scholarly journals Transparent Monolithic Metal Ion Containing Nanophase Aerogels

1999 ◽  
Vol 581 ◽  
Author(s):  
William M. Risen ◽  
Xiangjun Hu ◽  
Shuang Ji ◽  
Kenneth Littrell
Keyword(s):  
Metal Ion ◽  
Structural Integrity ◽  
High Surface ◽  
High Surface Area ◽  
Visible Range ◽  
High Surface Area Materials ◽  
Kinetics Of ◽  
Subsequent Modification ◽  
Very High ◽  
Kinetics Of Gelation

ABSTRACTThe formation of monolithic and transparent transition metal containing aerogels has been achieved through cooperative interactions of high molecular weight functionalized carbohydrates and silica precursors, which strongly influence the kinetics of gelation. After initial gelation, subsequent modification of the ligating character of the system, coordination of the group VIII metal ions, and supercritical extraction afford the aerogels. The structures at the nanophase level have been probed by photon and electron transmission and neutron scattering techniques to help elucidate the basis for structural integrity together with the small entity sizes that permit transparency in the visible range. They also help with understanding the chemical reactivities of the metal-containing sites in these very high surface area materials. These results are discussed in connection with new reaction studies.

scholarly journals Dissolution Kinetics of International Simple Glass and Formation of Secondary Phases at Very High Surface Area to Solution Ratio in Young Cement Water

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1254
Author(s):  
Karine Ferrand ◽  
Martina Klinkenberg ◽  
Sébastien Caes ◽  
Jenna Poonoosamy ◽  
Wouter Van Renterghem ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Dissolution Kinetics ◽  
Dissolution Behavior ◽  
Secondary Phases ◽  
Residual Rate ◽  
Glass Dissolution ◽  
Ph Decrease ◽  
Kinetics Of ◽  
Very High

Static dissolution experiments were carried out with the reference International Simple Glass under hyperalkaline pH at 70 °C and very high SA/V ratio. Three aspects of glass dissolution behavior were investigated, (1) the rate drop regime and the residual rate (stage II), (2) the formation of secondary phases including thermodynamic aspects, and (3) the microstructure of the interface of altered glass and secondary phases. A very low residual rate of 6 × 10−6 g/m2d was determined based on boron release, which was several orders of magnitude lower than the initial rate established between the start of the experiments and the first sampling on day 59. The presence of a porous layer with a thickness varying between 80 nm and 250 nm and a pore size between 10 nm and 50 nm was observed. CSH phases with a low Ca/Si ratio of 0.3–0.4 and zeolites were also visible at the surface of the altered glass grains, but no glass alteration resumption occurred, probably due to an important pH decrease already at day 59. Thermodynamic calculations assuming congruent glass dissolution and precipitation of the dissolved aqueous species confirmed the precipitation of CSH phases and zeolites.

scholarly journals Comparing postdeposition reactions of electrons and radicals with Pt nanostructures created by focused electron beam induced deposition

2017 ◽  
Vol 8 ◽  
pp. 2410-2424 ◽  
Author(s):  
Julie A Spencer ◽  
Michael Barclay ◽  
Miranda J Gallagher ◽  
Robert Winkler ◽  
Ilyas Unlu ◽  
...  
Keyword(s):  
Electron Beam ◽  
Structural Integrity ◽  
High Surface ◽  
High Surface Area ◽  
Chloride Ions ◽  
Residual Chlorine ◽  
Scanning Electron Microscopy Data ◽  
Electron Beam Induced Deposition ◽  
Electron Stimulated Desorption ◽  
Microscopy Data

The ability of electrons and atomic hydrogen (AH) to remove residual chlorine from PtCl2 deposits created from cis-Pt(CO)2Cl2 by focused electron beam induced deposition (FEBID) is evaluated. Auger electron spectroscopy (AES) and energy-dispersive X-ray spectroscopy (EDS) measurements as well as thermodynamics calculations support the idea that electrons can remove chlorine from PtCl2 structures via an electron-stimulated desorption (ESD) process. It was found that the effectiveness of electrons to purify deposits greater than a few nanometers in height is compromised by the limited escape depth of the chloride ions generated in the purification step. In contrast, chlorine atoms can be efficiently and completely removed from PtCl2 deposits using AH, regardless of the thickness of the deposit. Although AH was found to be extremely effective at chemically purifying PtCl2 deposits, its viability as a FEBID purification strategy is compromised by the mobility of transient Pt–H species formed during the purification process. Scanning electron microscopy data show that this results in the formation of porous structures and can even cause the deposit to lose structural integrity. However, this phenomenon suggests that the use of AH may be a useful strategy to create high surface area Pt catalysts and may reverse the effects of sintering. In marked contrast to the effect observed with AH, densification of the structure was observed during the postdeposition purification of PtC x deposits created from MeCpPtMe3 using atomic oxygen (AO), although the limited penetration depth of AO restricts its effectiveness as a purification strategy to relatively small nanostructures.

Synthesis and Electrochemical Properties of Ternary Co-, Cu- and Ni- Based Metal-Organic Frameworks Electrode for Battery Supercapacitor Hybrid Application

2020 ◽  
Vol 981 ◽  
pp. 17-22
Author(s):  
Amir Luqman Sanusi ◽  
Nurul Khairiyyah Mohd Zain ◽  
Izan Izwan Misnon ◽  
Ahmad Salihin Samsudin ◽  
Rajan Jose
Keyword(s):  
Electrochemical Properties ◽  
Metal Ion ◽  
Electrochemical Impedance ◽  
High Surface ◽  
Metal Organic Frameworks ◽  
High Surface Area ◽  
High Specific Capacitance ◽  
Electrochemical Analysis ◽  
Benzenedicarboxylic Acid ◽  
Metal Organic

Metal-organic frameworks (MOFs) composed by coordination bonds between metal ion with organic linker has a uniform combination of micro and mesoporous structures has been used for several application including battery supercapacitor hybrid. (BSH). In BSH, MOF offer several advantages including high surface area, porous, and structure tunability. This paper reports the synthesis of ternary MOF of copper (Cu), nickel (Ni) and cobalt (Co) with 1,4-benzenedicarboxylic acid. The Co/Cu/Ni-MOF is synthesized using hydrothermal method at 160 °C for 12h and further develop as a BSH electrode. The physicochemical properties of MOF were characterized using FESEM, FTIR, XRD, BET and the electrochemical properties were evaluated using cyclic voltammetry (CV), charge-discharge cycling (CDC) and electrochemical impedance spectroscopy (EIS). Electrochemical analysis indicated that the MOF has high specific capacitance (CS) of 591 F g-1 at a current density of 1 A g-1 and 519 F g-1 at scan rate of 2 mV s-1, and possess low series resistance (RS) of 0.44 Ω and equivalent distributed resistance (Rd) of 1.07 Ω.

HSA-Cercanam®: A New Material with a Continuous Nanopore Network

2003 ◽  
Vol 788 ◽  
Author(s):  
A. Akash ◽  
B. Nair ◽  
K. Minnick ◽  
M. Wilson ◽  
J. Hartvigsen
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Unique Nature ◽  
Catalyst Type ◽  
Reaction Chambers ◽  
New Material ◽  
One Step ◽  
Very High ◽  
Functional Ceramic

ABSTRACTA novel nano-ceramic material, called HSA-CERCANAM®, which has a very high surface area with a nanopore network has been developed. HSA-CERCANAM® can be casted in various shapes and forms resulting in a monolithic piece that has surface area as high as 80–100 m2/g. The surface area and the nanopore network of HSA-CERCANAM® remains stable at temperatures as high as 1000°C. Furthermore, the unique nature of HSA-CERCANAM® allows it to be casted on and around features, either sacrificial or permanent. Using sacrificial features, microchannels can be incorporated internally into the monolithic HSA-CERCANAM® piece in a simple, one-step process. Further, this monolithic ceramic component, which has an intrinsically high surface area and a nanopore network, can be infiltrated with a desired catalyst. This could offer clear technological advantages over currently available microreactors. The surface area, porosity, catalyst type and infiltration levels are some of the ways in which tailored microstructures can be realized in components such as mixers, heat exchangers, extractors, filters or reaction chambers thereby leading to highly efficient, multi-functional ceramic micro-devices.

Adsorption of different dyes from aqueous solution using Si-MCM-41 having very high surface area

2016 ◽  
Vol 23 (5) ◽  
pp. 1227-1237 ◽  
Author(s):  
Haribandhu Chaudhuri ◽  
Subhajit Dash ◽  
Ashis Sarkar
Keyword(s):  
Aqueous Solution ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Very High ◽  
Mcm 41

Three-Dimensional Cage Type Mesoporous CN-Based Hybrid Material with Very High Surface Area and Pore Volume

2007 ◽  
Vol 19 (17) ◽  
pp. 4367-4372 ◽  
Author(s):  
Ajayan Vinu ◽  
Pavuluri Srinivasu ◽  
Dhanashri P. Sawant ◽  
Toshiyuki Mori ◽  
Katsuhiko Ariga ◽  
...  
Keyword(s):  
Surface Area ◽  
Hybrid Material ◽  
Pore Volume ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
Very High
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