On the Conversion of Bauxite Ores to Highly Activated Alumina Media for Water Remediation

Good quality drinking water is necessary to maintain a high quality of life. Millions lack access to clean and safe drinking water, and current trends suggest that billions will face acute water shortages in the coming decades. Development of new materials has led to technological impacts on water purification, from desalination membranes to atmospheric water scavenging. However, the most challenging aspect of technological solutions is cost: if the community being serviced cannot afford the solution, it is not likely to be sustainable. Repurposing Earth-abundant materials to replace highly engineered solutions is an atractive solution. Herein, minimal processing of bauxite rocks produces a high-porosity and reactive activated alumina in situ, without purification directly from the ore. This acid-treated, thermally activated bauxite (ATAB) exhibits a high surface area of 401 ± 6 m2 g−1, a 40-fold increase relative to its parent ore, and a 2× increase relative to the state-of-the-art fluoride adsorbent, activated alumina. The composition, preparation, and mechanism of adsorption are studied by X-ray diffraction, X-ray photoelectron spectroscopy, and multiple-quantum magic-angle spinning 27Al nuclear magnetic resonance (NMR). The maximum adsorption density of ATAB is comparable with that of activated alumina, but ATAB requires fewer processing steps, thus warranting future consideration as a primary adsorbent of choice for fluoride removal from water

Influence of Surface Composition on Electronic Transport through Naked Nanocrystal Networks

Influence of Surface Composition on Electronic Transport through Naked Nanocrystal Network

Nanocrystal-based active layers with tailored interfaces and architectures for advanced energy applications

The properties of tasked nanocrystals in energy-related devices are strongly dependent on the presence and chem. nature of ligands at their surface, and the architectures they assume in electroactive layers. Here we will describe an exceptionally versatile class of reagents for native ligand stripping of carboxylate-, phosphonate- and amine- passivated nanocrystals, resulting in either bare or BF4-/DMF-passivated surfaces depending on the material used. These reagents were effective both for thin films of nanocrystals as well as their dispersions. Significantly, no etching of the nanocrystals was obsd. We will also show that dispersions of ligand stripped nanocrystals are useful as nanoinks and are amenable to architecturing at the mesoscale using suitable macromol. tamplating agents that make particular use of specific and dynamic mol. interactions at the nanocrystal surface. Structured electroactive layers as such are poised to overcome challenges assocd. with electrochem. reactions occurring at accessible interfaces

Nanocrystal Superlattice Embedded within an Inorganic Semiconducting Matrix by in Situ Ligand Exchange: Fabrication and Morphology

The authors carry out ligand exchange reaction replacing bulky insulating org. ligands with inorg. chalcogenidometallate clusters in nanocrystal assemblies floating at the gas-liq. interface. The mobility of the nanocrystals allows lattice contraction without significantly diminishing the ordering obsd. by grazing incidence X-ray scattering and transmission electron microscopy (TEM). This approach produces inorg. nanocomposite films one to a few nanocrystals in thickness with highly regular arrangements of nanocrystals. Anal. of free-standing nanocrystal membranes by low-dose, aberration-cor. TEM allows direct visualization of the nanocrystal-matrix interface

Bond behaviour of fusion bonded epoxy coated reinforcement Influence of bar rib geometry

SIGLEAvailable from British Library Document Supply Centre- DSC:DX97913 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Modulation of Carrier Type in Nanocrystal-in-Matrix Composites by Interfacial Doping

Inorganic nanocomposites synthesized by combination of colloidal nanocrystals (NCs) and inorganic clusters have recently emerged as new materials with novel and unique functionalities. Much of the demonstrated promise of nanocomposites derives from the unique interactions between NC and matrix componentsthis generates new material properties, which direct unique transport behavior in the overall solid or nanocompositebe it mass, charge, or heat. While measured empirically, it has remained largely impossible to take an a priori look at material properties and use those as a guideline to design desired transport behavior. Fundamentally, this is because the structural and electronic changes manifest at those interfaces have remained hidden from examination. Here, we provide experimental evidence that transport behavior in nanocrystal-in-matrix (NIM) composites is dictated primarily by interfacial charge transfer associated with electronic and structural reconstructions as the composite forms. Our approach building continuous composite superlattices serves as a starting point for systematic probing of the nanointerface of NIM composites via ultrathin films. A combination of field effect transistor device characterization and photoemission spectroscopy reveals the systematic dependence of the polarity of charge transfer on the selection of matrix materials in NIM composites. We use this insight to combine, by design, different components to tune the carrier type in NIM composites

Chemically Directing D-Block Heterometallics to Nanocrystal Surfaces as Molecular Beacons of Surface Structure

Our understanding of structure and bonding in nanoscale materials is incomplete without knowledge of their surface structure. Needed are better surveying capabilities responsive not only to different atoms at the surface, but also their respective coordination environments. We report here that d-block organometallics, when placed at nanocrystal surfaces through heterometallic bonds, serve as molecular beacons broadcasting local surface structure in atomic detail. This unique ability stems from their elemental specificity and the sensitivity of their d-orbital level alignment to local coordination environment, which can be assessed spectroscopically. Re-surfacing cadmium and lead chalcogenide nanocrystals with iron- or ruthenium-based molecular beacons is readily accomplished with trimethylsilylated cyclopentadienyl metal carbonyls. For PbSe nanocrystals with iron-based beacons, we show how core-level X-ray spectroscopies and DFT calculations enrich our understanding of both charge and atomic reorganization at the surface when beacons are bound.Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy DE-AC02-05CH11231Department of Defense through the National Defense Science & Engineering Graduate Fellowship ProgramU.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship (SULI) programU.S. Department of Energy, Office of Science, Office of Basic Energy Sciences DE-AC02-76SF00515Chemical Engineerin