Role of pore size on the electrochemical oxidation of 5-hydroxytryptophan in a silica sol?gel matrix

2004 ◽  
Vol 8 (11) ◽  
pp. 886-891 ◽  
Author(s):  
Jamie L. Cohen ◽  
James A. Cox
Keyword(s):  
Pore Size ◽  
Electrochemical Oxidation ◽  
Sol Gel ◽  
Silica Sol

scholarly journals Electroanalysis based on stand-alone matrices and electrode-modifying films with silica sol-gel frameworks: a review

2020 ◽  
Vol 24 (11-12) ◽  
pp. 2617-2631
Author(s):  
Krzysztof Miecznikowski ◽  
James A. Cox
Keyword(s):  
Ionic Liquids ◽  
Solid State ◽  
Pore Size ◽  
Size Structure ◽  
Sol Gel ◽  
Silica Sol ◽  
Size Exclusion ◽  
Ionic Conductors ◽  
Power Sources ◽  
Analytical Applications

Abstract Silica sol-gel matrices and its organically modified analogues that contain aqueous electrolytes, ionic liquids, or other ionic conductors constitute stand-alone solid-state electrochemical cells when hosting electrodes or serve as modifying films on working electrodes in conventional cells. These materials facilitate a wide variety of analytical applications and are employed in various designs of power sources. In this review, analytical applications are the focus. Solid-state cells that serve as gas sensors, including in chromatographic detectors of gas-phase analytes, are described. Sol-gel films that modify working electrodes to perform functions such as hosting electrochemical catalysts and acting as size-exclusion moieties that protect the electrode from passivation by adsorption of macromolecules are discussed with emphasis on pore size, structure, and orientation. Silica sol-gel chemistry has been studied extensively; thus, factors that control its general properties as frameworks for solid-state cells and for thin films on the working electrode are well characterized. Here, recent advances such as the use of dendrimers and of nanoscale beads in conjunction with electrochemically assisted deposition of silica to template pore size and distribution are emphasized. Related topics include replacing aqueous solutions as the internal electrolyte with room-temperature ionic liquids, using the sol-gel as an anchor for functional groups and modifying electrodes with silica-based composites.

scholarly journals Orienting the Pore Morphology of Core-Shell Magnetic Mesoporous Silica with the Sol-Gel Temperature. Influence on MRI and Magnetic Hyperthermia Properties

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 971
Author(s):  
Alexandre Adam ◽  
Ksenia Parkhomenko ◽  
Paula Duenas-Ramirez ◽  
Clémence Nadal ◽  
Geoffrey Cotin ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Pore Size ◽  
Sol Gel ◽  
Specific Area ◽  
Magnetic Hyperthermia ◽  
Core Shell ◽  
Pore Morphology ◽  
Channel Network ◽  
Size And Morphology

The controlled design of robust, well reproducible, and functional nanomaterials made according to simple processes is of key importance to envision future applications. In the field of porous materials, tuning nanoparticle features such as specific area, pore size and morphology by adjusting simple parameters such as pH, temperature or solvent is highly needed. In this work, we address the tunable control of the pore morphology of mesoporous silica (MS) nanoparticles (NPs) with the sol-gel reaction temperature (Tsg). We show that the pore morphology of MS NPs alone or of MS shell covering iron oxide nanoparticles (IO NPs) can be easily tailored with Tsg orienting either towards stellar (ST) morphology (large radial pore of around 10 nm) below 80 °C or towards a worm-like (WL) morphology (small randomly oriented pores channel network, of 3–4 nm pore size) above 80 °C. The relaxometric and magnetothermal features of IO@STMS or IO@WLMS core shell NPs having respectively stellar or worm-like morphologies are compared and discussed to understand the role of the pore structure for MRI and magnetic hyperthermia applications.

scholarly journals Better understanding of the role of SiO2, P2O5 and Al2O3 on the spectroscopic properties of Yb3+ doped silica sol-gel glasses

2018 ◽  
Vol 482 ◽  
pp. 46-51 ◽  
Author(s):  
Benoit Glorieux ◽  
Turkka Salminen ◽  
Jonathan Massera ◽  
Mika Lastusaari ◽  
Laeticia Petit
Keyword(s):  
Sol Gel ◽  
Spectroscopic Properties ◽  
Silica Sol ◽  
Gel Glasses

The Role of Chemical Additives in Sol-Gel Processing

1986 ◽  
Vol 73 ◽  
Author(s):  
L. L. Hench ◽  
G. Orcel ◽  
J. L. Nogues
Keyword(s):  
Chemical Reactions ◽  
Acid Catalysis ◽  
Structural Model ◽  
Sol Gel ◽  
Silica Sol ◽  
Chemical Additives ◽  
Solubility Test ◽  
Acid Solubility ◽  
Gel Processing

ABSTRACTThe effect of various concentrations of formamide with and without acid catalysis on TMOS derived silica sol and gel structures and physical properties is described using a quantitative structural model. The model is based upon 29Si NMR, SAXS, Raman and FTIR spectroscopy, and an acid solubility test. Changes in chemical reactions during drying due to formamide are presented using FTIR, DSC and TGA data.

Heteropoly Acids Supported on Sol-Gel Matrices and Their Catalytic Activity and Selectivity

1998 ◽  
Vol 549 ◽  
Author(s):  
D.E. Grandstaff ◽  
M. D. Paciolla ◽  
L.T. Sein ◽  
R. Jacob ◽  
K. Narielwala ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Carbon Materials ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Silica Sol ◽  
Heterogeneous Reactions ◽  
Heteropoly Acids ◽  
Oxide Substrates ◽  
Silica Matrices

AbstractHeteropoly acids (HPA) are well known solid acids as well as oxidation catalysts. They find application in both homogeneous and heterogeneous reactions. As catalysts, problems associated with surface area and instability are diminished by supporting the HPA. It has been reported that supporting these materials on oxide substrates or porous carbon materials has resulted in some degree of instability. It has also been shown that encapsulating HPA in sol-gel silica matrices has produced an increase in catalytic performance without compromising the catalytic activity of the HPA. In this work, we analyzed the activity of a silica sol-gel supported HPA catalyst. The reaction which was chosen to illustrate such issues was the oxidation/dehydration of 1-butanol. In addition, the specific role of the support in the catalytic process is described. In this work, we characterized the silica-sol gel supported HPA catalyst to try to understand the effect of preparation in the overall catalytic selectivity and activity.

scholarly journals A simple approach to prepare fluorescent molecularly imprinted nanoparticles

RSC Advances ◽  
2021 ◽  
Vol 11 (13) ◽  
pp. 7732-7737
Author(s):  
Fenying Wang ◽  
Dan Wang ◽  
Tingting Wang ◽  
Yu Jin ◽  
Baoping Ling ◽  
...  
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Sol Gel ◽  
Silica Sol ◽  
Simple Approach ◽  
Imprinted Polymer ◽  
Molecularly Imprinted ◽  
Low Toxicity ◽  
Good Biocompatibility ◽  
Molecularly Imprinted Nanoparticles

Fluorescent molecularly imprinted polymer (FMIP) gains great attention in many fields due to their low cost, good biocompatibility and low toxicity. Here, a high-performance FMIP was prepared based on the autocatalytic silica sol–gel reaction.

scholarly journals Sodium Solid Electrolytes: NaxAlOy Bilayer-System Based on Macroporous Bulk Material and Dense Thin-Film

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 854
Author(s):  
Antonia Hoppe ◽  
Cornelius Dirksen ◽  
Karl Skadell ◽  
Michael Stelter ◽  
Matthias Schulz ◽  
...  
Keyword(s):  
Pore Size ◽  
Bulk Material ◽  
Sol Gel ◽  
Dense Layer ◽  
X Ray Diffraction ◽  
Bilayer System ◽  
Step Procedure ◽  
Short Circuits ◽  
Α Al2o3 ◽  
Sol Gel Synthesis

A new preparation concept of a partially porous solid-state bilayer electrolyte (BE) for high-temperature sodium-ion batteries has been developed. The porous layer provides mechanical strength and is infiltrated with liquid and highly conductive NaAlCl4 salt, while the dense layer prevents short circuits. Both layers consist, at least partially, of Na-β-alumina. The BEs are synthesized by a three-step procedure, including a sol-gel synthesis, the preparation of porous, calcined bulk material, and spin coating to deposit a dense layer. A detailed study is carried out to investigate the effect of polyethylene oxide (PEO) concentration on pore size and crystallization of the bulk material. The microstructure and crystallographic composition are verified for all steps via mercury intrusion, X-ray diffraction, and scanning electron microscopy. The porous bulk material exhibits an unprecedented open porosity for a NaxAlOy bilayer-system of ≤57% with a pore size of ≈200–300 nm and pore volume of ≤0.3 cm3∙g−1. It contains high shares of crystalline α-Al2O3 and Na-β-alumina. The BEs are characterized by impedance spectroscopy, which proved an increase of ionic conductivity with increasing porosity and increasing Na-β-alumina phase content in the bulk material. Ion conductivity of up to 0.10 S∙cm−1 at 300 °C is achieved.

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