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Nanoporous Materials (nanoporou + material)

Distribution by Scientific Domains
Chemistry57%
Polymers and Materials Science28%

Selected Abstracts

Graphene-Based Nanoporous Materials Assembled by Mediation of Polyoxometalate Nanoparticles

ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010
Ding Zhou
Abstract A kind of graphene-based nanoporous material is prepared through assembling graphene sheets mediated through polyoxometalate nanoparticles. Owing to the strong interaction between graphene and polyoxometalate, 2D graphene sheets with honeycomb-latticed carbon atoms could assemble into a porous structure, in which 3D polyoxometalate nanoparticles serve as the crosslinkers. Nitrogen and hydrogen sorption analysis reveal that the as-prepared graphene-based hybrid material possesses a specific surface area of 680 m2 g,1 and a hydrogen uptake volume of 0.8,1.3 wt%. Infrared spectrometry is used to probe the electron density changes of polyoxometalate particle in the redox-cycle and to verify the interaction between graphene and polyoxometalate. The as-prepared graphene-based materials are further characterized by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. [source]

Charged soc metal-organic framework for high-efficacy H2 adsorption and syngas purification: Atomistic simulation study

AICHE JOURNAL, Issue 9 2009
Jianwen Jiang
Abstract H2 adsorption and syngas purification in charged soc metal-organic framework are investigated using atomistic simulations. As experimentally observed, the extraframework NO3, ions are entrapped in carcerand-like capsule with negligible mobility. At low pressure, H2 adsorption occurs concurrently at multiple sites near the exposed indium atoms and organic components. The capsule is accessible at high pressure through the surrounding channels by restricted windows. Adsorption sites identified are remarkably consistent with inelastic neutron scattering measurements. The isotherm and isosteric heat of H2 adsorption predicted match well with experimental data. As loading rises, the isosteric heat remains nearly constant, revealing the homogeneity of adsorption sites. CO2/H2 selectivity in syngas adsorption is up to 600 and substantially higher than other nanoporous materials. With a trace of H2O, the selectivity increases slightly at low pressure due to promoted adsorption of CO2 by H2O bound proximally to the exposed indium atoms, but decreases at high pressure as a consequence of competitive adsorption of H2O over CO2. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Defect profiles in semiconductor structures

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2007
P. G. Coleman
Abstract Variable-energy positron annihilation spectroscopy (VEPAS) has found applications in structural and electronic analysis of thin films and near-surface layers, nanoporous materials, ion implantation, silicon photonics, and vacancy engineering. In all this applied work it is essential that VEPAS is treated as a normal member of the arsenal of spectroscopies available to the semiconductor research community. Examples are presented of how useful insights into current problems in semiconductor physics and technology have been gained by combinations of VEPAS and other techniques such as secondary ion mass spectrometry, transmission electron microscopy, electrical characterization, and optical techniques such as photoluminescence and optically-detected magnetic resonance. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Preparation and characterization of mesoporous materials based on silsesquioxane by block copolymer templating,

POLYMER INTERNATIONAL, Issue 11 2002
Byeong-Gyu Park
Abstract Nanoporous materials were prepared by using silsesquioxane containing three alkoxy groups and a non-hydrolysable organic moiety. The influences of pH and precursor ratios of silsesquioxane and tetraethyl orthosilicate (TEOS) on the preparation of organo-modified periodic mesoporous materials were investigated. These materials were characterized using small angle X-ray scattering, infrared spectroscopy and thermogravimetric analysis. A non-ionic triblock copolymer was used as a structure-directing agent to provide large pores with a high density of silanol groups. It was found that silsesquioxanes could form ordered nanoporous materials in the presence of TEOS by controlling the pH and the co-precursors ratio, despite their structural irregularity. © 2002 Society of Chemical Industry [source]

Understanding Adsorption and Interactions of Alkane Isomer Mixtures in Isoreticular Metal,Organic Frameworks

CHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2007
Li Zhang Dr.
Abstract Novel metal,organic frameworks (MOFs) may lead to advances in adsorption and catalysis owing to their superior properties compared to traditional nanoporous materials. A combination of the grand canonical Monte Carlo method and configurational-bias Monte Carlo simulation was used to evaluate the adsorption isotherms of C4,C6 alkane isomer mixtures in IRMOF-1 and IRMOF-6. The amounts of adsorbed linear and branched alkanes increase with increasing pressure, and the amount of branched alkanes is larger than that of the linear ones. The locations of the alkane isomer reveal that the Zn4O clusters of the IRMOFs are the preferential adsorption sites for the adsorbate molecules. The interaction energy between the Zn4O cluster and the adsorbate is larger than that between the organic linker and the adsorbate. It was further confirmed that the Zn4O cluster plays a much more important role in adsorption by pushing a probe molecule into the pore at positions closer to the Zn4O cluster. It is difficult for branched alkane molecules to approach the Zn4O cluster of IRMOF-6 closely owing to strong spatial hindrance. In addition, the adsorption selectivity is discussed from the viewpoints of thermodynamics and kinetics, and the diffusion behavior of n -butane and 2-methylpropane were investigated to illustrate the relationship between diffusion and adsorption. [source]

Ensemble Measurement of Diffusion: Novel Beauty and Evidence

CHEMPHYSCHEM, Issue 15 2009
Christian Chmelik Dr.
Abstract Recording the evolution of concentration profiles in nanoporous materials opens a new field of diffusion research with particle ensembles. The technique is based on the complementary application of interference microscopy and IR micro-imaging. Combining the virtues of diffusion measurements with solids and fluids, it provides information of unprecedented wealth and visual power on transport phenomena in molecular ensembles. These phenomena include the diverging uptake and release patterns for concentration-dependent diffusivities, the mechanisms of mass transfer at the fluid,solid interface and opposing tendencies in local and global concentration evolution. [source]

Can Metal,Organic Framework Materials Play a Useful Role in Large-Scale Carbon Dioxide Separations?

CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 8 2010
Seda Keskin Dr.
Abstract Metal,organic frameworks (MOFs) are a fascinating class of crystalline nanoporous materials that can be synthesized with a diverse range of pore dimensions, topologies, and chemical functionality. As with other well-known nanoporous materials, such as activated carbon and zeolites, MOFs have potential uses in a range of chemical separation applications because of the possibility of selective adsorption and diffusion of molecules in their pores. We review the current state of knowledge surrounding the possibility of using MOFs in large-scale carbon dioxide separations. There are reasons to be optimistic that MOFs may make useful contributions to this important problem, but there are several critical issues for which only very limited information is available. By identifying these issues, we provide what we hope is a path forward to definitively answering the question posed in our title. [source]