MICROPOROUS and mesoporous inorganic solids (with pore diameters of ≤20 A and ∼20–500 A respectively)1 have found great utility as catalysts and sorption media because of their large internal surface area. Typical microporous materials are the crystalline framework solids, such as zeolites2, but the largest pore dimensions found so far are ∼10–12 A for some metallophosphates3–5 and ∼14 A for the mineral cacoxenite6. Examples of mesoporous solids include silicas7 and modified layered materials8–11, but these are invariably amorphous or paracrystalline, with pores that are irregularly spaced and broadly distributed in size8,12. Pore size can be controlled by intercalation of layered silicates with a surfactant species9,13, but the final product retains, in part, the layered nature of the precursor material. Here we report the synthesis of mesoporous solids from the calcination of aluminosilicate gels in the presence of surfactants. The material14,15 possesses regular arrays of uniform channels, the dimensions of which can be tailored (in the range 16 A to 100 A or more) through the choice of surfactant, auxiliary chemicals and reaction conditions. We propose that the formation of these materials takes place by means of a liquid-crystal 'templating' mechanism, in which the silicate material forms inorganic walls between ordered surfactant micelles.

Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism

The Li-S battery has been under intense scrutiny for over two decades, as it offers the possibility of high gravimetric capacities and theoretical energy densities ranging up to a factor of five beyond conventional Li-ion systems. Herein, we report the feasibility to approach such capacities by creating highly ordered interwoven composites. The conductive mesoporous carbon framework precisely constrains sulphur nanofiller growth within its channels and generates essential electrical contact to the insulating sulphur. The structure provides access to Li+ ingress/egress for reactivity with the sulphur, and we speculate that the kinetic inhibition to diffusion within the framework and the sorption properties of the carbon aid in trapping the polysulphides formed during redox. Polymer modification of the carbon surface further provides a chemical gradient that retards diffusion of these large anions out of the electrode, thus facilitating more complete reaction. Reversible capacities up to 1,320 mA h g(-1) are attained. The assembly process is simple and broadly applicable, conceptually providing new opportunities for materials scientists for tailored design that can be extended to many different electrode materials.

http://dns2.asia.edu.tw/~ysho/YSHO-English/1000%20WC/PDF/Nat%20Mat8,%20500.pdf

A highly ordered nanostructured carbon–sulphur cathode for lithium–sulphur batteries

A critical review of adsorption methods that are currently used in the characterization of ordered organic−inorganic nanocomposite materials is presented, and the adsorption methodology that is potentially useful for this characterization, but has not yet been applied, is discussed. The ordered organic−inorganic nanocomposites include surface-functionalized ordered mesoporous materials (OMMs) with siliceous frameworks (synthesized either via postsynthesis surface modification or via direct co-condensation method), periodic mesoporous organosilicas, and surfactant-containing OMMs. This review covers the methods for determination of the specific surface area and pore volume. The available methods for mesopore size analysis are critically compared and evaluated, with special emphasis on the recent developments related to the application of advanced computational methods for studying adsorption in porous media and to the direct modeling of adsorption using highly ordered surface-functionalized OMMs as model a...

Gas adsorption characterization of ordered organic-inorganic nanocomposite materials

Changes in portlandite morphology with solvent composition: Atomistic simulations and experiment

Pore size determination in modified micro- and mesoporous materials. Pitfalls and limitations in gas adsorption data analysis

The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms

The Determination of Pore Volume and Area Distributions in Porous Substances

The Determination of Pore Volume and Area Distributions in Porous Substances. II. Comparison between Nitrogen Isotherm and Mercury Porosimeter Methods

This paper will show that the assumption of a simple Gaussian or Maxwellian distribution of pore sizes is inadequate for many adsorbents. It will also show that Oulton’s assumption of constant thickness for the physically adsorbed layer, while adequate for a finely porous material such as that to which he applied it (a cracking catalyst with a pore area maximum at radius 26.5 A.), is inadequate to deal with more coarsely porous adsorbents. A formal analysis of the relationship between nitrogen desorption isotherms at liquid nitrogen temperatures and the distribution of pore volume and area with respect to pore radius will be made on the assumption that equilibrium between the gas phase and the adsorbed phase during desorption is determined by two mechanisms: (1) physical adsorption on the pore walls (which would occur to the same extent whether the area involved constituted walls of pores or a flat surface impenetrable to nitrogen), and (2) capillary condensation in what Oulton5 has called the “inner capillary volume.” Results of the analysis will be applied to several adsorbents utilizing the experimental data used by Shul12 to provide a functional relationship between thickness of physically adsorbed layer and relative pressure, and utilizing the classical Kelvin equation, relating vapor pressure depression to capillary radius, to define the relationship between volume of capillary condensate and relative pressure.

(CONTRIBUTION FROM THE MULTIPLE FELLOWSHIP OF BAUGH AND SONS COMPANY, MELLOX INSTITUTE) The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms

Elliott P. Barrett

Papers

The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms

The Determination of Pore Volume and Area Distributions in Porous Substances

The Determination of Pore Volume and Area Distributions in Porous Substances. II. Comparison between Nitrogen Isotherm and Mercury Porosimeter Methods

(CONTRIBUTION FROM THE MULTIPLE FELLOWSHIP OF BAUGH AND SONS COMPANY, MELLOX INSTITUTE) The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms

Thermal Effects Produced by the Exposure of Massive Gold to Saturated Water Vapor