摘要:
A hybrid polymer/inorganic membrane with dual transport pathways overcomes traditional limitations. The inorganic phase consists of a metal-organic framework (MOF), which is an ideal inorganic dispersant to construct dual transport pathways as the crystalline porous structure of MOFs is more amenable to molecular diffusion than polymers. Previous hybrid membrane research has failed to achieve sufficiently high loadings to establish a percolative network necessary for dual transport, often due to mechanical failure of the membrane at high loading. Using polysulfone and UiO-66-NH2 MOF as a model system, we achieve high MOF loadings (50 wt %) and observe the evolution from single mode to dual transport regimes. The newly formed percolative pathway through the MOF acts as a molecular highway for gases. As the MOF loading increases to 30 wt %, CO2 permeability increases linearly from 5.6 barrers in polysulfone homopolymer to 18 barrers. Crucially, between 30 and 40 wt %, a percolative MOF network arises and the CO2 permeability dramatically rises from 18 to 46 barrers; an eight-fold increase over pure polysulfone, while maintaining selectivity over methane and nitrogen near the pure polymer at 24 and 26, respectively.
摘要:
Nanowires are disclosed which comprise transition metal oxides. The transition metal oxides may include oxides of group II, group III, group IV and lanthanide metals. Also disclosed are methods for making nanowires which comprise injecting decomposition agents into a solution comprising solvents and metallic alkoxide or metallic salt precursors.
摘要:
This disclosure provides systems, methods, and apparatus related to thermoelectric polymer aerogels. In one aspect, a method includes depositing a solution on a substrate. The solution comprises a thermoelectric polymer. Solvent of the solution is removed to form a layer of the thermoelectric polymer. The layer is placed in a polar solvent to form a gel comprising the thermoelectric polymer. The gel is cooled to freeze the polar solvent. The gel is placed in a vacuum environment to sublimate the polar solvent from the gel to form an aerogel comprising the thermoelectric polymer.
摘要:
Various embodiments of the invention describe the synthesis of upconverting nanoparticles (UCNPs), lanthanide-doped hexagonal β-phase sodium yttrium fluoride NaYF4:Er3+/Yb3 nanocrystals, less than 10 nanometers in diameter that are over an order of magnitude brighter under single-particle imaging conditions than existing compositions, allowing visualization of single UCNPs as small (d=4.8 nm) as fluorescent proteins. We use Advanced single-particle characterization and theoretical modeling is demonstrated to find that surface effects become critical at diameters under 20 nm, and that the fluences used in single-molecule imaging change the dominant determinants of nanocrystal brightness. These results demonstrate that factors known to increase brightness in bulk experiments lose importance at higher excitation powers, and that, paradoxically, the brightest probes under single-molecule excitation are barely luminescent at the ensemble level.
摘要:
This disclosure provides systems, methods, and apparatus related to thermoelectric polymer aerogels. In one aspect, a method includes depositing a solution on a substrate. The solution comprises a thermoelectric polymer. Solvent of the solution is removed to form a layer of the thermoelectric polymer. The layer is placed in a polar solvent to form a gel comprising the thermoelectric polymer. The gel is cooled to freeze the polar solvent. The gel is placed in a vacuum environment to sublimate the polar solvent from the gel to form an aerogel comprising the thermoelectric polymer.
摘要:
This disclosure provides systems, methods, and apparatus related to surface doping of nanostructures. In one aspect a plurality of nanostructures is fabricated with a solution-based process using a solvent. The plurality of nanostructures comprises a semiconductor. Each of the plurality of nanostructures has a surface with capping species attached to the surface. The plurality of nanostructures is mixed in the solvent with a dopant compound that includes doping species. During the mixing the capping species on the surfaces of the plurality of nanostructures are replaced by the doping species. Charge carriers are transferred between the doping species and the plurality of nanostructures.
摘要:
This disclosure provides systems, methods, and apparatus related to graded thermoelectric materials. In one aspect, a method includes providing a plurality of nanostructures. The plurality of nanostructures comprise a thermoelectric material, with nanostructures of the plurality of nanostructures having first ligands disposed on surfaces of the nanostructures. The plurality of nanostructures is deposited on a substrate to form a layer. The layer is contacted with a solution containing second ligands. A ligand exchange process occurs where some of the first ligands disposed on the plurality of nanostructures are replaced with the second ligands. A first region of the layer is removed from contact with the solution so that the ligand exchange process does not occur in the first region of the layer, with the ligand exchange process occurring in the layer in contact with the solution. The layer is then removed from contact with the solution.
摘要:
This disclosure provides systems, methods, and apparatus related to graded thermoelectric materials. In one aspect, a method includes providing a plurality of nanostructures. The plurality of nanostructures comprise a thermoelectric material, with nanostructures of the plurality of nanostructures having first ligands disposed on surfaces of the nanostructures. The plurality of nanostructures is deposited on a substrate to form a layer. The layer is contacted with a solution containing second ligands. A ligand exchange process occurs where some of the first ligands disposed on the plurality of nanostructures are replaced with the second ligands. A first region of the layer is removed from contact with the solution so that the ligand exchange process does not occur in the first region of the layer, with the ligand exchange process occurring in the layer in contact with the solution. The layer is then removed from contact with the solution.
摘要:
This disclosure provides systems, methods, and apparatus related to thermoelectric materials. In one aspect, a method includes providing a plurality of nanostructures. The plurality of nanostructures comprise a thermoelectric material, with each nanostructure of the plurality of nanostructures having first ligands disposed on a surface of the nanostructure. The plurality of nanostructures is mixed with a solution containing second ligands and a ligand exchange process occurs in which the first ligands disposed on the plurality of nanostructures are replaced with the second ligands. The plurality of nanostructures is deposited on a substrate to form a layer. The layer is thermally annealed.
摘要:
A thermoelectric device suitable for power generation by the Seebeck effect or heating and cooling by the Peltier effect includes a flexible thermoelectric layer with a flexible heatsink layer. A thermally conductive layer can optionally be included on the side of the thermoelectric layer opposite the flexible heatsink layer. Because of its flexibility and durability, the thermoelectric device can be utilized for products such as a thermoelectric generator or cooling/heating system for consumer products, such as a bedding, clothing, hats, seat cushions, and personal portable devices.