4% removal of NAs in the presence of oxygen, the addition of 25 g petroleum coke (PC) as an electron conductor enhanced the NAs removal up to 90.9%. The increase in ZVI concentration enhanced the removals of NAs, AEF, and fluorophore compounds from OSPW. It was suggested that the electrons generated from the oxidation of ZVI were transferred to oxygen, resulting in the production of hydroxyl radicals and oxidation of NAs. When OSPW was de-oxygenated, the NAs removal decreased to 17.5% and 65.4% during treatment with ZVI and CZVI, respectively. The removal of metals in ZVI samples was similar to that obtained during CZVI treatment. Although an increase in ZVI concentration did not enhance the removal of metals, their concentrations effectively decreased at all ZVI loadings. The Microtox(®) bioassay with Vibrio fischeri showed a decrease in the toxicity of ZVI- and CZVI-treated OSPW. The results obtained in this study showed that the application of ZVI in combination with PC is a promising technology for OSPW treatment.

  8. Nanoscale metal-organic materials.

    PubMed

    Carné, Arnau; Carbonell, Carlos; Imaz, Inhar; Maspoch, Daniel

    2011-01-01

    Metal-organic materials are found to be a fascinating novel class of functional nanomaterials. The limitless combinations between inorganic and organic building blocks enable researchers to synthesize 0- and 1-D metal-organic discrete nanostructures with varied compositions, morphologies and sizes, fabricate 2-D metal-organic thin films and membranes, and even structure them on surfaces at the nanometre length scale. In this tutorial review, the synthetic methodologies for preparing these miniaturized materials as well as their potential properties and future applications are discussed. This review wants to offer a panoramic view of this embryonic class of nanoscale materials that will be of interest to a cross-section of researchers working in chemistry, physics, medicine, nanotechnology, materials chemistry, etc., in the next years.

  9. "Clickable" metal-organic framework.

    PubMed

    Goto, Yuta; Sato, Hiroki; Shinkai, Seiji; Sada, Kazuki

    2008-11-05

    We demonstrated the metal-organic framework bearing the azide group in the organic linkers and in situ click reactions with some small alkynes. The XRPD patterns indicated that the click reaction proceeded without any decomposition of the original MOF network. Controlling the organic linkers and incorporation of the azide groups should provide the designer-made MOFs that have controlled molecular cavities with the desired steric dimensions and functionality.

  10. Elucidation of transport mechanism and enhanced alkali ion transference numbers in mixed alkali metal-organic ionic molten salts.

    PubMed

    Chen, Fangfang; Forsyth, Maria

    2016-07-28

    Mixed salts of Ionic Liquids (ILs) and alkali metal salts, developed as electrolytes for lithium and sodium batteries, have shown a remarkable ability to facilitate high rate capability for lithium and sodium electrochemical cycling. It has been suggested that this may be due to a high alkali metal ion transference number at concentrations approaching 50 mol% Li(+) or Na(+), relative to lower concentrations. Computational investigations for two IL systems illustrate the formation of extended alkali-anion aggregates as the alkali metal ion concentration increases. This tends to favor the diffusion of alkali metal ions compared with other ionic species in electrolyte solutions; behavior that has recently been reported for Li(+) in a phosphonium ionic liquid, thus an increasing alkali transference number. The mechanism of alkali metal ion diffusion via this extended coordination environment present at high concentrations is explained and compared to the dynamics at lower concentrations. Heterogeneous alkali metal ion dynamics are also evident and, somewhat counter-intuitively, it appears that the faster ions are those that are generally found clustered with the anions. Furthermore these fast alkali metal ions appear to correlate with fastest ionic liquid solvent ions.

  11. Organic metal neutron detector

    DOEpatents

    Butler, M.A.; Ginley, D.S.

    1984-11-21

    A device for detection of neutrons comprises: as an active neutron sensing element, a conductive organic polymer having an electrical conductivity and a cross-section for said neutrons whereby a detectable change in said conductivity is caused by impingement of said neutrons on the conductive organic polymer which is responsive to a property of said polymer which is altered by impingement of said neutrons on the polymer; and means for associating a change in said alterable property with the presence of neutrons at the location of said device.

  12. A simple and powerful co-delivery system based on pH-responsive metal-organic frameworks for enhanced cancer immunotherapy.

    PubMed

    Duan, Fei; Feng, Xiaochen; Yang, Xinjian; Sun, Wentong; Jin, Yi; Liu, Huifang; Ge, Kun; Li, Zhenhua; Zhang, Jinchao

    2017-04-01

    Tumor-associated antigens (TAAs)-loaded nanoparticles are able to be actively internalized by antigen-presenting cells (APCs) and have shown promising potential in cancer immunotherapy. However, current TAAs delivery strategy exhibits limitations of complicated synthesis process, low loading efficiency and inefficient CD8(+) cytotoxic T lymphocyte activation leading to unsatisfactory therapeutic effect. Thus, the construction of novel TAAs-delivery systems for enhanced cancer therapy is highly desirable. In this work, we fabricated a very simple yet powerful antigens-delivery system for cancer immunotherapy based-on pH-responsive metal-organic frameworks (MOFs) with size about 30 nm. TAAs can be loaded into MOFs in the one-pot synthesis process and released with the degradation of MOFs in the acidic environment of endo/lysosome as the result of relatively labile metal-ligand bonds. The endosomolytic nanoparticles would facilitate protein antigens escape from endo/lysosome and optimal for enhancing antigen cross-presentation. Furthermore, the introduction of immunostimulatory unmethylated cytosine-phosphate-guanine oligonucleotide (CpG) through Watson-Crick base pairing would further enhance CD8(+) cytotoxic T lymphocyte responses. We demonstrated that the method to co-delivery antigens and immunostimulatory molecules was very simple, convenient and effective and showed no obvious toxicity both in vitro and in vivo. This method gave a high antigens-loading capacity and the maximal antigen encapsulating efficiency was about 55% (w/w). Additionally, the pH-responsive co-delivery system exerted enhanced antitumor outcome (about 100% survival) in B16-OVA melanoma cancers in vivo. Furthermore, we confirmed that this high rating of therapeutic effect was attributed to the recruitment of tumor-killing immunocyte. This work demonstrates the ability of pH-responsive, endosomolytic MOFs to induce strong cellular immune responses for cancer therapy by co-delivery of CpG ODN

  13. Imparting surface hydrophobicity to metal-organic frameworks using a facile solution-immersion process to enhance water stability for CO2 capture.

    PubMed

    Qian, Xukun; Sun, Fuxing; Sun, Jing; Wu, Hongyu; Xiao, Fei; Wu, Xinxin; Zhu, Guangshan

    2017-02-02

    The water sensitivity of metal-organic frameworks (MOFs) poses a critical issue for their large-scale applications. One effective method to solve this is to provide MOFs with a hydrophobic surface. Herein, we develop a facile solution-immersion process to deposit a hydrophobic coating on the MOFs' external surface without blocking their intrinsic pores. The water contact angle of the surface hydrophobic (SH) MOFs is ∼146°. The hydrophobic coating not only greatly enhances MOFs' water stability but also provides durable protection against the attack of water molecules. When exposed to liquid water, the SH samples well retain their crystal structure, morphology, surface area and CO2 uptake capacity. However, the as-synthesized (AS) samples nearly collapse and lose their porosity as well as CO2 uptake capacity after the same exposure. This study opens up a new avenue for the MOFs' application of gas sorption in the presence of water.

  14. Enhanced isosteric heat of H2 adsorption by inclusion of crown ethers in a porous metal-organic framework.

    PubMed

    Park, Hye Jeong; Suh, Myunghyun Paik

    2012-04-07

    Inclusion of 18-crown-6 or 15-crown-5 in a porous MOF increased the isosteric heats of H(2) adsorption significantly, which are comparable to MOFs containing open metal sites. This journal is © The Royal Society of Chemistry 2012

  15. Controlled Release of Naringin in Metal-Organic Framework-Loaded Mineralized Collagen Coating to Simultaneously Enhance Osseointegration and Antibacterial Activity.

    PubMed

    Yu, Mengfei; You, Dongqi; Zhuang, Junjun; Lin, Suya; Dong, Lingqing; Weng, Shengtao; Zhang, Bin; Cheng, Kui; Weng, Wenjian; Wang, Huiming

    2017-06-14

    Two important goals in orthopedic implant research are to promote osseointegration and prevent infection. However, much previous effort has been focused on the design of coatings to either enhance osseointegration while ignoring antibacterial activity or vice versa, to prevent infection while ignoring bone integration. Here, we designed a multifunctional mineralized collagen coating on titanium with the aid of metal-organic framework (MOF) nanocrystals to control the release of naringin, a Chinese herbal medicine that could promote osseointegration and prevent bacterial infection. The attachment, proliferation, osteogenic differentiation, and mineralization of mesenchymal stem cells on the coating were significantly enhanced. Meanwhile, the antibacterial abilities against Staphylococcus aureus were also promoted. Furthermore, release kinetics analysis indicated that the synergistic effect of a primary burst release stage and secondary slow release stage played a critical role in the performance and could be controlled by the relative concentrations of MOF and naringin. This work thus provides a novel strategy to engineer multifunctional orthopedic coatings that can enhance osseointegration and simultaneously inhibit microbial cell growth.

  16. Metal-doped organic foam

    DOEpatents

    Rinde, James A.

    1982-01-01

    Organic foams having a low density and very small cell size and method for producing same in either a metal-loaded or unloaded (nonmetal loaded) form are described. Metal-doped foams are produced by soaking a polymer gel in an aqueous solution of desired metal salt, soaking the gel successively in a solvent series of decreasing polarity to remove water from the gel and replace it with a solvent of lower polarity with each successive solvent in the series being miscible with the solvents on each side and being saturated with the desired metal salt, and removing the last of the solvents from the gel to produce the desired metal-doped foam having desired density cell size, and metal loading. The unloaded or metal-doped foams can be utilized in a variety of applications requiring low density, small cell size foam. For example, rubidium-doped foam made in accordance with the invention has utility in special applications, such as in x-ray lasers.

  17. Facile in Situ Synthesis of Silver Nanoparticles on the Surface of Metal-Organic Framework for Ultrasensitive Surface-Enhanced Raman Scattering Detection of Dopamine.

    PubMed

    Jiang, Zhongwei; Gao, Pengfei; Yang, Lin; Huang, Chengzhi; Li, Yuanfang

    2015-12-15

    Surface-enhanced Raman scattering (SERS) signals are intensively dominated by the Raman hot spots and distance between analyte molecules and metallic nanostructures. Herein, an efficient SERS substrate was developed by in situ synthesis of silver nanoparticles (AgNPs) on the surface of MIL-101 (Fe), a typical metal-organic framework (MOF). The as-prepared SERS substrate combines the numerous Raman hot spots between the high-density Ag NPs and the excellent adsorption performance of MOFs, making it an excellent SERS substrate for highly sensitive SERS detection by effectively concentrating analytes in close proximity to the Raman hot spots domains between the adjacent AgNPs. The resulting hybrid material was used for ultrasensitive SERS detection of dopamine based on the peroxidase-like activity of MIL-101 (Fe) by utilizing the enzyme-linked immunosorbent assay (ELISA) colorimetric substrate, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as a SERS marker. This new developed method showed good linearity in the range from 1.054 pM to 210.8 nM for dopamine with the correlation coefficient of 0.992, detection limit of approximately 0.32 pM [signal-to-noise ratio (S/N) = 3], and acceptable recoveries ranging from 99.8% to 108.0% in human urine. These results predict that the proposed SERS system may open up a new opportunity for chemical and biological assay applications.

  18. Organically modified silicas on metal nanowires.

    PubMed

    Dean, Stacey L; Stapleton, Joshua J; Keating, Christine D

    2010-09-21

    Organically modified silica coatings were prepared on metal nanowires using a variety of silicon alkoxides with different functional groups (i.e., carboxyl groups, polyethylene oxide, cyano, dihydroimidazole, and hexyl linkers). Organically modified silicas were deposited onto the surface of 6-μm-long, ∼300-nm-wide, cylindrical metal nanowires in suspension by the hydrolysis and polycondensation of silicon alkoxides. Syntheses were performed at several ratios of tetraethoxysilane to an organically modified silicon alkoxide to incorporate desired functional groups into thin organosilica shells on the nanowires. These coatings were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy. All of the organically modified silicas prepared here were sufficiently porous to allow the removal of the metal nanowire cores by acid etching to form organically modified silica nanotubes. Additional functionality provided to the modified silicas as compared to unmodified silica prepared using only tetraethoxysilane precursors was demonstrated by chromate adsorption on imidazole-containing silicas and resistance to protein adsorption on polyethyleneoxide-containing silicas. Organically modified silica coatings on nanowires and other nano- and microparticles have potential application in fields such as biosensing or nanoscale therapeutics due to the enhanced properties of the silica coatings, for example, the prevention of biofouling.

  19. Organically Modified Silicas on Metal Nanowires

    PubMed Central

    2010-01-01

    Organically modified silica coatings were prepared on metal nanowires using a variety of silicon alkoxides with different functional groups (i.e., carboxyl groups, polyethylene oxide, cyano, dihydroimidazole, and hexyl linkers). Organically modified silicas were deposited onto the surface of 6-μm-long, ∼300-nm-wide, cylindrical metal nanowires in suspension by the hydrolysis and polycondensation of silicon alkoxides. Syntheses were performed at several ratios of tetraethoxysilane to an organically modified silicon alkoxide to incorporate desired functional groups into thin organosilica shells on the nanowires. These coatings were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy. All of the organically modified silicas prepared here were sufficiently porous to allow the removal of the metal nanowire cores by acid etching to form organically modified silica nanotubes. Additional functionality provided to the modified silicas as compared to unmodified silica prepared using only tetraethoxysilane precursors was demonstrated by chromate adsorption on imidazole-containing silicas and resistance to protein adsorption on polyethyleneoxide-containing silicas. Organically modified silica coatings on nanowires and other nano- and microparticles have potential application in fields such as biosensing or nanoscale therapeutics due to the enhanced properties of the silica coatings, for example, the prevention of biofouling. PMID:20715881

  20. Tuning the Morphology and Activity of Electrospun Polystyrene/UiO-66-NH2 Metal-Organic Framework Composites to Enhance Chemical Warfare Agent Removal.

    PubMed

    Peterson, Gregory W; Lu, Annie X; Epps, Thomas H

    2017-09-20

    This work investigates the processing-structure-activity relationships that ultimately facilitate the enhanced performance of UiO-66-NH2 metal-organic frameworks (MOFs) in electrospun polystyrene (PS) fibers for chemical warfare agent detoxification. Key electrospinning processing parameters including solvent type (dimethylformamide [DMF]) vs DMF/tetrahydrofuran [THF]), PS weight fraction in solution, and MOF weight fraction relative to PS were varied to optimize MOF incorporation into the fibers and ultimately improve composite performance. It was found that composites spun from pure DMF generally resulted in MOF crystal deposition on the surface of the fibers, while composites spun from DMF/THF typically led to MOF crystal deposition within the fibers. For cases in which the MOF was incorporated on the periphery of the fibers, the composites generally demonstrated better gas uptake (e.g., nitrogen, chlorine) because of enhanced access to the MOF pores. Additionally, increasing both the polymer and MOF weight percentages in the electrospun solutions resulted in larger diameter fibers, with polymer concentration having a more pronounced effect on fiber size; however, these larger fibers were generally less efficient at gas separations. Overall, exploring the electrospinning parameter space resulted in composites that outperformed previously reported materials for the detoxification of the chemical warfare agent, soman. The data and strategies herein thus provide guiding principles applicable to the design of future systems for protection and separations as well as a wide range of environmental remediation applications.

  1. Effectiveness of metal-metal and metal-organic compound combinations against Plutella xylostella: implications for plant elemental defense.

    PubMed

    Jhee, Edward M; Boyd, Robert S; Eubanks, Micky D

    2006-02-01

    Plants that contain elevated foliar metal concentrations can be categorized as accumulators or, if the accumulation is extreme, hyperaccumulators. The defense hypothesis suggests that these plants may be defended against folivore attack, and recent research has indicated that metal concentrations at or below the accumulator range may be defensively effective. This experiment explored the toxicity of four metals hyper-accumulated by plants (Cd, Ni, Pb, and Zn) and asked if combinations of metals, or metals and organic chemicals, might broaden the defensive effectiveness of metals. Metals were used alone and in certain metal + metal (Zn plus Ni, Pb, or Cd) and metal + organic defensive chemical (Ni plus tannic acid, atropine, or nicotine) combinations. Artificial diet amended with these treatments was fed to larvae of the crucifer specialist herbivore Plutella xylostella. Combinations of metals and metals + organic chemicals significantly decreased survival and pupation rates, compared to single treatments, for at least some concentrations in every experiment. Effects of combinations were additive rather than synergistic or antagonistic. Because Zn enhanced the toxicity of other metals and Ni enhanced the toxicity of organic defensive chemicals, our findings suggest that the defensive effects of metals are more widespread among plants than previously believed. They also support the hypothesis that herbivore defense may have led to the evolution of metal hyper-accumulation by increasing the preexisting defensive effects of metals at accumulator levels in plants.

  2. Near-Infrared- and Visible-Light-Enhanced Metal-Free Catalytic Degradation of Organic Pollutants over Carbon-Dot-Based Carbocatalysts Synthesized from Biomass.

    PubMed

    Wang, Hui; Zhuang, Jianqin; Velado, David; Wei, Zengyan; Matsui, Hiroshi; Zhou, Shuiqin

    2015-12-23

    Cost-efficient nanoparticle carbocatalysts composed of fluorescent carbon dots (CDs) embedded in carbon matrix were synthesized via one-step acid-assisted hydrothermal treatment (200 °C) of glucose. These as-synthesized CD-based carbocatalysts have excellent photoluminescence (PL) properties over a broad range of wavelengths and the external visible or NIR irradiation on the carbocatalysts could produce electrons to form electron-hole (e(-)-h(+)) pairs on the surface of carbocatalysts. These restant electron-hole pairs will react with the adsorbed oxidants/reducers on the surface of the CD-based carbocatalysts to produce active radicals for reduction of 4-nitrophenol and degradation of dye molecules. Moreover, the local temperature increase over CD-based carbocatalyst under NIR irradiation can enhance the electron transfer rate between the organic molecules and CD-based carbocatalysts, thus obviously increase the catalytic activity of the CD-based carbocatalyst for the reduction of 4-nitrophenol and the degradation of dye molecules. Such a type of CD-based carbocatalysts with excellent properties and highly efficient metal-free photocatalytic activities is an ideal candidate as photocatalysts for the reduction of organic pollutants under visible light and NIR radiation.

  3. Heavy metals in Antarctic organisms

    SciTech Connect

    Moreno, J.E.A. de; Moreno, V.J.; Gerpe, M.S.; Vodopivez, C.

    1997-02-01

    To evaluate levels of essential (zinc and copper) and non-essential (mercury and cadmium) heavy metals, 34 species of organisms from different areas close to the Antarctic Peninsula were analysed. These included algae, filter-feeders, omnivorous invertebrates and vertebrates. Mercury was not detected, while cadmium was found in the majority of organisms analysed (detection limit was 0.05 ppm for both metals). The highest cadmium concentration was observed in the starfish Odontaster validus. Anthozoans, sipunculids and nudibranchs showed maximum levels of zinc, while the highest copper level was found in the gastropod Trophon brevispira. Mercury and cadmium levels in fishes were below the detection limit. Concentrations of essential and non-essential metals in birds were highest in liver followed by muscle and eggs. Cadmium and mercury levels in muscle of southern elephant seals were above the detection limit, whereas in Antarctic fur seals they were below it. The objective of the study was to gather baseline information for metals in Antarctic Ocean biota that may be needed to detect, measure and monitor future environmental changes. 46 refs., 7 figs., 8 tabs.

  4. Ultra-sensitive near-infrared fiber-optic gas sensors enhanced by metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Chong, Xinyuan; Kim, Ki-Joong; Li, Erwen; Zhang, Yujing; Ohodnicki, Paul R.; Chang, Chih-Hung; Wang, Alan X.

    2016-03-01

    We demonstrate ultra-sensitive near-infrared (NIR) fiber-optic gas sensors enhanced by metalorganic framework (MOF) Cu-BTC (BTC=benzene-1,3,5- tricarboxylate), which is coated on a single-mode optical fiber. For the first time, we obtained high-resolution NIR spectroscopy of CO2 adsorbed in MOF without seeing any rotational side band. Real-time measurement showed different response time depending on the concentration of CO2, which is attributed to the complex adsorption and desorption mechanism of CO2 in Cu-BTC. The lowest detection limit of CO2 we achieved is 20 ppm with only 5-cm long Cu-BTC film.

  5. M2(m-dobdc) (M = Mg, Mn, Fe, Co, Ni) metal-organic frameworks exhibiting increased charge density and enhanced H2 binding at the open metal sites.

    PubMed

    Kapelewski, Matthew T; Geier, Stephen J; Hudson, Matthew R; Stück, David; Mason, Jarad A; Nelson, Jocienne N; Xiao, Dianne J; Hulvey, Zeric; Gilmour, Elizabeth; FitzGerald, Stephen A; Head-Gordon, Martin; Brown, Craig M; Long, Jeffrey R

    2014-08-27

    The well-known frameworks of the type M2(dobdc) (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) have numerous potential applications in gas storage and separations, owing to their exceptionally high concentration of coordinatively unsaturated metal surface sites, which can interact strongly with small gas molecules such as H2. Employing a related meta-functionalized linker that is readily obtained from resorcinol, we now report a family of structural isomers of this framework, M2(m-dobdc) (M = Mg, Mn, Fe, Co, Ni; m-dobdc(4-) = 4,6-dioxido-1,3-benzenedicarboxylate), featuring exposed M(2+) cation sites with a higher apparent charge density. The regioisomeric linker alters the symmetry of the ligand field at the metal sites, leading to increases of 0.4-1.5 kJ/mol in the H2 binding enthalpies relative to M2(dobdc). A variety of techniques, including powder X-ray and neutron diffraction, inelastic neutron scattering, infrared spectroscopy, and first-principles electronic structure calculations, are applied in elucidating how these subtle structural and electronic differences give rise to such increases. Importantly, similar enhancements can be anticipated for the gas storage and separation properties of this new family of robust and potentially inexpensive metal-organic frameworks.

  6. One-pot synthesis of binary metal organic frameworks (HKUST-1 and UiO-66) for enhanced adsorptive removal of water contaminants.

    PubMed

    Azhar, Muhammad Rizwan; Abid, Hussein Rasool; Sun, Hongqi; Periasamy, Vijay; Tadé, Moses O; Wang, Shaobin

    2017-03-15

    In this study, binary metal organic frameworks (MOFs) with HKUST-1 and UiO-66 have been synthesized in a one-pot process. The synthesized MOFs were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption, and thermogravimetric analysis (TGA). The meso-porosity and thermal stability of the binary MOFs were higher than those of single HKUST-1 or UiO-66. The synthesized MOF hybrids were then tested for adsorptive removal of methylene blue (MB) from wastewater in terms of kinetic and isothermal adsorption as compared to a commercially available activated carbon (AC). All the synthesized MOFs showed significant removal of MB under a wide range of pH. The adsorption capacities of HKUST-1 are higher than UiO-66 and commercial AC while the binary MOFs presented an even higher adsorption capacity than single MOFs. This is the first time that binary HKUST-1 and UiO-66 MOFs have been successfully synthesized and demonstrated enhanced adsorptive removal of contaminants. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Demonstration of InAlN/AlGaN high electron mobility transistors with an enhanced breakdown voltage by pulsed metal organic chemical vapor deposition

    SciTech Connect

    Xue, JunShuai Zhang, JinCheng; Hao, Yue

    2016-01-04

    In this work, InAlN/AlGaN heterostructures employing wider bandgap AlGaN instead of conventional GaN channel were grown on sapphire substrate by pulsed metal organic chemical vapor deposition, where the nominal Al composition in InAlN barrier and AlGaN channel were chosen to be 83% and 5%, respectively, to achieve close lattice-matched condition. An electron mobility of 511 cm{sup 2}/V s along with a sheet carrier density of 1.88 × 10{sup 13 }cm{sup −2} were revealed in the prepared heterostructures, both of which were lower compared with lattice-matched InAlN/GaN due to increased intrinsic alloy disorder scattering resulting from AlGaN channel and compressively piezoelectric polarization in barrier, respectively. While the high electron mobility transistor (HEMT) processed on these structures not only exhibited a sufficiently high drain output current density of 854 mA/mm but also demonstrated a significantly enhanced breakdown voltage of 87 V, which is twice higher than that of reported InAlN/GaN HEMT with the same device dimension, potential characteristics for high-voltage operation of GaN-based electronic devices.

  8. Ruthenium(II) Complex Incorporated UiO-67 Metal-Organic Framework Nanoparticles for Enhanced Two-Photon Fluorescence Imaging and Photodynamic Cancer Therapy.

    PubMed

    Chen, Rui; Zhang, Jinfeng; Chelora, Jipsa; Xiong, Yuan; Kershaw, Stephen V; Li, King Fai; Lo, Pik-Kwan; Cheah, Kok Wai; Rogach, Andrey L; Zapien, Juan Antonio; Lee, Chun-Sing

    2017-02-22

    Ruthenium(II) tris(bipyridyl) cationic complex (Ru(bpy)3(2+)) incorporated UiO-67 (Universitetet i Oslo) nanoscale metal-organic frameworks (NMOFs) with an average diameter of ∼92 nm were developed as theranostic nanoplatform for in vitro two-photon fluorescence imaging and photodynamic therapy. After incorporation into porous UiO-67 nanoparticles, the quantum yield, luminescence lifetime, and two-photon fluorescence intensity of Ru(bpy)3(2+) guest molecules were much improved owing to the steric confinement effect of MOF pores. Benefiting from these merits, the as-synthesized nanoparticles managed to be internalized by A549 cells while providing excellent red fluorescence in cytoplasm upon excitation with 880 nm irradiation. Photodynamic therapeutic application of the Ru(bpy)3(2+)-incorporated UiO-67 NMOFs was investigated in vitro. The Ru(bpy)3(2+)-incorporated UiO-67 NMOFs exhibited good biocompatibility without irradiation while having good cell-killing rates upon irradiation. In view of these facts, the developed Ru(bpy)3(2+)-incorporated NMOFs give a new potential pathway to achieve enhanced two-photon fluorescence imaging and photodynamic therapy.

  9. Method of stripping metals from organic solvents

    DOEpatents

    Todd, Terry A.; Law, Jack D.; Herbst, R. Scott; Romanovskiy, Valeriy N.; Smirnov, Igor V.; Babain, Vasily A.; Esimantovski, Vyatcheslav M.

    2009-02-24

    A new method to strip metals from organic solvents in a manner that allows for the recycle of the stripping agent. The method utilizes carbonate solutions of organic amines with complexants, in low concentrations, to strip metals from organic solvents. The method allows for the distillation and reuse of organic amines. The concentrated metal/complexant fraction from distillation is more amenable to immobilization than solutions resulting from current practice.

  10. Gas adsorption on metal-organic frameworks

    DOEpatents

    Willis, Richard R [Cary, IL; Low, John J. , Faheem, Syed A.; Benin, Annabelle I [Oak Forest, IL; Snurr, Randall Q [Evanston, IL; Yazaydin, Ahmet Ozgur [Evanston, IL

    2012-07-24

    The present invention involves the use of certain metal organic frameworks that have been treated with water or another metal titrant in the storage of carbon dioxide. The capacity of these frameworks is significantly increased through this treatment.

  11. Attention enhances apparent perceptual organization.

    PubMed

    Barbot, Antoine; Liu, Sirui; Kimchi, Ruth; Carrasco, Marisa

    2017-08-28

    Perceptual organization and selective attention are two crucial processes that influence how we perceive visual information. The former structures complex visual inputs into coherent units, whereas the later selects relevant information. Attention and perceptual organization can modulate each other, affecting visual processing and performance in various tasks and conditions. Here, we tested whether attention can alter the way multiple elements appear to be perceptually organized. We manipulated covert spatial attention using a rapid serial visual presentation task, and measured perceptual organization of two multielements arrays organized by luminance similarity as rows or columns, at both the attended and unattended locations. We found that the apparent perceptual organization of the multielement arrays is intensified when attended and attenuated when unattended. We ruled out response bias as an alternative explanation. These findings reveal that attention enhances the appearance of perceptual organization, a midlevel vision process, altering the way we perceive our visual environment.

  12. Investigation of metal hydride nanoparticles templated in metal organic frameworks.

    SciTech Connect

    Jacobs, Benjamin W.; Herberg, Julie L.; Highley, Aaron M.; Grossman, Jeffrey; Wagner, Lucas; Bhakta, Raghu; Peaslee, D.; Allendorf, Mark D.; Liu, X.; Behrens, Richard, Jr.; Majzoub, Eric H.

    2010-11-01

    Hydrogen is proposed as an ideal carrier for storage, transport, and conversion of energy. However, its storage is a key problem in the development of hydrogen economy. Metal hydrides hold promise in effectively storing hydrogen. For this reason, metal hydrides have been the focus of intensive research. The chemical bonds in light metal hydrides are predominantly covalent, polar covalent or ionic. These bonds are often strong, resulting in high thermodynamic stability and low equilibrium hydrogen pressures. In addition, the directionality of the covalent/ionic bonds in these systems leads to large activation barriers for atomic motion, resulting in slow hydrogen sorption kinetics and limited reversibility. One method for enhancing reaction kinetics is to reduce the size of the metal hydrides to nano scale. This method exploits the short diffusion distances and constrained environment that exist in nanoscale hydride materials. In order to reduce the particle size of metal hydrides, mechanical ball milling is widely used. However, microscopic mechanisms responsible for the changes in kinetics resulting from ball milling are still being investigated. The objective of this work is to use metal organic frameworks (MOFs) as templates for the synthesis of nano-scale NaAlH4 particles, to measure the H2 desorption kinetics and thermodynamics, and to determine quantitative differences from corresponding bulk properties. Metal-organic frameworks (MOFs) offer an attractive alternative to traditional scaffolds because their ordered crystalline lattice provides a highly controlled and understandable environment. The present work demonstrates that MOFs are stable hosts for metal hydrides and their reactive precursors and that they can be used as templates to form metal hydride nanoclusters on the scale of their pores (1-2 nm). We find that using the MOF HKUST-1 as template, NaAlH4 nanoclusters as small as 8 formula units can be synthesized inside the pores. A detailed picture of

  13. Microporous Metal Organic Materials for Hydrogen Storage

    SciTech Connect

    S. G. Sankar; Jing Li; Karl Johnson

    2008-11-30

    We have examined a number of Metal Organic Framework Materials for their potential in hydrogen storage applications. Results obtained in this study may, in general, be summarized as follows: (1) We have identified a new family of porous metal organic framework materials with the compositions M (bdc) (ted){sub 0.5}, {l_brace}M = Zn or Co, bdc = biphenyl dicarboxylate and ted = triethylene diamine{r_brace} that adsorb large quantities of hydrogen ({approx}4.6 wt%) at 77 K and a hydrogen pressure of 50 atm. The modeling performed on these materials agree reasonably well with the experimental results. (2) In some instances, such as in Y{sub 2}(sdba){sub 3}, even though the modeling predicted the possibility of hydrogen adsorption (although only small quantities, {approx}1.2 wt%, 77 K, 50 atm. hydrogen), our experiments indicate that the sample does not adsorb any hydrogen. This may be related to the fact that the pores are extremely small or may be attributed to the lack of proper activation process. (3) Some samples such as Zn (tbip) (tbip = 5-tert butyl isophthalate) exhibit hysteresis characteristics in hydrogen sorption between adsorption and desorption runs. Modeling studies on this sample show good agreement with the desorption behavior. It is necessary to conduct additional studies to fully understand this behavior. (4) Molecular simulations have demonstrated the need to enhance the solid-fluid potential of interaction in order to achieve much higher adsorption amounts at room temperature. We speculate that this may be accomplished through incorporation of light transition metals, such as titanium and scandium, into the metal organic framework materials.

  14. Identification of a mechanism by which the methylmercury antidotes N-acetylcysteine and dimercaptopropanesulfonate enhance urinary metal excretion: transport by the renal organic anion transporter-1.

    PubMed

    Koh, Albert S; Simmons-Willis, Tracey A; Pritchard, John B; Grassl, Steven M; Ballatori, Nazzareno

    2002-10-01

    N-Acetylcysteine (NAC) and dimercaptopropanesulfonate (DMPS) are sulfhydryl-containing compounds that produce a dramatic acceleration of urinary methylmercury (MeHg) excretion in poisoned animals, but the molecular mechanism for this effect is unknown. NAC and DMPS are themselves excreted in urine in high concentrations. The present study tested the hypothesis that the complexes formed between MeHg and these anionic chelating agents are transported from blood into proximal tubule cells by the basolateral membrane organic anion transporters (Oat) 1 and Oat3. Xenopus laevis oocytes expressing rat Oat1 showed increased uptake of [(14)C]MeHg when complexed with either NAC or DMPS but not when complexed with L-cysteine, glutathione, dimercaptosuccinate, penicillamine, or gamma-glutamylcysteine. In contrast, none of these MeHg complexes were transported by Oat3-expressing oocytes. The apparent K(m) values for Oat1-mediated transport were 31 +/- 2 microM for MeHg-NAC and 9 +/- 2 microM for MeHg-DMPS, indicating that these are relatively high-affinity substrates. Oat1-mediated uptake of [(14)C]MeHg-NAC and [(14)C]MeHg-DMPS was inhibited by prototypical substrates for Oat1, including p-aminohippurate (PAH), and was trans-stimulated when oocytes were preloaded with 2 mM glutarate but not glutamate. Conversely, efflux of [(3)H]PAH from Oat1-expressing oocytes was trans-stimulated by glutarate, PAH, NAC, DMPS, MeHg-NAC, MeHg-DMPS, and a mercapturic acid, indicating that these are transported solutes. [(3)H]PAH uptake was competitively inhibited by NAC (K(i) of 2.0 +/- 0.3 mM) and DMPS (K(i) of 0.10 +/- 0.02 mM), providing further evidence that these chelating agents are substrates for Oat1. These results indicate that the MeHg antidotes NAC and DMPS and their mercaptide complexes are transported by Oat1 but are comparatively poor substrates for Oat3. This is the first molecular identification of a transport mechanism by which these antidotes may enhance urinary excretion of

  15. Thiol-functionalization of metal-organic framework by a facile coordination-based postsynthetic strategy and enhanced removal of Hg2+ from water.

    PubMed

    Ke, Fei; Qiu, Ling-Guang; Yuan, Yu-Peng; Peng, Fu-Min; Jiang, Xia; Xie, An-Jian; Shen, Yu-Hua; Zhu, Jun-Fa

    2011-11-30

    The presence of coordinatively unsaturated metal centers in metal-organic frameworks (MOFs) provides an accessible way to selectively functionalize MOFs through coordination bonds. In this work, we describe thiol-functionalization of MOFs by choosing a well known three-dimensional (3D) Cu-based MOF, i.e. [Cu(3)(BTC)(2)(H(2)O)(3)](n) (HKUST-1, BTC=benzene-1,3,5-tricarboxylate), by a facile coordination-based postsynthetic strategy, and demonstrate their application for removal of heavy metal ion from water. A series of [Cu(3)(BTC)(2)](n) samples stoichiometrically decorated with thiol groups has been prepared through coordination bonding of coordinatively unsaturated metal centers in HKUST-1 with -SH group in dithioglycol. The obtained thiol-functionalized samples were characterized by powder X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy, infrared spectroscopy, and N(2) sorption-desorption isothermal. Significantly, the thiol-functionalized [Cu(3)(BTC)(2)](n) exhibited remarkably high adsorption affinity (K(d)=4.73 × 10(5)mL g(-1)) and high adsorption capacity (714.29 mg g(-1)) for Hg(2+) adsorption from water, while the unfunctionalized HKUST-1 showed no adsorption of Hg(2+) under the same condition. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Metal-enhanced fluorescence of carbon nanotubes.

    PubMed

    Hong, Guosong; Tabakman, Scott M; Welsher, Kevin; Wang, Hailiang; Wang, Xinran; Dai, Hongjie

    2010-11-17

    The photoluminescence (PL) quantum yield of single-walled carbon nanotubes (SWNTs) is relatively low, with various quenching effects by metallic species reported in the literature. Here, we report the first case of metal enhanced fluorescence (MEF) of surfactant-coated carbon nanotubes on nanostructured gold substrates. The photoluminescence quantum yield of SWNTs is observed to be enhanced more than 10-fold. The dependence of fluorescence enhancement on metal-nanotube distance and on the surface plasmon resonance (SPR) of the gold substrate for various SWNT chiralities is measured to reveal the mechanism of enhancement. Surfactant-coated SWNTs in direct contact with metal exhibit strong MEF without quenching, suggesting a small quenching distance for SWNTs on the order of the van der Waals distance, beyond which the intrinsically fast nonradiative decay rate in nanotubes is little enhanced by metal. The metal enhanced fluorescence of SWNTs is attributed to radiative lifetime shortening through resonance coupling of SWNT emission to the reradiating dipolar plasmonic modes in the metal.

  17. Multiaxis sensing using metal organic frameworks

    DOEpatents

    Talin, Albert Alec; Allendorf, Mark D.; Leonard, Francois; Stavila, Vitalie

    2017-01-17

    A sensor device including a sensor substrate; and a thin film comprising a porous metal organic framework (MOF) on the substrate that presents more than one transduction mechanism when exposed to an analyte. A method including exposing a porous metal organic framework (MOF) on a substrate to an analyte; and identifying more than one transduction mechanism in response to the exposure to the analyte.

  18. Microcavity-Free Broadband Light Outcoupling Enhancement in Flexible Organic Light-Emitting Diodes with Nanostructured Transparent Metal-Dielectric Composite Electrodes.

    PubMed

    Xu, Lu-Hai; Ou, Qing-Dong; Li, Yan-Qing; Zhang, Yi-Bo; Zhao, Xin-Dong; Xiang, Heng-Yang; Chen, Jing-De; Zhou, Lei; Lee, Shuit-Tong; Tang, Jian-Xin

    2016-01-26

    Flexible organic light-emitting diodes (OLEDs) hold great promise for future bendable display and curved lighting applications. One key challenge of high-performance flexible OLEDs is to develop new flexible transparent conductive electrodes with superior mechanical, electrical, and optical properties. Herein, an effective nanostructured metal/dielectric composite electrode on a plastic substrate is reported by combining a quasi-random outcoupling structure for broadband and angle-independent light outcoupling of white emission with an ultrathin metal alloy film for optimum optical transparency, electrical conduction, and mechanical flexibility. The microcavity effect and surface plasmonic loss can be remarkably reduced in white flexible OLEDs, resulting in a substantial increase in the external quantum efficiency and power efficiency to 47.2% and 112.4 lm W(-1).

  19. Minerals with metal-organic framework structures.

    PubMed

    Huskić, Igor; Pekov, Igor V; Krivovichev, Sergey V; Friščić, Tomislav

    2016-08-01

    Metal-organic frameworks (MOFs) are an increasingly important family of advanced materials based on open, nanometer-scale metal-organic architectures, whose design and synthesis are based on the directed assembly of carefully designed subunits. We now demonstrate an unexpected link between mineralogy and MOF chemistry by discovering that the rare organic minerals stepanovite and zhemchuzhnikovite exhibit structures found in well-established magnetic and proton-conducting metal oxalate MOFs. Structures of stepanovite and zhemchuzhnikovite, exhibiting almost nanometer-wide and guest-filled apertures and channels, respectively, change the perspective of MOFs as exclusively artificial materials and represent, so far, unique examples of open framework architectures in organic minerals.

  20. Synthesis of a metal-organic framework confined in periodic mesoporous silica with enhanced hydrostability as a novel fiber coating for solid-phase microextraction.

    PubMed

    Abolghasemi, Mir Mahdi; Yousefi, Vahid; Piryaei, Marzieh

    2015-04-01

    A metal-organic framework/periodic mesoporous silica (MOF-5@SBA-15) hybrid material has been prepared by using SBA-15 as a matrix. The prepared MOF-5@SBA-15 hybrid material was then deposited on a stainless-steel wire to obtain the fiber for the solid-phase microextraction of phenolic compounds. Modifications in the metal-organic framework structure have proven to improve the extraction performance of MOF/SBA-15 hybrid materials, compared to pure MOF-5 and SBA-15. Optimum conditions include an extraction temperature of 75°C, a desorption temperature of 260°C, and a salt concentration of 20% w/v. The dynamic linear range and limit of detection range from 0.1-500 and from 0.01-3.12 ng/mL, respectively. The repeatability for one fiber (n = 3), expressed as relative standard deviation, is between 4.3 and 9.6%. The method offers the advantage of being simple to use, rapid, and low cost, the thermal stability of the fiber, and high relative recovery (compared to conventional methods) represent additional attractive features.

  1. Enhanced phytoremediation of mixed heavy metal (mercury)-organic pollutants (trichloroethylene) with transgenic alfalfa co-expressing glutathione S-transferase and human P450 2E1.

    PubMed

    Zhang, Yuanyuan; Liu, Junhong; Zhou, Yuanming; Gong, Tingyun; Wang, Jing; Ge, Yinlin

    2013-09-15

    Soil contamination is a global environmental problem and many efforts have been made to find efficient remediation methods over the last decade. Moreover, remediation of mixed contaminated soils are more difficult. In the present study, transgenic alfalfa plants pKHCG co-expressing glutathione S-transferase (GST) and human P450 2E1 (CYP2E1) genes were used for phytoremediation of mixed mercury (Hg)-trichloroethylene (TCE) contaminants. Simultaneous expression of GST and CYP2E1 may produce a significant synergistic effect, and leads to improved resistance and accumulation to heavy metal-organic complex contaminants. Based on the tolerance and accumulation assays, pKHCG transgenic plants were more resistant to Hg/TCE complex pollutants and many folds higher in Hg/TCE-accumulation than the non-transgenic control plants in mixed contaminated soil. It is confirmed that GST and CYP2E1 co-expression may be a useful strategy to help achieve mixed heavy metal-organic pollutants phytoremediation.

  2. Metal-loaded organic scintillators for neutrino physics

    SciTech Connect

    Buck, Christian; Yeh, Minfang

    2016-08-03

    Organic liquid scintillators are used in many neutrino physics experiments of the past and present. In particular for low energy neutrinos when realtime and energy information are required, liquid scintillators have several advantages compared to other technologies. In many cases the organic liquid needs to be loaded with metal to enhance the neutrino signal over background events. Several metal loaded scintillators of the past suffered from chemical and optical instabilities, limiting the performance of these neutrino detectors. Different ways of metal loading are described in the article with a focus on recent techniques providing metal loaded scintillators that can be used under stable conditions for many years even in ton scale experiments. Lastly, we review applications of metal loaded scintillators in neutrino experiments and compare the performance as well as the prospects of different scintillator types.

  3. Metal-loaded organic scintillators for neutrino physics

    DOE PAGES

    Buck, Christian; Yeh, Minfang

    2016-08-03

    Organic liquid scintillators are used in many neutrino physics experiments of the past and present. In particular for low energy neutrinos when realtime and energy information are required, liquid scintillators have several advantages compared to other technologies. In many cases the organic liquid needs to be loaded with metal to enhance the neutrino signal over background events. Several metal loaded scintillators of the past suffered from chemical and optical instabilities, limiting the performance of these neutrino detectors. Different ways of metal loading are described in the article with a focus on recent techniques providing metal loaded scintillators that can bemore » used under stable conditions for many years even in ton scale experiments. Lastly, we review applications of metal loaded scintillators in neutrino experiments and compare the performance as well as the prospects of different scintillator types.« less

  4. Metal-loaded organic scintillators for neutrino physics

    SciTech Connect

    Buck, Christian; Yeh, Minfang

    2016-08-03

    Organic liquid scintillators are used in many neutrino physics experiments of the past and present. In particular for low energy neutrinos when realtime and energy information are required, liquid scintillators have several advantages compared to other technologies. In many cases the organic liquid needs to be loaded with metal to enhance the neutrino signal over background events. Several metal loaded scintillators of the past suffered from chemical and optical instabilities, limiting the performance of these neutrino detectors. Different ways of metal loading are described in the article with a focus on recent techniques providing metal loaded scintillators that can be used under stable conditions for many years even in ton scale experiments. Lastly, we review applications of metal loaded scintillators in neutrino experiments and compare the performance as well as the prospects of different scintillator types.

  5. Metal-loaded organic scintillators for neutrino physics

    NASA Astrophysics Data System (ADS)

    Buck, Christian; Yeh, Minfang

    2016-09-01

    Organic liquid scintillators are used in many neutrino physics experiments of the past and present. In particular for low energy neutrinos when realtime and energy information are required, liquid scintillators have several advantages compared to other technologies. In many cases the organic liquid needs to be loaded with metal to enhance the neutrino signal over background events. Several metal loaded scintillators of the past suffered from chemical and optical instabilities, limiting the performance of these neutrino detectors. Different ways of metal loading are described in the article with a focus on recent techniques providing metal loaded scintillators that can be used under stable conditions for many years even in ton scale experiments. Applications of metal loaded scintillators in neutrino experiments are reviewed and the performance as well as the prospects of different scintillator types are compared.

  6. Direct photocatalysis of supported metal nanostructures for organic synthesis

    NASA Astrophysics Data System (ADS)

    Wu, Xiayan; Jaatinen, Esa; Sarina, Sarina; Zhu, Huai Yong

    2017-07-01

    Many organic synthesis systems use thermal catalysis to achieve higher product efficiency, and it is of interest to drive reactions by light irradiation at moderate reaction conditions. Other than semiconductors, recent reports have shown that metal nanostructures can be used as direct photocatalysts to drive chemical reactions. In this review, we summarize recent progress in direct photocatalysis in organic synthesis using plasmonic and non-plasmonic metal nanostructures. It starts with a comprehensive introduction to surface plasmons and the role of interband transitions in non-plasmonic metal nanostructures. The application of metal nanostructures in organic synthesis is systematically reviewed, followed by the reaction mechanisms; the role of light-excited energetic electrons, enhanced electromagnetic fields and the photothermal effect are detailed. The influence of light intensity and wavelength is discussed, as well as the critical parameters of photocatalyst design. Finally, the outlook and future opportunities of this new exciting field will be discussed.

  7. Magnetism in metal-organic capsules

    SciTech Connect

    Atwood, Jerry L.; Brechin, Euan K; Dalgarno, Scott J.; Inglis, Ross; Jones, Leigh F.; Mossine, Andrew; Paterson, Martin J.; Power, Nicholas P.; Teat, Simon J.

    2010-01-07

    Nickel and cobalt seamed metal-organic capsules have been isolated and studied using structural, magnetic and computational approaches. Antiferromagnetic exchange in the Ni capsule results from coordination environments enforced by the capsule framework.

  8. Metal-organic framework nanofibers via electrospinning.

    PubMed

    Ostermann, Rainer; Cravillon, Janosch; Weidmann, Christoph; Wiebcke, Michael; Smarsly, Bernd M

    2011-01-07

    A hierarchical system of highly porous nanofibers has been prepared by electrospinning MOF (metal-organic framework) nanoparticles with suitable carrier polymers. Nitrogen adsorption proved the MOF nanoparticles to be fully accessible inside the polymeric fibers.

  9. Metal-Organic Framework Templated Synthesis of Ultrasmall Catalyst Loaded ZnO/ZnCo2O4 Hollow Spheres for Enhanced Gas Sensing Properties

    PubMed Central

    Koo, Won-Tae; Choi, Seon-Jin; Jang, Ji-Soo; Kim, Il-Doo

    2017-01-01

    To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2–3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2O4 HSs. In addition, the heterojunctions of Pd-ZnO, Pd-ZnCo2O4, and ZnO-ZnCo2O4 were formed on each phase. The synthesized Pd-ZnO/ZnCo2O4 HSs exhibited extremely high selectivity toward acetone gas with notable sensitivity (S = 69% to 5 ppm at 250 °C). The results demonstrate that MOF driven ultrasmall catalyst loaded TMO HSs were highly effective platform for high performance chemical gas sensors. PMID:28327599

  10. Metal-Organic Framework Templated Synthesis of Ultrasmall Catalyst Loaded ZnO/ZnCo2O4 Hollow Spheres for Enhanced Gas Sensing Properties

    NASA Astrophysics Data System (ADS)

    Koo, Won-Tae; Choi, Seon-Jin; Jang, Ji-Soo; Kim, Il-Doo

    2017-03-01

    To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2–3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2O4 HSs. In addition, the heterojunctions of Pd-ZnO, Pd-ZnCo2O4, and ZnO-ZnCo2O4 were formed on each phase. The synthesized Pd-ZnO/ZnCo2O4 HSs exhibited extremely high selectivity toward acetone gas with notable sensitivity (S = 69% to 5 ppm at 250 °C). The results demonstrate that MOF driven ultrasmall catalyst loaded TMO HSs were highly effective platform for high performance chemical gas sensors.

  11. An amide-containing metal-organic tetrahedron responding to a spin-trapping reaction in a fluorescent enhancement manner for biological imaging of NO in living cells.

    PubMed

    Wang, Jian; He, Cheng; Wu, Pengyan; Wang, Jing; Duan, Chunying

    2011-08-17

    Metal-organic polyhedra represent a unique class of functional molecular containers that display interesting molecular recognition properties and fascinating reactivity reminiscent of the natural enzymes. By incorporating a triphenylamine moiety as a bright blue emitter, a robust cerium-based tetrahedron was developed as a luminescent detector of nitronyl nitroxide (PTIO), a specific spin-labeling nitric oxide (NO) trapper. The tetrahedron encapsulates molecules of NO and PTIO within the cavity to prompt the spin-trapping reaction and transforms the normal EPR responses into a more sensitively luminescent signaling system with the limit of detection improved to 5 nM. Twelve-fold amide groups are also functionalized within the tetrahedron to modify the hydrophilic/lipophilic environment, ensuring the successful application of biological imaging in living cells.

  12. Polarization-diverse light absorption enhancement in organic photovoltaic structures with one-dimensional, long-pitch metallic gratings: Design and experiment

    NASA Astrophysics Data System (ADS)

    Liu, Yifen; Dhakal, Rabin; Dalal, Vikram; Kim, Jaeyoun

    2012-12-01

    We report the design and experimental realization of an organic photovoltaic device structure that can trap incident light in all polarization states without relying on two-dimensional, short-pitch (<400 nm) gratings. Instead, we utilized easily patternable one-dimensional, long-pitch (>1000 nm) gratings and achieved the polarization diversity through balanced allocation of the plasmonic and guided mode-based light trapping routes to different polarization states. The experimental results showed strong enhancements in light absorption in all polarization states that would translate into a 15%-25% increase in the power conversion efficiency.

  13. Enhancement of hydrogen adsorption in metal-organic frameworks by the incorporation of the sulfonate group and Li cations. A multiscale computational study.

    PubMed

    Mavrandonakis, Andreas; Klontzas, Emmanouel; Tylianakis, Emmanuel; Froudakis, George E

    2009-09-23

    By means of ab initio methods, the effect on the H(2) storage ability of a newly proposed organic linker for IRMOF-14 has been studied. The linker comprises a negatively charged sulfonate (-SO(3)(-1)) group in combination with a Li cation. It is found that these two charged groups significantly increase the interaction energy between the hydrogen molecules and the new proposed organic linker of the MOF. The substituted group of the linker may host up to six hydrogen molecules with an average interaction energy of 1.5 kcal/mol per H(2) molecule. This value is three times larger than the binding energy over the bare linker that has been obtained from DFT calculations. GCMC atomistic simulations verified that the proposed material can be qualified among the highest adsorbing materials for volumetric capture of H(2), especially at ambient conditions. This functionalization strategy can be applied in many different MOF structures to enhance their storage abilities.

  14. Coating to enhance metal-polymer adhesion

    SciTech Connect

    Parthasarathi, A.; Mahulikar, D.

    1996-12-31

    An ultra-thin electroplated coating has been developed to enhance adhesion of metals to polymers. The coating was developed for microelectronic packaging applications where it greatly improves adhesion of metal leadframes to plastic molding compounds. Recent tests show that the coating enhances adhesion of different metals to other types of adhesives as well and may thus have wider applicability. Results of adhesion tests with this coating, as well as its other characteristics such as corrosion resistance, are discussed. The coating is a very thin transparent electroplated coating containing zinc and chromium. It has been found to be effective on a variety of metal surfaces including copper alloys, Fe-Ni alloys, Al alloys, stainless steel, silver, nickel, Pd/Ni and Ni-Sn. Contact resistance measurements show that the coating has little or no effect on electrical resistivity.

  15. Near-infrared emitting ytterbium metal-organic frameworks with tunable excitation properties.

    PubMed

    White, Kiley A; Chengelis, Demetra A; Zeller, Matthias; Geib, Steven J; Szakos, Jessica; Petoud, Stéphane; Rosi, Nathaniel L

    2009-08-14

    The design of metal-organic frameworks (MOFs) incorporating near-infrared emitting ytterbium cations and organic sensitizers allows for the preparation of new materials with tunable and enhanced photophysical properties.

  16. Minerals with metal-organic framework structures

    PubMed Central

    Huskić, Igor; Pekov, Igor V.; Krivovichev, Sergey V.; Friščić, Tomislav

    2016-01-01

    Metal-organic frameworks (MOFs) are an increasingly important family of advanced materials based on open, nanometer-scale metal-organic architectures, whose design and synthesis are based on the directed assembly of carefully designed subunits. We now demonstrate an unexpected link between mineralogy and MOF chemistry by discovering that the rare organic minerals stepanovite and zhemchuzhnikovite exhibit structures found in well-established magnetic and proton-conducting metal oxalate MOFs. Structures of stepanovite and zhemchuzhnikovite, exhibiting almost nanometer-wide and guest-filled apertures and channels, respectively, change the perspective of MOFs as exclusively artificial materials and represent, so far, unique examples of open framework architectures in organic minerals. PMID:27532051

  17. Thin-Film Nanocomposite (TFN) Membranes Incorporated with Super-Hydrophilic Metal-Organic Framework (MOF) UiO-66: Toward Enhancement of Water Flux and Salt Rejection.

    PubMed

    Ma, Dangchen; Peh, Shing Bo; Han, Gang; Chen, Shing Bor

    2017-03-01

    Zirconiumv (IV)-carboxylate metal-organic framework (MOF) UiO-66 nanoparticles were successfully synthesized and incorporated in the polyamide (PA) selective layer to fabricate novel thin-film nanocomposite (TFN) membranes. Compared to unmodified pure polyamide thin-film composite (TFC) membranes, the incorporation of UiO-66 nanoparticles significantly changes the membrane morphology and chemistry, leading to an improvement of intrinsic separation properties due to the molecular sieving and superhydrophilic nature of UiO-66 particles. The best performing TFN-U2 (0.1 wt % particle loading) membrane not only shows a 52% increase of water permeability but also maintains salt rejection levels (∼95%) similar to the benchmark. The effects of UiO-66 loading on the forward osmosis (FO) performance were also investigated. Incorporation of 0.1 wt % UiO-66 produced a maximum water flux increase of 40% and 25% over the TFC control under PRO and FO modes, when 1 M NaCl was used as the draw solution against deionized water feed. Meanwhile, solute reverse flux was maintained at a relatively low level. In addition, TFN-U2 membrane displayed a relatively linear increase in FO water flux with increasing NaCl concentration up to 2.0 M, suggesting a slightly reduced internal concentration polarization effect. To our best knowledge, the current study is the first to consider implementation of Zr-MOFs (UiO-66) onto TFN-FO membranes.

  18. Enhanced output power of near-ultraviolet LEDs with AlGaN/GaN distributed Bragg reflectors on 6H-SiC by metal-organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Tao, Pengcheng; Liang, Hongwei; Xia, Xiaochuan; Liu, Yang; Jiang, Jianhua; Huang, Huishi; Feng, Qiuju; Shen, Rensheng; Luo, Yingmin; Du, Guotong

    2015-09-01

    Near-ultraviolet (UV) InGaN/AlGaN multiple quantum well (MQW) LEDs with 30 pairs AlGaN/GaN distributed Bragg reflectors (DBRs) were grown on 6H-SiC substrate by metal-organic chemical vapor deposition. A thin SiNx interlayer was introduced between the DBRs and n-GaN layer of the LED to reduce the threading dislocation density and result in enhancement the internal quantum efficiency (ηint) of the InGaN/AlGaN LED. The result indicates that the light output power for the LED with DBRs and SiNx interlayer was approximately 56% higher (at 350 mA) than the LED without DBRs and SiNx interlayer on 6H-SiC substrate, and this significant improvement in performance is attributed not only to the light extraction enhancement via the DBRs but also due to improve epilayer crystalline quality.

  19. Enhanced selective hydrogen desorption from metals

    SciTech Connect

    Knize, R.J.; Cecchi, J.L.

    1982-12-01

    The thermal desorption of hydrogen isotopes from a metal is usually a second order process, the rate for which becomes asymptotically slow. We present a method for enhancing the desorption rate of one particular isotope by maintaining a constant pressure of another molecular species. This results in an effective first order desorption and concomitant exponential decay of the concentration of the selected isotope. Data are presented for the enhanced desorption of deuterium from a Zr-Al getter. The results agree well with a theoretical model, which is discussed. This enhanced desorption method should be particularly useful for tritium operation in the Tokamak Fusion Test Reactor.

  20. Enhanced selective hydrogen desorption from metals

    SciTech Connect

    Knize, R.J.; Cecchi, J.L.

    1983-04-01

    The thermal desorption of hydrogen isotopes from a metal is usually a second order process the rate for which becomes asymptotically slow. We present a method for enhancing the desorption rate of one particular isotope by maintaining a constant pressure of another molecular species. This results in an effective first order desorption and concommitant exponential decay of the concentration of the selected isotope. Data is presented for the enhanced desorption of deuterium from a Zr--Al getter. The results agree well with a theoretical model, which is discussed. This enhanced desorption method should be particularly useful for tritium operation in the tokamak fusion test reactor.

  1. Self-exfoliated metal organic nanosheets via hydrolytic unfolding of metal organic polyhedra.

    PubMed

    Banerjee, Rahul; Garai, Bikash; Mallick, Arjit; Das, Anuja; Mukherjee, Rabibrata

    2017-04-04

    Few layer thick metal-organic nanosheets have been synthesized using water-assisted solid state transformation through a combined top-down and bottom-up approach. The metal-organic polyhedra (MOPs) convert into metal-organic frameworks (MOFs) which subsequently self-exfoliate into few layered metal-organic nanosheets. These MOP crystals experience a hydrophobicity gradient with the inner surface during contact with water because of the existence of hydrophobic spikes on their outer surface. When the amount of water available for interaction is higher, the resultant layers are not stacked to form bulk materials; instead few layered nanosheets with high uniformity were obtained in high yield. The phenomenon has resulted high yield production of uniformly distributed layered metal-organic nanosheets from three different MOPs, showing its general adaptability.

  2. Emerging Multifunctional Metal-Organic Framework Materials.

    PubMed

    Li, Bin; Wen, Hui-Min; Cui, Yuanjing; Zhou, Wei; Qian, Guodong; Chen, Banglin

    2016-10-01

    Metal-organic frameworks (MOFs), also known as coordination polymers, represent an interesting type of solid crystalline materials that can be straightforwardly self-assembled through the coordination of metal ions/clusters with organic linkers. Owing to the modular nature and mild conditions of MOF synthesis, the porosities of MOF materials can be systematically tuned by judicious selection of molecular building blocks, and a variety of functional sites/groups can be introduced into metal ions/clusters, organic linkers, or pore spaces through pre-designing or post-synthetic approaches. These unique advantages enable MOFs to be used as a highly versatile and tunable platform for exploring multifunctional MOF materials. Here, the bright potential of MOF materials as emerging multifunctional materials is highlighted in some of the most important applications for gas storage and separation, optical, electric and magnetic materials, chemical sensing, catalysis, and biomedicine.

  3. Methane storage in metal-organic frameworks.

    PubMed

    He, Yabing; Zhou, Wei; Qian, Guodong; Chen, Banglin

    2014-08-21

    Natural gas (NG), whose main component is methane, is an attractive fuel for vehicular applications. Realization of safe, cheap and convenient means and materials for high-capacity methane storage can significantly facilitate the implementation of natural gas fuelled vehicles. The physisorption based process involving porous materials offers an efficient storage methodology and the emerging porous metal-organic frameworks have been explored as potential candidates because of their extraordinarily high porosities, tunable pore/cage sizes and easily immobilized functional sites. In this view, we provide an overview of the current status of metal-organic frameworks for methane storage.

  4. Field Enhancement using Noble Metal Structures

    NASA Astrophysics Data System (ADS)

    Liu, Benliang

    Resonance may be one of the most fundamental rules of nature. Electromagnetic resonance at nanometer scale could produce a giant field enhancement at optical frequency, providing a way to measure and control the process of atoms and molecules at single molecule scale. For example, the giant field enhancement would provide single molecule sensitivity for Raman scattering, which provides unique tools in measuring the quantity in extremely low concentration. In addition, light-emitting diodes could have high brightness but low input power that would be revolutionary in the optoelectronic industry. Although light enhancement is promising in several key technology areas, there are several challenges remain to be tackled. In particular, since the field enhancement is so strongly geometry dependent that slight modification of the geometry can lead to large variations in the outcome, a thorough understanding in how the geometry of the structure affects the field enhancement and creating proper methods to fabricate these structures reproducibly is of most importance. This thesis is devoted to design, fabrication and characterization of field enhancement generated on the surface of noble metals such as silver or gold with 1D structure. The s-polarized field enhancement arising from one-dimensional metal gratings is designed and optimized by using Rigorous Coupling Wave Analysis (RCWA). After optimization, the strongest enhancement factor is found to be 9.7 for 514nm wavelength light. The theoretical results arc confirmed by angle-dependent reflectivity measurements and the experimental results are found to support the theory. A novel single slit structure employing surface plasmon polaritons (SPPs) for enhancing the electric field is studied. SPPs are first generated on a 50 nm thick metal film using attenuated total reflection coupling, and they are subsequently coupled to the cavity mode induced by the single slit. As a result, the field enhancement is found at least 3

  5. Recent Developments of Metal and Metal Oxide Nanocatalysts in Organic Synthesis.

    PubMed

    Makawana, Jigar A; Sangani, Chetan B; Yao, Yong-Fang; Duan, Yong-Tao; Lv, Peng-Cheng; Zhu, Hai-Liang

    2016-01-01

    Recently, various nanomaterials have been used in many organic transformations as efficient catalysts. The development of new catalysts by nanoscale design has emerged as a fertile field for research and innovation. The ability of nanotechnology to enhance catalytic activity opens the potential to replace expensive catalysts with lower amounts of inexpensive nanocatalysts. Besides, development of efficient and environmentally friendly synthetic methodologies for the synthesis of compound libraries of medicinal scaffolds is an attractive area of research in both academic and pharmaceutical industry. According to above reports and needs, this review deals with applications of nanoparticles as catalysts in various organic syntheses. We detail the topic of organic transformations using nanoparticles: Metal Nanoparticles and Metal Oxide Nanoparticles. In the latter part, different Metal Oxide Nanoparticles, such as ZnO Nanoparticle, TiO2 Nanoparticle, and CuO Nanoparticle are discussed.

  6. Fluorescence enhancement of photoswitchable metal ion sensors

    NASA Astrophysics Data System (ADS)

    Sylvia, Georgina; Heng, Sabrina; Abell, Andrew D.

    2016-12-01

    Spiropyran-based fluorescence sensors are an ideal target for intracellular metal ion sensing, due to their biocompatibility, red emission frequency and photo-controlled reversible analyte binding for continuous signal monitoring. However, increasing the brightness of spiropyran-based sensors would extend their sensing capability for live-cell imaging. In this work we look to enhance the fluorescence of spiropyran-based sensors, by incorporating an additional fluorophore into the sensor design. We report a 5-membered monoazacrown bearing spiropyran with metal ion specificity, modified to incorporate the pyrene fluorophore. The effect of N-indole pyrene modification on the behavior of the spiropyran molecule is explored, with absorbance and fluorescence emission characterization. This first generation sensor provides an insight into fluorescence-enhancement of spiropyran molecules.

  7. Mechanism of metal cationization in organic SIMS

    NASA Astrophysics Data System (ADS)

    Wojciechowski, I.; Delcorte, A.; Gonze, X.; Bertrand, P.

    2001-09-01

    A mechanism for metal cationization of phenyl group containing hydrocarbons is discussed. Intact molecules and their fragments are emitted from a thin organic layer covering a metal surface bombarded by fast ions. It is shown that the process of associative ionization of a neutral hydrocarbon molecule and a neutral excited metal atom, occurring above the surface, may contribute to the yield of cationized molecules. To demonstrate this we have calculated the potential energy curves for the model system C 6H 6+Me (Me=Ag, Cu, Au) making use of the density functional theory. The initial states of the metal atoms approaching the benzene ring along the C 6 symmetry axis were set as the ground, ionic, and excited in ( n-1)d 9ns 2 electronic configuration.

  8. Optical absorption enhancement of hybrid-plasmonic-based metal-semiconductor-metal photodetector incorporating metal nanogratings and embedded metal nanoparticles.

    PubMed

    Tan, Chee Leong; Karar, Ayman; Alameh, Kamal; Lee, Yong Tak

    2013-01-28

    We propose and numerically demonstrate a high absorption hybrid-plasmonic-based metal semiconductor metal photodetector (MSM-PD) comprising metal nanogratings, a subwavelength slit and amorphous silicon or germanium embedded metal nanoparticles (NPs). Simulation results show that by optimizing the metal nanograting parameters, the subwavelength slit and the embedded metal NPs, a 1.3 order of magnitude increase in electric field is attained, leading to 28-fold absorption enhancement, in comparison with conventional MSM-PD structures. This is 3.5 times better than the absorption of surface plasmon polariton (SPP) based MSM-PD structures employing metal nanogratings and a subwavelength slit. This absorption enhancement is due to the ability of the embedded metal NPs to enhance their optical absorption and scattering properties through light-stimulated resonance aided by the conduction electrons of the NPs.

  9. Superhydrophobic perfluorinated metal-organic frameworks.

    PubMed

    Chen, Teng-Hao; Popov, Ilya; Zenasni, Oussama; Daugulis, Olafs; Miljanić, Ognjen Š

    2013-08-07

    Three perfluorinated Cu-based metal-organic frameworks (MOFs) were prepared starting from extensively fluorinated biphenyl-based ligands accessed via C-H functionalization. These new materials are highly hydrophobic: with water contact angles of up to 151 ± 1°, they are among the most water-repellent MOFs ever reported.

  10. Pore with gate: enhancement of the isosteric heat of adsorption of dihydrogen via postsynthetic cation exchange in metal-organic frameworks.

    PubMed

    Yang, Sihai; Martin, Gregory S B; Titman, Jeremy J; Blake, Alexander J; Allan, David R; Champness, Neil R; Schröder, Martin

    2011-10-03

    Three isostructural anionic frameworks {[(Hdma)(H(3)O)][In(2)(L(1))(2)]·4DMF·5H(2)O}(∞) (NOTT-206-solv), {[H(2)ppz][In(2)(L(2))(2)]·3.5DMF·5H(2)O}(∞) (NOTT-200-solv), and {[H(2)ppz][In(2)(L(3))(2)]·4DMF·5.5H(2)O}(∞) (NOTT-208-solv) (dma = dimethylamine; ppz = piperazine) each featuring organic countercations that selectively block the channels and act as pore gates have been prepared. The organic cations within the as-synthesized frameworks can be replaced by Li(+) ions to yield the corresponding Li(+)-containing frameworks {Li(1.2)(H(3)O)(0.8)[In(2)(L(1))(2)]·14H(2)O}(∞) (NOTT-207-solv), {Li(1.5)(H(3)O)(0.5)[In(2)(L(2))(2)]·11H(2)O}(∞) (NOTT-201-solv), and {Li(1.4)(H(3)O)(0.6)[In(2)(L(3))(2)]·4acetone·11H(2)O}(∞) (NOTT-209-solv) in which the pores are now unblocked. The desolvated framework materials NOTT-200a, NOTT-206a, and NOTT-208a display nonporous, hysteretic and reversible N(2) uptakes, respectively, while NOTT-206a and NOTT-200a provide a strong kinetic trap showing adsorption/desorption hysteresis with H(2). Single crystal X-ray analysis confirms that the Li(+) ions are either tetrahedrally (in NOTT-201-solv and NOTT-209-solv) or octahedrally (in NOTT-207-solv) coordinated by carboxylate oxygen atoms and/or water molecules. This is supported by (7)Li solid-state NMR spectroscopy. NOTT-209a, compared with NOTT-208a, shows a 31% enhancement in H(2) storage capacity coupled to a 38% increase in the isosteric heat of adsorption to 12 kJ/mol at zero coverage. Thus, by modulating the pore environment via postsynthetic cation exchange, the gas adsorption properties of the resultant MOF can be fine-tuned. This affords a methodology for the development of high capacity storage materials that may operate at more ambient temperatures.

  11. Metal and metal oxide nanoparticle synthesis from metal organic frameworks (MOFs): finding the border of metal and metal oxides

    NASA Astrophysics Data System (ADS)

    Das, Raja; Pachfule, Pradip; Banerjee, Rahul; Poddar, Pankaj

    2012-01-01

    Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co3O4, ZnO, Mn2O3, MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N2, whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N2. Another point of interest is the fact that we have found a unique relationship between the nanoparticle size and the distance between the secondary building units inside the MOF precursors. Interestingly, the crystallinity of the carbon matrix was also found to be greatly influenced by the environment (N2 and air) during thermolysis. Moreover, these nanoparticles dispersed in a carbon matrix showed promising H2 and CO2 adsorption properties depending on the environment used for the thermolysis of MOFs.Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co3O4, ZnO, Mn2O3, MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N2, whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N2. Another point of interest is the fact that we have

  12. Enhanced transmittance of metallic film with nanoaperture array

    NASA Astrophysics Data System (ADS)

    Xu, Ming; Ou, Xia-Li; Zhang, Xu-Lin; Liu, Yu-Shan; Gao, Qiang

    2016-09-01

    Metallic film as an indium tin oxide alternative, which shows excellent mechanical flexibility and high conductivity, has the ideal physical properties for flexible organic solar cells (OSCs). However, a bottleneck of metallic film was a lack of transmittance that limits the application in OSCs. We have demonstrated a nanoaperture metallic film fabricated by a template striping method, which can overcome the above-mentioned bottleneck. This metallic film has a random nanoaperture array. The size and shape of the nanoaperture were dependent on master templates. This metallic film with nanoaperture array is not only able to show high conductivity but also possesses tunable localized surface plasmon (LSP) resonance as well. The LSP could be coupled with dipole mode in nanostructure, which can account for the transmission enhancement and efficiently increase the light absorption of active layer in the OSCs. Moreover, this metallic film with nanoaperture array will exhibit particular advantage in flexible OSCs because the backing layer itself is a flexible substrate. The nanoaperture metallic film fabricated by this method as an electrode was a good choice for OSCs.

  13. Adsorption of volatile organic compounds in porous metal-organic frameworks functionalized by polyoxometalates

    NASA Astrophysics Data System (ADS)

    Ma, Feng-Ji; Liu, Shu-Xia; Liang, Da-Dong; Ren, Guo-Jian; Wei, Feng; Chen, Ya-Guang; Su, Zhong-Min

    2011-11-01

    The functionalization of porous metal-organic frameworks (Cu 3( BTC) 2) was achieved by incorporating Keggin-type polyoxometalates (POMs), and further optimized via alkali metal ion-exchange. In addition to thermal gravimetric analysis, IR, single-crystal X-ray diffraction, and powder X-ray diffraction, the adsorption properties were characterized by N 2 and volatile organic compounds (VOCs) adsorption measurements, including short-chain alcohols ( C<4), cyclohexane, benzene, and toluene. The adsorption enthalpies estimated by the modified Clausius-Clapeyron equation provided insight into the impact of POMs and alkali metal cations on the adsorption of VOCs. The introduction of POMs not only improved the stability, but also brought the increase of adsorption capacity by strengthening the interaction with gas molecules. Furthermore, the exchanged alkali metal cations acted as active sites to interact with adsorbates and enhanced the adsorption of VOCs.

  14. Spontaneous metal deposition from organic solutions for electronic materials applications

    NASA Astrophysics Data System (ADS)

    Fang, Rui

    Electrochemical deposition (ECD) has been used widely in the electronics industry. A novel "galvanic deposition" process was used for spontaneous and selective ECD of metal from organic solutions in contrast to the more conventional aqueous media. The more noble metal ions loaded in the organic solution are reduced and deposited onto the less noble metal substrate, which is simultaneously dissolved into the organic. Cu and Pd seed layers have been successfully deposited from organic solutions onto patterned and unpatterned pure aluminum and Al(0.5wt%Cu) thin films using this immersion displacement process. The Cu and Pd deposits were effectively used as catalytic sites for subsequent conventional electroless or electrolytic copper deposition. Further studies were performed to modify and optimize the organic deposition solution composition. These modified organic solutions could be used to deposit nearly continuous copper films on both unpatterned and patterned aluminum substrates. A patent disclosure on the modified organic deposition process was made to the University of Missouri and will be officially filed with the U.S. Patent Office. The EIS technique was one method used to characterize these high resistivity organic media. The organic solution resistivities were determined to be in the range of ˜108 O-cm but decreased to ˜10 6 O-cm with the addition of some modifying additives. Pd and Cu deposition have also been accomplished on various blanket and patterned Ti, TiN, Ta, and TaN barrier films. Some pre-treatment or in-situ etching in combination with ultrasonic or intensive mechanical agitation was necessary to activate the surface and enhance the metal deposition reaction. After seeding, continuous copper films were built up using a conventional electroless or electroplating process.

  15. Mechanical Alloying of Metal-Organic Frameworks.

    PubMed

    Panda, Tamas; Horike, Satoshi; Hagi, Keisuke; Ogiwara, Naoki; Kadota, Kentaro; Itakura, Tomoya; Tsujimoto, Masahiko; Kitagawa, Susumu

    2017-02-20

    The solvent-free mechanical milling process for two distinct metal-organic framework (MOF) crystals induced the formation of a solid solution, which is not feasible by conventional solution-based syntheses. X-ray and STEM-EDX studies revealed that performing mechanical milling under an Ar atmosphere promotes the high diffusivity of each metal ion in an amorphous solid matrix; the amorphous state turns into the porous crystalline structure by vapor exposure treatment to form a new phase of a MOF solid solution.

  16. Metal and metal oxide nanoparticle synthesis from metal organic frameworks (MOFs): finding the border of metal and metal oxides.

    PubMed

    Das, Raja; Pachfule, Pradip; Banerjee, Rahul; Poddar, Pankaj

    2012-01-21

    Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co(3)O(4), ZnO, Mn(2)O(3), MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N(2), whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N(2). Another point of interest is the fact that we have found a unique relationship between the nanoparticle size and the distance between the secondary building units inside the MOF precursors. Interestingly, the crystallinity of the carbon matrix was also found to be greatly influenced by the environment (N(2) and air) during thermolysis. Moreover, these nanoparticles dispersed in a carbon matrix showed promising H(2) and CO(2) adsorption properties depending on the environment used for the thermolysis of MOFs.

  17. Impacts of metal and metal oxide nanoparticles on marine organisms.

    PubMed

    Baker, Tony J; Tyler, Charles R; Galloway, Tamara S

    2014-03-01

    Increasing use of metal and metal oxide nanoparticles [Me(O)NPs] in products means many will inevitably find their way into marine systems. Their likely fate here is sedimentation following hetero-aggregation with natural organic matter and/or free anions, putting benthic, sediment-dwelling and filter feeding organisms most at risk. In marine systems, Me(O)NPs can absorb to micro-organisms with potential for trophic transfer following consumption. Filter feeders, especially bivalves, accumulate Me(O)NPs through trapping them in mucus prior to ingestion. Benthic in-fauna may directly ingest sedimented Me(O)NPs. In fish, uptake is principally via the gut following drinking, whilst Me(O)NPs caught in gill mucus may affect respiratory processes and ion transport. Currently, environmentally-realistic Me(O)NP concentrations are unlikely to cause significant adverse acute health problems, however sub-lethal effects e.g. oxidative stresses have been noted in many organisms, often deriving from dissolution of Ag, Cu or Zn ions, and this could result in chronic health impacts. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  18. Spectroscopical properties of organic/metal nanohybrids.

    PubMed

    Dellepiane, Giovanna; Cuniberti, Carla; Alloisio, Marina; Demartini, Anna

    2010-03-28

    The aim of our work was to prepare stable nanohybrids of controlled size and shape consisting of a noble metal core decorated with polydiacetylenes (PDAs). Due to the combination of the outstanding linear and nonlinear optical properties of the polydiacetylenic chains with the electromagnetic field-enhancing capability of metal nanostructures, these novel composites can find potential application in different fields. In particular, the different colours exhibited by PDAs in relation to the chemical nature of the monomer and the polymerization procedure, as well as in response to environmental perturbations, make them excellent materials for the fabrication of sensing devices. On the basis of our previous work on PDA self-assembled monolayers on flat metal surfaces, the results of which are briefly reported, we prepared differently-shaped gold and silver nanocores (spheres, cages) coated with various diacetylenic monomers having end-groups able to firmly anchor to the metal surface. These nanohybrids exhibit in aqueous colloidal solution an enhanced photochemical polymerization monitored step by step with UV-Vis and SERS techniques. It is shown that in these stable assemblies an intra-particle polymerization takes place and that the dominant PDA form is conditioned by the core size and geometry. While the nanoparticles are SERS active in the visible, the nanocages should be excellent SERS substrates from the visible to the near infrared regions.

  19. Metal interactions in carcinogenesis: enhancement, inhibition

    PubMed Central

    Nordberg, Gunnar F.; Andersen, Ole

    1981-01-01

    Metals constitute a fundamentally important part of the total human environment. Since human exposure often involves complex mixtures of metal compounds and, possibly, organic compounds which may be carcinogenic per se, interactions between these compounds may add significantly to human cancer risk. Our present knowledge about these kinds of interactions is very limited. The best investigated area is benzo(a)pyrene (BP)-metal oxide particle interactions in respiratory carcinogenesis in the hamster. Metal oxide particles were also shown to modify the carcinogenic effect of nitrosamines. Several reports describe experiments in which selenium compounds exerted a generally anticarcinogenic and antimutagenic activity. Inorganic arsenic compounds, which are accepted to be carcinogenic in man, have so far been negative in animal experiments except for one recent suggested report. Several authors have, however, suggested that these compounds may act as cocarcinogens due to their inhibition of DNA repair, although animal experiments to demonstrate a cocarcinogenic effect of arsenic compounds have been negative so far, except for one preliminary report. The concentration of zinc in the diet seemed to influence both transplanted tumor growth and the carcinogenicity of several organic compounds, and the possibility of a correlation between dietary zinc and certain cancer forms in man has been suggested. Protection against development of Leydigiomas usually induced by cadmium injection was afforded by simultaneous injection of zinc salts. Nickel carcinogenesis has been reported to be antagonized by manganese, and synergism between Ni and organic carcinogens, e.g. BP, has been demonstrated. There is no firm evidence that lead may be a cocarcinogen, although some limited experimental evidence is available. Oxidizing agents have been demonstrated to increase, and reducing agents to antagonize, the mutagenic effect of chromium compounds in vitro. The content of carcinogenic and

  20. Silver nanorod structures for metal enhanced fluorescence

    NASA Astrophysics Data System (ADS)

    Badshah, Mohsin Ali; Lu, Xun; Ju, Jonghyun; Kim, Seok-min

    2016-09-01

    Fluorescence based detection is a commonly used methodology in biotechnology and medical diagnostics. Metalenhanced fluorescence (MEF) becomes a promising strategy to improve the sensitivity of fluorescence detection, where fluorophores coupling with surface plasmon on metallic structures results fluorescence enhancement. To apply the MEF methodology in real medical diagnostics, especially for protein or DNA microarray detection, a large area (e.g., slide glass, 75 × 25 mm2) with uniform metallic nanostructures is required. In this study, we fabricated a large area MEF substrates using oblique angle deposition (OAD), which is a single step, inexpensive large area fabrication method of nanostructures. To optimize the morphological effect, Ag-nanorods with various lengths were fabricated on the conventional slide glass substrates. Streptavidin-Cy5 dissolved in buffer solution with different concentration (100ng/ml 100μg/ml) were applied to MEF substrates using a pipette, and the fluorescence signals were measured. The enhancement factor increased with the increase in length of Ag-nanorods and maximum enhancement factor 91x was obtained from Ag-nanorods 750nm length compare to bare glass due to higher surface Plasmon effect.

  1. Purification of metal-organic framework materials

    DOEpatents

    Farha, Omar K.; Hupp, Joseph T.

    2015-06-30

    A method of purification of a solid mixture of a metal-organic framework (MOF) material and an unwanted second material by disposing the solid mixture in a liquid separation medium having a density that lies between those of the wanted MOF material and the unwanted material, whereby the solid mixture separates by density differences into a fraction of wanted MOF material and another fraction of unwanted material.

  2. Purification of metal-organic framework materials

    SciTech Connect

    Farha, Omar K.; Hupp, Joseph T.

    2012-12-04

    A method of purification of a solid mixture of a metal-organic framework (MOF) material and an unwanted second material by disposing the solid mixture in a liquid separation medium having a density that lies between those of the wanted MOF material and the unwanted material, whereby the solid mixture separates by density differences into a fraction of wanted MOF material and another fraction of unwanted material.

  3. Metallization with generic metallo-organic inks

    NASA Technical Reports Server (NTRS)

    Vest, G. M.

    1983-01-01

    The use and fabrication of metallo-organic films are discussed. Metallo-organic compounds are ones in which a metal is linked to a long chain carbon ligand through a hetero atom such as O, S, N, P or As. Films formed by the thermal decomposition of these metallo-organics are called MOD films. In order that the products of decomposition contain only CO2, H2O, and in rare cases nitrogen compounds, and to avoid S containing products, the use of a set of metallo-organic compounds for ink fabrication where the linking hetero atom was oxygen was pioneered. These links were made from commercially available carboxylates, or synthesized from commonly available reagents. The processing is described and the molecular design criteria are given. The particular carboxylates or amine carboxylates selected were the octoates or neodecanoates, and they are described.

  4. Metal Vinylidenes as Catalytic Species in Organic Reactions

    PubMed Central

    McClory, Andrew

    2008-01-01

    Organic vinylidene species have found limited use in organic synthesis due to their inaccessibility. In contrast, metal vinylidenes are much more stable, and may be readily accessed through transition metal activation of terminal alkynes. These electrophilic species may be trapped by a number of nucleophiles. Additionally, metal vinylidenes can participate in pericyclic reactions and processes involving migration of a metal ligand to the vinylidene species. This review addresses the reactions and applications of metal vinylidenes in organic synthesis. PMID:18172846

  5. Cascade reactions catalyzed by metal organic frameworks.

    PubMed

    Dhakshinamoorthy, Amarajothi; Garcia, Hermenegildo

    2014-09-01

    Cascade or tandem reactions where two or more individual reactions are carried out in one pot constitute a clear example of process intensification, targeting the maximization of spatial and temporal productivity with mobilization of minimum resources. In the case of catalytic reactions, cascade processes require bi-/multifunctional catalysts that contain different classes of active sites. Herein, we show that the features and properties of metal-organic frameworks (MOFs) make these solids very appropriate materials for the development of catalysts for cascade reactions. Due to composition and structure, MOFs can incorporate different types of sites at the metal nodes, organic linkers, or at the empty internal pores, allowing the flexible design and synthesis of multifunctional catalysts. After some introductory sections on the relevance of cascade reactions from the point of view of competitiveness, sustainability, and environmental friendliness, the main part of the text provides a comprehensive review of the literature reporting the use of MOFs as heterogeneous catalysts for cascade reactions including those that combine in different ways acid/base, oxidation/reduction, and metal-organic centers. The final section summarizes the current state of the art, indicating that the development of a first commercial synthesis of a high-added-value fine chemical will be a crucial milestone in this area.

  6. Impact of metals on the biodegradation of organic pollutants.

    PubMed Central

    Sandrin, Todd R; Maier, Raina M

    2003-01-01

    Forty percent of hazardous waste sites in the United States are co-contaminated with organic and metal pollutants. Data from both aerobic and anaerobic systems demonstrate that biodegradation of the organic component can be reduced by metal toxicity. Metal bioavailability, determined primarily by medium composition/soil type and pH, governs the extent to which metals affect biodegradation. Failure to consider bioavailability rather than total metal likely accounts for much of the enormous variability among reports of inhibitory concentrations of metals. Metals appear to affect organic biodegradation through impacting both the physiology and ecology of organic degrading microorganisms. Recent approaches to increasing organic biodegradation in the presence of metals involve reduction of metal bioavailability and include the use of metal-resistant bacteria, treatment additives, and clay minerals. The addition of divalent cations and adjustment of pH are additional strategies currently under investigation. PMID:12826480

  7. Effects of metals on chromosomes of higher organisms.

    PubMed

    Sharma, A; Talukder, G

    1987-01-01

    An analysis of the available data on the clastogenic effects of metals and their compounds on higher organisms indicates some general trends. Following chronic exposure to subtoxic doses, a decrease in mitotic frequency and an increase in the number of chromosomal abnormalities are observed. These effects are usually directly proportional to the dose applied and the duration of treatment within the threshold limits. Recovery after acute treatment is inversely related to the dosage. The ultimate expression of the effects depends on certain factors, including the mode and vehicle of administration; the form administered; the test system used; the rate of detoxification, distribution, and retention in the different tissues; and interaction with foreign and endogenous substances as well as the mode of action with the biological macromolecules. In mammals, the clastogenic activity of the metals within each vertical group of the periodic table is directly proportional to the increase in atomic weight, electropositivity, and solubility of the metallic cations in water and lipids, except for Li and Ba. This pattern of inherent cytotoxicity increases with successive periods in the horizontal level. It is enhanced by the formation of covalent and coordinate covalent complexes by heavy metals with the biological macromolecules. In plants, the solubility of the metals in water is of much greater importance. The degree of dissociation of metallic salts and the rate of absorption affect significantly the frequency of chromosomal aberrations. In assessing the effects of environmental metal pollution, the presence of other metals and toxic chemicals and the level of nutrition should be taken into account, since in nature, metals occur in combination and these factors modify the cytotoxic effects to a significant extent.

  8. Increased Thermal Conductivity in Metal-Organic Heat Carrier Nanofluids.

    PubMed

    Nandasiri, Manjula I; Liu, Jian; McGrail, B Peter; Jenks, Jeromy; Schaef, Herbert T; Shutthanandan, Vaithiyalingam; Nie, Zimin; Martin, Paul F; Nune, Satish K

    2016-06-15

    Metal-organic heat carriers (MOHCs) are recently developed nanofluids containing metal-organic framework (MOF) nanoparticles dispersed in various base fluids including refrigerants (R245Fa) and methanol. Here, we report the synthesis and characterization of MOHCs containing nanoMIL-101(Cr) and graphene oxide (GO) in an effort to improve the thermo-physical properties of various base fluids. MOHC/GO nanocomposites showed enhanced surface area, porosity, and nitrogen adsorption compared with the intrinsic nanoMIL-101(Cr) and the properties depended on the amount of GO added. MIL-101(Cr)/GO in methanol exhibited a significant increase in the thermal conductivity (by approximately 50%) relative to that of the intrinsic nanoMIL-101(Cr) in methanol. The thermal conductivity of the base fluid (methanol) was increased by about 20%. The increase in the thermal conductivity of nanoMIL-101(Cr) MOHCs due to GO functionalization is explained using a classical Maxwell model.

  9. Increased Thermal Conductivity in Metal-Organic Heat Carrier Nanofluids

    PubMed Central

    Nandasiri, Manjula I.; Liu, Jian; McGrail, B. Peter; Jenks, Jeromy; Schaef, Herbert T.; Shutthanandan, Vaithiyalingam; Nie, Zimin; Martin, Paul F.; Nune, Satish K.

    2016-01-01

    Metal-organic heat carriers (MOHCs) are recently developed nanofluids containing metal-organic framework (MOF) nanoparticles dispersed in various base fluids including refrigerants (R245Fa) and methanol. Here, we report the synthesis and characterization of MOHCs containing nanoMIL-101(Cr) and graphene oxide (GO) in an effort to improve the thermo-physical properties of various base fluids. MOHC/GO nanocomposites showed enhanced surface area, porosity, and nitrogen adsorption compared with the intrinsic nanoMIL-101(Cr) and the properties depended on the amount of GO added. MIL-101(Cr)/GO in methanol exhibited a significant increase in the thermal conductivity (by approximately 50%) relative to that of the intrinsic nanoMIL-101(Cr) in methanol. The thermal conductivity of the base fluid (methanol) was increased by about 20%. The increase in the thermal conductivity of nanoMIL-101(Cr) MOHCs due to GO functionalization is explained using a classical Maxwell model. PMID:27302196

  10. Increased Thermal Conductivity in Metal-Organic Heat Carrier Nanofluids

    NASA Astrophysics Data System (ADS)

    Nandasiri, Manjula I.; Liu, Jian; McGrail, B. Peter; Jenks, Jeromy; Schaef, Herbert T.; Shutthanandan, Vaithiyalingam; Nie, Zimin; Martin, Paul F.; Nune, Satish K.

    2016-06-01

    Metal-organic heat carriers (MOHCs) are recently developed nanofluids containing metal-organic framework (MOF) nanoparticles dispersed in various base fluids including refrigerants (R245Fa) and methanol. Here, we report the synthesis and characterization of MOHCs containing nanoMIL-101(Cr) and graphene oxide (GO) in an effort to improve the thermo-physical properties of various base fluids. MOHC/GO nanocomposites showed enhanced surface area, porosity, and nitrogen adsorption compared with the intrinsic nanoMIL-101(Cr) and the properties depended on the amount of GO added. MIL-101(Cr)/GO in methanol exhibited a significant increase in the thermal conductivity (by approximately 50%) relative to that of the intrinsic nanoMIL-101(Cr) in methanol. The thermal conductivity of the base fluid (methanol) was increased by about 20%. The increase in the thermal conductivity of nanoMIL-101(Cr) MOHCs due to GO functionalization is explained using a classical Maxwell model.

  11. Increased Thermal Conductivity in Metal-Organic Heat Carrier Nanofluids

    SciTech Connect

    Nandasiri, Manjula I.; Liu, Jian; McGrail, B. Peter; Jenks, Jeromy WJ; Schaef, Herbert T.; Shutthanandan, V.; Nie, Zimin; Martin, Paul F.; Nune, Satish K.

    2016-06-15

    Metal organic heat carriers (MOHCs) are recently developed nanofluids containing metal organic framework (MOF) nanoparticles dispersed in various base fluids including refrigerants (R245Fa) and methanol. MOHCs utilize the MOF properties to improve the thermo-physical properties of base fluids. Here, we report the synthesis and characterization of MOHCs containing nanoMIL-101(Cr) and graphene oxide (GO) in an effort to improve the thermo-physical properties of various base fluids. MOHC containing MIL-101(Cr)/GO nanocomposites showed enhanced surface area, porosity, and nitrogen adsorption compared with the intrinsic nano MIL-101(Cr) and the properties depend on the amount of GO added. Powder X-ray diffraction (PXRD) confirmed the preserved crystallinity of MIL-101(Cr) in all nanocomposites with the absence of any unreacted GO. Scanning electron microscopy images confirmed the presence of near spherical MIL-101(Cr) nanoparticles in the range of 40-80 nm in diameter. MOHC nanofluids containing MIL-101(Cr)/GO in methanol exhibited significant enhancement in the thermal conductivity (by approxi-mately 50%) relative to that of the intrinsic nano MIL-101(Cr) in methanol. The thermal conductivity of base fluid (methanol) was enhanced by about 20 %. The enhancement in the thermal conductivity of nanoMIL-101(Cr) MOHCs due to graphene oxide functionalization is explained using a classical Maxwell model.

  12. Metal-organic frameworks as selectivity regulators for hydrogenation reactions

    NASA Astrophysics Data System (ADS)

    Zhao, Meiting; Yuan, Kuo; Wang, Yun; Li, Guodong; Guo, Jun; Gu, Lin; Hu, Wenping; Zhao, Huijun; Tang, Zhiyong

    2016-11-01

    Owing to the limited availability of natural sources, the widespread demand of the flavouring, perfume and pharmaceutical industries for unsaturated alcohols is met by producing them from α,β-unsaturated aldehydes, through the selective hydrogenation of the carbon-oxygen group (in preference to the carbon-carbon group). However, developing effective catalysts for this transformation is challenging, because hydrogenation of the carbon-carbon group is thermodynamically favoured. This difficulty is particularly relevant for one major category of heterogeneous catalyst: metal nanoparticles supported on metal oxides. These systems are generally incapable of significantly enhancing the selectivity towards thermodynamically unfavoured reactions, because only the edges of nanoparticles that are in direct contact with the metal-oxide support possess selective catalytic properties; most of the exposed nanoparticle surfaces do not. This has inspired the use of metal-organic frameworks (MOFs) to encapsulate metal nanoparticles within their layers or inside their channels, to influence the activity of the entire nanoparticle surface while maintaining efficient reactant and product transport owing to the porous nature of the material. Here we show that MOFs can also serve as effective selectivity regulators for the hydrogenation of α,β-unsaturated aldehydes. Sandwiching platinum nanoparticles between an inner core and an outer shell composed of an MOF with metal nodes of Fe3+, Cr3+ or both (known as MIL-101; refs 19, 20, 21) results in stable catalysts that convert a range of α,β-unsaturated aldehydes with high efficiency and with significantly enhanced selectivity towards unsaturated alcohols. Calculations reveal that preferential interaction of MOF metal sites with the carbon-oxygen rather than the carbon-carbon group renders hydrogenation of the former by the embedded platinum nanoparticles a thermodynamically favoured reaction. We anticipate that our basic design

  13. Capturing snapshots of post-synthetic metallation chemistry in metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Bloch, Witold M.; Burgun, Alexandre; Coghlan, Campbell J.; Lee, Richmond; Coote, Michelle L.; Doonan, Christian J.; Sumby, Christopher J.

    2014-10-01

    Post-synthetic metallation is employed strategically to imbue metal-organic frameworks (MOFs) with enhanced performance characteristics. However, obtaining precise structural information for metal-centred reactions that take place within the pores of these materials has remained an elusive goal, because of issues with high symmetry in certain MOFs, lower initial crystallinity for some chemically robust MOFs, and the reduction in crystallinity that can result from carrying out post-synthetic reactions on parent crystals. Here, we report a new three-dimensional MOF possessing pore cavities that are lined with vacant di-pyrazole groups poised for post-synthetic metallation. These metallations occur quantitatively without appreciable loss of crystallinity, thereby enabling examination of the products by single-crystal X-ray diffraction. To illustrate the potential of this platform to garner fundamental insight into metal-catalysed reactions in porous solids we use single-crystal X-ray diffraction studies to structurally elucidate the reaction products of consecutive oxidative addition and methyl migration steps that occur within the pores of the Rh-metallated MOF, 1·[Rh(CO)2][Rh(CO)2Cl2].

  14. Raman spectroscopy: Enhanced by organic surfaces

    NASA Astrophysics Data System (ADS)

    Lombardi, John R.

    2017-09-01

    Nanostructured films of organic semiconductors are now shown to enhance the Raman signal of probe molecules, paving the way to the realization of substrates for Raman spectroscopy with molecular selectivity.

  15. Advanced Organic Ligands for Protecting Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, Jonathan Ka-Wing

    Organic monolayer protected metal nanoparticles have been utilized in many different fields such as catalysis, drug delivery, and sensor chemistry. However, these nanomaterials are prone to increase in size consequently losing its function at the nanoscale. The stability these nanoparticles have been a great interest of research. This thesis focuses on the synthesis of a novel cross-linkable ligand for the protection of metal nanoparticles. Chapter 1 reviews key concepts of nanoparticles, its usefulness in applications, some of the stabilizing strategies employed, and the scope of the thesis project. Chapter 2 describes the synthetic attempts and optimization of the novel cross-linkable ligand. In addition, its characterization data is also included. Section 2.8 also highlights another fully synthesized novel hydrophobic ligand. Chapter 3 contains the summary of the work and closing remarks. Future works is also included to describe the prospects of the synthesis of the novel ligand. Chapter 4 entails the experimental data and supplementary information.

  16. Lanthanide Metal-Organic Framework Materials

    NASA Astrophysics Data System (ADS)

    Hsieh, Ping-Yen; Green, Mark A.; Briber, Robert M.

    2009-03-01

    A series of lanthanide metal-organic framework materials (MOF) with variable organic linkages including benzene-dicarboxylic acid (BDC); 1,3,5-benzene-tricarboxylic acid (BTC); and 1,3,5-tris(4-carboxyphenyl)benzene (BTB) have been synthesized. The low density and high porosity of MOFs make them candidates molecular sieve or hydrogen storage materials. The crystal structures have been determined using a combination of single crystal X-ray diffractometer and synchrotron powder X-ray diffraction work. Holmium with the BDC ligand material (Ho-BDC) crystallizes in a monoclinic C2/c space group, with lattice parameters of a = 17.06 å, b = 10.67 å, c = 10.57 å, b = 96.12^o. The crystal structure of Ho-BTC is in tetragonal P 41 2 2 space group and Ho-BTB is in a triclinic P-1 space group. A comprehensive examination of Ho-MOF with different ligands by x-ray and thermogravimetric analysis shows that there is a stable nanoporous structure for dehydrated Ho-BTC up to 250^oC. The same phenomenon is not observed in the Ho-BDC and Ho-BTB materials. The collapsed structure with BDC and BTB indicates the stability of dehydrated samples is strongly related to the interactions between the metal and the organic linkers.

  17. Multifunctional Metal-Organic Frameworks for Photocatalysis.

    PubMed

    Wang, Sibo; Wang, Xinchen

    2015-07-01

    Metal-organic frameworks (MOFs) have attracted significant research attention in diverse areas due to their unique physical and chemical characteristics that allow their innovative application in various research fields. Recently, the application of MOFs in heterogeneous photocatalysis for water splitting, CO2 reduction, and organic transformation have emerged, aiming at providing alternative solutions to address the world-wide energy and environmental problems by taking advantage of the unique porous structure together with ample physicochemical properties of the metal centers and organic ligands in MOFs. In this review, the latest progress in MOF-involved solar-to-chemical energy conversion reactions are summarized according to their different roles in the photoredox chemical systems, e.g., photocatalysts, co-catalysts, and hosts. The achieved progress and existing problems are evaluated and proposed, and the opportunities and challenges of MOFs and their related materials for their advanced development in photocatalysis are discussed and anticipated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Nanoantennas for enhanced light trapping in transparent organic solar cells

    NASA Astrophysics Data System (ADS)

    Voroshilov, P. M.; Simovski, C. R.; Belov, P. A.

    2014-12-01

    We propose a light-trapping structure offering a significant enhancement of photovoltaic absorption in transparent organic solar cells operating at infrared, while the visible light transmission keeps sufficiently high. The main mechanism of light trapping is related with the excitation of collective oscillations of the metal nanoantenna arrays, characterized by advantageous field distribution in the volume of the solar cell. It allows more than triple increase in infrared photovoltaic absorption.

  19. DEMONSTRATION BULLETIN: METAL-ENHANCED ABIOTIC DEGRADATION TECHNOLOGY - ENVIROMETAL TECHNOLOGIES, INC.

    EPA Science Inventory

    EnviroMetal Technologies, Inc. (ETI), of Guelph, ON, Canada, has developed the metal-enhanced abiotic degradation technology to treat halogenated volatile organic compounds (VOC) in water. A reactive, zero-valent, granular iron medium causes reductive dehalogenation of VOCs yield...

  20. DEMONSTRATION BULLETIN: METAL-ENHANCED ABIOTIC DEGRADATION TECHNOLOGY - ENVIROMETAL TECHNOLOGIES, INC.

    EPA Science Inventory

    EnviroMetal Technologies, Inc. (ETI), of Guelph, ON, Canada, has developed the metal-enhanced abiotic degradation technology to treat halogenated volatile organic compounds (VOC) in water. A reactive, zero-valent, granular iron medium causes reductive dehalogenation of VOCs yield...

  1. Metal-doped organic gels and method thereof

    DOEpatents

    Satcher, Jr., Joe H.; Baumann, Theodore F.

    2003-09-02

    Disclosed herein is a sol-gel polymerization process for synthesizing metal-doped organic gels. The process polymerizes metal salts of hydroxylated benzenes or hydroxylated benzene derivatives with alkyl or aryl aldehydes to form metal-doped, wet, organic gels. The gels can then be dried by supercritical solvent extraction to form metal-doped aerogels or by evaporation to form metal-doped xerogels. The aerogels and xerogels can then be pyrolyzed.

  2. Metal-doped organic gels and method thereof

    DOEpatents

    Satcher, Jr., Joe H.; Baumann, Theodore F.

    2007-10-23

    Disclosed herein is a sol-gel polymerization process for synthesizing metal-doped organic gels. The process polymerizes metal salts of hydroxylated benzenes or hydroxylated benzene derivatives with alkyl or aryl aldehydes to form metal-doped, wet, organic gels. The gels can then be dried by supercritical solvent extraction to form metal-doped aerogels or by evaporation to form metal-doped xerogels. The aerogels and xerogels can then be pyrolyzed.

  3. Deposition of CdS nanoparticles on MIL-53(Fe) metal-organic framework with enhanced photocatalytic degradation of RhB under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Hu, Longxing; Deng, Guihua; Lu, Wencong; Pang, Siwei; Hu, Xing

    2017-07-01

    A novel composite, CdS/MIL-53(Fe), was successfully fabricated via a facile solvothermal method and characterized with XRD, SEM, TEM, XPS, FT-IR and UV-vis DRS. The results showed that the fabrication was able to result in a good dispersion of CdS nanoparticles onto MIL-53(Fe). The photocatalytic activities of the as-synthesized composite were investigated through the degradation of Rhodamine B (RhB) in water under visible light irradiation. It was found that the composite prepared at the mass ratio of CdS to MIL-53(Fe) of 1.5:1 displayed the highest photocatalytic activity. An approximately 92.5% of photocatalytic degradation of RhB was achieved at 0.5 g/L of 1.5-CdS/MIL dosage, 10 mg/L of initial RhB concentration and 23 °C of reaction temperature under visible light irradiation. The RhB photocatalytic degradation followed well the first-order kinetics equation and the increased catalyst dosage and optimal initial RhB concentration were responsible for the enhanced photocatalytic degradation. Quenching tests revealed that the predominant free radicals in the CdS/MIL-(53)-RhBaq-visible light system was O2-rad ; nevertheless, h+ and rad OH also contributed to a certain degree. The enhanced photocatalytic performance was ascribed to the formation of heterojunction structure between CdS and MIL-53(Fe) which significantly suppressed the recombination of photogenerated electron-hole pairs. Moreover, the reusability of 1.5-CdS/MIL composite was also studied.

  4. Metal-organic frameworks in chromatography.

    PubMed

    Yusuf, Kareem; Aqel, Ahmad; ALOthman, Zeid

    2014-06-27

    Metal-organic frameworks (MOFs) emerged approximately two decades ago and are the youngest class of porous materials. Despite their short existence, MOFs are finding applications in a variety of fields because of their outstanding chemical and physical properties. This review article focuses on the applications of MOFs in chromatography, including high-performance liquid chromatography (HPLC), gas chromatography (GC), and other chromatographic techniques. The use of MOFs in chromatography has already had a significant impact; however, the utilisation of MOFs in chromatography is still less common than other applications, and the number of MOF materials explored in chromatography applications is limited. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Hydrogen storage in metal-organic frameworks.

    PubMed

    Hu, Yun Hang; Zhang, Lei

    2010-05-25

    Metal-organic frameworks (MOFs) are highly attractive materials because of their ultra-high surface areas, simple preparation approaches, designable structures, and potential applications. In the past several years, MOFs have attracted worldwide attention in the area of hydrogen energy, particularly for hydrogen storage. In this review, the recent progress of hydrogen storage in MOFs is presented. The relationships between hydrogen capacities and structures of MOFs are evaluated, with emphasis on the roles of surface area and pore size. The interaction mechanism between H(2) and MOFs is discussed. The challenges to obtain a high hydrogen capacity at ambient temperature are explored.

  6. Biomimicry in metal-organic materials

    SciTech Connect

    Zhang, MW; Gu, ZY; Bosch, M; Perry, Z; Zhou, HC

    2015-06-15

    Nature has evolved a great number of biological molecules which serve as excellent constructional or functional units for metal-organic materials (MOMs). Even though the study of biomimetic MOMs is still at its embryonic stage, considerable progress has been made in the past few years. In this critical review, we will highlight the recent advances in the design, development and application of biomimetic MOMs, and illustrate how the incorporation of biological components into MOMs could further enrich their structural and functional diversity. More importantly, this review will provide a systematic overview of different methods for rational design of MOMs with biomimetic features. Published by Elsevier B.V.

  7. Nanoporous carbohydrate metal-organic frameworks.

    PubMed

    Forgan, Ross S; Smaldone, Ronald A; Gassensmith, Jeremiah J; Furukawa, Hiroyasu; Cordes, David B; Li, Qiaowei; Wilmer, Christopher E; Botros, Youssry Y; Snurr, Randall Q; Slawin, Alexandra M Z; Stoddart, J Fraser

    2012-01-11

    The binding of alkali and alkaline earth metal cations by macrocyclic and diazamacrobicyclic polyethers, composed of ordered arrays of hard oxygen (and nitrogen) donor atoms, underpinned the development of host-guest supramolecular chemistry in the 1970s and 1980s. The arrangement of -OCCO- and -OCCN- chelating units in these preorganized receptors, including, but not limited to, crown ethers and cryptands, is responsible for the very high binding constants observed for their complexes with Group IA and IIA cations. The cyclodextrins (CDs), cyclic oligosaccharides derived microbiologically from starch, also display this -OCCO- bidentate motif on both their primary and secondary faces. The self-assembly, in aqueous alcohol, of infinite networks of extended structures, which have been termed CD-MOFs, wherein γ-cyclodextrin (γ-CD) is linked by coordination to Group IA and IIA metal cations to form metal-organic frameworks (MOFs), is reported. CD-MOF-1 and CD-MOF-2, prepared on the gram-scale from KOH and RbOH, respectively, form body-centered cubic arrangements of (γ-CD)(6) cubes linked by eight-coordinate alkali metal cations. These cubic CD-MOFs are (i) stable to the removal of solvents, (ii) permanently porous, with surface areas of ~1200 m(2) g(-1), and (iii) capable of storing gases and small molecules within their pores. The fact that the -OCCO- moieties of γ-CD are not prearranged in a manner conducive to encapsulating single metal cations has led to our isolating other infinite frameworks, with different topologies, from salts of Na(+), Cs(+), and Sr(2+). This lack of preorganization is expressed emphatically in the case of Cs(+), where two polymorphs assemble under identical conditions. CD-MOF-3 has the cubic topology observed for CD-MOFs 1 and 2, while CD-MOF-4 displays a channel structure wherein γ-CD tori are perfectly stacked in one dimension in a manner reminiscent of the structures of some γ-CD solvates, but with added crystal stability imparted

  8. Dependence of metal-enhanced fluorescence on surface roughness

    NASA Astrophysics Data System (ADS)

    François, Alexandre; Sciacca, Beniamino; Zuber, Agnieszka; Klantsataya, Elizaveta; Monro, Tanya M.

    2014-03-01

    Metal Enhanced Fluorescence (MEF) takes advantage of the coupling between surface plasmons, in either a metallic thin film or metallic nanoparticles, and fluorophores located in proximity of the metal, yielding an increase of the fluorophore emission. While MEF has been widely studied on metallic nanoparticles with the emphasis on creating brighter fluorescent labels, planar surfaces have not benefitted from the same attention. Here we investigate the influence of the surface roughness of a thin metallic film on the fluorescence enhancement. 50nm thick silver films were deposited on glass slides using either thermal evaporation with different evaporation currents or an electroless plating method based on the Tollens reaction to vary the surface roughness. Multiple layers of positively and negatively charged polyelectrolytes were deposited on top of the metallic coating to map out the enhancement factor as function of the gap between the metallic coating and fluorophore molecules covalently bound to the last polyelectrolyte layer. We show that fluorescence is enhanced by the presence of the metallic film, and in particular that the enhancement increases by a factor 3 to 40 for roughness ranging from 3 nm to 8 nm. Although these enhancement factors are modest compared to the enhancement produced by complex metallic nanoparticles or nano-patterned metallic thin films, the thin films used here are capable of supporting a plasmonic wave and offer the possibility of combining different techniques, such as surface plasmon resonance (with its higher refractive index sensitivity compared to localized plasmons) and MEF within a single device.

  9. Fly ash enhanced metal removal process

    SciTech Connect

    Nonavinakere, S.; Reed, B.E.

    1995-12-31

    The primary objective of the study was to evaluate the effectiveness of fly ashes from local thermal power plants in the removal of cadmium, nickel, chromium, lead, and copper from aqueous waste streams. Physical and chemical characteristics of fly ashes were determined, batch isotherm studies were conducted. A practical application of using fly ash in treating spent electroless nickel (EN) plating baths by modified conventional precipitation or solid enhanced metal removal process (SEMR) was investigated. In addition to nickel the EN baths also contains completing agents such as ammonium citrate and succinic acid reducing agents such as phosphate and hypophosphite. SEMR experiments were conducted at different pHs, fly ash type and concentrations, and settling times.

  10. Enhanced proton conductivity of Nafion hybrid membrane under different humidities by incorporating metal-organic frameworks with high phytic acid loading.

    PubMed

    Li, Zhen; He, Guangwei; Zhang, Bei; Cao, Ying; Wu, Hong; Jiang, Zhongyi; Tiantian, Zhou

    2014-06-25

    In this study, phytic acid (myo-inositol hexaphosphonic acid) was first immobilized by MIL101 via vacuum-assisted impregnation method. The obtained phytic@MIL101 was then utilized as a novel filler to incorporate into Nafion to fabricate hybrid proton exchange membrane for application in PEMFC under different relative humidities (RHs), especially under low RHs. High loading and uniform dispersion of phytic acid in MIL 101(Cr) were achieved as demonstrated by ICP, FT-IR, XPS, and EDS-mapping. The phytic@MIL101 was dispersed homogeneously in the Nafion matrix when the filler content was less than 12%. Hybrid membranes were evaluated by proton conductivity, mechanical property, thermal stability, and so forth. Remarkably, the Nafion/phytic@MIL hybrid membranes showed high proton conductivity at different RHs, especially under low RHs, which was up to 0.0608 S cm(-1) and 7.63 × 10(-4) S cm(-1) at 57.4% RH and 10.5% RH (2.8 and 11.0 times higher than that of pristine membrane), respectively. Moreover, the mechanical property of Nafion/phtic@MIL hybrid membranes was substantially enhanced and the thermal stability of membranes was well preserved.

  11. Surface enhanced Raman scattering with metal nanoshells

    NASA Astrophysics Data System (ADS)

    Jackson, Joseph Bryan

    A systematic investigation of surface enhanced Raman scattering (SERS) was performed using metal nanoshells as the substrate. Nanoshells are a dielectric sphere coated with a thin metal shell, which have a well understood, geometrically tunable plasmon resonance. This tunability allows for the engineering of the optical near field for SERS. A simple model connecting the nanoshell electromagnetic near field at the incident frequency to that at the Raman shifted frequency is discussed. This theory is compared to the measured SERS response of the nonresonant molecule para-mercaptoaniline (pMA) adsorbed on silver and gold nanoshells. Using a solution of silver nanoshells, at an excitation wavelength of 1064 nm enhancements on the order of 106 to 108 were observed. Accounting for reabsorption of the Raman scattered light as it traverses the solution suggests enhancements of 1012. To mitigate the reabsorption, film geometries were investigated. For film measurements a 782 nm excitation laser was used. The SERS response of a dense film of silver nanoshells followed the calculated single nanoshell response of the nanoshells whose plasmon resonance was tuned near the excitation wavelength. In contrast, for nanoshells blue shifted from the excitation laser, the film Raman response followed an estimated dimer response. The Raman response as a function of nanoshell density was studied using films of gold nanoshells dispersed on the surface of polyvinylpyridine (PVP) coated glass slides. A linear dependence of the Raman modes on the nanoshell density was observed confirming that the single nanoshell plasmon dominates the SERS response. The SERS enhancements for nanoshell films calculated by direct comparison to an unenhanced measurement were on the order of 10 10 to 1012. The Raman response as a function of incident intensity was measured for dense silver nanoshell films. An optical pumping model allowing for stimulation of the Raman emission is proposed. Using this model, an

  12. Chemical enhancement of metallized zinc anode performance

    SciTech Connect

    Bennett, J.

    1998-12-31

    Galvanic current delivered to reinforced concrete by a metallized zinc anode was studied relative to the humidity of its environment and periodic direct wetting. Current decreased quickly at low humidity to values unlikely to meet accepted cathodic protection criteria, but could be easily restored by direct wetting of the anode. Thirteen chemicals were screened for their ability to enhance galvanic current. Such chemicals, when applied to the exterior surface of the anode, are easily transported by capillary action to the anode-concrete interface where they serve to maintain the interface conductive and the zinc electrochemically active. The most effective chemicals were potassium and lithium bromide, acetate, chloride and nitrate, which increased galvanic current by a factor of 2--15, depending on relative humidity and chloride contamination of the concrete. This new technique is expected to greatly expand the number of concrete structures which can be protected by simple galvanic cathodic protection, The use of lithium-based chemicals together with metallized zinc anode is also proposed for mitigation of existing problems due to ASR. In this case, lithium which prevents or inhibits expansion due to ASR can be readily injected into the concrete. A new process, electrochemical maintenance of concrete (EMC), is also proposed to benefit reinforced concrete structures suffering from chloride-induced corrosion.

  13. Increasing the Stability of Metal-Organic Frameworks

    DOE PAGES

    Bosch, Mathieu; Zhang, Muwei; Zhou, Hong-Cai

    2014-01-01

    Metal-organic frameworks (MOFs) are a new category of advanced porous materials undergoing study by many researchers for their vast variety of both novel structures and potentially useful properties arising from them. Their high porosities, tunable structures, and convenient process of introducing both customizable functional groups and unsaturated metal centers have afforded excellent gas sorption and separation ability, catalytic activity, luminescent properties, and more. However, the robustness and reactivity of a given framework are largely dependent on its metal-ligand interactions, where the metal-containing clusters are often vulnerable to ligand substitution by water or other nucleophiles, meaning that the frameworks may collapsemore » upon exposure even to moist air. Other frameworks may collapse upon thermal or vacuum treatment or simply over time. This instability limits the practical uses of many MOFs. In order to further enhance the stability of the framework, many different approaches, such as the utilization of high-valence metal ions or nitrogen-donor ligands, were recently investigated. This review details the efforts of both our research group and others to synthesize MOFs possessing drastically increased chemical and thermal stability, in addition to exemplary performance for catalysis, gas sorption, and separation.« less

  14. Thermodynamics of metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Wu, Di; Navrotsky, Alexandra

    2015-03-01

    Although there have been extensive studies over the past decade in the synthesis and application of metal-organic frameworks (MOFs), investigation of their thermodynamic stability and of the energetics of guest-host interactions has been much more limited. This review summarizes recent progress in experimental (calorimetric) determination of the thermodynamics of MOF materials. The enthalpies of MOFs relative to dense phase assemblages suggest only modest metastability, with a general increase of enthalpy with increasing molar volume, which becomes less pronounced at higher porosity. The energy landscape of nanoporous materials (inorganic and hybrid) consists of a pair of parallel patterns within a fairly narrow range of metastability of 5-30 kJ per mole of tetrahedra in zeolites and mesoporous silicas or per mole of metal in MOFs. Thus strong thermodynamic instability does not seem to limit framework formation. There are strong interactions within the chemisorption range for small molecule-MOF interactions with defined chemical binding at the metal centers or other specific locations. Coexistence of surface binding and confinement can lead to much stronger guest-host interactions.

  15. Thermodynamics of metal-organic frameworks

    SciTech Connect

    Wu, Di; Navrotsky, Alexandra

    2015-03-15

    Although there have been extensive studies over the past decade in the synthesis and application of metal-organic frameworks (MOFs), investigation of their thermodynamic stability and of the energetics of guest–host interactions has been much more limited. This review summarizes recent progress in experimental (calorimetric) determination of the thermodynamics of MOF materials. The enthalpies of MOFs relative to dense phase assemblages suggest only modest metastability, with a general increase of enthalpy with increasing molar volume, which becomes less pronounced at higher porosity. The energy landscape of nanoporous materials (inorganic and hybrid) consists of a pair of parallel patterns within a fairly narrow range of metastability of 5–30 kJ per mole of tetrahedra in zeolites and mesoporous silicas or per mole of metal in MOFs. Thus strong thermodynamic instability does not seem to limit framework formation. There are strong interactions within the chemisorption range for small molecule–MOF interactions with defined chemical binding at the metal centers or other specific locations. Coexistence of surface binding and confinement can lead to much stronger guest–host interactions. - Graphical abstract: Energy landscape of inorganic and hybrid porous materials. - Highlights: • Thermochemical data on various MOF structures were experimentally determined. • MOFs are moderately unstable relative to their dense phase assemblage. • Overall energetic landscape of porous materials was revealed. • Guest–host interactions in MOFs were evaluated directly using calorimetry. • Confinement effect and defined chemical binding lead to strong interactions.

  16. Glycine post-synthetic modification of MIL-53(Fe) metal-organic framework with enhanced and stable peroxidase-like activity for sensitive glucose biosensing.

    PubMed

    Dong, Wenfei; Yang, Liaoyuan; Huang, Yuming

    2017-05-15

    A facile and rapid post-synthetic strategy was proposed to prepare a glycine functionalized MIL-53(Fe), namely glycine-MIL-53(Fe), by a simple mixing of water dispersible MIL-53(Fe) and glycine. The FT-IR, SEM, XRD and zeta potential were used to characterize the glycine-MIL-53(Fe). The result showed that glycine post-synthetic modification of MIL-53(Fe) did not change in the morphology and crystal structure of MIL-53(Fe). Interestingly, compared with MIL-53(Fe), the glycine-MIL-53(Fe) exhibits an enhanced peroxidase-like activity, which could catalyze the oxidation of TMB by H2O2 to produce an intensive color reaction. Kinetic analysis indicated that the Km of glycine-MIL-53(Fe) for TMB was one-tenth of that of MIL-53(Fe). The glycine-MIL-53(Fe) as peroxidase mimetic displays better stability under alkaline or acidic conditions than MIL-53(Fe). The good performance of glycine-MIL-53(Fe) over MIL-53(Fe) may be attributed to the increase of affinity between TMB and the glycine-MIL-53(Fe). With these characteristics, a simple and sensitive method was developed for the detection of H2O2 and glucose. The linear detection range for H2O2 is 0.10-10μM with a detection limit of 49nM, and glucose could be linearly detected in the range from 0.25 to 10μM with a detection limit of 0.13μM. The proposed method was successfully used for glucose detection in human serum samples.

  17. Hydrogen Storage in Metal-Organic Frameworks

    SciTech Connect

    Omar M. Yaghi

    2012-04-26

    Conventional storage of large amounts of hydrogen in its molecular form is difficult and expensive because it requires employing either extremely high pressure gas or very low temperature liquid. Because of the importance of hydrogen as a fuel, the DOE has set system targets for hydrogen storage of gravimetric (5.5 wt%) and volumetric (40 g L-1) densities to be achieved by 2015. Given that these are system goals, a practical material will need to have higher capacity when the weight of the tank and associated cooling or regeneration system is considered. The size and weight of these components will vary substantially depending on whether the material operates by a chemisorption or physisorption mechanism. In the latter case, metal-organic frameworks (MOFs) have recently been identified as promising adsorbents for hydrogen storage, although little data is available for their sorption behavior. This grant was focused on the study of MOFs with these specific objectives. (1) To examine the effects of functionalization, catenation, and variation of the metal oxide and organic linkers on the low-pressure hydrogen adsorption properties of MOFs. (2) To develop a strategy for producing MOFs with high surface area and porosity to reduce the dead space and increase the hydrogen storage capacity per unit volume. (3) To functionalize MOFs by post synthetic functionalization with metals to improve the adsorption enthalpy of hydrogen for the room temperature hydrogen storage. This effort demonstrated the importance of open metal sites to improve the adsorption enthalpy by the systematic study, and this is also the origin of the new strategy, which termed isoreticular functionalization and metalation. However, a large pore volume is still a prerequisite feature. Based on our principle to design highly porous MOFs, guest-free MOFs with ultrahigh porosity have been experimentally synthesized. MOF-210, whose BET surface area is 6240 m2 g-1 (the highest among porous solids), takes up

  18. Stepwise Synthesis of Metal-Organic Frameworks.

    PubMed

    Bosch, Mathieu; Yuan, Shuai; Rutledge, William; Zhou, Hong-Cai

    2017-03-28

    Metal-organic frameworks (MOFs) are a category of porous materials that offer unparalleled control over their surface areas (demonstrated as higher than for any other material), pore characteristics, and functionalization. This allows them to be customized for exceptional performance in a wide variety of applications, most commonly including gas storage and separation, drug delivery, luminescence, or heterogeneous catalysis. In order to optimize biomimicry, controlled separations and storage of small molecules, and detailed testing of structure-property relationships, one major goal of MOF research is "rational design" or "pore engineering", or precise control of the placement of multiple functional groups in pores of chosen sizes and shapes. MOF crystal growth can be controlled through judicious design of stepwise synthetic routes, which can also allow functionalization of MOFs in ways that were previously synthetically inaccessible. Organic chemists have developed a library of powerful techniques over the last century, allowing the total synthesis and detailed customization of complex molecules. Our hypothesis is that total synthesis is also possible for customized porous materials, through the development of similar multistep techniques. This will enable the rational design of MOFs, which is a major goal of many researchers in the field. We have begun developing a library of stepwise synthetic techniques for MOFs, allowing the synthesis of ultrastable MOFs with multiple crystallographically ordered and customizable functional groups at controlled locations within the pores. In order to design MOFs with precise control over pore size and shape, stability, and the placement of multiple different functional groups within the pores at tunable distances from one another, we have concentrated on methods which allow us to circumvent the lack of control inherent to one-pot MOF crystallization. Kinetically tuned dimensional augmentation (KTDA) is an approach using

  19. Transition metal complexes supported on metal-organic frameworks for heterogeneous catalysts

    DOEpatents

    Farha, Omar K.; Hupp, Joseph T.; Delferro, Massimiliano; Klet, Rachel C.

    2017-02-07

    A robust mesoporous metal-organic framework comprising a hafnium-based metal-organic framework and a single-site zirconium-benzyl species is provided. The hafnium, zirconium-benzyl metal-organic framework is useful as a catalyst for the polymerization of an alkene.

  20. Thermodynamics of Metal-Organic Frameworks

    NASA Astrophysics Data System (ADS)

    Hughes, James Thomas

    Metal-Organic Frameworks (MOF) are crystalline nanoporous lattices constructed from the combination of cation and multi-dentate organic molecules. MOFs can display both chemical and thermal robustness while having large surface areas and pore volumes. In addition the modular composition of MOFs allows a degree of design and control of MOF structures. These unique physical properties have attracted wide interest and position MOFs to make meaningful contributions towards many applications, such as adsorption, catalysis, separation, and sensing. Despite the extensive investigative work over the last decade on MOF materials, the initial synthesis is still done by trial and error. Of the identified structures some MOFs are robust while others are fragile. It is unclear what role thermodynamics plays in the formation energies of MOFs and guest molecules interactions within the pores. Better understanding of thermochemical properties of MOFs is critical if MOF synthesis is to obtain true predictive design. To address these questions aqueous solution calorimetry was performed on ten different frameworks in both the as-synthesized and activated state. To understand the structural energetics of MOFs, the heat of formation from dense states (metal oxide and protonated organic linkers) to the open MOF framework was measured. Chapter 2 discusses the new aqueous calorimetry methodology developed to measure the enthalpy of solution for hybrid materials. Chapters 3, 4 and 5 detail the enthalpies of formation from their dense states of the frameworks: (MOF-5, ZIF-zni, ZIF-1, ZIF-3, ZIF-4, ZIF-7, ZIF-8, ZIF-9 and Cu-HKUST-1). These chapters also compare the MOF heat of formation energetics to those of zeolites, zeotypes and mesoporous silica materials. Finding that MOFs are metastable with respect to their dense states (metal oxide and protonated organic), following the current destabilization trend of the main group porous materials. The thermochemical effect of solvent on the MOF

  1. Metal-organic framework materials with ultrahigh surface areas

    DOEpatents

    Farha, Omar K.; Hupp, Joseph T.; Wilmer, Christopher E.; Eryazici, Ibrahim; Snurr, Randall Q.; Gomez-Gualdron, Diego A.; Borah, Bhaskarjyoti

    2015-12-22

    A metal organic framework (MOF) material including a Brunauer-Emmett-Teller (BET) surface area greater than 7,010 m.sup.2/g. Also a metal organic framework (MOF) material including hexa-carboxylated linkers including alkyne bond. Also a metal organic framework (MOF) material including three types of cuboctahedron cages fused to provide continuous channels. Also a method of making a metal organic framework (MOF) material including saponifying hexaester precursors having alkyne bonds to form a plurality of hexa-carboxylated linkers including alkyne bonds and performing a solvothermal reaction with the plurality of hexa-carboxylated linkers and one or more metal containing compounds to form the MOF material.

  2. Dispersion enhanced metal/zeolite catalysts

    DOEpatents

    Sachtler, W.M.H.; Tzou, M.S.; Jiang, H.J.

    1987-03-31

    Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

  3. Dispersion enhanced metal/zeolite catalysts

    DOEpatents

    Sachtler, Wolfgang M. H.; Tzou, Ming-Shin; Jiang, Hui-Jong

    1987-01-01

    Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

  4. Metal salt catalysts for enhancing hydrogen spillover

    DOEpatents

    Yang, Ralph T; Wang, Yuhe

    2013-04-23

    A composition for hydrogen storage includes a receptor, a hydrogen dissociating metal doped on the receptor, and a metal salt doped on the receptor. The hydrogen dissociating metal is configured to spill over hydrogen to the receptor, and the metal salt is configured to increase a rate of the spill over of the hydrogen to the receptor.

  5. Chelation: Harnessing and Enhancing Heavy Metal Detoxification—A Review

    PubMed Central

    Sears, Margaret E.

    2013-01-01

    Toxic metals such as arsenic, cadmium, lead, and mercury are ubiquitous, have no beneficial role in human homeostasis, and contribute to noncommunicable chronic diseases. While novel drug targets for chronic disease are eagerly sought, potentially helpful agents that aid in detoxification of toxic elements, chelators, have largely been restricted to overt acute poisoning. Chelation, that is multiple coordination bonds between organic molecules and metals, is very common in the body and at the heart of enzymes with a metal cofactor such as copper or zinc. Peptides glutathione and metallothionein chelate both essential and toxic elements as they are sequestered, transported, and excreted. Enhancing natural chelation detoxification pathways, as well as use of pharmaceutical chelators against heavy metals are reviewed. Historical adverse outcomes with chelators, lessons learned in the art of using them, and successes using chelation to ameliorate renal, cardiovascular, and neurological conditions highlight the need for renewed attention to simple, safe, inexpensive interventions that offer potential to stem the tide of debilitating, expensive chronic disease. PMID:23690738

  6. A Microporous Metal-Organic Framework with Lewis Basic Nitrogen Sites for High C2H2 Storage and Significantly Enhanced C2H2/CO2 Separation at Ambient Conditions.

    PubMed

    Wen, Hui-Min; Wang, Huizhen; Li, Bin; Cui, Yuanjing; Wang, Hailong; Qian, Guodong; Chen, Banglin

    2016-08-01

    A novel metal-organic framework (MOF), [Cu2L(H2O)2]·7DMF·4H2O [ZJU-40; H4L = 5,5'-(pyrazine-2,5-diyl)diisophthalic acid], with Lewis basic nitrogen sites has been constructed and structurally characterized. Owing to the combined features of high porosity, moderate pore sizes, and immobilized Lewis basic nitrogen sites, the activated ZJU-40a exhibits the second-highest gravimetric C2H2 uptake of 216 cm(3) g(-1) (at 298 K and 1 bar) among all of the reported MOFs so far. This value is not only much higher than that of the isoreticular NOTT-101a (184 cm(3) g(-1)), but also superior to those of two very promising MOFs, known as HKUST-1 (201 cm(3) g(-1)) and Co-MOF-74 (197 cm(3) g(-1)). Interestingly, the immobilized nitrogen sites in ZJU-40a have nearly no effect on the CO2 uptake, so ZJU-40a adsorbs a similar amount of CO2 (87 cm(3) g(-1)) compared with NOTT-101a (84 cm(3) g(-1)) at 298 K and 1 bar. As a result, ZJU-40a shows significantly enhanced adsorption selectivity for C2H2/CO2 separation (17-11.5) at ambient temperature compared to that of NOTT-101a (8-9), leading to a superior MOF material for highly selective C2H2/CO2 separation.

  7. Enhanced optical properties of InAs/InAlGaAs/InP quantum dots grown by metal-organic chemical vapor deposition using a double-cap technique

    NASA Astrophysics Data System (ADS)

    Shi, Bei; Lau, Kei May

    2016-01-01

    The effects of a double-cap procedure on the optical properties of an InAs/InAlGaAs quantum dots (QDs) system grown by metal-organic chemical vapor deposition (MOCVD) have been investigated by atomic force microscopy (AFM) and room temperature photoluminescence (RT-PL) spectroscopy. An optimized QD growth condition has been achieved, with an areal density of 4.6×1010 cm-2. It was found that the thickness and lattice constant of the high temperature second cap layer (SCL) were crucial for improving the integrated PL intensity and line-width of the 1.55 μm emission from the InAs/InAlGaAs QD system grown on a semi-insulating InP (100) substrate. With fine-tuned SCL thickness and lattice constant, the optical performance of the five-stack QDs was enhanced. The improvements can be attributed to the smooth growth front, observed from the AFM images, and the well-balanced stress engineering.

  8. Surface-Plasmon Enhanced Transparent Electrodes in Organic Photovoltaics

    SciTech Connect

    Reilly III, T. H.; van de Lagemaat, J.; Tenent, R. C.; Morfa, A. J.; Rowlen, K. L.

    2008-01-01

    Random silver nanohole films were created through colloidal lithography techniques and metal vapor deposition. The transparent electrodes were characterized by uv-visible spectroscopy and incorporated into an organic solar cell. The test cells were evaluated for solar power-conversion efficiency and incident photon-to-current conversion efficiency. The incident photon-to-current conversion efficiency spectra displayed evidence that a nanohole film with 92 nm diameter holes induces surface-plasmon-enhanced photoconversion. The nanohole silver films demonstrate a promising route to removing the indium tin oxide transparent electrode that is ubiquitous in organic optoelectronics.

  9. Heavy metals and arsenic fixation into freshwater organic matter under Gammarus pulex L. influence.

    PubMed

    Schaller, Joerg; Mkandawire, Martin; Gert Dudel, E

    2010-07-01

    Organic sediments are a main sink for metal pollutants in aquatic systems. However, factors that make sediments a sink of metals and metalloids are still not clear. Consequently, we investigate the role of invertebrate shredders (Gammarus pulex L.) on quality of metal and arsenic fixation into organic partitions of sediment in the course of litter decay with laboratory microcosm experiments. During the decomposition of leaf litter, G. pulex significantly facilitated the development of small particles of organic matter. The capacity of metal fixation was significantly higher in smaller particles than leaf litter and litter residuals. Thus, G. pulex enhanced metal fixation into the organic partition of sediments by virtue of increasing the amount smaller particles in the aquatic system. Furthermore, invertebrates have a significant effect on formation of dissolved organic matter and remobilization of cobalt, molybdenum and cesium, but no significant effect on remobilization of all other measured elements.

  10. Homochiral helical metal-organic frameworks of group 1 metals.

    PubMed

    Reger, Daniel L; Leitner, Andrew; Smith, Mark D; Tran, T Thao; Halasyamani, P Shiv

    2013-09-03

    The reactions of (S)-2-(1,8-naphthalimido)propanoic acid (HL(ala)) and (S)-2-(1,8-naphthalimido)-3-hydroxypropanoic acid (HL(ser)), protonated forms of ligands that contain a carboxylate donor group, an enantiopure chiral center, and a 1,8-naphthalimide π···π stacking supramolecular tecton and in the case of HL(ser) an alcohol functional group, with the appropriate alkali metal hydroxide followed by a variety of crystallization methods leads to the formation of crystalline K(L(ala))(MeOH) (1), K(L(ala))(H2O) (2), Na(L(ala))(H2O) (3), KL(ser) (4), CsL(ser) (5), and CsL(ala) (6). Each of these new complexes has a solid state structure based on six-coordinate metals linked into homochiral helical rod secondary building unit (SBU) central cores. In addition to the bonding of the carboxylate and solvent (in the case of L(ser) the ligand alcohol) to the metals, both oxygens on the 1,8-naphthalimide act as donor groups. One naphthalimide oxygen bonds to the same helical rod SBU as the carboxylate group of that ligand forming a chelate ring. The other naphthalimide oxygen bonds to adjacent SBUs. In complexes 1-3, this inter-rod link has a square arrangement bonding four other rods forming a three-dimensional enantiopure metal-organic framework (MOF) structure, whereas in 4-6 this link has a linear arrangement bonding two other rods forming a two-dimensional, sheet structure. In the latter case, the third dimension is supported exclusively by interdigitated π···π stacking interactions of the naphthalimide supramolecular tecton, forming enantiopure supramolecular MOF solids. Compounds 1-3 lose the coordinated solvent when heating above 100 °C. For 1, the polycrystalline powder reverts to 1 only by recrystallization from methanol, whereas compounds 2 and 3 undergo gas/solid, single-crystal to single-crystal transformations to form dehydrated compounds 2* and 3*, and rehydration occurs when crystals of these new complexes are left out in air. The reversible single

  11. Hydrogen Storage in Metal-Organic Frameworks

    SciTech Connect

    Long, Jeffrey R.

    2016-04-28

    The design and characterization of new materials for hydrogen storage is an important area of research, as the ability to store hydrogen at lower pressures and higher temperatures than currently feasible would lower operating costs for small hydrogen fuel cell vehicles. In particular, metal-organic frameworks (MOFs) represent promising materials for use in storing hydrogen in this capacity. MOFs are highly porous, three-dimensional crystalline solids that are formed via linkages between metal ions (e.g., iron, nickel, and zinc) and organic molecules. MOFs can store hydrogen via strong adsorptive interactions between the gas molecules and the pores of the framework, providing a high surface area for gas adsorption and thus the opportunity to store hydrogen at significantly lower pressures than with current technologies. By lowering the energy required for hydrogen storage, these materials hold promise in rendering hydrogen a more viable fuel for motor vehicles, which is a highly desirable outcome given the clean nature of hydrogen fuel cells (water is the only byproduct of combustion) and the current state of global climate change resulting from the combustion of fossil fuels. The work presented in this report is the result of collaborative efforts between researchers at Lawrence Berkeley National Lab (LBNL), the National Institute of Standards and Technology (NIST), and General Motors Corporation (GM) to discover novel MOFs promising for H2 storage and characterize their properties. Described herein are several new framework systems with improved gravimetric and volumetric capacity to strongly bind H2 at temperatures relevant for vehicle storage. These materials were rigorously characterized using neutron diffraction, to determine the precise binding locations of hydrogen within the frameworks, and high-pressure H2 adsorption measurements, to provide a comprehensive picture of H2 adsorption at all relevant pressures. A

  12. Plasmonic enhancement of light trapping into organic solar cells

    NASA Astrophysics Data System (ADS)

    Nguyen, Bich Ha; Hieu Nguyen, Van; Vu, Dinh Lam

    2015-12-01

    The present work is devoted to the review of the methods to improve light trapping into polymer solar cells. After a discussion on the important role of the improvement of the light-trapping technique in the fabrication of solar cells by applying the plasmonic enhancement effect, we review the results of the study on this topic, which were obtained mainly during recent years. The light-trapping nanostructures usually comprised the following basic elements: antireflection coating, randomly distributed or symmetric-periodic monolayers of metallic spherical nanoparticles (NPs), metallic NPs with different shapes, spherical NPs with core-shell structure, nanovoids, plasmonic metallic grating, grating organic active layer, grating indium tin oxide (ITO) layer, dielectric grating, photonic structure, and plasmonic cavity with subwavelength hole array. Each light-trapping nanostructure may use either one or two of the above-mentioned basic elements.

  13. Phosphine Gas Adsorption in a Series of Metal-Organic Frameworks.

    PubMed

    Weston, Mitchell H; Morris, William; Siu, Paul W; Hoover, William J; Cho, David; Richardson, Rachelle K; Farha, Omar K

    2015-09-08

    For the first time, phosphine adsorption has been evaluated in a series of metal-organic frameworks (MOFs). Open-metal coordination sites were found to significantly enhance the ability of MOFs to adsorb highly toxic phosphine gas, with the identity of the open-metal site also modulating the amount of gas adsorbed. The MOFs studied outperform activated carbon, a commonly used material to capture phosphine.

  14. Redox-promoted associative assembly of metal-organic materials.

    PubMed

    Glavinović, Martin; Qi, Feng; Katsenis, Athanassios D; Friščić, Tomislav; Lumb, Jean-Philip

    2016-01-01

    We develop an associative synthesis of metal-organic materials that combines solid-state metal oxidation and coordination-driven self-assembly into a one-step, waste-free transformation. The methodology hinges on the unique reactivity of ortho-quinones, which we introduce as versatile oxidants for mechanochemical synthesis. Our strategy opens a previously unexplored route to paramagnetic metal-organic materials from elementary metals.

  15. Metal-adeninate vertices for the construction of an exceptionally porous metal-organic framework.

    PubMed

    An, Jihyun; Farha, Omar K; Hupp, Joseph T; Pohl, Ehmke; Yeh, Joanne I; Rosi, Nathaniel L

    2012-01-03

    Metal-organic frameworks comprising metal-carboxylate cluster vertices and long, branched organic linkers are the most porous materials known, and therefore have attracted tremendous attention for many applications, including gas storage, separations, catalysis and drug delivery. To increase metal-organic framework porosity, the size and complexity of linkers has increased. Here we present a promising alternative strategy for constructing mesoporous metal-organic frameworks that addresses the size of the vertex rather than the length of the organic linker. This approach uses large metal-biomolecule clusters, in particular zinc-adeninate building units, as vertices to construct bio-MOF-100, an exclusively mesoporous metal-organic framework. Bio-MOF-100 exhibits a high surface area (4,300 m(2) g(-1)), one of the lowest crystal densities (0.302 g cm(-3)) and the largest metal-organic framework pore volume reported to date (4.3 cm(3) g(-1)).

  16. Method of enhancing selective isotope desorption from metals

    DOEpatents

    Knize, R.J.; Cecchi, J.L.

    1983-07-26

    This invention relates generally to the field of gas desorption from metals; and, more particularly, to a method of enhancing the selective desorption of a particular isotope of a gas from metals. Enhanced selective desorption is especially useful in the operation of fusion devices.

  17. Metal-Organic Heat Carrier Nanofluids

    SciTech Connect

    McGrail, B. Peter; Thallapally, Praveen K.; Blanchard, Jeremy; Nune, Satish K.; Jenks, Jeromy WJ; Dang, Liem X.

    2013-09-01

    Nanofluids, dispersions of metal or oxide nanoparticles in a base working fluid, are being intensively studied due to improvements they offer in thermal properties of the working fluid. However, these benefits have been erratically demonstrated and proven impacts on thermal conductivity are modest and well described from long-established effective medium theory. In this paper, we describe a new class of metal-organic heat carrier (MOHC) nanofluid that offers potential for a larger performance boost in thermal vapor-liquid compression cycles. MOHCs are nanophase porous coordination solids designed to reversibly uptake the working fluid molecules in which the MOHCs are suspended. Additional heat can be extracted in a heat exchanger or solar collector from the endothermic enthalpy of desorption, which is then released as the nanofluid transits through a power generating device such as a turboexpander. Calculations for an R123 MOHC nanofluid indicated potential for up to 15% increase in power output. Capillary tube experiments show that liquid-vapor transitions occur without nanoparticle deposition on the tube walls provided entrance Reynolds number exceeds approximately 100.

  18. An Electrically Switchable Metal-Organic Framework

    NASA Astrophysics Data System (ADS)

    Fernandez, Carlos A.; Martin, Paul C.; Schaef, Todd; Bowden, Mark E.; Thallapally, Praveen K.; Dang, Liem; Xu, Wu; Chen, Xilin; McGrail, B. Peter

    2014-08-01

    Crystalline metal organic framework (MOF) materials containing interconnected porosity can be chemically modified to promote stimulus-driven (light, magnetic or electric fields) structural transformations that can be used in a number of devices. Innovative research strategies are now focused on understanding the role of chemical bond manipulation to reversibly alter the free volume in such structures of critical importance for electro-catalysis, molecular electronics, energy storage technologies, sensor devices and smart membranes. In this letter, we study the mechanism for which an electrically switchable MOF composed of Cu(TCNQ) (TCNQ = 7,7,8,8-tetracyanoquinodimethane) transitions from a high-resistance state to a conducting state in a reversible fashion by an applied potential. The actual mechanism for this reversible electrical switching is still not understood even though a number of reports are available describing the application of electric-field-induced switching of Cu(TCNQ) in device fabrication.

  19. Electrically Conductive Porous Metal-Organic Frameworks.

    PubMed

    Sun, Lei; Campbell, Michael G; Dincă, Mircea

    2016-03-07

    Owing to their outstanding structural, chemical, and functional diversity, metal-organic frameworks (MOFs) have attracted considerable attention over the last two decades in a variety of energy-related applications. Notably missing among these, until recently, were applications that required good charge transport coexisting with porosity and high surface area. Although most MOFs are electrical insulators, several materials in this class have recently demonstrated excellent electrical conductivity and high charge mobility. Herein we review the synthetic and electronic design strategies that have been employed thus far for producing frameworks with permanent porosity and long-range charge transport properties. In addition, key experiments that have been employed to demonstrate electrical transport, as well as selected applications for this subclass of MOFs, will be discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Proton-Conducting Metal-Organic Frameworks

    NASA Astrophysics Data System (ADS)

    Ford, Jamie; Simmons, Jason; Yildirim, Taner

    2010-03-01

    Vehicles powered by polymer electrolyte membrane (PEM) fuel cells are an exciting alternative to current fossil fuel technology. The membranes in these cells serve as both charge transporter, ferrying protons from the anode to the cathode, and gas diffusion barrier, preventing the backflow of oxygen to the anode. Currently, hydrated sulfonated polymers are the preferred material for these membranes. The presence of water, however, limits the operating temperature to 100 C, reducing the electrode kinetics and CO tolerance of the entire system. In an effort to increase the efficiency and operating temperature of these fuel cells, we are investigating the proton conductivity of new host/guest materials based on metal-organic frameworks (MOFs) loaded with imidazole. These thermally stable frameworks provide well-defined pores that accommodate imidazole networks and form proton-conducting pathways. Here, we will present the structure and proton dynamics of these materials as elucidated by elastic and inelastic neutron scattering measurements.

  1. Stimulus-responsive metal-organic frameworks.

    PubMed

    Nagarkar, Sanjog S; Desai, Aamod V; Ghosh, Sujit K

    2014-09-01

    Materials that can recognize the changes in their local environment and respond by altering their inherent physical and/or chemical properties are strong candidates for future "smart" technology materials. Metal-organic frameworks (MOFs) have attracted a great deal of attention in recent years owing to their designable architecture, host-guest chemistry, and softness as porous materials. Despite this fact, studies on the tuning of the properties of MOFs by external stimuli are still rare. This review highlights the recent developments in the field of stimulus-responsive MOFs or so-called smart MOFs. In particular, the various stimuli used and the utility of stimulus-responsive smart MOFs for various applications such as gas storage and separation, sensing, clean energy, catalysis, molecular motors, and biomedical applications are highlighted by using representative examples. Future directions in the developments of stimulus-responsive smart MOFs and their applications are proposed from a personal perspective.

  2. An Electrically Switchable Metal-Organic Framework

    SciTech Connect

    Fernandez, Carlos A.; Martin, Paul F.; Schaef, Herbert T.; Bowden, Mark E.; Thallapally, Praveen K.; Dang, Liem X.; Xu, Wu; Chen, Xilin; McGrail, B. Peter

    2014-08-19

    Crystalline metal organic framework (MOF) materials containing interconnected porosity can be chemically modified to promote stimulus-driven (light, magnetic or electric fields) structural transformations that can be used in a number of devices. Innovative research strategies are now focused on understanding the role of chemical bond manipulation to reversibly alter the free volume in such structures of critical importance for electro-catalysis, molecular electronics, energy storage technologies, sensor devices and smart membranes. In this letter, we study the mechanism for which an electrically switchable MOF composed of Cu(TCNQ) (TCNQ 5 7,7,8,8-tetracyanoquinodimethane) transitions from a high-resistance state to a conducting state in a reversible fashion by an applied potential. The actual mechanism for this reversible electrical switching is still not understood even though a number of reports are available describing the application of electric-field-induced switching of Cu(TCNQ) in device fabrication.

  3. An Electrically Switchable Metal-Organic Framework

    SciTech Connect

    Fernandez, CA; Martin, PC; Schaef, T; Bowden, ME; Thallapally, PK; Dang, L; Xu, W; Chen, XL; McGrail, BP

    2014-08-19

    Crystalline metal organic framework (MOF) materials containing interconnected porosity can be chemically modified to promote stimulus-driven (light, magnetic or electric fields) structural transformations that can be used in a number of devices. Innovative research strategies are now focused on understanding the role of chemical bond manipulation to reversibly alter the free volume in such structures of critical importance for electro-catalysis, molecular electronics, energy storage technologies, sensor devices and smart membranes. In this letter, we study the mechanism for which an electrically switchable MOF composed of Cu(TCNQ) (TCNQ = 7,7,8,8-tetracyanoquinodimethane) transitions from a high-resistance state to a conducting state in a reversible fashion by an applied potential. The actual mechanism for this reversible electrical switching is still not understood even though a number of reports are available describing the application of electric-field-induced switching of Cu(TCNQ) in device fabrication.

  4. An Electrically Switchable Metal-Organic Framework

    PubMed Central

    Fernandez, Carlos A.; Martin, Paul C.; Schaef, Todd; Bowden, Mark E.; Thallapally, Praveen K.; Dang, Liem; Xu, Wu; Chen, Xilin; McGrail, B. Peter

    2014-01-01

    Crystalline metal organic framework (MOF) materials containing interconnected porosity can be chemically modified to promote stimulus-driven (light, magnetic or electric fields) structural transformations that can be used in a number of devices. Innovative research strategies are now focused on understanding the role of chemical bond manipulation to reversibly alter the free volume in such structures of critical importance for electro-catalysis, molecular electronics, energy storage technologies, sensor devices and smart membranes. In this letter, we study the mechanism for which an electrically switchable MOF composed of Cu(TCNQ) (TCNQ = 7,7,8,8-tetracyanoquinodimethane) transitions from a high-resistance state to a conducting state in a reversible fashion by an applied potential. The actual mechanism for this reversible electrical switching is still not understood even though a number of reports are available describing the application of electric-field-induced switching of Cu(TCNQ) in device fabrication. PMID:25135307

  5. Recent applications of metal-organic frameworks in sample pretreatment.

    PubMed

    Wang, Yonghua; Rui, Min; Lu, Guanghua

    2017-06-19

    Metal-organic frameworks are promising materials in diverse analytical applications especially in sample pretreatment by virtue of their diverse structure topology, tunable pore size, permanent nanoscale porosity, high surface area, and good thermostability. According to hydrostability, metal-organic frameworks are divided into moisture-sensitive and water-stable types. In the actual applications, both kinds of metal-organic frameworks are usually engineered into hybrid composites containing magnetite, silicon dioxide, graphene, or directly carbonized to metal-organic frameworks derived carbon. These metal-organic frameworks based materials show good extraction performance to environmental pollutants. This review provides a critical overview of the applications of metal-organic frameworks and their composites in sample pretreatment modes, that is, solid-phase extraction, magnetic solid-phase extraction, micro-solid-phase extraction, solid-phase microextraction, and stir bar solid extraction. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Metallic Nanostructures for Enhanced Sensing and Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ahmed, Aftab

    The interaction of light and matter at nanoscale is the subject of study of this dissertation. Particularly, the coupling of light to surface plasmons and their applications in the fields of spectroscopy and sensing is the focus of this work. In terms of spectroscopy, the simple reason of using light to study the chemical structures of different materials is the fact that the energy of light lies in the range of vibrational and electronic transitions of matter. Further, the ability to squeeze light to subwavelength dimensions opens up new possibilities of designing nano-optical devices. In this work we explore surface plasmons for two major applications: (i) Directivity enhanced Raman spectroscopy and (ii) Chemical/biological sensing. Here a new enhancement phenomenon has been demonstrated experimentally in regards to Raman spectroscopy. Typically, Raman enhancement is considered in terms of local fields only. Here we show the use of directive nanoantennas to provide additional enhancement of two orders of magnitude. The nanoantenna design is optimal in the sense that almost all of the scattered light is coupled into the numerical aperture of the collecting lens. It is shown that the additional enhancement from directivity pushes the sensitivity to single molecule regime. Further, the out of plane radiation and simplicity of the design makes it an ideal candidate for use with typical commercial microscope setups. Extra ordinary transmission through nanohole arrays in metallic films is studied for refractive index sensing. Bulk resolution of 6x10 -7 is demonstrated by optimizing array dimensions, wavelength of operation, noise reduction and consideration of sensitivity of the detecting CCD camera. Self-assembled nanostructures are investigated for spectroscopic applications. Time dependent studies of nanorods assembled in end-to-end and side-by-side configurations are conducted. The end-to-end configuration results in higher local field enhancements whereas; the

  7. Ultrahigh porosity in metal-organic frameworks.

    PubMed

    Furukawa, Hiroyasu; Ko, Nakeun; Go, Yong Bok; Aratani, Naoki; Choi, Sang Beom; Choi, Eunwoo; Yazaydin, A Ozgür; Snurr, Randall Q; O'Keeffe, Michael; Kim, Jaheon; Yaghi, Omar M

    2010-07-23

    Crystalline solids with extended non-interpenetrating three-dimensional crystal structures were synthesized that support well-defined pores with internal diameters of up to 48 angstroms. The Zn4O(CO2)6 unit was joined with either one or two kinds of organic link, 4,4',4''-[benzene-1,3,5-triyl-tris(ethyne-2,1-diyl)]tribenzoate (BTE), 4,4',44''-[benzene-1,3,5-triyl-tris(benzene-4,1-diyl)]tribenzoate (BBC), 4,4',44''-benzene-1,3,5-triyl-tribenzoate (BTB)/2,6-naphthalenedicarboxylate (NDC), and BTE/biphenyl-4,4'-dicarboxylate (BPDC), to give four metal-organic frameworks (MOFs), MOF-180, -200, -205, and -210, respectively. Members of this series of MOFs show exceptional porosities and gas (hydrogen, methane, and carbon dioxide) uptake capacities. For example, MOF-210 has Brunauer-Emmett-Teller and Langmuir surface areas of 6240 and 10,400 square meters per gram, respectively, and a total carbon dioxide storage capacity of 2870 milligrams per gram. The volume-specific internal surface area of MOF-210 (2060 square meters per cubic centimeter) is equivalent to the outer surface of nanoparticles (3-nanometer cubes) and near the ultimate adsorption limit for solid materials.

  8. Enhancing metal-insulator-insulator-metal tunnel diodes via defect enhanced direct tunneling

    SciTech Connect

    Alimardani, Nasir; Conley, John F.

    2014-08-25

    Metal-insulator-insulator-metal tunnel diodes with dissimilar work function electrodes and nanolaminate Al{sub 2}O{sub 3}-Ta{sub 2}O{sub 5} bilayer tunnel barriers deposited by atomic layer deposition are investigated. This combination of high and low electron affinity insulators, each with different dominant conduction mechanisms (tunneling and Frenkel-Poole emission), results in improved low voltage asymmetry and non-linearity of current versus voltage behavior. These improvements are due to defect enhanced direct tunneling in which electrons transport across the Ta{sub 2}O{sub 5} via defect based conduction before tunneling directly through the Al{sub 2}O{sub 3}, effectively narrowing the tunnel barrier. Conduction through the device is dominated by tunneling, and operation is relatively insensitive to temperature.

  9. Induced metal redistribution and bioavailability enhancement in contaminated river sediment during in situ biogeochemical remediation.

    PubMed

    Liu, Tongzhou; Zhang, Zhen; Mao, Yanqing; Yan, Dickson Y S

    2016-04-01

    In situ sediment remediation using Ca(NO3)2 or CaO2 for odor mitigation and acid volatile sulfide (AVS) and organic pollutant (such as TPH and PAHs) removal was reported in many studies and fieldwork. Yet, the associated effects on metal mobilization and potential distortion in bioavailability were not well documented. In this study, contaminated river sediment was treated by Ca(NO3)2 and CaO2 in bench studies. Through the investigation of AVS removal, organic matter removal, the changes in sediment oxidation-reduction potential (ORP), microbial activity, and other indigenous parameters, the effects on metal bioavailability, bioaccessibility, and fraction redistribution in sediment were evaluated. The major mechanisms for sediment treated by Ca(NO3)2 and CaO2 are biostimulation with indigenous denitrifying bacteria and chemical oxidation, respectively. After applying Ca(NO3)2 and CaO2, the decreases of metal concentrations in the treated sediment were insignificant within a 35-day incubation period. However, the [SEMtot-AVS]/f OC increased near to the effective boundary of toxicity (100 μmol g(-1) organic carbon (OC)), indicating that both bioavailability and bioaccessibility of metals (Cu, Zn, and Ni) to benthic organisms are enhanced after remediation. Metals were found redistributed from relatively stable fractions (oxidizable and residual fractions) to weakly bound fractions (exchangeable and reducible fractions), and the results are in line with the enhanced metal bioavailability. Compared with Ca(NO3)2, CaO2 led to higher enhancement in metal bioavailability and bioaccessibility, and more significant metal redistribution, probably due to its stronger chemical reactive capacity to AVS and sediment organic matter. The reactions in CaO2-treated sediment would probably shift from physicochemical to biochemical heterotrophic oxidation for sediment organic matter degradation. Therefore, further investigation on the long-term metal redistribution and associated

  10. Metal Organic Framework Research: High Throughput Discovery of Robust Metal Organic Framework for CO2 Capture

    SciTech Connect

    2010-08-01

    IMPACCT Project: LBNL is developing a method for identifying the best metal organic frameworks for use in capturing CO2 from the flue gas of coal-fired power plants. Metal organic frameworks are porous, crystalline compounds that, based on their chemical structure, vary considerably in terms of their capacity to grab hold of passing CO2 molecules and their ability to withstand the harsh conditions found in the gas exhaust of coal-fired power plants. Owing primarily to their high tunability, metal organic frameworks can have an incredibly wide range of different chemical and physical properties, so identifying the best to use for CO2 capture and storage can be a difficult task. LBNL uses high-throughput instrumentation to analyze nearly 100 materials at a time, screening them for the characteristics that optimize their ability to selectively adsorb CO2 from coal exhaust. Their work will identify the most promising frameworks and accelerate their large-scale commercial development to benefit further research into reducing the cost of CO2 capture and storage.

  11. Broadband light absorption enhancement in polymer photovoltaics using metal nanowall gratings as transparent electrodes

    SciTech Connect

    Ye, Zhuo; Chaudhary, Sumit; Kuang, Ping; Ho, Kai-Ming

    2012-05-15

    The authors investigate light absorption in organic solar cells in which indium tin oxide (ITO) is replaced by a new metallic architecture (grating) as a transparent electrode. Different from typical metal nanowire gratings, our gratings consist of metal nanowalls with nanoscale footprint and (sub)microscale height [Adv. Mater. 23, 2469 (2011)], thus ensuring high optical transmittance and electrical conductivity. Simulations reveal that a broadband and polarization-insensitive light absorption enhancement is achieved via two mechanisms, when such silver nanowall gratings are employed in P3HT:PCBM based solar cells. Overall absorption enhanced by ~23% compared to a reference cell with ITO electrode.

  12. Approaches for enhanced phytoextraction of heavy metals.

    PubMed

    Bhargava, Atul; Carmona, Francisco F; Bhargava, Meenakshi; Srivastava, Shilpi

    2012-08-30

    The contamination of the environment with toxic metals has become a worldwide problem. Metal toxicity affects crop yields, soil biomass and fertility. Soils polluted with heavy metals pose a serious health hazard to humans as well as plants and animals, and often requires soil remediation practices. Phytoextraction refers to the uptake of contaminants from soil or water by plant roots and their translocation to any harvestable plant part. Phytoextraction has the potential to remove contaminants and promote long-term cleanup of soil or wastewater. The success of phytoextraction as a potential environmental cleanup technology depends on factors like metal availability for uptake, as well as plants ability to absorb and accumulate metals in aerial parts. Efforts are ongoing to understand the genetics and biochemistry of metal uptake, transport and storage in hyperaccumulator plants so as to be able to develop transgenic plants with improved phytoremediation capability. Many plant species are being investigated to determine their usefulness for phytoextraction, especially high biomass crops. The present review aims to give an updated version of information available with respect to metal tolerance and accumulation mechanisms in plants, as well as on the environmental and genetic factors affecting heavy metal uptake. The genetic tools of classical breeding and genetic engineering have opened the door to creation of 'remediation' cultivars. An overview is presented on the possible strategies for developing novel genotypes with increased metal accumulation and tolerance to toxicity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Method of enhancing selective isotope desorption from metals

    DOEpatents

    Knize, Randall J.; Cecchi, Joseph L.

    1984-01-01

    A method of enhancing the thermal desorption of a first isotope of a diatomic gas from a metal comprises the steps of (a) establishing a partial pressure of a second isotope of the diatomic gas in vicinity of the metal; heating the metal to a temperature such that the first isotope is desorbed from the metal; and reducing the partial pressure of the desorbed first isotope while maintaining the partial pressure of the second isotope substantially constant. The method is especially useful for enhancing the desorption of tritium from the Zr-Al getter in a plasma confinement device.

  14. The origin of the enhanced metallicity of satellite galaxies

    NASA Astrophysics Data System (ADS)

    Bahé, Yannick M.; Schaye, Joop; Crain, Robert A.; McCarthy, Ian G.; Bower, Richard G.; Theuns, Tom; McGee, Sean L.; Trayford, James W.

    2017-01-01

    Observations of galaxies in the local Universe have shown that both the ionized gas and the stars of satellites are more metal-rich than of equally massive centrals. To gain insight into the connection between this metallicity enhancement and other differences between centrals and satellites, such as their star formation rates, gas content, and growth history, we study the metallicities of >3600 galaxies with Mstar > 1010 M⊙ in the cosmological hydrodynamical EAGLE 100 Mpc `Reference' simulation, including ˜1500 in the vicinity of galaxy groups and clusters (M200 ≥ 1013 M⊙). The simulation predicts excess gas and stellar metallicities in satellites consistent with observations, except for stellar metallicities at Mstar ≲ 1010.2 M⊙ where the predicted excess is smaller than observed. The exact magnitude of the effect depends on galaxy selection, aperture, and on whether the metallicity is weighted by stellar mass or luminosity. The stellar metallicity excess in clusters is also sensitive to the efficiency scaling of star formation feedback. We identify stripping of low-metallicity gas from the galaxy outskirts, as well as suppression of metal-poor inflows towards the galaxy centre, as key drivers of the enhancement of gas metallicity. Stellar metallicities in satellites are higher than in the field as a direct consequence of the more metal-rich star-forming gas, whereas stripping of stars and suppressed stellar mass growth, as well as differences in accreted versus in situ star formation between satellites and the field, are of secondary importance.

  15. Modulate Organic-Metal Oxide Heterojunction via [1,6] Azafulleroid for Highly Efficient Organic Solar Cells.

    PubMed

    Li, Chang-Zhi; Huang, Jiang; Ju, Huanxin; Zang, Yue; Zhang, Jianyuan; Zhu, Junfa; Chen, Hongzheng; Jen, Alex K-Y

    2016-09-01

    By creating an effective π-orbital hybridization between the fullerene cage and the aromatic anchor (addend), the azafulleroid interfacial modifiers exhibit enhanced electronic coupling to the underneath metal oxides. High power conversion efficiency of 10.3% can be achieved in organic solar cells using open-cage phenyl C61 butyric acid methyl ester (PCBM)-modified zinc oxide layer.

  16. Metal-graphene-metal sandwich contacts for enhanced interface bonding and work function control.

    PubMed

    Gong, Cheng; Hinojos, David; Wang, Weichao; Nijem, Nour; Shan, Bin; Wallace, Robert M; Cho, Kyeongjae; Chabal, Yves J

    2012-06-26

    Only a small fraction of all available metals has been used as electrode materials for carbon-based devices due to metal-graphene interface debonding problems. We report an enhancement of the bonding energy of weakly interacting metals by using a metal-graphene-metal sandwich geometry, without sacrificing the intrinsic π-electron dispersions of graphene that is usually undermined by strong metal-graphene interface hybridization. This sandwich structure further makes it possible to effectively tune the doping of graphene with an appropriate selection of metals. Density functional theory calculations reveal that the strengthening of the interface interaction is ascribed to an enhancement of interface dipole-dipole interactions. Raman scattering studies of metal-graphene-copper sandwiches are used to validate the theoretically predicted tuning of graphene doping through sandwich structures.

  17. Metal oxide charge transport material doped with organic molecules

    DOEpatents

    Forrest, Stephen R.; Lassiter, Brian E.

    2016-08-30

    Doping metal oxide charge transport material with an organic molecule lowers electrical resistance while maintaining transparency and thus is optimal for use as charge transport materials in various organic optoelectronic devices such as organic photovoltaic devices and organic light emitting devices.

  18. Modeling plasmonic efficiency enhancement in organic photovoltaics.

    PubMed

    Taff, Y; Apter, B; Katz, E A; Efron, U

    2015-09-10

    Efficiency enhancement of bulk heterojunction (BHJ) organic solar cells by means of the plasmonic effect is investigated by using finite-difference time-domain (FDTD) optical simulations combined with analytical modeling of exciton dissociation and charge transport efficiencies. The proposed method provides an improved analysis of the cell performance compared to previous FDTD studies. The results of the simulations predict an 11.8% increase in the cell's short circuit current with the use of Ag nano-hexagons.

  19. Recent Advances in Carbon Capture with Metal-Organic Frameworks.

    PubMed

    Stylianou, Kyriakos C; Queen, Wendy L

    2015-01-01

    The escalating level of CO(2) in the atmosphere is one of the most critical environmental issues of our age. The carbon capture and storage from pilot test plants represents an option for reducing CO(2) emissions, however, the energy cost associated with post-combustion carbon capture process alone is ∼30% of the total energy generated by the power plant. Thus, the generation of carbon capture adsorbents with high uptake capacities, great separation performance and low cost is of paramount importance. Metal-organic frameworks are infinite networks of metal-containing nodes bridged by organic ligands through coordination bonds into porous extended structures and several reports have revealed that they are ideal candidates for the selective capture of CO(2). In this review we summarize recent advances related to the synthesis of porous MOFs and the latest strategies to enhance the CO(2) adsorption enthalpies and capacities at low-pressures, increase hydrolytic and mechanical stabilities, and improve the ease of regeneration. Although they show great promise for post-combustion carbon capture, there are still major challenges that must be overcome before they can be used for such a large-scale application.

  20. Metal-organic framework composites: from fundamentals to applications

    NASA Astrophysics Data System (ADS)

    Li, Shaozhou; Huo, Fengwei

    2015-04-01

    Metal-organic frameworks (MOFs) are a class of crystallized porous polymeric materials consisting of metal ions or clusters linked together by organic bridging ligands. Due to their permanent porosity, rich surface chemistry and tuneable pore sizes, MOFs have emerged as one type of important porous solid and have attracted intensive interests in catalysis, gas adsorption, separation and storage over the past two decades. When compared with pure MOFs, the combination of MOFs with functional species or matrix materials not only shows enhanced properties, but also broadens the applications of MOFs in new fields, such as bio-imaging, drug delivery and electrical catalysis, owing to the interactions of the functional species/matrix with the MOF structures. Although the synthesis, chemical modification and potential applications of MOFs have been reviewed previously, there is an increasing awareness on the synthesis and applications of their composites, which have rarely been reviewed. This review aims to fill this gap and discuss the fabrication, properties, and applications of MOF composites. The remaining challenges and future opportunities in this field, in terms of processing techniques, maximizing composite properties, and prospects for applications, have also been indicated.

  1. Quantum Efficiency Enhancement in CsI/Metal Photocathodes

    SciTech Connect

    Kong, Lingmei; Joly, Alan G.; Droubay, Timothy C.; Hess, Wayne P.

    2015-02-01

    High quantum efficiency enhancement is found for hybrid metal-insulator photocathodes consisting of thin films of CsI deposited on Cu(100), Ag(100), Au(111) and Au films irradiated by 266 nm laser pulses. Low work functions (near or below 2 eV) are observed following ultraviolet laser activation. Work functions are reduced by roughly 3 eV from that of clean metal surfaces. We discuss various mechanisms of quantum efficiency enhancement for alkali halide/metal photocathode systems and conclude that the large change in work function, due to Cs accumulation of Cs metal at the metal-alkali halide interface, is the dominant mechanism for quantum efficiency enhancement

  2. Integration of metal-organic frameworks into an electrochemical dielectric thin film for electronic applications

    PubMed Central

    Li, Wei-Jin; Liu, Juan; Sun, Zhi-Hua; Liu, Tian-Fu; Lü, Jian; Gao, Shui-Ying; He, Chao; Cao, Rong; Luo, Jun-Hua

    2016-01-01

    The integration of porous metal-organic frameworks onto the surface of materials, for use as functional devices, is currently emerging as a promising approach for gas sensing and flexible displays. However, research focused on potential applications in electronic devices is in its infancy. Here we present a facile strategy by which interpenetrated, crystalline metal-organic framework films are deposited onto conductive metal-plate anodes via in situ temperature-controlled electrochemical assembly. The nanostructure of the surface as well as the thickness and uniformity of the film are well controlled. More importantly, the resulting films exhibit enhanced dielectric properties compared to traditional inorganic or organic gate dielectrics. This study demonstrates the successful implementation of the rational design of metal-organic framework thin films on conductive supports with high-performance dielectric properties. PMID:27282348

  3. Integration of metal-organic frameworks into an electrochemical dielectric thin film for electronic applications

    NASA Astrophysics Data System (ADS)

    Li, Wei-Jin; Liu, Juan; Sun, Zhi-Hua; Liu, Tian-Fu; Lü, Jian; Gao, Shui-Ying; He, Chao; Cao, Rong; Luo, Jun-Hua

    2016-06-01

    The integration of porous metal-organic frameworks onto the surface of materials, for use as functional devices, is currently emerging as a promising approach for gas sensing and flexible displays. However, research focused on potential applications in electronic devices is in its infancy. Here we present a facile strategy by which interpenetrated, crystalline metal-organic framework films are deposited onto conductive metal-plate anodes via in situ temperature-controlled electrochemical assembly. The nanostructure of the surface as well as the thickness and uniformity of the film are well controlled. More importantly, the resulting films exhibit enhanced dielectric properties compared to traditional inorganic or organic gate dielectrics. This study demonstrates the successful implementation of the rational design of metal-organic framework thin films on conductive supports with high-performance dielectric properties.

  4. Zeolite-like metal-organic frameworks (ZMOFs) based on the directed assembly of finite metal-organic cubes (MOCs).

    PubMed

    Alkordi, Mohamed H; Brant, Jacilynn A; Wojtas, Lukasz; Kravtsov, Victor Ch; Cairns, Amy J; Eddaoudi, Mohamed

    2009-12-16

    Two zeolite-like metal-organic frameworks (ZMOFs) with lta- and ast- topologies, zeolitic nets that can be interpreted as augmented edge-transitive 8-connected nets, are targeted through directed self-assembly of metal-organic cubes (MOCs) as supermolecular building blocks (SBBs).

  5. Single crystalline hollow metal-organic frameworks: a metal-organic polyhedron single crystal as a sacrificial template.

    PubMed

    Kim, Hyehyun; Oh, Minhak; Kim, Dongwook; Park, Jeongin; Seong, Junmo; Kwak, Sang Kyu; Lah, Myoung Soo

    2015-02-28

    Single crystalline hollow metal-organic frameworks (MOFs) with cavity dimensions on the order of several micrometers and hundreds of micrometers were prepared using a metal-organic polyhedron single crystal as a sacrificial hard template. The hollow nature of the MOF crystal was confirmed by scanning electron microscopy of the crystal sliced using a focused ion beam.

  6. Metal-enhanced chemiluminescence from chromium, copper, nickel, and zinc nanodeposits: Evidence for a second enhancement mechanism in metal-enhanced fluorescence

    SciTech Connect

    Weisenberg, Micah; Zhang Yongxia; Geddes, Chris D.

    2010-09-27

    Over the past decade metal-fluorophore interactions, metal-enhanced fluorescence, have attracted significant research attention, with the technology now becoming common place in life science applications. In this paper, we address the underlying mechanisms of metal-enhanced fluorescence (MEF) and experimentally show using chemiluminescence solutions that MEF is indeed underpinned by two complimentary mechanisms, consistent with the recent reports by Geddes and co-workers [Zhang et al., J. Phys. Chem. C 113, 12095 (2009)] and their enhanced fluorescence hypothesis.

  7. Metal-enhanced chemiluminescence from chromium, copper, nickel, and zinc nanodeposits: Evidence for a second enhancement mechanism in metal-enhanced fluorescence

    NASA Astrophysics Data System (ADS)

    Weisenberg, Micah; Zhang, Yongxia; Geddes, Chris D.

    2010-09-01

    Over the past decade metal-fluorophore interactions, metal-enhanced fluorescence, have attracted significant research attention, with the technology now becoming common place in life science applications. In this paper, we address the underlying mechanisms of metal-enhanced fluorescence (MEF) and experimentally show using chemiluminescence solutions that MEF is indeed underpinned by two complimentary mechanisms, consistent with the recent reports by Geddes and co-workers [Zhang et al., J. Phys. Chem. C 113, 12095 (2009)] and their enhanced fluorescence hypothesis.

  8. Photodeposition of Silver Can Result in Metal-Enhanced Fluorescence

    PubMed Central

    GEDDES, CHRIS D.; PARFENOV, ALEXANDR

    2009-01-01

    Chemically deposited silver particles are widely used for surface-enhanced Raman scattering (SERS) and more recently for surface-enhanced fluorescence (SEF), also known as metal-enhanced fluorescence (MEF). We now show that metallic silver deposited by laser illumination results in an ~7-fold increased intensity of locally bound indocyanine green. The increased intensity is accompanied by a decreased lifetime and increased photostability. These results demonstrate the possibility of photolithographic preparation of surfaces for enhanced fluorescence in microfluidics, medical diagnostics, and other applications. PMID:14658678

  9. Graphene-ribbon-coupled tunable enhanced transmission through metallic grating

    NASA Astrophysics Data System (ADS)

    Peng, Yu-Xiang; He, Meng-Dong; Li, Ze-Jun; Wang, Kai-Jun; Li, Shui; Li, Jian-Bo; Liu, Jian-Qiang; Long, Mengqiu; Hu, Wei-Da; Chen, Xiaoshuang

    2017-01-01

    We report the tunable enhanced transmission of light through a hybrid metal-graphene structure, in which a graphene ribbon array is situated over a metallic grating. The graphene ribbon is employed to make the graphene-insulator-metal waveguide of finite length as a Fabry-Perot (F-P) cavity. When the slit of metallic grating is opened at the position with a maximal magnetic field in F-P resonant cavity, the transmission of light through metallic grating is greatly enhanced since the strongly localized magnetic field is effectively coupled to the slit. The transmission spectrum and the enhancement factor can be adjusted by changing geometrical parameters including the width and the length of slit, the width of graphene ribbon and the period of metallic grating. The transmission peaks exhibit a broad tuning range with a small change in the Fermi energy level of graphene. Moreover, the enhancement factor of transmission peak can be manipulated by the Fermi energy level and the carrier mobility of graphene, and an enhancement factor of 154 is obtained. The findings expand our understanding of hybrid metal-graphene plasmons and have potential applications in building active plasmonic devices.

  10. Multi-Photon Absorption in Metal-Organic Frameworks.

    PubMed

    Medishetty, Raghavender; Nemec, Lydia; Nalla, Venkatram; Henke, Sebastian; Samoc, Marek; Reuter, Karsten; Fischer, Roland A

    2017-09-12

    Multi-photon absorption (MPA) is among the most prominent nonlinear optical (NLO) effects and has applications, for example in telecommunications, defense, photonics and bio-medicines. Established MPA materials include dyes, quantum dots, organometallics and conjugated polymers, most often dispersed in solution. We demonstrate how metal-organic frameworks (MOFs), a novel NLO solid-state materials class, can be designed for exceptionally strong MPA behavior. MOFs consisting of zirconium- and hafnium-oxo-clusters and featuring a chromophore linker based on the tetraphenylethene (TPE) molecule exhibit record high two-photon absorption (2PA) cross section values, up to 3600 GM. The unique modular building-block principle of MOFs allows enhancing and optimizing their MPA properties in a theory guided approach by combining tailored charge polarization, conformational strain, three-dimensional arrangement and alignment of the chromophore linkers in the crystal. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Dissolved organic matter enhances microbial mercury methylation under sulfidic conditions

    USGS Publications Warehouse

    Graham, Andrew M.; Aiken, George R.; Gilmour, Cynthia

    2012-01-01

    Dissolved organic matter (DOM) is generally thought to lower metal bioavailability in aquatic systems due to the formation of metal–DOM complexes that reduce free metal ion concentrations. However, this model may not be pertinent for metal nanoparticles, which are now understood to be ubiquitous, sometimes dominant, metal species in the environment. The influence of DOM on Hg bioavailability to microorganisms was examined under conditions (0.5–5.0 nM Hg and 2–10 μM sulfide) that favor the formation of β-HgS(s) (metacinnabar) nanoparticles. We used the methylation of stable-isotope enriched 201HgCl2 by Desulfovibrio desulfuricans ND132 in short-term washed cell assays as a sensitive, environmentally significant proxy for Hg uptake. Suwannee River humic acid (SRHA) and Williams Lake hydrophobic acid (WLHPoA) substantially enhanced (2- to 38-fold) the bioavailability of Hg to ND132 over a wide range of Hg/DOM ratios (9.4 pmol/mg DOM to 9.4 nmol/mg DOM), including environmentally relevant ratios. Methylmercury (MeHg) production by ND132 increased linearly with either SRHA or WLHPoA concentration, but SRHA, a terrestrially derived DOM, was far more effective at enhancing Hg-methylation than WLHPoA, an aquatic DOM dominated by autochthonous sources. No DOM-dependent enhancement in Hg methylation was observed in Hg–DOM–sulfide solutions amended with sufficient l-cysteine to prevent β-HgS(s) formation. We hypothesize that small HgS particles, stabilized against aggregation by DOM, are bioavailable to Hg-methylating bacteria. Our laboratory experiments provide a mechanism for the positive correlations between DOC and MeHg production observed in many aquatic sediments and wetland soils.

  12. Natural Organic Matter-Promoted Metal Inhibition of Hematite Bioreduction

    NASA Astrophysics Data System (ADS)

    Stone, J. J.; Burgos, W. D.

    2003-12-01

    A developing technology for the in situ treatment of metal and radionuclide contaminants is the stimulation of dissimilatory metal-reducing bacteria (DMRB) to reduce solid phase iron oxides which promote Fe(II) induced chemical reduction of contaminants. Natural organic matter (NOM) can stimulate the biological reduction of solid-phase iron oxides by serving as an electron shuttle and by complexing biogenic Fe(II). The addition of NOM to contaminated zones has been proposed to further stimulate iron reduction and the fortuitous reduction and immobilization of contaminants. However, little research has been conducted on quarternary systems that contain DMRB, ferric oxides, NOM, and metals or radionuclides. The effect of zinc on the biological reduction of hematite and nitrate by the DMRB Shewanella putrefaciens strain CN32 was studied in the absence and presence of NOM. Nitrate was used to compare results between solid-phase and soluble electron acceptors. Previous work has demonstrated that, in the absence of zinc, NOM significantly enhanced hematite bioreduction but slightly inhibited nitrate reduction. In the absence of NOM, zinc was shown to significantly inhibit both hematite and nitrate bioreduction. In the presence of NOM, zinc inhibition of nitrate bioreduction was completely eliminated, presumably due to the NOMs' ability to complex Zn(II) and decrease Zn2+ activity. It was assumed that the presence of NOM would also decrease zinc inhibition of hematite reduction. Contrary to this hypothesis, NOM significantly increased the inhibitory effect of zinc during hematite bioreduction. In addition, non-toxic Mn(II) became inhibitory in the presence of NOM during hematite bioreduction. These results suggest that ternary Me(II)-NOM-oxide surface complexes may specifically inhibit solid-phase bioreduction. Thus, interactions between NOM and metal/radionuclide contaminants may effect the overall efficacy of the biostimulation remediation strategy.

  13. Porous metal-organic frameworks for heterogeneous biomimetic catalysis.

    PubMed

    Zhao, Min; Ou, Sha; Wu, Chuan-De

    2014-04-15

    Metalloporphyrins are the active sites in monooxygenases that oxidize a variety of substrates efficiently and under mild conditions. Researchers have developed artificial metalloporphyrins, but these structures have had limited catalytic applications. Homogeneous artificial metalloporphyrins can undergo catalytic deactivation via suicidal self-oxidation, which lowers their catalytic activity and sustainability relative to their counterparts in Nature. Heme molecules in protein scaffolds can maintain high efficiency over numerous catalytic cycles. Therefore, we wondered if immobilizing metalloporphyrin moieties within porous metal-organic frameworks (MOFs) could stabilize these structures and facilitate the molecular recognition of substrates and produce highly efficient biomimetic catalysis. In this Account, we describe our research to develop multifunctional porphyrinic frameworks as highly efficient heterogeneous biomimetic catalysts. Our studies indicate that porous porphyrinic frameworks provide an excellent platform for mimicking the activity of biocatalysts and developing new heterogeneous catalysts that effect new chemical transformations under mild conditions. The porous structures and framework topologies of the porphyrinic frameworks depend on the configurations, coordination donors, and porphyrin metal ions of the metalloporphyrin moieties. To improve the activity of porous porphyrinic frameworks, we have developed a two-step synthesis that introduces the functional polyoxometalates (POMs) into POM-porphyrin hybrid materials. To tune the pore structures and the catalytic properties of porphyrinic frameworks, we have designed metalloporphyrin M-H8OCPP ligands with four m-benzenedicarboxylate moieties, and introduced the secondary auxiliary ligands. The porphyrin metal ions and the secondary functional moieties that are incorporated into porous metal-organic frameworks greatly influence the catalytic properties and activities of porphyrinic frameworks in

  14. Electroluminescence Efficiency Enhancement using Metal Nanoparticles

    DTIC Science & Technology

    2008-06-22

    the vicinity of isolated metal nanoparticles and their arrays. Using the example of an InGaN /GaN quantum-well active region positioned in close...emitters placed in the vicinity of isolated metal nanoparticles and their arrays. Using the example of an InGaN /GaN quantum-well active region...electron-hole pair states are localized on the scale of the coherent length on the order of a few nanometers at room temperature, the spontaneous

  15. Plasmonic-enhanced organic photovoltaics: breaking the 10% efficiency barrier.

    PubMed

    Gan, Qiaoqiang; Bartoli, Filbert J; Kafafi, Zakya H

    2013-05-07

    Recent advances in molecular organic photovoltaics (OPVs) have shown 10% power conversion efficiency (PCE) for single-junction cells, which put them in direct competition with PVs based on amorphous silicon. Incorporation of plasmonic nanostructures for light trapping in these thin-film devices offers an attractive solution to realize higher-efficiency OPVs with PCE>10%. This article reviews recent progress on plasmonic-enhanced OPV devices using metallic nanoparticles, and one-dimensional (1D) and two-dimensional (2D) patterned periodic nanostructures. We discuss the benefits of using various plasmonic nanostructures for broad-band, polarization-insensitive and angle-independent absorption enhancement, and their integration with one or two electrode(s) of an OPV device.

  16. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes.

    PubMed

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X; Urban, Ania; Thacker, Nathan C; Lin, Wenbin

    2016-08-30

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  17. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes

    NASA Astrophysics Data System (ADS)

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin

    2016-08-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  18. On nutrients and trace metals: Effects from Enhanced Weathering

    NASA Astrophysics Data System (ADS)

    Amann, T.; Hartmann, J.

    2015-12-01

    The application of rock flour on suitable land ("Enhanced Weathering") is one proposed strategy to reduce the increase of atmospheric CO2 concentrations. At the same time it is an old and established method to add fertiliser and influence soil properties. Investigations of this method focused on the impact on the carbonate system, as well as on engineering aspects of a large-scale application, but potential side effects were never discussed quantitatively. We analysed about 120,000 geochemically characterised volcanic rock samples from the literature. Applying basic statistics, theoretical release rates of nutrients and potential contaminants by Enhanced Weathering were evaluated for typical rock types. Applied rock material can contain significant amounts of essential or beneficial nutrients (potassium, phosphorus, micronutrients). Their release can partly cover the demand of major crops like wheat, rice or corn, thereby increasing crop yield on degraded soils. However, the concentrations of considered elements are variable within a specific rock type, depending on the geological setting. High heavy metal concentrations are found in (ultra-) basic rocks, the class with the highest CO2 drawdown potential. More acidic rocks contain less or no critical amounts, but sequester less CO2. Findings show that the rock selection determines the capability to supply significant amounts of nutrients, which could partly substitute industrial mineral fertiliser usage. At the same time, the release of harmful trace element has to be considered. Through careful selection of regionally available rocks, benefits could be maximised and drawbacks reduced. The deployment of Enhanced Weathering to sequester CO2 and to ameliorate soils necessitates an ecosystem management, considering the release and fate of weathered elements in plants, soils and water. Cropland with degraded soils would benefit while having a net negative CO2 effect, while other carbon dioxide removal strategies, like

  19. Nanocomposites for enhancing current collection in organic solar cells

    NASA Astrophysics Data System (ADS)

    Peterson, Eric David

    The enhancement of charge collection in organic photovoltaics by using nanocomposite materials is investigated. Two such approaches are detailed in this thesis. Chapter 1 addresses the addition of metal nanorods to the PEDOT layer of an organic solar cell in an attempt to focus incident light for better absorption by the polymer layer. Composites designed to facilitate charge transfer from nanoparticles to the polymer/fullerene system are the focus of the second chapter. Chapter 3 details a refinement to the research presented in chapter 2, adding fullerenes to the mix and creating ternary systems and providing an analytical framework for evaluating these systems. The material choices are expanded in chapter 4; we investigate a new, lower band gap conjugated polymer (PCPDTBT) as well as core-shell nanoparticles and how they interact in the system. Results are reported and further avenues of research are suggested.

  20. Biomimetic mineralization of metal-organic frameworks as protective coatings for biomacromolecules

    PubMed Central

    Liang, Kang; Ricco, Raffaele; Doherty, Cara M.; Styles, Mark J.; Bell, Stephen; Kirby, Nigel; Mudie, Stephen; Haylock, David; Hill, Anita J.; Doonan, Christian J.; Falcaro, Paolo

    2015-01-01

    Enhancing the robustness of functional biomacromolecules is a critical challenge in biotechnology, which if addressed would enhance their use in pharmaceuticals, chemical processing and biostorage. Here we report a novel method, inspired by natural biomineralization processes, which provides unprecedented protection of biomacromolecules by encapsulating them within a class of porous materials termed metal-organic frameworks. We show that proteins, enzymes and DNA rapidly induce the formation of protective metal-organic framework coatings under physiological conditions by concentrating the framework building blocks and facilitating crystallization around the biomacromolecules. The resulting biocomposite is stable under conditions that would normally decompose many biological macromolecules. For example, urease and horseradish peroxidase protected within a metal-organic framework shell are found to retain bioactivity after being treated at 80 °C and boiled in dimethylformamide (153 °C), respectively. This rapid, low-cost biomimetic mineralization process gives rise to new possibilities for the exploitation of biomacromolecules. PMID:26041070

  1. Biomimetic mineralization of metal-organic frameworks as protective coatings for biomacromolecules

    NASA Astrophysics Data System (ADS)

    Liang, Kang; Ricco, Raffaele; Doherty, Cara M.; Styles, Mark J.; Bell, Stephen; Kirby, Nigel; Mudie, Stephen; Haylock, David; Hill, Anita J.; Doonan, Christian J.; Falcaro, Paolo

    2015-06-01

    Enhancing the robustness of functional biomacromolecules is a critical challenge in biotechnology, which if addressed would enhance their use in pharmaceuticals, chemical processing and biostorage. Here we report a novel method, inspired by natural biomineralization processes, which provides unprecedented protection of biomacromolecules by encapsulating them within a class of porous materials termed metal-organic frameworks. We show that proteins, enzymes and DNA rapidly induce the formation of protective metal-organic framework coatings under physiological conditions by concentrating the framework building blocks and facilitating crystallization around the biomacromolecules. The resulting biocomposite is stable under conditions that would normally decompose many biological macromolecules. For example, urease and horseradish peroxidase protected within a metal-organic framework shell are found to retain bioactivity after being treated at 80 °C and boiled in dimethylformamide (153 °C), respectively. This rapid, low-cost biomimetic mineralization process gives rise to new possibilities for the exploitation of biomacromolecules.

  2. Photochemical deterioration of the organic/metal contacts in organic optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Williams, Graeme; Tsui, Ting; Aziz, Hany

    2012-09-01

    We study the effect of exposure to light on a wide range of organic/metal contacts that are commonly used in organic optoelectronic devices and found that irradiation by light in the visible and UV range results in a gradual deterioration in their electrical properties. This photo-induced contact degradation reduces both charge injection (i.e., from the metal to the organic layer) and charge extraction (i.e., from the organic layer to the metal). X-ray photoelectron spectroscopy (XPS) measurements reveal detectable changes in the interface characteristics after irradiation, indicating that the photo-degradation is chemical in nature. Changes in XPS characteristics after irradiation suggests a possible reduction in bonds associated with organic-metal complexes. Measurements of interfacial adhesion strength using the four-point flexure technique reveal a decrease in organic/metal adhesion in irradiated samples, consistent with a decrease in metal-organic bond density. The results shed the light on a new material degradation mechanism that appears to have a wide presence in organic/metal interfaces in general, and which likely plays a key role in limiting the stability of various organic optoelectronic devices such as organic light emitting devices, organic solar cells, and organic photo-detectors.

  3. Surface Plasmon Enhanced Phosphorescent Organic Light Emitting Diodes

    SciTech Connect

    Guillermo Bazan; Alexander Mikhailovsky

    2008-08-01

    The objective of the proposed work was to develop the fundamental understanding and practical techniques for enhancement of Phosphorescent Organic Light Emitting Diodes (PhOLEDs) performance by utilizing radiative decay control technology. Briefly, the main technical goal is the acceleration of radiative recombination rate in organometallic triplet emitters by using the interaction with surface plasmon resonances in noble metal nanostructures. Increased photonic output will enable one to eliminate constraints imposed on PhOLED efficiency by triplet-triplet annihilation, triplet-polaron annihilation, and saturation of chromophores with long radiative decay times. Surface plasmon enhanced (SPE) PhOLEDs will operate more efficiently at high injection current densities and will be less prone to degradation mechanisms. Additionally, introduction of metal nanostructures into PhOLEDs may improve their performance due to the improvement of the charge transport through organic layers via multiple possible mechanisms ('electrical bridging' effects, doping-like phenomena, etc.). SPE PhOLED technology is particularly beneficial for solution-fabricated electrophosphorescent devices. Small transition moment of triplet emitters allows achieving a significant enhancement of the emission rate while keeping undesirable quenching processes introduced by the metal nanostructures at a reasonably low level. Plasmonic structures can be introduced easily into solution-fabricated PhOLEDs by blending and spin coating techniques and can be used for enhancement of performance in existing device architectures. This constitutes a significant benefit for a large scale fabrication of PhOLEDs, e.g. by roll-to-roll fabrication techniques. Besides multieexciton annihilation, the power efficacy of PhOLEDs is often limited by high operational bias voltages required for overcoming built-in potential barriers to injection and transport of electrical charges through a device. This problem is especially

  4. Quantification of Stereochemical Communication in Metal-Organic Assemblies.

    PubMed

    Castilla, Ana M; Miller, Mark A; Nitschke, Jonathan R; Smulders, Maarten M J

    2016-08-26

    The derivation and application of a statistical mechanical model to quantify stereochemical communication in metal-organic assemblies is reported. The factors affecting the stereochemical communication within and between the metal stereocenters of the assemblies were experimentally studied by optical spectroscopy and analyzed in terms of a free energy penalty per "incorrect" amine enantiomer incorporated, and a free energy of coupling between stereocenters. These intra- and inter-vertex coupling constants are used to track the degree of stereochemical communication across a range of metal-organic assemblies (employing different ligands, peripheral amines, and metals); temperature-dependent equilibria between diastereomeric cages are also quantified. The model thus provides a unified understanding of the factors that shape the chirotopic void spaces enclosed by metal-organic container molecules.

  5. Organic matter in hydrothermal metal ores and hydrothermal fluids

    USGS Publications Warehouse

    Orem, W.H.; Spiker, E. C.; Kotra, R.K.

    1990-01-01

    Massive polymetallic sulfides are currently being deposited around active submarine hydrothermal vents associated with spreading centers. Chemoautolithotrophic bacteria are responsible for the high production of organic matter also associated with modern submarine hydrothermal activity. Thus, there is a significant potential for organic matter/metal interactions in these systems. We have studied modern and ancient hydrothermal metal ores and modern hydrothermal fluids in order to establish the amounts and origin of the organic matter associated with the metal ores. Twenty-six samples from modern and ancient hydrothermal systems were surveyed for their total organic C contents. Organic C values ranged from 0.01% to nearly 4.0% in these samples. Metal ores from modern and ancient sediment-covered hydrothermal systems had higher organic C values than those from modern and ancient hydrothermal systems lacking appreciable sedimentary cover. One massive pyrite sample from the Galapagos spreading center (3% organic C) had stable isotope values of -27.4% (??13C) and 2.1% (??15N), similar to those in benthic siphonophors from active vents and distinct from seep sea sedimentary organic matter. This result coupled with other analyses (e.g. 13C NMR, pyrolysis/GC, SEM) of this and other samples suggests that much of the organic matter may originate from chemoautolithotrophic bacteria at the vents. However, the organic matter in hydrothermal metal ores from sediment covered vents probably arises from complex sedimentary organic matter by hydrothermal pyrolysis. The dissolved organic C concentrations of hydrothermal fluids from one site (Juan de Fuca Ridge) were found to be the same as that of background seawater. This result may indicate that dissolved organic C is effectively scavenged from hydrothermal fluids by biological activity or by co-precipitation with metal ores. ?? 1990.

  6. Combinatorial Approach to Studying Metal Enhanced Fluorescence from Quantum Dots

    NASA Astrophysics Data System (ADS)

    Le, Nguyet; Corrigan, Timothy; Norton, Michael; Neff, David

    2013-03-01

    Fluorescence is extensively used in biochemistry for determining the concentration or purity of molecules in a biological environment. In metal-enhanced fluorescence (MEF), the fluorescence molecules separated from a metal surface by several nanometers can be enhanced. The fluorescent enhancement is dependent on the size and spacing of the nanoparticles, as has been shown previously for a number of fluorophore molecules. Fluorescence from quantum dots is of particular interest because the quantum dots do not lose fluorescence ability when exposed to light and they have higher intensity of fluorescence. The purpose of this study is to determine the effect of size and spacing on fluorescence intensity when coupling gold nano-particles with quantum dots. We employ a combinatorial approach, depositing gold particles ranging in diameter from 30 nm to 130 nm with varied spacings onto the substrate, followed by a protein spacer-layer and quantum dots. The fluorescence signal from the metal enhanced quantum dots were determined by confocal microscopy.

  7. Metal solubility enhancing peptides derived from barley protein.

    PubMed

    Eckert, Ewelina; Bamdad, Fatemeh; Chen, Lingyun

    2014-09-15

    Mineral supplements are required to be soluble as their bioavailability is highly correlated to their solubility in body fluids. In this study, metal binding capacity of barley protein hydrolysates and their purified fractions was investigated and expressed as increase in solubility of metal ions. Metal ions in the presence of hydrolysates exhibited a remarkable increase in solubility: 118, 32, 10, 29 and 35-fold for Fe(2+), Fe(3+), Ca(2+), Cu(2+) and Zn(2+), respectively. A mixture of low molecular weight peptides possesses a synergistic combination of both charged and hydrophobic residues and achieves the best binding metal ions. Electrostatic interactions via charged side chains and coordination binding with His and Cys, initially attract the metal ions and, afterward, hydrophobic interactions and aromatic ring stacking stabilize the positioning of metal ions in the structure of the peptide. Barley hordein hydrolysates show potential as dietary supplements that enhance both mineral solubility and bioavailability. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Metal Nanostructures for Detection and Imaging Enhancements

    DTIC Science & Technology

    2011-01-03

    source spectrum, is delivered into a pig adipose sample. OCT is a widely used optical imaging technique for the diagnoses of many diseases [27-29... Fahr , C. Rockstuhl, and F. Lederer, “Engineering the randomness for enhanced absorption in solar cells,” Appl. Phys. Lett. 92, 171114 (2008). 7. T...Rockstuhl, S. Fahr , and F. Lederer, “Absorption enhancement in solar cells by localized plasmon polaritons,” J. Appl. Phys. 104, 123102 (2008). 31. A

  9. USING ZERO-VALENT METAL NANOPARTICLES TO REMEDIATE ORGANIC CONTAMINANTS

    EPA Science Inventory

    The transport of organic contaminants down the soil profile constitutes a serious threat to the quality of ground water. Zero-valent metals are considered innocuous abiotic agents capable of mediating decontamination processes in terrestrial systems. In this investigation, ze...

  10. From metal-organic framework to intrinsically fluorescent carbon nanodots.

    PubMed

    Amali, Arlin Jose; Hoshino, Hideto; Wu, Chun; Ando, Masanori; Xu, Qiang

    2014-07-01

    Highly photoluminescent carbon nanodots (CNDs) were synthesized for the first time from metal-organic framework (MOF, ZIF-8) nanoparticles. Coupled with fluorescence and non-toxic characteristics, these carbon nanodots could potentially be used in biosafe color patterning.

  11. Applications of metal-organic frameworks in heterogeneous supramolecular catalysis.

    PubMed

    Liu, Jiewei; Chen, Lianfen; Cui, Hao; Zhang, Jianyong; Zhang, Li; Su, Cheng-Yong

    2014-08-21

    This review summarizes the use of metal-organic frameworks (MOFs) as a versatile supramolecular platform to develop heterogeneous catalysts for a variety of organic reactions, especially for liquid-phase reactions. Following a background introduction about catalytic relevance to various metal-organic materials, crystal engineering of MOFs, characterization and evaluation methods of MOF catalysis, we categorize catalytic MOFs based on the types of active sites, including coordinatively unsaturated metal sites (CUMs), metalloligands, functional organic sites (FOS), as well as metal nanoparticles (MNPs) embedded in the cavities. Throughout the review, we emphasize the incidental or deliberate formation of active sites, the stability, heterogeneity and shape/size selectivity for MOF catalysis. Finally, we briefly introduce their relevance into photo- and biomimetic catalysis, and compare MOFs with other typical porous solids such as zeolites and mesoporous silica with regard to their different attributes, and provide our view on future trends and developments in MOF-based catalysis.

  12. USING ZERO-VALENT METAL NANOPARTICLES TO REMEDIATE ORGANIC CONTAMINANTS

    EPA Science Inventory

    The transport of organic contaminants down the soil profile constitutes a serious threat to the quality of ground water. Zero-valent metals are considered innocuous abiotic agents capable of mediating decontamination processes in terrestrial systems. In this investigation, ze...

  13. Porous materials: Lining up metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Champness, Neil R.

    2017-02-01

    A new report demonstrates an innovative approach to aligning crystallites of metal-organic frameworks such that thin films are created with oriented channels -- potentially overcoming one of the major barriers to application of these highly topical materials.

  14. Toward "metalloMOFzymes": Metal-Organic Frameworks with Single-Site Metal Catalysts for Small-Molecule Transformations.

    PubMed

    Cohen, Seth M; Zhang, Zhenjie; Boissonnault, Jake A

    2016-08-01

    Metal-organic frameworks (MOFs) are being increasingly studied as scaffolds and supports for catalysis. The solid-state structures of MOFs, combined with their high porosity, suggest that MOFs may possess advantages shared by both heterogeneous and homogeneous catalysts, with few of the shortcomings of either. Herein, efforts to create single-site catalytic metal centers appended to the organic ligand struts of MOFs will be discussed. Reactions important for advanced energy applications, such as H2 production and CO2 reduction, will be highlighted. Examining how these active sites can be introduced, their performance, and their existing limitations should provide direction for design of the next generation of MOF-based catalysts for energy-relevant, small-molecule transformations. Finally, the introduction of second-sphere interactions (e.g., hydrogen bonding via squaramide groups) as a possible route to enhancing the activity of these metal centers is reported.

  15. On the performance of Cu-BTC metal organic framework for carbon tetrachloride gas removal.

    PubMed

    Calero, Sofía; Martín-Calvo, Ana; Hamad, Said; García-Pérez, Elena

    2011-01-07

    The performance of Cu-BTC metal organic framework for carbon tetrachloride removal from air has been studied using molecular simulations. According to our results, this material shows extremely high adsorption selectivity in favour of carbon tetrachloride. We demonstrate that this selectivity can be further enhanced by selective blockage of the framework.

  16. Multi-responsive metal-organic lantern cages in solution.

    PubMed

    Brega, Valentina; Zeller, Matthias; He, Yufan; Lu, H Peter; Klosterman, Jeremy K

    2015-03-25

    Soluble copper-based M4L4 lantern-type metal-organic cages bearing internal amines were synthesized. The solution state integrity of the paramagnetic metal-organic cages was demonstrated using NMR, DLS, MS, and AFM spectroscopy. 1D supramolecular pillars of pre-formed cages or covalent host-guest complexes selectively formed upon treatment with 4,4'-bipyridine and acetic anhydride, respectively.

  17. Toxic Industrial Chemical Removal by Isostructural Metal-Organic Frameworks

    DTIC Science & Technology

    2011-01-01

    distance between the MOF -74 metal and the adsorbed hydrogen molecule. In addition, the authors studied the methane storage capabilities of these MOFs and...industrial processes such as gas storage , separations, and catalysis [1-4]. MOFs self-assemble using combinations of metal clusters and organic linking...and organic linkers to achieve better selectivity and activity towards chemicals such as, hydrogen , carbon dioxide, and methane, for gas storage

  18. Metal-organic framework for the separation of alkane isomers

    DOEpatents

    Long, Jeffrey R.; Herm, Zoey R.; Wiers, Brian M.; Krishna, Rajamani

    2017-01-10

    A metal organic framework Fe.sub.2(bdp).sub.3 (BDP.sup.2-=1,4-benzenedipyrazolate) with triangular channels is particularly suited for C5-C7 separations of alkanes according to the number of branches in the molecule rather than by carbon number. The metal-organic framework can offer pore geometries that is unavailable in zeolites or other porous media, facilitating distinct types of shape-based molecular separations.

  19. Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

    DOEpatents

    Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.; Lloyd, Matthew T.; Widjonarko, Nicodemus Edwin; Miedaner, Alexander; Curtis, Calvin J.; Ginley, David S.; Olson, Dana C.

    2017-01-10

    A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

  20. [Effects of Tillage on Distribution of Heavy Metals and Organic Matter Within Purple Paddy Soil Aggregates].

    PubMed

    Shi, Qiong-bin; Zhao, Xiu-lan; Chang, Tong-ju; Lu, Ji-wen

    2016-05-15

    A long-term experiment was utilized to study the effects of tillage methods on the contents and distribution characteristics of organic matter and heavy metals (Cu, Zn, Pb, Cd, Fe and Mn) in aggregates with different sizes (including 1-2, 0.25-1, 0.05-0.25 mm and < 0.05 mm) in a purple paddy soil under two tillage methods including flooded paddy field (FPF) and paddy-upland rotation (PR). The relationship between heavy metals and organic matter in soil aggregates was also analyzed. The results showed that the aggregates of two tillage methods were dominated by 0.05-0.25 mm and < 0.05 mm particle size, respectively. The contents of organic matter in each aggregate decreased with the decrease of aggregate sizes, however, compared to PR, FPF could significantly increase the contents of organic matter in soils and aggregates. The tillage methods did not significantly affect the contents of heavy metals in soils, but FPF could enhance the accumulation and distribution of aggregate, organic matter and heavy metals in aggregates with diameters of 1-2 mm and 0.25-1 mm. Correlation analysis found that there was a negative correlation between the contents of heavy metals and organic matter in soil aggregates, but a positive correlation between the amounts of heavy metal and organic matter accumulated in soil aggregates. From the slope of the correlation analysis equations, we could found that the sensitivities of heavy metals to the changes of soil organic matters followed the order of Mn > Zn > Pb > Cu > Fe > Cd under the same tillage. When it came to the same heavy metal, it was more sensitive in PR than in FPF.

  1. Metal Enhanced Fluorescence on Silicon Wafer Substrates

    PubMed Central

    Gryczynski, I.; Matveeva, E.G.; Sarkar, P.; Bharill, S.; Borejdo, J.; Mandecki, W.; Akopova, I.; Gryczynski, Z.

    2008-01-01

    We report on the fluorescence enhancement induced by silver island film (SIF) deposited on a silicon wafer. The model immunoassay was studied on silvered and unsilvered wafers. The fluorescence brightness of Rhodamine Red X increased about 300% on the SIF, while the lifetime was reduced by several fold and the photostability increased substantially. We discuss potential uses of silicon wafer substrates in multiplex assays in which the fluorescence is enhanced due to the SIF, and the multiplexing is achieved by using micro transponders. PMID:19137060

  2. Photoluminescence emission from Alq3 organic layer in metal-Alq3-metal plasmonic structure

    NASA Astrophysics Data System (ADS)

    Huang, Bohr-Ran; Liao, Chung-Chi; Fan, Wan-Ting; Wu, Jin-Han; Chen, Cheng-Chang; Lin, Yi-Ping; Li, Jung-Yu; Chen, Shih-Pu; Ke, Wen-Cheng; Chen, Nai-Chuan

    2014-06-01

    The emission properties of an organic layer embedded in a metal-organic-metal (MOM) structure were investigated. A partially radiative odd-SPW as well as a non-radiative even-SPW modes are supported by hybridization of the SPW modes on the opposite organic/metal interface in the structure. Because of the competition by this radiative SPW, the population of excitons that recombine to form non-radiative SPW should be reduced. This may account for why the photoluminescence intensity of the MOM sample is higher than that of an organic-metal sample even though the MOM sample has an additional metal layer that should intuitively act as a filter.

  3. Microwave enhanced oxidation treatment of organic fertilizers.

    PubMed

    More, Abhilasha; Srinivasan, Asha; Liao, Ping Huang; Lo, Kwang Victor

    2017-08-01

    Liquid organic fertilizers (LOFs) are relatively easier to degrade than those of solid organic fertilizers, and the nutrients are readily available for plant uptake. Microwave enhanced advanced oxidation treatment (MW/H2 O2 -AOP) was used to convert solid organic fertilizers (insoluble blood meal, bone meal, feather meal, sunflower ash and a mixture) into LOF. After the MW/H2 O2 -AOP treatment, high soluble nitrogen (11-29%), soluble phosphorus (64%) and potassium (92%), as well as low total suspended solids content could be obtained. The resulting LOF would make the nutrients more bioavailable, and would provide some of them for the plant uptake immediately. Temperature and hydrogen peroxide dosage were found to be significant factors affecting nitrogen release from blood meal and feather meal, while temperature and pH were found to be significant factors for solubilizing phosphorus and potassium from bone meal and ash, respectively. The MW/H2 O2 -AOP reduced suspended solids, and released nutrients into solution; therefore, it was an effective treatment method to make LOFs. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  4. Metals as radio-enhancers in oncology: The industry perspective

    SciTech Connect

    Pottier, Agnés Borghi, Elsa; Levy, Laurent

    2015-12-18

    Radio-enhancers, metal-based nanosized agents, could play a key role in oncology. They may unlock the potential of radiotherapy by enhancing the radiation dose deposit within tumors when the ionizing radiation source is ‘on’, while exhibiting chemically inert behavior in cellular and subcellular systems when the radiation beam is ‘off’. Important decision points support the development of these new type of therapeutic agents originated from nanotechnology. Here, we discuss from an industry perspective, the interest of developing radio-enhancer agents to improve tumor control, the relevance of nanotechnology to achieve adequate therapeutic attributes, and present some considerations for their development in oncology. - Highlights: • Oncology is a field of high unmet medical need. • Despites of its widespread usage, radiation therapy presents a narrow therapeutic window. • High density material at the nanoscale may enhance radiation dose deposit from cancer cells. • Metal-based nanosized radio-enhancers could unlock the potential of radiotherapy.

  5. Multi-shelled Hollow Metal-Organic Frameworks.

    PubMed

    Liu, Wenxian; Huang, Jijiang; Yang, Qiu; Wang, Shiji; Sun, Xiaoming; Zhang, Weina; Liu, Junfeng; Huo, Fengwei

    2017-05-08

    Hollow metal-organic frameworks (MOFs) are promising materials with sophisticated structures, such as multiple shells, that cannot only enhance the properties of MOFs but also endow them with new functions. Herein, we show a rational strategy to fabricate multi-shelled hollow chromium (III) terephthalate MOFs (MIL-101) with single-crystalline shells through step-by-step crystal growth and subsequent etching processes. This strategy relies on the creation of inhomogeneous MOF crystals in which the outer layer is chemically more robust than the inner layer and can be selectively etched by acetic acid. The regulation of MOF nucleation and crystallization allows the tailoring of the cavity size and shell thickness of each layer. The resultant multi-shelled hollow MIL-101 crystals show significantly enhanced catalytic activity during styrene oxidation. The insight gained from this systematic study will aid in the rational design and synthesis of other multi-shelled hollow structures and the further expansion of their applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Plasmonic effects for light concentration in organic photovoltaic thin films induced by hexagonal periodic metallic nanospheres

    NASA Astrophysics Data System (ADS)

    Zhu, Jinfeng; Xue, Mei; Shen, Huajun; Wu, Zhe; Kim, Seongku; Ho, Jyh-Jier; Hassani-Afshar, Aram; Zeng, Baoqing; Wang, Kang L.

    2011-04-01

    We present a plasmonic nanostructure design by embedding a layer of hexagonal periodic metallic nanospheres between the active layer and transparent anode for bulk heterojunction organic solar cells. The hybrid structure shows broadband optical absorption enhancement from localized surface plasmon resonance with a weak dependence on polarization of incident light. We also theoretically study the optimization of the design to enhance the absorption up to 1.90 times for a typical hybrid active layer based on a low band gap material.

  7. Water-enhanced solvation of organics

    SciTech Connect

    Lee, Jane H.

    1993-07-01

    Water-enhanced solvation (WES) was explored for Lewis acid solutes in Lewis base organic solvents, to develop cheap extract regeneration processes. WES for solid solutes was determined from ratios of solubilities of solutes in water-sat. and low-water solvent; both were determined from solid-liquid equilibrium. Vapor-headspace analysis was used to determine solute activity coefficients as function of organic phase water concentration. WES magnitudes of volatile solutes were normalized, set equal to slope of log γs vs xw/xs curve. From graph shape Δ(log γs) represents relative change in solute activity coefficient. Solutes investigated by vapor-headspace analysis were acetic acid, propionic acid, ethanol, 1,2-propylene glycol, 2,3-butylene glycol. Monocarboxylic acids had largest decrease in activity coefficient with water addition followed by glycols and alcohols. Propionic acid in cyclohexanone showed greatest water-enhancement Δ(log γacid)/Δ(xw/xacid) = -0.25. In methylcyclohexanone, the decrease of the activity coefficient of propionic acid was -0.19. Activity coefficient of propionic acid in methylcyclohexanone stopped decreasing once the water reached a 2:1 water to acid mole ratio, implying a stoichiometric relation between water, ketone, and acid. Except for 2,3-butanediol, activity coefficients of the solutes studied decreased monotonically with water content. Activity coefficient curves of ethanol, 1,2-propanediol and 2,3-butanediol did not level off at large water/solute mole ratio. Solutes investigated by solid-liquid equilibrium were citric acid, gallic acid, phenol, xylenols, 2-naphthol. Saturation concentration of citric acid in anhydrous butyl acetate increased from 0.0009 to 0.087 mol/L after 1.3 % (g/g) water co-dissolved into organic phase. Effect of water-enhanced solvation for citric acid is very large but very small for phenol and its derivatives.

  8. Reconfigurable electronics using conducting metal-organic frameworks

    DOEpatents

    Allendorf, Mark D.; Talin, Albert Alec; Leonard, Francois; Stavila, Vitalie

    2017-07-18

    A device including a porous metal organic framework (MOF) disposed between two terminals, the device including a first state wherein the MOF is infiltrated by a guest species to form an electrical path between the terminals and a second state wherein the electrical conductivity of the MOF is less than the electrical conductivity in the first state. A method including switching a porous metal organic framework (MOF) between two terminals from a first state wherein a metal site in the MOF is infiltrated by a guest species that is capable of charge transfer to a second state wherein the MOF is less electrically conductive than in the first state.

  9. A metal-organic framework-derived bifunctional oxygen electrocatalyst

    NASA Astrophysics Data System (ADS)

    Xia, Bao Yu; Yan, Ya; Li, Nan; Wu, Hao Bin; Lou, Xiong Wen (David); Wang, Xin

    2016-01-01

    Oxygen electrocatalysis is of great importance for many energy storage and conversion technologies, including fuel cells, metal-air batteries and water electrolysis. Replacing noble metal-based electrocatalysts with highly efficient and inexpensive non-noble metal-based oxygen electrocatalysts is critical for the practical applications of these technologies. Here we report a general approach for the synthesis of hollow frameworks of nitrogen-doped carbon nanotubes derived from metal-organic frameworks, which exhibit higher electrocatalytic activity and stability for oxygen reduction and evolution than commercial Pt/C electrocatalysts. The remarkable electrochemical properties are mainly attributed to the synergistic effect from chemical compositions and the robust hollow structure composed of interconnected crystalline nitrogen-doped carbon nanotubes. The presented strategy for controlled design and synthesis of metal-organic framework-derived functional nanomaterials offers prospects in developing highly active electrocatalysts in electrochemical energy devices.

  10. Ligand design for functional metal-organic frameworks.

    PubMed

    Paz, Filipe A Almeida; Klinowski, Jacek; Vilela, Sérgio M F; Tomé, João P C; Cavaleiro, José A S; Rocha, João

    2012-02-07

    Metal-organic frameworks (MOFs), also known as coordination polymers, are formed by the self-assembly of metallic centres and bridging organic linkers. In this critical review, we review the key advances in the field and discuss the relationship between the nature and structure of specifically designed organic linkers and the properties of the products. Practical examples demonstrate that the physical and chemical properties of the linkers play a decisive role in the properties of novel functional MOFs. We focus on target materials suitable for the storage of hydrogen and methane, sequestration of carbon dioxide, gas separation, heterogeneous catalysis and as magnetic and photoluminescent materials capable of both metal- and ligand-centred emission, ion exchangers and molecular sieves. The advantages of highly active discrete complexes as metal-bearing ligands in the construction of MOFs are also briefly reviewed (128 references). This journal is © The Royal Society of Chemistry 2012

  11. Enhancement of Raman scattering from molecules placed near metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Barbiellini, B.

    2017-01-01

    Large Raman scattering cross sections from molecules on surfaces of metallic nanoparticles are described within a renormalization-group theory. In this approach the valence electrons of the molecules are embedded in an effective medium described by a dielectric function, which integrates out the effect of the plasmonic excitations of the metallic nanoparticles. The source of the enhanced photon inelastic scattering is produced by the resonant excitation of surface plasmons at the metallic nanoparticles. A similar theory has been successfully used to explain the resonant x-ray inelastic scattering and the behavior of nonlinear susceptibilities at the x-ray edges.

  12. Separating of organic and inorganic forms of metals in sediments

    SciTech Connect

    Hsieh, Yuch Ping

    1995-12-31

    Separating organic forms of trace metals from their pyritic forms is a difficult problem one constantly faced when studying trace metals in a reduced soil. It is known that pyritic forms and organic forms of metals can be separated by solubilizing pyritic forms in a reducing agent while leaving the organic forms intact. The problem is that the reducing agents used in those procedures are also metals such as Cr or Sn that makes the study of trace metals impossible. If oxidation procedure is used, both pyritic anorganic forms oxidize almost at the same rate which resulted in hardly any separation. Reported here is a new procedure that oxidizes > 95% of pyritic forms and < 5% of organic forms of heavy metal using a modified hydrogen peroxide solution. The procedure is examined using mixtures of standards and salt marsh sediments. Using this procedure, we prove that rarely any added Cu retained in salt marshes is in organic form, a result has been repeatedly mistakenly reported.

  13. Role of alkali metal promoter in enhancing lateral growth of monolayer transition metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Kim, Hyun; Han, Gang Hee; Yun, Seok Joon; Zhao, Jiong; Keum, Dong Hoon; Jeong, Hye Yun; Hue Ly, Thuc; Jin, Youngjo; Park, Ji-Hoon; Moon, Byoung Hee; Kim, Sung-Wng; Lee, Young Hee

    2017-09-01

    Synthesis of monolayer transition metal dichalcogenides (TMDs) via chemical vapor deposition relies on several factors such as precursor, promoter, substrate, and surface treatment of substrate. Among them, the use of promoter is crucial for obtaining uniform and large-area monolayer TMDs. Although promoters have been speculated to enhance adhesion of precursors to the substrate, their precise role in the growth mechanism has rarely been discussed. Here, we report the role of alkali metal promoter in growing monolayer TMDs. The growth occurred via the formation of sodium metal oxides which prevent the evaporation of metal precursor. Furthermore, the silicon oxide substrate helped to decrease the Gibbs free energy by forming sodium silicon oxide compounds. The resulting sodium metal oxide was anchored within such concavities created by corrosion of silicon oxide. Consequently, the wettability of the precursors to silicon oxide was improved, leading to enhance lateral growth of monolayer TMDs.

  14. Role of alkali metal promoter in enhancing lateral growth of monolayer transition metal dichalcogenides.

    PubMed

    Kim, Hyun; Han, Gang Hee; Yun, Seok Joon; Zhao, Jiong; Keum, Dong Hoon; Jeong, Hye Yun; Ly, Thuc Hue; Jin, Youngjo; Park, Ji-Hoon; Moon, Byoung Hee; Kim, Sung-Wng; Lee, Young Hee

    2017-09-08

    Synthesis of monolayer transition metal dichalcogenides (TMDs) via chemical vapor deposition relies on several factors such as precursor, promoter, substrate, and surface treatment of substrate. Among them, the use of promoter is crucial for obtaining uniform and large-area monolayer TMDs. Although promoters have been speculated to enhance adhesion of precursors to the substrate, their precise role in the growth mechanism has rarely been discussed. Here, we report the role of alkali metal promoter in growing monolayer TMDs. The growth occurred via the formation of sodium metal oxides which prevent the evaporation of metal precursor. Furthermore, the silicon oxide substrate helped to decrease the Gibbs free energy by forming sodium silicon oxide compounds. The resulting sodium metal oxide was anchored within such concavities created by corrosion of silicon oxide. Consequently, the wettability of the precursors to silicon oxide was improved, leading to enhance lateral growth of monolayer TMDs.

  15. Alkylamine-tethered stable metal-organic framework for CO(2) capture from flue gas.

    PubMed

    Hu, Yingli; Verdegaal, Wolfgang M; Yu, Shu-Hong; Jiang, Hai-Long

    2014-03-01

    Different alkylamine molecules were post-synthetically tethered to the unsaturated Cr(III) centers in the metal-organic framework MIL-101. The resultant metal-organic frameworks show almost no N2 adsorption with significantly enhanced CO2 capture under ambient conditions as a result of the interaction between amine groups and CO2 molecules. Given the extraordinary stability, high CO2 uptake, ultrahigh CO2 /N2 selectivity, and mild regeneration energy, MIL-101-diethylenetriamine holds exceptional promise for post-combustion CO2 capture and CO2 /N2 separation.

  16. A new metalation complex for organic synthesis and polymerization reactions

    NASA Technical Reports Server (NTRS)

    Hirshfield, S. M.

    1971-01-01

    Organometallic complex of N,N,N',N' tetramethyl ethylene diamine /TMEDA/ and lithium acts as metalation intermediate for controlled systhesis of aromatic organic compounds and polymer formation. Complex of TMEDA and lithium aids in preparation of various organic lithium compounds.

  17. Asymmetric organic/metal(oxide) hybrid nanoparticles: synthesis and applications.

    PubMed

    He, Jie; Liu, Yijing; Hood, Taylor C; Zhang, Peng; Gong, Jinlong; Nie, Zhihong

    2013-06-21

    Asymmetric particles (APs) with broken centrosymmetry are of great interest, due to the asymmetric surface properties and diverse functionalities. In particular, organic/metal(oxide) APs naturally combine the significantly different and complementary properties of organic and inorganic species, leading to their unique applications in various fields. In this review article, we highlighted recent advances in the synthesis and applications of organic/metal(oxide) APs. This type of APs is grounded on chemical or physical interactions between metal(oxide) NPs and organic small molecular or polymeric ligands. The synthetic methodologies were summarized in three categories, including the selective surface modifications, phase separation of mixed ligands on the surface of metal(oxide) NPs, and direct synthesis of APs. We further discussed the unique applications of organic/metal(oxide) APs in self-assembly, sensors, catalysis, and biomedicine, as a result of the distinctions between asymmetrically distributed organic and inorganic components. Finally, challenges and future directions are discussed in an outlook section.

  18. Asymmetric organic/metal(oxide) hybrid nanoparticles: synthesis and applications

    NASA Astrophysics Data System (ADS)

    He, Jie; Liu, Yijing; Hood, Taylor C.; Zhang, Peng; Gong, Jinlong; Nie, Zhihong

    2013-05-01

    Asymmetric particles (APs) with broken centrosymmetry are of great interest, due to the asymmetric surface properties and diverse functionalities. In particular, organic/metal(oxide) APs naturally combine the significantly different and complementary properties of organic and inorganic species, leading to their unique applications in various fields. In this review article, we highlighted recent advances in the synthesis and applications of organic/metal(oxide) APs. This type of APs is grounded on chemical or physical interactions between metal(oxide) NPs and organic small molecular or polymeric ligands. The synthetic methodologies were summarized in three categories, including the selective surface modifications, phase separation of mixed ligands on the surface of metal(oxide) NPs, and direct synthesis of APs. We further discussed the unique applications of organic/metal(oxide) APs in self-assembly, sensors, catalysis, and biomedicine, as a result of the distinctions between asymmetrically distributed organic and inorganic components. Finally, challenges and future directions are discussed in an outlook section.

  19. Metal-Organic Frameworks for Highly Selective Separations

    SciTech Connect

    Omar M. Yaghi

    2009-09-28

    This grant was focused on the study of metal-organic frameworks with these specific objectives. (1) To examine the use of MOFs with well-defined open metal sites for binding of gases and small organics. (2) To develop a strategy for producing MOFs that combine large pore size with high surface area for their use in gas adsorption and separation of polycyclic organic compounds. (3) To functionalize MOFs for the storage of inert gases such as methane. A brief outline of our progress towards these objectives is presented here as it forms part of the basis for the ideas to be developed under the present proposal.

  20. Melt-Quenched Hybrid Glasses from Metal-Organic Frameworks.

    PubMed

    Tao, Haizheng; Bennett, Thomas D; Yue, Yuanzheng

    2017-05-01

    While glasses formed by quenching the molten states of inorganic non-metallic, organic, and metallic species are known, those containing both inorganic and organic moieties are far less prevalent. Network materials consisting of inorganic nodes linked by organic ligands do however exist in the crystalline or amorphous domain. This large family of open framework compounds, called metal-organic frameworks (MOFs) or coordination polymers, has been investigated intensively in the past two decades for a variety of applications, almost all of which stem from their high internal surface areas and chemical versatility. Recently, a selection of MOFs has been demonstrated to undergo melting and vitrification upon cooling. Here, these recent discoveries and the connections between the fields of MOF chemistry and glass science are summarized. Possible advantages and applications for MOF glasses produced by utilizing the tunable chemistry of the crystalline state are also highlighted. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Surface modification of hollow magnetic Fe3O4@NH2-MIL-101(Fe) derived from metal-organic frameworks for enhanced selective removal of phosphates from aqueous solution

    PubMed Central

    Li, Yan; Xie, Qiying; Hu, Qian; Li, Chengping; Huang, Zhangjie; Yang, Xiangjun; Guo, Hong

    2016-01-01

    Hollow magnetic Fe3O4@NH2-MIL-101(Fe) derived from metal-organic frameworks are fabricated through a general facile strategy. The synthetic parameters are regulated to control the shape of the as-prepared samples. The concentration of phosphates decreased sharply from the initial 0.60 to 0.045 mg.L−1 with the exposure time in 50 minutes. The correlation between the most significant parameters such as contact time, adsorbent dose, pH, as well as adsorption capacities was optimized, and the effects of these parameters on the removal efficiency of phosphates were investigated. Surface functionalization of magnetic hollow materials is a well-designed way to bridge the gap between high adsorption activity, excellent separation and recovery of phosphates from the water treatment system. Therefore, it exhibits a remarkable selective removal of phosphates from aqueous solution. PMID:27470443

  2. Surface modification of hollow magnetic Fe3O4@NH2-MIL-101(Fe) derived from metal-organic frameworks for enhanced selective removal of phosphates from aqueous solution

    NASA Astrophysics Data System (ADS)

    Li, Yan; Xie, Qiying; Hu, Qian; Li, Chengping; Huang, Zhangjie; Yang, Xiangjun; Guo, Hong

    2016-07-01

    Hollow magnetic Fe3O4@NH2-MIL-101(Fe) derived from metal-organic frameworks are fabricated through a general facile strategy. The synthetic parameters are regulated to control the shape of the as-prepared samples. The concentration of phosphates decreased sharply from the initial 0.60 to 0.045 mg.L-1 with the exposure time in 50 minutes. The correlation between the most significant parameters such as contact time, adsorbent dose, pH, as well as adsorption capacities was optimized, and the effects of these parameters on the removal efficiency of phosphates were investigated. Surface functionalization of magnetic hollow materials is a well-designed way to bridge the gap between high adsorption activity, excellent separation and recovery of phosphates from the water treatment system. Therefore, it exhibits a remarkable selective removal of phosphates from aqueous solution.

  3. Surface-plasmon-enhanced photoconversion in organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Morfa, Anthony John

    In this thesis, the benefits of including surface-plasmon-active materials into organic photovoltaics are investigated. First, the effect of discontinuous silver thin-films formed by physical vapor deposition at the transparent front electrode of the device is explored. A reproducible near doubling in efficiency is seen in these devices which arises from a near doubling of the short-circuit current. Analysis of the wavelength-dependence of the increase in current shows that the increase in current is due to surface-plasmon-enhanced optical absorption in the active layer of the devices. Additionally, these results are shown to be reproducible over several trials when using a fabrication routine that employs a low-temperature annealing step that retains the surface-plasmon activity of the substrate and prevents delamination of the active layers. The relative dielectric function of the active-layer material was determined at optical frequencies using variable-angle spectroscopic ellipsometry. A Huang-Rhys vibronic progression is used to model the peak energies of excitonic transitions in the film and the resulting parameters are found to be in excellent agreement with previously reported values. Theoretical calculations of the surface-plasmon enhancement are performed using the aforementioned dielectric function. The theoretical calculation of the skin depth of the surface plasmon is shown to be consistent with the observed wavelength dependence of the plasmonically enhanced current in organic photodiodes. In order to better understand the enhancement process and the fate of photogenerated holes and electrons, additional work was done to explore the electronic structure of the organic films using impedance spectroscopy. The results of this work indicate the presence of a Schottky diode at the metal/organic interface in standard device geometries. This result has several implications on charge extraction for standard devices and those including silver thin-films. It is

  4. Metal Nanoshells for Plasmonically Enhanced Solar to Fuel Photocatalytic Conversion

    DTIC Science & Technology

    2016-05-18

    AFRL-AFOSR-JP-TR-2016-0075 Metal Nanoshells for Plasmonically Enhanced Solar to Fuel Photocatalytic Conversion Randall Lee UNIVERSITY OF HOUSTON... Solar to Fuel Photocatalytic Conversion 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-14-1-4074 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Randall...redistribution of the absorbed energy via various dissipative mechanisms. This energy transfer can enhance the photoactivity of the system because ZIS

  5. Design and synthesis of metal-organic frameworks using metal-organic polyhedra as supermolecular building blocks.

    PubMed

    Perry, John J; Perman, Jason A; Zaworotko, Michael J

    2009-05-01

    This critical review highlights supermolecular building blocks (SBBs) in the context of their impact upon the design, synthesis, and structure of metal-organic materials (MOMs). MOMs, also known as coordination polymers, hybrid inorganic-organic materials, and metal-organic frameworks, represent an emerging class of materials that have attracted the imagination of solid-state chemists because MOMs combine unprecedented levels of porosity with a range of other functional properties that occur through the metal moiety and/or the organic ligand. First generation MOMs exploited the geometry of metal ions or secondary building units (SBUs), small metal clusters that mimic polygons, for the generation of MOMs. In this critical review we examine the recent (<5 years) adoption of much larger scale metal-organic polyhedra (MOPs) as SBBs for the construction of MOMs by highlighting how the large size and high symmetry of such SBBs can afford improved control over the topology of the resulting MOM and a new level of scale to the resulting framework (204 references).

  6. Multiphoton absorption in graphene and metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Weiqiang, Chen

    Materials possessing large multiphoton absorption are of direct relevance to both photonics applications and materials physics. In this dissertation, we present our investigations into two novel materials: namely, (1) graphene and (2) metal-organic frameworks (MOFs). The dissertation divides into two parts. The first part of the dissertation reports our systematical Z-scan measurements onto two-photon absorption (2PA) in graphene in the spectral range of 435-1100 nm with femtosecond laser pulses. We report that the measured 2PA coefficients of graphene in the near-infrared (NIR) range of 800-1100 nm can be explained by a theoretical model based on the optical transitions near the Dirac point (K point). We also determine the 2PA coefficients of graphene in the visible spectrum (435-700 nm) and observe an enhancement induced by the excitonic Fano resonance at the saddle point (M point). By applying the second-order, time-dependent perturbation theory on interband transitions among three states near the saddle point, we develop a semi-empirical model to take excitons in graphene into consideration. And the model is in agreement with the photon-energy dependence of the observed 2PA spectrum with a scaling factor of B = (1 5) x 102 cm/MW/eV5. Our results verify, for the first time, that the excitonic Fano resonance plays an important role for the 2PA of graphene in the visible spectrum. Besides, we also detail our measurements on the spectral dependence of one-photon absorption (1PA) saturation in graphene over the visible-NIR range. A quadratic photon energy dependence of the measured saturation intensity/fluence is observed over the investigated spectral range. The underlying photo-dynamics is discussed. In the second part of the dissertation, we investigate multiphoton excited photoluminescence (MEPL) from three solid-state crystals of metal-organic frameworks (MOFs): (1) [Zn2(trans,trans-4,4 stilbenedicarboxylic acid (SDC))2(trans, trans-9, 10-bis (4-pyridylethenyl

  7. Enhancement of metal bioleaching from contaminated sediment using silver ion.

    PubMed

    Chen, Shen-Yi; Lin, Jih-Gaw

    2009-01-30

    A silver-catalyzed bioleaching process was used to remove heavy metals from contaminated sediment in this study. The effects of silver concentration added on the performance of bioleaching process were investigated. High pH reduction rate was observed in the bioleaching process with silver ion. The silver ion added in the bioleaching process was incorporated into the lattice of the initial sulfide through a cationic interchange reaction. This resulted in the short lag phase and high metal solubilization in the bioleaching process. The maximum pH reduction rate and the ideal metal solubilization were obtained in the presence of 30 mg/L of silver ion. When the added silver ion was greater than 30 mg/L, the rates of pH reduction and metal solubilization gradually decreased. The solubilization efficiencies of heavy metals (Cu, Zn, Mn, Ni and Cr) were relatively high in the silver-enhanced bioleaching process, except Pb. No apparent effect of silver ion on the growth of sulfur-oxidizing bacteria was found in the bioleaching. These results indicate that the kinetics of metal solubilization can be enhanced by the addition of silver ion.

  8. Broadband enhanced transmission of acoustic waves through serrated metal gratings

    NASA Astrophysics Data System (ADS)

    Qi, Dong-Xiang; Deng, Yu-Qiang; Xu, Di-Hu; Fan, Ren-Hao; Peng, Ru-Wen; Chen, Ze-Guo; Lu, Ming-Hui; Huang, X. R.; Wang, Mu

    2015-01-01

    In this letter, we have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the acoustic transmission properties of metal gratings with or without serrated boundaries. The average transmission is obviously enhanced for serrated metal gratings within a wide frequency range, while the Fabry-Perot resonance is significantly suppressed. An effective medium hypothesis with varying acoustic impedance is proposed to analyze the mechanism, which was verified through comparison with finite-element simulation. The serrated boundary supplies gradient mass distribution and gradient normal acoustic impedance, which could efficiently reduce the boundary reflection. Further, by increasing the region of the serrated boundary, we present a broadband high-transmission grating for wide range of incident angle. Our results may have potential applications to broadband acoustic imaging, acoustic sensing, and acoustic devices.

  9. Metallacarboranes: Towards promising hydrogen storage metal organic framework

    NASA Astrophysics Data System (ADS)

    Singh, Abhishek; Sadrzadeh, Arta; Yakobson, Boris

    2011-03-01

    Using first principles calculations we show the high hydrogen storage capacity of metallacarboranes, where the transition metal (TM) atoms bind hydrogen via Kubas interaction. The average binding energy of ~ 0.3 eV/H favorably lies within the reversible adsorption range The Sc and Ti are found to be the optimum metal atoms maximizing the number of stored H2 molecules. Depending upon the structure, metallacarboranes can adsorb up to 8 wt% of hydrogen, which exceeds DOE goal for 2015. Being integral part of the cage, TMs do not suffer from the aggregation problem. Furthermore, the presence of carbon atom in the cages permits linking the metallacarboranes to form metal organic frameworks (MOF), thus able to adsorb hydrogen via Kubas interaction, in addition to van der Waals physisorption. A. K. Singh, A. Sadrzadeh, and B. I. Yakobson, Metallacarboranes: Toward Promising Hydrogen Storage Metal Organic Frameworks, JACS 132,14126 (2010).

  10. Enhanced-electrokinetic extraction of heavy metals from dredged harbor sediment.

    PubMed

    Yoo, Jong-Chan; Yang, Jung-Seok; Jeon, Eun-Ki; Baek, Kitae

    2015-07-01

    In this study, the feasibility of an ex situ electrokinetic (EK) process combined with pre-oxidation using hydrogen peroxide (H2O2) and pre-washing using ethylenediaminetetraacetic acid (EDTA) was investigated in enhancing the extraction of Cu, Pb, and Zn from actual dredged harbor sediment. H2O2 pre-oxidation led to a change in the fractionation of Cu bound to organic matter and the sulfide fraction in the Fe-Mn oxides to the exchangeable fraction, but was not effective at removing metals. In contrast, EDTA pre-washing changed the Fe-Mn oxide-bound fractions of Cu and Pb into easily extractable fractions; 20.1, 27.5, and 32.8% of Cu, Pb, and Zn were removed, respectively. During EK treatment, metals were transported toward the anode by electromigration of negatively charged complexes such as metal-EDTA and metal-citrate. However, EK treatment did not significantly enhance the removal of metals because metals accumulated near the anodic region with an increase in the exchangeable fraction due to the short EK operating duration and low voltage gradient. Therefore, it is necessary to extend the EK operating duration and/or increase the voltage gradient for effective transportation and removal of metals from sediment.

  11. Exciton-Plasmon Coupling Enhancement via Metal Oxidation.

    PubMed

    Todisco, Francesco; D'Agostino, Stefania; Esposito, Marco; Fernández-Domínguez, Antonio I; De Giorgi, Milena; Ballarini, Dario; Dominici, Lorenzo; Tarantini, Iolena; Cuscuná, Massimo; Della Sala, Fabio; Gigli, Giuseppe; Sanvitto, Daniele

    2015-10-27

    In this paper, we report on the effect of metal oxidation on strong coupling interactions between silver nanostructures and a J-aggregated cyanine dye. We show that metal oxidation can sensibly affect the plexcitonic system, inducing a change in the coupling strength. In particular, we demonstrate that the presence of oxide prevents the appearance of Rabi splitting in the extinction spectra for thick spacers. In contrast, below a threshold percentage, the oxide layer results in an higher coupling strength between the plasmon and the Frenkel exciton. Contrary to common belief, a thin oxide layer seems thus to act, under certain conditions, as a coupling mediator between an emitter and a localized surface plasmon excited in a metallic nanostructure. This suggests that metal oxidation can be exploited as a means to enhance light-matter interactions in strong coupling applications.

  12. Mechanochemical synthesis of an yttrium based metal-organic framework.

    PubMed

    Singh, Niraj K; Hardi, Meenakshi; Balema, Viktor P

    2013-02-01

    For the first time a metal hydride has been used for the preparation of a metal-organic framework. MIL-78 has been synthesized by the solid-state mechanochemical reaction between yttrium hydride and trimesic acid. The process does not involve solvents and does not generate liquid by-products, thus proving the viability of the solid-state approach to the synthesis of MOFs.

  13. Ionic Transport Through Metal-Rich Organic Coatings

    DTIC Science & Technology

    2016-08-19

    volume (MPV) percent, solvent polarity, and resin molecular weight impact corrosion protection of metal-rich organic (MRO) coatings. Following design...Preliminary tests indicate that the effects of MPV percent, solvent polarity, and resin molecular weight can be measured using a modified Hitorff...protective nature are not fully understood. This paper investigates how metal particle volume (MPV) percent, solvent polarity, and resin molecular

  14. Ionic Transport Through Metal-Rich Organic Coatings

    DTIC Science & Technology

    2016-08-19

    volume (MPV) percent, solvent polarity, and resin molecular weight impact corrosion protection of metal-rich organic (MRO) coatings. Following design of...Preliminary tests indicate that the effects of MPV percent, solvent polarity, and resin molecular weight can be measured using a modified Hitorff cell...protective nature are not fully understood. This paper investigates how metal particle volume (MPV) percent, solvent polarity, and resin molecular weight

  15. Selective fluorescence sensors for detection of nitroaniline and metal Ions based on ligand-based luminescent metal-organic frameworks

    SciTech Connect

    Yu, Zongchao; Wang, Fengqin; Lin, Xiangyi; Wang, Chengmiao; Fu, Yiyuan; Wang, Xiaojun; Zhao, Yongnan; Li, Guodong

    2015-12-15

    Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)–based metal-organic frameworks, Zn{sub 3}L{sub 3}(DMF){sub 2} (1) and Zn{sub 3}L{sub 3}(DMA){sub 2}(H{sub 2}O){sub 3} (2) (L=4,4′-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe{sup 3+} and Al{sup 3+} by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significant fluorescence quenching effect for Fe{sup 3+}. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity. - Graphical abstract: Two MOFs have been selected as the fluorescence sensing materials for selectively sensing mitroaromatic compounds and metal ions. The high selectivity makes them promising fluorescence sensors for detecting and recognizing nitroaniline and Fe{sup 3+} or Al{sup 3+}.

  16. Mechanisms of enhanced mobilisation of trace metals by anionic surfactants in soil.

    PubMed

    Hernández-Soriano, Maria del Carmen; Degryse, Fien; Smolders, Erik

    2011-03-01

    Long-term applications of small concentrations of surfactants in soil via wastewater irrigation or pesticide application may enhance trace metal solubility. Mechanisms by which anionic surfactants (Aerosol 22, SDS and Biopower) affect trace metal solubility were assessed using batch, incubation and column experiments. In batch experiments on seven soils, the concentrations of Cu, Cd, Ni and Zn in the dissolved fraction of soils increased up to 100-fold at the high application rates, but increased less than 1.5-fold below the critical micelle concentration. Dissolved metal concentrations were less than 20% affected by surfactants in long-term incubations (70 days) up to the largest dose of 200 mg C kg(-1) soil. Leaching soil columns with A22 (100-1000 mg C L(-1)) under unsaturated conditions increased trace metal concentrations in the leachates 2-4 fold over the control. Correlation analysis and speciation modelling showed that the increased solubility of metals upon surfactant application was more related to the solubilisation of soil organic matter from soil than to complexation of the metals with the surfactant. Organic matter from soil was solubilised in response to a decrease of solution Ca(2+) as a result of Ca-surfactant precipitation. At environmentally relevant concentrations, surfactant application is unlikely to have a significant effect on trace metal mobility.

  17. Inorganic Metal Oxide/Organic Polymer Nanocomposites And Method Thereof

    DOEpatents

    Gash, Alexander E.; Satcher, Joe H.; Simpson, Randy

    2004-11-16

    A synthetic method for preparation of hybrid inorganic/organic energetic nanocomposites is disclosed herein. The method employs the use of stable metal in organic salts and organic solvents as well as an organic polymer with good solubility in the solvent system to produce novel nanocomposite energetic materials. In addition, fuel metal powders (particularly those that are oxophilic) can be incorporated into composition. This material has been characterized by thermal methods, energy-filtered transmission electron microscopy (EFTEM), N.sub.2 adsoprtion/desorption methods, and Fourier-Transform (FT-IR) spectroscopy. According to these characterization methods the organic polymer phase fills the nanopores of the material, providing superb mixing of the component phases in the energetic nanocomposite.

  18. Metal Organic-Chemical Vapor Deposition fabrication of semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Thomas, C.

    1980-08-01

    The metal organic chemical vapor deposition (MO-CVD) process was studied and implemented in detail. Single crystal GaAs, and Ga(x)Al(1-x)As films were grown on GaAs by depositing metal organic alkyl gallium compounds in the presence of an arsine mixture. The metal organic chemical vapor deposition process allowed formation of the semiconductor compound directly on the heated substrate in only one hot temperature zone. With MO-CVD, semiconductor films can be efficiently produced by a more economical, less complicated process which will lend itself more easily than past fabrication procedures, to high quantity, high quality reproduction techniques of semiconductor lasers. Clearly MO-CVD is of interest to the communication industry where semiconductor lasers are used extensively in fiber optic communication systems, and similarly to the solar energy business where GaAs substrates are used as photoelectric cells.

  19. Plasmonic-enhanced organic solar cells

    NASA Astrophysics Data System (ADS)

    Shahin, Shiva; Gangopadhyay, Palash; Norwood, Robert

    2012-10-01

    Organic bulk-heterojunction solar cells have several good characteristics, such as ease of fabrication, and low-cost materials. However, the bottleneck in their adoption is their much lower efficiency as compared with their silicon counterparts. In our previous work, we demonstrated that by appropriately inserting AuNPs in the OPV device, the efficiency can be increased by 30% and that silanization of ITO positively impacts device performance, where we identified the field enhancement due to AuNPs as the main reason for the increase in the efficiency of the device. In this work, we further investigate the impact of self-assembly of the gold nanoparticles on the efficiency by also considering two other factors which can possibly contribute to the improvement of our structure's performance. One is the change in the substrate's workfunction after silanization, and the other factor is the variations in PEDOT: PSS characteristics due to the AuNPs' plasmonic resonance. We conclude that the AuNPs not only increase the photon absorption efficiency but also increase the conductivity of the surrounding medium (PEDOT: PSS) thereby facilitating charge transport through PEDOT: PSS.

  20. Nonlinear optical properties of Pb-La metal-organic chelidamic acid frameworks

    NASA Astrophysics Data System (ADS)

    Tan, Min; Chen, Ruiqi; Yang, Sanjun; Liu, Qiming

    2017-04-01

    Chelidamic acid, acting as ligands, reacted with metal cation of lead and lanthanum. Both of them were dissolved in water and resulted in novel MOFs complexes by using solvothermal synthesis method. The complexes were characterized by the X-ray diffraction, UV-vis spectrophotometer and Z-scan measurements to investigate their morphology and optical properties. The Z-scan measurements indicated that the obtained lead metal-organic chelidamic acid frameworks showed 6.09 × 10-12 esu of χ(3). The special structure and properties, especially the empty f-electron orbital of the rare earth elements, were used to enhance optical nonlinearity. Using one-step solvothermal synthesis method, we added lanthanum into the lead-chelidamic acid metal organic complexes. By changing the spatial configuration of the ligand in the self-assembly process, novel structural complex metals of the lead-lanthanum metal-organic chelidamic acid frameworks have been successfully synthetized, and the third-order nonlinear susceptibility of χ(3)was enhanced to be 1.13 × 10-11 esu.

  1. Energy Storage during Compression of Metal-Organic Frameworks.

    PubMed

    Miao, Yu-Run; Su, Zhi; Suslick, Kenneth S

    2017-04-05

    Practical applications of metal-organic framework (MOF) materials require an in-depth understanding of their mechanical properties. We have investigated the mechanical properties and energy absorption behavior of single crystals of four isostructural UiO-type MOFs under uniaxial compression. In situ nanocompression experiments were used to measure the mechanical behavior of individual MOF nanocrystals under compression within a transmission electron microscope. The plasticity and endothermicity during deformation of MOFs shows a surprising potential for absorption and dissipation of mechanical shock. At compressive stress below 2 GPa, relatively small amounts of energy (<0.3 kJ/g) are absorbed by the compression of these MOFs. As the stress was increased, however, the energy absorption was significantly enhanced. Above 2 GPa, the energy absorption typically reaches 3-4 kJ/g; for comparison, the energy release in the explosion of TNT is ∼4 kJ/g. Gram for gram, MOFs can absorb as much energy as a high explosive can release.

  2. Heavy metals, organics and radioactivity in soil of western Serbia.

    PubMed

    Dugalic, Goran; Krstic, Dragana; Jelic, Miodrag; Nikezic, Dragoslav; Milenkovic, Biljana; Pucarevic, Mira; Zeremski-Skoric, Tijana

    2010-05-15

    Western Serbia is a region well-known for potato production. Concentrations of selected metals, polycyclic aromatic hydrocarbons (PAHs) and radioactivity were measured in the soil in order to evaluate the quality and characteristics. The examined soils (Luvisol and Pseudogley) showed unsuitable agrochemical characteristics (acid reaction, low content of organic matter and potassium). Some samples contained Ni, Mn and Cr above the maximal permissible concentration (MPC). The average concentration of total PAHs was 1.92 mg/kg, which is larger than the maximal permissible concentration in Serbia but below the threshold values in the European Union for food production. The average radioactivity of (238)U, (226)Ra, (232)Th, (40)K and the fission product (137)Cs were 60.4+/-26.2, 33.2+/-13.4, 49.1+/-18.5, 379+/-108 and 36.4+/-23.3 Bq/kg. Enhanced radioactivity in the soils was found. The total absorbed dose rate in air above the soil at 1m height calculated for western Serbia was 73.4 nGy/h and the annual effective dose was 90 microSv, which are similar to earlier reports for the study region.

  3. Broadband short-range surface plasmon structures for absorption enhancement in organic photovoltaics.

    PubMed

    Bai, Wenli; Gan, Qiaoqiang; Song, Guofeng; Chen, Lianghui; Kafafi, Zakya; Bartoli, Filbert

    2010-11-08

    We theoretically demonstrate a polarization-independent nanopatterned ultra-thin metallic structure supporting short-range surface plasmon polariton (SRSPP) modes to improve the performance of organic solar cells. The physical mechanism and the mode distribution of the SRSPP excited in the cell device were analyzed, and reveal that the SRSPP-assisted broadband absorption enhancement peak could be tuned by tailoring the parameters of the nanopatterned metallic structure. Three-dimensional finite-difference time domain calculations show that this plasmonic structure can enhance the optical absorption of polymer-based photovoltaics by 39% to 112%, depending on the nature of the active layer (corresponding to an enhancement in short-circuit current density by 47% to 130%). These results are promising for the design of organic photovoltaics with enhanced performance.

  4. Optimal design of resonant enhanced quantum dot infrared photodetector based on metal-insulator-metal microcavity

    NASA Astrophysics Data System (ADS)

    Wang, Han; Jing, Youliang; Li, Mengyao; Li, Liang; Zhen, Honglou

    2015-11-01

    The design of quantum dot infrared photodetector (QDIP) based on metal-insulator-metal (MIM) microcavity in which the quantum dot (QD) is sandwiched between a planar metallic film and a metallic stripe is reported. By a finite difference time-domain (FDTD) method, the light coupling efficiency spectra and enhancement factor are numerically calculated. The results exhibit that the total electric field concentrated in metal-metal region is strongly enhanced when the resonant frequency of microcavity is equal to the QD's peak response frequency. This enhancement effect mainly originates from the resonant coupling of incident photons into microcavity forming the surface plasmonic mode. The optimization of structural parameters for MIM microcavity is discussed, demonstrating an optimal structure of quantum dot infrared photodetector with the coupling efficiency improved nearly 7 times compared with conventional mesa QDIPs. So, it is deduced that a favorable performance of device such as high quantum efficiency and infrared responsivity is possible. Finally, the detector shows the potential application in the infrared sensing and imaging, as well as integrating with other electronic and optoelectronic device for the sub-wavelength size.

  5. Metal hybrid nanoparticles for catalytic organic and photochemical transformations.

    PubMed

    Song, Hyunjoon

    2015-03-17

    In order to understand heterogeneous catalytic reactions, model catalysts such as a single crystalline surface have been widely studied for many decades. However, catalytic systems that actually advance the reactions are three-dimensional and commonly have multiple components including active metal nanoparticles and metal oxide supports. On the other hand, as nanochemistry has rapidly been developed and been applied to various fields, many researchers have begun to discuss the impact of nanochemistry on heterogeneous catalysis. Metal hybrid nanoparticles bearing multiple components are structurally very close to the actual catalysts, and their uniform and controllable morphology is suitable for investigating the relationship between the structure and the catalytic properties in detail. In this Account, we introduce four typical structures of metal hybrid nanoparticles that can be used to conduct catalytic organic and photochemical reactions. Metal@silica (or metal oxide) yolk-shell nanoparticles, in which metal cores exist in internal voids surrounded by thin silica (or metal oxide) shells, exhibited extremely high thermal and chemical stability due to the geometrical protection of the silica layers against the metal cores. The morphology of the metal cores and the pore density of the hollow shells were precisely adjusted to optimize the reaction activity and diffusion rates of the reactants. Metal@metal oxide core-shell nanoparticles and inverted structures, where the cores supported the shells serving an active surface, exhibited high activity with no diffusion barriers for the reactants and products. These nanostructures were used as effective catalysts for various organic and gas-phase reactions, including hydrogen transfer, Suzuki coupling, and steam methane reforming. In contrast to the yolk- and core-shell structures, an asymmetric arrangement of distinct domains generated acentric dumbbells and tipped rods. A large domain of each component added multiple

  6. Heavy Metal Pollution Enhances Soil Respiration and Reduces Carbon Storage in a Chinese Paddy Soil

    NASA Astrophysics Data System (ADS)

    Pan, Genxing; Li, Zhipeng; Liu, Yongzhuo; Smith, Pete; Crowley, David; Zheng, Jufeng

    2010-05-01

    China's paddy soils are crucial both for food security through high cereal productivity, and for climate mitigation through high soil carbon storage. These functions are increasingly threatened by widespread heavy metal pollution, resulting from rapid industrial development. Heavy metal-polluted soils generally have a reduced microbial biomass and reduced soil respiration, as well as reduced functional diversity through changes in microbial community structure. Here we show that heavy metal pollution enhances soil respiration and CO2 efflux from a Chinese rice paddy soil, and leads to a soil organic carbon (SOC) loss, which is correlated with a decline in the fungal-to-bacterial ratio of the reduced soil microbial community. The pollution-induced SOC loss could offset 70% of the yearly SOC increase from China's paddy soils. Thus, heavy metal pollution impacts long term productivity and the potential for C sequestration in China's paddy soils.

  7. Species sensitivity analysis of heavy metals to freshwater organisms.

    PubMed

    Xin, Zheng; Wenchao, Zang; Zhenguang, Yan; Yiguo, Hong; Zhengtao, Liu; Xianliang, Yi; Xiaonan, Wang; Tingting, Liu; Liming, Zhou

    2015-10-01

    Acute toxicity data of six heavy metals [Cu, Hg, Cd, Cr(VI), Pb, Zn] to aquatic organisms were collected and screened. Species sensitivity distributions (SSD) curves of vertebrate and invertebrate were constructed by log-logistic model separately. The comprehensive comparisons of the sensitivities of different trophic species to six typical heavy metals were performed. The results indicated invertebrate taxa to each heavy metal exhibited higher sensitivity than vertebrates. However, with respect to the same taxa species, Cu had the most adverse effect on vertebrate, followed by Hg, Cd, Zn and Cr. When datasets from all species were included, Cu and Hg were still more toxic than the others. In particular, the toxicities of Pb to vertebrate and fish were complicated as the SSD curves of Pb intersected with those of other heavy metals, while the SSD curves of Pb constructed by total species no longer crossed with others. The hazardous concentrations for 5 % of the species (HC5) affected were derived to determine the concentration protecting 95 % of species. The HC5 values of the six heavy metals were in the descending order: Zn > Pb > Cr > Cd > Hg > Cu, indicating toxicities in opposite order. Moreover, potential affected fractions were calculated to assess the ecological risks of different heavy metals at certain concentrations of the selected heavy metals. Evaluations of sensitivities of the species at various trophic levels and toxicity analysis of heavy metals are necessary prior to derivation of water quality criteria and the further environmental protection.

  8. Effect of clays, metal oxides, and organic matter on rhamnolipid biosurfactant sorption by soil.

    PubMed

    Ochoa-Loza, Francisco J; Noordman, Wouter H; Jannsen, Dick B; Brusseau, Mark L; Maier, Raina M

    2007-01-01

    Rhamnolipids produced by Pseudomonas aeruginosa have been proposed as soil washing agents for enhanced removal of metal and organic contaminants from soil. A potential limitation for the application of rhamnolipids is sorption by soil matrix components. The objective of this study is to empirically determine the contribution of representative soil constituents (clays, metal oxides, and organic matter) to sorption of the rhamnolipid form most efficient at metal complexation (monorhamnolipid). Sorption studies show that monorhamnolipid (R1) sorption is concentration dependent. At low R1 concentrations that are relevant for enhancing organic contaminant biodegradation, R1 sorption followed the order: hematite (Fe(2)O(3))>kaolinite>MnO(2) approximately illite approximately Ca-montmorillonite>gibbsite (Al(OH)(3))>humic acid-coated silica. At high R1 concentrations, relevant for use in complexation/removal of metals or organics, R1 sorption followed the order: illite>humic acid-coated silica>Ca-montmorillonite>hematite>MnO(2)>gibbsite approximately kaolinite. These results allowed prediction of R1 sorption by a series of six soils. Finally, a comparison of R1 and R2 (dirhamnolipid) shows that the R1 form sorbs more strongly alone than when in a mixture of both the R1 and R2 forms. The information presented can be used to estimate, on an individual soil basis, the extent of rhamnolipid sorption. This is important for determining: (1) whether rhamnolipid addition is a feasible remediation option and (2) the amount of rhamnolipid required to efficiently remove the contaminant.

  9. Solution-Processed Metal Oxides as Efficient Carrier Transport Layers for Organic Photovoltaics.

    PubMed

    Choy, Wallace C H; Zhang, Di

    2016-01-27

    Carrier (electron and hole) transport layers (CTLs) are essential components for boosting the performance of various organic optoelectronic devices such as organic solar cells and organic light-emitting diodes. Considering the drawbacks of conventional CTLs (easily oxidized/unstable, demanding/costly fabrication, etc.), transition metal oxides with good carrier transport/extraction and superior stability have drawn extensive research interest as CTLs for next-generation devices. In recent years, many research efforts have been made toward the development of solution-based metal oxide CTLs with the focus on low- or even room-temperature processes, which can potentially be compatible with the deposition processes of organic materials and can significantly contribute to the low-cost and scale-up of organic devices. Here, the recent progress of different types of solution-processed metal oxide CTLs are systematically reviewed in the context of organic photovoltaics, from synthesis approaches to device performance. Different approaches for further enhancing the performance of solution-based metal oxide CTLs are also discussed, which may push the future development of this exciting field.

  10. Metal-Organic Frameworks as Platforms for Functional Materials.

    PubMed

    Cui, Yuanjing; Li, Bin; He, Huajun; Zhou, Wei; Chen, Banglin; Qian, Guodong

    2016-03-15

    Discoveries of novel functional materials have played very important roles to the development of science and technologies and thus to benefit our daily life. Among the diverse materials, metal-organic framework (MOF) materials are rapidly emerging as a unique type of porous and organic/inorganic hybrid materials which can be simply self-assembled from their corresponding inorganic metal ions/clusters with organic linkers, and can be straightforwardly characterized by various analytical methods. In terms of porosity, they are superior to other well-known porous materials such as zeolites and carbon materials; exhibiting extremely high porosity with surface area up to 7000 m(2)/g, tunable pore sizes, and metrics through the interplay of both organic and inorganic components with the pore sizes ranging from 3 to 100 Å, and lowest framework density down to 0.13 g/cm(3). Such unique features have enabled metal-organic frameworks to exhibit great potentials for a broad range of applications in gas storage, gas separations, enantioselective separations, heterogeneous catalysis, chemical sensing and drug delivery. On the other hand, metal-organic frameworks can be also considered as organic/inorganic self-assembled hybrid materials, we can take advantages of the physical and chemical properties of both organic and inorganic components to develop their functional optical, photonic, and magnetic materials. Furthermore, the pores within MOFs can also be utilized to encapsulate a large number of different species of diverse functions, so a variety of functional MOF/composite materials can be readily synthesized. In this Account, we describe our recent research progress on pore and function engineering to develop functional MOF materials. We have been able to tune and optimize pore spaces, immobilize specific functional groups, and introduce chiral pore environments to target MOF materials for methane storage, light hydrocarbon separations, enantioselective recognitions

  11. Metals in sediments and benthic organisms in the Mersey estuary

    NASA Astrophysics Data System (ADS)

    Langston, W. J.

    1986-08-01

    Concentrations of twelve metals were determined in sediments, seaweed ( Fucus vesiculosus), winkles ( Littorina littorea), polychaetes ( Nereis diversicolor), suspension feeding bivalves ( Mytilus edulis, Cerastoderma edule) and deposit feeding bivalves ( Macoma balthica, Scrobicularia plana) collected from the Mersey estuary between April 1980 and June 1984. Sediments and organisms in the Mersey are moderately contaminated with most of the metals measured, but mercury concentrations are consistently higher than in other United Kingdom estuaries. Comparisons with other sites in the North West of England indicate that mercury residues in organisms, though primarily dependent on sediment concentrations, are also influenced by complexation with particulate organic matter which reduces the availability of mercury. The biological availability of arsenic in Mersey sediments is similarly influenced by complexation with iron oxyhydroxides. Nereis diversicolor and Macoma balthica are the most suitable indicator species in terms of abundance and widespread distribution along the estuary, and, for the majority of metals, tissue concentrations increase upstream, reflecting corresponding gradients in sediment contamination. However mid-estuarine peaks for tin, chromium copper and nickel in Nereis indicate more localised inputs to the estuary. Correlations between lead in sediments and organisms are poor; it is suggested that hydrophilic alkyl lead compounds may be the predominant biologically available forms. Progressive reductions in mercury contamination in sediments and mercury and lead in organisms have occurred in recent years, which coincide with efforts to reduce inputs of these metals to teh Mersey estuary.

  12. Inorganic metal oxide/organic polymer nanocomposites and method thereof

    DOEpatents

    Gash, Alexander E.; Satcher, Joe H.; Simpson, Randy

    2004-03-30

    A synthetic method for preparation of hybrid inorganic/organic energetic nanocomposites is disclosed herein. The method employs the use of stable metal inorganic salts and organic solvents as well as an organic polymer with good solubility in the solvent system to produce novel nanocomposite energetic materials. In addition, fuel metal powders (particularly those that are oxophillic) can be incorporated into composition. This material has been characterized by thermal methods, energy-filtered transmission electron microscopy (EFTEM), N.sub.2 adsoprtion/desorption methods, and Fourier-Transform (FT-IR) spectroscopy. According to these characterization methods the organic polymer phase fills the nanopores of the composite material, providing superb mixing of the component phases in the energetic nanocomposite.

  13. Enhancement of light absorption in organic solar cells by using plasmonic gratings

    NASA Astrophysics Data System (ADS)

    Xiao, Xiao; Zhang, Zhiyou; Xie, Shiwei; Liu, Yu; Zhai, Yucui; Hu, Dejiao; Du, Jinglei

    2014-11-01

    Organic solar cells show a commercially viable future duo to their inherent advantages, such as light weight, flexibility, and so on. Recently, a lot of progress has been made in every domain of organic solar cells. Among these, plasmonic light trapping is regarded as a promising light management technology for improving the light absorption in organic active layer. In this work, we numerically investigate the light enhancement in organic solar cell by embedding metal gratings as electrodes, including the anode and cathode. The absorption enhancement mechanism is analyzed, and the effects of grating parameters and incident angle are also investigated systematically. The results show the plasmonic gratings, especially the bottom grating, have an obvious improvement for light harvesting in organic layer, and an optical enhancement factor about 100% is obtained.

  14. Performance limits of plasmon-enhanced organic photovoltaics

    SciTech Connect

    Karatay, Durmus U.; Ginger, David S.; Salvador, Michael; Yao, Kai; Jen, Alex K.-Y.

    2014-07-21

    We use a combination of experiment and modeling to explore the promise and limitations of using plasmon-resonant metal nanoparticles to enhance the device performance of organic photovoltaics (OPVs). We focus on optical properties typical of the current generation of low-bandgap donor polymers blended with the fullerene (6,6)-phenyl C{sub 71}-butyric acid methyl ester (PC{sub 71}BM) and use the polymer poly(indacenodithiophene-co-phenanthro[9,10-b]quinoxaline) (PIDT-PhanQ) as our test case. We model the optical properties and performance of these devices both in the presence and absence of a variety of colloidal silver nanoparticles. We show that for these materials, device performance is sensitive to the relative z-position and the density of nanoparticles inside the active layer. Using conservative estimates of the internal quantum efficiency for the PIDT-PhanQ/PC{sub 71}BM blend, we calculate that optimally placed silver nanoparticles could yield an enhancement in short-circuit current density of over 31% when used with ∼ 80-nm-thick active layers, resulting in an absolute increase in power conversion efficiency of up to ∼2% for the device based on optical engineering.

  15. Performance limits of plasmon-enhanced organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Karatay, Durmus U.; Salvador, Michael; Yao, Kai; Jen, Alex K.-Y.; Ginger, David S.

    2014-07-01

    We use a combination of experiment and modeling to explore the promise and limitations of using plasmon-resonant metal nanoparticles to enhance the device performance of organic photovoltaics (OPVs). We focus on optical properties typical of the current generation of low-bandgap donor polymers blended with the fullerene (6,6)-phenyl C71-butyric acid methyl ester (PC71BM) and use the polymer poly(indacenodithiophene-co-phenanthro[9,10-b]quinoxaline) (PIDT-PhanQ) as our test case. We model the optical properties and performance of these devices both in the presence and absence of a variety of colloidal silver nanoparticles. We show that for these materials, device performance is sensitive to the relative z-position and the density of nanoparticles inside the active layer. Using conservative estimates of the internal quantum efficiency for the PIDT-PhanQ/PC71BM blend, we calculate that optimally placed silver nanoparticles could yield an enhancement in short-circuit current density of over 31% when used with ˜ 80-nm-thick active layers, resulting in an absolute increase in power conversion efficiency of up to ˜2% for the device based on optical engineering.

  16. Intrinsic electrical conductivity of nanostructured metal-organic polymer chains

    PubMed Central

    Hermosa, Cristina; Vicente Álvarez, Jose; Azani, Mohammad-Reza; Gómez-García, Carlos J.; Fritz, Michelle; Soler, Jose M.; Gómez-Herrero, Julio; Gómez-Navarro, Cristina; Zamora, Félix

    2013-01-01

    One-dimensional conductive polymers are attractive materials because of their potential in flexible and transparent electronics. Despite years of research, on the macro- and nano-scale, structural disorder represents the major hurdle in achieving high conductivities. Here we report measurements of highly ordered metal-organic nanoribbons, whose intrinsic (defect-free) conductivity is found to be 104 S m−1, three orders of magnitude higher than that of our macroscopic crystals. This magnitude is preserved for distances as large as 300 nm. Above this length, the presence of structural defects (~ 0.5%) gives rise to an inter-fibre-mediated charge transport similar to that of macroscopic crystals. We provide the first direct experimental evidence of the gapless electronic structure predicted for these compounds. Our results postulate metal-organic molecular wires as good metallic interconnectors in nanodevices. PMID:23591876

  17. Charge transport and absorption study of metal nanoparticle plasmonics for organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Xue, Mei; Zhu, Jinfeng; Shen, Huajun; Kim, Seongku; Ho, Jack J.; Qasem, Hussam Aldeen S.; Otaibi, Zaid S. Al; Wang, Kang L.; Device Research Laboratory, Ucla Team; Kacst/California Institute Of Excellence On Green Nanotechnology Team

    2011-03-01

    A hybrid plasmonic nanostructure of an optically sensitive heterojunction organic film incorporating metal nanoparticles is fabricated. From the Charge Extraction in Linearly Increasing Voltage (CELIV) measurements, the mobility of this hybrid plasmonic nanostructure has been experimentally extracted to be at least one order of the magnitude higher than that of the organic film without metal nanoparticles. The measured absorption spectrum also shows the increasing of the intensity by around 28% as well as the broadening of the spectrum. The theoretical calculation confirms this broadband optical absorption enhancement results from localized surface plasmon resonance. The optimization of the density of the metal nanoparticles has been done to achieve the best performance for the photovoltaic devices. This work is supported in part by KACST/California Institute of Excellence on Green Nanotechnology.

  18. Metal-organic frameworks: Shuttling in the solid state

    NASA Astrophysics Data System (ADS)

    Olson, Mark A.

    2015-06-01

    Incorporating mechanically interlocked molecular shuttles within a metal-organic framework that has enough free space in the crystal lattice to permit volume-conserving translational motion sets the stage for defect-free molecular-electronic device fabrication and more.

  19. SEQUESTERING AGENTS FOR ACTIVE CAPS - REMEDIATION OF METALS AND ORGANICS

    SciTech Connect

    Knox, A; Michael Paller, M; Danny D. Reible, D; Xingmao Ma, X; Ioana G. Petrisor, I

    2007-05-10

    This research evaluated organoclays, zeolites, phosphates, and a biopolymer as sequestering agents for inorganic and organic contaminants. Batch experiments were conducted to identify amendments and mixtures of amendments for metal and organic contaminants removal and retention. Contaminant removal was evaluated by calculating partitioning coefficients. Metal retention was evaluated by desorption studies in which residue from the removal studies was extracted with 1 M MgCl{sub 2} solution. The results indicated that phosphate amendments, some organoclays, and the biopolymer, chitosan, were very effective sequestering agents for metals in fresh and salt water. Organoclays were very effective sorbents for phenanthrene, pyrene, and benzo(a)pyrene. Partitioning coefficients for the organoclays were 3000-3500 ml g{sup -1} for benzo(a)pyrene, 400-450 ml g{sup -1} for pyrene, and 50-70 ml g{sup -1} for phenanthrene. Remediation of sites with a mixture of contaminants is more difficult than sites with a single contaminant because metals and organic contaminants have different fate and transport mechanisms in sediment and water. Mixtures of amendments (e.g., organoclay and rock phosphate) have high potential for remediating both organic and inorganic contaminants under a broad range of environmental conditions, and have promise as components in active caps for sediment remediation.

  20. Omar Yaghi on Chemistry and Metal Organic Frameworks

    ScienceCinema

    Omar Yaghi

    2016-07-12

    In this edited version of the hour long talk, Omar Yaghi, director of the Molecular Foundry, sat down in conversation with Jeff Miller, head of Public Affairs, on July 11th, 2012 to discuss his fascination with the hidden world of chemistry and his work on Metal Organic Frameworks.

  1. Omar Yaghi on Chemistry and Metal Organic Frameworks

    SciTech Connect

    Omar Yaghi

    2012-07-23

    In this edited version of the hour long talk, Omar Yaghi, director of the Molecular Foundry, sat down in conversation with Jeff Miller, head of Public Affairs, on July 11th, 2012 to discuss his fascination with the hidden world of chemistry and his work on Metal Organic Frameworks.

  2. Metal-enhanced fluorescence: effect of surface coating

    NASA Astrophysics Data System (ADS)

    Lismont, M.; François, A.; Dreesen, L.; Monro, T. M.

    2014-03-01

    Metal Enhanced Fluorescence (MEF), a phenomenon arising when a fluorophore is in closed proximity to a metallic structure such as metallic films or nanostructures, is seen as a way to increase the amount of reactive oxygen species produced by the irradiation of the protoporphyrin IX (PpIX), a photosensitizer commonly used in photodynamic therapy. Here, we show a study of the distance-dependent of MEF by applying multiple layers of polyelectrolyte (PE) on silver nanoparticles (AgNPs) to progressively increase the distance between AgNPs and PpIX, covalently bond to the last polyelectrolyte layer as well as exploring the use of AgNPs of different sizes ranging from 40 to 100 nm. Up to four fold increase of PpIX fluorescence was observed when this photosensitizing agent is bounded onto 100 nm sized Ag NPs. The effective corresponding distance between AgNPs and PpIX is three layers of PE.

  3. Method of making metal-doped organic foam products

    DOEpatents

    Rinde, James A.

    1981-01-01

    Organic foams having a low density and very small cell size and method for roducing same in either a metal-loaded or unloaded (nonmetal loaded) form are described. Metal-doped foams are produced by soaking a polymer gel in an aqueous solution of desired metal salt, soaking the gel successively in a solvent series of decreasing polarity to remove water from the gel and replace it with a solvent of lower polarity with each successive solvent in the series being miscible with the solvents on each side and being saturated with the desired metal salt, and removing the last of the solvents from the gel to produce the desired metal-doped foam having desired density cell size, and metal loading. The unloaded or metal-doped foams can be utilized in a variety of applications requiring low density, small cell size foam. For example, rubidium-doped foam made in accordance with the invention has utility in special applications, such as in x-ray lasers.

  4. Metal enhanced fluorescence of Ag-nanoshell dimer

    NASA Astrophysics Data System (ADS)

    Liaw, Jiunn-Woei; Chen, Huang-Chih; Chen, Bae-Renn; Kuo, Mao-Kuen

    2014-04-01

    The plasmon modes of Ag-nanoshell dimer on metal enhanced fluorescence (MEF) are studied theoretically. The amplified excitation rate of a dimer (two identical Ag nanoshells) illuminated by a plane wave for exciting a molecule located at the gap center is calculated. Subsequently, the apparent quantum yield of the emission of the excited molecule affected by the dimer is investigated. The multiple multipole method is used for the both simulations. Finally, the enhancement factor of the dimer on the overall photoluminescence of the molecule in terms of the two parameters is evaluated. Our results show that Ag-nanoshell dimer is a dual-band photoluminescence enhancer for MEF at the bonding dipole and quadrupole modes. The former is broadband, and the latter narrowband. Both bands depend on the gap size. Moreover, the average enhancement factor of Ag-nanoshell dimer for MEF with a Stokes shift is discussed.

  5. Designer metal-nanoantennae/dye complexes for maximum fluorescence enhancement

    NASA Astrophysics Data System (ADS)

    Meng, Xiang; Yang, Hao; Grote, Richard R.; Dadap, Jerry I.; Panoiu, Nicolae C.; Osgood, Richard M.

    2015-09-01

    We theoretically investigate the fluorescence enhancement of a representative set of dye-molecules excited by three classes of nanoantennae, using a fully vectorial three-dimensional finite-difference time-domain (3D FDTD) method. Through these 3D FDTD calculations, in conjunction with analytic guidance using temporal coupled-mode (TCM) theory, we develop a design procedure for antennae assemblies that allow achieving fluorescence enhancements of 200-900 over the emission intensity in the bare dye molecule. The enhancement from these commercially available fluorochrome conjugates, namely, CFTM568, CFTM660R and CFTM790 are fully investigated using spherical-dimer, elliptical-dimer, and bowtie nanoantennae. These results demonstrate a method for rationally designing arbitrary metallic nanoparticle/emitter assemblies prior to their synthesis and assembly to achieve optimum fluorescence enhancement.

  6. Application of Terahertz Field Enhancement Effect in Metal Microstructures

    NASA Astrophysics Data System (ADS)

    Nakajima, M.; Kurihara, T.; Tadokoro, Y.; Kang, B.; Takano, K.; Yamaguchi, K.; Watanabe, H.; Oto, K.; Suemoto, T.; Hangyo, M.

    2016-12-01

    Applications of high-field terahertz pulses are attractive in physics and terahertz technology. In this study, two applications related to high-intensity terahertz pulses are demonstrated. The field enhancement effect by subwavelength metallic microstructures is utilized for terahertz excitation measurement. The spin precession dynamics in magnetic materials was induced by a terahertz magnetic field. Spin precession was amplified by one order of magnitude in amplitude by the enhanced magnetic terahertz field in orthoferrite ErFeO3 with metal microstructures. The induced spin dynamics was analyzed and explained by LLG-LCR model. Moreover, a detection method for terahertz pulses was developed using a cholesteric liquid crystal at room temperature without any electronic devices. The beam profile of terahertz pulses was visualized and compared to other methods such as the knife edge method using pyroelectric detector and micro-bolometer array. The liquid crystal terahertz imager is very simple and has good applicability as a portable terahertz-sensing card.

  7. Carbon Nanotube Bonding Strength Enhancement Using Metal "Wicking" Process

    NASA Technical Reports Server (NTRS)

    Lamb, James L.; Dickie, Matthew R.; Kowalczyk, Robert S.; Liao, Anna; Bronikowski, Michael J.

    2012-01-01

    Carbon nanotubes grown from a surface typically have poor bonding strength at the interface. A process has been developed for adding a metal coat to the surface of carbon nano tubes (CNTs) through a wicking process, which could lead to an enhanced bonding strength at the interface. This process involves merging CNTs with indium as a bump-bonding enhancement. Classical capillary theory would not normally allow materials that do not wet carbon or graphite to be drawn into the spacings by capillary action because the contact angle is greater than 90 degrees. However, capillary action can be induced through JPL's ability to fabricate oriented CNT bundles to desired spacings, and through the use of deposition techniques and temperature to control the size and mobility of the liquid metal streams and associated reservoirs. A reflow and plasma cleaning process has also been developed and demonstrated to remove indium oxide, and to obtain smooth coatings on the CNT bundles.

  8. Plasmonic Enhancement of the Ellipsometric Measurement of Thin Metal Lines

    NASA Astrophysics Data System (ADS)

    O'Mullane, Samuel

    In semiconductor manufacturing, defect analysis and process control are extremely important for optimal device performance and yield enhancement. One in-line tool used for quick optical characterization is the ellipsometer. Because it is nondestructive and largely automated, ellipsometers have become key tools in this process. Scatterometry based optical critical dimension (OCD) analysis is the full optical modeling of ellipsometric measurements using regression-based structures. Specifically for metallic gratings, OCD has a couple of challenges. First, the sensitivity to changes in the width of the metal lines is decreasing for smaller widths. Second, the main scatterometry spectral simulation method (rigorous coupled wave analysis, RCWA) can produce wildly inaccurate results if convergence is not maintained. The research that will follow demonstrates full convergence using RCWA and finite element method (FEM) simulations for metal gratings of this sort. Additionally, the main focus will be on design improvements to these metal gratings to boost sensitivity to their widths. The foundation of this improvement is plasmonic activity, realized for the first time in copper interconnect test structures. Both surface plasmon and localized plasmon activity will be discussed and seen in simulation spectra. The largest sensitivity improvement is due to localized plasmons which depend significantly on all feature dimensions of the metal grating. Importantly, the new cross-grating test structure design has increasing sensitivity with decreasing width. The proposed enhancement to sensitivity for these small metal lines is demonstrated through agreement between RCWA and FEM simulations. Due to considerably different methods and formulation, these simulations would only agree for physically measurable phenomena and converged spectra for each method.

  9. Silver-copper alloy nanoparticles for metal enhanced luminescence

    NASA Astrophysics Data System (ADS)

    Chowdhury, Sanchari; Bhethanabotla, Venkat R.; Sen, Rajan

    2009-09-01

    Large metal enhanced luminescence was realized at the vicinity of easily fabricated Ag-Cu alloy nanoparticles upon tuning of their surface plasmon resonance spectra by changing only one experimental variable—the annealing temperature, for maximum spectral overlap with the emission and excitation spectra of the luminophores. We observed strong emission enhancement of luminophores (141.48±19.20 times for Alexa Fluor 488 and 23.91±12.37 times for Alexa Fluor 594) at the vicinity of these Ag-Cu nanoparticles, which is significantly larger than for pure Ag nanoparticles. We present theoretical calculations to provide insights into these experimental findings.

  10. Enhancing conductivity of metallic carbon nanotube networks by transition metal adsorption

    SciTech Connect

    Ketolainen, T. Havu, V.; Puska, M. J.

    2015-02-07

    The conductivity of carbon nanotube thin films is mainly determined by carbon nanotube junctions, the resistance of which can be reduced by several different methods. We investigate electronic transport through carbon nanotube junctions in a four-terminal configuration, where two metallic single-wall carbon nanotubes are linked by a group 6 transition metal atom. The transport calculations are based on the Green’s function method combined with the density-functional theory. The transition metal atom is found to enhance the transport through the junction near the Fermi level. However, the size of the nanotube affects the improvement in the conductivity. The enhancement is related to the hybridization of chromium and carbon atom orbitals, which is clearly reflected in the character of eigenstates near the Fermi level. The effects of chromium atoms and precursor molecules remaining adsorbed on the nanotubes outside the junctions are also examined.

  11. Solution-based metal enhanced fluorescence with gold and gold/silver core-shell nanorods

    NASA Astrophysics Data System (ADS)

    Ren, Zebin; Li, Xiaoyi; Guo, Jingxia; Wang, Ruibo; Wu, Yanni; Zhang, Mingdi; Li, Caixia; Han, Qingyan; Dong, Jun; Zheng, Hairong

    2015-12-01

    Metal enhanced fluorescence of Oxazine720 fluorophore with gold and gold/silver core-shell nanorods is investigated experimentally in aqueous solution system. Metallic nanorods are synthesized for providing proper localized surface plasmon resonance and necessary enhancement to the fluorophore molecule. The experimental observation shows that the fluorescence enhancement increases firstly and then decreases when the concentration of metallic nanorods increases, which is resulted by the competition between enhanced emission and inner-filtering effect. Further investigation with different amounts of metallic nanorods shows that the relationship between metal enhanced fluorescence and spectral correlation strongly depends on the concentration of metallic nanorods.

  12. Broadband enhanced transmission of acoustic waves through serrated metal gratings

    NASA Astrophysics Data System (ADS)

    Qi, Dong-Xiang; Fan, Ren-Hao; Deng, Yu-Qiang; Peng, Ru-Wen; Wang, Mu; Jiangnan University Collaboration

    In this talk, we present our studies on broadband properties of acoustic waves through metal gratings. We have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the acoustic transmission properties of metal gratings with or without serrated boundaries. The average transmission is obviously enhanced for serrated metal gratings within a wide frequency range, while the Fabry-Perot resonance is significantly suppressed. An effective medium hypothesis with varying acoustic impedance is proposed to analyze the mechanism, which was verified through comparison with finite-element simulation. The serrated boundary supplies gradient mass distribution and gradient normal acoustic impedance, which could efficiently reduce the boundary reflection. Further, by increasing the region of the serrated boundary, we present a broadband high-transmission grating for wide range of incident angle. Our results may have potential applications to broadband acoustic imaging, acoustic sensing and new acoustic devices. References: [1] Dong-Xiang Qi, Yu-Qiang Deng, Di-Hu Xu, Ren-Hao Fan, Ru-Wen Peng, Ze-Guo Chen, Ming-Hui Lu, X. R. Huang and Mu Wang, Appl. Phys. Lett. 106, 011906 (2015); [2] Dong-Xiang Qi, Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Ming-Hui Lu, Xu Ni, Qing Hu, and Mu Wang, Applied Physics Letters 101, 061912 (2012).

  13. Metal-organic framework templated inorganic sorbents for rapid and efficient extraction of heavy metals.

    PubMed

    Abney, C W; Gilhula, J C; Lu, K; Lin, W

    2014-12-17

    An innovative wet-treatment with Na2 S transforms two indium metal-organic frameworks (MOFs) into a series of porous inorganic sorbents. These MOF-templated materials display remarkable affinity for heavy metals with saturation occurring in less than 1 h. The saturation capacity for Hg(II) exceeds 2 g g(-1) , more than doubling the best thiol-functionalized sorbents in the literature.

  14. Ultrasound enhanced process for extracting metal species in supercritical fluids

    DOEpatents

    Wai, Chien M.; Enokida, Youichi

    2006-10-31

    Improved methods for the extraction or dissolution of metals, metalloids or their oxides, especially lanthanides, actinides, uranium or their oxides, into supercritical solvents containing an extractant are disclosed. The disclosed embodiments specifically include enhancing the extraction or dissolution efficiency with ultrasound. The present methods allow the direct, efficient dissolution of UO2 or other uranium oxides without generating any waste stream or by-products.

  15. Hydrogen molecule binding to unsaturated metal sites in metal-organic frameworks studied by neutron powder diffraction and inelastic neutron scattering

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Brown, Craig; Neumann, Dan; Dinca, Mircea; Long, Jeffrey; Peterson, Vanessa; Kepert, Cameron

    2007-03-01

    Metal organic framework (MOF) materials have shown considerable potential for hydrogen storage arising from very large surface areas. However, the low binding energy of hydrogen molecules limits its storage capability to very low temperatures (< 77 K), which is impractical for industrial applications. Using neutron powder diffraction (NPD), we have characterized the hydrogen adsorption sites in a selected series of MOF materials with exposed unsaturated metal ions. Direct binding between the unsaturated metal ions and hydrogen molecules is observed and responsible for the enhanced initial hydrogen adsorption enthalpy. The different metals centers in these MOFs show different binding strength and interaction distances between the hydrogen molecule and metal ions. The organic linker also affects the overall H2 binding strength. Inelastic neutron scattering spectra of H2 in these MOFs are also discussed.

  16. Microporous metal-organic frameworks for storage and separation of small hydrocarbons.

    PubMed

    He, Yabing; Zhou, Wei; Krishna, Rajamani; Chen, Banglin

    2012-12-18

    Hydrocarbons are very important energy resources and raw materials for some industrially important products and fine chemicals. There is a need for the discovery of better materials that offer enhanced capacities for safe storage of hydrocarbons. Furthermore, the development of improved separation technologies will lead to significant reduction in energy requirements and costs. In this feature article, we provide an overview of the current status of the emerging microporous metal-organic frameworks for the storage and separation of small hydrocarbons.

  17. Impregnated Metal-Organic Frameworks for the Removal of Toxic Industrial Chemicals

    DTIC Science & Technology

    2008-11-01

    on a nanotechnology approach to sorbent development for air purification applications. Metal-organic frameworks ( MOFs ) are a novel class of materials...that allow for specific functionalities to be designed directly into a porous framework. This report summarizes the evaluation of MOFs impregnated...with various chemicals for enhanced reactivity. Specifically, MOF -5 (IRMOF-l) was impregnated with citric acid, copper acetate, copper oxide, and

  18. Planar Heterojunction Perovskite Solar Cells Incorporating Metal-Organic Framework Nanocrystals.

    PubMed

    Chang, Ting-Hsiang; Kung, Chung-Wei; Chen, Hsin-Wei; Huang, Tzu-Yen; Kao, Sheng-Yuan; Lu, Hsin-Che; Lee, Min-Han; Boopathi, Karunakara Moorthy; Chu, Chih-Wei; Ho, Kuo-Chuan

    2015-11-25

    Zr-based porphyrin metal-organic framework (MOF-525) nanocrystals with a crystal size of about 140 nm are synthesized and incorporated into perovskite solar cells. The morphology and crystallinity of the perovskite thin film are enhanced since the micropores of MOF-525 allow the crystallization of perovskite to occur inside; this observation results in a higher cell efficiency of the obtained MOF/perovskite solar cell.

  19. A Green Strategy to Prepare Metal Oxide Superstructure from Metal-Organic Frameworks

    PubMed Central

    Song, Yonghai; Li, Xia; Wei, Changting; Fu, Jinying; Xu, Fugang; Tan, Hongliang; Tang, Juan; Wang, Li

    2015-01-01

    Metal or metal oxides with diverse superstructures have become one of the most promising functional materials in sensor, catalysis, energy conversion, etc. In this work, a novel metal-organic frameworks (MOFs)-directed method to prepare metal or metal oxide superstructure was proposed. In this strategy, nodes (metal ions) in MOFs as precursors to form ordered building blocks which are spatially separated by organic linkers were transformed into metal oxide micro/nanostructure by a green method. Two kinds of Cu-MOFs which could reciprocally transform by changing solvent were prepared as a model to test the method. Two kinds of novel CuO with three-dimensional (3D) urchin-like and 3D rods-like superstructures composed of nanoparticles, nanowires and nanosheets were both obtained by immersing the corresponding Cu-MOFs into a NaOH solution. Based on the as-formed CuO superstructures, a novel and sensitive nonenzymatic glucose sensor was developed. The small size, hierarchical superstructures and large surface area of the resulted CuO superstructures eventually contribute to good electrocatalytic activity of the prepared sensor towards the oxidation of glucose. The proposed method of hierarchical superstructures preparation is simple, efficient, cheap and easy to mass production, which is obviously superior to pyrolysis. It might open up a new way for hierarchical superstructures preparation. PMID:25669731

  20. Hydrogen storage in Pd nanocrystals covered with a metal-organic framework

    NASA Astrophysics Data System (ADS)

    Li, Guangqin; Kobayashi, Hirokazu; Taylor, Jared M.; Ikeda, Ryuichi; Kubota, Yoshiki; Kato, Kenichi; Takata, Masaki; Yamamoto, Tomokazu; Toh, Shoichi; Matsumura, Syo; Kitagawa, Hiroshi

    2014-08-01

    Hydrogen is an essential component in many industrial processes. As a result of the recent increase in the development of shale gas, steam reforming of shale gas has received considerable attention as a major source of H2, and the more efficient use of hydrogen is strongly demanded. Palladium is well known as a hydrogen-storage metal and an effective catalyst for reactions related to hydrogen in a variety of industrial processes. Here, we present remarkably enhanced capacity and speed of hydrogen storage in Pd nanocrystals covered with the metal-organic framework (MOF) HKUST-1 (copper(II) 1,3,5-benzenetricarboxylate). The Pd nanocrystals covered with the MOF have twice the storage capacity of the bare Pd nanocrystals. The significantly enhanced hydrogen storage capacity was confirmed by hydrogen pressure-composition isotherms and solid-state deuterium nuclear magnetic resonance measurements. The speed of hydrogen absorption in the Pd nanocrystals is also enhanced by the MOF coating.

  1. Hydrogen storage in Pd nanocrystals covered with a metal-organic framework.

    PubMed

    Li, Guangqin; Kobayashi, Hirokazu; Taylor, Jared M; Ikeda, Ryuichi; Kubota, Yoshiki; Kato, Kenichi; Takata, Masaki; Yamamoto, Tomokazu; Toh, Shoichi; Matsumura, Syo; Kitagawa, Hiroshi

    2014-08-01

    Hydrogen is an essential component in many industrial processes. As a result of the recent increase in the development of shale gas, steam reforming of shale gas has received considerable attention as a major source of H2, and the more efficient use of hydrogen is strongly demanded. Palladium is well known as a hydrogen-storage metal and an effective catalyst for reactions related to hydrogen in a variety of industrial processes. Here, we present remarkably enhanced capacity and speed of hydrogen storage in Pd nanocrystals covered with the metal-organic framework (MOF) HKUST-1 (copper(II) 1,3,5-benzenetricarboxylate). The Pd nanocrystals covered with the MOF have twice the storage capacity of the bare Pd nanocrystals. The significantly enhanced hydrogen storage capacity was confirmed by hydrogen pressure-composition isotherms and solid-state deuterium nuclear magnetic resonance measurements. The speed of hydrogen absorption in the Pd nanocrystals is also enhanced by the MOF coating.

  2. Development of environmentally-benign wood preservatives based on the combination of organic biocides with antioxidants and metal chelators.

    PubMed

    Schultz, Tor P; Nicholas, Darrel D

    2002-11-01

    Wood extractives can be envisaged to protect heartwood by at least three different mechanisms, i.e. fungicide, free radical scavengers/antioxidants and as metal chelators. In short-term laboratory decay tests using two different wood species and decay fungi, the combination of different organic fungicides with various antioxidants and/or metal chelators gave enhanced activity as compared to the organic biocide alone, with the best results usually obtained with all three compounds. Outdoor ground-contact stakes treated with a biocide and antioxidant combination and exposed for 30 months also gave enhanced protection against both decay fungi and termites. It was concluded that the combination of an organic biocide with metal chelating and/or antioxidant additives gives enhanced protection to wood against fungi as compared to the biocide alone and, consequently, it may be possible to develop environmentally-benign wood preservative systems based on this idea.

  3. Understanding Organic Film Behavior on Alloy and Metal Oxides

    PubMed Central

    Raman, Aparna; Quiñones, Rosalynn; Barriger, Lisa; Eastman, Rachel; Parsi, Arash

    2010-01-01

    Native oxide surfaces of stainless steel 316L and Nitinol alloys and their constituent metal oxides namely, nickel, chromium, molybdenum, manganese, iron and titanium were modified with long chain organic acids to better understand organic film formation. The adhesion and stability of films of octadecylphosphonic acid, octadecylhydroxamic acid, octadecylcarboxylic acid and octadecylsulfonic acid on these substrates was examined in this study. The films formed on these surfaces were analyzed by diffuse reflectance infrared Fourier transform spectroscopy, contact angle goniometry, atomic force microscopy and matrix assisted laser desorption ionization mass spectrometry. The effect of the acidity of the organic moiety and substrate composition on the film characteristics and stability is discussed. Interestingly, on the alloy surfaces, the presence of less reactive metal sites does not inhibit film formation. PMID:20039608

  4. Metal-Organic Frameworks to Metal/Metal Oxide Embedded Carbon Matrix: Synthesis, Characterization and Gas Sorption Properties.

    PubMed

    Chen, Jiun-Jen; Chen, Ya-Ting; Raja, Duraisamy Senthil; Kang, Yu-Hao; Tseng, Pen-Chang; Lin, Chia-Her

    2015-08-19

    Three isostructural metal-organic frameworks, (MOFs), [Fe(OH)(1,4-NDC)] (1), [Al(OH)(1,4-NDC)] (2), and [In(OH)(1,4-NDC)] (3) have been synthesized hydrothermally by using 1,4-naphthalene dicarboxylate (1,4-NDC) as a linker. The MOFs were characterized using various techniques and further used as precursor materials for the synthesis of metal/metal oxide nanoparticles inserted in a carbon matrix through a simple thermal conversion method. The newly synthesized carbon materials were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy analysis, powder X-ray diffraction and BET analysis. The results showed that the MOF-derived carbon composite materials maintained the morphology of the original MOF upon carbonization, and confirmed the insertion of metal/metal oxide particles in the carbon matrix.

  5. Enhancement stabilization of heavy metals (Zn, Pb, Cr and Cu) during vermifiltration of liquid-state sludge.

    PubMed

    Yang, Jian; Zhao, Chunhui; Xing, Meiyan; Lin, Yanan

    2013-10-01

    This paper illustrated the potential effect of earthworms on heavy metal stabilization after vermifiltration of liquid-state sludge. Significant enhancement of organics degradation in sludge caused an increase of heavy metal concentrations in VF effluent sludge. However, the analysis of heavy metal chemical speciation indicated earthworms made unstable fractions of heavy metals transformed into stable fractions. Further investigation using principal component analysis revealed that transformations of heavy metal fractions were mainly due to the changes in sludge physico-chemical properties of pH, soluble chemical oxygen demand and available phosphorus. The bioassay of earthworms indicated that only zinc was accumulated by earthworms because the unstable fraction was its main chemical speciation. Furthermore, risk analysis demonstrated that earthworm activities weakened heavy metal risk due to the formation of stable fractions although their total concentrations increased. These results indicated that earthworms in vermifilter had a positive role in stabilizing heavy metals in sewage sludge. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Performance enhancement of organic photovoltaic devices enabled by Au nanoarrows inducing surface plasmonic resonance effect.

    PubMed

    Li, Shujun; Li, Zhiqi; Zhang, Xinyuan; Zhang, Zhihui; Liu, Chunyu; Shen, Liang; Guo, Wenbin; Ruan, Shengping

    2016-09-21

    The surface plasmon resonance (SPR) effect of metal nanoparticles is widely employed in organic solar cells to enhance device performance. However, the light-harvesting improvement is highly dependent on the shape of the metal nanoparticles. In this study, the significantly enhanced performance upon incorporation of Au nanoarrows in solution-processed organic photovoltaic devices is demonstrated. Incorporating Au nanoarrows into the ZnO cathode buffer layer results in superior broadband optical absorption improvement and a power conversion efficiency of 7.82% is realized with a 27.3% enhancement compared with the control device. The experimental and theoretical results indicate that the introduction of Au nanoarrows not only increases optical trapping by the SPR effect but also facilitates exciton generation, dissociation, and charge transport inside the thin film device.

  7. Metallated porphyrin based porous organic polymers as efficient electrocatalysts

    NASA Astrophysics Data System (ADS)

    Lu, Guolong; Zhu, Youlong; Xu, Kongliang; Jin, Yinghua; Ren, Zhiyong Jason; Liu, Zhenning; Zhang, Wei

    2015-10-01

    Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both alkaline and acidic media. Pyrolysis of CoPOP at various temperatures (600 °C, 800 °C, and 1000 °C) yields the materials consisting of graphitic carbon layers and cobalt nanoparticles, which show greatly enhanced catalytic activity compared to the as-synthesized CoPOP. Among them, CoPOP-800/C pyrolyzed at 800 °C shows the highest specific surface area and ORR activity, displaying the most positive half-wave potential (0.825 V vs. RHE) and the largest limited diffusion current density (5.35 mA cm-2) in an alkaline medium, which are comparable to those of commercial Pt/C (20 wt%) (half-wave potential 0.829 V vs. RHE, limited diffusion current density 5.10 mA cm-2). RDE and RRDE experiments indicate that CoPOP-800/C directly reduces molecular oxygen to water through a 4-e- pathway in both alkaline and acidic media. More importantly, CoPOP-800/C exhibits excellent durability and methanol-tolerance under acidic and alkaline conditions, which surpass the Pt/C (20 wt%) system.Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both

  8. Energy transfer in monodisperse quantum dot solids in the presence of self-organized array of metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Sadeghi, S. M.; West, R. G.

    2013-03-01

    We examined the interdot energy transfer between monodisperse quantum dots under different degrees of plasmonic effects (plasmonic field enhancement and Forster energy transfer from quantum dots to metallic nanoparticles). For this we studied emission of CdSe/ZnS quantum dots deposited on substrates containing self-organized arrays of gold nanoislands with radially distributed sizes gradually reduced from the centers of the substrates to their sides. The results suggest how metallic nanoparticles can be used to enhance interdot energy transfer in monodisperse quantum dots and how this process can explain some of the spectral changes seen in the emission of quantum dots when they are close to the metallic nanoparticles.

  9. Effect of organic substituents on the adsorption of carbon dioxide on a metal-organic framework

    NASA Astrophysics Data System (ADS)

    Thu Ha, Nguyen Thi; Lefedova, O. V.; Ha, Nguyen Ngoc

    2017-01-01

    The adsorption of carbon dioxide on the MOF-5 metal-organic framework and modifications of it obtained by replacing the hydrogen atoms in the organic ligands with electron donor (-CH3,-OCH3) or electron acceptor groups (-CN,-NO2) is investigated using the grand canonical Monte Carlo (GCMC) method and density functional theory (DFT). It is shown that the adsorption of carbon dioxide molecules on the structures of metal-organic frameworks is most likely on Zn4O clusters, and that the adsorption of carbon dioxide is of a physical nature. The presence of substituents-CH3,-OCH3,-CN in metal-organic frameworks increases their capacity to adsorb carbon dioxide, while that of nitro groups (-NO2) has the opposite effect.

  10. Metallated porphyrin based porous organic polymers as efficient electrocatalysts.

    PubMed

    Lu, Guolong; Zhu, Youlong; Xu, Kongliang; Jin, Yinghua; Ren, Zhiyong Jason; Liu, Zhenning; Zhang, Wei

    2015-11-21

    Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(II) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ∼100% constant ORR current over 50,000 s in both alkaline and acidic media. Pyrolysis of CoPOP at various temperatures (600 °C, 800 °C, and 1000 °C) yields the materials consisting of graphitic carbon layers and cobalt nanoparticles, which show greatly enhanced catalytic activity compared to the as-synthesized CoPOP. Among them, CoPOP-800/C pyrolyzed at 800 °C shows the highest specific surface area and ORR activity, displaying the most positive half-wave potential (0.825 V vs. RHE) and the largest limited diffusion current density (5.35 mA cm(-2)) in an alkaline medium, which are comparable to those of commercial Pt/C (20 wt%) (half-wave potential 0.829 V vs. RHE, limited diffusion current density 5.10 mA cm(-2)). RDE and RRDE experiments indicate that CoPOP-800/C directly reduces molecular oxygen to water through a 4-e(-) pathway in both alkaline and acidic media. More importantly, CoPOP-800/C exhibits excellent durability and methanol-tolerance under acidic and alkaline conditions, which surpass the Pt/C (20 wt%) system.

  11. Self-organized metal nanowire arrays with tunable optical anisotropy

    SciTech Connect

    Toma, A.; Chiappe, D.; Massabo, D.; Boragno, C.; Buatier de Mongeot, F.

    2008-10-20

    Here we report on the development of an unconventional approach for the physical synthesis of laterally ordered self-organized arrays of metallic nanowires supported on nanostructured dielectric templates. The method, based on a combination of nanoscale patterning of the glass substrate by ion beam sputtering with shadow deposition of the metal nanoparticles, provides a viable alternative to time consuming serial nanopatterning approaches. Far-field optical characterization demonstrates that the nanowire arrays exhibit tunable anisotropic properties in the visible range due to the excitation of localized plasmon resonances.

  12. The tuning of metal enhanced fluorescence for sensing applications.

    PubMed

    Ganguly, Mainak; Mondal, Chanchal; Chowdhury, Joydeep; Pal, Jaya; Pal, Anjali; Pal, Tarasankar

    2014-01-21

    Stable coinage metal nanoparticles (NPs) have been synthesized individually in an aqueous alkaline solution from the corresponding metal salts as precursors using the condensation product (CP) of salicylaldehyde and triethylenetetramine as a reagent. Silver and gold NPs are obtained with and without light illumination but UV irradiation is essential for Cu(0)NP formation. During nanoparticle formation the CP is oxidized to OCP which eventually becomes a fluorophore and also a stabilizer for the in situ produced NPs. It has been observed that silver and gold particle formation kinetics is accelerated by UV exposure. Thus the ease of evolution of coinage metal NP formation relates to their nobility. The as prepared OCP solutions containing coinage metals exhibit a fluorescence contrast behaviour (fluorescence enhancement by Cu and Ag; quenching by AuNP) due to the match and mismatch of wave vectors. The electric field evident from the FDTD simulation abreast of the scattering cross section of the NPs governed from Mie theory as a consequence of surface plasmon coupled emission (SPCE), near field electromagnetic intensity enhancement and lightening rod effect concentrating the electric field around the fluorophore are responsible for the Cu and AgNPs stimulated fluorescence. Again, lossy surface waves are anticipated for efficient quenching by the AuNPs. The most unprecedented observation is 'Turn On' fluorescence which is reported here as a result of the substitution of Au(0) or Cu(0) by Ag(0). Finally, the preferential fluorescence enhancement helps the selective detection of Ag(i) and Cu(ii) well below the US Environmental Protection Agency (EPA) permissible level by tuning the experimental conditions.

  13. Enhancement of Thermal Conductance at Metal-Dielectric Interfaces Using Subnanometer Metal Adhesion Layers

    NASA Astrophysics Data System (ADS)

    Jeong, Minyoung; Freedman, Justin P.; Liang, Hongliang Joe; Chow, Cheng-Ming; Sokalski, Vincent M.; Bain, James A.; Malen, Jonathan A.

    2016-01-01

    We show that the use of subnanometer adhesion layers significantly enhances the thermal interface conductance at metal-dielectric interfaces. A metal-dielectric interface between Au and sapphire (Al2O3) is considered using Cu (low optical loss) and Cr (high optical loss) as adhesion layers. To enable high throughput measurements, each adhesion layer is deposited as a wedge such that a continuous range of thicknesses could be sampled. Our measurements of thermal interface conductance at the metal-Al2O3 interface made using frequency-domain thermoreflectance show that a 1-nm-thick adhesion layer of Cu or Cr is sufficient to enhance the thermal interface conductance by more than a factor of 2 or 4, respectively, relative to the pure Au/Al2O3 interface. The enhancement agrees with the diffuse-mismatch-model-based predictions of accumulated thermal conductance versus adhesion-layer thickness assuming that it contributes phonons with wavelengths less than its thickness, while those with longer wavelengths transmit directly from the Au.

  14. Metal-Organic and Organic TADF-Materials: Status, Challenges and Characterization.

    PubMed

    Bergmann, Larissa; Zink, Daniel M; Bräse, Stefan; Baumann, Thomas; Volz, Daniel

    2016-06-01

    This section covers both metal-organic and organic materials that feature thermally activated delayed fluorescence (TADF). Such materials are especially useful for organic light-emitting diodes (OLEDs), a technology that was introduced in commercial displays only recently. We compare both material classes to show commonalities and differences, highlighting current issues and challenges. Advanced spectroscopic techniques as valuable tools to develop solutions to those issues are introduced. Finally, we provide an outlook over the field and highlight future trends.

  15. Anisotropic metal nanoparticles for surface enhanced Raman scattering.

    PubMed

    Reguera, Javier; Langer, Judith; Jiménez de Aberasturi, Dorleta; Liz-Marzán, Luis M

    2017-07-03

    The optimization of the enhancement of Raman scattering by plasmonic effects is largely determined by the properties of the enhancing substrates. The main parameters behind this effect are related to the morphology of plasmonic nanoparticles and their relative distribution within the substrate. We focus this tutorial review on the effects of nanoparticle morphology, for the particular case of anisotropic metal nanoparticles. Anisotropy in silver and gold nanoparticles offers the possibility to tailor their plasmonic properties and intrinsic electromagnetic "hotspots". We describe the effect of varying particle size and shape on the SERS signal, focusing on the most common anisotropic morphologies used for SERS. Especial emphasis is made on existing comparative studies that shed light on the effect of nanoparticle anisotropy on their enhancement capabilities. We aim at providing a general perspective toward understanding the general key factors and highlighting the difficulty in quantitatively determining SERS performance.

  16. Metals as radio-enhancers in oncology: The industry perspective.

    PubMed

    Pottier, Agnés; Borghi, Elsa; Levy, Laurent

    2015-12-18

    Radio-enhancers, metal-based nanosized agents, could play a key role in oncology. They may unlock the potential of radiotherapy by enhancing the radiation dose deposit within tumors when the ionizing radiation source is 'on', while exhibiting chemically inert behavior in cellular and subcellular systems when the radiation beam is 'off'. Important decision points support the development of these new type of therapeutic agents originated from nanotechnology. Here, we discuss from an industry perspective, the interest of developing radio-enhancer agents to improve tumor control, the relevance of nanotechnology to achieve adequate therapeutic attributes, and present some considerations for their development in oncology. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. When hole extraction determines charge transfer across metal-organic-metal structure

    NASA Astrophysics Data System (ADS)

    Govor, L. V.; Reiter, G.; Parisi, J.

    2016-03-01

    We examined the charge transfer in metal-organic-metal structure, where the contact resistance of the extracting interface is larger than the resistance of the organic crystalline material and the resistance of the injecting interface. If direct tunneling (low voltage) and Fowler-Nordheim tunnelling (high voltage) across both interfaces take place, part of the injected holes remains located in the organic crystal because of the blocking action of the extracting interface, but not because of traps within the organic crystalline material (which was negligible). If Fowler-Nordheim tunneling across the injecting interface and direct tunneling across the extracting interface take place for high voltages, the latter leads to the deviation of the total current-voltage characteristic from the power law I∼ Vγ with γ>2 to Ohm's law with γ≃1.0 .

  18. Surfactant biocatalyst for remediation of recalcitrant organics and heavy metals

    DOEpatents

    Brigmon, Robin L.; Story, Sandra; Altman, Denis J.; Berry, Christopher J.

    2011-05-03

    Novel strains of isolated and purified bacteria have been identified which have the ability to degrade petroleum hydrocarbons including a variety of PAHs. Several isolates also exhibit the ability to produce a biosurfactant. The combination of the biosurfactant-producing ability along with the ability to degrade PAHs enhances the efficiency with which PAHs may be degraded. Additionally, the biosurfactant also provides an additional ability to bind heavy metal ions for removal from a soil or aquatic environment.

  19. Surfactant biocatalyst for remediation of recalcitrant organics and heavy metals

    DOEpatents

    Brigmon, Robin L [North Augusta, SC; Story, Sandra [Greenville, SC; Altman, Denis J [Evans, GA; Berry, Christopher J [Aiken, SC

    2011-03-15

    Novel strains of isolated and purified bacteria have been identified which have the ability to degrade petroleum hydrocarbons including a variety of PAHs. Several isolates also exhibit the ability to produce a biosurfactant. The combination of the biosurfactant-producing ability along with the ability to degrade PAHs enhances the efficiency with which PAHs may be degraded. Additionally, the biosurfactant also provides an additional ability to bind heavy metal ions for removal from a soil or aquatic environment.

  20. Surfactant biocatalyst for remediation of recalcitrant organics and heavy metals

    DOEpatents

    Brigmon, Robin L.; Story, Sandra; Altman, Denis; Berry, Christopher J.

    2009-01-06

    Novel strains of isolated and purified bacteria have been identified which have the ability to degrade petroleum hydrocarbons including a variety of PAHs. Several isolates also exhibit the ability to produce a biosurfactant. The combination of the biosurfactant-producing ability along with the ability to degrade PAHs enhances the efficiency with which PAHs may be degraded. Additionally, the biosurfactant also provides an additional ability to bind heavy metal ions for removal from a soil or aquatic environment.

  1. Surfactant biocatalyst for remediation of recalcitrant organics and heavy metals

    DOEpatents

    Brigmon, Robin L [North Augusta, SC; Story, Sandra [Greenville, SC; Altman,; Denis, J [Evans, GA; Berry, Christopher J [Aiken, SC

    2011-03-29

    Novel strains of isolated and purified bacteria have been identified which have the ability to degrade petroleum hydrocarbons including a variety of PAHs. Several isolates also exhibit the ability to produce a biosurfactant. The combination of the biosurfactant-producing ability along with the ability to degrade PAHs enhances the efficiency with which PAHs may be degraded. Additionally, the biosurfactant also provides an additional ability to bind heavy metal ions for removal from a soil or aquatic environment.

  2. Influence of dissimilatory metal reduction on fate of organic and metal contaminants in the subsurface

    USGS Publications Warehouse

    Lovely, Derek R.; Anderson, Robert T.

    2000-01-01

    Geobacter become dominant members of the microbial community when Fe(III)-reducing conditions develop as the result of organic contamination, or when Fe(III) reduction is artificially stimulated. These results suggest that further understanding of the ecophysiology of Geobacter species would aid in better prediction of the natural attenuation of organic contaminants under anaerobic conditions and in the design of strategies for the bioremediation of subsurface metal contamination.

  3. Charge transfer enhances two-photon absorption in transition metal porphyrins.

    PubMed

    Humphrey, Jonathan L; Kuciauskas, Darius

    2006-03-29

    Two-photon absorption processes were investigated in electropolymerized Fe(III), Mn(III), and Co(II) 5,10,15,20-tetrakis-(4-hydroxytetraphenyl)porphyrin films. Degenerate four wave mixing (DFWM) spectroscopy with 100 fs pulses in the near-IR spectral region was used. Metalloporphyrins with strong charge transfer (CT) transitions in the linear absorption spectra also show enhanced two-photon absorption. (Metalloporphyrin two-photon absorption cross section, delta, increases >10 times over that for the metal free porphyrin.) This effect was attributed to a two-photon induced charge transfer between the metal ion's d orbitals and the pi-system of the porphyrin. Correlation of one- and two-photon absorption properties of transition metal porphyrins suggests a new and simple approach to improve organic materials for photonic applications.

  4. Influence of dissimilatory metal reduction on fate of organic and metal contaminants in the subsurface

    NASA Astrophysics Data System (ADS)

    Lovley, Derek R.; Anderson, Robert T.

    Dissimilatory Fe(III)-reducing microorganisms have the ability to destroy organic contaminants under anaerobic conditions by oxidizing them to carbon dioxide. Some Fe(III)-reducing microorganisms can also reductively dechlorinate chlorinated contaminants. Fe(III)-reducing microorganisms can reduce a variety of contaminant metals and convert them from soluble forms to forms that are likely to be immobilized in the subsurface. Studies in petroleum-contaminated aquifers have demonstrated that Fe(III)-reducing microorganisms can be effective agents in removing aromatic hydrocarbons from groundwater under anaerobic conditions. Laboratory studies have demonstrated the potential for Fe(III)-reducing microorganisms to remove uranium from contaminated groundwaters. The activity of Fe(III)-reducing microorganisms can be stimulated in several ways to enhance organic contaminant oxidation and metal reduction. Molecular analyses in both field and laboratory studies have demonstrated that microorganisms of the genus Geobacter become dominant members of the microbial community when Fe(III)-reducing conditions develop as the result of organic contamination, or when Fe(III) reduction is artificially stimulated. These results suggest that further understanding of the ecophysiology of Geobacter species would aid in better prediction of the natural attenuation of organic contaminants under anaerobic conditions and in the design of strategies for the bioremediation of subsurface metal contamination. Des micro-organismes simulant la réduction du fer ont la capacité de détruire des polluants organiques dans des conditions anérobies en les oxydant en dioxyde de carbone. Certains micro-organismes réducteurs de fer peuvent aussi dé-chlorer par réduction des polluants chlorés. Des micro-organismes réducteurs de fer peuvent réduire tout un ensemble de métaux polluants et les faire passer de formes solubles à des formes qui sont susceptibles d'être immobilisées dans le milieu

  5. Hollow metal nanostructures for enhanced plasmonics (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Genç, Aziz; Patarroyo, Javier; Sancho-Parramon, Jordi; Duchamp, Martial; Gonzalez, Edgar; Bastus, Neus G.; Houben, Lothar; Dunin-Borkowski, Rafal; Puntes, Victor F.; Arbiol, Jordi

    2016-03-01

    Complex metal nanoparticles offer a great playground for plasmonic nanoengineering, where it is possible to cover plasmon resonances from ultraviolet to near infrared by modifying the morphologies from solid nanocubes to nanoframes, multiwalled hollow nanoboxes or even nanotubes with hybrid (alternating solid and hollow) structures. We experimentally show that structural modifications, i.e. void size and final morphology, are the dominant determinants for the final plasmonic properties, while compositional variations allow us to get a fine tuning. EELS mappings of localized surface plasmon resonances (LSPRs) reveal an enhanced plasmon field inside the voids of hollow AuAg nanostructures along with a more homogeneous distributions of the plasmon fields around the nanostructures. With the present methodology and the appropriate samples we are able to compare the effects of hybridization at the nanoscale in hollow nanostructures. Boundary element method (BEM) simulations also reveal the effects of structural nanoengineering on plasmonic properties of hollow metal nanostructures. Possibility of tuning the LSPR properties of hollow metal nanostructures in a wide range of energy by modifying the void size/shell thickness is shown by BEM simulations, which reveals that void size is the dominant factor for tuning the LSPRs. As a proof of concept for enhanced plasmonic properties, we show effective label free sensing of bovine serum albumin (BSA) with some of our hollow nanostructures. In addition, the different plasmonic modes observed have also been studied and mapped in 3D.

  6. Metalation of a Mesoporous Three-Dimensional Covalent Organic Framework.

    PubMed

    Baldwin, Luke A; Crowe, Jonathan W; Pyles, David A; McGrier, Psaras L

    2016-11-23

    Constructing metalated three-dimensional (3D) covalent organic frameworks is a challenging synthetic task. Herein, we report the synthesis and characterization of a highly porous (SABET = 5083 m(2) g(-1)) 3D COF with a record low density (0.13 g cm(-3)) containing π-electron conjugated dehydrobenzoannulene (DBA) units. Metalation of DBA-3D-COF 1 with Ni to produce Ni-DBA-3D-COF results in a minimal reduction in the surface area (SABET = 4763 m(2) g(-1)) of the material due to the incorporation of the metal within the cavity of the DBA units, and retention of crystallinity. Both 3D DBA-COFs also display great uptake capacities for ethane and ethylene gas.

  7. Metal-Organic Frameworks as Catalysts for Oxidation Reactions.

    PubMed

    Dhakshinamoorthy, Amarajothi; Asiri, Abdullah M; Garcia, Hermenegildo

    2016-06-06

    This Concept is aimed at describing the current state of the art in metal-organic frameworks (MOFs) as heterogeneous catalysts for liquid-phase oxidations, focusing on three important substrates, namely, alkenes, alkanes and alcohols. Emphases are on the nature of active sites that have been incorporated within MOFs and on future targets to be set in this area. Thus, selective alkene epoxidation with peroxides or oxygen catalyzed by constitutional metal nodes of MOFs as active sites are still to be developed. Moreover, no noble metal-free MOF has been reported to date that can act as a general catalyst for the aerobic oxidation of primary and secondary aliphatic alcohols. In contrast, in the case of alkanes, a target should be to tune the polarity of MOF internal pores to control the outcome of the autooxidation process, resulting in the selective formation of alcohol/ketone mixtures at high conversion.

  8. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    PubMed Central

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk

    2016-01-01

    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range. PMID:27255209

  9. Metal Nanoparticle-Decorated Two-Dimensional Molybdenum Sulfide for Plasmonic-Enhanced Polymer Photovoltaic Devices

    PubMed Central

    Chuang, Ming-Kai; Yang, Shun-Shing; Chen, Fang-Chung

    2015-01-01

    Atomically thin two-dimensional (2D) transition metal dichalcogenides have also attracted immense interest because they exhibit appealing electronic, optical and mechanical properties. In this work, we prepared gold nanoparticle-decorated molybdenum sulfide (AuNP@MoS2) through a simple spontaneous redox reaction. Transmission electron microscopy, UV-Vis spectroscopy, and Raman spectroscopy were used to characterize the properties of the AuNP@MoS2 nanomaterials. Then we employed such nanocomposites as the cathode buffer layers of organic photovoltaic devices (OPVs) to trigger surface plasmonic resonance, leading to noticeable enhancements in overall device efficiencies. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the effects of localized surface plasmonic resonance. Our results suggest that the metal nanoparticle-decorated two-dimensional materials appear to have great potential for use in high-performance OPVs. PMID:28793513

  10. Metal Nanoparticle-Decorated Two-Dimensional Molybdenum Sulfide for Plasmonic-Enhanced Polymer Photovoltaic Devices.

    PubMed

    Chuang, Ming-Kai; Yang, Shun-Shing; Chen, Fang-Chung

    2015-08-21

    Atomically thin two-dimensional (2D) transition metal dichalcogenides have also attracted immense interest because they exhibit appealing electronic, optical and mechanical properties. In this work, we prepared gold nanoparticle-decorated molybdenum sulfide (AuNP@MoS2) through a simple spontaneous redox reaction. Transmission electron microscopy, UV-Vis spectroscopy, and Raman spectroscopy were used to characterize the properties of the AuNP@MoS2 nanomaterials. Then we employed such nanocomposites as the cathode buffer layers of organic photovoltaic devices (OPVs) to trigger surface plasmonic resonance, leading to noticeable enhancements in overall device efficiencies. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the effects of localized surface plasmonic resonance. Our results suggest that the metal nanoparticle-decorated two-dimensional materials appear to have great potential for use in high-performance OPVs.

  11. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    NASA Astrophysics Data System (ADS)

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk

    2016-06-01

    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range.

  12. Nanoporous metal organic frameworks as hybrid polymer-metal composites for drug delivery and biomedical applications.

    PubMed

    Beg, Sarwar; Rahman, Mahfoozur; Jain, Atul; Saini, Sumant; Midoux, Patrick; Pichon, Chantal; Ahmad, Farhan Jalees; Akhter, Sohail

    2017-04-01

    Metal organic frameworks (MOFs), porous hybrid polymer-metal composites at the nanoscale, are recent innovations in the field of chemistry; they are novel polymeric materials with diverse biomedical applications. MOFs are nanoporous materials, consisting of metal ions linked together by organic bridging ligands. The unique physical and chemical characteristics of MOFs have attracted wider attention from the scientific community, exploring their utility in the field of material science, biology, nanotechnology and drug delivery. The practical feasibility of MOFs is possible owing to their abilities for biodegradability, excellent porosity, high loading capacity, ease of surface modification, among others. In this regard, this review provides an account of various types of MOFs, their physiochemical characteristics and use in diverse disciplines of biomedical sciences - with special emphasis on drug delivery and theranostics. Moreover, this review also highlights the stability and toxicity issues of MOFs, along with their market potential for biomedical applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Functionalising metal-organic frameworks with metal complexes: the role of structural dynamics

    SciTech Connect

    Platero-Prats, Ana E.; Bermejo Gomez, Antonio; Chapman, Karena W.; Martin-Matute, Belen; Zou, Xiaodong

    2015-01-01

    A series of iridium-functionalised UiO-67 metal-organic frameworks (MOFs) were synthesised under conditions that simulate kinetically- and thermodynamically-controlled regimes. The degree of functionalisation depends on the reaction time and relative acidity of the native- and metallo-linkers, and can be optimised by controlling the reaction time.

  14. Smart Metal-Organic Framework Coatings: Triggered Antibiofilm Compound Release.

    PubMed

    Claes, Birgit; Boudewijns, Tom; Muchez, Laurens; Hooyberghs, Geert; Van der Eycken, Erik V; Vanderleyden, Jozef; Steenackers, Hans P; De Vos, Dirk E

    2017-02-08

    Metal-organic frameworks (MOFs) have a large potential for delivery of active molecules. Here, a MOF coating is investigated as a smart host matrix for triggered release of antibiofilm compounds. In addition to a coating consisting of the regular Fe-terephthalate MIL-88B(Fe), a new hydrophobic MIL-88B(Fe) coating is synthesized in hydrothermal conditions using palmitic acid as a lattice terminating group. These porous materials are used as a host matrix for the antibiofilm compound 5-(4-chlorophenyl)-N-(2-isobutyl)-2-aminoimidazole, which has a specific biofilm-inhibiting effect at concentrations at which no activity against planktonic cells is detected. The stability of MIL-88B(Fe) in distilled water and tryptic soy broth medium is investigated, together with the ability of iron(III) chelators to serve as a trigger for controlled decomposition of MIL-88B(Fe) by metal complexation. Organic iron chelators are used to mimic the iron chelating function of siderophores, which are specific molecules excreted by biofilm-forming bacteria. Trisodium citrate is able to chelate metal ions from the junctions of the framework. By sequestration of these metal ions, the host matrix is partially degraded, resulting in an antibiofilm compound release. Finally, the antibiofilm properties against Salmonella Typhimurium are validated by monitoring biofilm growth on MOF layers either loaded or not with aminoimidazole. A strong proof-of-concept is shown for efficient inhibition of biofilm growth through triggered antibiofilm compound release.

  15. Tuning the topological states in metal-organic bilayers

    NASA Astrophysics Data System (ADS)

    de Lima, F. Crasto; Ferreira, Gerson J.; Miwa, R. H.

    2017-09-01

    We have investigated the energetic stability and the electronic properties of metal-organic topological insulator bilayers (BLs), (MC4S4)3BL , with M = Ni and Pt, using first-principles calculations and tight-binding model. Our findings show that (MC4S4)3BL is an appealing platform to perform electronic band structure engineering, based on the topologically protected chiral edge states. The energetic stability of the BLs is ruled by van der Waals interactions, the AA stacking being the energetically most stable one. The electronic band structure is characterized by a combination of bonding and antibonding kagome band sets, revealing that (NiC4S4)3BL presents a Z2-metallic phase, whereas (PtC4S4)3BL may present Z2-metallic phase or quantum spin Hall phase. Those nontrivial topological states were confirmed by the formation of chiral edge states in (MC4S4)3BL nanoribbons. We show that the localization of the edge states can be controlled with a normal external electric field, breaking the mirror symmetry. Hence, the sign of electric field selects in which layer each set of edge states are located. Such a control on the (layer) localization of the topological edge states brings us an additional and interesting degree of freedom to control the transport properties in layered metal-organic topological insulators.

  16. Hydrogen storage in microporous metal-organic frameworks.

    PubMed

    Rosi, Nathaniel L; Eckert, Juergen; Eddaoudi, Mohamed; Vodak, David T; Kim, Jaheon; O'Keeffe, Michael; Yaghi, Omar M

    2003-05-16

    Metal-organic framework-5 (MOF-5) of composition Zn4O(BDC)3 (BDC = 1,4-benzenedicarboxylate) with a cubic three-dimensional extended porous structure adsorbed hydrogen up to 4.5 weight percent (17.2 hydrogen molecules per formula unit) at 78 kelvin and 1.0 weight percent at room temperature and pressure of 20 bar. Inelastic neutron scattering spectroscopy of the rotational transitions of the adsorbed hydrogen molecules indicates the presence of two well-defined binding sites (termed I and II), which we associate with hydrogen binding to zinc and the BDC linker, respectively. Preliminary studies on topologically similar isoreticular metal-organic framework-6 and -8 (IRMOF-6 and -8) having cyclobutylbenzene and naphthalene linkers, respectively, gave approximately double and quadruple (2.0 weight percent) the uptake found for MOF-5 at room temperature and 10 bar.

  17. Hydrogen Storage in Microporous Metal-Organic Frameworks

    NASA Astrophysics Data System (ADS)

    Rosi, Nathaniel L.; Eckert, Juergen; Eddaoudi, Mohamed; Vodak, David T.; Kim, Jaheon; O'Keeffe, Michael; Yaghi, Omar M.

    2003-05-01

    Metal-organic framework-5 (MOF-5) of composition Zn4O(BDC)3 (BDC = 1,4-benzenedicarboxylate) with a cubic three-dimensional extended porous structure adsorbed hydrogen up to 4.5 weight percent (17.2 hydrogen molecules per formula unit) at 78 kelvin and 1.0 weight percent at room temperature and pressure of 20 bar. Inelastic neutron scattering spectroscopy of the rotational transitions of the adsorbed hydrogen molecules indicates the presence of two well-defined binding sites (termed I and II), which we associate with hydrogen binding to zinc and the BDC linker, respectively. Preliminary studies on topologically similar isoreticular metal-organic framework-6 and -8 (IRMOF-6 and -8) having cyclobutylbenzene and naphthalene linkers, respectively, gave approximately double and quadruple (2.0 weight percent) the uptake found for MOF-5 at room temperature and 10 bar.

  18. Recent progress in the synthesis of metal-organic frameworks.

    PubMed

    Sun, Yujia; Zhou, Hong-Cai

    2015-10-01

    Metal-organic frameworks (MOFs) have attracted considerable attention for various applications due to their tunable structure, porosity and functionality. In general, MOFs have been synthesized from isolated metal ions and organic linkers under hydrothermal or solvothermal conditions via one-spot reactions. The emerging precursor approach and kinetically tuned dimensional augmentation strategy add more diversity to this field. In addition, to speed up the crystallization process and create uniform crystals with reduced size, many alternative synthesis routes have been explored. Recent advances in microwave-assisted synthesis and electrochemical synthesis are presented in this review. In recent years, post-synthetic approaches have been shown to be powerful tools to synthesize MOFs with modified functionality, which cannot be attained via de novo synthesis. In this review, some current accomplishments of post-synthetic modification (PSM) based on covalent transformations and coordinative interactions as well as post-synthetic exchange (PSE) in robust MOFs are provided.

  19. An Ising model for metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Höft, Nicolas; Horbach, Jürgen; Martín-Mayor, Victor; Seoane, Beatriz

    2017-08-01

    We present a three-dimensional Ising model where lines of equal spins are frozen such that they form an ordered framework structure. The frame spins impose an external field on the rest of the spins (active spins). We demonstrate that this "porous Ising model" can be seen as a minimal model for condensation transitions of gas molecules in metal-organic frameworks. Using Monte Carlo simulation techniques, we compare the phase behavior of a porous Ising model with that of a particle-based model for the condensation of methane (CH4) in the isoreticular metal-organic framework IRMOF-16. For both models, we find a line of first-order phase transitions that end in a critical point. We show that the critical behavior in both cases belongs to the 3D Ising universality class, in contrast to other phase transitions in confinement such as capillary condensation.

  20. Angstrom-Resolved Metal-Organic Framework-Liquid Interfaces.

    PubMed

    Chiodini, Stefano; Reinares-Fisac, Daniel; Espinosa, Francisco M; Gutiérrez-Puebla, Enrique; Monge, Angeles; Gándara, Felipe; Garcia, Ricardo

    2017-09-11

    Metal-organic frameworks (MOFs) are a class of crystalline materials with a variety of applications in gas storage, catalysis, drug delivery or light harvesting. The optimization of those applications requires the characterization of MOF structure in the relevant environment. Dynamic force microscopy has been applied to follow dynamic processes of metal-organic-framework material. We provide images with spatial and time resolutions, respectively, of angstrom and seconds that show that Ce-RPF-8 surfaces immersed in water and glycerol experience a surface reconstruction process that is characterized by the diffusion of the molecular species along the step edges of the open terraces. The rate of the surface reconstruction process depends on the liquid. In water it happens spontaneously while in glycerol is triggered by applying an external force.

  1. Recent progress in the synthesis of metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Sun, Yujia; Zhou, Hong-Cai

    2015-10-01

    Metal-organic frameworks (MOFs) have attracted considerable attention for various applications due to their tunable structure, porosity and functionality. In general, MOFs have been synthesized from isolated metal ions and organic linkers under hydrothermal or solvothermal conditions via one-spot reactions. The emerging precursor approach and kinetically tuned dimensional augmentation strategy add more diversity to this field. In addition, to speed up the crystallization process and create uniform crystals with reduced size, many alternative synthesis routes have been explored. Recent advances in microwave-assisted synthesis and electrochemical synthesis are presented in this review. In recent years, post-synthetic approaches have been shown to be powerful tools to synthesize MOFs with modified functionality, which cannot be attained via de novo synthesis. In this review, some current accomplishments of post-synthetic modification (PSM) based on covalent transformations and coordinative interactions as well as post-synthetic exchange (PSE) in robust MOFs are provided.

  2. Impact of metal and anion substitutions on the hydrogen storage properties of M-BTT metal-organic frameworks.

    PubMed

    Sumida, Kenji; Stück, David; Mino, Lorenzo; Chai, Jeng-Da; Bloch, Eric D; Zavorotynska, Olena; Murray, Leslie J; Dincă, Mircea; Chavan, Sachin; Bordiga, Silvia; Head-Gordon, Martin; Long, Jeffrey R

    2013-01-23

    Microporous metal-organic frameworks are a class of materials being vigorously investigated for mobile hydrogen storage applications. For high-pressure storage at ambient temperatures, the M(3)[(M(4)Cl)(3)(BTT)(8)](2) (M-BTT; BTT(3-) = 1,3,5-benzenetristetrazolate) series of frameworks are of particular interest due to the high density of exposed metal cation sites on the pore surface. These sites give enhanced zero-coverage isosteric heats of adsorption (Q(st)) approaching the optimal value for ambient storage applications. However, the Q(st) parameter provides only a limited insight into the thermodynamics of the individual adsorption sites, the tuning of which is paramount for optimizing the storage performance. Here, we begin by performing variable-temperature infrared spectroscopy studies of Mn-, Fe-, and Cu-BTT, allowing the thermodynamics of H(2) adsorption to be probed experimentally. This is complemented by a detailed DFT study, in which molecular fragments representing the metal clusters within the extended solid are simulated to obtain a more thorough description of the structural and thermodynamic aspects of H(2) adsorption at the strongest binding sites. Then, the effect of substitutions at the metal cluster (metal ion and anion within the tetranuclear cluster) is discussed, showing that the configuration of this unit indeed plays an important role in determining the affinity of the framework toward H(2). Interestingly, the theoretical study has identified that the Zn-based analogs would be expected to facilitate enhanced adsorption profiles over the compounds synthesized experimentally, highlighting the importance of a combined experimental and theoretical approach to the design and synthesis of new frameworks for H(2) storage applications.

  3. Capture of organic iodides from nuclear waste by metal-organic framework-based molecular traps.

    PubMed

    Li, Baiyan; Dong, Xinglong; Wang, Hao; Ma, Dingxuan; Tan, Kui; Jensen, Stephanie; Deibert, Benjamin J; Butler, Joseph; Cure, Jeremy; Shi, Zhan; Thonhauser, Timo; Chabal, Yves J; Han, Yu; Li, Jing

    2017-09-07

    Effective capture of radioactive organic iodides from nuclear waste remains a significant challenge due to the drawbacks of current adsorbents such as low uptake capacity, high cost, and non-recyclability. We report here a general approach to overcome this challenge by creating radioactive organic iodide molecular traps through functionalization of metal-organic framework materials with tertiary amine-binding sites. The molecular trap exhibits a high CH3I saturation uptake capacity of 71 wt% at 150 °C, which is more than 340% higher than the industrial adsorbent Ag(0)@MOR under identical conditions. These functionalized metal-organic frameworks also serve as good adsorbents at low temperatures. Furthermore, the resulting adsorbent can be recycled multiple times without loss of capacity, making recyclability a reality. In combination with its chemical and thermal stability, high capture efficiency and low cost, the adsorbent demonstrates promise for industrial radioactive organic iodides capture from nuclear waste. The capture mechanism was investigated by experimental and theoretical methods.Capturing radioactive organic iodides from nuclear waste is important for safe nuclear energy usage, but remains a significant challenge. Here, Li and co-workers fabricate a stable metal-organic framework functionalized with tertiary amine groups that exhibits high capacities for radioactive organic iodides uptake.

  4. Geometrically enhanced extraordinary magnetoresistance in semiconductor-metal hybrids

    NASA Astrophysics Data System (ADS)

    Hewett, T. H.; Kusmartsev, F. V.

    2010-12-01

    Extraordinary magnetoresistance (EMR) arises in hybrid systems consisting of semiconducting material with an embedded metallic inclusion. We have investigated such systems with the use of finite-element modeling, with our results showing good agreement to existing experimental data. We show that this effect can be dramatically enhanced by over four orders of magnitude as a result of altering the geometry of the conducting region. The significance of this result lies in its potential application to EMR magnetic field sensors utilizing more familiar semiconducting materials with nonoptimum material parameters, such as silicon. Our model has been extended further with a geometry based on the microstructure of the silver chalcogenides, consisting of a randomly sized and positioned metallic network with interspersed droplets. This model has shown a large and quasilinear magnetoresistance analogous to experimental findings.

  5. The evolution of galaxies. III - Metal-enhanced star formation

    NASA Technical Reports Server (NTRS)

    Talbot, R. J., Jr.; Arnett, W. D.

    1973-01-01

    The problem of the paucity of low-metal-abundance low-mass stars is discussed. One alternative to the variable-initial-mass-function (VIMF) solution is proposed. It is shown that this solution - metal-enhanced star formation - satisfies the classical test which prompted the VIMF hypothesis. Furthermore, with no additional parameters it provides improved fits to other tests - e.g., inhomogeneities in the abundances in young stars, concordance of all nucleo-cosmochronologies, and a required yield of heavy-element production which is consistent with current stellar evolution theory. In this model the age of the Galaxy is 18.6 plus or minus 5.7 b.y.

  6. The evolution of galaxies. III - Metal-enhanced star formation

    NASA Technical Reports Server (NTRS)

    Talbot, R. J., Jr.; Arnett, W. D.

    1973-01-01

    The problem of the paucity of low-metal-abundance low-mass stars is discussed. One alternative to the variable-initial-mass-function (VIMF) solution is proposed. It is shown that this solution - metal-enhanced star formation - satisfies the classical test which prompted the VIMF hypothesis. Furthermore, with no additional parameters it provides improved fits to other tests - e.g., inhomogeneities in the abundances in young stars, concordance of all nucleo-cosmochronologies, and a required yield of heavy-element production which is consistent with current stellar evolution theory. In this model the age of the Galaxy is 18.6 plus or minus 5.7 b.y.

  7. Metal/Semiconductor hybrid nanostructures for plasmon-enhanced applications.

    PubMed

    Jiang, Ruibin; Li, Benxia; Fang, Caihong; Wang, Jianfang

    2014-08-20

    Hybrid nanostructures composed of semiconductor and plasmonic metal components are receiving extensive attention. They display extraordinary optical characteristics that are derived from the simultaneous existence and close conjunction of localized surface plasmon resonance and semiconduction, as well as the synergistic interactions between the two components. They have been widely studied for photocatalysis, plasmon-enhanced spectroscopy, biotechnology, and solar cells. In this review, the developments in the field of (plasmonic metal)/semiconductor hybrid nanostructures are comprehensively described. The preparation of the hybrid nanostructures is first presented according to the semiconductor type, as well as the nanostructure morphology. The plasmonic properties and the enabled applications of the hybrid nanostructures are then elucidated. Lastly, possible future research in this burgeoning field is discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Fatigue-Resistance Enhancements by Glass-Forming Metallic Films

    SciTech Connect

    Liu, F. X.; Liaw, Peter K; Jiang, W. H.; Chiang, C L; Gao, Yanfei; Guan, Y F; Chu, J. P.; Rack, P. D.

    2007-01-01

    Zr-based glass-forming metallic films were coated on a 316L stainless steel and a Ni-based alloy by the magnetron-sputter deposition. Four-point-bending fatigue tests were conducted on those coated materials with the film surface on the tensile side. Results showed that the fatigue life and fatigue-endurance limit of the materials could be considerably improved, and the enhancements vary with the maximum applied stress and the substrate material. Fractographs showed that the film remained well adhered to the substrate even after the severe plastic deformation. Surface-roughness measurements indicated the improvement of the surface finishes due to the deposition of the glass-forming film. Nanoindentation test results suggested that the thin film exhibited both high yield strength and good ductility. The reduction of the surface roughness, good adhesion between the film and the substrate, and the excellent strength and ductility of the glass-forming metallic film are the major factors for the fatigue-resistance enhancements of the coated material. A micromechanical model is developed to illustrate the mechanisms of fatigue-resistance enhancements through the interaction between the amorphous film and the substrate slip bands.

  9. Polyoxometalate Cluster-Incorporated Metal-Organic Framework Hierarchical Nanotubes.

    PubMed

    Xu, Xiaobin; Chen, Shuangming; Chen, Yifeng; Sun, Hongyu; Song, Li; He, Wei; Wang, Xun

    2016-06-01

    A simple method to prepare metal-organic framework (MOF) nanotubes is developed by employing polyoxometalates (POMs) as modulators. The local structure of the MOF nanotubes is investigated combining XANES and EXAFS studies. These nanotubes show both an excellent catalytic performance in the detoxification of sulfur compounds in O2 atmosphere and a remarkable cycling stability as the anode material for lithium-ion batteries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A multistimuli-responsive photochromic metal-organic gel.

    PubMed

    Wei, Shi-Chao; Pan, Mei; Li, Kang; Wang, Sujuan; Zhang, Jianyong; Su, Cheng-Yong

    2014-04-02

    A photochromic metal-organic gel with thermo-, photo-, and anion-responsive behavior is obtained. Unusually, heating of the Al-ligand solution leads to gel formation and cooling to room temperature reverses the process to reform the solution. The gel is sensitive to weakly coordinating anions. Additionally, reversible photochromic transformations take place both in the solution and gel states, accompanied by reversibly switched luminescence.

  11. Metal-Organic Frameworks for Thin-Layer Chromatographic Applications.

    PubMed

    Schenk, Claudia; Kutzscher, Christel; Drache, Franziska; Helten, Stella; Senkovska, Irena; Kaskel, Stefan

    2017-01-25

    Preparation of thin-layer chromatographic (TLC) plates based on metal-organic frameworks (MOFs) as porous stationary phases is described. DUT-67 (DUT = Dresden University of Technology), a zirconium based MOF, was used in combination with a fluorescent indicator as stationary phase for analyzing a small selection of a wide spectrum of relevant analytes. The successful separation of benzaldehyde from trans-cinnamaldehyde and 4-aminophenol from 2-aminotoluene is reported as a model system using optimized eluent mixtures containing acetic acid.

  12. Nano-architecture of metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Milichko, Valentin A.; Zalogina, Anastasiia; Mingabudinova, Leila R.; Vinogradov, Alexander V.; Ubyivovk, Evgeniy; Krasilin, Andrei A.; Mukhin, Ivan; Zuev, Dmitry A.; Makarov, Sergey V.; Pidko, Evgeny A.

    2017-09-01

    Change the shape and size of materials supports new functionalities never found in the sources. This strategy has been recently applied for porous crystalline materials - metal-organic frameworks (MOFs) to create hollow nanoscale structures or mesostructures with improved functional properties. However, such structures are characterized by amorphous state or polycrystallinity which limits their applicability. Here we follow this strategy to create such nano- and mesostructures with perfect crystallinity and new photonics functionalities by laser or focused ion beam fabrication.

  13. Metal organic framework MIL-101 for radioiodine capture and storage

    NASA Astrophysics Data System (ADS)

    Assaad, Thaer; Assfour, Bassem

    2017-09-01

    we report on the use of metal organic frameworks(MOFs) for radioiodine recovery and storage. One MOF (namely MIL-101) was prepared and investigated in detail to demonstrate the iodine removal efficiency and capacity of MOFs. The typical sorption kinetics and uptake isotherms were measured using radioactive iodine (123 I) for the first time. Our measurements indicate that MOFs can capture and store radioiodine in very high efficiency and fast kinetics.

  14. Metal-organic frameworks for artificial photosynthesis and photocatalysis.

    PubMed

    Zhang, Teng; Lin, Wenbin

    2014-08-21

    Solar energy is an alternative, sustainable energy source for mankind. Finding a convenient way to convert sunlight energy into chemical energy is a key step towards realizing large-scale solar energy utilization. Owing to their structural regularity and synthetic tunability, metal-organic frameworks (MOFs) provide an interesting platform to hierarchically organize light-harvesting antennae and catalytic centers to achieve solar energy conversion. Such photo-driven catalytic processes not only play a critical role in the solar to chemical energy conversion scheme, but also provide a novel methodology for the synthesis of fine chemicals. In this review, we summarize the fundamental principles of energy transfer and photocatalysis and provide an overview of the latest progress in energy transfer, light-harvesting, photocatalytic proton and CO2 reduction, and water oxidation using MOFs. The applications of MOFs in organic photocatalysis and degradation of model organic pollutants are also discussed.

  15. Evolution of form in metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Lee, Jiyoung; Kwak, Ja Hun; Choe, Wonyoung

    2017-01-01

    Self-assembly has proven to be a widely successful synthetic strategy for functional materials, especially for metal-organic materials (MOMs), an emerging class of porous materials consisting of metal-organic frameworks (MOFs) and metal-organic polyhedra (MOPs). However, there are areas in MOM synthesis in which such self-assembly has not been fully utilized, such as controlling the interior of MOM crystals. Here we demonstrate sequential self-assembly strategy for synthesizing various forms of MOM crystals, including double-shell hollow MOMs, based on single-crystal to single-crystal transformation from MOP to MOF. Moreover, this synthetic strategy also yields other forms, such as solid, core-shell, double and triple matryoshka, and single-shell hollow MOMs, thereby exhibiting form evolution in MOMs. We anticipate that this synthetic approach might open up a new direction for the development of diverse forms in MOMs, with highly advanced areas such as sequential drug delivery/release and heterogeneous cascade catalysis targeted in the foreseeable future.

  16. Evaluating metal-organic frameworks for natural gas storage

    SciTech Connect

    Mason, JA; Veenstra, M; Long, JR

    2014-01-01

    Metal-organic frameworks have received significant attention as a new class of adsorbents for natural gas storage; however, inconsistencies in reporting high-pressure adsorption data and a lack of comparative studies have made it challenging to evaluate both new and existing materials. Here, we briefly discuss high-pressure adsorption measurements and review efforts to develop metal-organic frameworks with high methane storage capacities. To illustrate the most important properties for evaluating adsorbents for natural gas storage and for designing a next generation of improved materials, six metal-organic frameworks and an activated carbon, with a range of surface areas, pore structures, and surface chemistries representative of the most promising adsorbents for methane storage, are evaluated in detail. High-pressure methane adsorption isotherms are used to compare gravimetric and volumetric capacities, isosteric heats of adsorption, and usable storage capacities. Additionally, the relative importance of increasing volumetric capacity, rather than gravimetric capacity, for extending the driving range of natural gas vehicles is highlighted. Other important systems-level factors, such as thermal management, mechanical properties, and the effects of impurities, are also considered, and potential materials synthesis contributions to improving performance in a complete adsorbed natural gas system are discussed.

  17. Metal chelate fluorescence enhancement in micellar media and its applications to niobium and tantalum ultratrace determinations

    SciTech Connect

    Sanz-Medel, A.; Alonso, J.I.G.; Gonzalez, E.B.

    1985-07-01

    The fluorescence intensities of niobium and tantalum complexes with several fluorimetric organic reagents enhanced by micellar solutions have been examined. Flavone derivatives (morin and quercetin) produced the more intense fluorescing reactions in a cationic micellar medium and are studied in detail. Effects upon fluorescence of the nature of the tensoactive material used have been investigated. The charge of the micelle, presence of homomicelles in solution, and chemical structure of the cationic surfactant and lumophoric reagent proved to be the decisive factors which influence enhancement of fluorescence of a metal chelate by a surfactant. The dramatic effects of the appropriate organizing medium and of sulfate ions on fluorescence of the Nb(V) and Ta(V) complexes with morin and quercetin are discussed in an effort to elucidate what trends may exist in the fluorescence enhancement of metal chelates by micelles. A general reaction mechanism, for those systems studied, is proposed. Analytical applications of such micelle-enhanced reactions to the fluorimetric determination of ultratraces of Nb(V) and Ta(V) are also shown. 24 references, 10 figures, 3 tables.

  18. Functionalization of plasmonic metamaterials utilizing metal-organic framework thin films

    NASA Astrophysics Data System (ADS)

    Jakšić, Zoran; Popović, Zora; Djerdj, Igor; Jaćimović, Željko K.; Radulović, Katarina

    2012-05-01

    We considered theoretically and experimentally a strategy to functionalize plasmonic metamaterials utilizing either a metal-organic framework (MOF) or inorganic-organic hybrids for application in adsorption-based gas sensing. MOFs are one-dimensional (1D), 2D or 3D crystalline compounds that simultaneously contain metal ions or ion clusters and organic moieties, forming thus porous networks ensuring an increased effective surface for adsorption. Metamaterials can enhance plasmonic sensor performance through metal-dielectric nanocompositing that simultaneously tailors the electromagnetic response and boosts adsorption of the targeted analyte through the use of nanopores. To perform functionalization, it is necessary to integrate one or several layers of MOF nanocrystals with the metamaterial scaffold. The simplest approach is to use dip or drop coating or the layer-by-layer technique. The scaffolds that we considered included freestanding, ultrathin membranes and sandwich structures with nanoaperture arrays. For this investigation, we used a non-aqueous sol-gel route to synthesize vanadium oxyanthracene carboxylate, a novel material with 1D crystal structure. Our results suggest that preferential concentration of analyte within the MOF pores may ensure improved adsorption and thus sensor sensitivity enhancement. Also, one may increase selectivity by introducing nanoparticle fillers or by utilizing other functionalizing materials such as catalysts or ligands.

  19. Early holocene trace metal enrichment in organic lake sediments, Baffin Island, Arctic Canada

    SciTech Connect

    Wolfe, A.P.; Haertling, J.W.

    1997-02-01

    Trace metals having accumulated in preindustrial ({sup 14}C dated) sediments from two small, acid-sensitive, arctic lakes show unexpected stratigraphic trends. Concentrations of Cu, Cr, Pb, Ni, and Zn have successive maxima in early to mid-Holocene sediments, of amplitudes comparable to lakes affected by loading from industrial atmospheric fallout. These profiles contrast sharply the concentrations of elements primarily associated with catchment erosion (Ti, V, Zr), and are attributed to the enhanced transport of organic-bound trace metals from the catchments to the lakes in the early Holocene. Paleoliminological conditions conferred effective sedimentary sinks for each of the enriched elements, although a certain degree of diagenetic mobilization is also observed. The study verifies that natural conditions may, under specific circumstances, produce sediment chemical signatures of potentially toxic metals that bear similarities to those reported from lakes adversely impacted by atmospheric pollution. 31 refs., 4 figs., 1 tab.

  20. Improving thermoelectric efficiency in organic-metal nanocomposites via extra-low thermal boundary conductance

    NASA Astrophysics Data System (ADS)

    Jin, Yansha; Nola, Sam; Pipe, Kevin P.; Shtein, Max

    2013-11-01

    In organic semiconductors, the Wiedemann-Franz law is often violated, potentially enabling independent control over electrical and thermal conductivities, as observed here with the organic-metal nanocomposites. This effect is attributed to the interface between metal particles and organic matrix materials impeding thermal transport. Thermal conductivity (kth) can be decoupled from electrical conductivity (σe) in the composite of an archetypal organic semiconductor (Copper Phthalocyanine, CuPc) and silver, with thermal boundary conductance as low as 13 MW/m2K at the interface. We show that kth decreases with volume fraction occupied by silver nanoparticles (xAg%) in the dilute limit, reaching a minimum value at a concentration xAg%(min)=18%, while σe exceeds that of the pure organic semiconductor. Further modeling indicates that ZT values of organic-inorganic nanocomposites can be potentially enhanced 10 fold around xf%(min), compared to ZT of the pure compounds. These findings suggest a novel pathway for the future design of organic thermoelectric materials.

  1. High-internal-phase emulsions stabilized by metal-organic frameworks and derivation of ultralight metal-organic aerogels

    PubMed Central

    Zhang, Bingxing; Zhang, Jianling; Liu, Chengcheng; Peng, Li; Sang, Xinxin; Han, Buxing; Ma, Xue; Luo, Tian; Tan, Xiuniang; Yang, Guanying

    2016-01-01

    To design high-internal-phase emulsion (HIPE) systems is of great interest from the viewpoints of both fundamental researches and practical applications. Here we demonstrate for the first time the utilization of metal-organic framework (MOF) for HIPE formation. By stirring the mixture of water, oil and MOF at room temperature, the HIPE stabilized by the assembly of MOF nanocrystals at oil-water interface could be formed. The MOF-stabilized HIPE provides a novel route to produce highly porous metal-organic aerogel (MOA) monolith. After removing the liquids from the MOF-stabilized HIPE, the ultralight MOA with density as low as 0.01 g·cm−3 was obtained. The HIPE approach for MOA formation has unique advantages and is versatile in producing different kinds of ultralight MOAs with tunable porosities and structures. PMID:26892258

  2. High-internal-phase emulsions stabilized by metal-organic frameworks and derivation of ultralight metal-organic aerogels

    NASA Astrophysics Data System (ADS)

    Zhang, Bingxing; Zhang, Jianling; Liu, Chengcheng; Peng, Li; Sang, Xinxin; Han, Buxing; Ma, Xue; Luo, Tian; Tan, Xiuniang; Yang, Guanying

    2016-02-01

    To design high-internal-phase emulsion (HIPE) systems is of great interest from the viewpoints of both fundamental researches and practical applications. Here we demonstrate for the first time the utilization of metal-organic framework (MOF) for HIPE formation. By stirring the mixture of water, oil and MOF at room temperature, the HIPE stabilized by the assembly of MOF nanocrystals at oil-water interface could be formed. The MOF-stabilized HIPE provides a novel route to produce highly porous metal-organic aerogel (MOA) monolith. After removing the liquids from the MOF-stabilized HIPE, the ultralight MOA with density as low as 0.01 g·cm-3 was obtained. The HIPE approach for MOA formation has unique advantages and is versatile in producing different kinds of ultralight MOAs with tunable porosities and structures.

  3. Metal isotope coded profiling of organic ligands by mass spectrometry in aquatic environments

    NASA Astrophysics Data System (ADS)

    Wichard, Thomas; Deicke, Michael; Frieder Mohr, Jan; Klein, Martin

    2017-04-01

    Metal isotope coded profiling (MICP) introduces a universal discovery platform for metal chelating natural products that act as metallophores, ion buffers or sequestering agents. The detection of cation and oxoanion complexing ligands is facilitated by the identification of unique isotopic signatures created by the application of isotopically pure metals. We present a targeted analysis of low-molecular-weight organic ligands based on fast UHPLC-ESI-MS measurements. Replacement of, for example, natural iron or molybdenum with isotopically pure 54Fe/58Fe (ratio 1:1) or 95Mo/98Mo (ratio 1:1) causes easily detectable unique isotopic signatures in the mass spectra of potential metal-complexing ligands. This can be achieved under laboratory conditions not only in growth media, but also by spiking directly aqueous samples or solid-phase extracts. Importantly, as the relative affinity of the metallophores for e.g., Mo or Fe is dependent on the pH, all experiments needs to be conducted under pH-controlled conditions. The improved ionization efficiency of some metal complexes helps to enhance the signal-to-noise ratio compared to the free ligand at the same chromatographic conditions. The methodology does not necessarily depend on HR-ESI-MS measurements (e.g., Q-Exactive Orbitrap) and can be applied to any mass spectrometer. With MICP, two birds can be killed with one stone: (i) the identification of metallophores (e.g., siderophores, molybdophores) for metal uptake by any organism and (ii) organic ligands which solely work as metal buffer in dissolved organic matter (DOM). We currently address following two main research lines: First, DOM has often been used as a proxy for bio-productivity in terms of a carbon source; however, the specific impact of DOM as a "metal buffer" for biological processes is still under-investigated. Upon the administration of individual isotopes or isotopic pairs, for example, 54Fe/58Fe, 63Cu/65Cu, 66Zn/68Zn, or 95Mo/98Mo and subsequent

  4. Carborane-Based Metal-Organic Framework with High Methane and Hydrogen Storage Capacities

    DTIC Science & Technology

    2013-01-01

    REPORT Carborane-Based MetalOrganic Framework with High Methane and Hydrogen Storage Capacities 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: A Cu...Carborane-Based MetalOrganic Framework with High Methane and Hydrogen Storage Capacities Report Title ABSTRACT A Cu?carborane-based metal ?organic...Based MetalOrganic Framework with High Methane and Hydrogen Storage Capacities Robert D. Kennedy,† Vaiva Krungleviciute,‡,§ Daniel J. Clingerman,† Joseph

  5. Controlling the magnetism of adsorbed metal-organic molecules

    NASA Astrophysics Data System (ADS)

    Kuch, Wolfgang; Bernien, Matthias

    2017-01-01

    Gaining control on the size or the direction of the magnetic moment of adsorbed metal-organic molecules constitutes an important step towards the realization of a surface-mounted molecular spin electronics. Such control can be gained by taking advantage of interactions of the molecule’s magnetic moment with the environment. The paramagnetic moments of adsorbed metal-organic molecules, for example, can be controlled by the interaction with magnetically ordered substrates. Metalloporphyrins and -phthalocyanines display a quasi-planar geometry, allowing the central metal ion to interact with substrate electronic states. This can lead to magnetic coupling with a ferromagnetic or even antiferromagnetic substrate. The molecule-substrate coupling can be mediated and controlled by insertion layers such as oxygen atoms, graphene, or nonmagnetic metal layers. Control on the magnetic properties of adsorbed metalloporphyrins or -phthalocyanines can also be gained by on-surface chemical modification of the molecules. The magnetic moment or the magnetic coupling to ferromagnetic substrates can be changed by adsorption and thermal desorption of small molecules that interact with the fourfold-coordinated metal center via the remaining axial coordination site. Spin-crossover molecules, which possess a metastable spin state that can be switched by external stimuli such as temperature or light, are another promising class of candidates for control of magnetic properties. However, the immobilization of such molecules on a solid surface often results in a quench of the spin transition due to the interaction with the substrate. We present examples of Fe(II) spin-crossover complexes in direct contact with a solid surface that undergo a reversible spin-crossover transition as a function of temperature, by illumination with visible light, or can be switched by the tip of a scanning tunneling microscope.

  6. Controlling the magnetism of adsorbed metal-organic molecules.

    PubMed

    Kuch, Wolfgang; Bernien, Matthias

    2017-01-18

    Gaining control on the size or the direction of the magnetic moment of adsorbed metal-organic molecules constitutes an important step towards the realization of a surface-mounted molecular spin electronics. Such control can be gained by taking advantage of interactions of the molecule's magnetic moment with the environment. The paramagnetic moments of adsorbed metal-organic molecules, for example, can be controlled by the interaction with magnetically ordered substrates. Metalloporphyrins and -phthalocyanines display a quasi-planar geometry, allowing the central metal ion to interact with substrate electronic states. This can lead to magnetic coupling with a ferromagnetic or even antiferromagnetic substrate. The molecule-substrate coupling can be mediated and controlled by insertion layers such as oxygen atoms, graphene, or nonmagnetic metal layers. Control on the magnetic properties of adsorbed metalloporphyrins or -phthalocyanines can also be gained by on-surface chemical modification of the molecules. The magnetic moment or the magnetic coupling to ferromagnetic substrates can be changed by adsorption and thermal desorption of small molecules that interact with the fourfold-coordinated metal center via the remaining axial coordination site. Spin-crossover molecules, which possess a metastable spin state that can be switched by external stimuli such as temperature or light, are another promising class of candidates for control of magnetic properties. However, the immobilization of such molecules on a solid surface often results in a quench of the spin transition due to the interaction with the substrate. We present examples of Fe(II) spin-crossover complexes in direct contact with a solid surface that undergo a reversible spin-crossover transition as a function of temperature, by illumination with visible light, or can be switched by the tip of a scanning tunneling microscope.

  7. Enhanced Structural Organization in Covalent Organic Frameworks Through Fluorination.

    PubMed

    Alahakoon, Sampath B; McCandless, Gregory T; Karunathilake, Arosha A K; Thompson, Christina M; Smaldone, Ronald A

    2017-01-30

    Here, we report a structure-function study of imine covalent organic frameworks (COFs) comparing a series of novel fluorine-containing monomers to their non-fluorinated analogues. We found that the fluorine-containing monomers produced 2D-COFs with not only greatly improved surface areas (over 2000 m(2)  g(-1) compared to 760 m(2)  g(-1) for the non-fluorinated analogue), but also with improved crystallinity and larger, more defined pore diameters. We then studied the formation of these COFs under varying reaction times and temperatures to obtain a greater insight into their mechanism of formation.

  8. Understanding hydrogen adsorption in metal-organic frameworks with open metal sites: a computational study.

    PubMed

    Yang, Qingyuan; Zhong, Chongli

    2006-01-19

    Recent experimental investigations show that the open metal sites may have a favorable impact on the hydrogen adsorption capacity of metal-organic frameworks (MOFs); however, no definite evidence has been obtained to date and little is known on the interactions between hydrogen and the pore walls of this kind of MOFs. In this work, a combined grand canonical Monte Carlo simulation and density functional theory calculation is performed on the adsorption of hydrogen in MOF-505, a recently synthesized MOF with open metal sites, to provide insight into molecular-level details of the underlying mechanisms. This work shows that metal-oxygen clusters are preferential adsorption sites for hydrogen, and the strongest adsorption of hydrogen is found in the directions of coordinatively unsaturated open metal sites, providing evidence that the open metal sites have a favorable impact on the hydrogen sorption capacity of MOFs. The storage capacity of hydrogen of MOF-505 at room temperature and moderate pressures is predicted to be low, in agreement with the outcome for hydrogen physisorption in other porous materials.

  9. Nanoporous metal oxides with tunable and nanocrystalline frameworks via conversion of metal-organic frameworks.

    PubMed

    Kim, Tae Kyung; Lee, Kyung Joo; Cheon, Jae Yeong; Lee, Jae Hwa; Joo, Sang Hoon; Moon, Hoi Ri

    2013-06-19

    Nanoporous metal oxide materials are ubiquitous in the material sciences because of their numerous potential applications in various areas, including adsorption, catalysis, energy conversion and storage, optoelectronics, and drug delivery. While synthetic strategies for the preparation of siliceous nanoporous materials are well-established, nonsiliceous metal oxide-based nanoporous materials still present challenges. Herein, we report a novel synthetic strategy that exploits a metal-organic framework (MOF)-driven, self-templated route toward nanoporous metal oxides via thermolysis under inert atmosphere. In this approach, an aliphatic ligand-based MOF is thermally converted to nanoporous metal oxides with highly nanocrystalline frameworks, in which aliphatic ligands act as the self-templates that are afterward evaporated to generate nanopores. We demonstrate this concept with hierarchically nanoporous magnesia (MgO) and ceria (CeO2), which have potential applicability for adsorption, catalysis, and energy storage. The pore size of these nanoporous metal oxides can be readily tuned by simple control of experimental parameters. Significantly, nanoporous MgO exhibits exceptional CO2 adsorption capacity (9.2 wt %) under conditions mimicking flue gas. This MOF-driven strategy can be expanded to other nanoporous monometallic and multimetallic oxides with a multitude of potential applications.

  10. Reusable oxidation catalysis using metal-monocatecholato species in a robust metal-organic framework.

    PubMed

    Fei, Honghan; Shin, JaeWook; Meng, Ying Shirley; Adelhardt, Mario; Sutter, Jörg; Meyer, Karsten; Cohen, Seth M

    2014-04-02

    An isolated metal-monocatecholato moiety has been achieved in a highly robust metal-organic framework (MOF) by two fundamentally different postsynthetic strategies: postsynthetic deprotection (PSD) and postsynthetic exchange (PSE). Compared with PSD, PSE proved to be a more facile and efficient functionalization approach to access MOFs that could not be directly synthesized under solvothermal conditions. Metalation of the catechol functionality residing in the MOFs resulted in unprecedented Fe-monocatecholato and Cr-monocatecholato species, which were characterized by X-ray absorption spectroscopy, X-band electron paramagnetic resonance spectroscopy, and (57)Fe Mössbauer spectroscopy. The resulting materials are among the first examples of Zr(IV)-based UiO MOFs (UiO = University of Oslo) with coordinatively unsaturated active metal centers. Importantly, the Cr-metalated MOFs are active and efficient catalysts for the oxidation of alcohols to ketones using a wide range of substrates. Catalysis could be achieved with very low metal loadings (0.5-1 mol %). Unlike zeolite-supported, Cr-exchange oxidation catalysts, the MOF-based catalysts reported here are completely recyclable and reusable, which may make them attractive catalysts for 'green' chemistry processes.

  11. Metal-organic framework templated synthesis of ultrathin, well-aligned metallic nanowires.

    PubMed

    Volosskiy, Boris; Niwa, Kenta; Chen, Yu; Zhao, Zipeng; Weiss, Nathan O; Zhong, Xing; Ding, Mengning; Lee, Chain; Huang, Yu; Duan, Xiangfeng

    2015-03-24

    With well-defined porous structures and dimensions, metal-organic frameworks (MOFs) can function as versatile templates for the growth of metallic nanostructures with precisely controlled shapes and sizes. Using MOFs as templates, metallic nanostructures can be grown without the need of bulky surfactants and thus preserve their intrinsic surface. Additionally, the high surface area of MOFs can also ensure that the surface of the template metallic nanostructures is readily accessible, which is critical for the proper function of catalysts or sensors. The hybrid metal@MOF structures have been demonstrated to exhibit useful properties not found in either component separately. Here we report the growth of ultrafine metallic nanowires inside one-dimensional MOF pores with well-controlled shape and size. Our study shows that solvent selection plays an important role in controlling precursor loading and the reduction rate inside the MOF pores for the formation of the nanowires. The growth of the well-aligned, ultrathin nanowires was monitored and characterized by transmission electron microscopy, X-ray diffraction, UV-vis spectroscopy, fluorescence studies, and Brunauer-Emmet-Teller surface area analysis.

  12. Metal-organic frameworks: versatile heterogeneous catalysts for efficient catalytic organic transformations.

    PubMed

    Chughtai, Adeel H; Ahmad, Nazir; Younus, Hussein A; Laypkov, A; Verpoort, Francis

    2015-10-07

    Novel catalytic materials are highly demanded to perform a variety of catalytic organic reactions. MOFs combine the benefits of heterogeneous catalysis like easy post reaction separation, catalyst reusability, high stability and homogeneous catalysis such as high efficiency, selectivity, controllability and mild reaction conditions. The possible organization of active centers like metallic nodes, organic linkers, and their chemical synthetic functionalization on the nanoscale shows potential to build up MOFs particularly modified for catalytic challenges. In this review, we have summarized the recent research progress in heterogeneous catalysis by MOFs and their catalytic behavior in various organic reactions, highlighting the key features of MOFs as catalysts based on the active sites in the framework. Examples of their post functionalization, inclusion of active guest species and metal nanoparticles have been discussed. Finally, the use of MOFs as catalysts for asymmetric heterogeneous catalysis and stability of MOFs has been presented as separate sections.

  13. Fluorine in a Carbon-enhanced Metal-poor Star

    NASA Astrophysics Data System (ADS)

    Schuler, Simon C.; Cunha, Katia; Smith, Verne V.; Sivarani, Thirupathi; Beers, Timothy C.; Lee, Young Sun

    2007-09-01

    The fluorine abundance of the carbon-enhanced metal-poor (CEMP) star HE 1305+0132 has been derived by analysis of the molecular HF (1-0) R9 line at 2.3357 μm in a high-resolution (R=50,000) spectrum obtained with the Phoenix spectrometer and Gemini-South telescope. Our abundance analysis makes use of a CNO-enhanced ATLAS12 model atmosphere characterized by a metallicity and CNO enhancements determined utilizing medium-resolution (R=3000) optical and near-IR spectra. The effective iron abundance is found to be [Fe/H]=-2.5, making HE 1305+0132 the most Fe-deficient star, by more than an order of magnitude, for which the abundance of fluorine has been measured. Using spectral synthesis, we derive a supersolar fluorine abundance of A(19F)=4.96+/-0.21, corresponding to a relative abundance of [F/Fe]=+2.90. A single line of the Phillips C2 system is identified in our Phoenix spectrum, and along with multiple lines of the first-overtone vibration-rotation CO (3-1) band head, C and O abundances of A(12C)=8.57+/-0.11 and A(16O)=7.04+/-0.14 are derived. We consider the striking fluorine overabundance in the framework of the nucleosynthetic processes thought to be responsible for the C-enhancement of CEMP stars and conclude that the atmosphere of HE 1305+0132 was polluted via mass transfer by a primary companion during its asymptotic giant branch phase. This is the first study of fluorine in a CEMP star, and it demonstrates that this rare nuclide can be a key diagnostic of nucleosynthetic processes in the early Galaxy.

  14. Interplay between defects, disorder and flexibility in metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Bennett, Thomas D.; Cheetham, Anthony K.; Fuchs, Alain H.; Coudert, François-Xavier

    2017-01-01

    Metal-organic frameworks are a novel family of chemically diverse materials, which are of interest across engineering, physics, chemistry, biology and medicine-based disciplines. Since the development of the field in its current form more than two decades ago, priority has been placed on the synthesis of new structures. However, more recently, a clear trend has emerged in shifting the emphasis from material design to exploring the chemical and physical properties of structures already known. In particular, although such nanoporous materials were traditionally seen as rigid crystalline structures, there is growing evidence that large-scale flexibility, the presence of defects and long-range disorder are not the exception in metal-organic frameworks, but the rule. Here we offer some perspective into how these concepts are perhaps inescapably intertwined, highlight recent advances in our understanding and discuss how a consideration of the interfaces between them may lead to enhancements of the materials' functionalities.

  15. Selective sulfur dioxide adsorption on crystal defect sites on an isoreticular metal organic framework series

    PubMed Central

    Rodríguez-Albelo, L. Marleny; López-Maya, Elena; Hamad, Said; Ruiz-Salvador, A. Rabdel; Calero, Sofia; Navarro, Jorge A.R.

    2017-01-01

    The widespread emissions of toxic gases from fossil fuel combustion represent major welfare risks. Here we report the improvement of the selective sulfur dioxide capture from flue gas emissions of isoreticular nickel pyrazolate metal organic frameworks through the sequential introduction of missing-linker defects and extra-framework barium cations. The results and feasibility of the defect pore engineering carried out are quantified through a combination of dynamic adsorption experiments, X-ray diffraction, electron microscopy and density functional theory calculations. The increased sulfur dioxide adsorption capacities and energies as well as the sulfur dioxide/carbon dioxide partition coefficients values of defective materials compared to original non-defective ones are related to the missing linkers enhanced pore accessibility and to the specificity of sulfur dioxide interactions with crystal defect sites. The selective sulfur dioxide adsorption on defects indicates the potential of fine-tuning the functional properties of metal organic frameworks through the deliberate creation of defects. PMID:28198376

  16. Giant negative linear compression positively coupled to massive thermal expansion in a metal-organic framework.

    PubMed

    Cai, Weizhao; Katrusiak, Andrzej

    2014-07-04

    Materials with negative linear compressibility are sought for various technological applications. Such effects were reported mainly in framework materials. When heated, they typically contract in the same direction of negative linear compression. Here we show that this common inverse relationship rule does not apply to a three-dimensional metal-organic framework crystal, [Ag(ethylenediamine)]NO3. In this material, the direction of the largest intrinsic negative linear compression yet observed in metal-organic frameworks coincides with the strongest positive thermal expansion. In the perpendicular direction, the large linear negative thermal expansion and the strongest crystal compressibility are collinear. This seemingly irrational positive relationship of temperature and pressure effects is explained and the mechanism of coupling of compressibility with expansivity is presented. The positive coupling between compression and thermal expansion in this material enhances its piezo-mechanical response in adiabatic process, which may be used for designing new artificial composites and ultrasensitive measuring devices.

  17. Selective sulfur dioxide adsorption on crystal defect sites on an isoreticular metal organic framework series

    NASA Astrophysics Data System (ADS)

    Rodríguez-Albelo, L. Marleny; López-Maya, Elena; Hamad, Said; Ruiz-Salvador, A. Rabdel; Calero, Sofia; Navarro, Jorge A. R.

    2017-02-01

    The widespread emissions of toxic gases from fossil fuel combustion represent major welfare risks. Here we report the improvement of the selective sulfur dioxide capture from flue gas emissions of isoreticular nickel pyrazolate metal organic frameworks through the sequential introduction of missing-linker defects and extra-framework barium cations. The results and feasibility of the defect pore engineering carried out are quantified through a combination of dynamic adsorption experiments, X-ray diffraction, electron microscopy and density functional theory calculations. The increased sulfur dioxide adsorption capacities and energies as well as the sulfur dioxide/carbon dioxide partition coefficients values of defective materials compared to original non-defective ones are related to the missing linkers enhanced pore accessibility and to the specificity of sulfur dioxide interactions with crystal defect sites. The selective sulfur dioxide adsorption on defects indicates the potential of fine-tuning the functional properties of metal organic frameworks through the deliberate creation of defects.

  18. Selective sulfur dioxide adsorption on crystal defect sites on an isoreticular metal organic framework series.

    PubMed

    Rodríguez-Albelo, L Marleny; López-Maya, Elena; Hamad, Said; Ruiz-Salvador, A Rabdel; Calero, Sofia; Navarro, Jorge A R

    2017-02-15

    The widespread emissions of toxic gases from fossil fuel combustion represent major welfare risks. Here we report the improvement of the selective sulfur dioxide capture from flue gas emissions of isoreticular nickel pyrazolate metal organic frameworks through the sequential introduction of missing-linker defects and extra-framework barium cations. The results and feasibility of the defect pore engineering carried out are quantified through a combination of dynamic adsorption experiments, X-ray diffraction, electron microscopy and density functional theory calculations. The increased sulfur dioxide adsorption capacities and energies as well as the sulfur dioxide/carbon dioxide partition coefficients values of defective materials compared to original non-defective ones are related to the missing linkers enhanced pore accessibility and to the specificity of sulfur dioxide interactions with crystal defect sites. The selective sulfur dioxide adsorption on defects indicates the potential of fine-tuning the functional properties of metal organic frameworks through the deliberate creation of defects.

  19. Metal organic frameworks for the catalytic detoxification of chemical warfare nerve agents

    DOEpatents

    Hupp, Joseph T.; Farha, Omar K.; Katz, Michael J.; Mondloch, Joseph E.

    2017-04-18

    A method of using a metal organic framework (MOF) comprising a metal ion and an at least bidendate organic ligand to catalytically detoxify chemical warfare nerve agents including exposing the metal-organic-framework (MOF) to the chemical warfare nerve agent and catalytically decomposing the nerve agent with the MOF.

  20. Controlled Encapsulation of Functional Organic Molecules within Metal-Organic Frameworks: In Situ Crystalline Structure Transformation.

    PubMed

    Guan, Jinju; Hu, Yu; Wang, Yu; Li, Hongfeng; Xu, Zhiling; Zhang, Tao; Wu, Peng; Zhang, Suoying; Xiao, Gengwu; Ji, Wenlan; Li, Linjie; Zhang, Meixuan; Fan, Yun; Li, Lin; Zheng, Bing; Zhang, Weina; Huang, Wei; Huo, Fengwei

    2017-01-23

    Functional organic molecules/metal-organic frameworks composites can be obtained by in situ crystalline structure transformation from ZIF-L to ZIF-8-L under double solvent conditions. Interestingly, the as-prepared molecules/ZIF-8-L composites with the leaf-like morphology exhibit good fluorescence properties and size selectivity in fluorescent quenchers due to the molecular sieving effect of the well-defined microporous ZIF-8-L.

  1. LITHIUM ABUNDANCES IN CARBON-ENHANCED METAL-POOR STARS

    SciTech Connect

    Masseron, Thomas; Johnson, Jennifer A.; Lucatello, Sara; Karakas, Amanda; Plez, Bertrand; Beers, Timothy C.; Christlieb, Norbert E-mail: jaj@astronomy.ohio-state.edu

    2012-05-20

    Carbon-enhanced metal-poor (CEMP) stars are believed to show the chemical imprints of more massive stars (M {approx}> 0.8 M{sub Sun }) that are now extinct. In particular, it is expected that the observed abundance of Li should deviate in these stars from the standard Spite lithium plateau. We study here a sample of 11 metal-poor stars and a double-lined spectroscopic binary with -1.8 < [Fe/H] < -3.3 observed with the Very Large Telescope/UVES spectrograph. Among these 12 metal-poor stars, there are 8 CEMP stars for which we measure or constrain the Li abundance. In contrast to previous arguments, we demonstrate that an appropriate regime of dilution permits the existence of 'Li-Spite plateau and C-rich' stars, whereas some of the 'Li-depleted and C-rich' stars call for an unidentified additional depletion mechanism that cannot be explained by dilution alone. We find evidence that rotation is related to the Li depletion in some CEMP stars. Additionally, we report on a newly recognized double-lined spectroscopic binary star in our sample. For this star, we develop a new technique from which estimates of stellar parameters and luminosity ratios can be derived based on a high-resolution spectrum alone, without the need for input from evolutionary models.

  2. Refolding of horseradish peroxidase is enhanced in presence of metal cofactors and ionic liquids.

    PubMed

    Bae, Sang-Woo; Eom, Doyoung; Mai, Ngoc Lan; Koo, Yoon-Mo

    2016-03-01

    The effects of various refolding additives, including metal cofactors, organic co-solvents, and ionic liquids, on the refolding of horseradish peroxidase (HRP), a well-known hemoprotein containing four disulfide bonds and two different types of metal centers, a ferrous ion-containing heme group and two calcium atoms, which provide a stabilizing effect on protein structure and function, were investigated. Both metal cofactors (Ca(2+) and hemin) and ionic liquids have positive impact on the refolding of HRP. For instance, the HRP refolding yield remarkably increased by over 3-fold upon addition of hemin and calcium chloride to the refolding buffer as compared to that in the conventional urea-containing refolding buffer. Moreover, the addition of ionic liquids [EMIM][Cl] to the hemin and calcium cofactor-containing refolding buffer further enhanced the HRP refolding yield up to 80% as compared to 12% in conventional refolding buffer at relatively high initial protein concentration (5 mg/ml). These results indicated that refolding method utilizing metal cofactors and ionic liquids could enhance the yield and efficiency for metalloprotein.

  3. Noble metal-comparable SERS enhancement from semiconducting metal oxides by making oxygen vacancies

    NASA Astrophysics Data System (ADS)

    Cong, Shan; Yuan, Yinyin; Chen, Zhigang; Hou, Junyu; Yang, Mei; Su, Yanli; Zhang, Yongyi; Li, Liang; Li, Qingwen; Geng, Fengxia; Zhao, Zhigang

    2015-07-01

    Surface-enhanced Raman spectroscopy (SERS) represents a very powerful tool for the identification of molecular species, but unfortunately it has been essentially restricted to noble metal supports (Au, Ag and Cu). While the application of semiconductor materials as SERS substrate would enormously widen the range of uses for this technique, the detection sensitivity has been much inferior and the achievable SERS enhancement was rather limited, thereby greatly limiting the practical applications. Here we report the employment of non-stoichiometric tungsten oxide nanostructure, sea urchin-like W18O49 nanowire, as the substrate material, to magnify the substrate-analyte molecule interaction, leading to significant magnifications in Raman spectroscopic signature. The enrichment of surface oxygen vacancy could bring additional enhancements. The detection limit concentration was as low as 10-7 M and the maximum enhancement factor was 3.4 × 105, in the rank of the highest sensitivity, to our best knowledge, among semiconducting materials, even comparable to noble metals without `hot spots'.

  4. Metallic coatings for enhancement of thermal contact conductance

    NASA Astrophysics Data System (ADS)

    Lambert, M. A.; Fletcher, L. S.

    1994-04-01

    The reliability of standard electronic modules may be improved by decreasing overall module temperature. This may be accomplished by enhancing the thermal contact conductance at the interface between the module frame guide rib and the card rail to which the module is clamped. Some metallic coatings, when applied to the card rail, would deform under load, increasing the contact area and associated conductance. This investigation evaluates the enhancements in thermal conductance afforded by vapor deposited silver and gold coatings. Experimental thermal conductance measurements were made for anodized aluminum 6101-T6 and electroless nickel-plated copper C11000-H03 card materials to the aluminum A356-T61 rail material. Conductance values for the electroless nickel-plated copper junction ranged from 600 to 2800 W/m(exp 2)K and those for the anodized aluminum junction ranged from 25 to 91 W/m(exp 2)K for contact pressures of 0.172-0.862 MPa and mean junction temperatures of 20-100 C. Experimental thermal conductance values of vapor deposited silver- and gold-coated aluminum A356-T61 rail surfaces indicate thermal enhancements of 1.25-2.19 for the electroless nickel-plated copper junctions and 1.79-3.41 for the anodized aluminum junctions. The silver and gold coatings provide significant thermal enhancement; however, these coating-substrate combinations are susceptible to galvanic corrosion under some conditions.

  5. Metallic coatings for enhancement of thermal contact conductance

    SciTech Connect

    Lambert, M.A.; Fletcher, L.S. )

    1994-04-01

    The reliability of standard electronic modules may be improved by decreasing overall module temperature. This may be accomplished by enhancing the thermal contact conductance at the interface between the module frame guide rib and the card rail to which the module is clamped. Some metallic coatings, when applied to the card rail, would deform under load, increasing the contact area and associated conductance. This investigation evaluates the enhancements in thermal conductance afforded by vapor deposited silver and gold coatings. Experimental thermal conductance measurements were made for anodized aluminum 6101-T6 and electroless nickel-plated copper C11000-H03 card materials to the aluminum A356-T61 rail material. Conductance values for the electroless nickel-plated copper junction ranged from 600 to 2800 W/m(exp 2)K and those for the anodized aluminum junction ranged from 25 to 91 W/m(exp 2)K for contact pressures of 0.172-0.862 MPa and mean junction temperatures of 20-100 C. Experimental thermal conductance values of vapor deposited silver- and gold-coated aluminum A356-T61 rail surfaces indicate thermal enhancements of 1.25-2.19 for the electroless nickel-plated copper junctions and 1.79-3.41 for the anodized aluminum junctions. The silver and gold coatings provide significant thermal enhancement; however, these coating-substrate combinations are susceptible to galvanic corrosion under some conditions. 25 refs.

  6. Carbon Dioxide Separation with Novel Microporous Metal Organic Frameworks

    SciTech Connect

    Richard Willis; Annabelle Benin; John Low; Ganesh Venimadhavan; Syed Faheem; David Lesch; Adam Matzger; Randy Snurr

    2008-02-04

    The goal of this program was to develop a low cost novel sorbent to remove carbon dioxide from flue gas and gasification streams in electric utilities. Porous materials named metal-organic frameworks (MOFs) were found to have good capacity and selectivity for the capture of carbon dioxide. Several materials from the initial set of reference MOFs showed extremely high CO{sub 2} adsorption capacities and very desirable linear isotherm shapes. Sample preparation occurred at a high level, with a new family of materials suitable for intellectual property protection prepared and characterized. Raman spectroscopy was shown to be useful for the facile characterization of MOF materials during adsorption and especially, desorption. Further, the development of a Raman spectroscopic-based method of determining binary adsorption isotherms was initiated. It was discovered that a stronger base functionality will need to be added to MOF linkers in order to enhance CO{sub 2} selectivity over other gases via a chemisorption mechanism. A concentrated effort was expended on being able to accurately predict CO{sub 2} selectivities and on the calculation of predicted MOF surface area values from first principles. A method of modeling hydrolysis on MOF materials that correlates with experimental data was developed and refined. Complimentary experimental data were recorded via utilization of a combinatorial chemistry heat treatment unit and high-throughput X-ray diffractometer. The three main Deliverables for the project, namely (a) a MOF for pre-combustion (e.g., IGCC) CO{sub 2} capture, (b) a MOF for post-combustion (flue gas) CO{sub 2} capture, and (c) an assessment of commercial potential for a MOF in the IGCC application, were completed. The key properties for MOFs to work in this application - high CO{sub 2} capacity, good adsorption/desorption rates, high adsorption selectivity for CO{sub 2} over other gases such as methane and nitrogen, high stability to contaminants, namely

  7. Directional and enhanced spontaneous emission with a corrugated metal probe

    NASA Astrophysics Data System (ADS)

    Shen, Hongming; Lu, Guowei; He, Yingbo; Cheng, Yuqing; Liu, Haitao; Gong, Qihuang

    2014-06-01

    A three-dimensional corrugated metal tapered probe with surface corrugated gratings at the tip apex is proposed and investigated theoretically, which leads to an obvious emission beaming effect of spontaneous emission from a single emitter near the probe. In contrast with conventional apertureless metal probes, where only the enhancement of an optical near-field is concerned, the corrugated probe is able to manipulate local excitation intensity and far-field emission direction simultaneously. The angular emission from a single dipole source, being placed close to the corrugated probe, falls into a cone with a maximum directivity angle of +/-11.6°, which improves the collection efficiency 25-fold. Such a probe simultaneously increases the localized field intensity to about twice as strong as the conventional bare tip. In addition, the radiation pattern is sensitive to the working wavelength and the dipole to tip-apex separation. These findings make a promising route to the development of plasmonic spontaneous emission manipulation based on corrugated tapered antenna--for instance, tip-enhanced spectroscopy, single-molecule sensing, and single-photon source .

  8. Metal-organic frameworks with dynamic interlocked components

    NASA Astrophysics Data System (ADS)

    Vukotic, V. Nicholas; Harris, Kristopher J.; Zhu, Kelong; Schurko, Robert W.; Loeb, Stephen J.

    2012-06-01

    The dynamics of mechanically interlocked molecules such as rotaxanes and catenanes have been studied in solution as examples of rudimentary molecular switches and machines, but in this medium, the molecules are randomly dispersed and their motion incoherent. As a strategy for achieving a higher level of molecular organization, we have constructed a metal-organic framework material using a [2]rotaxane as the organic linker and binuclear Cu(II) units as the nodes. Activation of the as-synthesized material creates a void space inside the rigid framework that allows the soft macrocyclic ring of the [2]rotaxane to rotate rapidly, unimpeded by neighbouring molecular components. Variable-temperature 13C and 2H solid-state NMR experiments are used to characterize the nature and rate of the dynamic processes occurring inside this unique material. These results provide a blueprint for the future creation of solid-state molecular switches and molecular machines based on mechanically interlocked molecules.

  9. Pneumocystis Melanins Confer Enhanced Organism Viability

    PubMed Central

    Icenhour, Crystal R.; Kottom, Theodore J.; Limper, Andrew H.

    2006-01-01

    Pneumocystis continues to represent an important opportunistic fungal pathogen of those with compromised immunity. Thus, it is crucial to identify factors that affect its viability and pathogenicity. We previously reported the first identification of melanins in Pneumocystis. In the present study, we sought to further characterize these components and define the function for these melanins. Melanins extracted from Pneumocystis and melanized Pneumocystis cells were analyzed by electron spin resonance spectroscopy, revealing spectra consistent with melanins from other fungi. Immunofluorescence assays using anti-melanin monoclonal antibodies showed that melanins are widely present across Pneumocystis host species, including mouse-, ferret-, and human-derived Pneumocystis organisms, as well as Pneumocystis carinii derived from rat. Using immunoelectron microscopy, melanins were found to localize to the cell wall and cytoplasm of P. carinii cysts, as well as to intracystic bodies within mature cysts. Next, the role of melanins on the maintenance of Pneumocystis viability was determined by using quantitative reverse transcription-PCR measurement of the heat shock protein mRNA under adverse environmental conditions. Using a new method to promote the melanization of Pneumocystis, we observed that strongly melanized Pneumocystis retained viability to a greater degree when exposed to UV irradiation or desiccation compared to less-pigmented organisms. These studies support our previous identification of Pneumocystis melanins across the genus, further characterize these Pneumocystis components, and demonstrate that melanins protect Pneumocystis from environmental stressors. PMID:16757739

  10. Pneumocystis melanins confer enhanced organism viability.

    PubMed

    Icenhour, Crystal R; Kottom, Theodore J; Limper, Andrew H

    2006-06-01

    Pneumocystis continues to represent an important opportunistic fungal pathogen of those with compromised immunity. Thus, it is crucial to identify factors that affect its viability and pathogenicity. We previously reported the first identification of melanins in Pneumocystis. In the present study, we sought to further characterize these components and define the function for these melanins. Melanins extracted from Pneumocystis and melanized Pneumocystis cells were analyzed by electron spin resonance spectroscopy, revealing spectra consistent with melanins from other fungi. Immunofluorescence assays using anti-melanin monoclonal antibodies showed that melanins are widely present across Pneumocystis host species, including mouse-, ferret-, and human-derived Pneumocystis organisms, as well as Pneumocystis carinii derived from rat. Using immunoelectron microscopy, melanins were found to localize to the cell wall and cytoplasm of P. carinii cysts, as well as to intracystic bodies within mature cysts. Next, the role of melanins on the maintenance of Pneumocystis viability was determined by using quantitative reverse transcription-PCR measurement of the heat shock protein mRNA under adverse environmental conditions. Using a new method to promote the melanization of Pneumocystis, we observed that strongly melanized Pneumocystis retained viability to a greater degree when exposed to UV irradiation or desiccation compared to less-pigmented organisms. These studies support our previous identification of Pneumocystis melanins across the genus, further characterize these Pneumocystis components, and demonstrate that melanins protect Pneumocystis from environmental stressors.

  11. Photonic confinement in laterally structured metal-organic microcavities

    NASA Astrophysics Data System (ADS)

    Mischok, Andreas; Brückner, Robert; Sudzius, Markas; Reinhardt, Christoph; Lyssenko, Vadim G.; Fröb, Hartmut; Leo, Karl

    2014-08-01

    We investigate the formation of optical modes in organic microcavities with an incorporated perforated silver layer. The metal leads to a formation of Tamm-plasmon-polaritons and thus separates the sample into metal-free or metal-containing areas, supporting different resonances. This mode splitting is exploited to confine photons in elliptic holes and triangular cuts, forming distinctive standing wave patterns showing the strong lateral confinement. A comparison with a Maxwell-Bloch based rate equation model clearly shows the nonlinear transition into the lasing regime. The concentration of the electric field density and inhibition of lateral loss channels in turn decreases the lasing threshold by up to one order of magnitude, to 0.1 nJ. By spectroscopic investigation of such a triangular wedge, we observe the transition from the unperturbed cavity state to a strongly confined complex transversal mode. Such a structured silver layer can be utilized in future for charge carrier injection in an electrically driven organic solid state laser.

  12. Photonic confinement in laterally structured metal-organic microcavities

    SciTech Connect

    Mischok, Andreas Brückner, Robert; Sudzius, Markas; Reinhardt, Christoph; Lyssenko, Vadim G.; Fröb, Hartmut; Leo, Karl

    2014-08-04

    We investigate the formation of optical modes in organic microcavities with an incorporated perforated silver layer. The metal leads to a formation of Tamm-plasmon-polaritons and thus separates the sample into metal-free or metal-containing areas, supporting different resonances. This mode splitting is exploited to confine photons in elliptic holes and triangular cuts, forming distinctive standing wave patterns showing the strong lateral confinement. A comparison with a Maxwell-Bloch based rate equation model clearly shows the nonlinear transition into the lasing regime. The concentration of the electric field density and inhibition of lateral loss channels in turn decreases the lasing threshold by up to one order of magnitude, to 0.1 nJ. By spectroscopic investigation of such a triangular wedge, we observe the transition from the unperturbed cavity state to a strongly confined complex transversal mode. Such a structured silver layer can be utilized in future for charge carrier injection in an electrically driven organic solid state laser.

  13. Metal inhibition on the reactivity of manganese dioxide toward organic contaminant oxidation in relation to metal adsorption and ionic potential.

    PubMed

    Jiang, Jing; Wang, Zhuopu; Chen, Yang; He, Anfei; Li, Jianliang; Sheng, G Daniel

    2017-03-01

    Coexisting metal ions may significantly inhibit the oxidative reactivity of manganese oxides toward organic contaminants in metal-organic multi-pollutant waters. While the metal inhibition on the oxidation of organic contaminants by manganese oxides has previously been reported, the extent of the inhibition in relation to metal properties has not been established. Six alkali, alkaline, and transition metals, as well as two testing metals were evaluated for their abilities to inhibit the reactivity of birnessite. Regardless of the pathways of phenol and diuron oxidation (polymerization vs. breakdown), the extent of metal inhibition depended mainly on the metal itself and its concentration. The observed metal inhibition efficiency followed the order of Mn(2+) > Co(2+) > Cu(2+) > Al(3+) > Mg(2+) > K(+), consistent with metal adsorption on birnessite. The first-order organic oxidation rate constant (kobs) was linearly negatively correlated with metal adsorption (qe) on birnessite. These observations demonstrated that the metal inhibition efficiency was determined by metal adsorption on birnessite. The slopes of the kobs-qe varied among metals and followed the order of K(+) > Ca(2+) > Mg(2+) > Mn(2+) > Cd(2+) > Co(2+) > Cu(2+) > Al(3+). These slopes defined intrinsic inhibitory abilities of metals. As metals were adsorbed hydrated on birnessite, the intrinsic inhibitory ability was significantly linearly correlated with ionic potentials of metals, leading to a single straight line. Metals with multiple d electrons in the outermost orbit with polarizing energy that promotes hydrolysis sat slightly below the line, and vice versa.

  14. A highly porous metal-organic framework for large organic molecule capture and chromatographic separation.

    PubMed

    Li, Pei-Zhou; Su, Jie; Liang, Jie; Liu, Jia; Zhang, Yuanyuan; Chen, Hongzhong; Zhao, Yanli

    2017-03-25

    A highly porous metal-organic framework (MOF) with large pores was successfully obtained via solvothermal assembly of a "click"-extended tricarboxylate ligand and Zn(ii) ions. The inherent feature of large-molecule accessible pores endows the MOF with a unique property for utilization toward large guest molecules.

  15. Single molecule fluorescence studies of ribosome dynamics: An application of metal enhanced fluorescence

    NASA Astrophysics Data System (ADS)

    Bharill, Shashank

    Metal enhanced fluorescence (MEF), in which a surface plasmon near a noble metal alters the spectral properties of an organic fluorophore, has been reported to increase fluorescence intensity without a concomitant increase in photobleaching rate. The fluorescence intensities of Cy3- and Cy5-labeled ribosomal initiation complexes (ICs) near 50 nm silver particles were increased 4 - 7-fold compared to ICs in the absence of silver colloids. Photobleaching lifetime was not significantly decreased, resulting in 4 - 5.5-fold enhancement in total photon emission prior to photobleaching. Fluorophores showing enhanced fluorescence were located within ˜280 nm of the colloidal particles, as detected by light scattering and scanning probe microscopy. Aggregates of silver particles or larger colloids themselves produced wavelength-shifted luminescence similar to fluorescence, presumably due to resonant extinction between nearby metal particles. Intensity fluctuations above shot noise, at 0.1 - 5 Hz, were greater from slides containing colloidal particles than from plain glass. Overall signal to noise ratio was similar or slightly better near the silver particles. Proximity to silver particles did not compromise ribosome function, as measured by codon-dependent binding of fluorescent tRNA to the A site of fluorescent labeled ribosomes, dynamics of fluorescence resonance energy transfer between adjacent tRNAs in the ribosomal A and P sites, and elongation factor G catalyzed translocation.

  16. Improved Method Being Developed for Surface Enhancement of Metallic Materials

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.

    2001-01-01

    Surface enhancement methods induce a layer of beneficial residual compressive stress to improve the impact (FOD) resistance and fatigue life of metallic materials. A traditional method of surface enhancement often used is shot peening, in which small steel spheres are repeatedly impinged on metallic surfaces. Shot peening is inexpensive and widely used, but the plastic deformation of 20 to 40 percent imparted by the impacts can be harmful. This plastic deformation can damage the microstructure, severely limiting the ductility and durability of the material near the surface. It has also been shown to promote accelerated relaxation of the beneficial compressive residual stresses at elevated temperatures. Low-plasticity burnishing (LPB) is being developed as an improved method for the surface enhancement of metallic materials. LPB is being investigated as a rapid, inexpensive surface enhancement method under NASA Small Business Innovation Research contracts NAS3-98034 and NAS3-99116, with supporting characterization work at NASA. Previously, roller burnishing had been employed to refine surface finish. This concept was adopted and then optimized as a means of producing a layer of compressive stress of high magnitude and depth, with minimal plastic deformation (ref. 1). A simplified diagram of the developed process is given in the following figure. A single pass of a smooth, free-rolling spherical ball under a normal force deforms the surface of the material in tension, creating a compressive layer of residual stress. The ball is supported in a fluid with sufficient pressure to lift the ball off the surface of the retaining spherical socket. The ball is only in mechanical contact with the surface of the material being burnished and is free to roll on the surface. This apparatus is designed to be mounted in the conventional lathes and vertical mills currently used to machine parts. The process has been successfully applied to nickel-base superalloys by a team from the

  17. Solvothermal Metal Metathesis on a Metal-Organic Framework with Constricted Pores and the Study of Gas Separation.

    PubMed

    Li, Liangjun; Xue, Haitao; Wang, Ying; Zhao, Pinhui; Zhu, Dandan; Jiang, Min; Zhao, Xuebo

    2015-11-18

    Metal-organic frameworks (MOFs) with constricted pores can increase the adsorbate density of gas and facilitate effective CO2 separation from flue gas or natural gas due to their enhanced overlapping of potential fields of the pores. Herein, an MOF with constricted pores, which was formed by narrow channels and blocks of functional groups, was fabricated from the assembly of a methyl-functionalized ligand and Zn(II) centers (termed NPC-7-Zn). Structural analysis of the as-synthesized NPC-7-Zn reveals a series of zigzag pores with pore diameters of ∼0.7 nm, which could be favorable for CO2 traps. For reinforcing the framework stability, a solvothermal metal metathesis on the pristine MOF NPC-7-Zn was performed, and a new Cu(II) MOF (termed NPC-7-Cu) with an identical framework was produced. The influence of the reaction temperatures on the metal metathesis process was investigated. The results show that the constricted pores in NPC-7-Zn can induce kinetic issues that largely slow the metal metathesis process at room temperature. However, this kinetic issue can be solved by applying higher reaction temperatures. The modified MOF NPC-7-Cu exhibits significant improvements in framework stability and thus leads to a permanent porosity for this framework. The constricted pore structure enables enhanced potential fields for these pores, rendering this MOF with high adsorbate densities for CO2 and high adsorption selectivity for a CO2/N2 gas mixture. The adsorption kinetic studies reveal that CH4 has a faster diffusion rate constant than CO2, showing a surface diffusion controlled mechanism for CO2 and CH4 adsorption.

  18. Transition metal oxides for organic electronics: energetics, device physics and applications.

    PubMed

    Meyer, Jens; Hamwi, Sami; Kröger, Michael; Kowalsky, Wolfgang; Riedl, Thomas; Kahn, Antoine

    2012-10-23

    During the last few years, transition metal oxides (TMO) such as molybdenum tri-oxide (MoO(3) ), vanadium pent-oxide (V(2) O(5) ) or tungsten tri-oxide (WO(3) ) have been extensively studied because of their exceptional electronic properties for charge injection and extraction in organic electronic devices. These unique properties have led to the performance enhancement of several types of devices and to a variety of novel applications. TMOs have been used to realize efficient and long-term stable p-type doping of wide band gap organic materials, charge-generation junctions for stacked organic light emitting diodes (OLED), sputtering buffer layers for semi-transparent devices, and organic photovoltaic (OPV) cells with improved charge extraction, enhanced power conversion efficiency and substantially improved long term stability. Energetics in general play a key role in advancing device structure and performance in organic electronics; however, the literature provides a very inconsistent picture of the electronic structure of TMOs and the resulting interpretation of their role as functional constituents in organic electronics. With this review we intend to clarify some of the existing misconceptions. An overview of TMO-based device architectures ranging from transparent OLEDs to tandem OPV cells is also given. Various TMO film deposition methods are reviewed, addressing vacuum evaporation and recent approaches for solution-based processing. The specific properties of the resulting materials and their role as functional layers in organic devices are discussed.

  19. Solubility Enhanced Oxidation of Hydrophobic Organic Contaminants

    NASA Astrophysics Data System (ADS)

    Boving, T. B.; Eberle, D. E.; Ball, R.

    2012-12-01

    In-situ chemical oxidation (ISCO) is a remediation technique considered to be effective at overcoming some of the limitations of conventional subsurface treatment processes for volatile and semi-volatile organic contaminants (VOC, SVOC). ISCO reactions occur predominately in the aqueous phase and as a result, contaminant availability is a major limiting factor, i.e. contaminants with higher aqueous solubility's are typically more accessible for oxidation than more hydrophobic, sorbed compounds. The purpose of this study was to determine the feasibility of a new integrated desorption-oxidation process for the remediation of contaminated waters and sediments. Specifically, this study examined the potential of using hydroxypropyl-β-cyclodextrin (HPCD), a modified cyclic sugar, and a blend of oxidants commercially known as OxyZone® (U.S. patent No. 7,667,087) for the remediation of polycyclic aromatic hydrocarbons (PAH). Laboratory scale batch experiments confirmed prior studies that HPCD increases the aqueous concentration of these contaminants, making a greater mass of contaminant available for subsequent oxidation. When exposed to the same amount of oxidant, the mass of PAH destroyed increased linearly with increasing HPCD concentration. Relative to PAH saturated solutions without HPCD, 11 times more PAH mass was destroyed when a PAH saturated 15 g/L HPCD solution was treated with the same mass of oxidant. Destruction of the aqueous phase contaminants followed first order exponential decay kinetics in both deionized water and HPCD solutions. However, the destruction of complexed PAH was slower than for uncomplexed PAH. The cause of this is likely due to the preferential destruction of the HPCD molecule by the oxidant, followed by the subsequent oxidation of the PAH. The destruction of the cyclodextrin was minimized by modifying the oxidant formulation. Overall, these findings establish the potential of utilizing HPCD and OxyZone® as an integrated desorption

  20. Facile synthesis of multiple enzyme-containing metal-organic frameworks in a biomolecule-friendly environment.

    PubMed

    Wu, Xiaoling; Ge, Jun; Yang, Cheng; Hou, Miao; Liu, Zheng

    2015-09-07

    The one-step and facile synthesis of multi-enzyme-containing metal-organic framework (MOF) nanocrystals in aqueous solution at 25 °C was reported in this study. The GOx&HRP/ZIF-8 nanocomposite displayed high catalytic efficiency, high selectivity and enhanced stability due to the protecting effect of the framework.

  1. Chiral Cu(salen)-Based Metal-Organic Framework for Heterogeneously Catalyzed Aziridination and Amination of Olefins.

    PubMed

    Liu, Yan; Li, Zijian; Yuan, Guozan; Xia, Qingchun; Yuan, Chen; Cui, Yong

    2016-12-19

    A homochiral 3D porous metal-organic framework was assembled from a chiral dicarboxylic acid-functionalized Cu(salen)-based catalyst and could serve as an efficient heterogeneous catalyst for aziridination and allylic amination of olefins. Besides easy separation and reuse of the catalyst, the chiral framework confinement could impart substrate size selectivity, enhance catalyst activity, and induce product enantioselectivity.

  2. Correlated defect nanoregions in a metal-organic framework

    NASA Astrophysics Data System (ADS)

    Cliffe, Matthew J.; Wan, Wei; Zou, Xiaodong; Chater, Philip A.; Kleppe, Annette K.; Tucker, Matthew G.; Wilhelm, Heribert; Funnell, Nicholas P.; Coudert, François-Xavier; Goodwin, Andrew L.

    2014-06-01

    Throughout much of condensed matter science, correlated disorder is a key to material function. While structural and compositional defects are known to exist within a variety of metal-organic frameworks (MOFs), the prevailing understanding is that these defects are only ever included in a random manner. Here we show—using a combination of diffuse scattering, electron microscopy, anomalous X-ray scattering and pair distribution function measurements—that correlations between defects can in fact be introduced and controlled within a hafnium terephthalate MOF. The nanoscale defect structures that emerge are an analogue of correlated Schottky vacancies in rocksalt-structured transition metal monoxides and have implications for storage, transport, optical and mechanical responses. Our results suggest how the diffraction behaviour of some MOFs might be reinterpreted, and establish a strategy of exploiting correlated nanoscale disorder as a targetable and desirable motif in MOF design.

  3. Transformation of metal-organic frameworks for molecular sieving membranes

    PubMed Central

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-01-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively. PMID:27090597

  4. Boosting Responsivity of Organic-Metal Oxynitride Hybrid Heterointerface Phototransistor.

    PubMed

    Rim, You Seung; Ok, Kyung-Chul; Yang, Yang Michael; Chen, Huajun; Bae, Sang-Hoon; Wang, Chen; Huang, Yu; Park, Jin-Seong; Yang, Yang

    2016-06-15

    Amorphous metal oxides are attractive materials for various sensor applications, because of high electrical performance and easy processing. However, low absorption coefficient, slow photoresponse, and persistent photoconductivity of amorphous metal oxide films from the origin of deep-level defects are obstacles to their use as photonic applications. Here, we demonstrate ultrahigh photoresponsivity of organic-inorganic hybrid phototransistors featuring bulk heterojunction polymers and low-bandgap zinc oxynitride. Spontaneous formation of ultrathin zinc oxide on the surface of zinc oxynitride films could make an effective band-alignment for electron transfer from the dissociation of excitons in the bulk heterojunction, while holes were blocked by the deep highest occupied molecular orbital level of zinc oxide. These hybrid structure-based phototransistors are ultrasensitive to broad-bandwidth photons in ultraviolet to near-infrared regions. The detectivity and a linear dynamic range exceeded 10(12) Jones and 122.3 dB, respectively.

  5. Transformation of metal-organic frameworks for molecular sieving membranes

    NASA Astrophysics Data System (ADS)

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-04-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively.

  6. Theoretical Discovery of a Superconducting Two-Dimensional Metal-Organic Framework.

    PubMed

    Zhang, Xiaoming; Zhou, Yinong; Cui, Bin; Zhao, Mingwen; Liu, Feng

    2017-09-15

    Superconductivity is a fascinating quantum phenomenon characterized by zero electrical resistance and the Meissner effect. To date, several distinct families of superconductors (SCs) have been discovered. These include three-dimensional (3D) bulk SCs in both inorganic and organic materials as well as two-dimensional (2D) thin film SCs but only in inorganic materials. Here we predict superconductivity in 2D and 3D organic metal-organic frameworks by using first-principles calculations. We show that the highly conductive and recently synthesized Cu-benzenehexathial (BHT) is a Bardeen-Cooper-Schrieffer SC. Remarkably, the monolayer Cu-BHT has a critical temperature (Tc) of 4.43 K, while Tc of bulk Cu-BHT is 1.58 K. Different from the enhanced Tc in 2D inorganic SCs which is induced by interfacial effects, the Tc enhancement in this 2D organic SC is revealed to be the out-of-plane soft-mode vibrations, analogous to surface mode enhancement originally proposed by Ginzburg. Our findings not only shed new light on better understanding 2D superconductivity but also open a new direction to search for SCs by interface engineering with organic materials.

  7. Hydrogen storage by physisorption on Metal Organic Frameworks

    NASA Astrophysics Data System (ADS)

    Dailly, Anne

    2008-03-01

    Cryo-adsorption systems based on materials with high specific surface areas have the main advantage that they can store and release hydrogen with fast kinetics and high reversibility over multiples cycles. Recently Metal Organic Frameworks (MOFs) have been proposed as promising adsorbents for hydrogen. These crystallographically well organized hybrid solids resulting from the three dimensional connection of inorganic clusters using organic linkers show the largest specific surface areas of all known crystalline solids. The determination of the relationships between physical properties (chemistry, structure, surface area ) of the MOFs and their hydrogen storage behavior is a key step in the characterization of these materials, if they are to be designed for hydrogen storage applications. Excess hydrogen sorption measurements for different MOFs will be presented. We show that maximum hydrogen uptake at high pressure and 77K does not always scale with the specific surface area. A linear correlation trend only apply within a class of specific materials and breaks down when the surface area measurement does not represent the surface sites that are available to H2. The influence of pore size and shape will also be discussed by comparing several MOFs with different structure types. The hydrogen adsorption and binding energy at low pressure are strongly dependent on the metal ions and the pore size.

  8. Composites for removing metals and volatile organic compounds and method thereof

    DOEpatents

    Coronado, Paul R.; Coleman, Sabre J.; Reynolds, John G.

    2006-12-12

    Functionalized hydrophobic aerogel/solid support structure composites have been developed to remove metals and organic compounds from aqueous and vapor media. The targeted metals and organics are removed by passing the aqueous or vapor phase through the composite which can be in molded, granular, or powder form. The composites adsorb the metals and the organics leaving a purified aqueous or vapor stream. The species-specific adsorption occurs through specific functionalization of the aerogels tailored towards specific metals and/or organics. After adsorption, the composites can be disposed of or the targeted metals and/or organics can be reclaimed or removed and the composites recycled.

  9. Optical metal-organic framework sensor for selective discrimination of some toxic metal ions in water.

    PubMed

    Shahat, Ahmed; Hassan, Hassan M A; Azzazy, Hassan M E

    2013-09-02

    This paper reports the development of a facile and effective approach, based on the use of Zr-based metal-organic frameworks (UiO-66) sensor with micropores geometry, shape and particle morphology for the visual detection and removal of ultra-traces of some toxic metal ions such as Bi(III), Zn(II), Pb(II), Hg(II) and Cd(II). UiO-66 was used as selective carriers for accommodating hydrophobic chromophore probes such as dithizone (DZ) without coupling agent for sensitive and selective discrimination of trace level of toxic analytes. The developed UiO-66 sensor was utilized for the detection of ultra-traces of some toxic metal ions with the naked eye. The new sensor displays high sensitivity and selectivity of a wide range of detectable metals analytes up to 10(-10) mol dm(-3) in solution, in a rapid analyte uptake response (seconds). The developed sensor is stable, cost effective, easy to prepare, and would be useful for rapid detection and removal of ultra-traces of toxic metal ions in water samples.

  10. Metal-Organic Nanosheets Formed via Defect-Mediated Transformation of a Hafnium Metal-Organic Framework.

    PubMed

    Cliffe, Matthew J; Castillo-Martínez, Elizabeth; Wu, Yue; Lee, Jeongjae; Forse, Alexander C; Firth, Francesca C N; Moghadam, Peyman Z; Fairen-Jimenez, David; Gaultois, Michael W; Hill, Joshua A; Magdysyuk, Oxana V; Slater, Ben; Goodwin, Andrew L; Grey, Clare P

    2017-04-19

    We report a hafnium-containing MOF, hcp UiO-67(Hf), which is a ligand-deficient layered analogue of the face-centered cubic fcu UiO-67(Hf). hcp UiO-67 accommodates its lower ligand:metal ratio compared to fcu UiO-67 through a new structural mechanism: the formation of a condensed "double cluster" (Hf12O8(OH)14), analogous to the condensation of coordination polyhedra in oxide frameworks. In oxide frameworks, variable stoichiometry can lead to more complex defect structures, e.g., crystallographic shear planes or modules with differing compositions, which can be the source of further chemical reactivity; likewise, the layered hcp UiO-67 can react further to reversibly form a two-dimensional metal-organic framework, hxl UiO-67. Both three-dimensional hcp UiO-67 and two-dimensional hxl UiO-67 can be delaminated to form metal-organic nanosheets. Delamination of hcp UiO-67 occurs through the cleavage of strong hafnium-carboxylate bonds and is effected under mild conditions, suggesting that defect-ordered MOFs could be a productive route to porous two-dimensional materials.

  11. Polyamino acid functionalized membranes for metal capture and nanofiltration of organics: Modeling and experimental verification

    NASA Astrophysics Data System (ADS)

    Hestekin, Jamie Allen

    2000-10-01

    Passive membranes have been used for separations ranging from seawater desalination via reverse osmosis to the separation of particles with microfiltration membranes. However the attachment of macromolecules, with multiple functional sites, to microfiltration membranes allows for more selective separations. For these reasons, we have designed a novel membrane system, consisting of cellulose-based microfiltration membranes functionalized with polyamino acids (2,500--15,000 MW). Because of the high carboxyl content of the polyamino acids, these membranes have been shown to be extremely useful for the separation of heavy metals from aqueous solutions. The primary objective of this research was to establish the sorption mechanisms of functionalized microfiltration membranes and use these mechanisms to predict the rate behavior of metal transport through these membranes. Both cellulose acetate and pure cellulose were used as membrane support materials. Extensive experiments (pH 3--6) were conducted (under convective flow mode) with the derivatized membranes involving the heavy metals: lead, cadmium, nickel, copper, and selected mixtures with calcium in aqueous solutions. Metal sorption results were found to be a function of derivatization (aldehydes) density of membranes and degree of attachment of the polyfunctional groups, number of functional groups per chain, membrane surface area, and the type of metals to be sorbed. We have obtained metal sorption capacities as high as 1.5 g metal/g membrane. As opposed to homogeneous solution systems, the molar sorption capacities of the functional carboxyl sites are significantly enhanced in the membrane pores because of counterion condensation resulting partly from the extremely high charge densities in the membrane pores. This phenomenon was incorporated in a kinetic model for the prediction of sorption behavior. The model studied the effect of pore size, polyamino acid attachment density, pH, and metal type. Finally, in

  12. Fabrication of Porous Matrix Membrane (PMM) Using Metal-Organic Framework as Green Template for Water Treatment

    PubMed Central

    Lee, Jian-Yuan; Tang, Chuyang Y.; Huo, Fengwei

    2014-01-01

    Pressure-driven membranes with high porosity can potentially be fabricated by removing template, such as low water stability metal-organic frameworks (MOFs) or other nanoparticles, in polymeric matrix. We report on the use of benign MOFs as green template to enhance porosity and interconnectivity of the water treatment membranes. Significantly enhanced separation performance was observed which might be attributed to the mass transfer coefficient of the substrate layer increased in ultrafiltration (UF) application. PMID:24435326

  13. General Deposition of Metal-Organic Frameworks on Highly Adaptive Organic-Inorganic Hybrid Electrospun Fibrous Substrates.

    PubMed

    Liu, Chang; Wu, Yi-Nan; Morlay, Catherine; Gu, Yifan; Gebremariam, Binyam; Yuan, Xiao; Li, Fengting

    2016-02-03

    Electrospun nanofibrous mats are ideal substrates for metal-organic frameworks (MOFs) crystal deposition because of their specific structural parameters and chemical tenability. In this work, we utilized organic-inorganic hybrid electrospun fibrous mats as support material to study the deposition of various MOF particles. HKUST-1 and MIL-53(Al) were produced through solvothermal method, while ZIF-8 and MIL-88B(Fe) were prepared using microwave-induced heating method. The synthesis procedure for both methods were simple and effective because the hybrid nanofibrous mats showed considerable affinity to MOF particles and could be used without additional modifications. The obtained MOF composites exhibited effective incorporation between MOF particles and the porous substrates. MIL-53(Al) composite was applied as fibrous sorbent and showed enhanced adsorption capacity and removal rate, as well as easier operation, compared with thepowdered sample. Moreover, MIL-53(Al) composite was easier to be regenerated compared with powder form.

  14. Plasmonic Enhancement of Raman Signal using Complex Metallic Nanostructures based on DNA Origami

    NASA Astrophysics Data System (ADS)

    Finkelstein, Gleb

    2015-03-01

    DNA-based nanostructures, such as ``DNA origami,'' have recently emerged as one of the leading techniques for precise positioning of nanoscale materials in fields ranging from computer science to biomedical engineering. The origami is composed of a single scaffold DNA strand to which smaller ``staple`` strands are attached through DNA complementarity. The staples help to fold the scaffold strand into the designed structure of a predetermined shape. The resulting templates are highly addressable and have proven to be versatile tools for site-specific placement of various nanocomponents, such as metallic nanoparticles, quantum dots, fluorophores, etc. Building upon massively paralleled assembly mechanism of the origami and its ability to position nanocomponents, one may hope to utilize it for biosensing purposes. One attractive goal is the Raman spectroscopy, which provides a highly specific chemical fingerprint. Unfortunately, the Raman scattering cross section is small; Surface Enhanced Raman Spectroscopy (SERS) enhances the otherwise weak Raman signal by trapping the analyte molecules in the regions of intense electric field produced near rough metallic surfaces. These ``hot spots`` can be understood as resulting from localized surface plasmon modes resonantly exited by the incident laser excitation. We have earlier shown that metallic nanoparticles controllably attached to DNA origami can be further enlarged via an in-solution metallization; this technique allowed us to build metallic structures of complex topology. Recently, we have performed Raman spectroscopy of molecules attached to these metallic assemblies. Specifically, DNA origami is first used to organize the metallic structures, followed by a covalent attachment of Raman-active molecules to the metal. We found that the substrates with four nanoparticles per origami produce a strongly enhanced Raman signal compared to the control samples with only one nanoparticle per origami for the same particle

  15. Plasmonic effect-enhanced Ag nanodisk incorporated ZnO/Si metal-semiconductor-metal photodetectors

    NASA Astrophysics Data System (ADS)

    Kumar, Manjeet; Kojori, Hossein Shokri; Kim, Sung Jin; Park, Hyeong-Ho; Kim, Joondong; Yun, Ju-Hyung

    2016-10-01

    In this work, we present the enhancement of ultraviolet (UV) photodetection of Ag-ZnO thin film deposited by radio frequency magnetron sputtering. The surface morphological, optical, structural, and electrical properties of the deposited thin films were investigated by various characterization techniques. With this Ag-ZnO thin film structure and proper geometry of metal-semiconductor-metal (MSM) interdigitated structure design, photocurrent enhancement has been accomplished. MSM-photodetectors (PDs) using structures of Ag-ZnO gave a 30 times higher magnitude photocurrent at 340 nm of the wavelength. Plasmon-induced hot electrons contributed to improved spectral response to the UV region, while absorption and scattering effect enhanced broadband improvement to a response in the VIS-IR spectrum range. The improvement of Ag-ZnO PD in comparison with ZnO is attributed to the surface plasmon effect using Ag nanodisks. These results indicate that Ag-ZnO thin films can serve as excellent ultraviolet-PD and a very promising candidate for practical applications.

  16. Quantum dynamical simulations of local field enhancement in metal nanoparticles.

    PubMed

    Negre, Christian F A; Perassi, Eduardo M; Coronado, Eduardo A; Sánchez, Cristián G

    2013-03-27

    Field enhancements (Γ) around small Ag nanoparticles (NPs) are calculated using a quantum dynamical simulation formalism and the results are compared with electrodynamic simulations using the discrete dipole approximation (DDA) in order to address the important issue of the intrinsic atomistic structure of NPs. Quite remarkably, in both quantum and classical approaches the highest values of Γ are located in the same regions around single NPs. However, by introducing a complete atomistic description of the metallic NPs in optical simulations, a different pattern of the Γ distribution is obtained. Knowing the correct pattern of the Γ distribution around NPs is crucial for understanding the spectroscopic features of molecules inside hot spots. The enhancement produced by surface plasmon coupling is studied by using both approaches in NP dimers for different inter-particle distances. The results show that the trend of the variation of Γ versus inter-particle distance is different for classical and quantum simulations. This difference is explained in terms of a charge transfer mechanism that cannot be obtained with classical electrodynamics. Finally, time dependent distribution of the enhancement factor is simulated by introducing a time dependent field perturbation into the Hamiltonian, allowing an assessment of the localized surface plasmon resonance quantum dynamics.

  17. The surface chemistry of metal-organic frameworks.

    PubMed

    McGuire, Christina V; Forgan, Ross S

    2015-03-28

    Metal-organic frameworks (MOFs) have received particular attention over the last 20 years as a result of their attractive properties offering potential applications in a number of areas. Typically, these characteristics are tuned by functionalisation of the bulk of the MOF material itself. This Feature Article focuses instead on modification of MOF particles at their surfaces only, which can also offer control over the bulk properties of the material. The differing surface modification techniques available to the synthetic chemist will be discussed, with a focus on the effect of surface modification of MOFs on their fundamental properties and application in adsorption, catalysis, drug delivery and other areas.

  18. Nanostructure and hydrogen spillover of bridged metal-organic frameworks.

    PubMed

    Tsao, Cheng-Si; Yu, Ming-Sheng; Wang, Cheng-Yu; Liao, Pin-Yen; Chen, Hsin-Lung; Jeng, U-Ser; Tzeng, Yi-Ren; Chung, Tsui-Yun; Wu, Hsiu-Chu

    2009-02-04

    The metal-organic frameworks (MOF) with low and medium specific surface areas (SSA) were shown to be able to adsorb hydrogen via bridged spillover at room temperature (RT) up to an amount of full coverage of hydrogen in the MOF. Anomalous small-angle X-ray scattering was employed to investigate the key relationship between the structures and storage properties of the involved materials. It was found that the tunable imperfect lattice defects and the 3D pore network in the MOF crystal are the most critical structures for RT hydrogen uptake rather than the known micropores in the crystal, SSA, and Pt catalyst structure.

  19. Site characteristics in metal organic frameworks for gas adsorption

    NASA Astrophysics Data System (ADS)

    Uzun, Alper; Keskin, Seda

    2014-02-01

    Metal organic frameworks (MOFs) are a new class of nanoporous materials that have many potential advantages over traditional nanoporous materials for several chemical technologies including gas adsorption, catalysis, membrane-based gas separation, sensing, and biomedical devices. Knowledge on the interaction of guest molecules with the MOF surface is required to design and develop these MOF-based processes. In this review, we examine the importance of identification of gas adsorption sites in MOFs using the current state-of-the-art in experiments and computational modeling. This review provides guidelines to design new MOFs with useful surface properties that exhibit desired performances, such as high gas storage capacity, and high gas selectivity.

  20. Surface functionalization of metal organic frameworks for mixed matrix membranes

    DOEpatents

    Albenze, Erik; Lartey, Michael; Li, Tao; Luebke, David R.; Nulwala, Hunaid B.; Rosi, Nathaniel L.; Venna, Surendar R.

    2017-03-21

    Mixed Matrix Membrane (MMM) are composite membranes for gas separation and comprising a quantity of inorganic filler particles, in particular metal organic framework (MOF), dispersed throughout a polymer matrix comprising one or more polymers. This disclosure is directed to MOF functionalized through addition of a pendant functional group to the MOF, in order to improve interaction with a surrounding polymer matrix in a MMM. The improved interaction aids in avoiding defects in the MMM due to incompatible interfaces between the polymer matrix and the MOF particle, in turn increasing the mechanical and gas separation properties of the MMM. The disclosure is also directed to a MMM incorporating the surface functionalized MOF.

  1. Integration of Biomolecules with Metal-Organic Frameworks.

    PubMed

    Zhuang, Jia; Young, Allison P; Tsung, Chia-Kuang

    2017-08-01

    Owing to the progressive development of metal-organic-frameworks (MOFs) synthetic processes and considerable potential applications in last decade, integrating biomolecules into MOFs has recently gain considerable attention. Biomolecules, including lipids, oligopeptides, nucleic acids, and proteins have been readily incorporated into MOF systems via versatile formulation methods. The formed biomolecule-MOF hybrid structures have shown promising prospects in various fields, such as antitumor treatment, gene delivery, biomolecular sensing, and nanomotor device. By optimizing biomolecule integration methods while overcoming existing challenges, biomolecule-integrated MOF platforms are very promising to generate more practical applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Postsynthetic Tuning of Metal-Organic Frameworks for Targeted Applications.

    PubMed

    Islamoglu, Timur; Goswami, Subhadip; Li, Zhanyong; Howarth, Ashlee J; Farha, Omar K; Hupp, Joseph T

    2017-04-18

    Metal-organic frameworks (MOFs) are periodic, hybrid, atomically well-defined porous materials that typically form by self-assembly and consist of inorganic nodes (metal ions or clusters) and multitopic organic linkers. MOFs as a whole offer many intriguing properties, including ultrahigh porosity, tunable chemical functionality, and low density. These properties point to numerous potential applications, including gas storage, chemical separations, catalysis, light harvesting, and chemical sensing, to name a few. Reticular chemistry, or the linking of molecular building blocks into predetermined network structures, has been employed to synthesize thousands of MOFs. Given the vast library of candidate nodes and linkers, the number of potentially synthetically accessible MOFs is enormous. Nevertheless, a powerful complementary approach to obtain specific structures with desired chemical functionality is to modify known MOFs after synthesis. This approach is particularly useful when incorporation of particular chemical functionalities via direct synthesis is challenging or impossible. The challenges may stem from limited stability or solubility of precursors, unwanted secondary reactivity of precursors, or incompatibility of functional groups with the conditions needed for direct synthesis. MOFs can be postsynthetically modified by replacing the metal nodes and/or organic linkers or via functionalization of the metal nodes and/or organic linkers. Here we describe some of our efforts toward the development and application of postsynthetic strategies for imparting desired chemical functionalities in MOFs of known topology. The techniques include methods for functionalizing MOF nodes, i.e., solvent-assisted ligand incorporation (SALI) and atomic layer deposition in MOFs (AIM) as well as a method to replace structural linkers, termed solvent-assisted linker exchange (SALE), also known as postsynthethic exchange (PSE). For each functionalization strategy, we first describe

  3. Metal-organic frameworks for adsorption and separation of noble gases

    DOEpatents

    Allendorf, Mark D.; Greathouse, Jeffery A.; Staiger, Chad

    2017-05-30

    A method including exposing a gas mixture comprising a noble gas to a metal organic framework (MOF), including an organic electron donor and an adsorbent bed operable to adsorb a noble gas from a mixture of gases, the adsorbent bed including a metal organic framework (MOF) including an organic electron donor.

  4. Enhanced performance of dicationic ionic liquid electrolytes by organic solvents

    NASA Astrophysics Data System (ADS)

    Li, Song; Zhang, Pengfei; Fulvio Pasquale, F.; Hillesheim Patrick, C.; Feng, Guang; Dai, Sheng; Cummings Peter, T.

    2014-07-01

    The use of dicationic ionic liquid (DIL) electrolytes in supercapacitors is impeded by the slow dynamics of DILs, whereas the addition of organic solvents into DIL electrolytes improves ion transport and then enhances the power density of supercapacitors. In this work, the influences of organic solvents on the conductivity of DILs and the electrical double layer (EDL) of DIL-based supercapacitors are investigated using classical molecular dynamics simulation. Two types of organic solvents, acetonitrile (ACN) and propylene carbonate (PC), were used to explore the effects of different organic solvents on the EDL structure and capacitance of DIL/organic solvent-based supercapacitors. Firstly, it was found that the conductivity of DIL electrolytes was greatly enhanced in the presence of the organic solvent ACN. Secondly, a stronger adsorption of PC on graphite results in different EDL structures formed by DIL/ACN and DIL/PC electrolytes. The expulsion of co-ions from EDLs was observed in DIL/organic solvent electrolytes rather than neat DILs and this feature is more evident in DIL/PC. Furthermore, the bell-shaped differential capacitance-electric potential curve was not essentially changed by the presence of organic solvents. Comparing DIL/organic solvent electrolytes with neat DILs, the capacitance is slightly increased by organic solvents, which is in agreement with experimental observation.

  5. Enhanced performance of dicationic ionic liquid electrolytes by organic solvents.

    PubMed

    Li, Song; Zhang, Pengfei; Fulvio Pasquale, F; Hillesheim Patrick, C; Feng, Guang; Dai, Sheng; Cummings Peter, T

    2014-07-16

    The use of dicationic ionic liquid (DIL) electrolytes in supercapacitors is impeded by the slow dynamics of DILs, whereas the addition of organic solvents into DIL electrolytes improves ion transport and then enhances the power density of supercapacitors. In this work, the influences of organic solvents on the conductivity of DILs and the electrical double layer (EDL) of DIL-based supercapacitors are investigated using classical molecular dynamics simulation. Two types of organic solvents, acetonitrile (ACN) and propylene carbonate (PC), were used to explore the effects of different organic solvents on the EDL structure and capacitance of DIL/organic solvent-based supercapacitors. Firstly, it was found that the conductivity of DIL electrolytes was greatly enhanced in the presence of the organic solvent ACN. Secondly, a stronger adsorption of PC on graphite results in different EDL structures formed by DIL/ACN and DIL/PC electrolytes. The expulsion of co-ions from EDLs was observed in DIL/organic solvent electrolytes rather than neat DILs and this feature is more evident in DIL/PC. Furthermore, the bell-shaped differential capacitance-electric potential curve was not essentially changed by the presence of organic solvents. Comparing DIL/organic solvent electrolytes with neat DILs, the capacitance is slightly increased by organic solvents, which is in agreement with experimental observation.

  6. Semiconductor Metal-Organic Frameworks: Future Low-Bandgap Materials.

    PubMed

    Usman, Muhammad; Mendiratta, Shruti; Lu, Kuang-Lieh

    2017-02-01

    Metal-organic frameworks (MOFs) with low density, high porosity, and easy tunability of functionality and structural properties, represent potential candidates for use as semiconductor materials. The rapid development of the semiconductor industry and the continuous miniaturization of feature sizes of integrated circuits toward the nanometer (nm) scale require novel semiconductor materials instead of traditional materials like silicon, germanium, and gallium arsenide etc. MOFs with advantageous properties of both the inorganic and the organic components promise to serve as the next generation of semiconductor materials for the microelectronics industry with the potential to be extremely stable, cheap, and mechanically flexible. Here, a perspective of recent research is provided, regarding the semiconducting properties of MOFs, bandgap studies, and their potential in microelectronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. "Heterogeneity within order" in metal-organic frameworks.

    PubMed

    Furukawa, Hiroyasu; Müller, Ulrich; Yaghi, Omar M

    2015-03-09

    Metal-organic frameworks (MOFs) are constructed by linking inorganic units with organic linkers to make extended networks. Though more than 20 000 MOF structures have been reported most of these are ordered and largely composed of a limited number of different kinds building units, and very few have multiple different building units (heterogeneous). Although heterogeneity and multiplicity is a fundamental characteristic of biological systems, very few synthetic materials incorporate heterogeneity without losing crystalline order. Thus, the question arises: how do we introduce heterogeneity into MOFs without losing their ordered structure? This Review outlines strategies for varying the building units within both the backbone of the MOF and its pores to produce the heterogeneity that is sought after. The impact this heterogeneity imparts on the properties of a MOF is highlighted. We also provide an update on the MOF industry as part of this themed issue for the 150th anniversary of BASF.

  8. Organic nano-floating-gate transistor memory with metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Van Tho, Luu; Baeg, Kang-Jun; Noh, Yong-Young

    2016-04-01

    Organic non-volatile memory is advanced topics for various soft electronics applications as lightweight, low-cost, flexible, and printable solid-state data storage media. As a key building block, organic field-effect transistors (OFETs) with a nano-floating gate are widely used and promising structures to store digital information stably in a memory cell. Different types of nano-floating-gates and their various synthesis methods have been developed and applied to fabricate nanoparticle-based non-volatile memory devices. In this review, recent advances in the classes of nano-floating-gate OFET memory devices using metal nanoparticles as charge-trapping sites are briefly reviewed. Details of device fabrication, characterization, and operation mechanisms are reported based on recent research activities reported in the literature.

  9. Organic nano-floating-gate transistor memory with metal nanoparticles.

    PubMed

    Van Tho, Luu; Baeg, Kang-Jun; Noh, Yong-Young

    2016-01-01

    Organic non-volatile memory is advanced topics for various soft electronics applications as lightweight, low-cost, flexible, and printable solid-state data storage media. As a key building block, organic field-effect transistors (OFETs) with a nano-floating gate are widely used and promising structures to store digital information stably in a memory cell. Different types of nano-floating-gates and their various synthesis methods have been developed and applied to fabricate nanoparticle-based non-volatile memory devices. In this review, recent advances in the classes of nano-floating-gate OFET memory devices using metal nanoparticles as charge-trapping sites are briefly reviewed. Details of device fabrication, characterization, and operation mechanisms are reported based on recent research activities reported in the literature.

  10. Enhanced Raman spectroscopic study of rotational isomers on metal surfaces

    NASA Technical Reports Server (NTRS)

    Loo, B. H.; Lee, Y. G.; Frazier, D. O.

    1986-01-01

    Surfaced-enhanced Raman spectroscopy has been used to study rotational isomers of succinonitrile and N-methyl-thioacetamide on Cu and Ag surfaces. Both the gauche and trans conformers of succinonitrile are found to chemisorb on the metal surface. The doubly degenerate nu(C-triple bond-N) in the free molecules is removed when succinonitrile adsorbs on copper, which indicates that the two (C-triple bond-N) groups are no longer chemically equivalent. Both conformers are found to coordinate to the copper surface through the pi system of one of the two (C-triple bond-N) groups. In the case of N-methyl-thioacetamide, the population of the cis isomer is greatly increased on Cu and Ag surfaces. This is probably due to surface-induced cis-trans isomerization, in which the predominant trans isomer is converted to the cis isomer.

  11. Engineering Metallic Nanoparticles for Enhancing and Probing Catalytic Reactions.

    PubMed

    Collins, Gillian; Holmes, Justin D

    2016-07-01

    Recent developments in tailoring the structural and chemical properties of colloidal metal nanoparticles (NPs) have led to significant enhancements in catalyst performance. Controllable colloidal synthesis has also allowed tailor-made NPs to serve as mechanistic probes for catalytic processes. The innovative use of colloidal NPs to gain fundamental insights into catalytic function will be highlighted across a variety of catalytic and electrocatalytic applications. The engineering of future heterogenous catalysts is also moving beyond size, shape and composition considerations. Advancements in understanding structure-property relationships have enabled incorporation of complex features such as tuning surface strain to influence the behavior of catalytic NPs. Exploiting plasmonic properties and altering colloidal surface chemistry through functionalization are also emerging as important areas for rational design of catalytic NPs. This news article will highlight the key developments and challenges to the future design of catalytic NPs.

  12. Magnetic moment formation in metal-organic monolayers

    NASA Astrophysics Data System (ADS)

    Mabrouk, Manel; Hayn, Roland

    2015-11-01

    We investigate the electronic and magnetic properties of a two-dimensional polymeric manganese phthalocyanine (Mn-Pc) network and its derivative, the metal-ligand network Mn-TCNB formed by the transition-metal atom Mn and the organic ligand TCNB (1,2,4,5-tetracyanobenzene), using first-principles calculations on the basis of density functional theory (DFT) with the Hubbard-like Coulomb term. Our calculations show that Mn-Pc and Mn-TCNB are metallic. It is found that the Mn-Pc network is more stable than the Mn-TCNB one, and both have a total magnetic moment of about 3 μB . In the case of Mn-Pc, also the local Mn moment is close to 3 μB . But in Mn-TCNB, we find a high spin state S =5 /2 at Mn that is partially screened by unpaired electrons at the ligands. That screening is static in the DFT + U results, but we argue in favor of a dynamical screening in reality. Using our proper model calculation on the basis of a suitable model Hamiltonian, we explain the ab initio calculations, analyze the partial screening effect that exists in the two-dimensional Mn-TCNB network, and compare both systems.

  13. Sulfate Reduction Remediation of a Metals Plume Through Organic Injection

    SciTech Connect

    Phifer, M.A.

    2003-03-11

    Laboratory testing and a field-scale demonstration for the sulfate reduction remediation of an acidic/metals/sulfate groundwater plume at the Savannah River Site has been conducted. The laboratory testing consisted of the use of anaerobic microcosms to test the viability of three organic substrates to promote microbially mediated sulfate reduction. Based upon the laboratory testing, soybean oil and sodium lactate were selected for injection during the subsequent field-scale demonstration. The field-scale demonstration is currently ongoing. Approximately 825 gallons (3,123 L) of soybean oil and 225 gallons (852 L) of 60 percent sodium lactate have been injected into an existing well system within the plume. Since the injections, sulfate concentrations in the injection zone have significantly decreased, sulfate-reducing bacteria concentrations have significantly increased, the pH has increased, the Eh has decreased, and the concentrations of many metals have decreased. Microbially mediated sulfate reduction has been successfully promoted for the remediation of the acidic/metals/sulfate plume by the injection of soybean oil and sodium lactate within the plume.

  14. Synthetic Modularity of Protein-Metal-Organic Frameworks.

    PubMed

    Bailey, Jake B; Zhang, Ling; Chiong, Jerika A; Ahn, Sunhyung; Tezcan, F Akif

    2017-06-21

    Previously, we adopted the construction principles of metal-organic frameworks (MOFs) to design a 3D crystalline protein lattice in which pseudospherical ferritin nodes decorated on their C3 symmetric vertices with Zn coordination sites were connected via a ditopic benzene-dihydroxamate linker. In this work, we have systematically varied both the metal ions presented at the vertices of the ferritin nodes (Zn(II), Ni(II), and Co(II)) and the synthetic dihydroxamate linkers, which yielded an expanded library of 15 ferritin-MOFs with the expected body-centered (cubic or tetragonal) lattice arrangements. Crystallographic and small-angle X-ray scattering (SAXS) analyses indicate that lattice symmetries and dimensions of ferritin-MOFs can be dictated by both the metal and linker components. SAXS measurements on bulk crystalline samples reveal that some ferritin-MOFs can adopt multiple lattice conformations, suggesting dynamic behavior. This work establishes that the self-assembly of ferritin-MOFs is highly robust and that the synthetic modularity that underlies the structural diversity of conventional MOFs can also be applied to the self-assembly of protein-based crystalline materials.

  15. Embedded insulated metallic nanopatterns for enhanced optical absorption and photovoltaics

    NASA Astrophysics Data System (ADS)

    Ye, Fan; Burns, Michael J.; Naughton, Michael J.

    2012-02-01

    Recently, we have shown embedded metallic nanopatterns (EMN) in ultrathin PV films to be candidates for high efficiency thin-film solar cells, owing to prominent metamaterial/plasmonic-enhanced light trapping, as compared to unpatterned, surface- or bottom-patterned [1]. We also showed that hot electron effects emerge in ultrathin a-Si-based solar cells [2]. The EMN in the semiconductor layer, however, can also serve as a source of recombination for photogenerated electrons and holes, leading to decreased current. Here, we propose the idea of an embedded insulated metallic nanopattern (EIMN) to efficiently avoid the recombination effect while maintaining high light absorption in an ultrathin film format in which hot electron physics can contribute. Simulations show that an EIMN with a 10 nm layer of dielectric insulation provides essentially the same absorption as its EMN counterpart. Measurements on several EMN structures will be presented. This EIMN architecture may provide a practical route to high efficiency, hot electron solar cell technology using ultrathin films.[1]F. Ye, M.J. Burns, M.J. Naughton, Proc. SPIE 8111, 811103 (2011).[2]K. Kempa, M.J. Naughton, Z.F. Ren, A. Herczynski, T. Kirkpatrick, J. Rybczynski, Y. Gao, Appl. Phys. Lett. 95, 233121(2009)

  16. Tuning hydrogen sorption properties of metal-organic frameworks by postsynthetic covalent modification.

    PubMed

    Wang, Zhenqiang; Tanabe, Kristine K; Cohen, Seth M

    2010-01-04

    Postsynthetic modification is presented as a means to tune the hydrogen adsorption properties of a series of metal-organic frameworks (MOFs). IRMOF-3 (isoreticular metal-organic framework), UMCM-1-NH(2) (University of Michigan crystalline material), and DMOF-1-NH(2) (DABCO metal-organic framework) have been covalently modified with a series of anhydrides or isocyanates and the hydrogen sorption properties have been studied. Both the storage capacities and isosteric heats of adsorption clearly show that covalent postsynthetic modification can significantly enhance the sorption affinity of MOFs with hydrogen and in some cases increase both gravimetric and volumetric uptake of the gas as much as 40 %. The significance of the present study is illustrated by: 1) the nature of the substituents introduced by postsynthetic modification result in different effects on the binding of hydrogen; 2) the covalent postsynthetic modification approach allows for systematic modulation of hydrogen sorption properties; and 3) the ease of postsynthetic modification of MOFs allows a direct evaluation of the interplay between MOF structure, hydrogen uptake, and heat of adsorption. The findings presented herein show that postsynthetic modification is a powerful method to manipulate and better understand the gas sorption properties of MOFs.

  17. Growth, physiological and molecular traits in Salicaceae trees investigated for phytoremediation of heavy metals and organics.

    PubMed

    Marmiroli, Marta; Pietrini, Fabrizio; Maestri, Elena; Zacchini, Massimo; Marmiroli, Nelson; Massacci, Angelo

    2011-12-01

    Worldwide, there are many large areas moderately contaminated with heavy metals and/or organics that have not been remediated due to the high cost and technical drawbacks of currently available technologies. Methods with a good potential for coping with these limitations are emerging from phytoremediation techniques, using, for example, specific amendments and/or plants selected from various candidates proven in several investigations to be reasonably efficient in extracting heavy metals from soil or water, or in co-metabolizing organics with bacteria flourishing or inoculated in their rhizospheres. Populus and Salix spp., two genera belonging to the Salicaceae family, include genotypes that can be considered among the candidates for this phytoremediation approach. This review shows the recent improvements in analytical tools based on the identification of useful genetic diversity associated with classical growth, physiological and biochemical traits, and the importance of plant genotype selection for enhancing phytoremediation efficiency. Particularly interesting are studies on the application of the phytoremediation of heavy metals and of chlorinated organics, in which microorganisms selected for their degradation capabilities were bioaugmented in the rhizosphere of Salicaceae planted at a high density for biomass and bioenergy production.

  18. A metal-free organic-inorganic aqueous flow battery.

    PubMed

    Huskinson, Brian; Marshak, Michael P; Suh, Changwon; Er, Süleyman; Gerhardt, Michael R; Galvin, Cooper J; Chen, Xudong; Aspuru-Guzik, Alán; Gordon, Roy G; Aziz, Michael J

    2014-01-09

    As the fraction of electricity generation from intermittent renewable sources--such as solar or wind--grows, the ability to store large amounts of electrical energy is of increasing importance. Solid-electrode batteries maintain discharge at peak power for far too short a time to fully regulate wind or solar power output. In contrast, flow batteries can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all of the electro-active species in fluid form. Wide-scale utilization of flow batteries is, however, limited by the abundance and cost of these materials, particularly those using redox-active metals and precious-metal electrocatalysts. Here we describe a class of energy storage materials that exploits the favourable chemical and electrochemical properties of a family of molecules known as quinones. The example we demonstrate is a metal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid (AQDS). AQDS undergoes extremely rapid and reversible two-electron two-proton reduction on a glassy carbon electrode in sulphuric acid. An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br2/Br(-) redox couple, yields a peak galvanic power density exceeding 0.6 W cm(-2) at 1.3 A cm(-2). Cycling of this quinone-bromide flow battery showed >99 per cent storage capacity retention per cycle. The organic anthraquinone species can be synthesized from inexpensive commodity chemicals. This organic approach permits tuning of important properties such as the reduction potential and solubility by adding functional groups: for example, we demonstrate that the addition of two hydroxy groups to AQDS increases the open circuit potential of the cell by 11% and we describe a pathway for further increases in cell voltage. The use of π-aromatic redox-active organic molecules instead of redox-active metals

  19. A metal-free organic-inorganic aqueous flow battery

    NASA Astrophysics Data System (ADS)

    Huskinson, Brian; Marshak, Michael P.; Suh, Changwon; Er, Süleyman; Gerhardt, Michael R.; Galvin, Cooper J.; Chen, Xudong; Aspuru-Guzik, Alán; Gordon, Roy G.; Aziz, Michael J.

    2014-01-01

    As the fraction of electricity generation from intermittent renewable sources--such as solar or wind--grows, the ability to store large amounts of electrical energy is of increasing importance. Solid-electrode batteries maintain discharge at peak power for far too short a time to fully regulate wind or solar power output. In contrast, flow batteries can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all of the electro-active species in fluid form. Wide-scale utilization of flow batteries is, however, limited by the abundance and cost of these materials, particularly those using redox-active metals and precious-metal electrocatalysts. Here we describe a class of energy storage materials that exploits the favourable chemical and electrochemical properties of a family of molecules known as quinones. The example we demonstrate is a metal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid (AQDS). AQDS undergoes extremely rapid and reversible two-electron two-proton reduction on a glassy carbon electrode in sulphuric acid. An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br2/Br- redox couple, yields a peak galvanic power density exceeding 0.6Wcm-2 at 1.3Acm-2. Cycling of this quinone-bromide flow battery showed >99 per cent storage capacity retention per cycle. The organic anthraquinone species can be synthesized from inexpensive commodity chemicals. This organic approach permits tuning of important properties such as the reduction potential and solubility by adding functional groups: for example, we demonstrate that the addition of two hydroxy groups to AQDS increases the open circuit potential of the cell by 11% and we describe a pathway for further increases in cell voltage. The use of π-aromatic redox-active organic molecules instead of redox-active metals represents a new and

  20. The influence of the enantiomeric ratio of an organic ligand on the structure and chirality of Metal-Organic Frameworks

    PubMed Central

    Burneo, Iván; Stylianou, Kyriakos C.; Imaz, Inhar; Maspoch, Daniel

    2016-01-01

    We have prepared three distinct polyamino acid-based metal-organic frameworks (MOFs) with different chirality and porosity using the same chemistry, by simply modifying the enantiomeric ratio of the chiral organic ligand used. PMID:25253285