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1.
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2.
  • Akhtar, Farid, et al. (författare)
  • Strong and binder free structured zeolite sorbents with very high CO 2-over-N 2 selectivities and high capacities to adsorb CO 2 rapidly
  • 2012
  • Ingår i: Energy & Environmental Science. - 1754-5692 .- 1754-5706. ; 5:6, s. 7664-7673
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Mechanically strong monoliths of zeolite NaKA with a hierarchy of pores displayed very high CO2-over-N2 selectivity. The zeolite monoliths were produced by pulsed current processing (PCP) without the use of added binders and with a preserved microporous crystal structure. Adsorption isotherms of CO2 and N2 were determined and used to predict the co-adsorption of CO2 and N2 using ideal adsorbed solution theory (IAST). The IAST predictions showed that monolithic adsorbents of NaKA could reach an extraordinarily high CO2-over-N2 selectivity in a binary mixture with a composition similar to flue gas (15 mol% CO2 and 85 mol% N2 at 25 °C and 101 kPa). Structured NaKA monoliths with a K+ content of 9.9 at% combined a CO2-over-N2 selectivity of >1100 with a high CO2 adsorption capacity (4 mmol g−1) and a fast adsorption kinetics (on the order of one minute). Estimates of a figure of merit (F) based on IAST CO2-over-N2 selectivity, and time-dependent CO2 uptake capacity, suggest that PCP-produced structured NaKA with a K+ content of 9.9 at% offers a performance far superior to 13X adsorbents, in particular at short cycle times.</p>
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3.
  • Akhtar, Farid, et al. (författare)
  • Strong and binder free structured zeolite sorbents with very high CO2-over-N-2 selectivities and high capacities to adsorb CO2 rapidly
  • 2012
  • Ingår i: Energy & Environmental Science. - 1754-5692 .- 1754-5706. ; 5:6, s. 7664-7673
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Mechanically strong monoliths of zeolite NaKA with a hierarchy of pores displayed very high CO2-over-N-2 selectivity. The zeolite monoliths were produced by pulsed current processing (PCP) without the use of added binders and with a preserved microporous crystal structure. Adsorption isotherms of CO2 and N-2 were determined and used to predict the co-adsorption of CO2 and N-2 using ideal adsorbed solution theory (IAST). The IAST predictions showed that monolithic adsorbents of NaKA could reach an extraordinarily high CO2-over-N-2 selectivity in a binary mixture with a composition similar to flue gas (15 mol% CO2 and 85 mol% N2 at 25 degrees C and 101 kPa). Structured NaKA monoliths with a K+ content of 9.9 at% combined a CO2-over-N-2 selectivity of &gt;1100 with a high CO2 adsorption capacity (4 mmol g(-1)) and a fast adsorption kinetics (on the order of one minute). Estimates of a figure of merit (F) based on IAST CO2-over-N-2 selectivity, and time-dependent CO2 uptake capacity, suggest that PCP-produced structured NaKA with a K+ content of 9.9 at% offers a performance far superior to 13X adsorbents, in particular at short cycle times.</p>
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4.
  • Beckmann, Katrin, et al. (författare)
  • Formation of stoichiometrically 18O-labelled oxygen from the oxidation of 18O-enriched water mediated by a dinuclear manganese complex-a mass spectrometry and EPR study
  • 2008
  • Ingår i: Energy & Environmental Science. - 1754-5692 .- 1754-5706. ; 1, s. 668-76
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Oxygen formation was detected for the oxidations of various multinuclear manganese complexes by oxone (HSO5-) in aqueous solution. To determine to what extent water was the source of the evolved O2, H218O isotope-labelling experiments coupled with membrane inlet mass spectrometry (MIMS) were carried out. We discovered that during the reaction of oxone with [Mn2(OAc)2(bpmp)]+ (1), stoichiometrically labelled oxygen (18O2) was formed. This is the first example of a homogeneous reaction mediated by a synthetic manganese complex where the addition of a strong chemical oxidant yields 18O2 with labelling percentages matching the theoretically expected values for the case of both O-atoms originating from water. Experiments using lead acetate as an alternative oxidant supported this finding. A detailed investigation of the reaction by EPR spectroscopy, MIMS and Clark-type oxygen detection enabled us to propose potential reaction pathways.</p>
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5.
  • Beckmann, K., et al. (författare)
  • Formation of stoichiometrically O-18-labelled oxygen from the oxidation of O-18-enriched water mediated by a dinuclear manganese complex : a mass spectrometry and EPR study
  • 2008
  • Ingår i: Energy & Environmental Science. - 1754-5692 .- 1754-5706. - 1754-5692 ; 1:6, s. 668-676
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Oxygen formation was detected for the oxidations of various multinuclear manganese complexes by oxone (HSO5-) in aqueous solution. To determine to what extent water was the source of the evolved O-2, (H2O)-O-18 isotope-labelling experiments coupled with membrane inlet mass spectrometry (MIMS) were carried out. We discovered that during the reaction of oxone with [Mn-2(OAc)(2)(bpmp)](+) (1), stoichiometrically labelled oxygen (O-18(2)) was formed. This is the first example of a homogeneous reaction mediated by a synthetic manganese complex where the addition of a strong chemical oxidant yields O-18(2) with labelling percentages matching the theoretically expected values for the case of both O-atoms originating from water. Experiments using lead acetate as an alternative oxidant supported this finding. A detailed investigation of the reaction by EPR spectroscopy, MIMS and Clark-type oxygen detection enabled us to propose potential reaction pathways.</p>
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6.
  • Bertoni, M. I., 1967-, et al. (författare)
  • Nanoprobe X-ray fluorescence characterization of defects in large-area solar cells
  • 2011
  • Ingår i: Energy & Environmental Science. - 1754-5692 .- 1754-5706. ; 4, s. 4252-4257
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>The performance of centimeter-sized energy devices is regulated by inhomogeneously distributednanoscale defects. To improve device efficiency and reduce cost, accurate characterization of thesenanoscale defects is necessary. However, the multiscale nature of this problem presentsa characterization challenge, as non-destructive techniques often specialize in a single decade of lengthscales, and have difficulty probing non-destructively beneath the surface of materials with sub-micronspatial resolution. Herein, we push the resolution limits of synchrotron-based nanoprobe X-rayfluorescence mapping to 80 nm, to investigate a recombination-active intragranular defect in industrialsolar cells. Our nano-XRF measurements distinguish fundamental differences between benign anddeleterious dislocations in solar cell devices: we observe recombination-active dislocations to containa high degree of nanoscale iron and copper decoration, while recombination-inactive dislocationsappear clean. Statistically meaningful high-resolution measurements establish a connection betweencommercially relevant materials and previous fundamental studies on intentionally contaminatedmodel defect structures, pointing the way towards optimization of the industrial solar cell process.Moreover, this study presents a hierarchical characterization approach that can be broadly extended toother nanodefect-limited energy systems with the advent of high-resolution X-ray imaging beamlines</p>
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7.
  • Bubnova, Olga, et al. (författare)
  • Towards polymer-based organic thermoelectric generators
  • 2012
  • Ingår i: Energy & Environmental Science. - Royal Society of Chemistry. - 1754-5692 .- 1754-5706. ; 5:11, s. 9345-9362
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>In response to the thread of environmental and ecological degradation along with projected fossil fuel depletion the active search for efficient renewable energy conversion technologies has been attempted in various research areas including the field of thermoelectrics. Despite the availability of considerable amounts of waste and natural heat stored in warm fluids (andlt;250 degrees C) a lack of environmentally friendly materials with high natural abundance, low manufacturing cost and high thermoelectric efficiency impedes the widespread use of thermoelectric generators for energy harvesting on a large scale. In this perspective, we examine the possibility of using organic conducting polymers in thermoelectric applications. We provide an overview of the background and the key concepts of organic thermoelectrics and illustrate some of the first prototypes of polymer-based organic thermoelectric generators.</p>
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8.
  • Chen, Lin, et al. (författare)
  • A super-efficient cobalt catalyst for electrochemical hydrogen production from neutral water with 80 mV overpotential
  • 2014
  • Ingår i: Energy & Environmental Science. - 1754-5692 .- 1754-5706. ; 7:1, s. 329-334
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Self-assembled molecular iron and cobalt catalysts (MP4N2, M = Fe, Co) bearing a multihydroxy-functionalized tetraphosphine ligand electrocatalyze H-2 generation from neutral water on a mercury electrode at -1.03 and -0.50 V vs. NHE, respectively. Complex CoP4N2 displays extremely low overpotential (E-onset = 80 mV) while maintaining high activity and good stability. Bulk electrolysis of CoP4N2 in a neutral phosphate buffer solution at -1.0 V vs. NHE produced 9.24 x 10(4) mol H-2 per mol cat. over 20 h, with a Faradaic efficiency close to 100% and without apparent deactivation.</p>
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9.
  • Cheng, Ming, et al. (författare)
  • Efficient dye-sensitized solar cells based on an iodine-free electrolyte using L-cysteine/L-cystine as a redox couple
  • 2012
  • Ingår i: Energy & Environmental Science. - 1754-5692 .- 1754-5706. ; 5:4, s. 6290-6293
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>A new iodine-free electrolyte based on amino acids L-cysteine/L-cystine as a redox couple has been designed and synthesized. DSSCs fabricated with the conventional I-/I-3(-) redox couple gave efficiencies of 8.1% and 6.3% under optimized experimental conditions based on ruthenium dye, N719, and metal-free organic dye, TH202, respectively. Based on the same dyes, the DSSCs employing the new L-cysteine/L-cystine redox couple showed comparable efficiencies of 7.7% and 5.6%, respectively. However, higher incident-photon-to-electron (IPCE) conversion efficiencies and larger J(sc) values were found for devices with the L-cysteine/L-cystine redox couple than with I-/I-3(-). From an electrochemical impedance spectroscopic study, we found that the charge recombination between the conduction band electrons in the TiO2 film and the electrolyte containing the L-cysteine/L-cystine redox couple is restrained.</p>
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10.
  • Cong, Jiayan, et al. (författare)
  • Iodine/iodide-free redox shuttles for liquid electrolyte-based dye-sensitized solar cells
  • 2012
  • Ingår i: Energy & Environmental Science. - Royal Society of Chemistry. - 1754-5692 .- 1754-5706. ; 5:11, s. 9180-9194
  • Forskningsöversikt (refereegranskat)abstract
    • <p>Dye-sensitized solar cells have attracted intense academic interest over the past two decades. For a long time, the development of new redox systems has fallen far behind that of the sensitizing dyes and other materials. However, the field has received renewed attention recently. In particular, in 2011, the Gratzel group published a record DSC efficiency of 12.3% by using a new Co-complex-based electrolyte. In this review, we will provide an overview of iodine/iodide-free redox systems for liquid electrolytes, and reveal that the design of an efficient redox system should combine with appropriate sensitizing dyes which is the pivotal challenge for highly efficient DSCs.</p>
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